Microsurgical Clipping of an Anterior Communicating Artery Aneurysm Using a Novel Robotic Visualization Tool in Lieu of the Binocular Operating Microscope: Operative Video.

PubMed

Klinger, Daniel R; Reinard, Kevin A; Ajayi, Olaide O; Delashaw, Johnny B

2018-01-01

The binocular operating microscope has been the visualization instrument of choice for microsurgical clipping of intracranial aneurysms for many decades. To discuss recent technological advances that have provided novel visualization tools, which may prove to be superior to the binocular operating microscope in many regards. We present an operative video and our operative experience with the BrightMatterTM Servo System (Synaptive Medical, Toronto, Ontario, Canada) during the microsurgical clipping of an anterior communicating artery aneurysm. To the best of our knowledge, the use of this device for the microsurgical clipping of an intracranial aneurysm has never been described in the literature. The BrightMatterTM Servo System (Synaptive Medical) is a surgical exoscope which avoids many of the ergonomic constraints of the binocular operating microscope, but is associated with a steep learning curve. The BrightMatterTM Servo System (Synaptive Medical) is a maneuverable surgical exoscope that is positioned with a directional aiming device and a surgeon-controlled foot pedal. While utilizing this device comes with a steep learning curve typical of any new technology, the BrightMatterTM Servo System (Synaptive Medical) has several advantages over the conventional surgical microscope, which include a relatively unobstructed surgical field, provision of high-definition images, and visualization of difficult angles/trajectories. This device can easily be utilized as a visualization tool for a variety of cranial and spinal procedures in lieu of the binocular operating microscope. We anticipate that this technology will soon become an integral part of the neurosurgeon's armamentarium. Copyright © 2017 by the Congress of Neurological Surgeons

Construction and characterization of the fringe field monochromator for a field emission gun

PubMed

Mook; Kruit

2000-04-01

Although some microscopes have shown stabilities sufficient to attain below 0.1 eV spectral resolution in high-resolution electron energy loss spectroscopy, the intrinsic energy width of the high brightness source (0.3-0.6 eV) has been limiting the resolution. To lower the energy width of the source to 50 meV without unnecessary loss of brightness, a monochromator has been designed consisting of a short (4 mm) fringe field Wien filter and a 150 nm energy selection slit (nanoslit) both to be incorporated in the gun area of the microscope. A prototype has been built and tested in an ultra-high-vacuum setup (10(-9) mbar). The monochromator, operating on a Schottky field emission gun, showed stable and reproducible operation. The nanoslits did not contaminate and the structure remained stable. By measuring the current through the slit structure a direct image of the beam in the monochromator could be attained and the monochromator could be aligned without the use of a microscope. Good dispersed imaging conditions were found indicating an ultimate resolution of 55 meV. A Mark II fringe field monochromator (FFM) was designed and constructed compatible with the cold tungsten field emitter of the VG scanning transmission microscope. The monochromator was incorporated in the gun area of the microscope at IBM T.J. Watson research center, New York. The monochromator was aligned on 100 kV and the energy distribution measured using the monochromator displayed a below 50 meV filtering capability. The retarding Wien filter spectrometer was used to show a 61 meV EELS system resolution. The FFM is shown to be a monochromator which can be aligned without the use of the electron microscope. This makes it directly applicable for scanning transmission microscopy and low-voltage scanning electron microscopy, where it can lower the resolution loss which is caused by chromatic blur of the spot.

Field-Portable Pixel Super-Resolution Colour Microscope

PubMed Central

Greenbaum, Alon; Akbari, Najva; Feizi, Alborz; Luo, Wei; Ozcan, Aydogan

2013-01-01

Based on partially-coherent digital in-line holography, we report a field-portable microscope that can render lensfree colour images over a wide field-of-view of e.g., >20 mm2. This computational holographic microscope weighs less than 145 grams with dimensions smaller than 17×6×5 cm, making it especially suitable for field settings and point-of-care use. In this lensfree imaging design, we merged a colorization algorithm with a source shifting based multi-height pixel super-resolution technique to mitigate ‘rainbow’ like colour artefacts that are typical in holographic imaging. This image processing scheme is based on transforming the colour components of an RGB image into YUV colour space, which separates colour information from brightness component of an image. The resolution of our super-resolution colour microscope was characterized using a USAF test chart to confirm sub-micron spatial resolution, even for reconstructions that employ multi-height phase recovery to handle dense and connected objects. To further demonstrate the performance of this colour microscope Papanicolaou (Pap) smears were also successfully imaged. This field-portable and wide-field computational colour microscope could be useful for tele-medicine applications in resource poor settings. PMID:24086742

Field-portable pixel super-resolution colour microscope.

PubMed

Greenbaum, Alon; Akbari, Najva; Feizi, Alborz; Luo, Wei; Ozcan, Aydogan

2013-01-01

Based on partially-coherent digital in-line holography, we report a field-portable microscope that can render lensfree colour images over a wide field-of-view of e.g., >20 mm(2). This computational holographic microscope weighs less than 145 grams with dimensions smaller than 17×6×5 cm, making it especially suitable for field settings and point-of-care use. In this lensfree imaging design, we merged a colorization algorithm with a source shifting based multi-height pixel super-resolution technique to mitigate 'rainbow' like colour artefacts that are typical in holographic imaging. This image processing scheme is based on transforming the colour components of an RGB image into YUV colour space, which separates colour information from brightness component of an image. The resolution of our super-resolution colour microscope was characterized using a USAF test chart to confirm sub-micron spatial resolution, even for reconstructions that employ multi-height phase recovery to handle dense and connected objects. To further demonstrate the performance of this colour microscope Papanicolaou (Pap) smears were also successfully imaged. This field-portable and wide-field computational colour microscope could be useful for tele-medicine applications in resource poor settings.

Brightness measurement of an electron impact gas ion source for proton beam writing applications

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

Liu, N.; Santhana Raman, P.; Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583

We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness thatmore » is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.« less

Brightness measurement of an electron impact gas ion source for proton beam writing applications.

PubMed

Liu, N; Xu, X; Pang, R; Raman, P Santhana; Khursheed, A; van Kan, J A

2016-02-01

We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness that is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.

Chip-scale fluorescence microscope based on a silo-filter complementary metal-oxide semiconductor image sensor.

PubMed

Ah Lee, Seung; Ou, Xiaoze; Lee, J Eugene; Yang, Changhuei

2013-06-01

We demonstrate a silo-filter (SF) complementary metal-oxide semiconductor (CMOS) image sensor for a chip-scale fluorescence microscope. The extruded pixel design with metal walls between neighboring pixels guides fluorescence emission through the thick absorptive filter to the photodiode of a pixel. Our prototype device achieves 13 μm resolution over a wide field of view (4.8 mm × 4.4 mm). We demonstrate bright-field and fluorescence longitudinal imaging of living cells in a compact, low-cost configuration.

Ultra-fast bright field and fluorescence imaging of the dynamics of micrometer-sized objects

NASA Astrophysics Data System (ADS)

Chen, Xucai; Wang, Jianjun; Versluis, Michel; de Jong, Nico; Villanueva, Flordeliza S.

2013-06-01

High speed imaging has application in a wide area of industry and scientific research. In medical research, high speed imaging has the potential to reveal insight into mechanisms of action of various therapeutic interventions. Examples include ultrasound assisted thrombolysis, drug delivery, and gene therapy. Visual observation of the ultrasound, microbubble, and biological cell interaction may help the understanding of the dynamic behavior of microbubbles and may eventually lead to better design of such delivery systems. We present the development of a high speed bright field and fluorescence imaging system that incorporates external mechanical waves such as ultrasound. Through collaborative design and contract manufacturing, a high speed imaging system has been successfully developed at the University of Pittsburgh Medical Center. We named the system "UPMC Cam," to refer to the integrated imaging system that includes the multi-frame camera and its unique software control, the customized modular microscope, the customized laser delivery system, its auxiliary ultrasound generator, and the combined ultrasound and optical imaging chamber for in vitro and in vivo observations. This system is capable of imaging microscopic bright field and fluorescence movies at 25 × 106 frames per second for 128 frames, with a frame size of 920 × 616 pixels. Example images of microbubble under ultrasound are shown to demonstrate the potential application of the system.

Ultra-fast bright field and fluorescence imaging of the dynamics of micrometer-sized objects

PubMed Central

Chen, Xucai; Wang, Jianjun; Versluis, Michel; de Jong, Nico; Villanueva, Flordeliza S.

2013-01-01

High speed imaging has application in a wide area of industry and scientific research. In medical research, high speed imaging has the potential to reveal insight into mechanisms of action of various therapeutic interventions. Examples include ultrasound assisted thrombolysis, drug delivery, and gene therapy. Visual observation of the ultrasound, microbubble, and biological cell interaction may help the understanding of the dynamic behavior of microbubbles and may eventually lead to better design of such delivery systems. We present the development of a high speed bright field and fluorescence imaging system that incorporates external mechanical waves such as ultrasound. Through collaborative design and contract manufacturing, a high speed imaging system has been successfully developed at the University of Pittsburgh Medical Center. We named the system “UPMC Cam,” to refer to the integrated imaging system that includes the multi-frame camera and its unique software control, the customized modular microscope, the customized laser delivery system, its auxiliary ultrasound generator, and the combined ultrasound and optical imaging chamber for in vitro and in vivo observations. This system is capable of imaging microscopic bright field and fluorescence movies at 25 × 106 frames per second for 128 frames, with a frame size of 920 × 616 pixels. Example images of microbubble under ultrasound are shown to demonstrate the potential application of the system. PMID:23822346

Quantitative label-free sperm imaging by means of transport of intensity

NASA Astrophysics Data System (ADS)

Poola, Praveen Kumar; Pandiyan, Vimal Prabhu; Jayaraman, Varshini; John, Renu

2016-03-01

Most living cells are optically transparent which makes it difficult to visualize them under bright field microscopy. Use of contrast agents or markers and staining procedures are often followed to observe these cells. However, most of these staining agents are toxic and not applicable for live cell imaging. In the last decade, quantitative phase imaging has become an indispensable tool for morphological characterization of the phase objects without any markers. In this paper, we report noninterferometric quantitative phase imaging of live sperm cells by solving transport of intensity equations with recorded intensity measurements along optical axis on a commercial bright field microscope.

Seamless stitching of tile scan microscope images.

PubMed

Legesse, F B; Chernavskaia, O; Heuke, S; Bocklitz, T; Meyer, T; Popp, J; Heintzmann, R

2015-06-01

For diagnostic purposes, optical imaging techniques need to obtain high-resolution images of extended biological specimens in reasonable time. The field of view of an objective lens, however, is often smaller than the sample size. To image the whole sample, laser scanning microscopes acquire tile scans that are stitched into larger mosaics. The appearance of such image mosaics is affected by visible edge artefacts that arise from various optical aberrations which manifest in grey level jumps across tile boundaries. In this contribution, a technique for stitching tiles into a seamless mosaic is presented. The stitching algorithm operates by equilibrating neighbouring edges and forcing the brightness at corners to a common value. The corrected image mosaics appear to be free from stitching artefacts and are, therefore, suited for further image analysis procedures. The contribution presents a novel method to seamlessly stitch tiles captured by a laser scanning microscope into a large mosaic. The motivation for the work is the failure of currently existing methods for stitching nonlinear, multimodal images captured by our microscopic setups. Our method eliminates the visible edge artefacts that appear between neighbouring tiles by taking into account the overall illumination differences among tiles in such mosaics. The algorithm first corrects the nonuniform brightness that exists within each of the tiles. It then compensates for grey level differences across tile boundaries by equilibrating neighbouring edges and forcing the brightness at the corners to a common value. After these artefacts have been removed further image analysis procedures can be applied on the microscopic images. Even though the solution presented here is tailored for the aforementioned specific case, it could be easily adapted to other contexts where image tiles are assembled into mosaics such as in astronomical or satellite photos. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

A new method to detect and correct sample tilt in scanning transmission electron microscopy bright-field imaging.

PubMed

Brown, H G; Ishikawa, R; Sánchez-Santolino, G; Lugg, N R; Ikuhara, Y; Allen, L J; Shibata, N

2017-02-01

Important properties of functional materials, such as ferroelectric shifts and octahedral distortions, are associated with displacements of the positions of lighter atoms in the unit cell. Annular bright-field scanning transmission electron microscopy is a good experimental method for investigating such phenomena due to its ability to image light and heavy atoms simultaneously. To map atomic positions at the required accuracy precise angular alignment of the sample with the microscope optical axis is necessary, since misalignment (tilt) of the specimen contributes to errors in position measurements of lighter elements in annular bright-field imaging. In this paper it is shown that it is possible to detect tilt with the aid of images recorded using a central bright-field detector placed within the inner radius of the annular bright-field detector. For a probe focus near the middle of the specimen the central bright-field image becomes especially sensitive to tilt and we demonstrate experimentally that misalignment can be detected with a precision of less than a milliradian, as we also confirm in simulation. Coma in the probe, an aberration that can be misidentified as tilt of the specimen, is also investigated and it is shown how the effects of coma and tilt can be differentiated. The effects of tilt may be offset to a large extent by shifting the diffraction plane detector an amount equivalent to the specimen tilt and we provide an experimental proof of principle of this using a segmented detector system. Copyright © 2016 Elsevier B.V. All rights reserved.

Programmable Colored Illumination Microscopy (PCIM): A practical and flexible optical staining approach for microscopic contrast enhancement

NASA Astrophysics Data System (ADS)

Zuo, Chao; Sun, Jiasong; Feng, Shijie; Hu, Yan; Chen, Qian

2016-03-01

Programmable colored illumination microscopy (PCIM) has been proposed as a flexible optical staining technique for microscopic contrast enhancement. In this method, we replace the condenser diaphragm of a conventional microscope with a programmable thin film transistor-liquid crystal display (TFT-LCD). By displaying different patterns on the LCD, numerous established imaging modalities can be realized, such as bright field, dark field, phase contrast, oblique illumination, and Rheinberg illuminations, which conventionally rely on intricate alterations in the respective microscope setups. Furthermore, the ease of modulating both the color and the intensity distribution at the aperture of the condenser opens the possibility to combine multiple microscopic techniques, or even realize completely new methods for optical color contrast staining, such as iridescent dark-field and iridescent phase-contrast imaging. The versatility and effectiveness of PCIM is demonstrated by imaging of several transparent colorless specimens, such as unstained lung cancer cells, diatom, textile fibers, and a cryosection of mouse kidney. Finally, the potentialities of PCIM for RGB-splitting imaging with stained samples are also explored by imaging stained red blood cells and a histological section.

Advantages of using newly developed quartz contact lens with slit illumination from operating microscope.

PubMed

Kiyokawa, Masatoshi; Sakuma, Toshiro; Hatano, Noriko; Mizota, Atsushi; Tanaka, Minoru

2009-06-01

The purpose of this article is to report the characteristics and advantages of using a newly designed quartz contact lens with slit illumination from an operating microscope for intraocular surgery. The new contact lens is made of quartz. The lens is convex-concave and is used in combination with slit illumination from an operating microscope. The optical properties of quartz make this lens less reflective with greater transmittance. The combination of a quartz contact lens with slit illumination provided a brighter and wider field of view than conventional lenses. This system enabled us to perform bimanual vitrectomy and scleral buckling surgery without indirect ophthalmoscope. Small intraocular structures in the posterior pole or in the periphery were detected more easily. In conclusion, the newly designed quartz lens with slit beam illumination from an operating microscope provided a bright, clear and wide surgical field, and allowed intraocular surgery to be performed more easily.

Toward giga-pixel nanoscopy on a chip: a computational wide-field look at the nano-scale without the use of lenses

PubMed Central

McLeod, Euan; Luo, Wei; Mudanyali, Onur; Greenbaum, Alon

2013-01-01

The development of lensfree on-chip microscopy in the past decade has opened up various new possibilities for biomedical imaging across ultra-large fields of view using compact, portable, and cost-effective devices. However, until recently, its ability to resolve fine features and detect ultra-small particles has not rivalled the capabilities of the more expensive and bulky laboratory-grade optical microscopes. In this Frontier Review, we highlight the developments over the last two years that have enabled computational lensfree holographic on-chip microscopy to compete with and, in some cases, surpass conventional bright-field microscopy in its ability to image nano-scale objects across large fields of view, yielding giga-pixel phase and amplitude images. Lensfree microscopy has now achieved a numerical aperture as high as 0.92, with a spatial resolution as small as 225 nm across a large field of view e.g., >20 mm2. Furthermore, the combination of lensfree microscopy with self-assembled nanolenses, forming nano-catenoid minimal surfaces around individual nanoparticles has boosted the image contrast to levels high enough to permit bright-field imaging of individual particles smaller than 100 nm. These capabilities support a number of new applications, including, for example, the detection and sizing of individual virus particles using field-portable computational on-chip microscopes. PMID:23592185

Toward giga-pixel nanoscopy on a chip: a computational wide-field look at the nano-scale without the use of lenses.

PubMed

McLeod, Euan; Luo, Wei; Mudanyali, Onur; Greenbaum, Alon; Ozcan, Aydogan

2013-06-07

The development of lensfree on-chip microscopy in the past decade has opened up various new possibilities for biomedical imaging across ultra-large fields of view using compact, portable, and cost-effective devices. However, until recently, its ability to resolve fine features and detect ultra-small particles has not rivalled the capabilities of the more expensive and bulky laboratory-grade optical microscopes. In this Frontier Review, we highlight the developments over the last two years that have enabled computational lensfree holographic on-chip microscopy to compete with and, in some cases, surpass conventional bright-field microscopy in its ability to image nano-scale objects across large fields of view, yielding giga-pixel phase and amplitude images. Lensfree microscopy has now achieved a numerical aperture as high as 0.92, with a spatial resolution as small as 225 nm across a large field of view e.g., >20 mm(2). Furthermore, the combination of lensfree microscopy with self-assembled nanolenses, forming nano-catenoid minimal surfaces around individual nanoparticles has boosted the image contrast to levels high enough to permit bright-field imaging of individual particles smaller than 100 nm. These capabilities support a number of new applications, including, for example, the detection and sizing of individual virus particles using field-portable computational on-chip microscopes.

Resolution of 90 nm (lambda/5) in an optical transmission microscope with an annular condenser.

PubMed

Vainrub, Arnold; Pustovyy, Oleg; Vodyanoy, Vitaly

2006-10-01

Resolution of 90 nm was achieved with a research microscope simply by replacing the standard bright-field condenser with a homebuilt illumination system with a cardioid annular condenser. Diffraction gratings with 100 nm width lines as well as less than 100 nm size features of different-shaped objects were clearly visible on a calibrated microscope test slide. The resolution increase results from a known narrower diffraction pattern in coherent illumination for the annular aperture compared with the circular aperture. This explanation is supported by an excellent accord of calculated and measured diffraction patterns for a 50 nm radius disk.

Eukaryotic cell flattening

NASA Astrophysics Data System (ADS)

Bae, Albert; Westendorf, Christian; Erlenkamper, Christoph; Galland, Edouard; Franck, Carl; Bodenschatz, Eberhard; Beta, Carsten

2010-03-01

Eukaryotic cell flattening is valuable for improving microscopic observations, ranging from bright field to total internal reflection fluorescence microscopy. In this talk, we will discuss traditional overlay techniques, and more modern, microfluidic based flattening, which provides a greater level of control. We demonstrate these techniques on the social amoebae Dictyostelium discoideum, comparing the advantages and disadvantages of each method.

Transmission environmental scanning electron microscope with scintillation gaseous detection device.

PubMed

Danilatos, Gerasimos; Kollia, Mary; Dracopoulos, Vassileios

2015-03-01

A transmission environmental scanning electron microscope with use of a scintillation gaseous detection device has been implemented. This corresponds to a transmission scanning electron microscope but with addition of a gaseous environment acting both as environmental and detection medium. A commercial type of low vacuum machine has been employed together with appropriate modifications to the detection configuration. This involves controlled screening of various emitted signals in conjunction with a scintillation gaseous detection device already provided with the machine for regular surface imaging. Dark field and bright field imaging has been obtained along with other detection conditions. With a progressive series of modifications and tests, the theory and practice of a novel type of microscopy is briefly shown now ushering further significant improvements and developments in electron microscopy as a whole. Copyright © 2014 Elsevier B.V. All rights reserved.

Optofluidic bioimaging platform for quantitative phase imaging of lab on a chip devices using digital holographic microscopy.

PubMed

Pandiyan, Vimal Prabhu; John, Renu

2016-01-20

We propose a versatile 3D phase-imaging microscope platform for real-time imaging of optomicrofluidic devices based on the principle of digital holographic microscopy (DHM). Lab-on-chip microfluidic devices fabricated on transparent polydimethylsiloxane (PDMS) and glass substrates have attained wide popularity in biological sensing applications. However, monitoring, visualization, and characterization of microfluidic devices, microfluidic flows, and the biochemical kinetics happening in these devices is difficult due to the lack of proper techniques for real-time imaging and analysis. The traditional bright-field microscopic techniques fail in imaging applications, as the microfluidic channels and the fluids carrying biological samples are transparent and not visible in bright light. Phase-based microscopy techniques that can image the phase of the microfluidic channel and changes in refractive indices due to the fluids and biological samples present in the channel are ideal for imaging the fluid flow dynamics in a microfluidic channel at high resolutions. This paper demonstrates three-dimensional imaging of a microfluidic device with nanometric depth precisions and high SNR. We demonstrate imaging of microelectrodes of nanometric thickness patterned on glass substrate and the microfluidic channel. Three-dimensional imaging of a transparent PDMS optomicrofluidic channel, fluid flow, and live yeast cell flow in this channel has been demonstrated using DHM. We also quantify the average velocity of fluid flow through the channel. In comparison to any conventional bright-field microscope, the 3D depth information in the images illustrated in this work carry much information about the biological system under observation. The results demonstrated in this paper prove the high potential of DHM in imaging optofluidic devices; detection of pathogens, cells, and bioanalytes on lab-on-chip devices; and in studying microfluidic dynamics in real time based on phase changes.

Electron Source Brightness and Illumination Semi-Angle Distribution Measurement in a Transmission Electron Microscope.

PubMed

Börrnert, Felix; Renner, Julian; Kaiser, Ute

2018-05-21

The electron source brightness is an important parameter in an electron microscope. Reliable and easy brightness measurement routes are not easily found. A determination method for the illumination semi-angle distribution in transmission electron microscopy is even less well documented. Herein, we report a simple measurement route for both entities and demonstrate it on a state-of-the-art instrument. The reduced axial brightness of the FEI X-FEG with a monochromator was determined to be larger than 108 A/(m2 sr V).

Identification of malaria infected red blood samples by digital holographic quantitative phase microscope

NASA Astrophysics Data System (ADS)

Patel, Nimit R.; Chhaniwal, Vani K.; Javidi, Bahram; Anand, Arun

2015-07-01

Development of devices for automatic identification of diseases is desired especially in developing countries. In the case of malaria, even today the gold standard is the inspection of chemically treated blood smears through a microscope. This requires a trained technician/microscopist to identify the cells in the field of view, with which the labeling chemicals gets attached. Bright field microscopes provide only low contrast 2D images of red blood cells and cell thickness distribution cannot be obtained. Quantitative phase contrast microscopes can provide both intensity and phase profiles of the cells under study. The phase information can be used to determine thickness profile of the cell. Since cell morphology is available, many parameters pertaining to the 3D shape of the cell can be computed. These parameters in turn could be used to decide about the state of health of the cell leading to disease diagnosis. Here the investigations done on digital holographic microscope, which provides quantitative phase images, for comparison of parameters obtained from the 3D shape profile of objects leading to identification of diseased samples is described.

A Simple low-cost device enables four epi-illumination techniques on standard light microscopes.

PubMed

Ishmukhametov, Robert R; Russell, Aidan N; Wheeler, Richard J; Nord, Ashley L; Berry, Richard M

2016-02-08

Back-scattering darkfield (BSDF), epi-fluorescence (EF), interference reflection contrast (IRC), and darkfield surface reflection (DFSR) are advanced but expensive light microscopy techniques with limited availability. Here we show a simple optical design that combines these four techniques in a simple low-cost miniature epi-illuminator, which inserts into the differential interference-contrast (DIC) slider bay of a commercial microscope, without further additions required. We demonstrate with this device: 1) BSDF-based detection of Malarial parasites inside unstained human erythrocytes; 2) EF imaging with and without dichroic components, including detection of DAPI-stained Leishmania parasite without using excitation or emission filters; 3) RIC of black lipid membranes and other thin films, and 4) DFSR of patterned opaque and transparent surfaces. We believe that our design can expand the functionality of commercial bright field microscopes, provide easy field detection of parasites and be of interest to many users of light microscopy.

A Simple low-cost device enables four epi-illumination techniques on standard light microscopes

NASA Astrophysics Data System (ADS)

Ishmukhametov, Robert R.; Russell, Aidan N.; Wheeler, Richard J.; Nord, Ashley L.; Berry, Richard M.

2016-02-01

Back-scattering darkfield (BSDF), epi-fluorescence (EF), interference reflection contrast (IRC), and darkfield surface reflection (DFSR) are advanced but expensive light microscopy techniques with limited availability. Here we show a simple optical design that combines these four techniques in a simple low-cost miniature epi-illuminator, which inserts into the differential interference-contrast (DIC) slider bay of a commercial microscope, without further additions required. We demonstrate with this device: 1) BSDF-based detection of Malarial parasites inside unstained human erythrocytes; 2) EF imaging with and without dichroic components, including detection of DAPI-stained Leishmania parasite without using excitation or emission filters; 3) RIC of black lipid membranes and other thin films, and 4) DFSR of patterned opaque and transparent surfaces. We believe that our design can expand the functionality of commercial bright field microscopes, provide easy field detection of parasites and be of interest to many users of light microscopy.

Fabrication of a trimer/single atom tip for gas field ion sources by means of field evaporation without tip heating.

PubMed

Kim, Kwang-Il; Kim, Young Heon; Ogawa, Takashi; Choi, Suji; Cho, Boklae; Ahn, Sang Jung; Park, In-Yong

2018-05-11

A gas field ion source (GFIS) has many advantages that are suitable for ion microscope sources, such as high brightness and a small virtual source size, among others. In order to apply a tip-based GFIS to an ion microscope, it is better to create a trimer/single atom tip (TSAT), where the ion beam must be generated in several atoms of the tip apex. Here, unlike the conventional method which uses tip heating or a reactive gas, we show that the tip surface can be cleaned using only the field evaporation phenomenon and that the TSAT can also be fabricated using an insulating layer containing tungsten oxide, which remains after electrochemical etching. Using this method, we could get TSAT over 90% of yield. Copyright © 2018. Published by Elsevier B.V.

Use of astronomy filters in fluorescence microscopy.

PubMed

Piper, Jörg

2012-02-01

Monochrome astronomy filters are well suited for use as excitation or suppression filters in fluorescence microscopy. Because of their particular optical design, such filters can be combined with standard halogen light sources for excitation in many fluorescent probes. In this "low energy excitation," photobleaching (fading) or other irritations of native specimens are avoided. Photomicrographs can be taken from living motile fluorescent specimens also with a flash so that fluorescence images can be created free from indistinctness caused by movement. Special filter cubes or dichroic mirrors are not needed for our method. By use of suitable astronomy filters, fluorescence microscopy can be carried out with standard laboratory microscopes equipped with condensers for bright-field (BF) and dark-field (DF) illumination in transmitted light. In BF excitation, the background brightness can be modulated in tiny steps up to dark or black. Moreover, standard industry microscopes fitted with a vertical illuminator for examinations of opaque probes in DF or BF illumination based on incident light (wafer inspections, for instance) can also be used for excitation in epi-illumination when adequate astronomy filters are inserted as excitatory and suppression filters in the illuminating and imaging light path. In all variants, transmission bands can be modulated by transmission shift.

Fast and Adaptive Auto-focusing Microscope

NASA Astrophysics Data System (ADS)

Obara, Takeshi; Igarashi, Yasunobu; Hashimoto, Koichi

Optical microscopes are widely used in biological and medical researches. By using the microscope, we can observe cellular movements including intracellular ions and molecules tagged with fluorescent dyes at a high magnification. However, a freely motile cell easily escapes from a 3D field of view of the typical microscope. Therefore, we propose a novel auto-focusing algorithm and develop a auto-focusing and tracking microscope. XYZ positions of a microscopic stage are feedback controlled to focus and track the cell automatically. A bright-field image is used to estimate a cellular position. XY centroids are used to estimate XY positions of the tracked cell. To estimate Z position, we use a diffraction pattern around the cell membrane. This estimation method is so-called Depth from Diffraction (DFDi). However, this method is not robust for individual differences between cells because the diffraction pattern depends on each cellular shape. Therefore, in this study, we propose a real-time correction of DFDi by using 2D Laplacian of an intracellular area as a goodness of the focus. To evaluate the performance of our developed algorithm and microscope, we auto-focus and track a freely moving paramecium. In this experimental result, the paramecium is auto-focused and kept inside the scope of the microscope during 45s. The evaluated focal error is within 5µm, while a length and a thickness of the paramecium are about 200µm and 50µm, respectively.

Microscopic validation of whole mouse micro-metastatic tumor imaging agents using cryo-imaging and sliding organ image registration.

PubMed

Liu, Yiqiao; Zhou, Bo; Qutaish, Mohammed; Wilson, David L

2016-01-01

We created a metastasis imaging, analysis platform consisting of software and multi-spectral cryo-imaging system suitable for evaluating emerging imaging agents targeting micro-metastatic tumor. We analyzed CREKA-Gd in MRI, followed by cryo-imaging which repeatedly sectioned and tiled microscope images of the tissue block face, providing anatomical bright field and molecular fluorescence, enabling 3D microscopic imaging of the entire mouse with single metastatic cell sensitivity. To register MRI volumes to the cryo bright field reference, we used our standard mutual information, non-rigid registration which proceeded: preprocess → affine → B-spline non-rigid 3D registration. In this report, we created two modified approaches: mask where we registered locally over a smaller rectangular solid, and sliding organ . Briefly, in sliding organ , we segmented the organ, registered the organ and body volumes separately and combined results. Though s liding organ required manual annotation, it provided the best result as a standard to measure other registration methods. Regularization parameters for standard and mask methods were optimized in a grid search. Evaluations consisted of DICE, and visual scoring of a checkerboard display. Standard had accuracy of 2 voxels in all regions except near the kidney, where there were 5 voxels sliding. After mask and sliding organ correction, kidneys sliding were within 2 voxels, and Dice overlap increased 4%-10% in mask compared to standard . Mask generated comparable results with sliding organ and allowed a semi-automatic process.

Microscopic validation of whole mouse micro-metastatic tumor imaging agents using cryo-imaging and sliding organ image registration

NASA Astrophysics Data System (ADS)

Liu, Yiqiao; Zhou, Bo; Qutaish, Mohammed; Wilson, David L.

2016-03-01

We created a metastasis imaging, analysis platform consisting of software and multi-spectral cryo-imaging system suitable for evaluating emerging imaging agents targeting micro-metastatic tumor. We analyzed CREKA-Gd in MRI, followed by cryo-imaging which repeatedly sectioned and tiled microscope images of the tissue block face, providing anatomical bright field and molecular fluorescence, enabling 3D microscopic imaging of the entire mouse with single metastatic cell sensitivity. To register MRI volumes to the cryo bright field reference, we used our standard mutual information, non-rigid registration which proceeded: preprocess --> affine --> B-spline non-rigid 3D registration. In this report, we created two modified approaches: mask where we registered locally over a smaller rectangular solid, and sliding organ. Briefly, in sliding organ, we segmented the organ, registered the organ and body volumes separately and combined results. Though sliding organ required manual annotation, it provided the best result as a standard to measure other registration methods. Regularization parameters for standard and mask methods were optimized in a grid search. Evaluations consisted of DICE, and visual scoring of a checkerboard display. Standard had accuracy of 2 voxels in all regions except near the kidney, where there were 5 voxels sliding. After mask and sliding organ correction, kidneys sliding were within 2 voxels, and Dice overlap increased 4%-10% in mask compared to standard. Mask generated comparable results with sliding organ and allowed a semi-automatic process.

Authentication of bee pollen grains in bright-field microscopy by combining one-class classification techniques and image processing.

PubMed

Chica, Manuel

2012-11-01

A novel method for authenticating pollen grains in bright-field microscopic images is presented in this work. The usage of this new method is clear in many application fields such as bee-keeping sector, where laboratory experts need to identify fraudulent bee pollen samples against local known pollen types. Our system is based on image processing and one-class classification to reject unknown pollen grain objects. The latter classification technique allows us to tackle the major difficulty of the problem, the existence of many possible fraudulent pollen types, and the impossibility of modeling all of them. Different one-class classification paradigms are compared to study the most suitable technique for solving the problem. In addition, feature selection algorithms are applied to reduce the complexity and increase the accuracy of the models. For each local pollen type, a one-class classifier is trained and aggregated into a multiclassifier model. This multiclassification scheme combines the output of all the one-class classifiers in a unique final response. The proposed method is validated by authenticating pollen grains belonging to different Spanish bee pollen types. The overall accuracy of the system on classifying fraudulent microscopic pollen grain objects is 92.3%. The system is able to rapidly reject pollen grains, which belong to nonlocal pollen types, reducing the laboratory work and effort. The number of possible applications of this authentication method in the microscopy research field is unlimited. Copyright © 2012 Wiley Periodicals, Inc.

Scanning Transmission Electron Microscopy at High Resolution

PubMed Central

Wall, J.; Langmore, J.; Isaacson, M.; Crewe, A. V.

1974-01-01

We have shown that a scanning transmission electron microscope with a high brightness field emission source is capable of obtaining better than 3 Å resolution using 30 to 40 keV electrons. Elastic dark field images of single atoms of uranium and mercury are shown which demonstrate this fact as determined by a modified Rayleigh criterion. Point-to-point micrograph resolution between 2.5 and 3.0 Å is found in dark field images of micro-crystallites of uranium and thorium compounds. Furthermore, adequate contrast is available to observe single atoms as light as silver. Images PMID:4521050

Dual-modal three-dimensional imaging of single cells with isometric high resolution using an optical projection tomography microscope

NASA Astrophysics Data System (ADS)

Miao, Qin; Rahn, J. Richard; Tourovskaia, Anna; Meyer, Michael G.; Neumann, Thomas; Nelson, Alan C.; Seibel, Eric J.

2009-11-01

The practice of clinical cytology relies on bright-field microscopy using absorption dyes like hematoxylin and eosin in the transmission mode, while the practice of research microscopy relies on fluorescence microscopy in the epi-illumination mode. The optical projection tomography microscope is an optical microscope that can generate 3-D images of single cells with isometric high resolution both in absorption and fluorescence mode. Although the depth of field of the microscope objective is in the submicron range, it can be extended by scanning the objective's focal plane. The extended depth of field image is similar to a projection in a conventional x-ray computed tomography. Cells suspended in optical gel flow through a custom-designed microcapillary. Multiple pseudoprojection images are taken by rotating the microcapillary. After these pseudoprojection images are further aligned, computed tomography methods are applied to create 3-D reconstruction. 3-D reconstructed images of single cells are shown in both absorption and fluorescence mode. Fluorescence spatial resolution is measured at 0.35 μm in both axial and lateral dimensions. Since fluorescence and absorption images are taken in two different rotations, mechanical error may cause misalignment of 3-D images. This mechanical error is estimated to be within the resolution of the system.

High-resolution scanning precession electron diffraction: Alignment and spatial resolution.

PubMed

Barnard, Jonathan S; Johnstone, Duncan N; Midgley, Paul A

2017-03-01

Methods are presented for aligning the pivot point of a precessing electron probe in the scanning transmission electron microscope (STEM) and for assessing the spatial resolution in scanning precession electron diffraction (SPED) experiments. The alignment procedure is performed entirely in diffraction mode, minimising probe wander within the bright-field (BF) convergent beam electron diffraction (CBED) disk and is used to obtain high spatial resolution SPED maps. Through analysis of the power spectra of virtual bright-field images extracted from the SPED data, the precession-induced blur was measured as a function of precession angle. At low precession angles, SPED spatial resolution was limited by electronic noise in the scan coils; whereas at high precession angles SPED spatial resolution was limited by tilt-induced two-fold astigmatism caused by the positive spherical aberration of the probe-forming lens. Copyright © 2016 Elsevier B.V. All rights reserved.

Imaging and identification of waterborne parasites using a chip-scale microscope.

PubMed

Lee, Seung Ah; Erath, Jessey; Zheng, Guoan; Ou, Xiaoze; Willems, Phil; Eichinger, Daniel; Rodriguez, Ana; Yang, Changhuei

2014-01-01

We demonstrate a compact portable imaging system for the detection of waterborne parasites in resource-limited settings. The previously demonstrated sub-pixel sweeping microscopy (SPSM) technique is a lens-less imaging scheme that can achieve high-resolution (<1 µm) bright-field imaging over a large field-of-view (5.7 mm×4.3 mm). A chip-scale microscope system, based on the SPSM technique, can be used for automated and high-throughput imaging of protozoan parasite cysts for the effective diagnosis of waterborne enteric parasite infection. We successfully imaged and identified three major types of enteric parasite cysts, Giardia, Cryptosporidium, and Entamoeba, which can be found in fecal samples from infected patients. We believe that this compact imaging system can serve well as a diagnostic device in challenging environments, such as rural settings or emergency outbreaks.

Using Cell-ID 1.4 with R for Microscope-Based Cytometry

PubMed Central

Bush, Alan; Chernomoretz, Ariel; Yu, Richard; Gordon, Andrew

2012-01-01

This unit describes a method for quantifying various cellular features (e.g., volume, total and subcellular fluorescence localization) from sets of microscope images of individual cells. It includes procedures for tracking cells over time. One purposefully defocused transmission image (sometimes referred to as bright-field or BF) is acquired to segment the image and locate each cell. Fluorescent images (one for each of the color channels to be analyzed) are then acquired by conventional wide-field epifluorescence or confocal microscopy. This method uses the image processing capabilities of Cell-ID (Gordon et al., 2007, as updated here) and data analysis by the statistical programming framework R (R-Development-Team, 2008), which we have supplemented with a package of routines for analyzing Cell-ID output. Both Cell-ID and the analysis package are open-source. PMID:23026908

Use of a night vision intensifier for direct visualization by eye of far-red and near-infrared fluorescence through an optical microscope.

PubMed

Siddiqi, M A; Kilduff, G M; Gearhart, J D

2003-11-01

We describe the design, construction and testing of a prototype device that allows the direct visualization by eye of far-red and near-infrared (NIR) fluorescence through an optical microscope. The device incorporates a gallium arsenide (GaAs) image intensifier, typically utilized in low-light or 'night vision' applications. The intensifier converts far-red and NIR light into electrons and then into green light, which is visible to the human eye. The prototype makes possible the direct, real-time viewing by eye of normally invisible far-red and NIR fluorescence from a wide variety of fluorophores, using the full field of view of the microscope to which it is applied. The high sensitivity of the image intensifier facilitates the viewing of a wide variety of photosensitive specimens, including live cells and embryos, at vastly reduced illumination levels in both fluorescence and bright-field microscopy. Modifications to the microscope are not required in order to use the prototype, which is fully compatible with all current fluorescence techniques. Refined versions of the prototype device will have broad research and clinical applications.

High-pressure freezing for scanning transmission electron tomography analysis of cellular organelles.

PubMed

Walther, Paul; Schmid, Eberhard; Höhn, Katharina

2013-01-01

Using an electron microscope's scanning transmission mode (STEM) for collection of tomographic datasets is advantageous compared to bright field transmission electron microscopic (TEM). For image formation, inelastic scattering does not cause chromatic aberration, since in STEM mode no image forming lenses are used after the beam has passed the sample, in contrast to regular TEM. Therefore, thicker samples can be imaged. It has been experimentally demonstrated that STEM is superior to TEM and energy filtered TEM for tomography of samples as thick as 1 μm. Even when using the best electron microscope, adequate sample preparation is the key for interpretable results. We adapted protocols for high-pressure freezing of cultivated cells from a physiological state. In this chapter, we describe optimized high-pressure freezing and freeze substitution protocols for STEM tomography in order to obtain high membrane contrast.

Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope.

PubMed

den Engelsen, Daniel; Harris, Paul G; Ireland, Terry G; Fern, George R; Silver, Jack

2015-10-01

Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. Copyright © 2015 Elsevier B.V. All rights reserved.

New solutions for standardization, monitoring and quality management of fluorescence-based imaging systems (Conference Presentation)

NASA Astrophysics Data System (ADS)

Royon, Arnaud; Papon, Gautier

2016-03-01

Fluorescence microscopes have become ubiquitous in life sciences laboratories, including those focused on pharmaceuticals, diagnosis, and forensics. For the past few years, the need for both performance guarantees and quantifiable results has driven development in this area. However, the lack of appropriate standards and reference materials makes it difficult or impossible to compare the results of two fluorescence microscopes, or to measure performance fluctuations of one microscope over time. Therefore, the operation of fluorescence microscopes is not monitored as often as their use warrants - an issue that is recognized by both systems manufacturers and national metrology institutes. We have developed a new process that enables the etching of long-term stable fluorescent patterns with sub-micrometer sizes in three dimensions inside glass. In this paper, we present, based on this new process, a fluorescent multi-dimensional ruler and a dedicated software that are suitable for monitoring and quality management of fluorescence-based imaging systems (wide-field, confocal, multiphoton, high content machines). In addition to fluorescence, the same patterns exhibit bright- and dark-field contrast, DIC, and phase contrast, which make them also relevant to monitor these types of microscopes. Non-exhaustively, this new solution enables the measurement of: The stage repositioning accuracy; The illumination and detection homogeneities; The field flatness; The detectors' characteristics; The lateral and axial spatial resolutions; The spectral response (spectrum, intensity and lifetime) of the system. Thanks to the stability of the patterns, microscope performance assessment can be carried out as well in a daily basis as in the long term.

Mirrored pyramidal wells for simultaneous multiple vantage point microscopy.

PubMed

Seale, K T; Reiserer, R S; Markov, D A; Ges, I A; Wright, C; Janetopoulos, C; Wikswo, J P

2008-10-01

We report a novel method for obtaining simultaneous images from multiple vantage points of a microscopic specimen using size-matched microscopic mirrors created from anisotropically etched silicon. The resulting pyramidal wells enable bright-field and fluorescent side-view images, and when combined with z-sectioning, provide additional information for 3D reconstructions of the specimen. We have demonstrated the 3D localization and tracking over time of the centrosome of a live Dictyostelium discoideum. The simultaneous acquisition of images from multiple perspectives also provides a five-fold increase in the theoretical collection efficiency of emitted photons, a property which may be useful for low-light imaging modalities such as bioluminescence, or low abundance surface-marker labelling.

The Wavelength-Dispersive Spectrometer and Its Proposed Use in the Analytical Electron Microscope

NASA Technical Reports Server (NTRS)

Goldstein, Joseph I.; Lyman, Charles E.; Williams, David B.

1989-01-01

The Analytical Electron Microscope (AEM) equipped with a wavelength-dispersive spectrometer (WDS) should have the ability to resolve peaks which normally overlap in the spectra from an energy-dispersive spectrometer (EDS). With a WDS it should also be possible to measure lower concentrations of elements in thin foils due to the increased peak-to-background ratio compared with EDS. The WDS will measure X-ray from the light elements (4 less than Z less than 1O) more effectively. This paper addresses the possibility of interfacing a compact WDS with a focussing circle of approximately 4 cm to a modem AEM with a high-brightness (field emission) source of electrons.

High spatial resolution and high brightness ion beam probe for in-situ elemental and isotopic analysis

NASA Astrophysics Data System (ADS)

Long, Tao; Clement, Stephen W. J.; Bao, Zemin; Wang, Peizhi; Tian, Di; Liu, Dunyi

2018-03-01

A high spatial resolution and high brightness ion beam from a cold cathode duoplasmatron source and primary ion optics are presented and applied to in-situ analysis of micro-scale geological material with complex structural and chemical features. The magnetic field in the source as well as the influence of relative permeability of magnetic materials on source performance was simulated using COMSOL to confirm the magnetic field strength of the source. Based on SIMION simulation, a high brightness and high spatial resolution negative ion optical system has been developed to achieve Critical (Gaussian) illumination mode. The ion source and primary column are installed on a new Time-of-Flight secondary ion mass spectrometer for analysis of geological samples. The diameter of the ion beam was measured by the knife-edge method and a scanning electron microscope (SEM). Results show that an O2- beam of ca. 5 μm diameter with a beam intensity of ∼5 nA and an O- beam of ca. 5 μm diameter with a beam intensity of ∼50 nA were obtained, respectively. This design will open new possibilities for in-situ elemental and isotopic analysis in geological studies.

Angularly-selective transmission imaging in a scanning electron microscope.

PubMed

Holm, Jason; Keller, Robert R

2016-08-01

This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed. Published by Elsevier B.V.

Mirrored pyramidal wells for simultaneous multiple vantage point microscopy

PubMed Central

Seale, K.T.; Reiserer, R.S.; Markov, D.A.; Ges, I.A.; Wright, C.; Janetopoulos, C.; Wikswo, J.P.

2013-01-01

Summary We report a novel method for obtaining simultaneous images from multiple vantage points of a microscopic specimen using size-matched microscopic mirrors created from anisotropically etched silicon. The resulting pyramidal wells enable bright-field and fluorescent side-view images, and when combined with z-sectioning, provide additional information for 3D reconstructions of the specimen. We have demonstrated the 3D localization and tracking over time of the centrosome of a live Dictyostelium discoideum. The simultaneous acquisition of images from multiple perspectives also provides a five-fold increase in the theoretical collection efficiency of emitted photons, a property which may be useful for low-light imaging modalities such as bioluminescence, or low abundance surface-marker labelling. PMID:19017196

Autofocus algorithm using one-dimensional Fourier transform and Pearson correlation

NASA Astrophysics Data System (ADS)

Bueno Mario, A.; Alvarez-Borrego, Josue; Acho, L.

2004-10-01

A new autofocus algorithm based on one-dimensional Fourier transform and Pearson correlation for Z automatized microscope is proposed. Our goal is to determine in fast response time and accuracy, the best focused plane through an algorithm. We capture in bright and dark field several images set at different Z distances from biological organism sample. The algorithm uses the one-dimensional Fourier transform to obtain the image frequency content of a vectors pattern previously defined comparing the Pearson correlation of these frequency vectors versus the reference image frequency vector, the most out of focus image, we find the best focusing. Experimental results showed the algorithm has fast response time and accuracy in getting the best focus plane from captured images. In conclusions, the algorithm can be implemented in real time systems due fast response time, accuracy and robustness. The algorithm can be used to get focused images in bright and dark field and it can be extended to include fusion techniques to construct multifocus final images beyond of this paper.

Nanosurveyor: a framework for real-time data processing

DOE PAGES

Daurer, Benedikt J.; Krishnan, Hari; Perciano, Talita; ...

2017-01-31

Background: The ever improving brightness of accelerator based sources is enabling novel observations and discoveries with faster frame rates, larger fields of view, higher resolution, and higher dimensionality. Results: Here we present an integrated software/algorithmic framework designed to capitalize on high-throughput experiments through efficient kernels, load-balanced workflows, which are scalable in design. We describe the streamlined processing pipeline of ptychography data analysis. Conclusions: The pipeline provides throughput, compression, and resolution as well as rapid feedback to the microscope operators.

Fluorescence correlation spectroscopy, Raster image correlation spectroscopy and Number & Brightness on a commercial confocal laser scanning microscope with analog detectors (Nikon C1)

PubMed Central

Moens, Pierre D.J.; Gratton, Enrico; Salvemini, Iyrri L.

2010-01-01

Fluorescence correlation spectroscopy (FCS) was developed in 1972 by Magde, Elson and Webb (Magde et al., 1972). Photon counting detectors and avalanche photodiodes have become standards in FCS to the point that there is a widespread belief that these detectors are essential to perform FCS experiments, despite the fact that FCS was developed using analog detectors. Spatial and temporal intensity fluctuation correlations using analog detection on a commercial Olympus Fluoview 300 microscope has been reported by Brown et al. (2008). However, each analog instrument has its own idiosyncrasies that need to be understood before using the instrument for FCS. In this work we explore the capabilities of the Nikon C1, a low cost confocal microscope, to obtain single point FCS, Raster-scan Image Correlation Spectroscopy (RICS) and Number & Brightness data both in solution and incorporated into the membrane of Giant Unilamellar Vesicles (GUVs). We show that it is possible to obtain dynamic information about fluorescent molecules from single point FCS, RICS and Number & Brightness using the Nikon C1. We highlighted the fact that care should be taken in selecting the acquisition parameters in order to avoid possible artifacts due to the detector noise. However, due to relatively large errors in determining the distribution of digital levels for a given microscope setting, the system is probably only adequate for determining relative brightness within the same image. PMID:20734406

Whole-cell imaging of the budding yeast Saccharomyces cerevisiae by high-voltage scanning transmission electron tomography.

PubMed

Murata, Kazuyoshi; Esaki, Masatoshi; Ogura, Teru; Arai, Shigeo; Yamamoto, Yuta; Tanaka, Nobuo

2014-11-01

Electron tomography using a high-voltage electron microscope (HVEM) provides three-dimensional information about cellular components in sections thicker than 1 μm, although in bright-field mode image degradation caused by multiple inelastic scattering of transmitted electrons limit the attainable resolution. Scanning transmission electron microscopy (STEM) is believed to give enhanced contrast and resolution compared to conventional transmission electron microscopy (CTEM). Samples up to 1 μm in thickness have been analyzed with an intermediate-voltage electron microscope because inelastic scattering is not a critical limitation, and probe broadening can be minimized. Here, we employed STEM at 1 MeV high-voltage to extend the useful specimen thickness for electron tomography, which we demonstrate by a seamless tomographic reconstruction of a whole, budding Saccharomyces cerevisiae yeast cell, which is ~3 μm in thickness. High-voltage STEM tomography, especially in the bright-field mode, demonstrated sufficiently enhanced contrast and intensity, compared to CTEM tomography, to permit segmentation of major organelles in the whole cell. STEM imaging also reduced specimen shrinkage during tilt-series acquisition. The fidelity of structural preservation was limited by cytoplasmic extraction, and the spatial resolution was limited by the relatively large convergence angle of the scanning probe. However, the new technique has potential to solve longstanding problems of image blurring in biological specimens beyond 1 μm in thickness, and may facilitate new research in cellular structural biology. Copyright © 2014 Elsevier B.V. All rights reserved.

Photonic-crystal membranes for optical detection of single nano-particles, designed for biosensor application.

PubMed

Grepstad, Jon Olav; Kaspar, Peter; Solgaard, Olav; Johansen, Ib-Rune; Sudbø, Aasmund S

2012-03-26

A sensor designed to detect bio-molecules is presented. The sensor exploits a planar 2D photonic crystal (PC) membrane with sub-micron thickness and through holes, to induce high optical fields that allow detection of nano-particles smaller than the diffraction limit of an optical microscope. We report on our design and fabrication of a PC membrane with a nano-particle trapped inside. We have also designed and built an imaging system where an optical microscope and a CCD camera are used to take images of the PC membrane. Results show how the trapped nano-particle appears as a bright spot in the image. In a first experimental realization of the imaging system, single particles with a radius of 75 nm can be detected.

Selective colors reflection from stratified aragonite calcium carbonate plates of mollusk shells.

PubMed

Lertvachirapaiboon, Chutiparn; Parnklang, Tewarak; Pienpinijtham, Prompong; Wongravee, Kanet; Thammacharoen, Chuchaat; Ekgasit, Sanong

2015-08-01

An interaction between the incident light and the structural architecture within the shell of Asian green mussel (Perna viridis) induces observable pearlescent colors. In this paper, we investigate the influence of the structural architecture on the expressed colors. After a removal of the organic binder, small flakes from crushed shells show vivid rainbow reflection under an optical microscope. An individual flake expresses vivid color under a bright-field illumination while become transparent under a dark-field illumination. The expressed colors of the aragonite flakes are directly associated with its structural architecture. The flakes with aragonite thickness of 256, 310, and 353 nm, respectively, appear blue, green, and red under an optical microscope. The spectral simulation corroborates the experimentally observed optical effects as the flakes with thicker aragonite layers selectively reflected color with longer wavelengths. Flakes with multiple aragonite thicknesses expressed multi-color as the upper aragonite layers allow reflected colors from the lower layers to be observed. Copyright © 2015 Elsevier Inc. All rights reserved.

Two-dimensional tracking of a motile micro-organism allowing high-resolution observation with various imaging techniques

NASA Astrophysics Data System (ADS)

Oku, H.; Ogawa, N.; Ishikawa, M.; Hashimoto, K.

2005-03-01

In this article, a micro-organism tracking system using a high-speed vision system is reported. This system two dimensionally tracks a freely swimming micro-organism within the field of an optical microscope by moving a chamber of target micro-organisms based on high-speed visual feedback. The system we developed could track a paramecium using various imaging techniques, including bright-field illumination, dark-field illumination, and differential interference contrast, at magnifications of 5 times and 20 times. A maximum tracking duration of 300s was demonstrated. Also, the system could track an object with a velocity of up to 35 000μm/s (175diameters/s), which is significantly faster than swimming micro-organisms.

Easy monitoring of velocity fields in microfluidic devices using spatiotemporal image correlation spectroscopy.

PubMed

Travagliati, Marco; Girardo, Salvatore; Pisignano, Dario; Beltram, Fabio; Cecchini, Marco

2013-09-03

Spatiotemporal image correlation spectroscopy (STICS) is a simple and powerful technique, well established as a tool to probe protein dynamics in cells. Recently, its potential as a tool to map velocity fields in lab-on-a-chip systems was discussed. However, the lack of studies on its performance has prevented its use for microfluidics applications. Here, we systematically and quantitatively explore STICS microvelocimetry in microfluidic devices. We exploit a simple experimental setup, based on a standard bright-field inverted microscope (no fluorescence required) and a high-fps camera, and apply STICS to map liquid flow in polydimethylsiloxane (PDMS) microchannels. Our data demonstrates optimal 2D velocimetry up to 10 mm/s flow and spatial resolution down to 5 μm.

Source brightness and useful beam current of carbon nanotubes and other very small emitters

NASA Astrophysics Data System (ADS)

Kruit, P.; Bezuijen, M.; Barth, J. E.

2006-01-01

The potential application of carbon nanotubes as electron sources in electron microscopes is analyzed. The resolution and probe current that can be obtained from a carbon nanotube emitter in a low-voltage scanning electron microscope are calculated and compared to the state of the art using Schottky electron sources. Many analytical equations for probe-size versus probe-current relations in different parameter regimes are obtained. It is shown that for most carbon nanotube emitters, the gun lens aberrations are larger than the emitters' virtual source size and thus restrict the microscope's performance. The result is that the advantages of the higher brightness of nanotube emitters are limited unless the angular emission current is increased over present day values or the gun lens aberrations are decreased. For some nanotubes with a closed cap, it is known that the emitted electron beam is coherent over the full emission cone. We argue that for such emitters the parameter ``brightness'' becomes meaningless. The influence of phase variations in the electron wave front emitted from such a nanotube emitter on the focusing of the electron beam is analyzed.

Nanometric depth resolution from multi-focal images in microscopy.

PubMed

Dalgarno, Heather I C; Dalgarno, Paul A; Dada, Adetunmise C; Towers, Catherine E; Gibson, Gavin J; Parton, Richard M; Davis, Ilan; Warburton, Richard J; Greenaway, Alan H

2011-07-06

We describe a method for tracking the position of small features in three dimensions from images recorded on a standard microscope with an inexpensive attachment between the microscope and the camera. The depth-measurement accuracy of this method is tested experimentally on a wide-field, inverted microscope and is shown to give approximately 8 nm depth resolution, over a specimen depth of approximately 6 µm, when using a 12-bit charge-coupled device (CCD) camera and very bright but unresolved particles. To assess low-flux limitations a theoretical model is used to derive an analytical expression for the minimum variance bound. The approximations used in the analytical treatment are tested using numerical simulations. It is concluded that approximately 14 nm depth resolution is achievable with flux levels available when tracking fluorescent sources in three dimensions in live-cell biology and that the method is suitable for three-dimensional photo-activated localization microscopy resolution. Sub-nanometre resolution could be achieved with photon-counting techniques at high flux levels.

Nanometric depth resolution from multi-focal images in microscopy

PubMed Central

Dalgarno, Heather I. C.; Dalgarno, Paul A.; Dada, Adetunmise C.; Towers, Catherine E.; Gibson, Gavin J.; Parton, Richard M.; Davis, Ilan; Warburton, Richard J.; Greenaway, Alan H.

2011-01-01

We describe a method for tracking the position of small features in three dimensions from images recorded on a standard microscope with an inexpensive attachment between the microscope and the camera. The depth-measurement accuracy of this method is tested experimentally on a wide-field, inverted microscope and is shown to give approximately 8 nm depth resolution, over a specimen depth of approximately 6 µm, when using a 12-bit charge-coupled device (CCD) camera and very bright but unresolved particles. To assess low-flux limitations a theoretical model is used to derive an analytical expression for the minimum variance bound. The approximations used in the analytical treatment are tested using numerical simulations. It is concluded that approximately 14 nm depth resolution is achievable with flux levels available when tracking fluorescent sources in three dimensions in live-cell biology and that the method is suitable for three-dimensional photo-activated localization microscopy resolution. Sub-nanometre resolution could be achieved with photon-counting techniques at high flux levels. PMID:21247948

Multicolor fluorescence microscopic imaging of cancer cells on the plasmonic chip (Presentation Recording)

NASA Astrophysics Data System (ADS)

Tawa, Keiko; Sasakawa, Chisato; Yamamura, Shohei; Shibata, Izumi; Kataoka, Masatoshi

2015-09-01

A plasmonic chip which is a metal coated substrate with grating structure can provide the enhanced fluorescence by the grating-coupled surface plasmon field. In our previous studies, bright epi-fluorescence microscopic imaging of neuron cells and sensitive immunosesnsing have been reported. In this study, two kinds of breast cancer cells, MCF-7 and MDA-MB231, were observed with epi-fluorescence microscope on the plasmonic chip with 2D hole-arrays . They were multicolor stained with 4', 6-diamidino-2-phenylindole (DAPI) and allophycocyanin (APC)-labeled anti-epithelial cell adhesion molecule (EpCAM) antibody. Our plasmonic chip provided the brighter fluorescence images of these cells compared with the glass slide. Even in the cells including few EpCAM, the distribution of EpCAM was clearly observed in the cell membrane. It was found that the plasmonic chip can be one of the powerful tools to detect the marker protein existing around the chip surface even at low concentration.

New poly(butylene succinate)/layered silicate nanocomposites: preparation and mechanical properties.

PubMed

Ray, Suprakas Sinha; Okamoto, Kazuaki; Maiti, Pralay; Okamoto, Masami

2002-04-01

New poly(butylene succinate) (PBS)/layered silicate nanocomposites have been successfully prepared by simple melt extrusion of PBS and octadecylammonium modified montmorillonite (C18-mmt) at 150 degrees C. The d-spacing of both C18-mmt and intercalated nanocomposites was investigated by wide-angle X-ray diffraction analysis. Bright-field transmission electron microscopic study showed several stacked silicate layers with random orientation in the PBS matrix. The intercalated nanocomposites exhibited remarkable improvement of mechanical properties in both solid and melt states as compared with that of PBS matrix without clay.

Fluorescence intensity and bright spot analyses using a confocal microscope for photodynamic diagnosis of brain tumors.

PubMed

Yoneyama, Takeshi; Watanabe, Tetsuyo; Kagawa, Hiroyuki; Hayashi, Yutaka; Nakada, Mitsutoshi

2017-03-01

In photodynamic diagnosis using 5-aminolevulinic acid (5-ALA), discrimination between the tumor and normal tissue is very important for a precise resection. However, it is difficult to distinguish between infiltrating tumor and normal regions in the boundary area. In this study, fluorescent intensity and bright spot analyses using a confocal microscope is proposed for the precise discrimination between infiltrating tumor and normal regions. From the 5-ALA-resected brain tumor tissue, the red fluorescent and marginal regions were sliced for observation under a confocal microscope. Hematoxylin and eosin (H&E) staining were performed on serial slices of the same tissue. According to the pathological inspection of the H&E slides, the tumor and infiltrating and normal regions on confocal microscopy images were investigated. From the fluorescent intensity of the image pixels, a histogram of pixel number with the same fluorescent intensity was obtained. The fluorescent bright spot sizes and total number were compared between the marginal and normal regions. The fluorescence intensity distribution and average intensity in the tumor were different from those in the normal region. The probability of a difference from the dark enhanced the difference between the tumor and the normal region. The bright spot size and number in the infiltrating tumor were different from those in the normal region. Fluorescence intensity analysis is useful to distinguish a tumor region, and a bright spot analysis is useful to distinguish between infiltrating tumor and normal regions. These methods will be important for the precise resection or photodynamic therapy of brain tumors. Copyright © 2016 Elsevier B.V. All rights reserved.

Bright-field electron tomography of individual inorganic fullerene-like structures.

PubMed

Bar Sadan, Maya; Wolf, Sharon G; Houben, Lothar

2010-03-01

Nanotubes and fullerene-like nanoparticles of various inorganic layered compounds have been studied extensively in recent years. Their characterisation on the atomic scale has proven essential for progress in synthesis as well as for the theoretical modelling of their physical properties. We show that with electron tomography it is possible to achieve a reliable reconstruction of the 3D structure of nested WS(2) or MoS(2) fullerene-like and nanotube structures with sub-nanometre resolution using electron microscopes that are not aberration-corrected. Model-based simulations were used to identify imaging parameters, under which structural features such as the shell structure can be retained in the tomogram reconstructed from bright-field micrographs. The isolation of a particle out of an agglomerate for the analysis of a single structure and its interconnection with other particles is facilitated through the tomograms. The internal structure of the layers within the particle alongside the shape and content of its internal void are reconstructed. The tomographic reconstruction yields insights regarding the growth process as well as structural defects, such as non-continuous layers, which relate to the lubrication properties.

Transmissive Nanohole Arrays for Massively-Parallel Optical Biosensing

PubMed Central

2015-01-01

A high-throughput optical biosensing technique is proposed and demonstrated. This hybrid technique combines optical transmission of nanoholes with colorimetric silver staining. The size and spacing of the nanoholes are chosen so that individual nanoholes can be independently resolved in massive parallel using an ordinary transmission optical microscope, and, in place of determining a spectral shift, the brightness of each nanohole is recorded to greatly simplify the readout. Each nanohole then acts as an independent sensor, and the blocking of nanohole optical transmission by enzymatic silver staining defines the specific detection of a biological agent. Nearly 10000 nanoholes can be simultaneously monitored under the field of view of a typical microscope. As an initial proof of concept, biotinylated lysozyme (biotin-HEL) was used as a model analyte, giving a detection limit as low as 0.1 ng/mL. PMID:25530982

Comparison of the structure of floral nectaries in two Euonymus L. species (Celastraceae).

PubMed

Konarska, Agata

2015-05-01

The inconspicuous Euonymus L. flowers are equipped with open receptacular floral nectaries forming a quadrilateral green disc around the base of the superior ovary. The morphology and anatomy of the nectaries in Euonymus fortunei (Turcz.) Hand.-Mazz. and Euonymus europaeus L. flowers were analysed under a bright-field light microscope as well as stereoscopic and scanning electron microscopes. Photosynthetic nectaries devoid of the vascular tissue were found in both species. Nectar was exuded through typical nectarostomata (E. fortunei) or nectarostomata and secretory cell cuticle (E. europaeus). The nectaries of the examined species differed in their width and height, number of layers and thickness of secretory parenchyma, and the height of epidermal cells. Moreover, there were differences in the location and abundance of nectarostomata and the content of starch and phenolic compounds.

Subwavelenght Light Localization in Nanostructured Surfaces

NASA Astrophysics Data System (ADS)

Coello, V.; Wang, S.; Siqueiros, J.; Bozhevolnyi, S. I.

Using a photon scanning tunneling microscope, we studied near field optical images obtained with a surface plasmon polariton (SPP) being resonantly excited along a surface with a random introduced roughness. The SPP intensity field distributions showed an optical enhancement in the form of round bright spots up to 5 times larger than the background signal. We also show an artificially fabricated SPP curved micromirror along with the corresponding near-field optical image. The recorded optical signal exhibited an enhancement up to 10 times larger than the background, which has been generated for the first time in a controlled form. A numerical simulation of a parabolic micromirror based on isotropic pointlike scatterers is analyzed and compared with experimental results. The potential of creating microstructures able to control SPP optical field enhancement is showed in a novel numerically simulated microcavity for SPP's.

Fabrication of bright and thin Zn₂SiO₄ luminescent film for electron beam excitation-assisted optical microscope.

PubMed

Furukawa, Taichi; Kanamori, Satoshi; Fukuta, Masahiro; Nawa, Yasunori; Kominami, Hiroko; Nakanishi, Yoichiro; Sugita, Atsushi; Inami, Wataru; Kawata, Yoshimasa

2015-07-13

We fabricated a bright and thin Zn₂SiO₄ luminescent film to serve as a nanometric light source for high-spatial-resolution optical microscopy based on electron beam excitation. The Zn₂SiO₄ luminescent thin film was fabricated by annealing a ZnO film on a Si₃N₄ substrate at 1000 °C in N₂. The annealed film emitted bright cathodoluminescence compared with the as-deposited film. The film is promising for nano-imaging with electron beam excitation-assisted optical microscopy. We evaluated the spatial resolution of a microscope developed using this Zn₂SiO₄ luminescent thin film. This is the first report of the investigation and application of ZnO/Si₃N₄ annealed at a high temperature (1000 °C). The fabricated Zn₂SiO₄ film is expected to enable high-frame-rate dynamic observation with ultra-high resolution using our electron beam excitation-assisted optical microscopy.

An Assemblable, Multi-Angle Fluorescence and Ellipsometric Microscope

PubMed Central

Nguyen, Victoria; Rizzo, John

2016-01-01

We introduce a multi-functional microscope for research laboratories that have significant cost and space limitations. The microscope pivots around the sample, operating in upright, inverted, side-on and oblique geometries. At these geometries it is able to perform bright-field, fluorescence and qualitative ellipsometric imaging. It is the first single instrument in the literature to be able to perform all of these functionalities. The system can be assembled by two undergraduate students from a provided manual in less than a day, from off-the-shelf and 3D printed components, which together cost approximately $16k at 2016 market prices. We include a highly specified assembly manual, a summary of design methodologies, and all associated 3D-printing files in hopes that the utility of the design outlives the current component market. This open design approach prepares readers to customize the instrument to specific needs and applications. We also discuss how to select household LEDs as low-cost light sources for fluorescence microscopy. We demonstrate the utility of the microscope in varied geometries and functionalities, with particular emphasis on studying hydrated, solid-supported lipid films and wet biological samples. PMID:27907008

Multispectral digital lensless holographic microscopy: from femtosecond laser to white light LED

NASA Astrophysics Data System (ADS)

Garcia-Sucerquia, J.

2015-04-01

The use of femtosecond laser radiation and super bright white LED in digital lensless holographic microscopy is presented. For the ultrafast laser radiation two different configurations of operation of the microscope are presented and the dissimilar performance of each one analyzed. The microscope operating with a super bright white light LED in combination with optical filters shows very competitive performance as it is compared with more expensive optical sources. The broadband emission of both radiation sources allows the multispectral imaging of biological samples to obtain spectral responses and/or full color images of the microscopic specimens; sections of the head of a Drosophila melanogaster fly are imaged in this contribution. The simple, solid, compact, lightweight, and reliable architecture of digital lensless holographic microscopy operating with broadband light sources to image biological specimens exhibiting micrometer-sized details is evaluated in the present contribution.

High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

PubMed

Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

2016-02-01

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams.

Live cell imaging of cytoskeletal and organelle dynamics in gravity-sensing cells in plant gravitropism.

PubMed

Nakamura, Moritaka; Toyota, Masatsugu; Tasaka, Masao; Morita, Miyo Terao

2015-01-01

Plants sense gravity and change their morphology/growth direction accordingly (gravitropism). The early process of gravitropism, gravity sensing, is supposed to be triggered by sedimentation of starch-filled plastids (amyloplasts) in statocytes such as root columella cells and shoot endodermal cells. For several decades, many scientists have focused on characterizing the role of the amyloplasts and observed their intracellular sedimentation in various plants. Recently, it has been discovered that the complex sedimentary movements of the amyloplasts are created not only by gravity but also by cytoskeletal/organelle dynamics, such as those of actin filaments and the vacuolar membrane. Thus, to understand how plants sense gravity, we need to analyze both amyloplast movements and their regulatory systems in statocytes. We have developed a vertical-stage confocal microscope that allows multicolor fluorescence imaging of amyloplasts, actin filaments and vacuolar membranes in vertically oriented plant tissues. We also developed a centrifuge microscope that allows bright-field imaging of amyloplasts during centrifugation. These microscope systems provide new insights into gravity-sensing mechanisms in Arabidopsis.

Color digital lensless holographic microscopy: laser versus LED illumination.

PubMed

Garcia-Sucerquia, Jorge

2016-08-20

A comparison of the performance of color digital lensless holographic microscopy (CDLHM) as utilized for illumination of RGB lasers or a super-bright white-light LED with a set of spectral filters is presented. As the use of lasers in CDLHM conceals the possibility of having a compact, lightweight, portable, and low cost microscope, and additionally the limited available laser radiation wavelengths limit a real multispectral imaging microscope, here we present the use of super-bright white-light LED and spectral filters for illuminating the sample. The performance of RGB laser-CDLHM and LED-CDLHM is evaluated on imaging a section of the head of a Drosophila melanogaster fly. This comparison shows that there is trade-off between the spatial resolution of the microscope and the light sources utilized, which can be understood with regard to the coherence properties of the illuminating light. Despite the smaller spatial coherence features of LED-CDLHM in comparison with laser-CDLHM, the former shows promise as a portable RGB digital lensless holographic microscope that could be extended to other wavelengths by the use of different spectral filters.

Histologic anatomy of the lesser metatarsophalangeal joint plantar plate.

PubMed

Gregg, J; Marks, P; Silberstein, M; Schneider, T; Kerr, J

2007-03-01

The plantar plate is the fibrocartilaginous structure that supports the ball of the foot, withstanding considerable compressive and tensile forces. This study describes the morphology of the plantar plate in order to understand its function and the pathologic disorders associated with it. Eight lesser metatarsophalangeal joint plantar plates from three soft-embalmed cadavers (74-92 years, two males, one female), and eight lesser metatarsophalangeal joint plantar plates from a fresh cadaver (19-year-old male) were obtained for histology assessment. Paraffin sections (10 microm) in the longitudinal and transverse planes were analyzed with bright-field and polarized light microscopy. The central plantar plate collagen bundles run in the longitudinal plane with varying degrees of undulation. The plantar plate borders run transversely and merge with collateral ligaments and the deep transverse intermetatarsal ligament. Bright-field microscopic evaluation shows the plantar aspect of the plantar plate becomes ligament-like the further distally it tapers, containing fewer chondrocytes, and a greater abundance of fibroblasts. The enthesis reveals longitudinal and interwoven collagen bundles entering the proximal phalanx with multiple interdigitations. Longer interdigitations centrally compared to the dorsal and plantar aspects suggest that the central fibers experience the greatest loads.

Macular photostress and visual experience between microscope and intracameral illumination during cataract surgery.

PubMed

Seo, Hyejin; Nam, Dong Heun; Lee, Jong Yeon; Park, Su Jin; Kim, Yu Jeong; Kim, Seong-Woo; Chung, Tae-Young; Inoue, Makoto; Kim, Terry

2018-02-01

To evaluate macular photostress and visual experience between coaxial microscope illumination versus oblique intracameral illumination during cataract surgery. Gachon University Gil Hospital, Incheon, South Korea. Prospective case series. Consecutive patients who had cataract surgery using microscope illumination and intracameral illumination were included. The patients were asked to complete a questionnaire (seeing strong lights, feeling photophobia, feeling startled (fright) when seeing lights, seeing any colors, seeing any instruments or surgical procedures, and estimating intraoperative visual function) designed to describe their cataract surgery experience. The images projected on the retina of the model eye (rear view) with artificial opaque fragments in the anterior chamber during simulating cataract surgery were compared between the 2 illumination types. Sixty patients completed the questionnaire. Scores for strong lights, photophobia, fright, and color perception were significantly higher with microscope illumination than with intracameral illumination (all P < .001). More patients preferred the intracameral illumination (45 [75.0%]) to the microscope illumination (13 [21.7%]). In the rear-view images created in a model eye, only the bright microscope light in the center was seen without any lens image in the microscope illumination. However, in the intracameral illumination, the less bright light from the light pipe in the periphery and the lens fragments were seen more clearly. In a view of the patients' visual experience, oblique intracameral illumination caused less subjective photostress and was preferred over coaxial microscope illumination. Objective findings from the model-eye experiment correlated to the result of visual experience. Copyright © 2018 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Experimental observation of attosecond control over relativistic electron bunches with two-colour fields

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

Yeung, M.; Rykovanov, S.; Bierbach, J.

2016-12-05

Energy coupling during relativistically intense laser–matter interactions is encoded in the attosecond motion of strongly driven electrons at the pre-formed plasma–vacuum boundary. Studying and controlling this motion can reveal details about the microscopic processes that govern a vast array of light–matter interaction phenomena, including those at the forefront of extreme laser–plasma science such as laser-driven ion acceleration, bright attosecond pulse generation and efficient energy coupling for the generation and study of warm dense matter. Here in this paper, we experimentally demonstrate that by precisely adjusting the relative phase of an additional laser beam operating at the second harmonic of themore » driving laser it is possible to control the trajectories of relativistic electron bunches formed during the interaction with a solid target at the attosecond scale. Finally, we observe significant enhancements in the resulting high-harmonic yield, suggesting potential applications for sources of ultra-bright, extreme ultraviolet attosecond radiation to be used in atomic and molecular pump–probe experiments« less

Autofocusing and Polar Body Detection in Automated Cell Manipulation.

PubMed

Wang, Zenan; Feng, Chen; Ang, Wei Tech; Tan, Steven Yih Min; Latt, Win Tun

2017-05-01

Autofocusing and feature detection are two essential processes for performing automated biological cell manipulation tasks. In this paper, we have introduced a technique capable of focusing on a holding pipette and a mammalian cell under a bright-field microscope automatically, and a technique that can detect and track the presence and orientation of the polar body of an oocyte that is rotated at the tip of a micropipette. Both algorithms were evaluated by using mouse oocytes. Experimental results show that both algorithms achieve very high success rates: 100% and 96%. As robust and accurate image processing methods, they can be widely applied to perform various automated biological cell manipulations.

Nonlinear dynamic phase contrast microscopy for microfluidic and microbiological applications

NASA Astrophysics Data System (ADS)

Denz, C.; Holtmann, F.; Woerdemann, M.; Oevermann, M.

2008-08-01

In live sciences, the observation and analysis of moving living cells, molecular motors or motion of micro- and nano-objects is a current field of research. At the same time, microfluidic innovations are needed for biological and medical applications on a micro- and nano-scale. Conventional microscopy techniques are reaching considerable limits with respect to these issues. A promising approach for this challenge is nonlinear dynamic phase contrast microscopy. It is an alternative full field approach that allows to detect motion as well as phase changes of living unstained micro-objects in real-time, thereby being marker free, without contact and non destructive, i.e. fully biocompatible. The generality of this system allows it to be combined with several other microscope techniques such as conventional bright field or fluorescence microscopy. In this article we will present the dynamic phase contrast technique and its applications in analysis of micro organismic dynamics, micro flow velocimetry and micro-mixing analysis.

Reconstruction of explicit structural properties at the nanoscale via spectroscopic microscopy

NASA Astrophysics Data System (ADS)

Cherkezyan, Lusik; Zhang, Di; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

2016-02-01

The spectrum registered by a reflected-light bright-field spectroscopic microscope (SM) can quantify the microscopically indiscernible, deeply subdiffractional length scales within samples such as biological cells and tissues. Nevertheless, quantification of biological specimens via any optical measures most often reveals ambiguous information about the specific structural properties within the studied samples. Thus, optical quantification remains nonintuitive to users from the diverse fields of technique application. In this work, we demonstrate that the SM signal can be analyzed to reconstruct explicit physical measures of internal structure within label-free, weakly scattering samples: characteristic length scale and the amplitude of spatial refractive-index (RI) fluctuations. We present and validate the reconstruction algorithm via finite-difference time-domain solutions of Maxwell's equations on an example of exponential spatial correlation of RI. We apply the validated algorithm to experimentally measure structural properties within isolated cells from two genetic variants of HT29 colon cancer cell line as well as within a prostate tissue biopsy section. The presented methodology can lead to the development of novel biophotonics techniques that create two-dimensional maps of explicit structural properties within biomaterials: the characteristic size of macromolecular complexes and the variance of local mass density.

Boundary-artifact-free phase retrieval with the transport of intensity equation II: applications to microlens characterization.

PubMed

Zuo, Chao; Chen, Qian; Li, Hongru; Qu, Weijuan; Asundi, Anand

2014-07-28

Boundary conditions play a crucial role in the solution of the transport of intensity equation (TIE). If not appropriately handled, they can create significant boundary artifacts across the reconstruction result. In a previous paper [Opt. Express 22, 9220 (2014)], we presented a new boundary-artifact-free TIE phase retrieval method with use of discrete cosine transform (DCT). Here we report its experimental investigations with applications to the micro-optics characterization. The experimental setup is based on a tunable lens based 4f system attached to a non-modified inverted bright-field microscope. We establish inhomogeneous Neumann boundary values by placing a rectangular aperture in the intermediate image plane of the microscope. Then the boundary values are applied to solve the TIE with our DCT-based TIE solver. Experimental results on microlenses highlight the importance of boundary conditions that often overlooked in simplified models, and confirm that our approach effectively avoid the boundary error even when objects are located at the image borders. It is further demonstrated that our technique is non-interferometric, accurate, fast, full-field, and flexible, rendering it a promising metrological tool for the micro-optics inspection.

Design of a 300-kV gas environmental transmission electron microscope equipped with a cold field emission gun.

PubMed

Isakozawa, Shigeto; Nagaoki, Isao; Watabe, Akira; Nagakubo, Yasuhira; Saito, Nobuhiro; Matsumoto, Hiroaki; Zhang, Xiao Feng; Taniguchi, Yoshifumi; Baba, Norio

2016-08-01

A new in situ environmental transmission electron microscope (ETEM) was developed based on a 300 kV TEM with a cold field emission gun (CFEG). Particular caution was taken in the ETEM design to assure uncompromised imaging and analytical performance of the TEM. Because of the improved pumping system between the gun and column, the vacuum of CFEG was largely improved and the probe current was sufficiently stabilized to operate without tip flashing for 2-3 h or longer. A high brightness of 2.5 × 10(9) A/cm(2) sr was measured at 300 kV, verifying the high quality of the CFEG electron beam. A specially designed gas injection-heating holder was used in the in situ TEM study at elevated temperatures with or without gas around the TEM specimen. Using this holder in a 10 Pa gas atmosphere and specimen temperatures up to 1000°C, high-resolution ETEM performance and analysis were achieved. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

β-relaxation related bright bands in thin film metallic glasses: Localized percolation of flow units captured via transmission electron microscope

NASA Astrophysics Data System (ADS)

Chen, Z. Q.; Huang, P.; Xu, K. W.; Wang, F.; Lu, T. J.

2016-12-01

We report that β-relaxation of amorphous NiW alloy film was effectively enhanced by adding two thin crystalline layers into the amorphous layer. Correspondingly, more bright bands, i.e., nano shear bands, were captured in the amorphous layer, which experienced more pronounced β-relaxations. Based on the potential energy landscape theory, the bright band was proposed to be the localized percolation of flow units corresponding to β-relaxation. Our findings may help connecting experimentally β-relaxation with flow units and shed light on the microstructure origin of β-relaxation.

Microscopy illumination engineering using a low-cost liquid crystal display.

PubMed

Guo, Kaikai; Bian, Zichao; Dong, Siyuan; Nanda, Pariksheet; Wang, Ying Min; Zheng, Guoan

2015-02-01

Illumination engineering is critical for obtaining high-resolution, high-quality images in microscope settings. In a typical microscope, the condenser lens provides sample illumination that is uniform and free from glare. The associated condenser diaphragm can be manually adjusted to obtain the optimal illumination numerical aperture. In this paper, we report a programmable condenser lens for active illumination control. In our prototype setup, we used a $15 liquid crystal display as a transparent spatial light modulator and placed it at the back focal plane of the condenser lens. By setting different binary patterns on the display, we can actively control the illumination and the spatial coherence of the microscope platform. We demonstrated the use of such a simple scheme for multimodal imaging, including bright-field microscopy, darkfield microscopy, phase-contrast microscopy, polarization microscopy, 3D tomographic imaging, and super-resolution Fourier ptychographic imaging. The reported illumination engineering scheme is cost-effective and compatible with most existing platforms. It enables a turnkey solution with high flexibility for researchers in various communities. From the engineering point-of-view, the reported illumination scheme may also provide new insights for the development of multimodal microscopy and Fourier ptychographic imaging.

Study of factors affecting the appearance of colors under microscopes

NASA Astrophysics Data System (ADS)

Zakizadeh, Roshanak; Martinez-Garcia, Juan; Raja, Kiran B.; Siakidis, Christos

2013-11-01

The variation of colors in microscopy systems can be quite critical for some users. To address this problem, a study is conducted to analyze how different factors such as size of the sample, intensity of the microscope's light source and the characteristics of the material like chroma and saturation can affect the color appearance through the eyepiece of the microscope. To study the changes in colors considering these factors, the spectral reflectance of 24 colors of GretagMacbeth Classic ColorChecker® and Mini ColorChecker® which are placed under a Nikon ECLIPSE MA200 microscope®2 using dark filed and bright field illuminations which result in different intensity levels, is measured using a spectroradiometer®3 which was placed in front of the eyepiece of the microscope. The results are compared with the original data from N. Ohta1. The evaluation is done by observing the shift in colors in the CIE 1931 Chromaticity Diagram and the CIELAB space, also by applying a wide set of color-difference formulas, namely: CIELAB, CMC, BFD, CIE94, CIEDE2000, DIN99d and DIN99b. Furthermore, to emphasize on the color regions in which the highest difference is observed, the authors have obtained the results from another microscope; Olympus SZX10®4, which in this case the measurement is done by mounting the spectroradiometer to the camera port of the microscope. The experiment leads to some interesting results, among which is the consistency in the highest difference observed considering different factors or how the change in saturation of the samples of the same hue can affect the results.

Xenon gas field ion source from a single-atom tip

NASA Astrophysics Data System (ADS)

Lai, Wei-Chiao; Lin, Chun-Yueh; Chang, Wei-Tse; Li, Po-Chang; Fu, Tsu-Yi; Chang, Chia-Seng; Tsong, T. T.; Hwang, Ing-Shouh

2017-06-01

Focused ion beam (FIB) systems have become powerful diagnostic and modification tools for nanoscience and nanotechnology. Gas field ion sources (GFISs) built from atomic-size emitters offer the highest brightness among all ion sources and thus can improve the spatial resolution of FIB systems. Here we show that the Ir/W(111) single-atom tip (SAT) can emit high-brightness Xe+ ion beams with a high current stability. The ion emission current versus extraction voltage was analyzed from 150 K up to 309 K. The optimal emitter temperature for maximum Xe+ ion emission was ˜150 K and the reduced brightness at the Xe gas pressure of 1 × 10-4 torr is two to three orders of magnitude higher than that of a Ga liquid metal ion source, and four to five orders of magnitude higher than that of a Xe inductively coupled plasma ion source. Most surprisingly, the SAT emitter remained stable even when operated at 309 K. Even though the ion current decreased with increasing temperature, the current at room temperature (RT) could still reach over 1 pA when the gas pressure was higher than 1 × 10-3 torr, indicating the feasibility of RT-Xe-GFIS for application to FIB systems. The operation temperature of Xe-SAT-GFIS is considerably higher than the cryogenic temperature required for the helium ion microscope (HIM), which offers great technical advantages because only simple or no cooling schemes can be adopted. Thus, Xe-GFIS-FIB would be easy to implement and may become a powerful tool for nanoscale milling and secondary ion mass spectroscopy.

Wavefront image sensor chip

PubMed Central

Cui, Xiquan; Ren, Jian; Tearney, Guillermo J.; Yang, Changhuei

2010-01-01

We report the implementation of an image sensor chip, termed wavefront image sensor chip (WIS), that can measure both intensity/amplitude and phase front variations of a light wave separately and quantitatively. By monitoring the tightly confined transmitted light spots through a circular aperture grid in a high Fresnel number regime, we can measure both intensity and phase front variations with a high sampling density (11 µm) and high sensitivity (the sensitivity of normalized phase gradient measurement is 0.1 mrad under the typical working condition). By using WIS in a standard microscope, we can collect both bright-field (transmitted light intensity) and normalized phase gradient images. Our experiments further demonstrate that the normalized phase gradient images of polystyrene microspheres, unstained and stained starfish embryos, and strongly birefringent potato starch granules are improved versions of their corresponding differential interference contrast (DIC) microscope images in that they are artifact-free and quantitative. Besides phase microscopy, WIS can benefit machine recognition, object ranging, and texture assessment for a variety of applications. PMID:20721059

Defect-mediated phonon dynamics in TaS2 and WSe2

PubMed Central

Cremons, Daniel R.; Plemmons, Dayne A.; Flannigan, David J.

2017-01-01

We report correlative crystallographic and morphological studies of defect-dependent phonon dynamics in single flakes of 1T-TaS2 and 2H-WSe2 using selected-area diffraction and bright-field imaging in an ultrafast electron microscope. In both materials, we observe in-plane speed-of-sound acoustic-phonon wave trains, the dynamics of which (i.e., emergence, propagation, and interference) are strongly dependent upon discrete interfacial features (e.g., vacuum/crystal and crystal/crystal interfaces). In TaS2, we observe cross-propagating in-plane acoustic-phonon wave trains of differing frequencies that undergo coherent interference approximately 200 ps after initial emergence from distinct interfacial regions. With ultrafast bright-field imaging, the properties of the interfering wave trains are observed to correspond to the beat frequency of the individual oscillations, while intensity oscillations of Bragg spots generated from selected areas within the region of interest match well with the real-space dynamics. In WSe2, distinct acoustic-phonon dynamics are observed emanating and propagating away from structurally dissimilar morphological discontinuities (vacuum/crystal interface and crystal terrace), and results of ultrafast selected-area diffraction reveal thickness-dependent phonon frequencies. The overall observed dynamics are well-described using finite element analysis and time-dependent linear-elastic continuum mechanics. PMID:28503630

Visualization of multipolar longitudinal and transversal surface plasmon modes in nanowire dimers.

PubMed

Alber, Ina; Sigle, Wilfried; Müller, Sven; Neumann, Reinhard; Picht, Oliver; Rauber, Markus; van Aken, Peter A; Toimil-Molares, Maria Eugenia

2011-12-27

We study the transversal and longitudinal localized surface plasmon resonances in single nanowires and nanowire dimers excited by the fast traveling electron beam in a transmission electron microscope equipped with high-resolution electron energy-loss spectroscopy. Bright and dark longitudinal modes up to the fifth order are resolved on individual metallic nanowires. On nanowire dimers, mode splitting into bonding and antibonding is measured up to the third order for several dimers with various aspect ratio and controlled gap size. We observe that the electric field maxima of the bonding modes are shifted toward the gap, while the electric field maxima of the antibonding modes are shifted toward the dimer ends. Finally, we observe that the transversal mode is not detected in the region of the dimer gap and decays away from the rod more rapidly than the longitudinal modes.

How to track protists in three dimensions

NASA Astrophysics Data System (ADS)

Drescher, Knut; Leptos, Kyriacos C.; Goldstein, Raymond E.

2009-01-01

We present an apparatus optimized for tracking swimming micro-organisms in the size range of 10-1000 μm, in three dimensions (3Ds), far from surfaces, and with negligible background convective fluid motion. Charge coupled device cameras attached to two long working distance microscopes synchronously image the sample from two perpendicular directions, with narrow band dark-field or bright-field illumination chosen to avoid triggering a phototactic response. The images from the two cameras can be combined to yield 3D tracks of the organism. Using additional, highly directional broad-spectrum illumination with millisecond timing control the phototactic trajectories in 3D of organisms ranging from Chlamydomonas to Volvox can be studied in detail. Surface-mediated hydrodynamic interactions can also be investigated without convective interference. Minimal modifications to the apparatus allow for studies of chemotaxis and other taxes.

Cryo X-ray microscope with flat sample geometry for correlative fluorescence and nanoscale tomographic imaging.

PubMed

Schneider, Gerd; Guttmann, Peter; Rehbein, Stefan; Werner, Stephan; Follath, Rolf

2012-02-01

X-ray imaging offers a new 3-D view into cells. With its ability to penetrate whole hydrated cells it is ideally suited for pairing fluorescence light microscopy and nanoscale X-ray tomography. In this paper, we describe the X-ray optical set-up and the design of the cryo full-field transmission X-ray microscope (TXM) at the electron storage ring BESSY II. Compared to previous TXM set-ups with zone plate condenser monochromator, the new X-ray optical layout employs an undulator source, a spherical grating monochromator and an elliptically shaped glass capillary mirror as condenser. This set-up improves the spectral resolution by an order of magnitude. Furthermore, the partially coherent object illumination improves the contrast transfer of the microscope compared to incoherent conditions. With the new TXM, cells grown on flat support grids can be tilted perpendicular to the optical axis without any geometrical restrictions by the previously required pinhole for the zone plate monochromator close to the sample plane. We also developed an incorporated fluorescence light microscope which permits to record fluorescence, bright field and DIC images of cryogenic cells inside the TXM. For TXM tomography, imaging with multi-keV X-rays is a straightforward approach to increase the depth of focus. Under these conditions phase contrast imaging is necessary. For soft X-rays with shrinking depth of focus towards 10nm spatial resolution, thin optical sections through a thick specimen might be obtained by deconvolution X-ray microscopy. As alternative 3-D X-ray imaging techniques, the confocal cryo-STXM and the dual beam cryo-FIB/STXM with photoelectron detection are proposed. Copyright © 2012 Elsevier Inc. All rights reserved.

The influence of the microscope lamp filament colour temperature on the process of digital images of histological slides acquisition standardization.

PubMed

Korzynska, Anna; Roszkowiak, Lukasz; Pijanowska, Dorota; Kozlowski, Wojciech; Markiewicz, Tomasz

2014-01-01

The aim of this study is to compare the digital images of the tissue biopsy captured with optical microscope using bright field technique under various light conditions. The range of colour's variation in immunohistochemically stained with 3,3'-Diaminobenzidine and Haematoxylin tissue samples is immense and coming from various sources. One of them is inadequate setting of camera's white balance to microscope's light colour temperature. Although this type of error can be easily handled during the stage of image acquisition, it can be eliminated with use of colour adjustment algorithms. The examination of the dependence of colour variation from microscope's light temperature and settings of the camera is done as an introductory research to the process of automatic colour standardization. Six fields of view with empty space among the tissue samples have been selected for analysis. Each field of view has been acquired 225 times with various microscope light temperature and camera white balance settings. The fourteen randomly chosen images have been corrected and compared, with the reference image, by the following methods: Mean Square Error, Structural SIMilarity and visual assessment of viewer. For two types of backgrounds and two types of objects, the statistical image descriptors: range, median, mean and its standard deviation of chromaticity on a and b channels from CIELab colour space, and luminance L, and local colour variability for objects' specific area have been calculated. The results have been averaged for 6 images acquired in the same light conditions and camera settings for each sample. The analysis of the results leads to the following conclusions: (1) the images collected with white balance setting adjusted to light colour temperature clusters in certain area of chromatic space, (2) the process of white balance correction for images collected with white balance camera settings not matched to the light temperature moves image descriptors into proper chromatic space but simultaneously the value of luminance changes. So the process of the image unification in a sense of colour fidelity can be solved in separate introductory stage before the automatic image analysis.

A spectral k-means approach to bright-field cell image segmentation.

PubMed

Bradbury, Laura; Wan, Justin W L

2010-01-01

Automatic segmentation of bright-field cell images is important to cell biologists, but difficult to complete due to the complex nature of the cells in bright-field images (poor contrast, broken halo, missing boundaries). Standard approaches such as level set segmentation and active contours work well for fluorescent images where cells appear as round shape, but become less effective when optical artifacts such as halo exist in bright-field images. In this paper, we present a robust segmentation method which combines the spectral and k-means clustering techniques to locate cells in bright-field images. This approach models an image as a matrix graph and segment different regions of the image by computing the appropriate eigenvectors of the matrix graph and using the k-means algorithm. We illustrate the effectiveness of the method by segmentation results of C2C12 (muscle) cells in bright-field images.

Bright-field electron tomography of individual inorganic fullerene-like structures

NASA Astrophysics Data System (ADS)

Bar Sadan, Maya; Wolf, Sharon G.; Houben, Lothar

2010-03-01

Nanotubes and fullerene-like nanoparticles of various inorganic layered compounds have been studied extensively in recent years. Their characterisation on the atomic scale has proven essential for progress in synthesis as well as for the theoretical modelling of their physical properties. We show that with electron tomography it is possible to achieve a reliable reconstruction of the 3D structure of nested WS2 or MoS2 fullerene-like and nanotube structures with sub-nanometre resolution using electron microscopes that are not aberration-corrected. Model-based simulations were used to identify imaging parameters, under which structural features such as the shell structure can be retained in the tomogram reconstructed from bright-field micrographs. The isolation of a particle out of an agglomerate for the analysis of a single structure and its interconnection with other particles is facilitated through the tomograms. The internal structure of the layers within the particle alongside the shape and content of its internal void are reconstructed. The tomographic reconstruction yields insights regarding the growth process as well as structural defects, such as non-continuous layers, which relate to the lubrication properties.Nanotubes and fullerene-like nanoparticles of various inorganic layered compounds have been studied extensively in recent years. Their characterisation on the atomic scale has proven essential for progress in synthesis as well as for the theoretical modelling of their physical properties. We show that with electron tomography it is possible to achieve a reliable reconstruction of the 3D structure of nested WS2 or MoS2 fullerene-like and nanotube structures with sub-nanometre resolution using electron microscopes that are not aberration-corrected. Model-based simulations were used to identify imaging parameters, under which structural features such as the shell structure can be retained in the tomogram reconstructed from bright-field micrographs. The isolation of a particle out of an agglomerate for the analysis of a single structure and its interconnection with other particles is facilitated through the tomograms. The internal structure of the layers within the particle alongside the shape and content of its internal void are reconstructed. The tomographic reconstruction yields insights regarding the growth process as well as structural defects, such as non-continuous layers, which relate to the lubrication properties. Electronic supplementary information (ESI) available: Figs. S1 and S2 and movies S1-S6. See DOI: 10.1039/b9nr00251k

Extraction of the number of peroxisomes in yeast cells by automated image analysis.

PubMed

Niemistö, Antti; Selinummi, Jyrki; Saleem, Ramsey; Shmulevich, Ilya; Aitchison, John; Yli-Harja, Olli

2006-01-01

An automated image analysis method for extracting the number of peroxisomes in yeast cells is presented. Two images of the cell population are required for the method: a bright field microscope image from which the yeast cells are detected and the respective fluorescent image from which the number of peroxisomes in each cell is found. The segmentation of the cells is based on clustering the local mean-variance space. The watershed transformation is thereafter employed to separate cells that are clustered together. The peroxisomes are detected by thresholding the fluorescent image. The method is tested with several images of a budding yeast Saccharomyces cerevisiae population, and the results are compared with manually obtained results.

Quantitative phase microscopy for cellular dynamics based on transport of intensity equation.

PubMed

Li, Ying; Di, Jianglei; Ma, Chaojie; Zhang, Jiwei; Zhong, Jinzhan; Wang, Kaiqiang; Xi, Teli; Zhao, Jianlin

2018-01-08

We demonstrate a simple method for quantitative phase imaging of tiny transparent objects such as living cells based on the transport of intensity equation. The experiments are performed using an inverted bright field microscope upgraded with a flipping imaging module, which enables to simultaneously create two laterally separated images with unequal defocus distances. This add-on module does not include any lenses or gratings and is cost-effective and easy-to-alignment. The validity of this method is confirmed by the measurement of microlens array and human osteoblastic cells in culture, indicating its potential in the applications of dynamically measuring living cells and other transparent specimens in a quantitative, non-invasive and label-free manner.

Dark-Bright Soliton Dynamics Beyond the Mean-Field Approximation

NASA Astrophysics Data System (ADS)

Katsimiga, Garyfallia; Koutentakis, Georgios; Mistakidis, Simeon; Kevrekidis, Panagiotis; Schmelcher, Peter; Theory Group of Fundamental Processes in Quantum Physics Team

2017-04-01

The dynamics of dark bright solitons beyond the mean-field approximation is investigated. We first examine the case of a single dark-bright soliton and its oscillations within a parabolic trap. Subsequently, we move to the setting of collisions, comparing the mean-field approximation to that involving multiple orbitals in both the dark and the bright component. Fragmentation is present and significantly affects the dynamics, especially in the case of slower solitons and in that of lower atom numbers. It is shown that the presence of fragmentation allows for bipartite entanglement between the distinguishable species. Most importantly the interplay between fragmentation and entanglement leads to the decay of each of the initial mean-field dark-bright solitons into fast and slow fragmented dark-bright structures. A variety of excitations including dark-bright solitons in multiple (concurrently populated) orbitals is observed. Dark-antidark states and domain-wall-bright soliton complexes can also be observed to arise spontaneously in the beyond mean-field dynamics. Deutsche Forschungsgemeinschaft (DFG) in the framework of the SFB 925 ``Light induced dynamics and control of correlated quantum systems''.

Resonance Raman microscopy in combination with partial dark-field microscopy lights up a new path in malaria diagnostics.

PubMed

Wood, Bayden R; Hermelink, Antje; Lasch, Peter; Bambery, Keith R; Webster, Grant T; Khiavi, Mehdi Asghari; Cooke, Brian M; Deed, Samantha; Naumann, Dieter; McNaughton, Don

2009-06-01

Our goal is to produce a rapid and accurate diagnostic tool for malaria using resonance Raman spectroscopy to detect small inclusions of haemozoin in Plasmodium falciparum infected red blood cells. In pursuit of this aim we serendipitously discovered a partial dark-field effect generated by our experimental setup, which helps identify in thick blood films potential parasites that are normally difficult to see with conventional bright-field microscopy. The haemozoin deposits 'light up' and these can be selectively targeted with the Raman microscope to confirm the presence or absence of haemozoin by the strong 1569 cm(-1) band, which is a marker for haemozoin. With newly developed imaging Raman microscopes incorporating ultra-sensitive rapid readout CCDs it is possible to obtain spectra with a good signal-to-noise ratio in 1 second. Moreover, images from a smear of potentially infected cells can be recorded and analysed with multivariate methods. The reconstructed images show what appear to be sub-micron-inclusions of haemozoin in some cells indicating that the technique has potential to identify low pigmented forms of the parasite including early trophozoite-stage infected cells. Further work is required to unambiguously confirm the presence of such forms through systematic staining but the results are indeed promising and may lead to the development of a new Raman-based malaria diagnostic.

EDITORIAL: Nature's building blocks Nature's building blocks

NASA Astrophysics Data System (ADS)

Engel, Andreas

2009-10-01

The scanning tunnelling microscope (STM), invented by Gerd Binnig and Heinrich Rohrer in the early 1980s in the IBM Laboratory in Zurich, and the atomic force microscope (AFM) that followed shortly afterwards, were key developments that initiated a new era in scientific research: nanotechnology. These and related scanning probe microscopes have become fruitful tools in the study of cells, supramolecular assemblies and single biomolecules, as well as other nanoscale structures. In particular, the ability to investigate living matter in native environments made possible by atomic force microscopy, has allowed pronounced progress in biological research. The journal Nanotechnology was the first to serve as a publication platform for this rapidly developing field of science. The journal celebrates its 20th volume with this special issue, which presents a collection of original research articles in various fields of science, but all with the common feature that the structures, processes and functions all take place at the nanometre scale. Scanning probe microscopes are constantly being devised with increasingly sophisticated sensing and actuating features that optimize their performance. However, while these tools continue to provide impressive and informative images of nanoscale systems and allow single molecules to be manipulated with increasing dexterity, a wider field of research activity stimulated either by or for biology has emerged. The unique properties of matter at the nanoscale, such as localized surface plasmons supported by nanostructures, have been exploited in sensors with unprecedented sensitivity. Nanostructures have also found a profitable role in the encapsulation of molecules for 'smart' drug delivery. The potential application of DNA in the self-assembly of nanostructures guided by molecular recognition is another rapidly advancing area of research. In this issue a group of researchers in Germany report how the addition of copper ions can promote the stability of modified double-stranded DNA. They use scanning force microscope observations to provide insights into the energy landscape as DNA complexes form. This research provides just one example of how developments on biological systems are being applied to research across the spectrum of disciplines. This 20th volume special issue provides a snapshot of current state-of-the-art research activity in various areas of nanotechnology, and highlights the breadth and range of research progressing in this field. The developments reported here highlight the continued prominence of biology-related research and promise a bright future for nanotechnology.

Automatic segementation of histological structures in normal and neoplastic mammary gland tissue sections

NASA Astrophysics Data System (ADS)

Fernandez-Gonzalez, Rodrigo; Deschamps, Thomas; Idica, Adam; Malladi, Ravikanth; Ortiz de Solorzano, Carlos

2003-07-01

In this paper we present a scheme for real time segmentation of histological structures in microscopic images of normal and neoplastic mammary gland sections. Paraffin embedded or frozen tissue blocks are sliced, and sections are stained with hematoxylin and eosin (H&E). The sections are then imaged using conventional bright field microscopy. The background of the images is corrected by arithmetic manipulation using a "phantom." Then we use the fast marching method with a speed function that depends on the brightness gradient of the image to obtain a preliminary approximation to the boundaries of the structures of interest within a region of interest (ROI) of the entire section manually selected by the user. We use the result of the fast marching method as the initial condition for the level set motion equation. We run this last method for a few steps and obtain the final result of the segmentation. These results can be connected from section to section to build a three-dimensional reconstruction of the entire tissue block that we are studying.

High brightness, low coherence, digital holographic microscopy for 3D visualization of an in-vitro sandwiched biological sample.

PubMed

Abdelsalam, D G; Yasui, Takeshi

2017-05-01

We achieve practically a bright-field digital holographic microscopy (DHM) configuration free from coherent noise for three-dimensional (3D) visualization of an in-vitro sandwiched sarcomere sample. Visualization of such sandwiched samples by conventional atomic force microscope (AFM) is impossible, while visualization using DHM with long coherent lengths is challenging. The proposed configuration is comprised of an ultrashort pulse laser source and a Mach-Zehnder interferometer in transmission. Periodically poled lithium niobate (PPLN) crystal was used to convert the fundamental beam by second harmonic generation (SHG) to the generated beam fit to the CCD camera used. The experimental results show that the contrast of the reconstructed phase image is improved to a higher degree compared to a He-Ne laser based result. We attribute this improvement to two things: the feature of the femtosecond pulse light, which acts as a chopper for coherent noise suppression, and the fact that the variance of a coherent mode can be reduced by a factor of 9 due to low loss through a nonlinear medium.

Hybrid nanocomposite coatings from metal (Mg alloy)-drug deposited onto medical implant by laser adaptive ablation deposition technique

NASA Astrophysics Data System (ADS)

Serbezov, Valery; Sotirov, Sotir; Serbezov, Svetlin

2013-03-01

Drug-eluting medical implants are active implants whose function is to create healing effects. The current requirements for active medical coatings for Drug-eluting medical implants are to be biocompatible, biodegradable, polymer free, mechanically stable and enable a controlled release of one or more drugs and defined degradation. This brings hybrid nanocomposite coatings into focus especially in the field of cardiovascular implants. We studied the properties of Metal (Mg alloy)-Paclitaxel coatings obtained by novel Laser Adaptive Ablation Deposition Technique (LAAD) onto cardiovascular stents from 316 LVM stainless steel material. The morphology and topology of coatings were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Comparative measurements were made of the morphology and topology of hybrid, polymer free nanocomposite coatings deposited by LAAD and polymerdrug coatings deposited by classical spray technique. The coatings obtained by LAAD are homogeneous without damages and cracks. Metal nanoparticles with sizes from 40 nm to 230 nm were obtained in drug matrixes. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of metal nanoparticles presence in hybrid nanocomposites coatings. The new technology opens up possibilities to obtain new hybrid nanocomposite coatings with applications in medicine, pharmacy and biochemistry.

Chip-on-the-tip ultra-compact flexible endoscopic epifluorescence video-microscope for in-vivo imaging in medical and biomedical fields

NASA Astrophysics Data System (ADS)

Matz, Gregor; Messerschmidt, Bernhard; Göbel, Werner; Filser, Severin; Betz, Christian; Kunze, Marcel; Flaemig, Sven; Ehrhardt, André; Irion, Klaus-Martin; Herms, Jochen; Gross, Herbert

2017-02-01

We demonstrate a flexible stand-alone, minimally invasive video-endomicroscope with an outer diameter of 1.6 mm and a length of the rigid tip of 6.7 mm that enables surgeons and biologists to image hardly accessible regions in-vivo in epifluorescence mode. The 60 mg light device improves state-of-the-art objectives by a double deflection approach using a side-fire fiber in combination with spherical microlenses, GRIN-lenses with a specific adapted gradient index profile and an extremely miniaturized chip-on-the-tip camera to achieve an excellent imaging quality. A high NA of 0.7 enables the observation of subcellular features within the entire field of view with a diameter of 183 μm, assure a bright and high-contrast image and promise a good overview during the intervention. Ex-vivo measurements of biological samples confirmed the functionality of the probe.

The Development of Teaching and Learning in Bright-Field Microscopy Technique

ERIC Educational Resources Information Center

Iskandar, Yulita Hanum P.; Mahmud, Nurul Ethika; Wahab, Wan Nor Amilah Wan Abdul; Jamil, Noor Izani Noor; Basir, Nurlida

2013-01-01

E-learning should be pedagogically-driven rather than technologically-driven. The objectives of this study are to develop an interactive learning system in bright-field microscopy technique in order to support students' achievement of their intended learning outcomes. An interactive learning system on bright-field microscopy technique was…

Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides

DOE PAGES

Selig, Malte; Berghäuser, Gunnar; Raja, Archana; ...

2016-11-07

Atomically thin transition metal dichalcogenides are direct-gap semiconductors with strong light–matter and Coulomb interactions. The latter accounts for tightly bound excitons, which dominate their optical properties. Besides the optically accessible bright excitons, these systems exhibit a variety of dark excitonic states. They are not visible in the optical spectra, but can strongly influence the coherence lifetime and the linewidth of the emission from bright exciton states. We investigate the microscopic origin of the excitonic coherence lifetime in two representative materials (WS 2 and MoSe 2) through a study combining microscopic theory with spectroscopic measurements. We also show that the excitonicmore » coherence lifetime is determined by phonon-induced intravalley scattering and intervalley scattering into dark excitonic states. Particularly, we identify exciton relaxation processes involving phonon emission into lower-lying dark states that are operative at all temperatures, in WS 2.« less

Quantitative phase imaging of arthropods

PubMed Central

Sridharan, Shamira; Katz, Aron; Soto-Adames, Felipe; Popescu, Gabriel

2015-01-01

Abstract. Classification of arthropods is performed by characterization of fine features such as setae and cuticles. An unstained whole arthropod specimen mounted on a slide can be preserved for many decades, but is difficult to study since current methods require sample manipulation or tedious image processing. Spatial light interference microscopy (SLIM) is a quantitative phase imaging (QPI) technique that is an add-on module to a commercial phase contrast microscope. We use SLIM to image a whole organism springtail Ceratophysella denticulata mounted on a slide. This is the first time, to our knowledge, that an entire organism has been imaged using QPI. We also demonstrate the ability of SLIM to image fine structures in addition to providing quantitative data that cannot be obtained by traditional bright field microscopy. PMID:26334858

Three-dimensional particle tracking via tunable color-encoded multiplexing.

PubMed

Duocastella, Martí; Theriault, Christian; Arnold, Craig B

2016-03-01

We present a novel 3D tracking approach capable of locating single particles with nanometric precision over wide axial ranges. Our method uses a fast acousto-optic liquid lens implemented in a bright field microscope to multiplex light based on color into different and selectable focal planes. By separating the red, green, and blue channels from an image captured with a color camera, information from up to three focal planes can be retrieved. Multiplane information from the particle diffraction rings enables precisely locating and tracking individual objects up to an axial range about 5 times larger than conventional single-plane approaches. We apply our method to the 3D visualization of the well-known coffee-stain phenomenon in evaporating water droplets.

Moving Toward the Light: Using New Technology to Answer Old Questions

PubMed Central

LUCITTI, JENNIFER L.; DICKINSON, MARY E.

2006-01-01

Fluorescence microscopy has become a principle methodology in the field of developmental biology. Recent technological advances have led to the design of high-speed and high-resolution confocal and multiphoton microscopes that enable researchers to obtain three- and four-dimensional information in living cells and whole embryos. Paralleling this progress, the development of stable and bright vital fluorescent probes has revolutionized the ability to track individual cells in vitro and in vivo and to visualize intercellular and subcellular molecular interactions in real time. Combining imaging modalities and labeling techniques that are increasingly unobtrusive to cell and whole animal function, our understanding of how proteins interact, tissues take form, and organs synchronize to create a functioning animal is reaching a whole new level. PMID:16690954

Optical activity in chiral stacks of 2D semiconductors

NASA Astrophysics Data System (ADS)

Poshakinskiy, Alexander V.; Kazanov, Dmitrii R.; Shubina, Tatiana V.; Tarasenko, Sergey A.

2018-03-01

We show that the stacks of two-dimensional semiconductor crystals with the chiral packing exhibit optical activity and circular dichroism. We develop a microscopic theory of these phenomena in the spectral range of exciton transitions that takes into account the spin-dependent hopping of excitons between the layers in the stack and the interlayer coupling of excitons via electromagnetic field. For the stacks of realistic two-dimensional semiconductors such as transition metal dichalcogenides, we calculate the rotation and ellipticity angles of radiation transmitted through such structures. The angles are resonantly enhanced at the frequencies of both bright and dark exciton modes in the stack. We also study the photoluminescence of chiral stacks and show that it is circularly polarized.

Magnetic topological analysis of coronal bright points

NASA Astrophysics Data System (ADS)

Galsgaard, K.; Madjarska, M. S.; Moreno-Insertis, F.; Huang, Z.; Wiegelmann, T.

2017-10-01

Context. We report on the first of a series of studies on coronal bright points which investigate the physical mechanism that generates these phenomena. Aims: The aim of this paper is to understand the magnetic-field structure that hosts the bright points. Methods: We use longitudinal magnetograms taken by the Solar Optical Telescope with the Narrowband Filter Imager. For a single case, magnetograms from the Helioseismic and Magnetic Imager were added to the analysis. The longitudinal magnetic field component is used to derive the potential magnetic fields of the large regions around the bright points. A magneto-static field extrapolation method is tested to verify the accuracy of the potential field modelling. The three dimensional magnetic fields are investigated for the presence of magnetic null points and their influence on the local magnetic domain. Results: In nine out of ten cases the bright point resides in areas where the coronal magnetic field contains an opposite polarity intrusion defining a magnetic null point above it. We find that X-ray bright points reside, in these nine cases, in a limited part of the projected fan-dome area, either fully inside the dome or expanding over a limited area below which typically a dominant flux concentration resides. The tenth bright point is located in a bipolar loop system without an overlying null point. Conclusions: All bright points in coronal holes and two out of three bright points in quiet Sun regions are seen to reside in regions containing a magnetic null point. An as yet unidentified process(es) generates the brigh points in specific regions of the fan-dome structure. The movies are available at http://www.aanda.org

Far-infrared Beamline at the Canadian Light Source

NASA Astrophysics Data System (ADS)

Zhao, Jianbao; Billinghurst, Brant

2017-06-01

Far-infrared is a particularly useful technique for studies on lattice modes as they generally appear in the Far-infrared region. Far-infrared is also an important tool for gathering information on the electrical transport properties of metallic materials and the band gap of semiconductors. This poster will describe the horizontal microscope that has recently been built in the Far-infrared beamline at the Canadian Light Source Inc. (CLS). This microscope is specially designed for high-pressure Far-infrared absorbance and reflectance spectroscopic studies. The numerical aperture (0.5) and the long working distance (82.1 mm) in the microscope are good fits for Diamond Anvil Cell (DAC). The spectra are recorded using liquid helium cooled Si bolometer or Ge:Cu detector. The pressure in the DAC can be determined by using the fluorescence spectrometer available onsite. The Far-infrared beamline at CLS is a state-of-the-art synchrotron facility, offering significantly more brightness than conventional sources. Because of the high brightness of the synchrotron radiation, we can obtain the Far-infrared reflectance/absorbance spectra on the small samples with more throughput than with a conventional source. The Far-infrared beamline is open to users through peer review.

Electrically stimulated contractions of Vorticella convallaria

NASA Astrophysics Data System (ADS)

Kantha, Deependra; van Winkle, David

2009-03-01

The contraction of Vorticella convallaria was triggered by applying a voltage pulse in its host culturing medium. The 50V, 1ms wide pulse was applied across platinum wires separated by 0.7 cm on a microscope slide. The contractions were recorded as cines (image sequences) by a Phantom V5 camera (Vision Research) on a bright field microscope with 20X objective, with the image size of 256 pixels x 128 pixels at 7352 pictures per second. The starting time of the cines was synchronized with the starting of the electrical pulse. We recorded five contractions of each of 12 organisms. The cines were analyzed to obtain the initiation time, defined as the difference in time between the leading edge of the electrical pulse and the first frame showing zooid movement. From multiple contractions of same organism, we found the initiation time is reproducible. In comparing different organisms, we found the average initiation time of 1.73 ms with a standard deviation of 0.63 ms. This research is supported by the state of Florida (MARTECH) and Research Corporation.

Brightness field distributions of microlens arrays using micro molding.

PubMed

Cheng, Hsin-Chung; Huang, Chiung-Fang; Lin, Yi; Shen, Yung-Kang

2010-12-20

This study describes the brightness field distributions of microlens arrays fabricated by micro injection molding (μIM) and micro injection-compression molding (μICM). The process for fabricating microlens arrays used room-temperature imprint lithography, photoresist reflow, electroforming, μIM, μICM, and optical properties measurement. Analytical results indicate that the brightness field distribution of the molded microlens arrays generated by μICM is better than those made using μIM. Our results further demonstrate that mold temperature is the most important processing parameter for brightness field distribution of molded microlens arrays made by μIM or μICM.

Landcover Based Optimal Deconvolution of PALS L-band Microwave Brightness Temperature

NASA Technical Reports Server (NTRS)

Limaye, Ashutosh S.; Crosson, William L.; Laymon, Charles A.; Njoku, Eni G.

2004-01-01

An optimal de-convolution (ODC) technique has been developed to estimate microwave brightness temperatures of agricultural fields using microwave radiometer observations. The technique is applied to airborne measurements taken by the Passive and Active L and S band (PALS) sensor in Iowa during Soil Moisture Experiments in 2002 (SMEX02). Agricultural fields in the study area were predominantly soybeans and corn. The brightness temperatures of corn and soybeans were observed to be significantly different because of large differences in vegetation biomass. PALS observations have significant over-sampling; observations were made about 100 m apart and the sensor footprint extends to about 400 m. Conventionally, observations of this type are averaged to produce smooth spatial data fields of brightness temperatures. However, the conventional approach is in contrast to reality in which the brightness temperatures are in fact strongly dependent on landcover, which is characterized by sharp boundaries. In this study, we mathematically de-convolve the observations into brightness temperature at the field scale (500-800m) using the sensor antenna response function. The result is more accurate spatial representation of field-scale brightness temperatures, which may in turn lead to more accurate soil moisture retrieval.

Exploring the extremely low surface brightness sky: distances to 23 newly discovered objects in Dragonfly fields

NASA Astrophysics Data System (ADS)

van Dokkum, Pieter

2016-10-01

We are obtaining deep, wide field images of nearby galaxies with the Dragonfly Telephoto Array. This telescope is optimized for low surface brightness imaging, and we are finding many low surface brightness objects in the Dragonfly fields. In Cycle 22 we obtained ACS imaging for 7 galaxies that we had discovered in a Dragonfly image of the galaxy M101. Unexpectedly, the ACS data show that only 3 of the galaxies are members of the M101 group, and the other 4 are very large Ultra Diffuse Galaxies (UDGs) at much greater distance. Building on our Cycle 22 program, here we request ACS imaging for 23 newly discovered low surface brightness objects in four Dragonfly fields centered on the galaxies NGC 1052, NGC 1084, NGC 3384, and NGC 4258. The immediate goals are to construct the satellite luminosity functions in these four fields and to constrain the number density of UDGs that are not in rich clusters. More generally, this complete sample of extremely low surface brightness objects provides the first systematic insight into galaxies whose brightness peaks at >25 mag/arcsec^2.

Cross-sectional transmission electron microscopic study of irradiation induced nano-crystallization of nickel in a W/Ni multilayer.

PubMed

Bagchi, Sharmistha; Lalla, N P

2008-06-11

The present study reports the cross-sectional transmission electron microscopic investigations of swift heavy ion-irradiation induced nano-size recrystallization of Ni in a nearly immiscible W/Ni multilayer structure. Multilayer structures (MLS) of [W(25 Å)/Ni(25 Å)](10BL) were grown on Si-(100) substrate by the ion-beam sputtering technique. The as-synthesized MLS were subjected to 120 MeV-Au(9+) ion-irradiation to a fluence of ∼5 × 10(13) ions cm(-2). Wide-angle x-ray diffraction studies of pristine as well as irradiated W/Ni multilayers show deterioration of the superlattice structure, whereas x-ray reflectivity (XRR) measurement reveals a nearly unaffected microstructure after irradiation. Analysis of the XRR data using 'Parratt's formalism' does show a significant increase of W/Ni interface roughness. Cross-sectional transmission electron microscopy (TEM) studies carried out in diffraction and imaging modes (including bright-field and dark-field imaging), show that at high irradiation dose the intralayer microstructure of Ni becomes nano-crystalline (1-2 nm). During these irradiation induced changes of the intralayer microstructure, the interlayer definition of the W and Ni layers still remains intact. The observed nano-recrystallization of Ni has been attributed to competition between low miscibility of the W/Ni interface and the ion-beam induced mixing kinetics.

Imaging of the 3D dynamics of flagellar beating in human sperm.

PubMed

Silva-Villalobos, F; Pimentel, J A; Darszon, A; Corkidi, G

2014-01-01

The study of the mechanical and environmental factors that regulate a fundamental event such as fertilization have been subject of multiple studies. Nevertheless, the microscopical size of the spermatozoa and the high beating frequency of their flagella (up to 20 Hz) impose a series of technological challenges for the study of the mechanical factors implicated. Traditionally, due to the inherent characteristics of the rapid sperm movement, and to the technological limitations of microscopes (optical or confocal) to follow in three dimensions (3D) their movement, the analysis of their dynamics has been studied in two dimensions, when the head is confined to a surface. Flagella propel sperm and while their head can be confined to a surface, flagellar movement is not restricted to 2D, always displaying 3D components. In this work, we present a highly novel and useful tool to analyze sperm flagella dynamics in 3D. The basis of the method is a 100 Hz oscillating objective mounted on a bright field optical microscope covering a 16 microns depth space at a rate of ~ 5000 images per second. The best flagellum focused subregions were associated to their respective Z real 3D position. Unprecedented graphical results making evident the 3D movement of the flagella are shown in this work and supplemental material illustrating a 3D animation using the obtained experimental results is also included.

Three-dimensional vortex-bright solitons in a spin-orbit-coupled spin-1 condensate

NASA Astrophysics Data System (ADS)

Gautam, Sandeep; Adhikari, S. K.

2018-01-01

We demonstrate stable and metastable vortex-bright solitons in a three-dimensional spin-orbit-coupled three-component hyperfine spin-1 Bose-Einstein condensate (BEC) using numerical solution and variational approximation of a mean-field model. The spin-orbit coupling provides attraction to form vortex-bright solitons in both attractive and repulsive spinor BECs. The ground state of these vortex-bright solitons is axially symmetric for weak polar interaction. For a sufficiently strong ferromagnetic interaction, we observe the emergence of a fully asymmetric vortex-bright soliton as the ground state. We also numerically investigate moving solitons. The present mean-field model is not Galilean invariant, and we use a Galilean-transformed mean-field model for generating the moving solitons.

Microstructural studies of 35 degrees C copper Ni-Ti orthodontic wire and TEM confirmation of low-temperature martensite transformation.

PubMed

Brantley, William A; Guo, Wenhua; Clark, William A T; Iijima, Masahiro

2008-02-01

Previous temperature-modulated differential scanning calorimetry (TMDSC) study of nickel-titanium orthodontic wires revealed a large exothermic low-temperature peak that was attributed to transformation within martensitic NiTi. The purpose of this study was to use transmission electron microscopy (TEM) to verify this phase transformation in a clinically popular nickel-titanium wire, identify its mechanism and confirm other phase transformations found by TMDSC, and to provide detailed information about the microstructure of this wire. The 35 degrees C Copper nickel-titanium wire (Ormco) with cross-section dimensions of 0.016 in. x 0.022 in. used in the earlier TMDSC investigation was selected. Foils were prepared for TEM analyses by mechanical grinding, polishing, dimpling, ion milling and plasma cleaning. Standard bright-field and dark-field TEM images were obtained, along with convergent-beam electron diffraction patterns. A cryo-stage with the electron microscope (Phillips CM 200) permitted the specimen to be observed at -187, -45, and 50 degrees C, as well as at room temperature. Microstructures were also observed with an optical microscope and a scanning electron microscope. Room temperature microstructures had randomly oriented, elongated grains that were twinned. Electron diffraction patterns confirmed that phase transformations took place over temperature ranges previously found by TMDSC. TEM observations revealed a high dislocation density and fine-scale oxide particles, and that twinning is the mechanism for the low-temperature transformation in martensitic NiTi. TEM confirmed the low-temperature peak and other phase transformations observed by TMDSC, and revealed that twinning in martensite is the mechanism for the low-temperature peak. The high dislocation density and fine-scale oxide particles in the microstructure are the result of the wire manufacturing process.

3D imaging of optically cleared tissue using a simplified CLARITY method and on-chip microscopy

PubMed Central

Zhang, Yibo; Shin, Yoonjung; Sung, Kevin; Yang, Sam; Chen, Harrison; Wang, Hongda; Teng, Da; Rivenson, Yair; Kulkarni, Rajan P.; Ozcan, Aydogan

2017-01-01

High-throughput sectioning and optical imaging of tissue samples using traditional immunohistochemical techniques can be costly and inaccessible in resource-limited areas. We demonstrate three-dimensional (3D) imaging and phenotyping in optically transparent tissue using lens-free holographic on-chip microscopy as a low-cost, simple, and high-throughput alternative to conventional approaches. The tissue sample is passively cleared using a simplified CLARITY method and stained using 3,3′-diaminobenzidine to target cells of interest, enabling bright-field optical imaging and 3D sectioning of thick samples. The lens-free computational microscope uses pixel super-resolution and multi-height phase recovery algorithms to digitally refocus throughout the cleared tissue and obtain a 3D stack of complex-valued images of the sample, containing both phase and amplitude information. We optimized the tissue-clearing and imaging system by finding the optimal illumination wavelength, tissue thickness, sample preparation parameters, and the number of heights of the lens-free image acquisition and implemented a sparsity-based denoising algorithm to maximize the imaging volume and minimize the amount of the acquired data while also preserving the contrast-to-noise ratio of the reconstructed images. As a proof of concept, we achieved 3D imaging of neurons in a 200-μm-thick cleared mouse brain tissue over a wide field of view of 20.5 mm2. The lens-free microscope also achieved more than an order-of-magnitude reduction in raw data compared to a conventional scanning optical microscope imaging the same sample volume. Being low cost, simple, high-throughput, and data-efficient, we believe that this CLARITY-enabled computational tissue imaging technique could find numerous applications in biomedical diagnosis and research in low-resource settings. PMID:28819645

Applications and challenges of digital pathology and whole slide imaging.

PubMed

Higgins, C

2015-07-01

Virtual microscopy is a method for digitizing images of tissue on glass slides and using a computer to view, navigate, change magnification, focus and mark areas of interest. Virtual microscope systems (also called digital pathology or whole slide imaging systems) offer several advantages for biological scientists who use slides as part of their general, pharmaceutical, biotechnology or clinical research. The systems usually are based on one of two methodologies: area scanning or line scanning. Virtual microscope systems enable automatic sample detection, virtual-Z acquisition and creation of focal maps. Virtual slides are layered with multiple resolutions at each location, including the highest resolution needed to allow more detailed review of specific regions of interest. Scans may be acquired at 2, 10, 20, 40, 60 and 100 × or a combination of magnifications to highlight important detail. Digital microscopy starts when a slide collection is put into an automated or manual scanning system. The original slides are archived, then a server allows users to review multilayer digital images of the captured slides either by a closed network or by the internet. One challenge for adopting the technology is the lack of a universally accepted file format for virtual slides. Additional challenges include maintaining focus in an uneven sample, detecting specimens accurately, maximizing color fidelity with optimal brightness and contrast, optimizing resolution and keeping the images artifact-free. There are several manufacturers in the field and each has not only its own approach to these issues, but also its own image analysis software, which provides many options for users to enhance the speed, quality and accuracy of their process through virtual microscopy. Virtual microscope systems are widely used and are trusted to provide high quality solutions for teleconsultation, education, quality control, archiving, veterinary medicine, research and other fields.

A Minimal Optical Trapping and Imaging Microscopy System

PubMed Central

Hernández Candia, Carmen Noemí; Tafoya Martínez, Sara; Gutiérrez-Medina, Braulio

2013-01-01

We report the construction and testing of a simple and versatile optical trapping apparatus, suitable for visualizing individual microtubules (∼25 nm in diameter) and performing single-molecule studies, using a minimal set of components. This design is based on a conventional, inverted microscope, operating under plain bright field illumination. A single laser beam enables standard optical trapping and the measurement of molecular displacements and forces, whereas digital image processing affords real-time sample visualization with reduced noise and enhanced contrast. We have tested our trapping and imaging instrument by measuring the persistence length of individual double-stranded DNA molecules, and by following the stepping of single kinesin motor proteins along clearly imaged microtubules. The approach presented here provides a straightforward alternative for studies of biomaterials and individual biomolecules. PMID:23451216

Multimodal computational microscopy based on transport of intensity equation

NASA Astrophysics Data System (ADS)

Li, Jiaji; Chen, Qian; Sun, Jiasong; Zhang, Jialin; Zuo, Chao

2016-12-01

Transport of intensity equation (TIE) is a powerful tool for phase retrieval and quantitative phase imaging, which requires intensity measurements only at axially closely spaced planes without a separate reference beam. It does not require coherent illumination and works well on conventional bright-field microscopes. The quantitative phase reconstructed by TIE gives valuable information that has been encoded in the complex wave field by passage through a sample of interest. Such information may provide tremendous flexibility to emulate various microscopy modalities computationally without requiring specialized hardware components. We develop a requisite theory to describe such a hybrid computational multimodal imaging system, which yields quantitative phase, Zernike phase contrast, differential interference contrast, and light field moment imaging, simultaneously. It makes the various observations for biomedical samples easy. Then we give the experimental demonstration of these ideas by time-lapse imaging of live HeLa cell mitosis. Experimental results verify that a tunable lens-based TIE system, combined with the appropriate postprocessing algorithm, can achieve a variety of promising imaging modalities in parallel with the quantitative phase images for the dynamic study of cellular processes.

Anisotropic interactions of a single spin and dark-spin spectroscopy in diamond

NASA Astrophysics Data System (ADS)

Epstein, R. J.; Mendoza, F. M.; Kato, Y. K.; Awschalom, D. D.

2005-11-01

Experiments on single nitrogen-vacancy (N-V) centres in diamond, which include electron spin resonance, Rabi oscillations, single-shot spin readout and two-qubit operations with a nearby13C nuclear spin, show the potential of this spin system for solid-state quantum information processing. Moreover, N-V centre ensembles can have spin-coherence times exceeding 50 μs at room temperature. We have developed an angle-resolved magneto-photoluminescence microscope apparatus to investigate the anisotropic electron-spin interactions of single N-V centres at room temperature. We observe negative peaks in the photoluminescence as a function of both magnetic-field magnitude and angle that are explained by coherent spin precession and anisotropic relaxation at spin-level anti-crossings. In addition, precise field alignment unmasks the resonant coupling to neighbouring `dark' nitrogen spins, otherwise undetected by photoluminescence. These results demonstrate the capability of our spectroscopic technique for measuring small numbers of dark spins by means of a single bright spin under ambient conditions.

Effect of irradiation on the microstructure and the mechanical properties of oxide dispersion strengthened low activation ferritic/martensitic steel

NASA Astrophysics Data System (ADS)

Ramar, A.; Baluc, N.; Schäublin, R.

2007-08-01

Ferritic/martensitic (F/M) steels show good resistance to swelling and low damage accumulation upon irradiation relative to stainless steels. 0.3 wt% yttria particles were added to the F/M steel EUROFER 97 to produce oxide dispersion strengthened (ODS) steel, to increase the operating temperature as well as mechanical strength. ODS EUROFER 97 was irradiated in the PIREX facility with 590 MeV protons to 0.3, 1 and 2 dpa at 40 °C. Microstructure of the irradiated samples is analyzed in the transmission electron microscope using bright field, dark field and weak beam conditions. The presence of voids and dislocation loops is observed for the higher doses, where as at low dose (0.3 dpa) only small defects with sizes of 1-3 nm are observed as black dots. The relationship between the defect density to dispersoids is measured and the Burgers' vector of dislocation loops is analyzed.

Femtosecond electron imaging of defect-modulated phonon dynamics

PubMed Central

Cremons, Daniel R.; Plemmons, Dayne A.; Flannigan, David J.

2016-01-01

Precise manipulation and control of coherent lattice oscillations via nanostructuring and phonon-wave interference has the potential to significantly impact a broad array of technologies and research areas. Resolving the dynamics of individual phonons in defect-laden materials presents an enormous challenge, however, owing to the interdependent nanoscale and ultrafast spatiotemporal scales. Here we report direct, real-space imaging of the emergence and evolution of acoustic phonons at individual defects in crystalline WSe2 and Ge. Via bright-field imaging with an ultrafast electron microscope, we are able to image the sub-picosecond nucleation and the launch of wavefronts at step edges and resolve dispersion behaviours during propagation and scattering. We discover that the appearance of speed-of-sound (for example, 6 nm ps−1) wavefronts are influenced by spatially varying nanoscale strain fields, taking on the appearance of static bend contours during propagation. These observations provide unprecedented insight into the roles played by individual atomic and nanoscale features on acoustic-phonon dynamics. PMID:27079790

Quantitative comparison of simulated and measured signals in the STEM mode of a SEM

NASA Astrophysics Data System (ADS)

Walker, C. G. H.; Konvalina, I.; Mika, F.; Frank, L.; Müllerová, I.

2018-01-01

The transmission of electrons with energies 15 keV and 30 keV through Si and Au films of 100 nm thickness each have been studied in a Scanning Transmission Electron Microscope. The electrons that were transmitted through the films were detected using a multi-annular photo-detector consisting of a central Bright Field (BF) and several Dark Field (DF) detectors. For the experiment the detector was gradually offset from the axis and the signal from the central BF detector was studied as a function of the offset distance and compared with MC simulations. The experiment showed better agreement between experiment and several different MC simulations as compared to previous results, but differences were still found particularly for low angle scattering from Si. Data from Au suggest that high energy secondary electrons contribute to the signal on the central BF detector for low primary beam energies, when the STEM detector is in its usual central position.

First direct visualization of spillover species emitted from pt nanoparticles.

PubMed

Takakusagi, Satoru; Fukui, Ken-ichi; Tero, Ryugo; Asakura, Kiyotaka; Iwasawa, Yasuhiro

2010-11-02

We studied the methanol adsorption behavior of Pt nanoparticles that were vacuum-deposited on a TiO(2)(110) surface at room temperature by using an ultrahigh vacuum (UHV) scanning tunneling microscope (STM). A large number of bright spots were observed on fivefold-coordinated Ti (Ti(5c)) rows of the TiO(2)(110) surface after exposure of the Pt/TiO(2)(110) to methanol vapor. We assigned the bright spots to methoxy species. These were mobile and were found to hop along the Ti(5c) rows. In situ time-resolved STM observations of the formation and migration of the bright spots on the Pt/TiO(2)(110) were carried out in the presence of methanol. The bright spots were produced at the periphery of the Pt nanoparticles and migrated to the substrate Ti(5c) rows. We discuss the spillover process and behavior of the methoxy species on the Pt/TiO(2)(110).

Immunogold staining procedure for the localisation of regulatory peptides.

PubMed

Varndell, I M; Tapia, F J; Probert, L; Buchan, A M; Gu, J; De Mey, J; Bloom, S R; Polak, J M

1982-01-01

The use of protein A- and IgG-conjugated colloidal gold staining methods for the immuno-localisation of peptide hormones and neurotransmitters at light- and electron microscope level are described and discussed. Bright-field and dark-ground illumination modes have been used to visualise the gold-labelled antigenic sites at the light microscope level. Immunogold staining procedures at the ultrastructural level using region-specific antisera have been adopted to localise specific molecular forms of peptides including gastrin (G17 and G34), glucagon and pro-glucagon, insulin and pro-insulin, in normal tissue and in tumours of the gastroenteropancreatic system. Similar methods have been used to demonstrate the heterogeneity of p-type nerves in the enteric nervous system. Vasoactive intestinal polypeptide (VIP) has been localised to granular sites (mean +/- S.D. granule diameter = 98 +/- 19 nm) in nerve terminals of the enteric plexuses and in tumour cells of diarrhoeogenic VIP-producing neoplasias (mean +/- S.D. granule diameter = 126 +/- 37 nm) using immunogold procedures applied to ultraviolet-cured ultrathin sections. Co-localisation of amines and peptides in carotid body type I cells and in chromaffin cells of normal adrenal medulla and phaeochromocytomas has also been demonstrated. Advantages of the immunogold procedures over alternative immunocytochemical techniques are discussed.

An Innovative Method for Obtaining Consistent Images and Quantification of Histochemically Stained Specimens

PubMed Central

Sedgewick, Gerald J.; Ericson, Marna

2015-01-01

Obtaining digital images of color brightfield microscopy is an important aspect of biomedical research and the clinical practice of diagnostic pathology. Although the field of digital pathology has had tremendous advances in whole-slide imaging systems, little effort has been directed toward standardizing color brightfield digital imaging to maintain image-to-image consistency and tonal linearity. Using a single camera and microscope to obtain digital images of three stains, we show that microscope and camera systems inherently produce image-to-image variation. Moreover, we demonstrate that post-processing with a widely used raster graphics editor software program does not completely correct for session-to-session inconsistency. We introduce a reliable method for creating consistent images with a hardware/software solution (ChromaCal™; Datacolor Inc., NJ) along with its features for creating color standardization, preserving linear tonal levels, providing automated white balancing and setting automated brightness to consistent levels. The resulting image consistency using this method will also streamline mean density and morphometry measurements, as images are easily segmented and single thresholds can be used. We suggest that this is a superior method for color brightfield imaging, which can be used for quantification and can be readily incorporated into workflows. PMID:25575568

On the Progress of Scanning Transmission Electron Microscopy (STEM) Imaging in a Scanning Electron Microscope.

PubMed

Sun, Cheng; Müller, Erich; Meffert, Matthias; Gerthsen, Dagmar

2018-04-01

Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

Analysis of a high brightness photo electron beam with self field and wake field effects

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

Parsa, Z.

High brightness sources are the basic ingredients in the new accelerator developments such as Free-Electron Laser experiments. The effects of the interactions between the highly charged particles and the fields in the accelerating structure, e.g. R.F., Space charge and Wake fields can be detrimental to the beam and the experiments. We present and discuss the formulation used, some simulation and results for the Brookhaven National Laboratory high brightness beam that illustrates effects of the accelerating field, space charge forces (e.g. due to self field of the bunch), and the wake field (e.g. arising from the interaction of the cavity surfacemore » and the self field of the bunch).« less

Measuring protein dynamics in live cells: protocols and practical considerations for fluorescence fluctuation microscopy

PubMed Central

Youker, Robert T.; Teng, Haibing

2014-01-01

Abstract. Quantitative analysis of protein complex stoichiometries and mobilities are critical for elucidating the mechanisms that regulate cellular pathways. Fluorescence fluctuation spectroscopy (FFS) techniques can measure protein dynamics, such as diffusion coefficients and formation of complexes, with extraordinary precision and sensitivity. Complete calibration and characterization of the microscope instrument is necessary in order to avoid artifacts during data acquisition and to capitalize on the full capabilities of FFS techniques. We provide an overview of the theory behind FFS techniques, discuss calibration procedures, provide protocols, and give practical considerations for performing FFS experiments. One important parameter recovered from FFS measurements is the relative molecular brightness that can correlate with oligomerization. Three methods for measuring molecular brightness (fluorescence correlation spectroscopy, photon-counting histogram, and number and brightness analysis) recover similar values when measuring samples under ideal conditions in vitro. However, examples are given illustrating that these different methods used for calculating molecular brightness of fluorescent molecules in cells are not always equivalent. Methods relying on spot measurements are more prone to bleaching and movement artifacts that can lead to underestimation of brightness values. We advocate for the use of multiple FFS techniques to study molecular brightnesses to overcome and compliment limitations of individual techniques. PMID:25260867

Electron-beam irradiation induced transformation of Cu2(OH)3NO3 nanoflakes into nanocrystalline CuO

NASA Astrophysics Data System (ADS)

Padhi, S. K.; Gottapu, S. N.; Krishna, M. Ghanashyam

2016-05-01

The transmission electron microscope electron-beam (TEM e-beam) as a material modification tool has been demonstrated. The material modification is realised in the high-resolution TEM mode (largest condenser aperture, 150 μm, and 200 nm spot size) at a 200 keV beam energy. The Cu2(OH)3NO3 (CHN) nanoflakes used in this study were microwave solution processed that were layered single crystals and radiation sensitive. The single domain CHN flakes disintegrate into a large number of individual CuO crystallites within a 90 s span of time. The sequential bright-field, dark-field, and selected area electron diffraction modes were employed to record the evolved morphology, microstructural changes, and structural transformation that validate CHN modification. High-resolution transmission electron microscopy imaging of e-beam irradiated regions unambiguously supports the growth of CuO nanoparticles (11.8(3.2) nm in diameter). This study demonstrates e-beam irradiation induced CHN depletion, subsequent nucleation and growth of nanocrystalline CuO regions well embedded in the parent burnt porous matrix which can be useful for miniaturized sensing applications. NaBH4 induced room temperature reduction of CHN to elemental Cu and its printability on paper was also demonstrated.The transmission electron microscope electron-beam (TEM e-beam) as a material modification tool has been demonstrated. The material modification is realised in the high-resolution TEM mode (largest condenser aperture, 150 μm, and 200 nm spot size) at a 200 keV beam energy. The Cu2(OH)3NO3 (CHN) nanoflakes used in this study were microwave solution processed that were layered single crystals and radiation sensitive. The single domain CHN flakes disintegrate into a large number of individual CuO crystallites within a 90 s span of time. The sequential bright-field, dark-field, and selected area electron diffraction modes were employed to record the evolved morphology, microstructural changes, and structural transformation that validate CHN modification. High-resolution transmission electron microscopy imaging of e-beam irradiated regions unambiguously supports the growth of CuO nanoparticles (11.8(3.2) nm in diameter). This study demonstrates e-beam irradiation induced CHN depletion, subsequent nucleation and growth of nanocrystalline CuO regions well embedded in the parent burnt porous matrix which can be useful for miniaturized sensing applications. NaBH4 induced room temperature reduction of CHN to elemental Cu and its printability on paper was also demonstrated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02572b

Polarimetry and spectroscopy of a simple sunspot. I - On the magnetic field of a sunspot penumbra

NASA Technical Reports Server (NTRS)

Schmidt, W.; Hofmann, A.; Balthasar, H.; Tarbell, T. D.; Frank, Z. A.

1992-01-01

We investigate the magnetic field structure of a medium sized sunspot using high resolution magnetograms and spectrograms and derive a relationship between the brightness of penumbral structures and the inclination of the magnetic field. The field inclination to the spot normal is larger in the dark structures than in the bright ones. We show that the field strength does not vary between dark and bright structures. At the inner penumbral boundary the field strength is 2000 Gauss and about 1000 Gauss at the outer penumbral edge. The line-of sight component of the material flow decreases rapidly within one arcsecond at the photospheric boundary of the spot.

Note: Tandem Kirkpatrick-Baez microscope with sixteen channels for high-resolution laser-plasma diagnostics

NASA Astrophysics Data System (ADS)

Yi, Shengzhen; Zhang, Zhe; Huang, Qiushi; Zhang, Zhong; Wang, Zhanshan; Wei, Lai; Liu, Dongxiao; Cao, Leifeng; Gu, Yuqiu

2018-03-01

Multi-channel Kirkpatrick-Baez (KB) microscopes, which have better resolution and collection efficiency than pinhole cameras, have been widely used in laser inertial confinement fusion to diagnose time evolution of the target implosion. In this study, a tandem multi-channel KB microscope was developed to have sixteen imaging channels with the precise control of spatial resolution and image intervals. This precise control was created using a coarse assembly of mirror pairs with high-accuracy optical prisms, followed by precise adjustment in real-time x-ray imaging experiments. The multilayers coated on the KB mirrors were designed to have substantially the same reflectivity to obtain a uniform brightness of different images for laser-plasma temperature analysis. The study provides a practicable method to achieve the optimum performance of the microscope for future high-resolution applications in inertial confinement fusion experiments.

Non-interferometric quantitative phase imaging of yeast cells

NASA Astrophysics Data System (ADS)

Poola, Praveen K.; Pandiyan, Vimal Prabhu; John, Renu

2015-12-01

Real-time imaging of live cells is quite difficult without the addition of external contrast agents. Various methods for quantitative phase imaging of living cells have been proposed like digital holographic microscopy and diffraction phase microscopy. In this paper, we report theoretical and experimental results of quantitative phase imaging of live yeast cells with nanometric precision using transport of intensity equations (TIE). We demonstrate nanometric depth sensitivity in imaging live yeast cells using this technique. This technique being noninterferometric, does not need any coherent light sources and images can be captured through a regular bright-field microscope. This real-time imaging technique would deliver the depth or 3-D volume information of cells and is highly promising in real-time digital pathology applications, screening of pathogens and staging of diseases like malaria as it does not need any preprocessing of samples.

Calculation of gyrosynchrotron radiation brightness temperature for outer bright loop of ICME

NASA Astrophysics Data System (ADS)

Sun, Weiying; Wu, Ji; Wang, C. B.; Wang, S.

:Solar polar orbit radio telescope (SPORT) is proposed to detect the high density plasma clouds of outer bright loop of ICMEs from solar orbit with large inclination. Of particular interest is following the propagation of the plasma clouds with remote sensor in radio wavelength band. Gyrosynchrotron emission is a main radio radiation mechanism of the plasma clouds and can provide information of interplanetary magnetic field. In this paper, we statistically analyze the electron density, electron temperature and magnetic field of background solar wind in time of quiet sun and ICMEs propagation. We also estimate the fluctuation range of the electron density, electron temperature and magnetic field of outer bright loop of ICMEs. Moreover, we calculate and analyze the emission brightness temperature and degree of polarization on the basis of the study of gyrosynchrotron emission, absorption and polarization characteristics as the optical depth is less than or equal to 1.

Long-delayed bright dancing sprite with large Horizontal displacement from its parent flash

NASA Astrophysics Data System (ADS)

Yang, Jing; Lu, Gaopeng; Lee, Li-Jou; Feng, Guili

2015-07-01

We reported in this paper the observation of a very bright long-delayed dancing sprite with distinct horizontal displacement from its parent stroke. The dancing sprite lasted only 60 ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large element in the third field, different from other observations where the dancing sprites usually contained multiple elements over a longer time interval, and the sprite shape and brightness in the video field are often similar to the previous fields. The bright sprite was displaced at least 38 km from its parent cloud-to-ground (CG) stroke and occurred over comparatively higher cloud top region. The parent flash of this compact dancing sprite was of positive polarity, with only one return stroke (approximately +24 kA) and obvious continuing current process, and the charge moment change of stroke was small (barely above the threshold for sprite production). All the sprite elements occurred during the continuing current stage, and the bright long-delayed sprite element induced a considerable current pulse. The dancing feature of this sprite may be linked to the electrical charge structure, dynamics and microphysics of parent storm, and the inferred development of parent CG flash was consistent with previous very high-frequency (VHF) observations of lightning in the same region.

Dynamic full-field infrared imaging with multiple synchrotron beams

PubMed Central

Stavitski, Eli; Smith, Randy J.; Bourassa, Megan W.; Acerbo, Alvin S.; Carr, G. L.; Miller, Lisa M.

2013-01-01

Microspectroscopic imaging in the infrared (IR) spectral region allows for the examination of spatially resolved chemical composition on the microscale. More than a decade ago, it was demonstrated that diffraction limited spatial resolution can be achieved when an apertured, single pixel IR microscope is coupled to the high brightness of a synchrotron light source. Nowadays, many IR microscopes are equipped with multi-pixel Focal Plane Array (FPA) detectors, which dramatically improve data acquisition times for imaging large areas. Recently, progress been made toward efficiently coupling synchrotron IR beamlines to multi-pixel detectors, but they utilize expensive and highly customized optical schemes. Here we demonstrate the development and application of a simple optical configuration that can be implemented on most existing synchrotron IR beamlines in order to achieve full-field IR imaging with diffraction-limited spatial resolution. Specifically, the synchrotron radiation fan is extracted from the bending magnet and split into four beams that are combined on the sample, allowing it to fill a large section of the FPA. With this optical configuration, we are able to oversample an image by more than a factor of two, even at the shortest wavelengths, making image restoration through deconvolution algorithms possible. High chemical sensitivity, rapid acquisition times, and superior signal-to-noise characteristics of the instrument are demonstrated. The unique characteristics of this setup enabled the real time study of heterogeneous chemical dynamics with diffraction-limited spatial resolution for the first time. PMID:23458231

Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

PubMed

Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

2015-02-01

We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of <100 nm. In order to demonstrate the spatiotemporal magnetic imaging capability of this microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz.

Transmission Electron Microscopy | Materials Science | NREL

Science.gov Websites

bright-field images and bright in dark-field images. It is particularly useful for imaging non , because when an experimental image is recorded one loses phase information, and this means one cannot

A superior bright NIR luminescent nanoparticle preparation and indicating calcium signaling detection in cells and small animals.

PubMed

Zhang, Jian; Lakowicz, Joseph R

2018-01-01

Near-field fluorescence (NFF) effects were employed to develop a novel near-infrared (NIR) luminescent nanoparticle (LNP) with superior brightness. The LNP is used as imaging contrast agent for cellular and small animal imaging and furthermore suggested to use for detecting voltage-sensitive calcium in living cells and animals with high sensitivity. NIR Indocyanine green (ICG) dye was conjugated with human serum albumin (HSA) followed by covalently binding to gold nanorod (AuNR). The AuNR displayed dual plasmons from transverse and longitudinal axis, and the longitudinal plasmon was localized at the NIR region which could efficiently couple with the excitation and emission of ICG dye leading to a largely enhanced NFF. The enhancement factor was measured to be about 16-fold using both ensemble and single nanoparticle spectral methods. As an imaging contrast agent, the ICG-HSA-Au complex (abbreviate as ICG-Au) was conjugated on HeLa cells and fluorescence cell images were recorded on a time-resolved confocal microscope. The emission signals of ICG-Au complexes were distinctly resolved as the individual spots that were observed over the cellular backgrounds due to their strong brightness as well as shortened lifetime. The LNPs were also tested to have a low cytotoxicity. The ICG-Au complexes were injected below the skin surface of mouse showing emission spots 5-fold brighter than those from the same amount of free ICG-HSA conjugates. Based on the observations in this research, the excitation and emission of NIR ICG dyes were found to be able to sufficiently couple with the longitudinal plasmon of AuNRs leading to a largely enhanced NFF. Using the LNP with super-brightness as a contrast agent, the ICG-Au complex could be resolved from the background in the cell and small animal imaging. The novel NIR LNP has also a great potential for detection of voltage-gated calcium concentration in the cell and living animal with a high sensitivity.

The Peculiar Solar Minimum 23/24 Revealed by the Microwave Butterfly Diagram

NASA Technical Reports Server (NTRS)

Gopalswamy, Natchimuthuk; Yashiro, Seiji; Makela, Pertti; Shibasaki, Kiyoto; Hathaway, David

2010-01-01

The diminished polar magnetic field strength during the minimum between cycles 23 and 24 is also reflected in the thermal radio emission originating from the polar chromosphere. During solar minima, the polar corona has extended coronal holes containing intense unipolar flux. In microwave images, the coronal holes appear bright, with a brightness enhancement of 500 to 2000 K with respect to the quiet Sun. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is approx.10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approx.250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes..

Brightness discrimination and contrast sensitivity in chronic glaucoma--a clinical study.

PubMed

Teoh, S L; Allan, D; Dutton, G N; Foulds, W S

1990-04-01

The visual acuity, the difference in sensitivity of the two eyes to light (brightness ratio), and contrast sensitivity were assessed in 28 patients with chronic open angle glaucoma and compared with those of 41 normal controls of similar ages and visual acuity. The results obtained were related to the results of Tübingen visual field analysis in patients with glaucoma. Twenty-four of the 28 glaucoma patients (86%) had a significant disparity in brightness ratio between the two eyes. This was found to match the frequency of visual field loss. Moreover, there was a significant relationship between the interocular differences in brightness sense and the difference in the degree of visual field loss between the two eyes. Of the glaucoma patients 39% had sum contrast sensitivities outside the normal range for age-matched normal controls. No significant correlation was found between the interocular difference in brightness sense and the visual acuity or the interocular difference in sum contrast sensitivity. It is concluded that, in the presence of a normal visual acuity, the brightness ratio test warrants evaluation as a potential screening test for chronic open angle glaucoma.

Fluorescence histochemical and elec-ron microscopical observations on sympathetic ganglia of the chick embryo cultured with and without hydrocortisone.

PubMed

Hervonen, H; Eränkö, O

1975-01-01

Lumbar sympathetic ganglia of 12-day-old chick embryos were cultured in organ cultures for 14 days with 1, 10 or 100 mg/l of hydrocortisone or without it. Catecholamines were demonstrated by the formaldehyde-induced fluorescence method. For electron microscopy, the cultures were fixed with glutarialdehyde and osmium tetroxide. Two types of cells with catecholamine fluoresecence were observed in the control cultures: (1) weakly fluorescent sympathetic neurons and sympathicoblasts with long nerve fibres, which were the most common cell type in the explant, and (2) brightly fluorescent cells with or without fluorescent processes, which were less common and were scattered in the explant. Hydrocortisone caused a great increase in the number of the brightly fluorescent cells. With 10 mg/l of hydrocortisone the increase was about ten-fold as compared with the control cultures. There was no change in the morphology of the cells, nor could any change be observed in the fluorescence intensity by eye. Electron microscopically the mature neurons were the most common cell type on the surface of the culture, while more immature sympathicoblasts were seen in the deeper layers. Cells were also found which contained large numbers of catecholamine-strong granular vesicles 105-275 nm in diameter. These cells were infrequent. They had round vesicular nuclei and resembled also in other respects sympathicoblasts or young nerve cells. One such cell was found in mitotic division by electron microscopy. Hydrocortisone caused a marked increase in the number of these granule-containing cells and their processes. Cells which could have been classified as the small intensely fluorescent cells of the mammalian ganglion type or their electron microscopic equivalent, the granule-containing cells were found neither in the control cultures nor in the hydrocortisone-containing cultures. It is concluded that most brightly fluorescent cells in cultured sympathetic ganglia of the chick are nerve cells or sympathicoblasts rich in amine-storing granular vesicles.

Dark-field image contrast in transmission scanning electron microscopy: Effects of substrate thickness and detector collection angle.

PubMed

Woehl, Taylor; Keller, Robert

2016-12-01

An annular dark field (ADF) detector was placed beneath a specimen in a field emission scanning electron microscope operated at 30kV to calibrate detector response to incident beam current, and to create transmission images of gold nanoparticles on silicon nitride (SiN) substrates of various thicknesses. Based on the linear response of the ADF detector diodes to beam current, we developed a method that allowed for direct determination of the percentage of that beam current forward scattered to the ADF detector from the sample, i.e. the transmitted electron (TE) yield. Collection angles for the ADF detector region were defined using a masking aperture above the detector and were systematically varied by changing the sample to detector distance. We found the contrast of the nanoparticles, relative to the SiN substrate, decreased monotonically with decreasing inner exclusion angle and increasing substrate thickness. We also performed Monte Carlo electron scattering simulations, which showed quantitative agreement with experimental contrast associated with the nanoparticles. Together, the experiments and Monte Carlo simulations revealed that the decrease in contrast with decreasing inner exclusion angle was due to a rapid increase in the TE yield of the low atomic number substrate. Nanoparticles imaged at low inner exclusion angles (<150mrad) and on thick substrates (>50nm) showed low image contrast in their centers surrounded by a bright high-contrast halo on their edges. This complex image contrast was predicted by Monte Carlo simulations, which we interpreted in terms of mixing of the nominally bright field (BF) and ADF electron signals. Our systematic investigation of inner exclusion angle and substrate thickness effects on ADF t-SEM imaging provides fundamental understanding of the contrast mechanisms for image formation, which in turn suggest practical limitations and optimal imaging conditions for different substrate thicknesses. Copyright © 2016. Published by Elsevier B.V.

Sub-micron materials characterization using near-field optics

NASA Astrophysics Data System (ADS)

Blodgett, David Wesley

1998-12-01

High-resolution sub-surface materials characterization and inspection are critical in the microelectronics and thin films industries. To this end, a technique is described that couples the bulk property measurement capabilities of high-frequency ultrasound with the high-resolution surface imaging capabilities of the near-field optical microscope. Sensing bulk microstructure variations in the material, such as grain boundaries, requires a detection footprint smaller than the variation itself. The near-field optical microscope, with the ability to exceed the diffraction limit in optical resolution, meets this requirement. Two apertureless near-field optical microscopes, on-axis and off-axis illumination, have been designed and built. Near-field and far-field approach curves for both microscopes are presented. The sensitivity of the near-field approach curve was 8.3 muV/nm. Resolution studies for the near-field microscope indicate optical resolutions on the order of 50 nm, which exceeds the diffraction limit. The near-field microscope has been adapted to detect both contact-transducer-generated and laser-generated ultrasound. The successful detection of high-frequency ultrasound with the near-field optical microscope demonstrates the potential of this technique.

Spatiotemporal analysis of brightness induction

PubMed Central

McCourt, Mark E.

2011-01-01

Brightness induction refers to a class of visual illusions in which the perceived intensity of a region of space is influenced by the luminance of surrounding regions. These illusions are significant because they provide insight into the neural organization of the visual system. A novel quadrature-phase motion cancelation technique was developed to measure the magnitude of the grating induction brightness illusion across a wide range of spatial frequencies, temporal frequencies and test field heights. Canceling contrast is greatest at low frequencies and declines with increasing frequency in both dimensions, and with increasing test field height. Canceling contrast scales as the product of inducing grating spatial frequency and test field height (the number of inducing grating cycles per test field height). When plotted using a spatial axis which indexes this product, the spatiotemporal induction surfaces for four test field heights can be described as four partially overlapping sections of a single larger surface. These properties of brightness induction are explained in the context of multiscale spatial filtering. The present study is the first to measure the magnitude of grating induction as a function of temporal frequency. Taken in conjunction with several other studies (Blakeslee & McCourt, 2008; Robinson & de Sa, 2008; Magnussen & Glad, 1975) the results of this study illustrate that at least one form of brightness induction is very much faster than that reported by DeValois et al. (1986) and Rossi and Paradiso (1996), and are inconsistent with the proposition that brightness induction results from a slow “filling in” process. PMID:21763339

Long-delayed bright dancing sprite with large horizontal displacement from its parent flash

NASA Astrophysics Data System (ADS)

Yang, J.; Lu, G.; Lee, L. J.; Feng, G.

2015-12-01

A long-delayed very bright dancing sprite with large horizontal displacement from its parent flash was observed. The dancing sprite lasted only 60 ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large sprite element in the third field, different from other observations. The bright sprite displaced at least 38 km from its parent flash and occurred over comparatively higher cloud top region. The parent flash was positive, with only one return stroke (~24 kA) and obvious continuing current process, and the charge moment change of the stroke was small (roughly the threshold for sprite production). All of the sprite elements occurred during the continuing current period, and the bright sprite induced considerable current. The sprite dancing features may be linked to parent storm electrical structure, dynamics and microphysics, and the parent CG discharge process which was consistent with VHF observations.

Control of excitation in the fluorescence microscope.

PubMed

Lea, D J; Ward, D J

1979-01-01

In fluorescence microscopy image brightness and contrast and the rate of fading depend upon the intensity of illumination of the specimen. An iris diaphragm or neutral density filters may be used to reduce fluorescence excitation. Also the excitation bandwidth may be varied by using a broad band exciter filter with a set of interchangeable yellow glass filters at the lamphouse.

Application of low-energy scanning transmission electron microscopy for the study of Pt-nanoparticle uptake in human colon carcinoma cells.

PubMed

Blank, Holger; Schneider, Reinhard; Gerthsen, Dagmar; Gehrke, Helge; Jarolim, Katharina; Marko, Doris

2014-06-01

High-angle annular dark-field scanning transmission electron microscopy (HAADF STEM) in a scanning electron microscope facilitates the acquisition of images with high chemical sensitivity and high resolution. HAADF STEM at low electron energies is particularly suited to image nanoparticles (NPs) in thin cell sections which are not subjected to poststaining procedures as demonstrated by comparison with bright-field TEM. High membrane contrast is achieved and distinction of NPs with different chemical composition is possible at first sight. Low-energy HAADF STEM was applied to systematically study the uptake of Pt-NPs with a broad size distribution in HT29 colon carcinoma cells as a function of incubation time and incubation temperature. The cellular dose was quantified, that is, the amount and number density of NPs taken up by the cells, as well as the particle-size distribution. The results show a strong dependence of the amount of incubated NPs on the exposure time which can be understood by considering size-dependent diffusion and gravitational settling of the NPs in the cell culture medium.

Wafer defect detection by a polarization-insensitive external differential interference contrast module.

PubMed

Nativ, Amit; Feldman, Haim; Shaked, Natan T

2018-05-01

We present a system that is based on a new external, polarization-insensitive differential interference contrast (DIC) module specifically adapted for detecting defects in semiconductor wafers. We obtained defect signal enhancement relative to the surrounding wafer pattern when compared with bright-field imaging. The new DIC module proposed is based on a shearing interferometer that connects externally at the output port of an optical microscope and enables imaging thin samples, such as wafer defects. This module does not require polarization optics (such as Wollaston or Nomarski prisms) and is insensitive to polarization, unlike traditional DIC techniques. In addition, it provides full control of the DIC shear and orientation, which allows obtaining a differential phase image directly on the camera (with no further digital processing) while enhancing defect detection capabilities, even if the size of the defect is smaller than the resolution limit. Our technique has the potential of future integration into semiconductor production lines.

High-resolution x-ray tomography using laboratory sources

NASA Astrophysics Data System (ADS)

Tkachuk, Andrei; Feser, Michael; Cui, Hongtao; Duewer, Fred; Chang, Hauyee; Yun, Wenbing

2006-08-01

X-ray computed tomography (XCT) is a powerful nondestructive 3D imaging technique, which enables the visualization of the three dimensional structure of complex, optically opaque samples. High resolution XCT using Fresnel zone plate lenses has been confined in the past to synchrotron radiation centers due to the need for a bright and intense source of x-rays. This confinement severely limits the availability and accessibility of x-ray microscopes and the wide proliferation of this methodology. We are describing a sub-50nm resolution XCT system operating at 8 keV in absorption and Zernike phase contrast mode based on a commercially available laboratory x-ray source. The system utilizes high-efficiency Fresnel zone plates with an outermost zone width of 35 nm and 700 nm structure height resulting in a current spatial resolution better than 50 nm. In addition to the technical description of the system and specifications, we present application examples in the semiconductor field.

Brightness discrimination test is not useful in screening for open angle glaucoma.

PubMed

Peter, E; Thomas, R; Muliyil, J

1996-06-01

Brightness discrimination test (BDT) is routinely employed to assess asymmetrical optic nerve dysfunction and has been suggested as a screening test for primary open angle glaucoma (POAG). We tested the reliability and validity of BDT in the diagnosis of POAG. The study groups included 34 patients with established primary open angle glaucoma, 20 glaucoma suspects, and 33 age-sex matched controls. Cataract was not an exclusion criterion in these groups. The normal brightness score was determined to be 88% (mean score, 94%-2 SD) in a pilot study. Brightness discrimination test was performed in all subjects by two observers independently. BDT showed an excellent interobserver agreement (weighted Kappa 0.84). The presence of a cataract alone increased the risk of brightness impairment twofold, glaucoma alone increased the risk eightfold, and the presence of both conditions by 17 times compared to those with neither condition. BDT was not a useful test in the diagnosis of POAG (sensitivity 67% and specificity 93%); the ability to detect a significant field defect was also poor (sensitivity 53% and specificity 76%). There was poor association between decreased brightness scores and asymmetrical field defects as determined by the Humphrey's field analyzer (HFA).

Brightness discrimination and contrast sensitivity in chronic glaucoma--a clinical study.

PubMed Central

Teoh, S L; Allan, D; Dutton, G N; Foulds, W S

1990-01-01

The visual acuity, the difference in sensitivity of the two eyes to light (brightness ratio), and contrast sensitivity were assessed in 28 patients with chronic open angle glaucoma and compared with those of 41 normal controls of similar ages and visual acuity. The results obtained were related to the results of Tübingen visual field analysis in patients with glaucoma. Twenty-four of the 28 glaucoma patients (86%) had a significant disparity in brightness ratio between the two eyes. This was found to match the frequency of visual field loss. Moreover, there was a significant relationship between the interocular differences in brightness sense and the difference in the degree of visual field loss between the two eyes. Of the glaucoma patients 39% had sum contrast sensitivities outside the normal range for age-matched normal controls. No significant correlation was found between the interocular difference in brightness sense and the visual acuity or the interocular difference in sum contrast sensitivity. It is concluded that, in the presence of a normal visual acuity, the brightness ratio test warrants evaluation as a potential screening test for chronic open angle glaucoma. PMID:2186795

Enhancing the Detection of Dysmorphic Red Blood Cells and Renal Tubular Epithelial Cells with a Modified Urinalysis Protocol.

PubMed

Chu-Su, Yu; Shukuya, Kenichi; Yokoyama, Takashi; Lin, Wei-Chou; Chiang, Chih-Kang; Lin, Chii-Wann

2017-01-11

Urinary sediment is used to evaluate patients with possible urinary tract diseases. Currently, numerous protocols are applied to detect dysmorphic red blood cells (RBCs) and renal tubular epithelial cells (RTECs) in urinary sediment. However, distinct protocols are used by nephrologists and medical technologists for specimen concentration and observation, which leads to major discrepancies in the differential counts of formed elements such as dysmorphic RBCs and RTECs and might interfere with an accurate clinical diagnosis. To resolve these problems, we first tested a modified urinalysis protocol with an increased relative centrifuge force and concentration factor in 20 biopsy-confirmed glomerulonephritis patients with haematuria. We successfully improved the recovery ratio of dysmorphic RBCs in clinical specimens from 34.7% to 42.0% (P < 0.001). Furthermore, we confirmed the correlation between counts by the modified urinary protocol and Sysmex UF-1000i urinary flow cytometer (r ≥ 0.898, P < 0.001). A total of 28 types of isomorphic and dysmorphic RBCs were detected using a bright field microscope, with results comparable to those using a standard phase contrast microscope. Finally, we applied Sternheimer stain to enhance the contrast of RTECs in the urinary sediments. We concluded that this modified urinalysis protocol significantly enhanced the quality of urinalysis.

Enhancing the Detection of Dysmorphic Red Blood Cells and Renal Tubular Epithelial Cells with a Modified Urinalysis Protocol

PubMed Central

Chu-Su, Yu; Shukuya, Kenichi; Yokoyama, Takashi; Lin, Wei-Chou; Chiang, Chih-Kang; Lin, Chii-Wann

2017-01-01

Urinary sediment is used to evaluate patients with possible urinary tract diseases. Currently, numerous protocols are applied to detect dysmorphic red blood cells (RBCs) and renal tubular epithelial cells (RTECs) in urinary sediment. However, distinct protocols are used by nephrologists and medical technologists for specimen concentration and observation, which leads to major discrepancies in the differential counts of formed elements such as dysmorphic RBCs and RTECs and might interfere with an accurate clinical diagnosis. To resolve these problems, we first tested a modified urinalysis protocol with an increased relative centrifuge force and concentration factor in 20 biopsy-confirmed glomerulonephritis patients with haematuria. We successfully improved the recovery ratio of dysmorphic RBCs in clinical specimens from 34.7% to 42.0% (P < 0.001). Furthermore, we confirmed the correlation between counts by the modified urinary protocol and Sysmex UF-1000i urinary flow cytometer (r ≥ 0.898, P < 0.001). A total of 28 types of isomorphic and dysmorphic RBCs were detected using a bright field microscope, with results comparable to those using a standard phase contrast microscope. Finally, we applied Sternheimer stain to enhance the contrast of RTECs in the urinary sediments. We concluded that this modified urinalysis protocol significantly enhanced the quality of urinalysis. PMID:28074941

Automated classification of bone marrow cells in microscopic images for diagnosis of leukemia: a comparison of two classification schemes with respect to the segmentation quality

NASA Astrophysics Data System (ADS)

Krappe, Sebastian; Benz, Michaela; Wittenberg, Thomas; Haferlach, Torsten; Münzenmayer, Christian

2015-03-01

The morphological analysis of bone marrow smears is fundamental for the diagnosis of leukemia. Currently, the counting and classification of the different types of bone marrow cells is done manually with the use of bright field microscope. This is a time consuming, partly subjective and tedious process. Furthermore, repeated examinations of a slide yield intra- and inter-observer variances. For this reason an automation of morphological bone marrow analysis is pursued. This analysis comprises several steps: image acquisition and smear detection, cell localization and segmentation, feature extraction and cell classification. The automated classification of bone marrow cells is depending on the automated cell segmentation and the choice of adequate features extracted from different parts of the cell. In this work we focus on the evaluation of support vector machines (SVMs) and random forests (RFs) for the differentiation of bone marrow cells in 16 different classes, including immature and abnormal cell classes. Data sets of different segmentation quality are used to test the two approaches. Automated solutions for the morphological analysis for bone marrow smears could use such a classifier to pre-classify bone marrow cells and thereby shortening the examination duration.

Imaging slit-coupled surface plasmon polaritons using conventional optical microscopy.

PubMed

Mehfuz, R; Chowdhury, F A; Chau, K J

2012-05-07

We develop a technique that now enables surface plasmon polaritons (SPPs) coupled by nano-patterned slits in a metal film to be detected using conventional optical microscopy with standard objective lenses. The crux of this method is an ultra-thin polymer layer on the metal surface, whose thickness can be varied over a nanoscale range to enable controllable tuning of the SPP momentum. At an optimal layer thickness for which the SPP momentum matches the momentum of light emerging from the slit, the SPP coupling efficiency is enhanced about six times relative to that without the layer. The enhanced efficiency results in distinctive and bright plasmonic signatures near the slit visible by naked eye under an optical microscope. We demonstrate how this capability can be used for parallel measurement through a simple experiment in which the SPP propagation distance is extracted from a single microscope image of an illuminated array of nano-patterned slits on a metal surface. We also use optical microscopy to image the focal region of a plasmonic lens and obtain results consistent with a previously-reported results using near-field optical microscopy. Measurement of SPPs near a nano-slit using conventional and widely-available optical microscopy is an important step towards making nano-plasmonic device technology highly accessible and easy-to-use.

Applications of Real Space Crystallography in Characterization of Dislocations in Geological Materials in a Scanning Electron Microscope (SEM)

NASA Astrophysics Data System (ADS)

Kaboli, S.; Burnley, P. C.

2017-12-01

Imaging and characterization of defects in crystalline materials is of significant importance in various disciplines including geoscience, materials science, and applied physics. Linear defects such as dislocations and planar defects such as twins and stacking faults, strongly influence many of the properties of crystalline materials and also reflect the conditions and degree of deformation. Dislocations have been conventionally imaged in thin foils in a transmission electron microscope (TEM). Since the development of field emission scanning electron microscopes (FE-SEM) with high gun brightness and small spot size, extensive efforts have been dedicated to the imaging and characterization of dislocations in semi-conductors using electron channeling contrast imaging (ECCI) in the SEM. The obvious advantages of using SEM over TEM include easier and non-destructive sample preparation and a large field of view enabling statistical examination of the density and distribution of dislocations and other defects. In this contribution, we extend this technique to geological materials and introduce the Real Space Crystallography methodology for imaging and complete characterization of dislocations based on bend contour contrast obtained by ECCI in FE-SEM. Bend contours map out the distortion in the crystal lattice across a deformed grain. The contrast of dislocations is maximum in the vicinity of bend contours where crystal planes diffract at small and positive deviations from the Bragg positions (as defined by Bragg's law of electron diffraction). Imaging is performed in a commercial FE-SEM equipped with a standard silicon photodiode backscattered (BSE) detector and an electron backscatter diffraction (EBSD) system for crystal orientation measurements. We demonstrate the practice of this technique in characterization of a number of geological materials in particular quartz, forsterite olivine and corundum, experimentally deformed at high pressure-temperature conditions. This new approach in microstructure characterization of deformed geologic materials in FE-SEM, without the use of etching or decoration techniques, has valuable applications to both experimentally deformed and naturally deformed specimens.

RGB digital lensless holographic microscopy

NASA Astrophysics Data System (ADS)

Garcia-Sucerquia, Jorge

2013-11-01

The recent introduction of color digital lensless holographic microscopy (CDLHM) has shown the possibility of imaging microscopic specimens at full color without the need of lenses. Owing to the simplicity, robustness, and compactness of the digital lensless holographic microscopes (DLHM), they have been presented as the ideal candidates to being developed into portable holographic microscopes. However, in the case of CDLHM the utilization of three independent lasers hinders the portability option for this microscope. In this contribution an alternative to reduce the complexity of CDLHM aimed to recover the portability of this microscopy technology is presented. A super-bright white-light light-emitting diode (LED) is spectrally and spatially filtered to produce the needed illumination by CDLHM to work. CDLHM with LED illumination is used to image at full color a section of the head of a drosophila melanogaster fly (fruit fly). The LED-CDLHM method shows the capability of imaging objects of 2μm size in comparison with the micrometer resolution reported for LASER-CDLHM.

Training Medical Novices in Spinal Microsurgery: Does the Modality Matter? A Pilot Study Comparing Traditional Microscopic Surgery and a Novel Robotic Optoelectronic Visualization Tool

PubMed Central

Tubbs, R. Shane; Page, Jeni; Chapman, Alexandra; Burgess, Brittni; Laws, Tyler; Warren, Haylie; Oskouian, Rod J

2016-01-01

The operative microscope has been a staple instrument in the neurosurgical operating room over the last 50 years. With advances in optoelectronics, options such as robotically controlled high magnification have become available. Such robotically controlled optoelectronic systems may offer new opportunities in surgical technique and teaching. However, traditionally trained surgeons may find it hard to accept newer technologies due to an inherent bias emerging from their previous background. We, therefore, studied how a medically naïve population in a pilot study would meet set microsurgical goals in a cadaver experiment using either a conventional operative microscope or BrightMatter™ Servo system, ​a robotically controlled optoelectronic system (Synaptive Medical, Toronto, Ontario, Canada). We found that the relative ease in teaching medical novices with a robotically controlled optoelectronic system was more valuable when compared to using a modern-day surgical microscope. PMID:26973804

A microscopic study investigating the structure of SnSe surfaces

NASA Astrophysics Data System (ADS)

Kim, Sang-ui; Duong, Anh-Tuan; Cho, Sunglae; Rhim, S. H.; Kim, Jungdae

2016-09-01

SnSe has been widely studied due to its many potential applications that take advantage of its excellent thermoelectric, photovoltaic, and optoelectronic properties. However, experimental investigations into the microscopic structure of SnSe remain largely unexplored. Herein, for the first time, the atomic and electronic structures of SnSe surfaces are studied by a home-built low temperature scanning tunneling microscope (STM) and density functional theory (DFT) calculations. The cleaved surface of SnSe is comprised of covalently bonded Se and Sn atoms in zigzag patterns. However, rectangular periodicity was observed in the atomic images of SnSe surfaces for filled and empty state probing. Detailed atomic structures are analyzed by DFT calculations, indicating that the bright extrusions of both filled and empty state images are mostly located at the positions of Sn atoms.

THE DISCOVERY OF SEVEN EXTREMELY LOW SURFACE BRIGHTNESS GALAXIES IN THE FIELD OF THE NEARBY SPIRAL GALAXY M101

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

Merritt, Allison; Van Dokkum, Pieter; Abraham, Roberto, E-mail: allison.merritt@yale.edu

2014-06-01

Dwarf satellite galaxies are a key probe of dark matter and of galaxy formation on small scales and of the dark matter halo masses of their central galaxies. They have very low surface brightness, which makes it difficult to identify and study them outside of the Local Group. We used a low surface brightness-optimized telescope, the Dragonfly Telephoto Array, to search for dwarf galaxies in the field of the massive spiral galaxy M101. We identify seven large, low surface brightness objects in this field, with effective radii of 10-30 arcseconds and central surface brightnesses of μ {sub g} ∼ 25.5-27.5 magmore » arcsec{sup –2}. Given their large apparent sizes and low surface brightnesses, these objects would likely be missed by standard galaxy searches in deep fields. Assuming the galaxies are dwarf satellites of M101, their absolute magnitudes are in the range –11.6 ≲ M{sub V} ≲ –9.3 and their effective radii are 350 pc-1.3 kpc. Their radial surface brightness profiles are well fit by Sersic profiles with a very low Sersic index (n ∼ 0.3-0.7). The properties of the sample are similar to those of well-studied dwarf galaxies in the Local Group, such as Sextans I and Phoenix. Distance measurements are required to determine whether these galaxies are in fact associated with M101 or are in its foreground or background.« less

Control and acquisition systems for new scanning transmission x-ray microscopes at Advanced Light Source (abstract)

NASA Astrophysics Data System (ADS)

Tyliszczak, T.; Hitchcock, P.; Kilcoyne, A. L. D.; Ade, H.; Hitchcock, A. P.; Fakra, S.; Steele, W. F.; Warwick, T.

2002-03-01

Two new scanning x-ray transmission microscopes are being built at beamline 5.3.2 and beamline 7.0 of the Advanced Light Source that have novel aspects in their control and acquisition systems. Both microscopes use multiaxis laser interferometry to improve the precision of pixel location during imaging and energy scans as well as to remove image distortions. Beam line 5.3.2 is a new beam line where the new microscope will be dedicated to studies of polymers in the 250-600 eV energy range. Since this is a bending magnet beam line with lower x-ray brightness than undulator beam lines, special attention is given to the design not only to minimize distortions and vibrations but also to optimize the controls and acquisition to improve data collection efficiency. 5.3.2 microscope control and acquisition is based on a PC computer running WINDOWS 2000. All mechanical stages are moved by stepper motors with rack mounted controllers. A dedicated counter board is used for counting and timing and a multi-input/output board is used for analog acquisition and control of the focusing mirror. A three axis differential laser interferometer is being used to improve stability and precision by careful tracking of the relative positions of the sample and zone plate. Each axis measures the relative distance between a mirror placed on the sample stage and a mirror attached to the zone plate holder. Agilent Technologies HP 10889A servo-axis interferometer boards are used. While they were designed to control servo motors, our tests show that they can be used to directly control the piezo stage. The use of the interferometer servo-axis boards provides excellent point stability for spectral measurements. The interferometric feedback also provides active vibration isolation which reduces deleterious impact of mechanical vibrations up to 20-30 Hz. It also can improve the speed and precision of image scans. Custom C++ software has been written to provide user friendly control of the microscope and integration with visual light microscopy indexing of the samples. The beam line 7.0 microscope upgrade is a new design which will replace the existing microscope. The design is similar to that of beam line 5.3.2, including interferometric position encoding. However the acquisition and control is based on VXI systems, a Sun computer, and LABVIEW™ software. The main objective of the BL 7.0 microscope upgrade is to achieve precise image scans at very high speed (pixel dwells as short as 10 μs) to take full advantage of the high brightness of the 7.0 undulator beamline. Results of tests and a discussion of the benefits of our scanning microscope designs will be presented.

Polar Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D.

2010-01-01

Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approximately 250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes.

Application of line-scanning microscopy using a linear sensor in semiconductor industry: shape and thickness measurements

NASA Astrophysics Data System (ADS)

Macedo, Milton P.; Correia, C. M. B. A.

2013-04-01

This work aims at showing the applicability of a scanning-stage bench-microscope in bright-field reflection mode for wirebonding inspection of integrated circuits (IC) as well as quality assurance of tracks in printed circuit boards (PCB). The main issues of our laboratorial prototype arise from the use of a linear image sensor taking advantage of its geometry to achieve lower acquisition time in comparison to traditional (pinhole) confocal approach. The use of a slit-detector is normally related to resolution degradation for details parallel to sensor. But an improvement will surely arise using light distribution along line pixels of the sensor which establishes a great advantage in comparison to (pure) slit detectors. The versatility of this bench-microscope affords excellent means to develop and test algorithms. Those to improve lateral resolution isotropy as well as image visualization and 3D mesh reconstruction under different setups namely illumination modes. Based on the results of these tests tests both wide-field illumination and parallel slit illumination and detection configurations were used in these two applications. Results from IC wire-bonding show the ability of the system to extract 3D information. A comparison of auto-focus images and 3D profiles obtained using different 3D reconstruction algorithms as well as a method for the determination of the diameter of the bond wire are presented. Measurements of PCB track width and thickness were performed and the comparison of these results from both longitudinal and transverse tracks stress the limitations of a lower spatial sampling rate induced by the resolution of object stage positioners.

Auto-FPFA: An Automated Microscope for Characterizing Genetically Encoded Biosensors.

PubMed

Nguyen, Tuan A; Puhl, Henry L; Pham, An K; Vogel, Steven S

2018-05-09

Genetically encoded biosensors function by linking structural change in a protein construct, typically tagged with one or more fluorescent proteins, to changes in a biological parameter of interest (such as calcium concentration, pH, phosphorylation-state, etc.). Typically, the structural change triggered by alterations in the bio-parameter is monitored as a change in either fluorescent intensity, or lifetime. Potentially, other photo-physical properties of fluorophores, such as fluorescence anisotropy, molecular brightness, concentration, and lateral and/or rotational diffusion could also be used. Furthermore, while it is likely that multiple photo-physical attributes of a biosensor might be altered as a function of the bio-parameter, standard measurements monitor only a single photo-physical trait. This limits how biosensors are designed, as well as the accuracy and interpretation of biosensor measurements. Here we describe the design and construction of an automated multimodal-microscope. This system can autonomously analyze 96 samples in a micro-titer dish and for each sample simultaneously measure intensity (photon count), fluorescence lifetime, time-resolved anisotropy, molecular brightness, lateral diffusion time, and concentration. We characterize the accuracy and precision of this instrument, and then demonstrate its utility by characterizing three types of genetically encoded calcium sensors as well as a negative control.

Coherence of a spin-polarized electron beam emitted from a semiconductor photocathode in a transmission electron microscope

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

Kuwahara, Makoto, E-mail: kuwahara@esi.nagoya-u.ac.jp; Saitoh, Koh; Tanaka, Nobuo

2014-11-10

The brightness and interference fringes of a spin-polarized electron beam extracted from a semiconductor photocathode excited by laser irradiation are directly measured via its use in a transmission electron microscope. The brightness was 3.8 × 10{sup 7 }A cm{sup −2 }sr{sup −1} for a 30-keV beam energy with the polarization of 82%, which corresponds to 3.1 × 10{sup 8 }A cm{sup −2 }sr{sup −1} for a 200-keV beam energy. The resulting electron beam exhibited a long coherence length at the specimen position due to the high parallelism of (1.7 ± 0.3) × 10{sup −5 }rad, which generated interference fringes representative of a first-order correlation using an electron biprism. The beam also had amore » high degeneracy of electron wavepacket of 4 × 10{sup −6}. Due to the high polarization, the high degeneracy and the long coherence length, the spin-polarized electron beam can enhance the antibunching effect.« less

Apertureless near-field/far-field CW two-photon microscope for biological and material imaging and spectroscopic applications.

PubMed

Nowak, Derek B; Lawrence, A J; Sánchez, Erik J

2010-12-10

We present the development of a versatile spectroscopic imaging tool to allow for imaging with single-molecule sensitivity and high spatial resolution. The microscope allows for near-field and subdiffraction-limited far-field imaging by integrating a shear-force microscope on top of a custom inverted microscope design. The instrument has the ability to image in ambient conditions with optical resolutions on the order of tens of nanometers in the near field. A single low-cost computer controls the microscope with a field programmable gate array data acquisition card. High spatial resolution imaging is achieved with an inexpensive CW multiphoton excitation source, using an apertureless probe and simplified optical pathways. The high-resolution, combined with high collection efficiency and single-molecule sensitive optical capabilities of the microscope, are demonstrated with a low-cost CW laser source as well as a mode-locked laser source.

Early quantitative method for measuring germination in non-green spores of Dryopteris paleacea using an epifluorescence-microscope technique

NASA Technical Reports Server (NTRS)

Scheuerlein, R.; Wayne, R.; Roux, S. J.

1988-01-01

A method is described to determine germination by blue-light excited red fluorescence in the positively photoblastic spores of Dryopteris paleacea Sw. This fluorescence is due to chlorophyll as evidenced from 1) a fluorescence-emission spectrum in vivo, where a bright fluorescence around 675 nm is obtained only in red light (R)-irradiated spores and 2) in vitro measurements with acetone extracts prepared from homogenized spores. Significant amounts of chlorophyll can be found only in R-treated spores; this chlorophyll exhibits an emission band around 668 nm, when irradiated with 430 nm light at 21 degrees C. Compared to other criteria for germination, such as swelling of the cell, coat splitting, greening, and rhizoid formation, which require longer periods after induction for their expression, chlorophyll fluorescence can be used to quantify germination after two days. This result is confirmed by fluence-response curves for R-induced spore germination; the same relationship between applied R and germination is obtained by the evaluation with the epifluorescence method 2 days after the light treatment as compared with the evaluation with bright-field microscopy 5 days after the inducing R. Using this technique we show for the first time that Ca2+ contributes to the signal-transduction chain in phytochrome-mediated chlorophyll synthesis in spores of Dryopteris paleacea.

Tempo-spatially resolved scattering correlation spectroscopy under dark-field illumination and its application to investigate dynamic behaviors of gold nanoparticles in live cells.

PubMed

Liu, Heng; Dong, Chaoqing; Ren, Jicun

2014-02-19

In this study, a new tempo-spatially resolved fluctuation spectroscopy under dark-field illumination is described, named dark-field illumination-based scattering correlation spectroscopy (DFSCS). DFSCS is a single-particle method, whose principle is similar to that of fluorescence correlation spectroscopy (FCS). DFSCS correlates the fluctuations of the scattered light from single nanoparticle under dark-field illumination. We developed a theoretical model for translational diffusion of nanoparticles in DFSCS system. The results of computer simulations documented that this model was able to well describe the diffusion behaviors of nanoparticles in uniformly illuminated field. The experimental setup of DFSCS was achieved by introducing a dark-field condenser to the frequently used bright-field microscope and an electron multiplying charge-coupled device (EMCCD) as the array detector. In the optimal condition, a stack of 500 000 frames were collected simultaneously on 64 detection channels for a single measurement with acquisition rate of 0.5 ms per frame. We systematically investigated the effect of certain factors such as particle concentration, viscosity of the solution, and heterogeneity of gold nanoparticles (GNPs) samples on DFSCS measurements. The experiment data confirmed theoretical model proposed. Furthermore, this new method was successfully used for investigating dynamic behaviors of GNPs in live cells. Our preliminary results demonstrate that DFSCS is a practical and affordable tool for ordinary laboratories to investigate the dynamic information of nanoparticles in vitro as well as in vivo.

High-power broad-area diode lasers optimized for fiber laser pumping

NASA Astrophysics Data System (ADS)

Gilly, J.; Friedmann, P.; Kissel, H.; Biesenbach, J.; Kelemen, M. T.

2012-03-01

In diode laser applications for fibre laser pumping and materials processing high brightness becomes more and more important. At the moment fibre coupled modules benefit from continuous improvement of Broad-Area (BA) lasers on the chip level regarding output power, efficiency and far-field characteristics. To achieve high brightness not only the output power must be increased, but also the far field angles have to be maintained or even decreased because brightness is proportional to output power divided by beam quality. Typically fast axis far fields show mostly a current independent behaviour, for broad-area lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness. These limitations can be overcomed by carefully optimizing epitaxy-design and processing and also thermal management of the mounted device. The easiest way to achieve a good thermal management of BA-Lasers is to increase the resonator length while simultaneously decreasing internal losses of the epitaxy structure. To fulfill these issues, we have realized MBE grown InGaAs/AlGaAs broad-area with resonator lengths between 4mm and 6mm emitting at 976nm. To evaluate the brightness of these broad-area lasers single emitters have been mounted p-side down. Near- and far-fields have been carefully investigated. For a 4mm long broad-area laser with around 100μm emission width a beam parameter product of less than 3.5 mm x mrad has been achieved at 10W with a slope efficiency of more than 1.1W/A and a maximum wall-plug efficiency of more than 67%. For a device with 6mm resonator length we have reached a BPP of less than 3.5mm x mrad at 14W in slow axis direction which results in a brightness around 130MW/cm2 sr, which is to our knowledge the highest brightness reported so far for BA-lasers.

Drilling of optical glass with electroplated diamond tools

NASA Astrophysics Data System (ADS)

Wang, A. J.; Luan, C. G.; Yu, A. B.

2010-10-01

K9 optical glass drilling experiments were carried out. Bright nickel electroplated diamond tools with small slots and under heat treatment in different temperature were fabricated. Scan electro microscope was applied to analyze the wear of electroplated diamond tool. The material removal rate and grinding ratio were calculated. Machining quality was observed. Bond coating hardness was measured. The experimental results show that coolant is needed for the drilling processes of optical glasses. Heat treatment temperature of diamond tool has influence on wearability of diamond tool and grinding ratio. There were two wear types of electroplated diamond tool, diamond grit wear and bond wear. With the machining processes, wear of diamond grits included fracture, blunt and pull-out, and electroplated bond was gradually worn out. High material removal rates could be obtained by using diamond tool with suitable slot numbers. Bright nickel coating bond presents smallest grains and has better mechanical properties. Bright nickel electroplated diamond tool with slot structure and heat treatment under 200°C was suitable for optical glass drilling.

Three-dimensional bright-field scanning transmission electron microscopy elucidate novel nanostructure in microbial biofilms.

PubMed

Hickey, William J; Shetty, Ameesha R; Massey, Randall J; Toso, Daniel B; Austin, Jotham

2017-01-01

Bacterial biofilms play key roles in environmental and biomedical processes, and understanding their activities requires comprehension of their nanoarchitectural characteristics. Electron microscopy (EM) is an essential tool for nanostructural analysis, but conventional EM methods are limited in that they either provide topographical information alone, or are suitable for imaging only relatively thin (<300 nm) sample volumes. For biofilm investigations, these are significant restrictions. Understanding structural relations between cells requires imaging of a sample volume sufficiently large to encompass multiple cells and the capture of both external and internal details of cell structure. An emerging EM technique with such capabilities is bright-field scanning transmission electron microscopy (BF-STEM) and in the present report BF-STEM was coupled with tomography to elucidate nanostructure in biofilms formed by the polycyclic aromatic hydrocarbon-degrading soil bacterium, Delftia acidovorans Cs1-4. Dual-axis BF-STEM enabled high-resolution 3-D tomographic recontructions (6-10 nm) visualization of thick (1250 and 1500 nm) sections. The 3-D data revealed that novel extracellular structures, termed nanopods, were polymorphic and formed complex networks within cell clusters. BF-STEM tomography enabled visualization of conduits formed by nanopods that could enable intercellular movement of outer membrane vesicles, and thereby enable direct communication between cells. This report is the first to document application of dual-axis BF-STEM tomography to obtain high-resolution 3-D images of novel nanostructures in bacterial biofilms. Future work with dual-axis BF-STEM tomography combined with correlative light electron microscopy may provide deeper insights into physiological functions associated with nanopods as well as other nanostructures. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Oligonucleotide PIK3CA/Chromosome 3 Dual in Situ Hybridization Automated Assay with Improved Signals, One-Hour Hybridization, and No Use of Blocking DNA.

PubMed

Zhang, Wenjun; Hubbard, Antony; Baca-Parkinson, Leslie; Stanislaw, Stacey; Vladich, Frank; Robida, Mark D; Grille, James G; Maxwell, Daniel; Tsao, Tsu-Shuen; Carroll, William; Gardner, Tracie; Clements, June; Singh, Shalini; Tang, Lei

2015-09-01

The PIK3CA gene at chromosome 3q26.32 was found to be amplified in up to 45% of patients with squamous cell carcinoma of the lung. The strong correlation between PIK3CA amplification and increased phosphatidylinositol 3-kinase (PI3K) pathway activities suggested that PIK3CA gene copy number is a potential predictive biomarker for PI3K inhibitors. Currently, all microscopic assessments of PIK3CA and chromosome 3 (CHR3) copy numbers use fluorescence in situ hybridization. PIK3CA probes are derived from bacterial artificial chromosomes whereas CHR3 probes are derived mainly from the plasmid pHS05. These manual fluorescence in situ hybridization assays mandate 12- to 18-hour hybridization and use of blocking DNA from human sources. Moreover, fluorescence in situ hybridization studies provide limited morphologic assessment and suffer from signal decay. We developed an oligonucleotide-based bright-field in situ hybridization assay that overcomes these shortcomings. This assay requires only a 1-hour hybridization with no need for blocking DNA followed by indirect chromogenic detection. Oligonucleotide probes produced discrete and uniform CHR3 stains superior to those from the pHS05 plasmid. This assay achieved successful staining in 100% of the 195 lung squamous cell carcinoma resections and in 94% of the 33 fine-needle aspirates. This robust automated bright-field dual in situ hybridization assay for the simultaneous detection of PIK3CA and CHR3 centromere provides a potential clinical diagnostic method to assess PIK3CA gene abnormality in lung tumors. Copyright © 2015 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

Neutral-Line Magnetic Shear and Enhanced Coronal Heating in Solar Active Regions

NASA Technical Reports Server (NTRS)

Falconer, D. A.; Moore, R. L.; Porter, J. G.; Gary, G. A.; Shimizu, T.

1997-01-01

By examining the magnetic structure at sites in the bright coronal interiors of active regions that are not flaring but exhibit persistent strong coronal heating, we establish some new characteristics of the magnetic origins of this heating. We have examined the magnetic structure of these sites in five active regions, each of which was well observed by both the Yohkoh SXT and the Marshall Space Flight Center Vector Magnetograph and showed strong shear in its magnetic field along part of at least one neutral line (polarity inversion). Thus, we can assess whether this form of nonpotential field structure in active regions is a characteristic of the enhanced coronal heating and vice versa. From 27 orbits' worth of Yohkoh SXT images of the five active regions, we have obtained a sample of 94 persistently bright coronal features (bright in all images from a given orbit), 40 long (greater than or approximately equals 20,000 km) neutral-line segments having strong magnetic shear throughout (shear angle greater than 45 deg), and 39 long neutral-line segments having weak magnetic shear throughout (shear angle less than 45 deg). From this sample, we find that: (1) all of our persistently bright coronal features are rooted in magnetic fields that are stronger than 150 G; (2) nearly all (95%) of these enhanced coronal features are rooted near neutral lines (closer than 10,000 km); (3) a great majority (80%) of the bright features are rooted near strong-shear portions of neutral lines; (4) a great majority (85%) of long strong-shear segments of neutral lines have persistently bright coronal features rooted near them; (5) a large minority (40%) of long weak-shear segments of neutral lines have persistently bright coronal features rooted near them; and (6) the brightness of a persistently bright Coronal feature often changes greatly over a few hours. From these results, we conclude that most persistent enhanced heating of coronal loops in active regions: (1) requires the presence of a polarity inversion in the magnetic field near at least one of the loop footpoints; (2) is greatly aided by the presence of strong shear in the core magnetic field along that neutral line; and (3) is controlled by some variable process that acts in this magnetic environment. We infer that this variable process is low-lying reconnection accompanying flux cancellation.

Hα Surges Initiated by Newly-emerging Satellite Magnetic Fields

NASA Astrophysics Data System (ADS)

Wang, Jun-feng; Zhou, Tuan-hui; Ji, Hai-sheng

2014-01-01

On July 22, 2011 and in the active region NOAA 11259 there ap- peared the event of the ejection of solar atmospheric Hα surges. According to the full-disc Hα observations of the Big Bear Solar Observatory in United States, three consecutive surges at one and the same place in the north of the main spot of the active region were discovered. The trajectories of these three surges exhib- ited the figure of straight lines, and their integral configuration is like an inverted Eiffel Tower. The first two surges are quite similar, and in each of them there appeared two bright points in the northern part of the main spot. After several minutes, the surges appeared in the midst of bright points. When the bright- ness of the bright points attained the maximum value, the surges spouted out from the midst of bright points. And after reaching the maximum altitude, they quickly vanished. Before the ejection of the third surge took place, no bright points appeared. Besides, its maximal altitude is merely one half of that of the first two surges. Via a comparison with the SDO/HMI (Solar Dynamics Obser- vatory/Helioseismic and Magnetic Imager) data of radial magnetic fields, it is found that in more than one hour before the appearance of the first surge there emerged bipolar magnetic fields in the region of ejection. Besides, in several min- utes before the ejection of each Hα surge the magnetic fluxes of positive polarity diminished. Via our analysis it is found that there appeared reconnections be- tween the newly emerging satellite magnetic fields and the preexisting magnetic fields in the spot, and this caused the continuous ejections of Hα surges.

Evaluations of carbon nanotube field emitters for electron microscopy

NASA Astrophysics Data System (ADS)

Nakahara, Hitoshi; Kusano, Yoshikazu; Kono, Takumi; Saito, Yahachi

2009-11-01

Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I- V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6×109 A/m 2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum in Microwaves

NASA Technical Reports Server (NTRS)

Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D.

2011-01-01

Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radio-heliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approx.250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes.

Investigation of the moving structures in a coronal bright point

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

Ning, Zongjun; Guo, Yang, E-mail: ningzongjun@pmo.ac.cn

2014-10-10

We have explored the moving structures in a coronal bright point (CBP) observed by the Solar Dynamic Observatory Atmospheric Imaging Assembly (AIA) on 2011 March 5. This CBP event has a lifetime of ∼20 minutes and is bright with a curved shape along a magnetic loop connecting a pair of negative and positive fields. AIA imaging observations show that a lot of bright structures are moving intermittently along the loop legs toward the two footpoints from the CBP brightness core. Such moving bright structures are clearly seen at AIA 304 Å. In order to analyze their features, the CBP ismore » cut along the motion direction with a curved slit which is wide enough to cover the bulk of the CBP. After integrating the flux along the slit width, we get the spacetime slices at nine AIA wavelengths. The oblique streaks starting from the edge of the CBP brightness core are identified as moving bright structures, especially on the derivative images of the brightness spacetime slices. They seem to originate from the same position near the loop top. We find that these oblique streaks are bi-directional, simultaneous, symmetrical, and periodic. The average speed is about 380 km s{sup –1}, and the period is typically between 80 and 100 s. Nonlinear force-free field extrapolation shows the possibility that magnetic reconnection takes place during the CBP, and our findings indicate that these moving bright structures could be the observational outflows after magnetic reconnection in the CBP.« less

Intrinsic Brightness Temperatures of AGN Jets

NASA Astrophysics Data System (ADS)

Homan, D. C.; Kovalev, Y. Y.; Lister, M. L.; Ros, E.; Kellermann, K. I.; Cohen, M. H.; Vermeulen, R. C.; Zensus, J. A.; Kadler, M.

2006-05-01

We present a new method for studying the intrinsic brightness temperatures of the parsec-scale jet cores of active galactic nuclei (AGNs). Our method uses observed superluminal motions and observed brightness temperatures for a large sample of AGNs to constrain the characteristic intrinsic brightness temperature of the sample as a whole. To study changes in intrinsic brightness temperature, we assume that the Doppler factors of individual jets are constant in time, as justified by their relatively small changes in observed flux density. We find that in their median-low brightness temperature state, the sources in our sample have a narrow range of intrinsic brightness temperatures centered on a characteristic temperature, Tint~=3×1010 K, which is close to the value expected for equipartition, when the energy in the radiating particles equals the energy stored in the magnetic fields. However, in their maximum brightness state, we find that sources in our sample have a characteristic intrinsic brightness temperature greater than 2×1011 K, which is well in excess of the equipartition temperature. In this state, we estimate that the energy in radiating particles exceeds the energy in the magnetic field by a factor of ~105. We suggest that the excess of particle energy when sources are in their maximum brightness state is due to injection or acceleration of particles at the base of the jet. Our results suggest that the common method of estimating jet Doppler factors by using a single measurement of observed brightness temperature, the assumption of equipartition, or both may lead to large scatter or systematic errors in the derived values.

Relationship of magnetic field strength and brightness of fine-structure elements in the solar temperature minimum region

NASA Technical Reports Server (NTRS)

Cook, J. W.; Ewing, J. A.

1990-01-01

A quantitative relationship was determined between magnetic field strength (or magnetic flux) from photospheric magnetograph observations and the brightness temperature of solar fine-structure elements observed at 1600 A, where the predominant flux source is continuum emission from the solar temperature minimum region. A Kitt Peak magnetogram and spectroheliograph observations at 1600 A taken during a sounding rocket flight of the High Resolution Telescope and Spectrograph from December 11, 1987 were used. The statistical distributions of brightness temperature in the quiet sun at 1600 A, and absolute value of magnetic field strength in the same area were determined from these observations. Using a technique which obtains the best-fit relationship of a given functional form between these two histogram distributions, a quantitative relationship was determined between absolute value of magnetic field strength B and brightness temperature which is essentially linear from 10 to 150 G. An interpretation is suggested, in which a basal heating occurs generally, while brighter elements are produced in magnetic regions with temperature enhancements proportional to B.

Microstructure study of a severely plastically deformed Mg-Zn-Y alloy by application of low angle annular dark field diffraction contrast imaging.

PubMed

Basha, Dudekula Althaf; Rosalie, Julian M; Somekawa, Hidetoshi; Miyawaki, Takashi; Singh, Alok; Tsuchiya, Koichi

2016-01-01

Microstructural investigation of extremely strained samples, such as severely plastically deformed (SPD) materials, by using conventional transmission electron microscopy techniques is very challenging due to strong image contrast resulting from the high defect density. In this study, low angle annular dark field (LAADF) imaging mode of scanning transmission electron microscope (STEM) has been applied to study the microstructure of a Mg-3Zn-0.5Y (at%) alloy processed by high pressure torsion (HPT). LAADF imaging advantages for observation of twinning, grain fragmentation, nucleation of recrystallized grains and precipitation on second phase particles in the alloy processed by HPT are highlighted. By using STEM-LAADF imaging with a range of incident angles, various microstructural features have been imaged, such as nanoscale subgrain structure and recrystallization nucleation even from the thicker region of the highly strained matrix. It is shown that nucleation of recrystallized grains starts at a strain level of revolution [Formula: see text] (earlier than detected by conventional bright field imaging). Occurrence of recrystallization of grains by nucleating heterogeneously on quasicrystalline particles is also confirmed. Minimizing all strain effects by LAADF imaging facilitated grain size measurement of [Formula: see text] nm in fully recrystallized HPT specimen after [Formula: see text].

Microscopy using source and detector arrays

NASA Astrophysics Data System (ADS)

Sheppard, Colin J. R.; Castello, Marco; Vicidomini, Giuseppe; Duocastella, Martí; Diaspro, Alberto

2016-03-01

There are basically two types of microscope, which we call conventional and scanning. The former type is a full-field imaging system. In the latter type, the object is illuminated with a probe beam, and a signal detected. We can generalize the probe to a patterned illumination. Similarly we can generalize the detection to a patterned detection. Combining these we get a range of different modalities: confocal microscopy, structured illumination (with full-field imaging), spinning disk (with multiple illumination points), and so on. The combination allows the spatial frequency bandwidth of the system to be doubled. In general we can record a four dimensional (4D) image of a 2D object (or a 6D image from a 3D object, using an acoustic tuneable lens). The optimum way to directly reconstruct the resulting image is by image scanning microscopy (ISM). But the 4D image is highly redundant, so deconvolution-based approaches are also relevant. ISM can be performed in fluorescence, bright field or interference microscopy. Several different implementations have been described, with associated advantages and disadvantages. In two-photon microscopy, the illumination and detection point spread functions are very different. This is also the case when using pupil filters or when there is a large Stokes shift.

NEAR-IR IMAGING POLARIMETRY TOWARD A BRIGHT-RIMMED CLOUD: MAGNETIC FIELD IN SFO 74

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

Kusune, Takayoshi; Sugitani, Koji; Miao, Jingqi

2015-01-01

We have made near-infrared (JHK {sub s}) imaging polarimetry of a bright-rimmed cloud (SFO 74). The polarization vector maps clearly show that the magnetic field in the layer just behind the bright rim is running along the rim, quite different from its ambient magnetic field. The direction of the magnetic field just behind the tip rim is almost perpendicular to that of the incident UV radiation, and the magnetic field configuration appears to be symmetric as a whole with respect to the cloud symmetry axis. We estimated the column and number densities in the two regions (just inside and farmore » inside the tip rim) and then derived the magnetic field strength, applying the Chandrasekhar-Fermi method. The estimated magnetic field strength just inside the tip rim, ∼90 μG, is stronger than that far inside, ∼30 μG. This suggests that the magnetic field strength just inside the tip rim is enhanced by the UV-radiation-induced shock. The shock increases the density within the top layer around the tip and thus increases the strength of the magnetic field. The magnetic pressure seems to be comparable to the turbulent one just inside the tip rim, implying a significant contribution of the magnetic field to the total internal pressure. The mass-to-flux ratio was estimated to be close to the critical value just inside the tip rim. We speculate that the flat-topped bright rim of SFO 74 could be formed by the magnetic field effect.« less

Diode lasers optimized in brightness for fiber laser pumping

NASA Astrophysics Data System (ADS)

Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.

2018-02-01

In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.

Relative ordering between bright and dark excitons in single-walled carbon nanotubes.

PubMed

Zhou, Weihang; Nakamura, Daisuke; Liu, Huaping; Kataura, Hiromichi; Takeyama, Shojiro

2014-11-11

The ordering and relative energy splitting between bright and dark excitons are critical to the optical properties of single-walled carbon nanotubes (SWNTs), as they eventually determine the radiative and non-radiative recombination processes of generated carriers. In this work, we report systematic high-field magneto-optical study on the relative ordering between bright and dark excitons in SWNTs. We identified the relative energy position of the dark exciton unambiguously by brightening it in ultra-high magnetic field. The bright-dark excitonic ordering was found to depend not only on the tube structure, but also on the type of transitions. For the 1(st) sub-band transition, the bright exciton appears to be higher in energy than its dark counterpart for any chiral species and is robust against environmental effect. While for the 2(nd) sub-band, their relative ordering was found to be chirality-sensitive: the bright exciton can be either higher or lower than the dark one, depending on the specific nanotube structures. These findings provide new clues for engineering the optical and electronic properties of SWNTs.

Field ion microscopic studies of the CO oxidation on platinum: Bistability and oscillations

NASA Astrophysics Data System (ADS)

Gorodetskii, V.; Drachsel, W.; Ehsasi, M.; Block, J. H.

1994-05-01

The oscillating CO oxidation is investigated on a Pt-field emitter tip by using the field ion mode of surface imaging of Oad sites with O2 as imaging gas. Based on data of the titration reactions [V. Gorodetskii, W. Drachsel, and J. H. Block, J. Chem. Phys. 100, C. E. UPDATE (1994)], external control parameters for the regions of bistability and of self-sustained isothermal oscillations could be found. On a field emitter tip, oscillations can be generated in a rather large parameter space. The anticlockwise hysteresis of O+2 ion currents in temperature cycles occurs in agreement with results on single crystal planes. Unexpected regular oscillation sequences could occasionally be obtained on the small surface areas of a field emitter tip and measured as function of the CO partial pressure and of the temperature. Different stages within oscillating cycles were documented by field ion images. Oscillations of total ion currents are correlated with variations in the spatial brightness of field ion images. In the manifold of single crystal planes of a field emitter {331} planes around the {011} regions are starting points for oscillations which mainly proceed along [100] vicinals. This excludes the {111} regions from autonomous oscillations. With slightly increased CO partial pressures fast local oscillations at a few hundred surface sites of the Pt(001) plane display short-living CO islands of 40 to 50 Å diameter. Temporal oscillations of the total O+2 ion current are mainly caused by surface plane specific spatial oscillations. The synchronization is achieved by diffusion reaction fronts rather than by gas phase synchronization.

WE-D-BRF-01: FEATURED PRESENTATION - Investigating Particle Track Structures Using Fluorescent Nuclear Track Detectors and Monte Carlo Simulations

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

Dowdell, S; Paganetti, H; Schuemann, J

Purpose: To report on the efforts funded by the AAPM seed funding grant to develop the basis for fluorescent nuclear track detector (FNTD) based radiobiological experiments in combination with dedicated Monte Carlo simulations (MCS) on the nanometer scale. Methods: Two confocal microscopes were utilized in this study. Two FNTD samples were used to find the optimal microscope settings, one FNTD irradiated with 11.1 MeV/u Gold ions and one irradiated with 428.77 MeV/u Carbon ions. The first sample provided a brightly luminescent central track while the latter is used to test the capabilities to observe secondary electrons. MCS were performed usingmore » TOPAS beta9 version, layered on top of Geant4.9.6p02. Two sets of simulations were performed, one with the Geant4-DNA physics list and approximating the FNTDs by water, a second set using the Penelope physics list in a water-approximated FNTD and a aluminum-oxide FNTD. Results: Within the first half of the funding period, we have successfully established readout capabilities of FNTDs at our institute. Due to technical limitations, our microscope setup is significantly different from the approach implemented at the DKFZ, Germany. However, we can clearly reconstruct Carbon tracks in 3D with electron track resolution of 200 nm. A second microscope with superior readout capabilities will be tested in the second half of the funding period, we expect an improvement in signal to background ratio with the same the resolution.We have successfully simulated tracks in FNTDs. The more accurate Geant4-DNA track simulations can be used to reconstruct the track energy from the size and brightness of the observed tracks. Conclusion: We have achieved the goals set in the seed funding proposal: the setup of FNTD readout and simulation capabilities. We will work on improving the readout resolution to validate our MCS track structures down to the nanometer scales.« less

Randomized placebo-controlled field study of the effects of bright light and melatonin in adaptation to night work.

PubMed

Bjorvatn, Bjørn; Stangenes, Kristine; Oyane, Nicolas; Forberg, Knut; Lowden, Arne; Holsten, Fred; Akerstedt, Torbjørn

2007-06-01

This study evaluated the effects of bright light and melatonin on adaptation to night work on an oil rig in the North Sea. Seventeen persons working a schedule of 2 weeks on a 12-hour shift, with the first week on night shift and the second week on day shift (ie, the swing shift schedule) participated. In a randomized controlled crossover design, the shift workers received a placebo, melatonin (3 mg, 1 hour before bedtime), or bright light (30-minute exposure, individually scheduled) during the first 4 days on the night shift and during the first 4 days on the day shift. Subjective and objective measures of sleepiness (Karolinska Sleepiness Scale and a simple serial reaction-time test) and sleep (diary and actigraphy) were recorded. Subjective measures indicated that melatonin modestly reduced sleepiness at work during the day shift and increased sleep by 15-20 minutes per day. Bright light gave values in between those of melatonin and the placebo, but with few significant results. According to the objective measures, bright light improved sleep to a minor degree during the night shift. Hardly any side-effects were reported. Melatonin and bright light modestly improved sleep and sleepiness in this field study. In well-controlled simulated nightwork studies, both melatonin and bright light are more effective in alleviating sleepiness and sleep problems. The less effect in this field study may be due to competing or conflicting factors present in real life or to an inoptimal timing and duration of the treatments.

Healing properties of implants inserted concomitantly with anorganic bovine bone. A histomorphometric human study.

PubMed

Menicucci, G; Mussano, F; Schierano, G; Rizzati, A; Aimetti, M; Gassino, G; Traini, T; Carossa, S

2013-03-01

The present prospective, randomized, double-blind study evaluated the bone-forming process around implants inserted simultaneously with anorganic bovine bone (ABB) in sinus grafting. A total of 18 threaded mini-implants with Osseotite (O) and Nanotite (N) surfaces were placed in seven patients (nine sites). After 12 months, the implants were retrieved and processed for histological analysis. A total of 18 cutting and grinding sections were investigated with bright-field light microscopy, circularly polarized light microscopy (CPLM), confocal scanning laser microscope (CSLM), and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). The bone-to-implant contact rate in native crestal bone was 62.6 ± 0.4% for N implants and 54.3 ± 0.5% for the O implants (p = 0.001). The collagen fibre density, as assessed by CPLM, was 79.8 ± 6.0 nm for the N group and 74.6 ± 4.6 nm for the O group (p < 0.05). Line scan EDS starting from ABB to newly formed bone showed a decrease in calcium content and an increase of carbon while phosphorus content was constant. While the N surface improved the peri-implant endosseous healing properties in the native bone, when compared to the O surface, it did not improve the healing properties in the bone-graft area. © 2013 Australian Dental Association.

Kirkpatrick-Baez microscope for hard X-ray imaging of fast ignition experiments.

PubMed

Friesen, H; Tiedje, H F; Hey, D S; Mo, M Z; Beaudry, A; Fedosejevs, R; Tsui, Y Y; Mackinnon, A; McLean, H S; Patel, P K

2013-02-01

A Kirkpatrick-Baez X-ray microscope has been developed for use on the Titan laser facility at the Lawrence Livermore National Laboratory in Fast Ignition experiments. It was developed as a broadband alternative to narrow band Bragg crystal imagers for imaging Kα emission from tracer layers. A re-entrant design is employed which allows for alignment from outside the chamber. The mirrors are coated with Pt and operate at a grazing incident angle of 0.5° providing higher resolution than an equal brightness pinhole and sufficient bandwidth to image thermally shifted characteristic Kα emission from heated Cu tracer layers in Fast Ignition experiments. The superpolished substrates (<1 Å rms roughness) had a final visible wavelength roughness of 1.7 Å after coating, and exhibited a reflectivity corresponding to an X-ray wavelength roughness of 7 ± 1 Å. A unique feature of this design is that during experiments, the unfiltered direct signal along with the one-dimensional reflections are retained on the detector in order to enable a live indication of alignment and incident angle. The broad spectral window from 4 to 9 keV enables simultaneous observation of emission from several spectral regions of interest, which has been demonstrated to be particularly useful for cone-wire targets. An experimentally measured resolution of 15 μm has been obtained at the center of the field of view.

Cryo-image Analysis of Tumor Cell Migration, Invasion, and Dispersal in a Mouse Xenograft Model of Human Glioblastoma Multiforme

PubMed Central

Qutaish, Mohammed Q.; Sullivant, Kristin E.; Burden-Gulley, Susan M.; Lu, Hong; Roy, Debashish; Wang, Jing; Basilion, James P.; Brady-Kalnay, Susann M.; Wilson, David L.

2012-01-01

Purpose The goals of this study were to create cryo-imaging methods to quantify characteristics (size, dispersal, and blood vessel density) of mouse orthotopic models of glioblastoma multiforme (GBM) and to enable studies of tumor biology, targeted imaging agents, and theranostic nanoparticles. Procedures Green fluorescent protein-labeled, human glioma LN-229 cells were implanted into mouse brain. At 20–38 days, cryo-imaging gave whole brain, 4-GB, 3D microscopic images of bright field anatomy, including vasculature, and fluorescent tumor. Image analysis/visualization methods were developed. Results Vessel visualization and segmentation methods successfully enabled analyses. The main tumor mass volume, the number of dispersed clusters, the number of cells/cluster, and the percent dispersed volume all increase with age of the tumor. Histograms of dispersal distance give a mean and median of 63 and 56 μm, respectively, averaged over all brains. Dispersal distance tends to increase with age of the tumors. Dispersal tends to occur along blood vessels. Blood vessel density did not appear to increase in and around the tumor with this cell line. Conclusion Cryo-imaging and software allow, for the first time, 3D, whole brain, microscopic characterization of a tumor from a particular cell line. LN-229 exhibits considerable dispersal along blood vessels, a characteristic of human tumors that limits treatment success. PMID:22125093

The early study on the inspection of tongue of the traditional Chinese medicine using optical coherence tomography

NASA Astrophysics Data System (ADS)

Zhong, Hui-Qing; Zeng, Chang-Chun; Guo, Zhou-Yi; He, Yong-Hong; Wang, Rui-Kang; Liu, Song-Hao

2007-05-01

Inspection of tongue is an age-old technique used by Traditional Chinese Medicine (TCM) practitioners to determine a patient's health status. Because tongue examination is a subjective and inaccurate diagnostic method, a scientific tool which can provide objective and accurate information is needed to assist the TCM practitioners in their practice. The purpose of the study was to examine the feasibility of developing a glossoscopy from an optical coherence tomography (OCT) imaging system. In the present study, an OCT system was used to examine the tongue of the rat. After examination, the tongue was surgically removed, sectioned by a microtome and put on a glass slide for histological examination. The slides were examined under a bright-field microscope. Results of the OCT imaging studies showed that the OCT system was capable of showing the images of three distinct regions of the tongue: the tongue coating layers, the interface between the tongue coating and the tongue body, and the tongue body. It was also possible to assign an index number to each of the coating layers. When the tongue tissue was examined under a microscope, three separate regions of the tongue also were visible. Results of this pilot study shows that the OCT potentially can be developed into a glossoscopy for clinical application in TCM practice.

One-step synthesis of hybrid inorganic-organic nanocomposite coatings by novel laser adaptive ablation deposition technique

NASA Astrophysics Data System (ADS)

Serbezov, Valery; Sotirov, Sotir

2013-03-01

A novel approach for one-step synthesis of hybrid inorganic-organic nanocomposite coatings by new modification of Pulsed Laser Deposition technology called Laser Adaptive Ablation Deposition (LAAD) is presented. Hybrid nanocomposite coatings including Mg- Rapamycin and Mg- Desoximetasone were produced by UV TEA N2 laser under low vacuum (0.1 Pa) and room temperature onto substrates from SS 316L, KCl and NaCl. The laser fluence for Mg alloy was 1, 8 J/cm2 and for Desoximetasone 0,176 J/cm2 and for Rapamycin 0,118 J/cm2 were respectively. The threedimensional two-segmented single target was used to adapt the interaction of focused laser beam with inorganic and organic material. Magnesium alloy nanoparticles with sizes from 50 nm to 250 nm were obtained in organic matrices. The morphology of nanocomposites films were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Fourier Transform Infrared (FTIR) spectroscopy measurements were applied in order to study the functional properties of organic component before and after the LAAD process. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of Mg alloy presence in hybrid nanocomposites coatings. The precise control of process parameters and particularly of the laser fluence adjustment enables transfer on materials with different physical chemical properties and one-step synthesis of complex inorganic- organic nanocomposites coatings.

Properties of an H I-selected galaxy sample

NASA Technical Reports Server (NTRS)

Szomoru, Arpad; Guhathakurta, Puragra; Van Gorkom, Jacqueline H.; Knapen, Johan H.; Weinberg, David H.; Fruchter, Andrew S.

1994-01-01

We analyze the properties of a sample of galaxies identified in a 21cm, H I-line survey of selected areas in the Perseus-Pisces supercluster and its foreground void. Twelve fields were observed in the supercluster, five of them (target fields) centered on optically bright galaxies, and the other seven (blank fields) selected to contain no bright galaxies within 45 min. of their centers. We detected nine previously uncatalogued, gas-rich galaxies, six of them in the target fields. We also detected H I from seven previously catalogued galaxies in these fields. Observations in the void covered the same volume as the 12 supercluster fields at the same H I-mass sensitivity, but no objects were detected. Combining out H I data with optical broadband and H alpha imaging, we conclude that the properties of H I-selected galaxies do not differ substantially from those of late-type galaxies found in optical surveys. In particular, the galaxies in our sample do not appear to be unusually faint for their H I mass, or for their circular velocity. We find tentative evidence for a connection between optical surface brightness and degree of isolation, in the sense that low surface brightness galaxies tend to be more isolated. The previously catalogued, optically bright galaxies in our survey volume dominate the total H I mass density and cross section; the uncatalogued galaxies contribute only approximately 19 percent of the mass and approximately 12 percent of the cross section. Thus, existing estimates of the density and cross section of neutral hydrogen, most of which are based on optically selected galaxy samples, are probably accurate. Such estimates can be used to compare the nearby universe to the high-redshift universe probed by quasar absorption lines.

Remote sensing of soil moisture content over bare fields at 1.4 GHz frequency

NASA Technical Reports Server (NTRS)

Wang, J. R.; Choudhury, B. J.

1980-01-01

A simple method of estimating moisture content (W) of a bare soil from the observed brightness temperature (T sub B) at 1.4 GHz is discussed. The method is based on a radiative transfer model calculation, which has been successfully used in the past to account for many observational results, with some modifications to take into account the effect of surface roughness. Besides the measured T sub B's, the three additional inputs required by the method are the effective soil thermodynamic temperature, the precise relation between W and the smooth field brightness temperature T sub B and a parameter specifying the surface roughness characteristics. The soil effective temperature can be readily measured and the procedures of estimating surface roughness parameter and obtaining the relation between W and smooth field brightness temperature are discussed in detail. Dual polarized radiometric measurements at an off-nadir incident angle are sufficient to estimate both surface roughness parameter and W, provided that the relation between W and smooth field brightness temperature at the same angle is known. The method of W estimate is demonstrated with two sets of experimental data, one from a controlled field experiment by a mobile tower and the other, from aircraft overflight. The results from both data sets are encouraging when the estimated W's are compared with the acquired ground truth of W's in the top 2 cm layer. An offset between the estimated and the measured W's exists in the results of the analyses, but that can be accounted for by the presently poor knowledge of the relationship between W and smooth field brightness temperature for various types of soils. An approach to quantify this relationship for different soils and thus improve the method of W estimate is suggested.

Rapid microscopy measurement of very large spectral images.

PubMed

Lindner, Moshe; Shotan, Zav; Garini, Yuval

2016-05-02

The spectral content of a sample provides important information that cannot be detected by the human eye or by using an ordinary RGB camera. The spectrum is typically a fingerprint of the chemical compound, its environmental conditions, phase and geometry. Thus measuring the spectrum at each point of a sample is important for a large range of applications from art preservation through forensics to pathological analysis of a tissue section. To date, however, there is no system that can measure the spectral image of a large sample in a reasonable time. Here we present a novel method for scanning very large spectral images of microscopy samples even if they cannot be viewed in a single field of view of the camera. The system is based on capturing information while the sample is being scanned continuously 'on the fly'. Spectral separation implements Fourier spectroscopy by using an interferometer mounted along the optical axis. High spectral resolution of ~5 nm at 500 nm could be achieved with a diffraction-limited spatial resolution. The acquisition time is fairly high and takes 6-8 minutes for a sample size of 10mm x 10mm measured under a bright-field microscope using a 20X magnification.

Wake-field and space charge effects on high brightness beams calculations and measured results for the laser driven photoelectrons at BNL-ATF

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

Parsa, Z.

1993-05-01

We discuss the formalism used to study the effects of the interactions between the highly charged particles and the fields in the accelerating structure, including space charge and wake fields. Some of our calculations and numerical simulation results obtained for the Brookhaven National Laboratory (BNL) high-brightness photoelectron beam at the Accelerator Test Facility (ATF) and the measured data at ATF are also included.

Brightness temperature - obtaining the physical properties of a non-equipartition plasma

NASA Astrophysics Data System (ADS)

Nokhrina, E. E.

2017-06-01

The limit on the intrinsic brightness temperature, attributed to `Compton catastrophe', has been established being 1012 K. Somewhat lower limit of the order of 1011.5 K is implied if we assume that the radiating plasma is in equipartition with the magnetic field - the idea that explained why the observed cores of active galactic nuclei (AGNs) sustained the limit lower than the `Compton catastrophe'. Recent observations with unprecedented high resolution by the RadioAstron have revealed systematic exceed in the observed brightness temperature. We propose means of estimating the degree of the non-equipartition regime in AGN cores. Coupled with the core-shift measurements, the method allows us to independently estimate the magnetic field strength and the particle number density at the core. We show that the ratio of magnetic energy to radiating plasma energy is of the order of 10-5, which means the flow in the core is dominated by the particle energy. We show that the magnetic field obtained by the brightness temperature measurements may be underestimated. We propose for the relativistic jets with small viewing angles the non-uniform magnetohydrodynamic model and obtain the expression for the magnetic field amplitude about two orders higher than that for the uniform model. These magnetic field amplitudes are consistent with the limiting magnetic field suggested by the `magnetically arrested disc' model.

Microscopic observation of magnetic bacteria in the magnetic field of a rotating permanent magnet.

PubMed

Smid, Pieter; Shcherbakov, Valeriy; Petersen, Nikolai

2015-09-01

Magnetotactic bacteria are ubiquitous and can be found in both freshwater and marine environments. Due to intracellular chains of magnetic single domain particles, they behave like swimming compass needles. In external magnetic fields like the Earth's magnetic field, a torque is acting on the chain. This will cause the bacterium to be rotated and aligned with the external field. The swimming direction of magnetotactic bacteria can be controlled with external magnetic fields, which makes it convenient to study them under a light microscope. Usually, a special set of coils arranged around a light microscope is used to control the swimming magnetotactic bacteria. Here, we present a simple mechanical system with a permanent magnet, which produces a rotating magnetic field of nearly constant amplitude in the focal plane of a light microscope. The device is placed beside the light microscope and easily adaptable to almost any microscope and thus convenient for field experiments. To describe the trajectories qualitatively, a theoretical model of the trajectories is presented. This device can be used to control the swimming direction of magnetotactic bacteria and also for studying their magnetic and hydrodynamic properties.

Quantitative comparison of bright field and annular bright field imaging modes for characterization of oxygen octahedral tilts

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

Kim, Young-Min; Pennycook, Stephen J.; Borisevich, Albina Y.

Octahedral tilt behavior is increasingly recognized as an important contributing factor to the physical behavior of perovskite oxide materials and especially their interfaces, necessitating the development of high-resolution methods of tilt mapping. There are currently two major approaches for quantitative imaging of tilts in scanning transmission electron microscopy (STEM), bright field (BF) and annular bright field (ABF). In this study, we show that BF STEM can be reliably used for measurements of oxygen octahedral tilts. While optimal conditions for BF imaging are more restricted with respect to sample thickness and defocus, we find that BF imaging with an aberration-corrected microscopemore » with the accelerating voltage of 300 kV gives us the most accurate quantitative measurement of the oxygen column positions. Using the tilted perovskite structure of BiFeO 3 (BFO) as our test sample, we simulate BF and ABF images in a wide range of conditions, identifying the optimal imaging conditions for each mode. Finally, we show that unlike ABF imaging, BF imaging remains directly quantitatively interpretable for a wide range of the specimen mistilt, suggesting that it should be preferable to the ABF STEM imaging for quantitative structure determination.« less

Quantitative comparison of bright field and annular bright field imaging modes for characterization of oxygen octahedral tilts

DOE PAGES

Kim, Young-Min; Pennycook, Stephen J.; Borisevich, Albina Y.

2017-04-29

Octahedral tilt behavior is increasingly recognized as an important contributing factor to the physical behavior of perovskite oxide materials and especially their interfaces, necessitating the development of high-resolution methods of tilt mapping. There are currently two major approaches for quantitative imaging of tilts in scanning transmission electron microscopy (STEM), bright field (BF) and annular bright field (ABF). In this study, we show that BF STEM can be reliably used for measurements of oxygen octahedral tilts. While optimal conditions for BF imaging are more restricted with respect to sample thickness and defocus, we find that BF imaging with an aberration-corrected microscopemore » with the accelerating voltage of 300 kV gives us the most accurate quantitative measurement of the oxygen column positions. Using the tilted perovskite structure of BiFeO 3 (BFO) as our test sample, we simulate BF and ABF images in a wide range of conditions, identifying the optimal imaging conditions for each mode. Finally, we show that unlike ABF imaging, BF imaging remains directly quantitatively interpretable for a wide range of the specimen mistilt, suggesting that it should be preferable to the ABF STEM imaging for quantitative structure determination.« less

The algorithm stitching for medical imaging

NASA Astrophysics Data System (ADS)

Semenishchev, E.; Marchuk, V.; Voronin, V.; Pismenskova, M.; Tolstova, I.; Svirin, I.

2016-05-01

In this paper we propose a stitching algorithm of medical images into one. The algorithm is designed to stitching the medical x-ray imaging, biological particles in microscopic images, medical microscopic images and other. Such image can improve the diagnosis accuracy and quality for minimally invasive studies (e.g., laparoscopy, ophthalmology and other). The proposed algorithm is based on the following steps: the searching and selection areas with overlap boundaries; the keypoint and feature detection; the preliminary stitching images and transformation to reduce the visible distortion; the search a single unified borders in overlap area; brightness, contrast and white balance converting; the superimposition into a one image. Experimental results demonstrate the effectiveness of the proposed method in the task of image stitching.

Morphology, stratigraphy, and surface roughness properties of Venusian lava flow fields

NASA Astrophysics Data System (ADS)

Byrnes, Jeffrey M.; Crown, David A.

2002-10-01

Morphologic characteristics, flow stratigraphy, and radar backscatter properties of five lava flow fields on Venus (Turgmam Fluctus, Zipaltonal Fluctus, Tuli Mons/Uilata Fluctus, Var Mons, and Mylitta Fluctus) were examined to understand flow field emplacement mechanisms and relationships to other surface processes. These analyses indicate that the flow fields studied developed through emplacement of numerous, thin flow units, presumably over extended periods of time. Although the Venusian fields display flow morphologies similar to those observed within terrestrial flow fields, the Venusian flow units are significantly larger and have a larger range of radar backscatter coefficients. Both simple and compound flow emplacement appear to have occurred within the flow fields. A potential correlation between flow rheology and radar brightness is suggested by differences in planform morphology, apparent flow thickness, and apparent sensitivity to topography between bright and dark flows. Distributary flow morphologies may result from tube-fed flows, and postemplacement modification by processes such as flow inflation and crustal foundering is consistent with discrete zones of increased radar brightness within individual flow lobes. Mapping of these flow fields does not indicate any simple evolutionary trend in eruptive/resurfacing style within the flow fields, or any consistent temporal sequence relative to other tectonic and volcanic features.

Suppression of cooling by strong magnetic fields in white dwarf stars.

PubMed

Valyavin, G; Shulyak, D; Wade, G A; Antonyuk, K; Zharikov, S V; Galazutdinov, G A; Plachinda, S; Bagnulo, S; Machado, L Fox; Alvarez, M; Clark, D M; Lopez, J M; Hiriart, D; Han, Inwoo; Jeon, Young-Beom; Zurita, C; Mujica, R; Burlakova, T; Szeifert, T; Burenkov, A

2014-11-06

Isolated cool white dwarf stars more often have strong magnetic fields than young, hotter white dwarfs, which has been a puzzle because magnetic fields are expected to decay with time but a cool surface suggests that the star is old. In addition, some white dwarfs with strong fields vary in brightness as they rotate, which has been variously attributed to surface brightness inhomogeneities similar to sunspots, chemical inhomogeneities and other magneto-optical effects. Here we describe optical observations of the brightness and magnetic field of the cool white dwarf WD 1953-011 taken over about eight years, and the results of an analysis of its surface temperature and magnetic field distribution. We find that the magnetic field suppresses atmospheric convection, leading to dark spots in the most magnetized areas. We also find that strong fields are sufficient to suppress convection over the entire surface in cool magnetic white dwarfs, which inhibits their cooling evolution relative to weakly magnetic and non-magnetic white dwarfs, making them appear younger than they truly are. This explains the long-standing mystery of why magnetic fields are more common amongst cool white dwarfs, and implies that the currently accepted ages of strongly magnetic white dwarfs are systematically too young.

A Holographic Microscope for Detection of Microorganisms on Icy Worlds

NASA Astrophysics Data System (ADS)

Lindensmith, C. A.; Nadeau, J. L.; Deming, J. W.; Showalter, G. M.; Rider, S.; Bedrossian, M.

2015-12-01

Holography is a well-established imaging technique that uses the interference of light to record and reproduce three-dimensional images of objects. Its use began in the 1960s with the invention of the laser. Digital holographic microscopy (DHM) has several advantages over ordinary imaging microscopy which make it ideal for field and astrobiology use, including no need for focus or scanning so that instruments are readily made autonomous. DHM can produce simultaneous bright-field and quantitative phase-contrast images of the same field, providing additional information about transparent objects, e.g., refractive index and/or thickness; thus it inherently supports effective label-free imaging. We have built a fieldable DHM for detection of microorganisms in bodies of water and in brines collected from sea ice. Ice that appears solid to the eye contains interconnected brine-filled microscopic pores and veins which are occupied by populations of prokaryotes and eukaryotes. The presence of life in "solid" ice has important implications for exploration of icy worlds, where it is unlikely that the first missions will be able to access the subsurface oceans. Using this new instrument, we examined several dozen samples from three different sites around Nuuk, Greenland. In all samples, mixed populations of both prokaryotic and eukaryotic microorganisms were observed. Many of the organisms were motile immediately upon extraction from sea ice, and others became motile after warming or addition of sugars and/or amino acids. Meaningful motility was readily distinguished from turbulence or fluid flow. The spatial resolution of the instrument was better than 1 μm, leading to unambiguous recognition of subcellular structures in eukaryotes, including nuclei and chloroplasts. We present mission scenrios for both orbiters and landers in which DHM may be used as a valuable complement to chemical-based life detection techniques for discovery of cellular life on icy worlds.

Linear dark field control: simulation for implementation and testing on the UA wavefront control testbed

NASA Astrophysics Data System (ADS)

Miller, Kelsey; Guyon, Olivier

2016-07-01

This paper presents the early-stage simulation results of linear dark field control (LDFC) as a new approach to maintaining a stable dark hole within a stellar post-coronagraphic PSF. In practice, conventional speckle nulling is used to create a dark hole in the PSF, and LDFC is then employed to maintain the dark field by using information from the bright speckle field. The concept exploits the linear response of the bright speckle intensity to wavefront variations in the pupil, and therefore has many advantages over conventional speckle nulling as a method for stabilizing the dark hole. In theory, LDFC is faster, more sensitive, and more robust than using conventional speckle nulling techniques, like electric field conjugation, to maintain the dark hole. In this paper, LDFC theory, linear bright speckle characterization, and first results in simulation are presented as an initial step toward the deployment of LDFC on the UA Wavefront Control testbed in the coming year.

Diffusion tensor driven contour closing for cell microinjection targeting.

PubMed

Becattini, Gabriele; Mattos, Leonardo S; Caldwell, Darwin G

2010-01-01

This article introduces a novel approach to robust automatic detection of unstained living cells in bright-field (BF) microscope images with the goal of producing a target list for an automated microinjection system. The overall image analysis process is described and includes: preprocessing, ridge enhancement, image segmentation, shape analysis and injection point definition. The developed algorithm implements a new version of anisotropic contour completion (ACC) based on the partial differential equation (PDE) for heat diffusion which improves the cell segmentation process by elongating the edges only along their tangent direction. The developed ACC algorithm is equivalent to a dilation of the binary edge image with a continuous elliptic structural element that takes into account local orientation of the contours preventing extension towards normal direction. Experiments carried out on real images of 10 to 50 microm CHO-K1 adherent cells show a remarkable reliability in the algorithm along with up to 85% success for cell detection and injection point definition.

Combined optical sizing and acoustical characterization of single freely-floating microbubbles

NASA Astrophysics Data System (ADS)

Luan, Ying; Renaud, Guillaume; Raymond, Jason L.; Segers, Tim; Lajoinie, Guillaume; Beurskens, Robert; Mastik, Frits; Kokhuis, Tom J. A.; van der Steen, Antonius F. W.; Versluis, Michel; de Jong, Nico

2016-12-01

In this study we present a combined optical sizing and acoustical characterization technique for the study of the dynamics of single freely-floating ultrasound contrast agent microbubbles exposed to long burst ultrasound excitations up to the milliseconds range. A co-axial flow device was used to position individual microbubbles on a streamline within the confocal region of three ultrasound transducers and a high-resolution microscope objective. Bright-field images of microbubbles passing through the confocal region were captured using a high-speed camera synchronized to the acoustical data acquisition to assess the microbubble response to a 1-MHz ultrasound burst. Nonlinear bubble vibrations were identified at a driving pressure as low as 50 kPa. The results demonstrate good agreement with numerical simulations based on the shell-buckling model proposed by Marmottant et al. [J. Acoust. Soc. Am. 118, 3499-3505 (2005)]. The system demonstrates the potential for a high-throughput in vitro characterization of individual microbubbles.

Time multiplexing super-resolution nanoscopy based on the Brownian motion of gold nanoparticles

NASA Astrophysics Data System (ADS)

Ilovitsh, Tali; Ilovitsh, Asaf; Wagner, Omer; Zalevsky, Zeev

2017-02-01

Super-resolution localization microscopy can overcome the diffraction limit and achieve a tens of order improvement in resolution. It requires labeling the sample with fluorescent probes followed with their repeated cycles of activation and photobleaching. This work presents an alternative approach that is free from direct labeling and does not require the activation and photobleaching cycles. Fluorescently labeled gold nanoparticles in a solution are distributed on top of the sample. The nanoparticles move in a random Brownian motion, and interact with the sample. By obscuring different areas in the sample, the nanoparticles encode the sub-wavelength features. A sequence of images of the sample is captured and decoded by digital post processing to create the super-resolution image. The achievable resolution is limited by the additive noise and the size of the nanoparticles. Regular nanoparticles with diameter smaller than 100nm are barely seen in a conventional bright field microscope, thus fluorescently labeled gold nanoparticles were used, with proper

The importance of the boundary condition in the transport of intensity equation based phase measurement

NASA Astrophysics Data System (ADS)

Zhang, Jialin; Chen, Qian; Li, Jiaji; Zuo, Chao

2017-02-01

The transport of intensity equation (TIE) is a powerful tool for direct quantitative phase retrieval in microscopy imaging. However, there may be some problems when dealing with the boundary condition of the TIE. The previous work introduces a hard-edged aperture to the camera port of the traditional bright field microscope to generate the boundary signal for the TIE solver. Under this Neumann boundary condition, we can obtain the quantitative phase without any assumption or prior knowledge about the test object and the setup. In this paper, we will demonstrate the effectiveness of this method based on some experiments in practice. The micro lens array will be used for the comparison of two TIE solvers results based on introducing the aperture or not and this accurate quantitative phase imaging technique allows measuring cell dry mass which is used in biology to follow cell cycle, to investigate cell metabolism, or to address effects of drugs.

Far-field nanoscopy on a semiconductor quantum dot via a rapid-adiabatic-passage-based switch

NASA Astrophysics Data System (ADS)

Kaldewey, Timo; Kuhlmann, Andreas V.; Valentin, Sascha R.; Ludwig, Arne; Wieck, Andreas D.; Warburton, Richard J.

2018-02-01

The diffraction limit prevents a conventional optical microscope from imaging at the nanoscale. However, nanoscale imaging of molecules is possible by exploiting an intensity-dependent molecular switch1-3. This switch is translated into a microscopy scheme, stimulated emission depletion microscopy4-7. Variants on this scheme exist3,8-13, yet all exploit an incoherent response to the lasers. We present a scheme that relies on a coherent response to a laser. Quantum control of a two-level system proceeds via rapid adiabatic passage, an ideal molecular switch. We implement this scheme on an ensemble of quantum dots. Each quantum dot results in a bright spot in the image with extent down to 30 nm (λ/31). There is no significant loss of intensity with respect to confocal microscopy, resulting in a factor of 10 improvement in emitter position determination. The experiments establish rapid adiabatic passage as a versatile tool in the super-resolution toolbox.

Coherent Backscattering and Opposition Effects Observed in Some Atmosphereless Bodies of the Solar System

NASA Technical Reports Server (NTRS)

Dlugach, Zh. M.; Mishchenko, M. I.

2013-01-01

The results of photometric and polarimetric observations carried out for some bright atmosphere-less bodies of the Solar system near the zero phase angle reveal the simultaneous existence of two spectacular optical phenomena, the so-called brightness and polarization opposition effects. In a number of studies, these phenomena were explained by the influence of coherent backscattering. However, in general, the interference concept of coherent backscattering can be used only in the case where the particles are in the far-field zones of each other, i.e., when the scattering medium is rather rarefied. Because of this, it is important to prove rigorously and to demonstrate that the coherent backscattering effect may also exist in densely packed scattering media like regolith surface layers of celestial bodies. From the results of the computer modeling performed with the use of numerically exact solutions of the macroscopic Maxwell equations for discrete random media with different packing densities of particles, we studied the origin and evolution of all the opposition phenomena predicted by the coherent backscattering theory for low-packing-density media. It has been shown that the predictions of this theory remain valid for rather high-packing densities of particles that are typical, in particular, of regolith surfaces of the Solar system bodies. The results allow us to conclude that both opposition effects observed simultaneously in some high-albedo atmosphereless bodies of the Solar system are caused precisely by coherent backscattering of solar light in the regolith layers composed of microscopic particles.

Dark Murky Clouds in the Bright Milky Way

NASA Image and Video Library

2011-08-24

This infrared image from NASA Wide-field Infrared Survey Explorer shows exceptionally cold, dense cloud cores seen in silhouette against the bright diffuse infrared glow of the plane of the Milky Way galaxy.

Microscopic theory of linear light scattering from mesoscopic media and in near-field optics.

PubMed

Keller, Ole

2005-08-01

On the basis of quantum mechanical response theory a microscopic propagator theory of linear light scattering from mesoscopic systems is presented. The central integral equation problem is transferred to a matrix equation problem by discretization in transitions between pairs of (many-body) energy eigenstates. The local-field calculation which appears from this approach is valid down to the microscopic region. Previous theories based on the (macroscopic) dielectric constant concept make use of spatial (geometrical) discretization and cannot in general be trusted on the mesoscopic length scale. The present theory can be applied to light scattering studies in near-field optics. After a brief discussion of the macroscopic integral equation problem a microscopic potential description of the scattering process is established. In combination with the use of microscopic electromagnetic propagators the formalism allows one to make contact to the macroscopic theory of light scattering and to the spatial photon localization problem. The quantum structure of the microscopic conductivity response tensor enables one to establish a clear physical picture of the origin of local-field phenomena in mesoscopic and near-field optics. The Huygens scalar propagator formalism is revisited and its generality in microscopic physics pointed out.

Bright Points and Subflares in Ultraviolet Lines and X-Rays

NASA Technical Reports Server (NTRS)

Rovira, M.; Schmieder, B.; Demoulin, P.; Simnett, G. M.; Hagyard, M. J.; Reichmann, E.; Reichmann, E.; Tandberg-Hanssen, E.

1999-01-01

We have analyzed an active region which was observed in H.alpha (Multichannel Subtractive Double Pass Spectrograph), in UV lines (SMM/UVSP), and in X-rays (SMM/HXIS). In this active region there were only a few subflares and many small bright points visible in UV and in X-rays. Using an extrapolation based on the Fourier transform, we have computed magnetic field lines connecting different photospheric magnetic polarities from ground-based magnetograms. Along the magnetic inversion lines we find two different zones: (1) a high-shear region (> 70 deg) where subflares occur, and (2) a low-shear region along the magnetic inversion line where UV bright points are observed. In these latter regions the magnetic topology is complex with a mixture of polarities. According to the velocity field observed in the Si IV lamda.1402 line and the extrapolation of the magnetic field, we notice that each UV bright point is consistent with emission from low-rising loops with downflows at both ends. We notice some hard X-ray emissions above the bright-point regions with temperatures up to 8 x 10(exp 6) K, which suggests some induced reconnection due to continuous emergence of new flux. This reconnection is also enhanced by neighboring subflares.

Bright Electroluminescence from Single Graphene Nanoribbon Junctions

NASA Astrophysics Data System (ADS)

Chong, Michael C.; Afshar-Imani, Nasima; Scheurer, Fabrice; Cardoso, Claudia; Ferretti, Andrea; Prezzi, Deborah; Schull, Guillaume

2018-01-01

Thanks to their highly tunable band gaps, graphene nanoribbons (GNRs) with atomically precise edges are emerging as mechanically and chemically robust candidates for nanoscale light emitting devices of modulable emission color. While their optical properties have been addressed theoretically in depth, only few experimental studies exist, limited to ensemble measurements and without any attempt to integrate them in an electronic-like circuit. Here we report on the electroluminescence of individual GNRs suspended between the tip of a scanning tunneling microscope (STM) and a Au(111) substrate, constituting thus a realistic opto-electronic circuit. Emission spectra of such GNR junctions reveal a bright and narrow band emission of red light, whose energy can be tuned with the bias voltage applied to the junction, but always lying below the gap of infinite GNRs. Comparison with {\\it ab initio} calculations indicate that the emission involves electronic states localized at the GNR termini. Our results shed light on unpredicted optical transitions in GNRs and provide a promising route for the realization of bright, robust and controllable graphene-based light emitting devices.

Self-deflection of a bright soliton in a separate bright-dark spatial soliton pair based on a higher-order space charge field

NASA Astrophysics Data System (ADS)

Liu, Jin-Song; Hao, Zhong-Hua

2003-10-01

The self-deflection of a bright solitary beam can be controlled by a dark solitary beam via a parametric coupling effect between the bright and dark solitary beams in a separate bright-dark spatial soliton pair supported by an unbiased series photorefractive crystal circuit. The spatial shift of the bright solitary beam centre as a function of the input intensity of the dark solitary beam (hat rho) is investigated by taking into account the higher-order space charge field in the dynamics of the bright solitary beam via both numerical and perturbation methods under steady-state conditions. The deflection amount (Deltas0), defined as the value of the spatial shift at the output surface of the crystal, is a monotonic and nonlinear function of hat rho. When hat rho is weak or strong enough, Deltas0 is, in fact, unchanged with hat rho, whereas Deltas0 increases or decreases monotonically with hat rho in a middle range of hat rho. The corresponding variation range (deltas) depends strongly on the value of the input intensity of the bright solitary beam (r). There are some peak and valley values in the curve of deltas versus r under some conditions. When hat rho increases, the bright solitary beam can scan toward both the direction same as and opposite to the crystal's c-axis. Whether the direction is the same as or opposite to the c-axis depends on the parameter values and configuration of the crystal circuit, as well as the value of r. Some potential applications are discussed.

Individual Differences in Chromatic Brightness Matching.

DTIC Science & Technology

1984-10-03

very unreliable..." More recently, Boynton (15) has written, "Consider... a 555-nm green light on one side of a bi-partite field with a 4 6 5-nm blue...field immediately adjacent to it... We ask an observer to adjust the intensity of the blue field until it looks ’equally bright’ as the green one. This...clearly being blue, blue- green , green , yellow- green , yellow, and red. Their spectral transmittance curves are shown in Fig. 2. All were broad-band filters

Theoretical Investigation of Dual Tuning of Solitonic Processes in Multiferroic Structures

NASA Astrophysics Data System (ADS)

Cherkasskii, M. A.; Nikitin, A. A.; Ustinov, A. B.; Stashkevich, A.; Kalinikos, B. A.

2016-11-01

. The solitonic wave processes in a multiferroic structure based on ferroelectric and ferrite layers are studied. The influence of external electric and magnetic fields on frequency and wave-number ranges, where bright and dark solitons can exist, are analysed. The investigation was carried out with the nonlinear Schrodinger equation. Results show that an increase of the electric field shifts the boundary between bright and dark solitons to long-wave region. An increase in magnetic field results in the opposite effect.

Dark- and bright-rogue-wave solutions for media with long-wave-short-wave resonance.

PubMed

Chen, Shihua; Grelu, Philippe; Soto-Crespo, J M

2014-01-01

Exact explicit rogue-wave solutions of intricate structures are presented for the long-wave-short-wave resonance equation. These vector parametric solutions feature coupled dark- and bright-field counterparts of the Peregrine soliton. Numerical simulations show the robustness of dark and bright rogue waves in spite of the onset of modulational instability. Dark fields originate from the complex interplay between anomalous dispersion and the nonlinearity driven by the coupled long wave. This unusual mechanism, not available in scalar nonlinear wave equation models, can provide a route to the experimental realization of dark rogue waves in, for instance, negative index media or with capillary-gravity waves.

Peculiar Feldspar And Quartz Inclusions Within Zircons From Anorthosites, North Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

Eliwa, H. A.; Dawoud, M. I.; Khalaf, I. M.; Negendank, J. F.; Itaya, T.

2004-12-01

Zircons from three anorthosite outcrops along Wadi Dib area, north Eastern Desert of Egypt contain abundant and conspicuous inclusions of quartz, feldspar, amphibole and apatite. These anorthosites, as (50-100m thick) layers, represent the top of mafic-ultramafic intrusions exhibiting rhythmic layering visible by reputation of melanocratic and leucocratic layers. Field and microscopic studies exhibit that these anorthosites were affected by the action of residual magmatic solutions associated with the late stage crystallization of the younger granites, which modified their mineralogical composition. They are composed totally of plagioclase with subordinate amount of clinoenstatite, augite, amphibole, biotite, K-feldspar, and quartz. Accessories are magnetite, ilmenite, apatite and zircon. The abundance and the mode of occurrence of K-feldspar, quartz, and biotite with apatite and zircon among the megacrysts suggest their formation is ascribed to the interaction with the residual solutions. The microprobe data exhibit difference between feldspar and amphiboles contained herein zircons and those as anorthosite mineral constituents. The genetic relationship between zircons and their inclusions suggests later growth of zircons than inclusions and most probably at the final stage of rock modification. Zircons are magmatic and found in the interstitial feldspar and quartz among plagioclase megacrysts in aggregates or as individual grains. The microscopic and SEM images investigation exhibit that most zircons are subhedral to euhedral equant and prismatic crystals. Most zircons have same range of crystal morphologies and internal growth structures with predominance of prism /{100/} and pyramid /{101/} and occasionally prism /{110/} and pyramid /{111/}. No evidences for poly-faceted grains, inherited cores or later overgrowths were detected. CL images distinguished zircons with visible core-rim structures and others with regular and continuous growth zones contained herein various inclusions. The dark CL cores in the core-rim structured zircons are higher in U, Y and sometimes Hf relative to the CL bright rims. Microprobe data and x-ray chemical mapping of various zoned zircons suggest that U and Y with sometimes Hf have a negative correlation to the CL brightness, while Th doesn't exhibit any significant correlation.

Tunable electromagnetically induced transparency from a superconducting terahertz metamaterial

NASA Astrophysics Data System (ADS)

Zhang, Caihong; Wu, Jingbo; Jin, Biaobing; Jia, Xiaoqing; Kang, Lin; Xu, Weiwei; Wang, Huabing; Chen, Jian; Tonouchi, Masoyoshi; Wu, Peiheng

2017-06-01

We demonstrate in this paper the tunable electromagnetically induced transparency (EIT) made from a superconducting (SC) niobium nitride (NbN) film induced by an intense terahertz (THz) field. As the variation of the incident THz field alters the intrinsic ohmic loss of the SC NbN film, the field-dependent transmittance is observed. To elaborate the role of the bright and dark modes, a hybrid coupling model is introduced to fit the experimental transmission spectra and extract the characteristic parameters of each mode. It is shown that the resonator for the bright mode is altered greatly due to strong direct coupling to the incident intense THz field, whereas the dark mode resonator has little interaction with the incident THz field via a weak near-filed coupling to the bright-mode resonator. This implies that we can partially control a mode or a part of metamaterial by introducing the intense THz field, which offers an effective manner to selectively control the electromagnetic property of the metamaterial. This work may bring many potential applications for the tunable EIT-like metamaterial.

GLOBAL PROPERTIES OF M31'S STELLAR HALO FROM THE SPLASH SURVEY. I. SURFACE BRIGHTNESS PROFILE

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

Gilbert, Karoline M.; Guhathakurta, Puragra; Beaton, Rachael L.

2012-11-20

We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnostics is used to identify and reject foreground and background contaminants. This enables us to trace the stellar halo of M31 to larger projected distances and fainter surface brightnesses than previous photometric studies. The surface brightness profile of M31's halo follows a power law with index -2.2 {+-} 0.2 and extends to amore » projected distance of at least {approx}175 kpc ({approx}2/3 of M31's virial radius), with no evidence of a downward break at large radii. The best-fit elliptical isophotes have b/a = 0.94 with the major axis of the halo aligned along the minor axis of M31's disk, consistent with a prolate halo, although the data are also consistent with M31's halo having spherical symmetry. The fact that tidal debris features are kinematically cold is used to identify substructure in the spectroscopic fields out to projected radii of 90 kpc and investigate the effect of this substructure on the surface brightness profile. The scatter in the surface brightness profile is reduced when kinematically identified tidal debris features in M31 are statistically subtracted; the remaining profile indicates that a comparatively diffuse stellar component to M31's stellar halo exists to large distances. Beyond 90 kpc, kinematically cold tidal debris features cannot be identified due to small number statistics; nevertheless, the significant field-to-field variation in surface brightness beyond 90 kpc suggests that the outermost region of M31's halo is also comprised to a significant degree of stars stripped from accreted objects.« less

Enhancing the performance of the light field microscope using wavefront coding.

PubMed

Cohen, Noy; Yang, Samuel; Andalman, Aaron; Broxton, Michael; Grosenick, Logan; Deisseroth, Karl; Horowitz, Mark; Levoy, Marc

2014-10-06

Light field microscopy has been proposed as a new high-speed volumetric computational imaging method that enables reconstruction of 3-D volumes from captured projections of the 4-D light field. Recently, a detailed physical optics model of the light field microscope has been derived, which led to the development of a deconvolution algorithm that reconstructs 3-D volumes with high spatial resolution. However, the spatial resolution of the reconstructions has been shown to be non-uniform across depth, with some z planes showing high resolution and others, particularly at the center of the imaged volume, showing very low resolution. In this paper, we enhance the performance of the light field microscope using wavefront coding techniques. By including phase masks in the optical path of the microscope we are able to address this non-uniform resolution limitation. We have also found that superior control over the performance of the light field microscope can be achieved by using two phase masks rather than one, placed at the objective's back focal plane and at the microscope's native image plane. We present an extended optical model for our wavefront coded light field microscope and develop a performance metric based on Fisher information, which we use to choose adequate phase masks parameters. We validate our approach using both simulated data and experimental resolution measurements of a USAF 1951 resolution target; and demonstrate the utility for biological applications with in vivo volumetric calcium imaging of larval zebrafish brain.

Microwave radiometric studies and ground truth measurements of the NASA/USGS Southern California test site

NASA Technical Reports Server (NTRS)

Edgerton, A. T.; Trexler, D. T.; Sakamoto, S.; Jenkins, J. E.

1969-01-01

The field measurement program conducted at the NASA/USGS Southern California Test Site is discussed. Ground truth data and multifrequency microwave brightness data were acquired by a mobile field laboratory operating in conjunction with airborne instruments. The ground based investigations were performed at a number of locales representing a variety of terrains including open desert, cultivated fields, barren fields, portions of the San Andreas Fault Zone, and the Salton Sea. The measurements acquired ground truth data and microwave brightness data at wavelengths of 0.8 cm, 2.2 cm, and 21 cm.

Surface studies on Surveyor 3 tubing sections

NASA Technical Reports Server (NTRS)

Buvinger, E. A.

1972-01-01

Sections C and E of the unpainted, polished aluminum tubing from the strut of the radar altimeter and Doppler velocity sensor were examined in a transmission electron microscope for micrometeorite damage and ion bombardment. Both sections were contaminated and eroded on one side; it is suggested that these conditions were caused by sandblasting by lunar dust and retrorocket plume contamination during Surveyor 3 landing. Microcraters of different configurations were found on the bright sides of the tubes. Several degrees of violence were involved in the formation of the craters, and the particle size could be responsible for some differences. All micropits found were on the bright areas and data indicate 0.2 hypervelocity impact/sq cm and 2/sq cm for other types of craters. The greatest degree of damage resulted from particle impact and was limited to a maximum depth of 2 microns.

Plasmonic Imaging of Electrochemical Reactions of Single Nanoparticles.

PubMed

Fang, Yimin; Wang, Hui; Yu, Hui; Liu, Xianwei; Wang, Wei; Chen, Hong-Yuan; Tao, N J

2016-11-15

Electrochemical reactions are involved in many natural phenomena, and are responsible for various applications, including energy conversion and storage, material processing and protection, and chemical detection and analysis. An electrochemical reaction is accompanied by electron transfer between a chemical species and an electrode. For this reason, it has been studied by measuring current, charge, or related electrical quantities. This approach has led to the development of various electrochemical methods, which have played an essential role in the understanding and applications of electrochemistry. While powerful, most of the traditional methods lack spatial and temporal resolutions desired for studying heterogeneous electrochemical reactions on electrode surfaces and in nanoscale materials. To overcome the limitations, scanning probe microscopes have been invented to map local electrochemical reactions with nanometer resolution. Examples include the scanning electrochemical microscope and scanning electrochemical cell microscope, which directly image local electrochemical reaction current using a scanning electrode or pipet. The use of a scanning probe in these microscopes provides high spatial resolution, but at the expense of temporal resolution and throughput. This Account discusses an alternative approach to study electrochemical reactions. Instead of measuring electron transfer electrically, it detects the accompanying changes in the reactant and product concentrations on the electrode surface optically via surface plasmon resonance (SPR). SPR is highly surface sensitive, and it provides quantitative information on the surface concentrations of reactants and products vs time and electrode potential, from which local reaction kinetics can be analyzed and quantified. The plasmonic approach allows imaging of local electrochemical reactions with high temporal resolution and sensitivity, making it attractive for studying electrochemical reactions in biological systems and nanoscale materials with high throughput. The plasmonic approach has two imaging modes: electrochemical current imaging and interfacial impedance imaging. The former images local electrochemical current associated with electrochemical reactions (faradic current), and the latter maps local interfacial impedance, including nonfaradic contributions (e.g., double layer charging). The plasmonic imaging technique can perform voltammetry (cyclic or square wave) in an analogous manner to the traditional electrochemical methods. It can also be integrated with bright field, dark field, and fluorescence imaging capabilities in one optical setup to provide additional capabilities. To date the plasmonic imaging technique has found various applications, including mapping of heterogeneous surface reactions, analysis of trace substances, detection of catalytic reactions, and measurement of graphene quantum capacitance. The plasmonic and other emerging optical imaging techniques (e.g., dark field and fluorescence microscopy), together with the scanning probe-based electrochemical imaging and single nanoparticle analysis techniques, provide new capabilities for one to study single nanoparticle electrochemistry with unprecedented spatial and temporal resolutions. In this Account, we focus on imaging of electrochemical reactions at single nanoparticles.

H{α} Surges Aroused by Newly-emerging Satellite Bipolar Magnetic Field

NASA Astrophysics Data System (ADS)

Wang, J. F.; Zhou, T. H.; Ji, H. S.

2013-07-01

An Hα surge event occurred at AR NOAA 11259 on 2011 July 22. According to the BBSO (Big Bear Solar Observatory) Hα line-center observations, three surges continuously ejected from the same region to the north of the main-sunspot of AR 11259. All of surges ejected along a straight trajectory, and looked like the reversed Eiffel Tower. The first and second surges had the same process. Two bright points firstly appeared to the north of the main-sunspot. After several minutes, a surge appeared between the two bright points, and then rapidly ejected when the two points got most brightness.When the surge reached the maximum height, it disappeared quickly. However, the third surge appeared without bright points, and its height was only half of the others. Compared with SDO/HMI (Solar Dynamics Observatory/Helioseismic and Magnetic Imager) line-of-sight magnetogram, more than one hour before the first surge appeared, a satellite bipolar magnetic field emerged from the surge-ejection region. The newly-emerging positive magnetic flux showed a distinct decrease several minutes earlier than the ejection of the surges. We assumed that the surges was associated with the reconnection between the newly-emerging bipolar magnetic field and the existing (sunspot) magnetic field.

The Strongest Magnetic Field in Sunspots

NASA Astrophysics Data System (ADS)

Okamoto, J.; Sakurai, T.

2017-12-01

Sunspots are concentrations of magnetic fields on the solar surface. Generally, the strongest magnetic field in each sunspot is located in the dark umbra in most cases. A typical field strength in sunspots is around 3,000 G. On the other hand, some exceptions also have been found in complex sunspots with bright regions such as light bridges that separate opposite polarity umbrae, for instance with a strength of 4,300 G. However, the formation mechanism of such strong fields outside umbrae is still puzzling. Here we report an extremely strong magnetic field in a sunspot, which was located in a bright region sandwiched by two opposite-polarity umbrae. The strength is 6,250 G, which is the largest ever observed since the discovery of magnetic field on the Sun in 1908 by Hale. We obtained 31 scanned maps of the active region observed by Hinode/SOT/SP with a cadence of 3 hours over 5 days (February 1-6, 2014). Considering the spatial and temporal evolution of the vector magnetic field and the Doppler velocity in the bright region, we suggested that this strong field region was generated as a result of compression of one umbra pushed by the outward flow from the other umbra (Evershed flow), like the subduction of the Earth's crust in plate tectonics.

Moon night sky brightness simulation for the Xinglong station

NASA Astrophysics Data System (ADS)

Yao, Song; Zhang, Hao-Tong; Yuan, Hai-Long; Zhao, Yong-Heng; Dong, Yi-Qiao; Bai, Zhong-Rui; Deng, Li-Cai; Lei, Ya-Juan

2013-10-01

Using a sky brightness monitor at the Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences, we collected data from 22 dark clear nights and 90 moon nights. We first measured the sky brightness variation with time for dark nights and found a clear correlation between sky brightness and human activity. Then with a modified sky brightness model of moon nights and data from these nights, we derived the typical value for several important parameters in the model. With these results, we calculated the sky brightness distribution under a given moon condition for the Xinglong station. Furthermore, we simulated the sky brightness distribution of a moon night for a telescope with a 5° field of view (such as LAMOST). These simulations will be helpful for determining the limiting magnitude and exposure time, as well as planning the survey for LAMOST during moon nights.

Photoluminescence investigation of type-II GaSb/GaAs quantum dots grown by liquid phase epitaxy

NASA Astrophysics Data System (ADS)

Wang, Yang; Hu, Shuhong; Xie, Hao; Lin, Hongyu; lu, Hongbo; Wang, Chao; Sun, Yan; Dai, Ning

2018-06-01

GaSb quantum dots (QDs) with an areal density of ∼1 × 1010 cm-2 are successfully grown by the modified (rapid slider) liquid phase epitaxy technique. The morphology of the QDs has been investigated by scanning electron microscope (SEM) and atom force microscope (AFM). The power-dependence and temperature-dependence photoluminescence (PL) spectra have been studied. The bright room-temperature PL suggests a good luminescence quality of GaSb QDs/GaAs matrix system. The type-II alignment of the GaSb QDs/GaAs matrix system is verified by the blue-shift of the QDs peak with the increase of excitation power. From the temperature-dependence PL spectra, the activation energy of QDs is determined to be 111 meV.

Electroluminescence from InGaN/GaN multi-quantum-wells nanorods light-emitting diodes positioned by non-uniform electric fields.

PubMed

Park, Hyunik; Kim, Byung-Jae; Kim, Jihyun

2012-11-05

We report that the nanorod light-emitting diodes (LEDs) with InGaN/GaN multi-quantum-wells (MQWs) emitted bright electroluminescence (EL) after they were positioned and aligned by non-uniform electric fields. Firstly, thin film LED structures with MQWs on sapphire substrate were coated with SiO(2) nanospheres, followed by inductively-coupled plasma etch to create nanorod-shapes with MQWs, which were transferred to the pre-patterned SiO(2)/Si wafer. This method allowed us to obtain nanorod LEDs with uniform length, diameter and qualities. Dielectrophoretic force created by non-uniform electric field was very effective at positioning the processed nanorods on the pre-patterned contacts. After aligned by non-uniform electric field, we observed bright EL from many nanorods, which had both cases (p-GaN/MQWs/n-GaN or n-GaN/MQWs/p-GaN). Therefore, bright ELs at different locations were observed under the various bias conditions.

Three-Dimensional Structure and Evolution of Extreme-Ultraviolet Bright Points Observed by STEREO/SECCHI/EUVI

NASA Technical Reports Server (NTRS)

Kwon, Ryun Young; Chae, Jongchul; Davila, Joseph M.; Zhang, Jie; Moon, Yong-Jae; Poomvises, Watanachak; Jones, Shaela I.

2012-01-01

We unveil the three-dimensional structure of quiet-Sun EUV bright points and their temporal evolution by applying a triangulation method to time series of images taken by SECCHI/EUVI on board the STEREO twin spacecraft. For this study we examine the heights and lengths as the components of the three-dimensional structure of EUV bright points and their temporal evolutions. Among them we present three bright points which show three distinct changes in the height and length: decreasing, increasing, and steady. We show that the three distinct changes are consistent with the motions (converging, diverging, and shearing, respectively) of their photospheric magnetic flux concentrations. Both growth and shrinkage of the magnetic fluxes occur during their lifetimes and they are dominant in the initial and later phases, respectively. They are all multi-temperature loop systems which have hot loops (approx. 10(exp 6.2) K) overlying cooler ones (approx 10(exp 6.0) K) with cool legs (approx 10(exp 4.9) K) during their whole evolutionary histories. Our results imply that the multi-thermal loop system is a general character of EUV bright points. We conclude that EUV bright points are flaring loops formed by magnetic reconnection and their geometry may represent the reconnected magnetic field lines rather than the separator field lines.

Andromeda (M31) optical and infrared disk survey. I. Insights in wide-field near-IR surface photometry

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

Sick, Jonathan; Courteau, Stéphane; Cuillandre, Jean-Charles

We present wide-field near-infrared J and K{sub s} images of the Andromeda Galaxy (M31) taken with WIRCam at the Canada-France-Hawaii Telescope as part of the Andromeda Optical and Infrared Disk Survey. This data set allows simultaneous observations of resolved stars and near-infrared (NIR) surface brightness across M31's entire bulge and disk (within R = 22 kpc), permitting a direct test of the stellar composition of near-infrared light in a nearby galaxy. Here we develop NIR observation and reduction methods to recover a uniform surface brightness map across the 3° × 1° disk of M31 with 27 WIRCam fields. Two sky-targetmore » nodding strategies are tested, and we find that strictly minimizing sky sampling latency cannot improve background subtraction accuracy to better than 2% of the background level due to spatio-temporal variations in the NIR skyglow. We fully describe our WIRCam reduction pipeline and advocate using flats built from night-sky images over a single night, rather than dome flats that do not capture the WIRCam illumination field. Contamination from scattered light and thermal background in sky flats has a negligible effect on the surface brightness shape compared to the stochastic differences in background shape between sky and galaxy disk fields, which are ∼0.3% of the background level. The most dramatic calibration step is the introduction of scalar sky offsets to each image that optimizes surface brightness continuity. Sky offsets reduce the mean surface brightness difference between observation blocks from 1% to <0.1% of the background level, though the absolute background level remains statistically uncertain to 0.15% of the background level. We present our WIRCam reduction pipeline and performance analysis to give specific recommendations for the improvement of NIR wide-field imaging methods.« less

[Authentication of Trace Material Evidence in Forensic Science Field with Infrared Microscopic Technique].

PubMed

Jiang, Zhi-quan; Hu, Ke-liang

2016-03-01

In the field of forensic science, conventional infrared spectral analysis technique is usually unable to meet the detection requirements, because only very a few trace material evidence with diverse shapes and complex compositions, can be extracted from the crime scene. Infrared microscopic technique is developed based on a combination of Fourier-transform infrared spectroscopic technique and microscopic technique. Infrared microscopic technique has a lot of advantages over conventional infrared spectroscopic technique, such as high detection sensitivity, micro-area analysisand nondestructive examination. It has effectively solved the problem of authentication of trace material evidence in the field of forensic science. Additionally, almost no external interference is introduced during measurements by infrared microscopic technique. It can satisfy the special need that the trace material evidence must be reserved for witness in court. It is illustrated in detail through real case analysis in this experimental center that, infrared microscopic technique has advantages in authentication of trace material evidence in forensic science field. In this paper, the vibration features in infrared spectra of material evidences, including paints, plastics, rubbers, fibers, drugs and toxicants, can be comparatively analyzed by means of infrared microscopic technique, in an attempt to provide powerful spectroscopic evidence for qualitative diagnosis of various criminal and traffic accident cases. The experimental results clearly suggest that infrared microscopic technique has an incomparable advantage and it has become an effective method for authentication of trace material evidence in the field of forensic science.

A light field microscope imaging spectrometer based on the microlens array

NASA Astrophysics Data System (ADS)

Yao, Yu-jia; Xu, Feng; Xia, Yin-xiang

2017-10-01

A new light field spectrometry microscope imaging system, which was composed by microscope objective, microlens array and spectrometry system was designed in this paper. 5-D information (4-D light field and 1-D spectrometer) of the sample could be captured by the snapshot system in only one exposure, avoiding the motion blur and aberration caused by the scanning imaging process of the traditional imaging spectrometry. Microscope objective had been used as the former group while microlens array used as the posterior group. The optical design of the system was simulated by Zemax, the parameter matching condition between microscope objective and microlens array was discussed significantly during the simulation process. The result simulated in the image plane was analyzed and discussed.

An Amoeba/Zoozanthellae Consortium as a Model System for Animal/Algal Symbiosis

DTIC Science & Technology

1991-06-18

extensive multiple fission of Morph-1 cells. Morphology-V: Minigiants - 15-40 microns, complex net-like morphology resulted from fussion of mini oells...seaweeds and sea water (1:1) and autoclaved (20 minutes, 120aC, 250 psi). Nuclear staining: For staining the nuclei, cells were allowed to attach and...water were added (lug/ml) and the amoebae were observed under a fluorescent microscope. Nuclear stains penetrated fixed cells easily and brightly

Sensorless adaptive optics for isoSTED nanoscopy

NASA Astrophysics Data System (ADS)

Antonello, Jacopo; Hao, Xiang; Allgeyer, Edward S.; Bewersdorf, Joerg; Rittscher, Jens; Booth, Martin J.

2018-02-01

The presence of aberrations is a major concern when using fluorescence microscopy to image deep inside tissue. Aberrations due to refractive index mismatch and heterogeneity of the specimen under investigation cause severe reduction in the amount of fluorescence emission that is collected by the microscope. Furthermore, aberrations adversely affect the resolution, leading to loss of fine detail in the acquired images. These phenomena are particularly troublesome for super-resolution microscopy techniques such as isotropic stimulated-emission-depletion microscopy (isoSTED), which relies on accurate control of the shape and co-alignment of multiple excitation and depletion foci to operate as expected and to achieve the super-resolution effect. Aberrations can be suppressed by implementing sensorless adaptive optics techniques, whereby aberration correction is achieved by maximising a certain image quality metric. In confocal microscopy for example, one can employ the total image brightness as an image quality metric. Aberration correction is subsequently achieved by iteratively changing the settings of a wavefront corrector device until the metric is maximised. This simplistic approach has limited applicability to isoSTED microscopy where, due to the complex interplay between the excitation and depletion foci, maximising the total image brightness can lead to introducing aberrations in the depletion foci. In this work we first consider the effects that different aberration modes have on isoSTED microscopes. We then propose an iterative, wavelet-based aberration correction algorithm and evaluate its benefits.

Implementation of bright six-partite entanglement by coupled intracavity sum frequency generation

NASA Astrophysics Data System (ADS)

Wang, Junfeng; Liu, Le; Liu, Yuzhu; Zhang, Yanan; Wu, Hongyan; Gong, Chengxuan; Zhang, Ruofan; Zhang, Houyuan; Fan, JingYu

2018-04-01

Bright six-partite continuous-variable (CV) entanglement generated by the coupled intracavity sum frequency generation is investigated. The entanglement characteristics of reflected pump fields and the output sum frequency fields are discussed theoretically in symmetric and asymmetric cases by applying van Loock and Furusawa criteria for multipartite CV entanglement. Such compact tunable multipartite CV entanglement, generated from an experimentally feasible coupled system, could be used in integrated quantum communication and networks.

Bright and durable field emission source derived from refractory taylor cones

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

Hirsch, Gregory

A method of producing field emitters having improved brightness and durability relying on the creation of a liquid Taylor cone from electrically conductive materials having high melting points. The method calls for melting the end of a wire substrate with a focused laser beam, while imposing a high positive potential on the material. The resulting molten Taylor cone is subsequently rapidly quenched by cessation of the laser power. Rapid quenching is facilitated in large part by radiative cooling, resulting in structures having characteristics closely matching that of the original liquid Taylor cone. Frozen Taylor cones thus obtained yield desirable tipmore » end forms for field emission sources in electron beam applications. Regeneration of the frozen Taylor cones in-situ is readily accomplished by repeating the initial formation procedures. The high temperature liquid Taylor cones can also be employed as bright ion sources with chemical elements previously considered impractical to implement.« less

Simultaneous observations of changes in coronal bright point emission at the 20 cm radio and He Lambda 10830 wavelengths

NASA Technical Reports Server (NTRS)

Habbal, Shadia R.; Harvey, Karen L.

1986-01-01

Preliminary results of observations of solar coronal bright points acquired simultaneously from ground based observatories at the radio wavelength of 20 cm and in the He I wavelength 10830 line on September 8, 1985, are reported. The impetus for obtaining simultaneous radio and optical data is to identify correlations, if any, in changes of the low transition-coronal signatures of bright points with the evolution of the magnetic field, and to distinguish between intermittent heating and changes in the magnetic field topology. Although simultaneous observations of H alpha emission and the photospheric magnetic field at Big Bear were also made, as well as radio observations from Owen Valley Radio Interferometer and Solar Maximum Mission (SSM) (O VIII line), only the comparison between He 10830 and the Very Large Array (VLA) radio data are presented.

Quantitative Image Restoration in Bright Field Optical Microscopy.

PubMed

Gutiérrez-Medina, Braulio; Sánchez Miranda, Manuel de Jesús

2017-11-07

Bright field (BF) optical microscopy is regarded as a poor method to observe unstained biological samples due to intrinsic low image contrast. We introduce quantitative image restoration in bright field (QRBF), a digital image processing method that restores out-of-focus BF images of unstained cells. Our procedure is based on deconvolution, using a point spread function modeled from theory. By comparing with reference images of bacteria observed in fluorescence, we show that QRBF faithfully recovers shape and enables quantify size of individual cells, even from a single input image. We applied QRBF in a high-throughput image cytometer to assess shape changes in Escherichia coli during hyperosmotic shock, finding size heterogeneity. We demonstrate that QRBF is also applicable to eukaryotic cells (yeast). Altogether, digital restoration emerges as a straightforward alternative to methods designed to generate contrast in BF imaging for quantitative analysis. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

An Assessment of Magnetic Conditions for Strong Coronal Heating in Solar Active Regions by Comparing Observed Loops with Computed Potential Field Lines

NASA Technical Reports Server (NTRS)

Gary, G. A.; Moore, R. L.; Porter, J. G.; Falconer, D. A.

1999-01-01

We report further results on the magnetic origins of coronal heating found from registering coronal images with photospheric vector magnetograms. For two complementary active regions, we use computed potential field lines to examine the global non-potentiality of bright extended coronal loops and the three-dimensional structure of the magnetic field at their feet, and assess the role of these magnetic conditions in the strong coronal heating in these loops. The two active regions are complementary, in that one is globally potential and the other is globally nonpotential, while each is predominantly bipolar, and each has an island of included polarity in its trailing polarity domain. We find the following: (1) The brightest main-arch loops of the globally potential active region are brighter than the brightest main- arch loops of the globally strongly nonpotential active region. (2) In each active region, only a few of the mainarch magnetic loops are strongly heated, and these are all rooted near the island. (3) The end of each main-arch bright loop apparently bifurcates above the island, so that it embraces the island and the magnetic null above the island. (4) At any one time, there are other main-arch magnetic loops that embrace the island in the same manner as do the bright loops but that are not selected for strong coronal heating. (5) There is continual microflaring in sheared core fields around the island, but the main-arch bright loops show little response to these microflares. From these observational and modeling results we draw the following conclusions: (1) The heating of the main-arch bright loops arises mainly from conditions at the island end of these loops and not from their global non-potentiality. (2) There is, at most, only a loose coupling between the coronal heating in the bright loops of the main arch and the coronal heating in the sheared core fields at their feet, although in both the heating is driven by conditions/events in and around the island. (3) The main-arch bright loops are likely to be heated via reconnection driven at the magnetic null over the island. The details of how and where (along the null line) the reconnection is driven determine which of the split-end loops are selected for strong heating. (4) The null does not appear to be directly involved in the heating of the sheared core fields or in the heating of an extended loop rooted in the island. Rather, these all appear to be heated by microflares in the sheared core field.

Microscopic Investigation of Materials Limitations of Superconducting RF Cavities

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

Anlage, Steven

2017-08-04

Our overall goal is to contribute to the understanding of defects that limit the high accelerating gradient performance of Nb SRF cavities. Our approach is to develop a microscopic connection between materials defects and SRF performance. We developed a near-field microwave microscope to establish this connection. The microscope is based on magnetic hard drive write heads, which are designed to create very strong rf magnetic fields in very small volumes on a surface.

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

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

Field performance of a low-cost and fully-automated blood counting system operated by trained and untrained users (Conference Presentation)

NASA Astrophysics Data System (ADS)

Xie, Dengling; Xie, Yanjun; Liu, Peng; Tong, Lieshu; Chu, Kaiqin; Smith, Zachary J.

2017-02-01

Current flow-based blood counting devices require expensive and centralized medical infrastructure and are not appropriate for field use. In this paper we report a method to count red blood cells, white blood cells as well as platelets through a low-cost and fully-automated blood counting system. The approach consists of using a compact, custom-built microscope with large field-of-view to record bright-field and fluorescence images of samples that are diluted with a single, stable reagent mixture and counted using automatic algorithms. Sample collection is performed manually using a spring loaded lancet, and volume-metering capillary tubes. The capillaries are then dropped into a tube of pre-measured reagents and gently shaken for 10-30 seconds. The sample is loaded into a measurement chamber and placed on a custom 3D printed platform. Sample translation and focusing is fully automated, and a user has only to press a button for the measurement and analysis to commence. Cost of the system is minimized through the use of custom-designed motorized components. We performed a series of comparative experiments by trained and untrained users on blood from adults and children. We compare the performance of our system, as operated by trained and untrained users, to the clinical gold standard using a Bland-Altman analysis, demonstrating good agreement of our system to the clinical standard. The system's low cost, complete automation, and good field performance indicate that it can be successfully translated for use in low-resource settings where central hematology laboratories are not accessible.

[Application of single-band brightness variance ratio to the interference dissociation of cloud for satellite data].

PubMed

Qu, Wei-ping; Liu, Wen-qing; Liu, Jian-guo; Lu, Yi-huai; Zhu, Jun; Qin, Min; Liu, Cheng

2006-11-01

In satellite remote-sensing detection, cloud as an interference plays a negative role in data retrieval. How to discern the cloud fields with high fidelity thus comes as a need to the following research. A new method rooting in atmospheric radiation characteristics of cloud layer, in the present paper, presents a sort of solution where single-band brightness variance ratio is used to detect the relative intensity of cloud clutter so as to delineate cloud field rapidly and exactly, and the formulae of brightness variance ratio of satellite image, image reflectance variance ratio, and brightness temperature variance ratio of thermal infrared image are also given to enable cloud elimination to produce data free from cloud interference. According to the variance of the penetrating capability for different spectra bands, an objective evaluation is done on cloud penetration of them with the factors that influence penetration effect. Finally, a multi-band data fusion task is completed using the image data of infrared penetration from cirrus nothus. Image data reconstruction is of good quality and exactitude to show the real data of visible band covered by cloud fields. Statistics indicates the consistency of waveband relativity with image data after the data fusion.

Studies of Isolated and Non-isolated Photospheric Bright Points in an Active Region Observed by the New Vacuum Solar Telescope

NASA Astrophysics Data System (ADS)

Liu, Yanxiao; Xiang, Yongyuan; Erdélyi, Robertus; Liu, Zhong; Li, Dong; Ning, Zongjun; Bi, Yi; Wu, Ning; Lin, Jun

2018-03-01

Properties of photospheric bright points (BPs) near an active region have been studied in TiO λ 7058 Å images observed by the New Vacuum Solar Telescope of the Yunnan Observatories. We developed a novel recognition method that was used to identify and track 2010 BPs. The observed evolving BPs are classified into isolated (individual) and non-isolated (where multiple BPs are observed to display splitting and merging behaviors) sets. About 35.1% of BPs are non-isolated. For both isolated and non-isolated BPs, the brightness varies from 0.8 to 1.3 times the average background intensity and follows a Gaussian distribution. The lifetimes of BPs follow a log-normal distribution, with characteristic lifetimes of (267 ± 140) s and (421 ± 255) s, respectively. Their size also follows log-normal distribution, with an average size of about (2.15 ± 0.74) × 104 km2 and (3.00 ± 1.31) × 104 km2 for area, and (163 ± 27) km and (191 ± 40) km for diameter, respectively. Our results indicate that regions with strong background magnetic field have higher BP number density and higher BP area coverage than regions with weak background field. Apparently, the brightness/size of BPs does not depend on the background field. Lifetimes in regions with strong background magnetic field are shorter than those in regions with weak background field, on average.

Controlling the stability of nonlinear optical modes via electromagnetically induced transparency

NASA Astrophysics Data System (ADS)

Zhang, Kun; Liang, Yi-zeng; Lin, Ji; Li, Hui-jun

2018-02-01

We propose a scheme to generate and stabilize the high-dimensional spatial solitons via electromagnetically induced transparency (EIT). The system we consider is a resonant atomic ensemble having Λ configuration. We illustrate that under EIT conditions the equation satisfied by the probe field envelope is reduced to a saturable nonlinear Schrödinger equation with the trapping potential, provided by a far-detuned laser field and a random magnetic field. We present high-dimensional soliton solutions exhibiting many interesting characteristics, including diversity (i.e., many different types of soliton solutions can be found, including bright, ring multipole bright, ring multipole defect mode, multiring bright, multiring defect mode, and vortices solitons), the phase transition between bright soliton and higher-order defect modes (i.e., the phase transition can be realized by controlling the nonlinear coefficient or the intensity of the trapping potential), and stability (i.e., various solitons can be stabilized by the Gaussian potential provided by the far detuned laser field, or the random potential provided by the magnetic field). We also find that some solitons are the extension of the linear eigenmode, whereas others entirely derive from the role of nonlinearity. Compared with previous studies, we not only show the diverse soliton solutions in the same system but also find the boundary of the phase transition for the type of solitons. In addition, we present the possibility of using the random potential to stabilize various solitons and vortices.

Are the Basins of Tui Regio and Hotei Arcus Sites of Former Titanian Seas?

NASA Technical Reports Server (NTRS)

Moore, Jeffrey Morgan; Howard, Alan

2012-01-01

Features observed in the basins of Tui Regio and Hotei Arcus on Titan have attracted the attention of the Cassini-era investigators. At both locations, VIMS observed discrete 5-micron bright approx.500-km wide features described as lobate in shape. Several studies have proposed that these materials are cryo-volcanic flows; in the case of the Hotei Arcus feature this inference was buttressed with SAR RADAR images showing bright and dark patches with lobate margins. We propose an alternative explanation. First we note that all landforms on Titan that are unambiguously identifiable can be explained by exogenic processes (aeolian, fluvial, impact cratering, and mass wasting). Suggestions of endogenically produced cryovolcanic constructs and flows have, without exception, lacked conclusive diagnostic evidence. Recently published topographic profiles across Tui Regio and the lobate feature region north of Hotei Arcus indicate these features appear to occur in large regional basins, at least along the direction of the profiles. SAR images show that the terrains surrounding both 5-micron bright features exhibit fluvial networks that appear to converge and debauch into the probable basins. The 5-micron bright features themselves correspond to fields of discrete radar-bright depressions whose bounding edges are commonly rounded and cumulate in planform in SAR images. These fields of discrete radar-bright depressions strongly resemble fields of features seen at Titan s high latitudes usually attributed to be dry lakes. Thus the combination of (1) the resemblance to high-latitude dry lakes, (2) location in the centers of probable regional depressions, and (3) convergence of fluvial networks are inferred by us to best explain the 5-micron bright regions at Tui Regio and Hotei Arcus as sites of dry seas or at least paleolake clusters. Such equatorial seas, if real, may be evidence of substantially larger inventories of liquid alkanes in Titan s past.

LC-lens array with light field algorithm for 3D biomedical applications

NASA Astrophysics Data System (ADS)

Huang, Yi-Pai; Hsieh, Po-Yuan; Hassanfiroozi, Amir; Martinez, Manuel; Javidi, Bahram; Chu, Chao-Yu; Hsuan, Yun; Chu, Wen-Chun

2016-03-01

In this paper, liquid crystal lens (LC-lens) array was utilized in 3D bio-medical applications including 3D endoscope and light field microscope. Comparing with conventional plastic lens array, which was usually placed in 3D endoscope or light field microscope system to record image disparity, our LC-lens array has higher flexibility of electrically changing its focal length. By using LC-lens array, the working distance and image quality of 3D endoscope and microscope could be enhanced. Furthermore, the 2D/3D switching ability could be achieved if we turn off/on the electrical power on LClens array. In 3D endoscope case, a hexagonal micro LC-lens array with 350um diameter was placed at the front end of a 1mm diameter endoscope. With applying electric field on LC-lens array, the 3D specimen would be recorded as from seven micro-cameras with different disparity. We could calculate 3D construction of specimen with those micro images. In the other hand, if we turn off the electric field on LC-lens array, the conventional high resolution 2D endoscope image would be recorded. In light field microscope case, the LC-lens array was placed in front of the CMOS sensor. The main purpose of LC-lens array is to extend the refocusing distance of light field microscope, which is usually very narrow in focused light field microscope system, by montaging many light field images sequentially focusing on different depth. With adjusting focal length of LC-lens array from 2.4mm to 2.9mm, the refocusing distance was extended from 1mm to 11.3mm. Moreover, we could use a LC wedge to electrically shift the optics axis and increase the resolution of light field.

THE DOMINANCE OF METAL-RICH STREAMS IN STELLAR HALOS: A COMPARISON BETWEEN SUBSTRUCTURE IN M31 AND {lambda}CDM MODELS

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

Gilbert, Karoline M.; Font, Andreea S.; Johnston, Kathryn V.

2009-08-10

Extensive photometric and spectroscopic surveys of the Andromeda galaxy (M31) have discovered tidal debris features throughout M31's stellar halo. We present stellar kinematics and metallicities in fields with identified substructure from our on-going SPLASH survey of M31 red giant branch stars with the DEIMOS spectrograph on the Keck II 10 m telescope. Radial velocity criteria are used to isolate members of the kinematically cold substructures. The substructures are shown to be metal-rich relative to the rest of the dynamically hot stellar population in the fields in which they are found. We calculate the mean metallicity and average surface brightness ofmore » the various kinematical components in each field, and show that, on average, higher surface brightness features tend to be more metal-rich than lower surface brightness features. Simulations of stellar halo formation via accretion in a cosmological context are used to illustrate that the observed trend can be explained as a natural consequence of the observed dwarf galaxy mass-metallicity relation. A significant spread in metallicity at a given surface brightness is seen in the data; we show that this is due to time effects, namely, the variation in the time since accretion of the tidal streams' progenitor onto the host halo. We show that in this theoretical framework a relationship between the alpha-enhancement and surface brightness of tidal streams is expected, which arises from the varying times of accretion of the progenitor satellites onto the host halo. Thus, measurements of the alpha-enrichment, metallicity, and surface brightness of tidal debris can be used to reconstruct the luminosity and time of accretion onto the host halo of the progenitors of tidal streams.« less

Bright field segmentation tomography (BFST) for use as surface identification in stereomicroscopy

NASA Astrophysics Data System (ADS)

Thiesse, Jacqueline R.; Namati, Eman; de Ryk, Jessica; Hoffman, Eric A.; McLennan, Geoffrey

2004-07-01

Stereomicroscopy is an important method for use in image acquisition because it provides a 3D image of an object when other microscopic techniques can only provide the image in 2D. One challenge that is being faced with this type of imaging is determining the top surface of a sample that has otherwise indistinguishable surface and planar characteristics. We have developed a system that creates oblique illumination and in conjunction with image processing, the top surface can be viewed. The BFST consists of the Leica MZ12 stereomicroscope with a unique attached lighting source. The lighting source consists of eight light emitting diodes (LED's) that are separated by 45-degree angles. Each LED in this system illuminates with a 20-degree viewing angle once per cycle with a shadow over the rest of the sample. Subsequently, eight segmented images are taken per cycle. After the images are captured they are stacked through image addition to achieve the full field of view, and the surface is then easily identified. Image processing techniques, such as skeletonization can be used for further enhancement and measurement. With the use of BFST, advances can be made in detecting surface features from metals to tissue samples, such as in the analytical assessment of pulmonary emphysema using the technique of mean linear intercept.

Inversion domain boundaries in ZnO with additions of Fe2O3 studied by high-resolution ADF imaging.

PubMed

Wolf, Frank; Freitag, Bert H; Mader, Werner

2007-01-01

Columns of metal atoms in the polytypoid compound Fe2O3(ZnO)15 could be resolved by high angle annular dark field imaging in a transmission electron microscopy (TEM)/STEM electron microscope--a result which could not be realized by high-resolution bright field imaging due to inherent strain from inversion domains and inversion domain boundaries (IDBs) in the crystals. The basal plane IDB was imaged in [11 00] yielding the spacing of the two adjacent ZnO domains, while imaging in [21 1 0] yields the position of single metal ions. The images allow the construction of the entire domain structure including the stacking sequence and positions of the oxygen ions. The IDB consists of a single layer of octahedrally co-ordinated Fe3+ ions, and the inverted ZnO domains are related by point symmetry at the iron position. The FeO6 octahedrons are compressed along the ZnO c-axis resulting in a FeO bond length of 0.208 nm which is in the range of FeO distances in iron containing oxides. The model of the basal plane boundary resembles that of the IDB in polytypoid ZnO-In2O3 compounds.

Sizing of single fluorescently stained DNA fragments by scanning microscopy

PubMed Central

Laib, Stephan; Rankl, Michael; Ruckstuhl, Thomas; Seeger, Stefan

2003-01-01

We describe an approach to determine DNA fragment sizes based on the fluorescence detection of single adsorbed fragments on specifically coated glass cover slips. The brightness of single fragments stained with the DNA bisintercalation dye TOTO-1 is determined by scanning the surface with a confocal microscope. The brightness of adsorbed fragments is found to be proportional to the fragment length. The method needs only minute amount of DNA, beyond inexpensive and easily available surface coatings, like poly-l-lysine, 3-aminoproyltriethoxysilane and polyornithine, are utilizable. We performed DNA-sizing of fragment lengths between 2 and 14 kb. Further, we resolved the size distribution before and after an enzymatic restriction digest. At this a separation of buffers or enzymes was unnecessary. DNA sizes were determined within an uncertainty of 7–14%. The proposed method is straightforward and can be applied to standardized microtiter plates. PMID:14602931

Extraction of topographic and material contrasts on surfaces from SEM images obtained by energy filtering detection with low-energy primary electrons.

PubMed

Nagoshi, Masayasu; Aoyama, Tomohiro; Sato, Kaoru

2013-01-01

Secondary electron microscope (SEM) images have been obtained for practical materials using low primary electron energies and an in-lens type annular detector with changing negative bias voltage supplied to a grid placed in front of the detector. The kinetic-energy distribution of the detected electrons was evaluated by the gradient of the bias-energy dependence of the brightness of the images. This is divided into mainly two parts at about 500 V, high and low brightness in the low- and high-energy regions, respectively and shows difference among the surface regions having different composition and topography. The combination of the negative grid bias and the pixel-by-pixel image subtraction provides the band-pass filtered images and extracts the material and topographic information of the specimen surfaces. Copyright © 2012 Elsevier B.V. All rights reserved.

Fluorescent staining for leukocyte chemotaxis. Eosinophil-specific fluorescence with aniline blue.

PubMed

McCrone, E L; Lucey, D R; Weller, P F

1988-11-10

To overcome problems associated with the quantitation of human eosinophil chemotaxis in micropore filters, we have developed a fluorescent method of specifically staining eosinophils in chemotactic filters. A neutral solution of aniline blue yielded bright green fluorescent staining of the cytoplasmic granules of eosinophils. Other leukocytes and contaminating neutrophils potentially present with eosinophils did not fluoresce with aniline blue. The fluorescent staining eosinophils within filters provided bright, non-fading images that facilitated visual microscopic counting and were of sufficiently high contrast, unlike those with conventional eosinophil stains, to allow image analyzer based enumeration of eosinophil chemotactic responses at levels through the filters. Although not cell type-specific, congo red and ethidium bromide also provided high contrast, fluorescent images of all leukocyte types within chemotactic filters. Fluorescent staining with aniline blue constitutes a rapid, stable and eosinophil-specific stain that facilitates the visual or image analyzer-based quantitation of eosinophil chemotaxis.

Enhancing the performance of the light field microscope using wavefront coding

PubMed Central

Cohen, Noy; Yang, Samuel; Andalman, Aaron; Broxton, Michael; Grosenick, Logan; Deisseroth, Karl; Horowitz, Mark; Levoy, Marc

2014-01-01

Light field microscopy has been proposed as a new high-speed volumetric computational imaging method that enables reconstruction of 3-D volumes from captured projections of the 4-D light field. Recently, a detailed physical optics model of the light field microscope has been derived, which led to the development of a deconvolution algorithm that reconstructs 3-D volumes with high spatial resolution. However, the spatial resolution of the reconstructions has been shown to be non-uniform across depth, with some z planes showing high resolution and others, particularly at the center of the imaged volume, showing very low resolution. In this paper, we enhance the performance of the light field microscope using wavefront coding techniques. By including phase masks in the optical path of the microscope we are able to address this non-uniform resolution limitation. We have also found that superior control over the performance of the light field microscope can be achieved by using two phase masks rather than one, placed at the objective’s back focal plane and at the microscope’s native image plane. We present an extended optical model for our wavefront coded light field microscope and develop a performance metric based on Fisher information, which we use to choose adequate phase masks parameters. We validate our approach using both simulated data and experimental resolution measurements of a USAF 1951 resolution target; and demonstrate the utility for biological applications with in vivo volumetric calcium imaging of larval zebrafish brain. PMID:25322056

Phase-shifting interference microscope with extendable field of measurement

NASA Astrophysics Data System (ADS)

Lin, Shyh-Tsong; Hsu, Wei-Feng; Wang, Ming-Shiang

2018-04-01

An innovative phase-shifting interference microscope aimed at extending the field of measurement is proposed in this paper. The microscope comprises a light source module, a phase modulation module, and an interferometric module, which reconstructs the micro-structure contours of samples using the five-step phase-shifting algorithm. This paper discusses the measurement theory and outlines the configuration, experimental setup, and experimental results obtained using the proposed interference microscope. The results confirm the efficacy of the microscope, achieving a standard deviation of 2.4 nm from a step height of 86.2 nm in multiple examinations.

Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope.

PubMed

Hagedorn, Till; El Ouali, Mehdi; Paul, William; Oliver, David; Miyahara, Yoichi; Grütter, Peter

2011-11-01

A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10(-10) mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission. © 2011 American Institute of Physics

Enhanced magnetic separation and photocatalytic activity of nitrogen doped titania photocatalyst supported on strontium ferrite.

PubMed

Abd Aziz, Azrina; Yong, Kok Soon; Ibrahim, Shaliza; Pichiah, Saravanan

2012-01-15

An enhanced ferromagnetic property, visible light active TiO(2) photocatalyst was successfully synthesized by supporting strontium ferrite (SrFe(12)O(19)) onto TiO(2) doped with nitrogen (N) and compared with N-doped TiO(2). The synthesized catalysts were further characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS), BET surface area analysis, vibrating sample magnetometer (VSM), X-ray photon spectroscopy (XPS) and visible light spectroscopy analysis for their respective properties. The XRD and EDS revealed the structural and inorganic composition of N-TiO(2) supported on SrFe(12)O(19). The supported N-TiO(2) exhibited a strong ferromagnetic property with tremendous stability against magnetic property losses. It also resulted in reduced band gap (2.8 eV) and better visible light absorption between 400 and 800 nm compared to N-doped TiO(2). The photocatalytic activity was investigated with a recalcitrant phenolic compound namely 2,4-dichlorophenol (2,4-DCP) as a model pollutant under direct bright and diffuse sunlight exposure. A complete degradation of 2,4-DCP was achieved with an initial concentration of 50mg/L for both photocatalysts in 180 min and 270 min respectively under bright sunlight. Similarly the diffuse sunlight study resulted in complete degradation for supported N-TiO(2) and >85% degradation N-TiO(2), respectively. Finally the supported photocatalyst was separated under permanent magnetic field with a mass recovery ≈ 98% for further reuse. Copyright © 2011 Elsevier B.V. All rights reserved.

Why does substorm-associated auroral surge travel westward?

NASA Astrophysics Data System (ADS)

Ebihara, Y.; Tanaka, T.

2018-01-01

A substorm is a long-standing unsolved issue in solar-terrestrial physics. One of the big challenges is to explain reasonably the evolution of the morphological structure of the aurora associated with the substorm. The sudden appearance of a bright aurora and an auroral surge traveling westward (westward traveling surge, WTS) are noticeable features of the aurora during the substorm expansion phase. By using a global magnetohydrodynamics (MHD) simulation, we obtained the following results regarding the WTS. When the interplanetary magnetic field turns southward, a persistent dynamo appears in the cusp/mantle region, driving the two-cell magnetospheric convection. Then, the substorm growth phase begins. When magnetic reconnection takes place in the magnetotail, plasma is accelerated earthward in the plasma sheet, and accelerated toward the equatorial plane in the lobe. The second dynamo appears in the near-Earth region, which is closely associated with the generation of the field-aligned current (FAC) on the nightside. When the FAC reaches the ionosphere, the aurora becomes bright, and the onset of the expansion phase begins. In the ionosphere, the conductivity is intensified in the bright aurora due to the precipitation of accelerated electrons. The conductivity gradient gives rise to the overflow of the Hall current, which acts as the third dynamo. The overflow results in the accumulation of space charge, which causes a divergent electric field. The divergent electric field generates a thin, structured upward FAC adjacent to the bright aurora. The opposite process takes place on the opposite side of the bright aurora. In short, the upward FAC increases (appearance of aurora) at the leading edge of the surge, and decreases (disappearance of aurora) at the trailing edge of the surge. By repeating these processes, the surge seems to travel westward.

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

Royer, Michael P.; Houser, Kevin W.

An experiment was conducted to examine the effect of tuning optical radiation on brightness perception for younger (18-25 years of age) and older (50 years of age or older) observers. Participants made forced-choice evaluations of the brightness of a full factorial of stimulus pairs selected from two groups of four metameric stimuli. The large-field stimuli were created by systematically varying either the red or the blue primary of an RGB LED mixture. The results indicate that light stimuli of equal illuminance and chromaticity do not appear equally bright to either younger or older subjects. The rank-order of brightness is notmore » predicted by any current model of human vision or theory of brightness perception including Scotopic to Photopic or Cirtopic to Photopic ratio theory, prime color theory, correlated color temperature, V(λ)-based photometry, color quality metrics, linear brightness models, or color appearance models. Age may affect brightness perception when short-wavelength primaries are used, especially those with a peak wavelength shorter than 450 nm. The results suggest further development of metrics to predict brightness perception is warranted, and that including age as a variable in predictive models may be valuable.« less

Pathology of carbon monoxide poisoning in two cats.

PubMed

Sobhakumari, Arya; Poppenga, Robert H; Pesavento, J Brad; Uzal, Francisco A

2018-03-05

Carbon monoxide (CO), a common cause of poisoning in human beings has also been implicated in the death of animals. Though there are multiple studies on CO poisoning and relevant lethal blood COHb concentrations in humans, there are no reliable reports of diagnostic lethal carboxyhemoglobin percentage of saturation (COHb%) in cats. Additionally, due to shared housing environments, exposures to companion animals can be a surrogate for lethal exposures in human beings and provide valuable information in concurrent forensic investigations. Two adult Singapura brown ticked cats were submitted to the California Animal Health and Food Safety Laboratory (CAHFS) for necropsy and diagnostic work-up. These animals were found dead along with their two deceased owners. Similar lesions were observed in both cats. At necropsy, gross lesions consisted of multifocal, large, irregular, bright red spots on the skin of the abdomen and the inner surface of ear pinnae, bright red muscles and blood. The carcasses, and tissues fixed in formalin retained the bright red discoloration for up to two weeks. Microscopic lesions included diffuse pulmonary congestion and edema, and multifocal intense basophilia of cardiomyocytes mostly affecting whole fibers or occasionally a portion of the fiber. Based on the clinical history,gross and microscopic changes, cyanide or carbon monoxide poisoning was suspected. Blood samples analyzed for carbon monoxide showed 57 and 41% carboxyhemoglobin COHb%. Muscle samples were negative for cyanide. There are no established reference values for lethal COHb concentration in cats. The COHb % values detected in this case which fell within the lethal range reported for other species, along with the gross lesions and unique histological findings in the heart suggest a helpful criteria for diagnosis of CO intoxication associated death in cats. This case demonstrates that since pets share the same environment as human beings and often are a part of their activities, they can be useful adjuncts in potential forensic investigations to help solve human cases.

Non-24-hour sleep-wake syndrome following a car accident.

PubMed

Boivin, D B; James, F O; Santo, J B; Caliyurt, O; Chalk, C

2003-06-10

The authors report the case of a 39-year-old sighted woman who displayed non-24-hour sleep-wake cycles following a car accident. The phase relationship between endogenous circadian markers such as plasma melatonin and 6-sulfatoxymelatonin rhythms and self-selected sleep times was abnormal. A laboratory investigation indicated that she was sensitive to bright light as a circadian synchronizer. MRI and brain CT scans were normal, but microscopic brain damage in the vicinity of the suprachiasmatic nucleus or its output pathways is plausible.

Microscopic origin of the fast blue-green luminescence of chemically synthesized non-oxidized silicon quantum dots.

PubMed

Dohnalová, Kateřina; Fučíková, Anna; Umesh, Chinnaswamy P; Humpolíčková, Jana; Paulusse, Jos M J; Valenta, Jan; Zuilhof, Han; Hof, Martin; Gregorkiewicz, Tom

2012-10-22

The microscopic origin of the bright nanosecond blue-green photoluminescence (PL), frequently reported for synthesized organically terminated Si quantum dots (Si-QDs), has not been fully resolved, hampering potential applications of this interesting material. Here a comprehensive study of the PL from alkyl-terminated Si-QDs of 2-3 nm size, prepared by wet chemical synthesis is reported. Results obtained on the ensemble and those from the single nano-object level are compared, and they provide conclusive evidence that efficient and tunable emission arises due to radiative recombination of electron-hole pairs confined in the Si-QDs. This understanding paves the way towards applications of chemical synthesis for the development of Si-QDs with tunable sizes and bandgaps. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hunting Faint Dwarf Galaxies in the Field Using Integrated Light Surveys

NASA Astrophysics Data System (ADS)

Danieli, Shany; van Dokkum, Pieter; Conroy, Charlie

2018-03-01

We discuss the approach of searching the lowest mass dwarf galaxies, ≲ {10}6 {M}ȯ , in the general field, using integrated light surveys. By exploring the limiting surface brightness-spatial resolution (μ eff,lim‑θ) parameter space, we suggest that faint field dwarfs in the Local Volume, between 3 and 10 Mpc, are expected to be detected very effectively and in large numbers using integrated light photometric surveys, complementary to the classical star counts method. We use a sample of dwarf galaxies in the Local Group to construct relations between their photometric and structural parameters, M *–μ eff,V and M *–R eff. We use these relations, along with assumed functional forms for the halo mass function and the stellar mass–halo mass (SMHM) relation, to calculate the lowest detectable stellar masses in the Local Volume and the expected number of galaxies as a function of the limiting surface brightness and spatial resolution. The number of detected galaxies depends mostly on the limiting surface brightness for distances >3 Mpc, while spatial resolution starts to play a role for galaxies at distances >8 Mpc. Surveys with μ eff,lim ∼ 30 mag arcsec‑2 should be able to detect galaxies with stellar masses down to ∼104 M ⊙ in the Local Volume. Depending on the form of the SMHM relation, the expected number of dwarf galaxies with distances between 3 and 10 Mpc is 0.04–0.35 per square degree, assuming a limiting surface brightness of ∼29–30 mag arcsec‑2 and a spatial resolution <4″. We plan to search for a population of low-mass dwarf galaxies in the field by performing a blank wide field photometric survey with the Dragonfly Telephoto Array, an imaging system optimized for the detection of extended ultra low surface brightness structures.

Biocompatible near-infrared fluorescent nanoparticles for macro and microscopic in vivo functional bioimaging

PubMed Central

Chu, Liliang; Wang, Shaowei; Li, Kanghui; Xi, Wang; Zhao, Xinyuan; Qian, Jun

2014-01-01

Near-infrared (NIR) imaging technology has been widely used for biomedical research and applications, since it can achieve deep penetration in biological tissues due to less absorption and scattering of NIR light. In our research, polymer nanoparticles with NIR fluorophores doped were synthesized. The morphology, absorption/emission features and chemical stability of the fluorescent nanoparticles were characterized, separately. NIR fluorescent nanoparticles were then utilized as bright optical probes for macro in vivo imaging of mice, including sentinel lymph node (SLN) mapping, as well as distribution and excretion monitoring of nanoparticles in animal body. Furthermore, we applied the NIR fluorescent nanoparticles in in vivo microscopic bioimaging via a confocal microscope. Under the 635 nm-CW excitation, the blood vessel architecture in the ear and the brain of mice, which were administered with nanoparticles, was visualized very clearly. The imaging depth of our one-photon microscopy, which was assisted with NIR fluorescent nanoprobes, can reach as deep as 500 μm. Our experiments show that NIR fluorescent nanoparticles have great potentials in various deep-tissue imaging applications. PMID:25426331

Non-magnetic photospheric bright points in 3D simulations of the solar atmosphere

NASA Astrophysics Data System (ADS)

Calvo, F.; Steiner, O.; Freytag, B.

2016-11-01

Context. Small-scale bright features in the photosphere of the Sun, such as faculae or G-band bright points, appear in connection with small-scale magnetic flux concentrations. Aims: Here we report on a new class of photospheric bright points that are free of magnetic fields. So far, these are visible in numerical simulations only. We explore conditions required for their observational detection. Methods: Numerical radiation (magneto-)hydrodynamic simulations of the near-surface layers of the Sun were carried out. The magnetic field-free simulations show tiny bright points, reminiscent of magnetic bright points, only smaller. A simple toy model for these non-magnetic bright points (nMBPs) was established that serves as a base for the development of an algorithm for their automatic detection. Basic physical properties of 357 detected nMBPs were extracted and statistically evaluated. We produced synthetic intensity maps that mimic observations with various solar telescopes to obtain hints on their detectability. Results: The nMBPs of the simulations show a mean bolometric intensity contrast with respect to their intergranular surroundings of approximately 20%, a size of 60-80 km, and the isosurface of optical depth unity is at their location depressed by 80-100 km. They are caused by swirling downdrafts that provide, by means of the centripetal force, the necessary pressure gradient for the formation of a funnel of reduced mass density that reaches from the subsurface layers into the photosphere. Similar, frequently occurring funnels that do not reach into the photosphere, do not produce bright points. Conclusions: Non-magnetic bright points are the observable manifestation of vertically extending vortices (vortex tubes) in the photosphere. The resolving power of 4-m-class telescopes, such as the DKIST, is needed for an unambiguous detection of them. The movie associated to Fig. 1 is available at http://www.aanda.org

SEM image quality enhancement technology for bright field mask

NASA Astrophysics Data System (ADS)

Fukuda, Naoki; Chihara, Yuta; Shida, Soichi; Ito, Keisuke

2013-09-01

Bright-field photomasks are used to print small contact holes via ArF immersion multiple patterning lithography. There are some technical difficulties when small floating dots are to be measured by SEM tools because of a false imaging shadow. However, a new scan technology of Multi Vision Metrology SEMTM E3630 presents a solution for this issue. The combination of new scan technology and the other MVM-SEM® functions can provide further extended applications with more accurate measurement results.

Portable and cost-effective pixel super-resolution on-chip microscope for telemedicine applications.

PubMed

Bishara, Waheb; Sikora, Uzair; Mudanyali, Onur; Su, Ting-Wei; Yaglidere, Oguzhan; Luckhart, Shirley; Ozcan, Aydogan

2011-01-01

We report a field-portable lensless on-chip microscope with a lateral resolution of <1 μm and a large field-of-view of ~24 mm(2). This microscope is based on digital in-line holography and a pixel super-resolution algorithm to process multiple lensfree holograms and obtain a single high-resolution hologram. In its compact and cost-effective design, we utilize 23 light emitting diodes butt-coupled to 23 multi-mode optical fibers, and a simple optical filter, with no moving parts. Weighing only ~95 grams, we demonstrate the performance of this field-portable microscope by imaging various objects including human malaria parasites in thin blood smears.

A surface science compatible epifluorescence microscope for inspection of samples under ultra high vacuum and cryogenic conditions.

PubMed

Marquardt, Christian; Paulheim, Alexander; Rohbohm, Nils; Merkel, Rudolf; Sokolowski, Moritz

2017-08-01

We modified an epi-illumination light microscope and mounted it on an ultra high vacuum chamber for investigating samples used in a surface science experiment. For easy access and bake out, all optical components are placed outside the vacuum and the sample is imaged through a glass window. The microscope can be operated in reflection brightfield or epifluorescence mode to image the sample surface or fluorescent dye molecules adsorbed on it. The homemade sample mounting was made compatible for the use under the microscope; sample temperatures as low as 6 K can be achieved. The performance of the microscope is demonstrated on two model samples: Brightfield-images of a well-prepared Ag(100) surface show a macroscopic corrugation of the surface, although low energy electron diffraction data indicate a highly ordered crystalline surface. The surface shows macroscopic protrusions with flat regions, about 20-200 μm in diameter, in between. Fluorescence images of diluted 3,4,9,10-perylene tetracarboxylicacid dianhydride (PTCDA) molecules adsorbed on an ultrathin epitaxial KCl film on the Ag(100) surface show a shading effect at surface protrusions due to an inclined angle of incidence of the PTCDA beam during deposition. For some preparations, the distribution of the fluorescence intensity is inhomogeneous and shows a dense network of bright patches about 5 μm in diameter related to the macroscopic corrugation of the surface. We propose that such a light microscope can aid many surface science experiments, especially those dealing with epitaxial growth or fluorescent materials.

Statics and dynamics of atomic dark-bright solitons in the presence of impurities

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

Achilleos, V.; Frantzeskakis, D. J.; Kevrekidis, P. G.

2011-11-15

Adopting a mean-field description for a two-component atomic Bose-Einstein condensate, we study the statics and dynamics of dark-bright solitons in the presence of localized impurities. We use adiabatic perturbation theory to derive an equation of motion for the dark-bright soliton center. We show that, counterintuitively, an attractive (repulsive) delta-like impurity, acting solely on the bright-soliton component, induces an effective localized barrier (well) in the effective potential felt by the soliton; this way, dark-bright solitons are reflected from (transmitted through) attractive (repulsive) impurities. Our analytical results for the small-amplitude oscillations of solitons are found to be in good agreement with resultsmore » obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.« less

The X-ray microscopy beamline UE46-PGM2 at BESSY

NASA Astrophysics Data System (ADS)

Follath, R.; Schmidt, J. S.; Weigand, M.; Fauth, K.

2010-06-01

The Max Planck Institute for Metal Physics in Stuttgart and the Helmholtz Center Berlin operate a soft X-ray microscopy beamline at the storage ring BESSY II. A collimated PGM serves as monochromator for a scanning X-ray microscope and a full field X-ray microscope at the helical undulator UE46. The selection between both instruments is accomplished via two switchable focusing mirrors. The scanning microscope (SM) is based on the ALS STXM microscope and fabricated by the ACCEL company. The full field microscope (FFM) is currently in operation at the U41-SGM beamline and will be relocated to its final location this year.

Label-free nanoscale characterization of red blood cell structure and dynamics using single-shot transport of intensity equation

NASA Astrophysics Data System (ADS)

Poola, Praveen Kumar; John, Renu

2017-10-01

We report the results of characterization of red blood cell (RBC) structure and its dynamics with nanometric sensitivity using transport of intensity equation microscopy (TIEM). Conventional transport of intensity technique requires three intensity images and hence is not suitable for studying real-time dynamics of live biological samples. However, assuming the sample to be homogeneous, phase retrieval using transport of intensity equation has been demonstrated with single defocused measurement with x-rays. We adopt this technique for quantitative phase light microscopy of homogenous cells like RBCs. The main merits of this technique are its simplicity, cost-effectiveness, and ease of implementation on a conventional microscope. The phase information can be easily merged with regular bright-field and fluorescence images to provide multidimensional (three-dimensional spatial and temporal) information without any extra complexity in the setup. The phase measurement from the TIEM has been characterized using polymeric microbeads and the noise stability of the system has been analyzed. We explore the structure and real-time dynamics of RBCs and the subdomain membrane fluctuations using this technique.

Sources of Emittance in RF Photocathode Injectors

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

Dowell, David

2016-12-11

Advances in electron beam technology have been central to creating the current generation of x-ray free electron lasers and ultra-fast electron microscopes. These once exotic devices have become essential tools for basic research and applied science. One important beam technology for both is the electron source which, for many of these instruments, is the photocathode RF gun. The invention of the photocathode gun and the concepts of emittance compensation and beam matching in the presence of space charge and RF forces have made these high-quality beams possible. Achieving even brighter beams requires a taking a finer resolution view of themore » electron dynamics near the cathode during photoemission and the initial acceleration of the beam. In addition, the high brightness beam is more sensitive to degradation by the optical aberrations of the gun’s RF and magnetic lenses. This paper discusses these topics including the beam properties due to fundamental photoemission physics, space charge effects close to the cathode, and optical distortions introduced by the RF and solenoid fields. Analytic relations for these phenomena are derived and compared with numerical simulations.« less

[Urinalysis in Italy in 2006].

PubMed

Gai, M; Lanfranco, G

2007-01-01

Urinalysis and proteinuria testing represent fundamental tests for the clinician, even though they too often lack standardization. Through the Italian Society of Nephrology Mailing List we sent a questionnaire to 282 centers, in order to assess the state of the art in Italy in the year 2006. 82% of the questionnaires were completed (nephrology laboratories: 64%, general laboratories: 36%). The questionnaire dealt with the main steps of preparation, analysis and report of urinalysis, and proteinuria / microalbuminuria measurement. 85% of the centers use first morning urine, and 7% second morning urine; only 57% of the centers supply with written instructions, 189 laboratories (82%) have only one bright field microscope, rate and time of centrifugation are very varied among centers, different units of measurement are used in reports. Few laboratories measure routinely the proteinuria / creatininuria ratio, there is no agreement on the urine sample type for microalbuminuria assay, total urinary proteins are measured through different methods. 92% of the centers is endowed with an internal quality control system, but only 47% participate in an external quality control program. These data confirm the lack of standardization for urine analysis methods and procedures.

Dissecting Diffuse X-ray Emission in 30 Doradus with T-ReX

NASA Astrophysics Data System (ADS)

Townsley, Leisa K.; Broos, Patrick

2017-08-01

30 Doradus (the Tarantula Nebula) offers us a microscope on starburst astrophysics, having endured 25 Myrs of the birth and death of the most massive stars known. Across 30 Dor's 250-pc extent, stellar winds and supernovae have carved its ISM into an amazing display of arcs, pillars, and bubbles. For over 40 years, we have also known that 30 Dor is a bright X-ray emitter, so its familiar stars and cold ISM structures suffer irradiation by multi-million-degree plasmas. The 2-Ms Chandra X-ray Visionary Project ``The Tarantula -- Revealed by X-rays'' (T-ReX) exploits Chandra's fine spatial resolution and the ACIS-I field of view to study ISM interfaces on 1--10 pc scales across the entire 30 Dor complex. Here we give preliminary results from ongoing analyses of these data, focusing on the diffuse X-ray emission. Massive star winds and cavity supernovae over the millenia have contributed to a broad mix of X-ray-emitting plasmas and absorbing columns, showing that 30 Dor's hot ISM is just as complex and confusing as that seen at colder temperatures.

L band brightness temperature observations over a corn canopy during the entire growth cycle

USDA-ARS?s Scientific Manuscript database

During a field campaign covering the 2002 corn growing season, a dual polarized tower mounted L-band (1.4 GHz) radiometer (LRAD) provided brightness temperature (T¬B) measurements at preset intervals, incidence and azimuth angles. These radiometer measurements were supported by an extensive characte...

50 CFR 32.59 - Rhode Island.

Code of Federal Regulations, 2013 CFR

2013-10-01

... to, the use of flagging, bright eyes, tacks, and paint), cutting, and/or removal of trees or.... We prohibit hunters field dressing deer within 100 feet (30 m) of a road or trail. 22. We prohibit... to, the use of flagging, bright eyes, tacks, and paint), cutting, and/or removal of trees or...

50 CFR 32.59 - Rhode Island.

Code of Federal Regulations, 2014 CFR

2014-10-01

... to, the use of flagging, bright eyes, tacks, and paint), cutting, and/or removal of trees or.... We prohibit hunters field dressing deer within 100 feet (30 m) of a road or trail. 22. We prohibit... to, the use of flagging, bright eyes, tacks, and paint), cutting, and/or removal of trees or...

50 CFR 32.59 - Rhode Island.

Code of Federal Regulations, 2012 CFR

2012-10-01

... to, the use of flagging, bright eyes, tacks, and paint), cutting, and/or removal of trees or.... We prohibit hunters field dressing deer within 100 feet (30 m) of a road or trail. 22. We prohibit... to, the use of flagging, bright eyes, tacks, and paint), cutting, and/or removal of trees or...

On Heating Large Bright Coronal Loops by Magnetic Microexplosions at their Feet

NASA Technical Reports Server (NTRS)

Moore, Ronald L; Falconer, D. A.; Porter, Jason G.

1999-01-01

In previous work, by registering Yohkoh SXT coronal X-ray images with MSFC vector magnetograms, we found that: (1) many of the larger bright coronal loops rooted at one or both ends in an active region are rooted around magnetic islands of included polarity, (2) the core field encasing the neutral line encircling the island is strongly sheared, and (3) this sheared core field is the seat of frequent microflares. This suggests that the coronal heating in these extended bright loops is driven by many small explosive releases of stored magnetic energy from the sheared core field at their feet, some of which magnetic microexplosions also produce the microflare heating in the core fields. In this paper, we show that this scenario is feasible in terms of the energy Abstract: required for the observed coronal heating and the magnetic energy available in the observed sheared core fields. In a representative active region, from the X-ray and vector field data, we estimate the coronal heating consumption by a selected typical large bright loop, the coronal heating consumption by a typical microflare at the foot of this loop, the frequency of microflares at the foot, and the available magnetic energy in the microflaring core field. We find that: (1) the rate of magnetic energy release to power the microflares at the foot (approx. 6 x 10(ext 25)erg/s) is enough to also power the coronal heating in the body of the extended loop (approx. 2 x l0(exp 25 erg/s), and (2) there is enough stored magnetic energy in the sheared core field to sustain the microflaring and extended loop heating for about a day, which is a typical time for buildup of neutral-line magnetic shear in an active region. This work was funded by the Solar Physics Branch of NASA's Office of Space Science through the SR&T Program and the SEC Guest Investigator Program.

Behavior of Solar Cycles 23 and 24 Revealed by Microwave Observations

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Yashiro, S.; Maekelae, P.; Michalek, G.; Shibasaki, K.; Hathaway, D. H.

2012-01-01

Using magnetic and microwave butterfly diagrams, we compare the behavior of solar polar regions to show that (1) the polar magnetic field and the microwave brightness temperature during solar minimum substantially diminished during the cycle 23/24 minimum compared to the 22/23 minimum. (2) The polar microwave brightness temperature (Tb) seems to be a good proxy for the underlying magnetic field strength (B). The analysis indicates a relationship, B = 0.0067Tb - 70, where B is in G and Tb in K. (3) Both the brightness temperature and the magnetic field strength show north-south asymmetry most of the time except for a short period during the maximum phase. (4) The rush-to-the-pole phenomenon observed in the prominence eruption (PE) activity seems to be complete in the northern hemisphere as of 2012 March. (5) The decline of the microwave brightness temperature in the north polar region to the quiet-Sun levels and the sustained PE activity poleward of 60degN suggest that solar maximum conditions have arrived at the northern hemisphere. The southern hemisphere continues to exhibit conditions corresponding to the rise phase of solar cycle 24. Key words: Sun: chromosphere Sun: coronal mass ejections (CMEs) Sun: filaments, prominences Sun: photosphere Sun: radio radiation Sun: surface magnetism

The Optical Gravitational Lensing Experiment: Red Clump Stars as a Distance Indicator.

PubMed

Udalski

2000-03-01

We present relation of the mean I-band brightness of red clump stars on metallicity. Red clump stars were proposed to be a very attractive standard candle for distance determination. The calibration is based on 284 nearby red giant stars whose high-quality spectra made it possible to determine accurate individual metal abundances. High-quality parallaxes (sigmapi&solm0;pi<10%) and photometry of these very bright stars come from Hipparcos measurements. Metallicity of the sample covers a large range: -0.6 dex<&sqbl0;Fe&solm0;H&sqbr0;<+0.2 dex. We find a weak dependence of the mean I-band brightness on metallicity ( approximately 0.13 mag dex-1). What is more important, the range of metallicity of the Hipparcos sample partially overlaps with metallicity of field giants in the LMC, thus making it possible to determine the distance to the LMC by almost direct comparison of brightness of the local Hipparcos red clump giants with that of LMC stars. Photometry of field red clump giants in nine low-extinction fields of the LMC halo collected during the OGLE II microlensing survey compared with the Hipparcos red clump stars data yields the distance modulus to the LMC: &parl0;m-M&parr0;LMC=18.24+/-0.08 mag.

35 GHz Measurements of CO2 Crystals for Simulating Observations of the Martian Polar Caps

NASA Technical Reports Server (NTRS)

Foster, J. L.; Chang, A. T. C.; Hall, D. K.; Tait, A. B.; Barton, J. S.

1998-01-01

In order to learn more about the Martian polar caps, it is important to compare and contrast the behavior of both frozen H2O and CO2 in different parts of the electromagnetic spectrum. Relatively little attention has been given, thus far, to observing the thermal microwave part of the spectrum. In this experiment, passive microwave radiation emanating from within a 33 cm snowpack was measured with a 35 GHz hand-held radiometer, and in addition to the natural snow measurements, the radiometer was used to measure the microwave emission and scattering from layers of manufactured CO2 (dry ice). A 1 m x 2 m plate of aluminum sheet metal was positioned beneath the natural snow so that microwave emissions from the underlying soil layers would be minimized. Compared to the natural snow crystals, results for the dry ice layers exhibit lower' microwave brightness temperatures for similar thicknesses, regardless of the incidence angle of the radiometer. For example, at 50 degree H (horizontal polarization) and with a covering of 21 cm of snow and 18 cm of dry ice, the brightness temperatures were 150 K and 76 K, respectively. When the snow depth was 33 cm, the brightness temperature was 144 K, and when the total thickness of the dry ice was 27 cm, the brightness temperature was 86 K. The lower brightness temperatures are due to a combination of the lower physical temperature and the larger crystal sizes of the commercial CO2 Crystals compared to the snow crystals. As the crystal size approaches the size of the microwave wavelength, it scatters microwave radiation more effectively, thus lowering the brightness temperature. The dry ice crystals in this experiment were about an order of magnitude larger than the snow crystals and three orders of magnitude larger than the CO2 Crystals produced in the cold stage of a scanning electron microscope. Spreading soil, approximately 2 mm in thickness, on the dry ice appeared to have no effect on the brightness temperatures.

Magnetic annihilation of the dark mode in a strongly coupled bright-dark terahertz metamaterial.

PubMed

Manjappa, Manukumara; Turaga, Shuvan Prashant; Srivastava, Yogesh Kumar; Bettiol, Andrew Anthony; Singh, Ranjan

2017-06-01

Dark mode in metamaterials has become a vital component in determining the merit of the Fano type of interference in the system. Its strength dictates the enhancement and suppression in the amplitude and Q-factors of resulting resonance features. In this work, we experimentally probe the effect of strong near-field coupling on the strength of the dark mode in a concentrically aligned bright resonator and a dark split ring resonator (SRR) system exhibiting the classical analog of the electromagnetically induced transparency effect. An enhanced strong magnetic field between the bright-dark resonators destructively interferes with the inherent magnetic field of the dark mode to completely annihilate its effect in the coupled system. Moreover, the observed annihilation effect in the dark mode has a direct consequence on the disappearance of the SRR effect in the proposed system, wherein under the strong magnetic interactions, the LC resonance feature of the split ring resonator becomes invisible to the incident terahertz wave.

Use of fluorescence and scanning electron microscopy as tools in teaching biology

NASA Astrophysics Data System (ADS)

Ghosh, Nabarun; Silva, Jessica; Vazquez, Aracely; Das, A. B.; Smith, Don W.

2011-06-01

Recent nationwide surveys reveal significant decline in students' interest in Math and Sciences. The objective of this project was to inspire young minds in using various techniques involved in Sciences including Scanning Electron Microscopy. We used Scanning Electron Microscope in demonstrating various types of Biological samples. An SEM Tabletop model in the past decade has revolutionized the use of Scanning Electron Microscopes. Using SEM Tabletop model TM 1000 we studied biological specimens of fungal spores, pollen grains, diatoms, plant fibers, dust mites, insect parts and leaf surfaces. We also used fluorescence microscopy to view, to record and analyze various specimens with an Olympus BX40 microscope equipped with FITC and TRITC fluorescent filters, a mercury lamp source, DP-70 digital camera with Image Pro 6.0 software. Micrographs were captured using bright field microscopy, the fluoresceinisothiocyanate (FITC) filter, and the tetramethylrhodamine (TRITC) filter settings at 40X. A high pressure mercury lamp or UV source was used to excite the storage molecules or proteins which exhibited autofluorescence. We used fluorescent microscopy to confirm the localization of sugar beet viruses in plant organs by viewing the vascular bundles in the thin sections of the leaves and other tissues. We worked with the REU summer students on sample preparation and observation on various samples utilizing the SEM. Critical Point Drying (CPD) and metal coating with the sputter coater was followed before observing some cultured specimen and the samples that were soft in textures with high water content. SEM Top allowed investigating the detailed morphological features that can be used for classroom teaching. Undergraduate and graduate researchers studied biological samples of Arthropods, pollen grains and teeth collected from four species of snakes using SEM. This project inspired the research students to pursue their career in higher studies in science and 45% of the undergraduates participated in this project entered Graduate school.

Winter sky brightness & cloud cover over Dome A

NASA Astrophysics Data System (ADS)

Yang, Yi; Moore, A. M.; Fu, J.; Ashley, M.; Cui, X.; Feng, L.; Gong, X.; Hu, Z.; Laurence, J.; LuongVan, D.; Riddle, R. L.; Shang, Z.; Sims, G.; Storey, J.; Tothill, N.; Travouillon, T.; Wang, L.; Yang, H.; Yang, J.; Zhou, X.; Zhu, Z.; Burton, M. G.

2014-01-01

At the summit of the Antarctic plateau, Dome A offers an intriguing location for future large scale optical astronomical Observatories. The Gattini DomeA project was created to measure the optical sky brightness and large area cloud cover of the winter-time sky above this high altitude Antarctic site. The wide field camera and multi-filter system was installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in January 2008. This automated wide field camera consists of an Apogee U4000 interline CCD coupled to a Nikon fish-eye lens enclosed in a heated container with glass window. The system contains a filter mechanism providing a suite of standard astronomical photometric filters (Bessell B, V, R), however, the absence of tracking systems, together with the ultra large field of view 85 degrees) and strong distortion have driven us to seek a unique way to build our data reduction pipeline. We present here the first measurements of sky brightness in the photometric B, V, and R band, cloud cover statistics measured during the 2009 winter season and an estimate of the transparency. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based location. A ~0.2 magnitude agreement of our simultaneous test at Palomar Observatory with NSBM(National Sky Brightness Monitor), as well as an 0.04 magnitude photometric accuracy for typical 6th magnitude stars limited by the instrument design, indicating we obtained reasonable results based on our ~7mm effective aperture fish-eye lens.

Optical Sky Brightness and Transparency during the Winter Season at Dome A Antarctica from the Gattini-All-Sky Camera

NASA Astrophysics Data System (ADS)

Yang, Yi; Moore, Anna M.; Krisciunas, Kevin; Wang, Lifan; Ashley, Michael C. B.; Fu, Jianning; Brown, Peter J.; Cui, Xiangqun; Feng, Long-Long; Gong, Xuefei; Hu, Zhongwen; Lawrence, Jon S.; Luong-Van, Daniel; Riddle, Reed L.; Shang, Zhaohui; Sims, Geoff; Storey, John W. V.; Suntzeff, Nicholas B.; Tothill, Nick; Travouillon, Tony; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhenxi

2017-07-01

The summit of the Antarctic plateau, Dome A, is proving to be an excellent site for optical, near-infrared, and terahertz astronomical observations. Gattini is a wide-field camera installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in 2009 January. We present here the measurements of sky brightness with the Gattini ultra-large field of view (90^\\circ × 90^\\circ ) in the photometric B-, V-, and R-bands; cloud cover statistics measured during the 2009 winter season; and an estimate of the sky transparency. A cumulative probability distribution indicates that the darkest 10% of the nights at Dome A have sky brightness of S B = 22.98, S V = 21.86, and S R = 21.68 mag arcsec-2. These values were obtained during the year 2009 with minimum aurora, and they are comparable to the faintest sky brightness at Maunakea and the best sites of northern Chile. Since every filter includes strong auroral lines that effectively contaminate the sky brightness measurements, for instruments working around the auroral lines, either with custom filters or with high spectral resolution instruments, these values could be easily obtained on a more routine basis. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based site. These light curves will be published in a future paper.

Lunar and Venusian radar bright rings

NASA Technical Reports Server (NTRS)

Thompson, T. W.; Saunders, R. S.; Weissman, D. E.

1986-01-01

Twenty-one lunar craters have radar bright ring appearances which are analogous to eleven complete ring features in the earth-based 12.5 cm observations of Venus. Radar ring diameters and widths for the lunar and Venusian features overlap for sizes from 45 to 100 km. Radar bright areas for the lunar craters are associated with the slopes of the inner and outer rim walls, while level crater floors and level ejecta fields beyond the raised portion of the rim have average radar backscatter. It is proposed that the radar bright areas of the Venusian rings are also associated with the slopes on the rims of craters. The lunar craters have evolved to radar bright rings via mass wasting of crater rim walls and via post-impact flooding of crater floors. Aeolian deposits of fine-grained material on Venusian crater floors may produce radar scattering effects similar to lunar crater floor flooding. These Venusian aeolian deposits may preferentially cover blocky crater floors producing a radar bright ring appearance. It is proposed that the Venusian features with complete bright ring appearances and sizes less than 100 km are impact craters. They have the same sizes as lunar craters and could have evolved to radar bright rings via analogous surface processes.

Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

NASA Astrophysics Data System (ADS)

Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Sabri, Nor Hazmin; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

2017-03-01

Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

Subjective figures and texture perception.

PubMed

Zucker, S W; Cavanagh, P

1985-01-01

A texture discrimination task using the Ehrenstein illusion demonstrates that subjective brightness effects can play an essential role in early vision. The subjectively bright regions of the Ehrenstein can be organized either as discs or as stripes, depending on orientation. The accuracy of discrimination between variants of the Ehrenstein and control patterns was a direct function of the presence of the illusory brightness stripes, being high when they were present and low otherwise. It is argued that neither receptive field structure nor spatial-frequency content can adequately account for these results. We suggest that the subjective brightness illusions, rather than being a high-level, cognitive aspect of vision, are in fact the result of an early visual process.

A dark-field microscope for background-free detection of resonance fluorescence from single semiconductor quantum dots operating in a set-and-forget mode

NASA Astrophysics Data System (ADS)

Kuhlmann, Andreas V.; Houel, Julien; Brunner, Daniel; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.; Warburton, Richard J.

2013-07-01

Optically active quantum dots, for instance self-assembled InGaAs quantum dots, are potentially excellent single photon sources. The fidelity of the single photons is much improved using resonant rather than non-resonant excitation. With resonant excitation, the challenge is to distinguish between resonance fluorescence and scattered laser light. We have met this challenge by creating a polarization-based dark-field microscope to measure the resonance fluorescence from a single quantum dot at low temperature. We achieve a suppression of the scattered laser exceeding a factor of 107 and background-free detection of resonance fluorescence. The same optical setup operates over the entire quantum dot emission range (920-980 nm) and also in high magnetic fields. The major development is the outstanding long-term stability: once the dark-field point has been established, the microscope operates for days without alignment. The mechanical and optical designs of the microscope are presented, as well as exemplary resonance fluorescence spectroscopy results on individual quantum dots to underline the microscope's excellent performance.

Zernike analysis of all-sky night brightness maps.

PubMed

Bará, Salvador; Nievas, Miguel; Sánchez de Miguel, Alejandro; Zamorano, Jaime

2014-04-20

All-sky night brightness maps (calibrated images of the night sky with hemispherical field-of-view (FOV) taken at standard photometric bands) provide useful data to assess the light pollution levels at any ground site. We show that these maps can be efficiently described and analyzed using Zernike circle polynomials. The relevant image information can be compressed into a low-dimensional coefficients vector, giving an analytical expression for the sky brightness and alleviating the effects of noise. Moreover, the Zernike expansions allow us to quantify in a straightforward way the average and zenithal sky brightness and its variation across the FOV, providing a convenient framework to study the time course of these magnitudes. We apply this framework to analyze the results of a one-year campaign of night sky brightness measurements made at the UCM observatory in Madrid.

Scanning electron microscope automatic defect classification of process induced defects

NASA Astrophysics Data System (ADS)

Wolfe, Scott; McGarvey, Steve

2017-03-01

With the integration of high speed Scanning Electron Microscope (SEM) based Automated Defect Redetection (ADR) in both high volume semiconductor manufacturing and Research and Development (R and D), the need for reliable SEM Automated Defect Classification (ADC) has grown tremendously in the past few years. In many high volume manufacturing facilities and R and D operations, defect inspection is performed on EBeam (EB), Bright Field (BF) or Dark Field (DF) defect inspection equipment. A comma separated value (CSV) file is created by both the patterned and non-patterned defect inspection tools. The defect inspection result file contains a list of the inspection anomalies detected during the inspection tools' examination of each structure, or the examination of an entire wafers surface for non-patterned applications. This file is imported into the Defect Review Scanning Electron Microscope (DRSEM). Following the defect inspection result file import, the DRSEM automatically moves the wafer to each defect coordinate and performs ADR. During ADR the DRSEM operates in a reference mode, capturing a SEM image at the exact position of the anomalies coordinates and capturing a SEM image of a reference location in the center of the wafer. A Defect reference image is created based on the Reference image minus the Defect image. The exact coordinates of the defect is calculated based on the calculated defect position and the anomalies stage coordinate calculated when the high magnification SEM defect image is captured. The captured SEM image is processed through either DRSEM ADC binning, exporting to a Yield Analysis System (YAS), or a combination of both. Process Engineers, Yield Analysis Engineers or Failure Analysis Engineers will manually review the captured images to insure that either the YAS defect binning is accurately classifying the defects or that the DRSEM defect binning is accurately classifying the defects. This paper is an exploration of the feasibility of the utilization of a Hitachi RS4000 Defect Review SEM to perform Automatic Defect Classification with the objective of the total automated classification accuracy being greater than human based defect classification binning when the defects do not require multiple process step knowledge for accurate classification. The implementation of DRSEM ADC has the potential to improve the response time between defect detection and defect classification. Faster defect classification will allow for rapid response to yield anomalies that will ultimately reduce the wafer and/or the die yield.

Pinacate-gran Desierto Region, Mexico: SIR-A Data Analysis

NASA Technical Reports Server (NTRS)

Christensen, P.; Greeley, R.; Mchone, J.; Asmerom, Y.; Barnett, S.

1984-01-01

Radar images (SIR-A) from the Columbia space shuttle were used to assess the radar returns of terrain shaped by volcanic, aeolian, and fluvial processes in northwest Sonora. Field studies and photointerpretation show that sand dunes are poorly imaged by SIR-A, in contrast to SEASAT, evidently a consequence of the greater SIR-A incidence angle; star dunes are visible only as small bright spots representing merging arms at dune apices which may act as corner reflectors. Desert grasses and bushes (approx. 2 m high) have little effect on radar brightness. Only larger trees with woody trunks approx. 0.5 m across are effective radar reflectors; their presence contributes to radar bright zones along some arroyos. The radar brightness of lava flows decreases with surface roughness and presence of mantling windblown sediments and weathering products; however, old uplifted (faulted) flows are of equal brightness to fresh, unmantled aa flows. Maar craters display circular patterns of varying radar brightness which represent a combination of geometry, slope, and distribution of surface materials. Some radar bright rings in the Pinacates resemble craters on radar but are observed to be playas encircled by trees.

Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile

NASA Astrophysics Data System (ADS)

Gilbert, Karoline M.; Guhathakurta, Puragra; Beaton, Rachael L.; Bullock, James; Geha, Marla C.; Kalirai, Jason S.; Kirby, Evan N.; Majewski, Steven R.; Ostheimer, James C.; Patterson, Richard J.; Tollerud, Erik J.; Tanaka, Mikito; Chiba, Masashi

2012-11-01

We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnostics is used to identify and reject foreground and background contaminants. This enables us to trace the stellar halo of M31 to larger projected distances and fainter surface brightnesses than previous photometric studies. The surface brightness profile of M31's halo follows a power law with index -2.2 ± 0.2 and extends to a projected distance of at least ~175 kpc (~2/3 of M31's virial radius), with no evidence of a downward break at large radii. The best-fit elliptical isophotes have b/a = 0.94 with the major axis of the halo aligned along the minor axis of M31's disk, consistent with a prolate halo, although the data are also consistent with M31's halo having spherical symmetry. The fact that tidal debris features are kinematically cold is used to identify substructure in the spectroscopic fields out to projected radii of 90 kpc and investigate the effect of this substructure on the surface brightness profile. The scatter in the surface brightness profile is reduced when kinematically identified tidal debris features in M31 are statistically subtracted; the remaining profile indicates that a comparatively diffuse stellar component to M31's stellar halo exists to large distances. Beyond 90 kpc, kinematically cold tidal debris features cannot be identified due to small number statistics; nevertheless, the significant field-to-field variation in surface brightness beyond 90 kpc suggests that the outermost region of M31's halo is also comprised to a significant degree of stars stripped from accreted objects. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Influence of interplanetary magnetic field and solar wind on auroral brightness in different regions

NASA Astrophysics Data System (ADS)

Yang, Y. F.; Lu, J. Y.; Wang, J.-S.; Peng, Z.; Zhou, L.

2013-01-01