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Sample records for linear slit scanning

  1. An explanation for the extremely low, but variable, radiation dosages measured in a linear slit scanning radiography system

    NASA Astrophysics Data System (ADS)

    Potgieter, J. H.; de Villiers, Mattieu; Scheelke, Martin; de Jager, Gerhard

    2005-04-01

    Clinical trials performed for the FDA"s Section 510k compliance submission of the Statscan digital, full-body, linear slit scanning diagnostic radiography system revealed that comparable diagnostic results with a commercial full-field screen film device were obtained with the Statscan using much lower radiation doses. For certain imaging procedures the doses for Statscan were as much as twenty to thirty times lower. However the results varied by a large amount and in particular the results for chest radiographs were anomalous in that the Statscan dose was less reduced. Whilst it is well known that slit scanning radiography has considerably lower radiation exposure than full-field devices due to its much lower scatter to primary ratio and also that digital radiography has the potential for lower radiation dosages, it was thought that that this alone did not fully account for the dose differences. This paper suggests that these dose differences, including the anomaly mentioned above, can be explained by considering the unique way that slit scanning is undertaken by Statscan i.e. by scanning the tube, detector, slit and collimators together along a linear path. The effect on measured skin entrance doses is explained and the dosage differences as affected by digital technology, higher DQE, slit scanning (low scatter to primary ratio) and linear slit scanning methods are quantified. Furthermore it is explained how the Statscan geometry leads an improved "skin sparing" effect.

  2. Developing scanning-slit spectrograph for imaging the Sun

    NASA Astrophysics Data System (ADS)

    Pruthvi, Hemanth; Ramesh, K. B.; Dhara, Sajal Kumar; Ravindra, B.

    2016-08-01

    For moderate resolution spectroscopy of the Sun, an imaging spectrograph is being developed at Indian Institute of Astrophysics. With this instrument images of the region of interest of the Sun can be obtained with low spatial and moderate spectral resolution. Dopplergrams can also be obtained with the acquired data to get line of sight velocity maps. The instrument is a back-end for a telescope with tracking system i.e. stable image of the Sun is projected onto the focal plane at all times. Modular approach is followed in the design, keeping sections of the instruments fairly independent. Scanning-slit assembly is a module that can linearly move in one direction to sweep the region of interest in the image. Spectrograph assembly consists of another slit, optics and dispersing element along with the detector so that spectral information about spatial locations on the slit can be obtained. This module is designed to obtain Intensity vs. (x,λ) (x is along the slit) and as the scanning-slit is swept along the y-direction, Intensity vs. (x,y,λ) information is built. The spatial resolution will be seeing limited as there's no correction system. Field of view is 6 arc minute along the slit direction, as the features of interest include sunspots and surrounding region. For testing, a front end system of 100mm clear aperture with f/22.5 is being used. The dispersing element is a reflecting grating with 1200 grooves/mm. For 6563 Å(H-alpha line) spectral resolution is 35 mÅ in second order. Linear dispersion is about 38 mÅ /pixel for the pixel size of 7.5μm, indicating that slit-width limited spectral resolution can be obtained.

  3. Slit-enabled linear-array photoacoustic tomography with near isotropic spatial resolution in three dimensions

    PubMed Central

    Wang, Yuehang; Wang, Depeng; Zhang, Yumiao; Geng, Jumin; Lovell, Jonathan F.; Xia, Jun

    2016-01-01

    Due to its unique capability of visualizing optical absorption in deep tissues, photoacoustic tomography is increasingly used in biomedical imaging. Among various types of transducer arrays, the linear array is perhaps the most widely used in photoacoustic tomography, because it is commercially available and readily allows ultrasound imaging. However, the three-dimensional imaging capability of a linear array is limited, due to its poor elevational resolution. While various scanning schemes have been proposed to address this problem, they all suffer from long scanning time. To address this issue, we introduce slit-enabled three-dimensional photoacoustic tomography. The metal slit, placed at the array focus, causes the incoming photoacoustic waves to diffract along the elevation direction and hence significantly improves the elevation detection aperture and resolution. We tested the new system in both phantoms and animals. The slit improves the elevation resolution by ten times without compromising scanning time. PMID:26696175

  4. Non-linear Young's double-slit experiment.

    PubMed

    San Roman, Julio; Ruiz, Camilo; Perez, Jose Antonio; Delgado, Diego; Mendez, Cruz; Plaja, Luis; Roso, Luis

    2006-04-03

    The Young's double slit experiment is recreated using intense and short laser pulses. Our experiment evidences the role of the non-linear Kerr effect in the formation of interference patterns. In particular, our results evidence a mixed mechanism in which the zeroth diffraction order of each slit are mainly affected by self-focusing and self-phase modulation, while the higher orders propagate linearly. Despite of the complexity of the general problem of non-linear propagation, we demonstrate that this experiment retains its simplicity and allows for a geometrical interpretation in terms of simple optical paths. In consequence, our results may provide key ideas on experiments on the formation of interference patterns with intense laser fields in Kerr media.

  5. Parameter estimation for slit-type scanning sensors

    NASA Technical Reports Server (NTRS)

    Fowler, J. W.; Rolfe, E. G.

    1981-01-01

    The Infrared Astronomical Satellite, scheduled for launch into a 900 km near-polar orbit in August 1982, will perform an infrared point source survey by scanning the sky with slit-type sensors. The description of position information is shown to require the use of a non-Gaussian random variable. Methods are described for deciding whether separate detections stem from a single common source, and a formulism is developed for the scan-to-scan problems of identifying multiple sightings of inertially fixed point sources for combining their individual measurements into a refined estimate. Several cases are given where the general theory yields results which are quite different from the corresponding Gaussian applications, showing that argument by Gaussian analogy would lead to error.

  6. Parameter estimation for slit-type scanning sensors

    NASA Technical Reports Server (NTRS)

    Fowler, J. W.; Rolfe, E. G.

    1981-01-01

    The Infrared Astronomical Satellite, scheduled for launch into a 900 km near-polar orbit in August 1982, will perform an infrared point source survey by scanning the sky with slit-type sensors. The description of position information is shown to require the use of a non-Gaussian random variable. Methods are described for deciding whether separate detections stem from a single common source, and a formulism is developed for the scan-to-scan problems of identifying multiple sightings of inertially fixed point sources for combining their individual measurements into a refined estimate. Several cases are given where the general theory yields results which are quite different from the corresponding Gaussian applications, showing that argument by Gaussian analogy would lead to error.

  7. Improved Miniaturized Linear Ion Trap Mass Spectrometer Using Lithographically Patterned Plates and Tapered Ejection Slit

    NASA Astrophysics Data System (ADS)

    Tian, Yuan; Decker, Trevor K.; McClellan, Joshua S.; Bennett, Linsey; Li, Ailin; De la Cruz, Abraham; Andrews, Derek; Lammert, Stephen A.; Hawkins, Aaron R.; Austin, Daniel E.

    2017-08-01

    We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM). [Figure not available: see fulltext.

  8. Improved Miniaturized Linear Ion Trap Mass Spectrometer Using Lithographically Patterned Plates and Tapered Ejection Slit.

    PubMed

    Tian, Yuan; Decker, Trevor K; McClellan, Joshua S; Bennett, Linsey; Li, Ailin; De la Cruz, Abraham; Andrews, Derek; Lammert, Stephen A; Hawkins, Aaron R; Austin, Daniel E

    2017-08-23

    We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM). Graphical Abstract ᅟ.

  9. Centromeric index measurement by slit-scan flow cytometry

    SciTech Connect

    Lucas, J.N.; Gray, J.W.; Peters, D.C.; Van Dilla, M.A.

    1983-01-01

    A report is given of the application of slit-scan flow cytometry (SSFCM) in the classification of muntjac, Chinese hamster, and human chromosomes according to centromeric index (CI) and total fluorescence. Chromosomes were isolated from mitotic cells, stained with propidium iodide and processed through the SSFCM where fluorescence profiles were measured. The centromere for each profile was taken as the point of maximum difference between the measured profile and a standard profile having no centromeric dip. The areas under the profile on either side of the centromere were then calculated and the CI was calculated as the ratio of the larger area to the total area under the profile. Relative DNA contents for each chromosome were taken to be proportional to the total fluorescence. Mean CI's for muntjac chromosomes 1, 2, and X + 3 were 0.52, 0.88, and 0.73, respectively; CI's for Chinese hamster M3-1 chromosomes 1, 2, 5, 8, and M2 were 0.53, 0.55, 0.57, 0.77, and 0.86, respectively; and average CI's for chromosome groups 4 + t (X;5), 6 + 7 + Y, 9 + M1, and 10 + 11 were 0.56, 0.82, 0.58, and 0.60, respectively. These results were, on average, within 4.4% of CI measurements made by image cytometry. CI's measured for human chromosomes 9 through 12, were, on average, within 2.0% of those made by image cytometry.

  10. Optics and experimental resolution of the Heidelberg slit-scan flow fluorometer

    NASA Astrophysics Data System (ADS)

    Hausmann, Michael; Wickert, Burkhard; Vogel, Michael; Schurwanz, Michael; Doelle, Juergen; Wolf, Dietmar; Aldinger, Klaus; Cremer, Christoph G.

    1996-01-01

    Slit-scan flow fluorometry is a laser-technological approach for accelerated screening and sorting of fluorescence labelled metaphase chromosomes. Details of the optics of the Heidelberg slit-scan sorter are presented. In a fluid stream the fluorescence labelled chromosomes rapidly pass one at a time by a scanning laser beam. The laser can be focused by a less complex optic consisting of only a few commercially available lenses. The laser intensity distribution around the focus was measured for 488 nm for two lens configurations. Although the light distribution obtained by such an optic is normally not aberration free, the requirements of a 'ribbonlike' shape in the center of the fluid stream can be fulfilled. Since the chromosomes are oriented perpendicularly to the laser beam by hydrodynamic focusing of the fluid stream, the fluorescence intensity along the chromosome axis can be measured time (equals spatially) resolved. According to their intensity profiles the chromosomes can be classified. Signal processing of the profiles can be performed in less than 600 microseconds, so that in the order of hundred chromosomes per second can be sorted out by a computer controlled electro-acoustic sorting unit. The final spatial resolution of a slit-scan flow sorter is not only affected by the focusing optics of the laser but also by the fluid stream, the detection optics and electronics, as well as by the computer analysis algorithm. Calculations often consider only the optics under ideal conditions. Here, a method is shown how to estimate the overall resolution of a slit-scan flow fluorometer experimentally. According to this criterion the resolution of the Heidelberg slit-scan sorter for 488 nm fluorescence excitation was estimated to be 2.4 micrometer in its basic optical configuration and 1.7 micrometer with additional correction of chromatic aberration effects.

  11. Line-scanning fiber bundle endomicroscopy with a virtual detector slit

    PubMed Central

    Hughes, Michael; Yang, Guang-Zhong

    2016-01-01

    Coherent fiber bundles can be used to relay the image plane from the distal tip of an endomicroscope to an external confocal microscopy system. The frame rate is therefore determined by the speed of the microscope’s laser scanning system which, at 10-20 Hz, may be undesirably low for in vivo clinical applications. Line-scanning allows an increase in the frame rate by an order of magnitude in exchange for some loss of optical sectioning, but the width of the detector slit cannot easily be adapted to suit different imaging conditions. The rolling shutter of a CMOS camera can be used as a virtual detector slit for a bench-top line-scanning confocal microscope, and here we extend this idea to endomicroscopy. By synchronizing the camera rolling shutter with a scanning laser line we achieve confocal imaging with an electronically variable detector slit. This architecture allows us to acquire every other frame with the detector slit offset by a known distance, and we show that subtracting this second image leads to improved optical sectioning. PMID:27375942

  12. Slit-scanning microscope with a high-NA objective lens for analysis of synaptic function

    NASA Astrophysics Data System (ADS)

    Sakurai, Takashi; Wakazono, Yoshihiko; Yamamoto, Seiji; Terakawa, Susumu

    2004-07-01

    By employing the total internal reflection fluorescence (TIRF) microscope with an ultra high NA (1.65) objective lens, we demonstrated detailed dynamics of exocytosis in various types of secretory vesicles. However, the TIRF microscopy could be applied to observations only on the plasma membrane and its immediate vicinity. To observe the vesicles in the deeper region of cytoplasm, we modified the TIRF optics to project a slit beam thinner than 1 μm in width to the cell. The slit beam illumination spotted single secretory vesicles inside the cell better and their movement and exocytosis easier. By scanning the slit beam, a fluorescence microscopy was possible at a high signal-to-noise ratio useful for measurement and analysis of single exocytosis in neurons and endocrine cells.

  13. Reduction of scatter in diagnostic radiology by means of a scanning multiple slit assembly.

    PubMed

    Barnes, G T; Cleare, H M; Brezovich, I A

    1976-09-01

    Evidence is presented that an array of long, narrow beam-defining slits scanning a patient coupled with scatter-eliminating slots beneath the patient will substantially reduce scatter in diagnostic radiology. Scatter/primary ratios and the distribution of scatter in the plane of the image detector have been measured as a function of slit width and slot depth for a long, narrow beam-defining geometry. Using these data, calculations for the scatter/primary ratio incident on the image detector are made for a multiple slit assembly and compared with conventional grids. An improvement in contrast is obtained with little or no increase in patient exposure. Design considerations for the construction of such an array and data trends are discussed.

  14. Slit-scanning analysis of dicentric chromosomes: Different approaches for an automated biological dosimetry

    SciTech Connect

    Beisker, W.; Weller, E.M.; Nuesse, M. )

    1993-01-01

    The analysis of dicentric chromosomes is an important method for applications in biological dosimetry. Automation using slit-scanning flow cytometric analysis requires a careful estimation of preparational and instrumental artifacts. As long as reliable techniques for FISH techniques or immunological kinetochore staining in suspension have not been developed, special interest is directed to methods for evaluating artifacts by instrumental or mathematical procedures. The authors present applications for detection of dicentric chromosomes in mammalian cell cultures as well as in human lymphocytes by multiparameter slit-scanning techniques. The improvement of the sensitivity by mathematical analysis of the profiles as well as by simultaneous use of different DNA dyes with multilaser fluorescence excitation is discussed.

  15. The SL SCAN-1: Fourier Domain Optical Coherence Tomography Integrated into a Slit Lamp

    NASA Astrophysics Data System (ADS)

    Verbraak, F. D.; Stehouwer, M.

    The detailed cross-sectional images of OCT can be used for diagnosis and follow-up, assessing therapeutic success or failure. Recently, the OCT technology has been implemented in a small unit compatible with existing slit lamps. This increases the efficiency of the routine clinical examination of a patient, will increase the comfort of the patient, and saves time. Additionally, the posterior segment can be scanned through a handheld lens and even through a three-mirror lens.

  16. Bilateral Circumscribed Posterior Keratoconus: Visualization by Ultrasound Biomicroscopy and Slit-Scanning Topography Analysis

    PubMed Central

    Rejdak, Robert; Nowomiejska, Katarzyna; Haszcz, Dariusz; Jünemann, Anselm G. M.

    2012-01-01

    This paper documents a rare nonprogressive developmental disorder—bilateral circumscribed posterior keratoconus—in a 60-year-old man referred for a cataract surgery. For the first time ultrasound biomicroscopy was used to visualise the local anterior bulging of the posterior corneal surface with concomitant thinning of the stroma. The amount of localized posterior depression, corneal thickness and the refractive power of both the posterior and anterior corneal curvature were measured using slit-scanning topography analysis (Orbscan). PMID:22496963

  17. Comparison of dual rotating Scheimpflug-Placido, swept-source optical coherence tomography, and Placido-scanning-slit systems.

    PubMed

    Lee, Yong Woo; Choi, Chul Young; Yoon, Geun Young

    2015-05-01

    To compare measurements of corneal indices using dual rotating Scheimpflug-Placido, swept-source optical coherence tomography (OCT), and Placido-scanning-slit systems. Kangbuk Samsung Hospital, Seoul, South Korea. Prospective evaluation of diagnostic tests. Corneal topography measurements were performed using dual rotating Scheimpflug-Placido (Galilei G2), swept-source OCT (Casia SS-1000), and Placido-scanning-slit (Orbscan IIz) systems. The intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to evaluate the agreement between measurements. Fifty post-refractive surgery eyes and 50 normal eyes were evaluated. The agreement in anterior keratometry and pachymetry between the 3 devices was high in both groups (ICC > 0.9). In both groups, the ICC values for posterior keratometry and eccentricity were high between the dual rotating Scheimpflug-Placido and swept-source OCT systems (ICC > 0.9) but not between the Placido-scanning-slit system and the other 2 systems. The Placido-scanning-slit system yielded much steeper values for posterior keratometry in both groups (P < .05). The ICC values for posterior corneal elevation were lower than 0.9 between all 3 devices. The dual rotating Scheimpflug-Placido and swept-source OCT systems showed relatively higher ICC values than the Placido-scanning-slit system in both groups. Maximum posterior elevations were highest with the Placido-scanning-slit system followed by the swept-source OCT system and then the dual rotating Scheimpflug-Placido system. Anterior keratometry obtained using 3 devices showed high degrees of agreement. Posterior keratometry and eccentricity showed greater agreement between the dual rotating Scheimpflug-Placido and swept-source OCT systems than with the Placido-scanning-slit system. The dual rotating Scheimpflug-Placido and swept-source OCT systems were equivalent in detecting the shape of the cornea and could be considered interchangeable. Copyright © 2015. Published by Elsevier

  18. Knotting of linear DNA in nano-slits and nano-channels: a numerical study.

    PubMed

    Orlandini, Enzo; Micheletti, Cristian

    2013-03-01

    The amount and type of self-entanglement of DNA filaments is significantly affected by spatial confinement, which is ubiquitous in biological systems. Motivated by recent advancements in single DNA molecule experiments based on nanofluidic devices and by the introduction of algorithms capable of detecting knots in open chains, we investigate numerically the entanglement of linear, open DNA chains confined inside nano-slits. The results regard the abundance, type, and length of occurring knots and are compared with recent findings for DNA inside nano-channels. In both cases, the width of the confining region, D, spans the 30 nm-1 μm range and the confined DNA chains are 1-4 μm long. It is found that the knotting probability is maximum for slit widths in the 70-100 nm range. However, over the considered DNA contour lengths, the maximum incidence of knots remains below 20%, while for channel confinement it tops 50%. Further differences of the entanglement are seen for the average contour length of the knotted region, which drops significantly below D ~100 nm for channel-confinement, while it stays approximately constant for slit-like confinement. These properties ought to reverberate in different kinetic properties of linear DNA depending on confinement and could be detectable experimentally or exploitable in nano-technological applications.

  19. Imaging of aphakic intraocular lens with a slit-scanning tomography system

    NASA Astrophysics Data System (ADS)

    Oliveira, Cristina M.; Almeida, J. B.; Franco, S.

    2011-05-01

    Nowadays, cataract extraction with IOL implantation aims not only to restore the crystalline lens' transparency, but also to improve patients' retinal image quality. The refractive outcome and visual quality in pseudophakic eyes is mainly determined by the combination of corneal and internal optics resulting from the implanted IOLs. The optical function of the IOLs depends on its position in the eye. The IOL distance to the corneal apex determines the optical power needed for optical correction. In this paper it is described the usage of a slit-scanning imaging system to determine IOL positioning. Through the projection of the light from a slit onto the eye, this tomography system allows to acquire multiple sections of the anterior eye segment, at different meridians. The developed system's software corrects geometric and optical distortion of the images and provides 3-dimentional models of the eye's structures from the 2-dimensional sections. With this noninvasive technique, cross-sectional images of an eye with an aphakic IOL were obtained in order to reconstruct its 3- dimensional model of the lens and assess its position in the anterior segment camera.

  20. Breadboard linear array scan imager program

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The performance was evaluated of large scale integration photodiode arrays in a linear array scan imaging system breadboard for application to multispectral remote sensing of the earth's resources. Objectives, approach, implementation, and test results of the program are presented.

  1. Slit-scan flow cytometry for consistent high resolution DNA analysis of X- and Y-chromosome bearing sperm.

    PubMed

    Rens, W; Welch, G R; Houck, D W; van Oven, C H; Johnson, L A

    1996-10-01

    This paper describes the application of slit-scan flow cytometry for accurate DNA analysis of X- and Y-chromosome bearing sperm. The introduction of the slit-scanning technique was initiated to improve the consistency in resolution of the X and Y population from donor to donor. An optimal resolution is essential for high purity sorting of X and Y sperm, as the difference in DNA content is small (3-4%) in most mammals. This difference is the discriminatory parameter for the flow cytometric sorting of the two populations. Our approach was to focus on the role of the sperm tail in the detection process. Slit-scan flow cytometric analysis allows the whole sperm to be spatially analyzed along the direction of flow. Sperm were stained with Dansyl Lysine, a UV excitable fluorescent membrane dye, which stained the head, midpiece, and principal piece. Analysis of these stained sperm showed that there was no difference between the relative number of sperm that travel headfirst or tailfirst through the detection zone of the flow cytometer. The influence of sperm with coiled tails on DNA analysis was also investigated. The proportion of sperm with coiled tails influences semen quality. The standard X-Y separation procedure uses Hoechst 33342, which stains all intact sperm, both living and dead. Propidium iodide was added to discriminate the dead sperm population. Slit-scan analysis showed that measurement of a sample containing a high proportion of living sperm with coiled tails results in an inferior DNA histogram and reduced X-Y resolution. Sperm with coiled tails can result in a lower detected fluorescence intensity, but the reason for this is unclear. Slit-scan flow cytometry allows exclusion of sperm with coiled tails from the analysis, resulting in a restoration of high resolution of X- and Y-chromosome bearing sperm populations.

  2. Estimation of the frequency of malformed sperm by slit scan flow cytometry

    SciTech Connect

    Halamka, J.; Gray, J.W.; Gledhill, B.L.; Lake, S.; Wyrobek, A.J.

    1984-01-01

    An investigation was made of the utility of Slit Scan Flow Cytometry (SSFCM) for measuring the frequencies of malformed sperm heads in control and mutagen treated B6C3F1/CRL mice. In SSFCM, fluorescence profiles of sperm heads stained with the DNA-specific fluorescent dye acriflavine were recorded for sperm flowing lengthwise through a 2.5-..mu..m-thick laser beam. Malformed sperm were detected as having fluorescence profiles that differed substantially from an average fluorescence profile for sperm from untreated mice. Fluorescence profiles were measured for 500 sperm per mouse from five control mice, five mice injected intraperitoneally daily for 5 days with a total of 375 mg/kg of body weight methyl methane sulfonate (MMS), and for 30 mice injected intraperitoneally daily for 5 days with total doses of procarbazine ranging from 125 mg/kg to 1250 mg/kg. Sperm were collected from the caudae epididymides 35 days after the last injection. Frequencies of malformed sperm in these samples were also estimated by visual analysis. All samples were analyzed in double blind fashion. The visual and SSFCM malformed sperm frequencies for the samples from control, MMS-treated, and procarbazine-treated mice were correlated. A dose effect was seen with both the visual and SSFCM estimates for the sperm from the procarbazine-treated mice. 8 references 3 figures.

  3. Quantification of mammalian sperm morphology by slit-scan flow cytometry

    SciTech Connect

    Benaron, D.A.; Gray, J.W.; Gledhill, B.L.; Lake, S.; Wyrobek, A.J.; Young, I.T.

    1982-03-01

    The head shapes of mammalian sperm have been measured by slit-scan flow cytometry (SSFCM). In this approach, the distribution of fluorescence along acriflavine stained mammalian sperm is recorded and used as a measure of head shape. Fluorescence profiles were measured for sperm from mice, rabbits, hamsters, and bulls, and for sperm from mice exposed to testicular x-irradiation from 0 to 900 rads. The profiles for sperm from nonirradiated animals were characteristic of each species and were reproducible from sperm to sperm. Some of the fluorescence profiles for sperm from the irradiated mice differed significantly from the profiles usually measured for sperm from exposed mice. An algorithm was developed to determine the frequency of these sperm. The estimated frequencies of atypical profiles correlated well (r . 0.99) with the frequencies of abnormally shaped sperm determined by microscopic scoring. The maximum SSFCM sensitivity (minimum detectable dose . 199 rad) was not as high as that for the visual assay (minimum detectable dose . 116 rad). However, only 100 profiles were measured by SSFCM at each dose while at least 500 sperm were scored visually at each dose. The sensitivity of the SSFCM assay should be increased substantially by measuring more profiles. The objective nature of SSFCM couple with the high correlation with results from the visually based assay of morphology suggests the use of SSFCM to measure frequencies of misshapen sperm when testing for mutagens or monitoring for effects of environmental contaminants.

  4. Quantification of mammalian sperm morphology by slit-scan flow cytometry

    SciTech Connect

    Benaron, D.A.; Gray, J.W.; Gledhill, B.L.; Lake, S.; Wyrobek, A.J.; Young, I.T.

    1982-01-01

    The head shapes of mammalian sperm were measured by slit-scan flow cytometry (SSFCM). Fluorescence profiles were measured for sperm from mice, rabbits, hamsters, and bulls, and for sperm from mice, rabbits, hamsters, and bulls, and for sperm from mice exposed to testicular x-irradiation from 0 to 900 rads. Some of the fluorescence profiles for sperm from the irradiated mice differed significantly from the profiles usually measured for sperm from unexposed mice. An algorithm was developed to determine the frequency of these sperm. The estimated frequencies of atypical profiles correlated well with the frequencies of abnormally shaped sperm determined by microscopic scoring. The maximum SSFCM sensitivity was not as high as that for the visual assay. However, only 100 profiles were measured by SSFCM at each dose while at least 500 sperm were scored visually at each dose. The sensitivity of the SSFCM assay should be increased substantially by measuring more profiles. The objective nature of SSFCM coupled with the high correlation with results from the visually based assay of morphology suggests the use of SSFCM to measure frequencies of misshapen sperm when testing for mutagens or monitoring for effects of environmental contaminants.

  5. Scanning-slit photon counting x-ray imaging system using a microchannel plate detector.

    PubMed

    Shikhaliev, Polad M; Xu, Tong; Le, Huy; Molloi, Sabee

    2004-05-01

    An experimental prototype of a novel photon counting x-ray imaging system was evaluated. This system is based on an "edge-on" microchannel plate (MCP) detector and utilizes scanning slit imaging configuration. The detector is capable of photon counting, direct conversion, high spatial resolution, controllable physical charge amplification, quantum limited and scatter free operation. The detector provides a 60 mm wide field of view (FOV) and its count rate is 200 kHz for the entire FOV. The count rate of the current system is limited by the position encoding electronics, which has a single input for all events from the entire detector, and incorporates a single channel ADC with 1 micros conversion time. It is shown that the count rate can potentially be improved to clinically acceptable levels using multichannel application specific integrated circuit (ASIC) electronics and multi-slit image acquisition geometry. For a typical acquisition time used in this study, the image noise was measured to be less than the typically acceptable noise level for medical x-ray imaging. It is anticipated that the noise level will be also low after the implementation of the ASIC electronics. The quantum efficiency of the detector was measured to be 40%-56% for an energy range of 50-90 kVp for MCPs used in this study and can be improved to > 80% using MCPs with the optimized parameters. Images of resolution and anthropomorphic phantoms were acquired at an x-ray tube voltage of 50 kVp. The value of contrast transfer function for the detector was measured to be 0.5 at a spatial frequency of 5 lp/mm. The intrinsic spatial resolution of the system is 28 microm FWHM and was limited by the accuracy of the time-to-digital conversion of the position encoding electronics. Given the advantages of the edge-on MCP detector such as direct conversion and physical charge amplification, it can potentially be applied to mammography and chest radiography.

  6. Slit-scanning differential x-ray phase-contrast mammography: proof-of-concept experimental studies.

    PubMed

    Koehler, Thomas; Daerr, Heiner; Martens, Gerhard; Kuhn, Norbert; Löscher, Stefan; van Stevendaal, Udo; Roessl, Ewald

    2015-04-01

    The purpose of this work is to investigate the feasibility of grating-based, differential phase-contrast, full-field digital mammography (FFDM) in terms of the requirements for field-of-view (FOV), mechanical stability, and scan time. A rigid, actuator-free Talbot interferometric unit was designed and integrated into a state-of-the-art x-ray slit-scanning mammography system, namely, the Philips MicroDose L30 FFDM system. A dedicated phase-acquisition and phase retrieval method was developed and implemented that exploits the redundancy of the data acquisition inherent to the slit-scanning approach to image generation of the system. No modifications to the scan arm motion control were implemented. The authors achieve a FOV of 160 × 196 mm consisting of two disjoint areas measuring 77 × 196 mm with a gap of 6 mm between them. Typical scanning times vary between 10 and 15 s and dose levels are lower than typical FFDM doses for conventional scans with identical acquisition parameters due to the presence of the source-grating G0. Only minor to moderate artifacts are observed in the three reconstructed images, indicating that mechanical vibrations induced by other system components do not prevent the use of the platform for phase contrast imaging. To the best of our knowledge, this is the first attempt to integrate x-ray gratings hardware into a clinical mammography unit. The results demonstrate that a scanning differential phase contrast FFDM system that meets the requirements of FOV, stability, scan time, and dose can be build.

  7. A Linear Magnetic Field Scan Driver.

    PubMed

    Quine, Richard W; Czechowski, Tomasz; Eaton, Gareth R

    2009-02-01

    A linear magnetic field scan driver was developed to provide a rapidly scanning magnetic field for use in electron paramagnetic resonance (EPR) spectroscopy. The driver consists of two parts: a digitally synthesized ramp waveform generator and a power amplifier to drive the magnetic field coils. Additionally, the driver provides a trigger signal to a data collection digitizer that is synchronized to the ramp waveform. The driver can also drive an arbitrary current waveform supplied from an external source. The waveform generator is computer controlled through a serial data interface. Additional functions are controlled by the user from the driver front panel. The frequency and amplitude of the waveform are each separately controlled with 12-bit resolution (one part in 4,096). Several versions of the driver have been built with different frequency and amplitude ranges. Frequencies range from 500 to 20,000 Hz. Field sweep amplitudes range up to 80 G(pp). This article also gives a brief description of the field coils that are driven by the driver.

  8. A Linear Magnetic Field Scan Driver

    PubMed Central

    QUINE, RICHARD W.; CZECHOWSKI, TOMASZ; EATON, GARETH R.

    2009-01-01

    A linear magnetic field scan driver was developed to provide a rapidly scanning magnetic field for use in electron paramagnetic resonance (EPR) spectroscopy. The driver consists of two parts: a digitally synthesized ramp waveform generator and a power amplifier to drive the magnetic field coils. Additionally, the driver provides a trigger signal to a data collection digitizer that is synchronized to the ramp waveform. The driver can also drive an arbitrary current waveform supplied from an external source. The waveform generator is computer controlled through a serial data interface. Additional functions are controlled by the user from the driver front panel. The frequency and amplitude of the waveform are each separately controlled with 12-bit resolution (one part in 4,096). Several versions of the driver have been built with different frequency and amplitude ranges. Frequencies range from 500 to 20,000 Hz. Field sweep amplitudes range up to 80 Gpp. This article also gives a brief description of the field coils that are driven by the driver. PMID:19838315

  9. Modular multimodal swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography scan-head for surgical microscope-integrated and slit-lamp imaging

    NASA Astrophysics Data System (ADS)

    Malone, Joseph D.; Li, Jianwei D.; El-Haddad, Mohamed T.; Joos, Karen M.; Patel, Shriji N.; Tao, Yuankai K.

    2017-02-01

    Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) enable noninvasive in vivo diagnostic imaging and provide complementary en face and depth-resolved visualization of ophthalmic structures, respectively. We previously demonstrated concurrent multimodal swept-source spectrally encoded scanning laser ophthalmoscopy and OCT (SS-SESLO-OCT) at 1060 nm using a swept-source and double clad fiber coupler. Here, we present system enhancements and novel designs for a modular SS-SESLO-OCT scan-head that can be coupled to ophthalmic surgical microscope-integrated and slit-lamp imaging optics. Multimodal SS-SESLO-OCT was demonstrated using a custom-built swept-source OCT engine with a 200 kHz 1060 nm source that was optically buffered for concurrent SESLO and OCT imaging at 100% duty cycle and 400 kHz sweep-rate. A shared optical relay and fast-axis galvanometer ensured inherent co-registration between SESLO and OCT field-of-views and concurrent acquisition of an en face SESLO image with each OCT cross-section. SESLO and OCT frames were acquired at 200 fps with 2560 x 2000 pix. (spectral x lateral). We show in vivo human ophthalmic imaging data using surgical microscope-integrated and slit-lamp imaging relays to demonstrate the utility of our SS-SESLO-OCT design. Our self-contained modular scan-head can be used for either intraoperative guidance or clinical diagnostics and reduces the complexity, cost, and maintenance required for clinical translation of these technologies. We believe concurrent multimodal SS-SESLO-OCT may benefit 1) intraoperative imaging by allowing for real-time surgical feedback, instrument tracking, and overlays of computationally extracted image-based surrogate biomarkers of disease, and 2) slit-lamp imaging by enabling aiming, image registration, and multi-field mosaicking.

  10. Corneal thickness and elevation measurements using swept-source optical coherence tomography and slit scanning topography in normal and keratoconic eyes.

    PubMed

    Jhanji, Vishal; Yang, Bingzhi; Yu, Marco; Ye, Cong; Leung, Christopher K S

    2013-11-01

    To compare corneal thickness and corneal elevation using swept source optical coherence tomography and slit scanning topography. Prospective study. 41 normal and 46 keratoconus subjects. All eyes were imaged using swept source optical coherence tomography and slit scanning tomography during the same visit. Mean corneal thickness and best-fit sphere measurements were compared between the instruments. Agreement of measurements between swept source optical coherence tomography and scanning slit topography was analyzed. Intra-rater reproducibility coefficient and intraclass correlation coefficient were evaluated. In normal eyes, central corneal thickness measured by swept source optical coherence tomography was thinner compared with slit scanning topography (p < 0.0001) and ultrasound pachymetry (p = < .0001). Ultrasound pachymetry readings had better 95% limits of agreement with swept source optical coherence tomography than slit scanning topography. In keratoconus eyes, central corneal thickness was thinner on swept source optical coherence tomography than slit scanning topography (p = 0.081) and ultrasound pachymetry (p = 0.001). There were significant differences between thinnest corneal thickness, and, anterior and posterior best-fit sphere measurements between both instruments (p < 0.05 for all). Overall, reproducibility coefficients and intraclass correlation coefficients were significantly better with swept source optical coherence tomography for measurement of central corneal thickness, anterior best-fit sphere and, posterior best-fit sphere (all p < 0.001). Corneal thickness and elevation measurements were significantly different between swept source optical coherence tomography and slit scanning topography. With better reproducibility coefficients and intraclass correlation coefficients, swept source optical coherence tomography may provide a reliable alternative for measurement of corneal parameters. © 2013 The Authors. Clinical

  11. Tissue imaging of myocardial infarct regions by a slit-scanning Raman microscope

    NASA Astrophysics Data System (ADS)

    Ogawa, Mitsugu; Harada, Yoshinori; Yamaoka, Yoshihisa; Fujita, Katsumasa; Takamatsu, Tetsuro

    2009-02-01

    Estimating the distribution of myocardial fibrosis after myocardial infarct is important for appropriate therapeutic planning. Here, we applied a Raman confocal microscope equipped with slit scanner for molecular tissue imaging of rat infarcted hearts. Raman spectra of the cytoplasm of cardiomyocytes included the resonance Raman bands at 751, 1130 and 1582 cm-1 arising mainly from reduced b- and c- type cytochromes. Raman spectra of fibrotic tissues at the borderzone of old myocardial infarct were highly consistent with that of collagen type I. Based on these findings, we successfully obtained Raman tissue images of a cardiomyocyte and surrounding collagen at the cellular level.

  12. Development of a two-parameter slit-scan flow cytometer for screening of normal and aberrant chromosomes: application to a karyotype of Sus scrofa domestica (pig)

    NASA Astrophysics Data System (ADS)

    Hausmann, Michael; Doelle, Juergen; Arnold, Armin; Stepanow, Boris; Wickert, Burkhard; Boscher, Jeannine; Popescu, Paul C.; Cremer, Christoph

    1992-07-01

    Laser fluorescence activated slit-scan flow cytometry offers an approach to a fast, quantitative characterization of chromosomes due to morphological features. It can be applied for screening of chromosomal abnormalities. We give a preliminary report on the development of the Heidelberg slit-scan flow cytometer. Time-resolved measurement of the fluorescence intensity along the chromosome axis can be registered simultaneously for two parameters when the chromosome axis can be registered simultaneously for two parameters when the chromosome passes perpendicularly through a narrowly focused laser beam combined by a detection slit in the image plane. So far automated data analysis has been performed off-line on a PC. In its final performance, the Heidelberg slit-scan flow cytometer will achieve on-line data analysis that allows an electro-acoustical sorting of chromosomes of interest. Interest is high in the agriculture field to study chromosome aberrations that influence the size of litters in pig (Sus scrofa domestica) breeding. Slit-scan measurements have been performed to characterize chromosomes of pigs; we present results for chromosome 1 and a translocation chromosome 6/15.

  13. Linear mass scans in quadrupole ion traps using the inverse Mathieu q scan.

    PubMed

    Snyder, Dalton T; Pulliam, Christopher J; Cooks, R Graham

    2016-11-30

    Secular frequency scanning is a method of mass selectively scanning ions out of a quadrupole ion trap by linearly ramping the frequency of the resonance ejection signal through ion secular frequencies at constant rf amplitude and frequency. The method is electronically much simpler than resonance ejection but it requires a complex nonlinear calibration procedure to correlate mass-to-charge with time. A method of secular frequency scanning in quadrupole ion traps is described in which mass-to-charge is linear with time. This method, termed an "inverse Mathieu q scan", contrasts with linear frequency sweeping which requires a complex nonlinear mass calibration procedure. In the current method, mass scans are forced to be linear with time by scanning the frequency of the supplementary ac so that there is an inverse relationship between the ejected ion's Mathieu q parameter and time. In all cases, excellent mass spectral linearity is observed. The rf amplitude is shown to control both the scan range and the scan rate, whereas the ac amplitude and scan rate influence the mass resolution. The scan rate depends linearly on the rf amplitude, a unique feature of this scan. Although changes in either rf or ac amplitude affect the positions of peaks in time, they do not change the mass calibration procedure since this only requires a simple linear fit of m/z vs time. Space charge effects are shown to give rise to significant changes in resolution as well as to mass shifts. A method of secular frequency scanning which provides a linear mass scale has been demonstrated. The inverse Mathieu q scan offers a significant increase in mass range and power savings while maintaining access to linearity, paving the way for a mass spectrometer based completely on ac waveforms for ion isolation, ion activation, and ion ejection. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Effect of post crosslinking haze on the repeatability of Scheimpflug-based and slit-scanning imaging devices

    PubMed Central

    Shetty, Rohit; Agrawal, Aarti; Deshmukh, Rashmi; Kaweri, Luci; Rao, Harsha L; Nagaraja, Harsha; Jayadev, Chaitra

    2017-01-01

    Purpose: The aim of this study was to analyze the effect of postcollagen crosslinking (CXL) haze on the measurement and repeatability of pachymetry and mean keratometry (Km) of four corneal topographers. Materials and Methods: Sixty eyes of sixty patients with progressive keratoconus who had undergone accelerated CXL (ACXL) underwent imaging with a scanning slit imaging device (Orbscan II) and three Scheimpflug imaging devices (Pentacam HR, Sirius, and Galilei). Post-ACXL haze was measured using the densitometry software on the Pentacam HR. Readings of the thinnest corneal thickness (TCT) and Km from three scans of each device were analyzed. Effect of haze on the repeatability of TCT and Km measurements was evaluated using regression models. Repeatability was assessed by coefficient of variation. Results: Corneal densitometry in different zones affected the repeatability of TCT measurement of Orbscan (P < 0.05) significantly but not the repeatability of TCT with Pentacam HR and Sirius (P = 0.03 and 0.05, respectively). Km values were affected by haze when measured with the Pentacam HR (P < 0.05). The repeatability of Km readings for all devices was unaffected by haze. In the anterior 0–2 mm and 2–6 mm zone, TCT (P = 0.43 and 0.45, respectively), Km values (P = 0.4 and 0.6, respectively), repeatability of TCT (P = 0.1 in both zones), and Km (P = 0.5 and 0.1, respectively) with Galilei were found to be the most reliable. Conclusion: Galilei measurements appear to be least affected by post-ACXL haze when compared with other devices. Hence, topography measurements in the presence of haze need to be interpreted with caution. PMID:28513495

  15. Clinical applications of a real-time scanning-slit confocal microscope designed for real-time observations of the in-vivo human cornea

    NASA Astrophysics Data System (ADS)

    Masters, Barry R.

    1995-05-01

    We describe a new, real-time, flying slit confocal microscope, that has unique features and imaging characteristics for in vivo human ocular imaging. In vivo real-time confocal microscopy is currently used to investigate the tear film, renewal of the ocular surface, the role of epithelial innervation in epithelial cell proliferation, wound healing, kinetics of drug penetration, the effects of laser refractive surgery on the keratocyte activation and distribution in the stroma, and the nature of endothelial defects. The following clinical examples will be presented and discussed: confocal microscopy of normal human basal and wing cells in the epithelium, confocal microscopy of lamellar and penetrating corneal grafts, confocal microscopy of corneal ulcer, confocal microscopy of scar formation after herpes keratitis, and confocal microscopy of corneal innervation. The use of scanning slit confocal microscopes has unique advantages over other instrumental systems based on pinhole-containing Nipkow disks (tandem-scanning confocal microscopes) for clinical in vivo confocal microscopy.

  16. Automatic scan registration using 3D linear and planar features

    NASA Astrophysics Data System (ADS)

    Yao, Jian; Ruggeri, Mauro R.; Taddei, Pierluigi; Sequeira, Vítor

    2010-09-01

    We present a common framework for accurate and automatic registration of two geometrically complex 3D range scans by using linear or planar features. The linear features of a range scan are extracted with an efficient split-and-merge line-fitting algorithm, which refines 2D edges extracted from the associated reflectance image considering the corresponding 3D depth information. The planar features are extracted employing a robust planar segmentation method, which partitions a range image into a set of planar patches. We propose an efficient probability-based RANSAC algorithm to automatically register two overlapping range scans. Our algorithm searches for matching pairs of linear (planar) features in the two range scans leading to good alignments. Line orientation (plane normal) angles and line (plane) distances formed by pairs of linear (planar) features are invariant with respect to the rigid transformation and are utilized to find candidate matches. To efficiently seek for candidate pairs and groups of matched features we build a fast search codebook. Given two sets of matched features, the rigid transformation between two scans is computed by using iterative linear optimization algorithms. The efficiency and accuracy of our registration algorithm were evaluated on several challenging range data sets.

  17. A light sheet confocal microscope for image cytometry with a variable linear slit detector

    NASA Astrophysics Data System (ADS)

    Hutcheson, Joshua A.; Khan, Foysal Z.; Powless, Amy J.; Benson, Devin; Hunter, Courtney; Fritsch, Ingrid; Muldoon, Timothy J.

    2016-03-01

    We present a light sheet confocal microscope (LSCM) capable of high-resolution imaging of cell suspensions in a microfluidic environment. In lieu of conventional pressure-driven flow or mechanical translation of the samples, we have employed a novel method of fluid transport, redox-magnetohydrodynamics (redox-MHD). This method achieves fluid motion by inducing a small current into the suspension in the presence of a magnetic field via electrodes patterned onto a silicon chip. This on-chip transportation requires no moving parts, and is coupled to the remainder of the imaging system. The microscopy system comprises a 450 nm diode 20 mW laser coupled to a single mode fiber and a cylindrical lens that converges the light sheet into the back aperture of a 10x, 0.3 NA objective lens in an epi-illumination configuration. The emission pathway contains a 150 mm tube lens that focuses the light onto the linear sensor at the conjugate image plane. The linear sensor (ELiiXA+ 8k/4k) has three lateral binning modes which enables variable detection aperture widths between 5, 10, or 20 μm, which can be used to vary axial resolution. We have demonstrated redox-MHD-enabled light sheet microscopy in suspension of fluorescent polystyrene beads. This approach has potential as a high-throughput image cytometer with myriad cellular diagnostic applications.

  18. LINEAR SCANNING METHOD BASED ON THE SAFT COARRAY

    SciTech Connect

    Martin, C. J.; Martinez-Graullera, O.; Romero, D.; Ullate, L. G.; Higuti, R. T.

    2010-02-22

    This work presents a method to obtain B-scan images based on linear array scanning and 2R-SAFT. Using this technique some advantages are obtained: the ultrasonic system is very simple; it avoids the grating lobes formation, characteristic in conventional SAFT; and subaperture size and focussing lens (to compensate emission-reception) can be adapted dynamically to every image point. The proposed method has been experimentally tested in the inspection of CFRP samples.

  19. A fast linear reconstruction method for scanning impedance imaging.

    PubMed

    Liu, Hongze; Hawkins, Aaron R; Schultz, Stephen M; Oliphant, Travis E

    2006-01-01

    Scanning electrical impedance imaging (SII) has been developed and implemented as a novel high resolution imaging modality with the potential of imaging the electrical properties of biological tissues. In this paper, a fast linear model is derived and applied to the impedance image reconstruction of scanning impedance imaging. With the help of both the deblurring concept and the reciprocity principle, this new approach leads to a calibrated approximation of the exact impedance distribution rather than a relative one from the original simplified linear method. Additionally, the method shows much less computational cost than the more straightforward nonlinear inverse method based on the forward model. The kernel function of this new approach is described and compared to the kernel of the simplified linear method. Two-dimensional impedance images of a flower petal and cancer cells are reconstructed using this method. The images reveal details not present in the measured images.

  20. Using Stage- and Slit-Scanning to Improve Contrast and Optical Sectioning in Dual-View Inverted Light Sheet Microscopy (diSPIM).

    PubMed

    Kumar, Abhishek; Christensen, Ryan; Guo, Min; Chandris, Panos; Duncan, William; Wu, Yicong; Santella, Anthony; Moyle, Mark; Winter, Peter W; Colón-Ramos, Daniel; Bao, Zhirong; Shroff, Hari

    2016-08-01

    Dual-view inverted selective plane illumination microscopy (diSPIM) enables high-speed, long-term, four-dimensional (4D) imaging with isotropic spatial resolution. It is also compatible with conventional sample mounting on glass coverslips. However, broadening of the light sheet at distances far from the beam waist and sample-induced scattering degrades diSPIM contrast and optical sectioning. We describe two simple improvements that address both issues and entail no additional hardware modifications to the base diSPIM. First, we demonstrate improved diSPIM sectioning by keeping the light sheet and detection optics stationary, and scanning the sample through the stationary light sheet (rather than scanning the broadening light sheet and detection plane through the stationary sample, as in conventional diSPIM). This stage-scanning approach allows a thinner sheet to be used when imaging laterally extended samples, such as fixed microtubules or motile mitochondria in cell monolayers, and produces finer contrast than does conventional diSPIM. We also used stage-scanning diSPIM to obtain high-quality, 4D nuclear datasets derived from an uncompressed nematode embryo, and performed lineaging analysis to track 97% of cells until twitching. Second, we describe the improvement of contrast in thick, scattering specimens by synchronizing light-sheet synthesis with the rolling, electronic shutter of our scientific complementary metal-oxide-semiconductor (sCMOS) detector. This maneuver forms a virtual confocal slit in the detection path, partially removing out-of-focus light. We demonstrate the applicability of our combined stage- and slit-scanning- methods by imaging pollen grains and nuclear and neuronal structures in live nematode embryos. All acquisition and analysis code is freely available online. © 2016 Marine Biological Laboratory.

  1. Linearization of scan velocity of resonant vibrating-mirror beam deflectors

    DOEpatents

    Yeung, E.S.; Chen, S.L.

    1991-01-15

    A means and method for producing linearization of scan velocity of resonant vibrating-mirror beam deflectors in laser scanning system including presenting an elliptical convex surface to the scanning beam to reflect the scanning beam to the focal plane of the scanning line. The elliptical surface is shaped to produce linear velocity of the reflective scanning beam at the focal plane. Maximization of linearization is accomplished by considering sets of criteria for different scanning applications. 6 figures.

  2. Computational alanine scanning with linear scaling semiempirical quantum mechanical methods.

    PubMed

    Diller, David J; Humblet, Christine; Zhang, Xiaohua; Westerhoff, Lance M

    2010-08-01

    Alanine scanning is a powerful experimental tool for understanding the key interactions in protein-protein interfaces. Linear scaling semiempirical quantum mechanical calculations are now sufficiently fast and robust to allow meaningful calculations on large systems such as proteins, RNA and DNA. In particular, they have proven useful in understanding protein-ligand interactions. Here we ask the question: can these linear scaling quantum mechanical methods developed for protein-ligand scoring be useful for computational alanine scanning? To answer this question, we assembled 15 protein-protein complexes with available crystal structures and sufficient alanine scanning data. In all, the data set contains Delta Delta Gs for 400 single point alanine mutations of these 15 complexes. We show that with only one adjusted parameter the quantum mechanics-based methods outperform both buried accessible surface area and a potential of mean force and compare favorably to a variety of published empirical methods. Finally, we closely examined the outliers in the data set and discuss some of the challenges that arise from this examination.

  3. Non-linear image scanning microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Gregor, Ingo; Ros, Robert; Enderlein, Jörg

    2017-02-01

    Nowadays, multiphoton microscopy can be considered as a routine method for the observation of living cells, organs, up to whole organisms. Second-harmonics generation (SHG) imaging has evolved to a powerful qualitative and label-free method for studying fibrillar structures, like collagen networks. However, examples of super-resolution non-linear microscopy are rare. So far, such approaches require complex setups and advanced synchronization of scanning elements limiting the image acquisition rates. We describe theory and realization of a super-resolution image scanning microscope [1, 2] using two-photon excited fluorescence as well as second-harmonic generation. It requires only minor modifications compared to a classical two-photon laser-scanning microscope and allows image acquisition at the high frame rates of a resonant galvo-scanner. We achieve excellent sensitivity and high frame-rate in combination with two-times improved lateral resolution. We applied this method to fixed cells, collagen hydrogels, as well as living fly embryos. Further, we proofed the excellent image quality of our setup for deep tissue imaging. 1. Müller C.B. and Enderlein J. (2010) Image scanning microscopy. Phys. Rev. Lett. 104(19), 198101. 2. Sheppard C.J.R. (1988) Super-resolution in confocal imaging. Optik (Stuttg) 80 53-54.

  4. Measurements of dimensional accuracy using linear and scanning profile techniques.

    PubMed

    Harrison, A; Huggett, R; Zissis, A

    1992-01-01

    Various measurement methods have been described for the determination of dimensional accuracy and stability of denture base materials. This investigation introduces a computerised coordinate measuring machine (CCMM) and compares it with two methods routinely used for assessment of the accuracy of fit of denture base materials. The results demonstrate that the three methods (digital calipers, optical comparator, and CCMM) are acceptable for linear measurement. The CCMM was also used in its scanning mode to define and to quantify the contour changes of the resin bases. The advantages of the CCMM become apparent when two-dimensional changes require assessment.

  5. An ultraviolet/infrared matrix-assisted laser desorption ionization sample stage integrating scanning knife-edge and slit devices for laser beam analysis.

    PubMed

    Soltwisch, Jens; Dreisewerd, Klaus

    2011-05-15

    A sample stage is described that allows the on-line analysis of laser intensity profiles and spot sizes directly in the ion source of a matrix-assisted laser desorption ionization (MALDI) mass spectrometer. The detector uses either a scanning knife-edge or a narrow slit in combination with diffusing disks for scattering of photons and a pyroelectric sensor for recording the light pulses. The setup was integrated into the sample holder of a oMALDI2(TM) ion source (AB Sciex) and allows parallel analysis of UV- and IR-laser beams at typical UV-/IR-MALDI laser fluences. The concept could be especially useful for a precise control of the laser spot size in MALDI imaging applications. Copyright © 2011 John Wiley & Sons, Ltd.

  6. 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.

  7. Linearization of scan velocity of resonant vibrating-mirror beam deflectors

    DOEpatents

    Yeung, Edward S.; Chen, Shun-Le

    1991-01-15

    A means and method for producing linerization of scan velocity of resonant vibrating-mirror beam deflectors in laser scanning system including presenting an elliptical convex surface to the scanning beam to reflect the scanning beam to the focal plane of the scanning line. The elliptical surface is shaped to produce linear velocity of the reflective scanning beam at the focal plane. Maximization of linerization is accomplished by considering sets of criteria for different scanning applications.

  8. Non-linear optical measurements using a scanned, Bessel beam

    NASA Astrophysics Data System (ADS)

    Collier, Bradley B.; Awasthi, Samir; Lieu, Deborah K.; Chan, James W.

    2015-03-01

    Oftentimes cells are removed from the body for disease diagnosis or cellular research. This typically requires fluorescent labeling followed by sorting with a flow cytometer; however, possible disruption of cellular function or even cell death due to the presence of the label can occur. This may be acceptable for ex vivo applications, but as cells are more frequently moving from the lab to the body, label-free methods of cell sorting are needed to eliminate these issues. This is especially true of the growing field of stem cell research where specialized cells are needed for treatments. Because differentiation processes are not completely efficient, cells must be sorted to eliminate any unwanted cells (i.e. un-differentiated or differentiated into an unwanted cell type). In order to perform label-free measurements, non-linear optics (NLO) have been increasingly utilized for single cell analysis because of their ability to not disrupt cellular function. An optical system was developed for the measurement of NLO in a microfluidic channel similar to a flow cytometer. In order to improve the excitation efficiency of NLO, a scanned Bessel beam was utilized to create a light-sheet across the channel. The system was tested by monitoring twophoton fluorescence from polystyrene microbeads of different sizes. Fluorescence intensity obtained from light-sheet measurements were significantly greater than measurements made using a static Gaussian beam. In addition, the increase in intensity from larger sized beads was more evident for the light-sheet system.

  9. Huffman and linear scanning methods with statistical language models.

    PubMed

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

    2015-03-01

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

  10. Scanning Linear Estimation: Improvements over Region of Interest (ROI) Methods

    PubMed Central

    Kupinski, Meredith K.; Clarkson, Eric W.; Barrett, Harrison H.

    2013-01-01

    In tomographic medical imaging, signal activity is typically estimated by summing voxels from a reconstructed image. We introduce an alternative estimation scheme that operates on the raw projection data and offers a substantial improvement, as measured by the ensemble mean-square error (EMSE), when compared to using voxel values from a maximum-likelihood expectation-maximization (MLEM) reconstruction. The scanning-linear (SL) estimator operates on the raw projection data and is derived as a special case of maximum-likelihood (ML) estimation with a series of approximations to make the calculation tractable. The approximated likelihood accounts for background randomness, measurement noise, and variability in the parameters to be estimated. When signal size and location are known, the SL estimate of signal activity is an unbiased estimator, i.e., the average estimate equals the true value. By contrast, standard algorithms that operate on reconstructed data are subject to unpredictable bias arising from the null functions of the imaging system. The SL method is demonstrated for two different tasks: 1) simultaneously estimating a signal's size, location, and activity; 2) for a fixed signal size and location, estimating activity. Noisy projection data are realistically simulated using measured calibration data from the multi-module multi-resolution (M3R) small-animal SPECT imaging system. For both tasks the same set of images is reconstructed using the MLEM algorithm (80 iterations), and the average and the maximum value within the ROI are calculated for comparison. This comparison shows dramatic improvements in EMSE for the SL estimates. To show that the bias in ROI estimates affects not only absolute values but also relative differences, such as those used to monitor response to therapy, the activity estimation task is repeated for three different signal sizes. PMID:23384998

  11. Scanning linear estimation: improvements over region of interest (ROI) methods.

    PubMed

    Kupinski, Meredith K; Clarkson, Eric W; Barrett, Harrison H

    2013-03-07

    In tomographic medical imaging, a signal activity is typically estimated by summing voxels from a reconstructed image. We introduce an alternative estimation scheme that operates on the raw projection data and offers a substantial improvement, as measured by the ensemble mean-square error (EMSE), when compared to using voxel values from a maximum-likelihood expectation-maximization (MLEM) reconstruction. The scanning-linear (SL) estimator operates on the raw projection data and is derived as a special case of maximum-likelihood estimation with a series of approximations to make the calculation tractable. The approximated likelihood accounts for background randomness, measurement noise and variability in the parameters to be estimated. When signal size and location are known, the SL estimate of signal activity is unbiased, i.e. the average estimate equals the true value. By contrast, unpredictable bias arising from the null functions of the imaging system affect standard algorithms that operate on reconstructed data. The SL method is demonstrated for two different tasks: (1) simultaneously estimating a signal's size, location and activity; (2) for a fixed signal size and location, estimating activity. Noisy projection data are realistically simulated using measured calibration data from the multi-module multi-resolution small-animal SPECT imaging system. For both tasks, the same set of images is reconstructed using the MLEM algorithm (80 iterations), and the average and maximum values within the region of interest (ROI) are calculated for comparison. This comparison shows dramatic improvements in EMSE for the SL estimates. To show that the bias in ROI estimates affects not only absolute values but also relative differences, such as those used to monitor the response to therapy, the activity estimation task is repeated for three different signal sizes.

  12. Day to Day Clinically Relevant Corneal Elevation, Thickness, and Curvature Parameters Using the Orbscan II Scanning Slit Topographer and the Pentacam Scheimpflug Imaging Device

    PubMed Central

    Hashemi, Hassan; Mehravaran, Shiva

    2010-01-01

    The introduction of different techniques and computerized devices into clinical ophthalmology has significantly improved our knowledge of the eyes, optics, and eye conditions. Today, corneal topography is performed with a wide range of devices that implement a variety of techniques. Advance computerized analysis systems provide us with simple and quick evaluation procedures, yet the sophisticated data and clinical information that is generated can only be interpreted with adequate knowledge of the system itself as well as the accepted normal ranges of various properties assessed with these systems. Two computerized topography systems that are in common use are the Orbscan (Bausch and Lomb Inc., Rochester, NY, USA) and the Pentacam (Oculus GmBH, Wetzlar, Germany). The Orbscan is a slit-scanning device and the Pentacam is Scheimpflug imaging device. In this review, we present a brief description of both technologies, the techniques implemented in each device and the acquisition process with each. This will be followed by a list of corneal parameters that need to be assessed in screening patients for refractive surgery. We will discuss how these parameters are displayed, how each parameter may serve as clinic criteria, and how data should be interpreted. We will also try to provide evidence regarding the accuracy of different measurements, and the comparability of the two devices. PMID:20543936

  13. Linear scanning array with bulk ferroelectric-integrated feed network.

    PubMed

    Teo, Peng-Thian; Jose, Kollakompil A; Wang, Ya-Jun; Lee, Ching-Kwang; Varadan, Vijay K

    2002-05-01

    Variable ferroelectric delay line technology has been utilized to implement a proof-of-concept, continuous scanning, ferroelectric integrated phased array antenna system. S21 phase shifts of up to 157 degrees have been achieved from the phase shifter itself via analogous variation of a DC bias. When integrated into a phased array, beam scanning of at least +/-12 degrees is achieved prior to any optimization. Some of the key material requirements, fabrication procedures, characterization, and assembly of the ferroelectric material will be revealed. The design, integration, and performance of the array system using such phased shifters will be presented.

  14. Near-field light focusing by a slit array in a planar metal film with nonuniform slit dielectric material

    NASA Astrophysics Data System (ADS)

    David Wellems, L.; Huang, Danhong

    2012-02-01

    We study the interference of evanescent electromagnetic waves generated from multi-slits in a metal film and demonstrate the anomalous bending of light at infrared frequencies due to negative refraction. We also calculate the diffraction of an incident plane electromagnetic waves by a metallic film with an arbitrary linear array of slits, slit separation, and slit dielectric material. In contrast to a double-convex shaped quartz lens, we show that a planar metallic film with a one-dimensional slit array can also focus polarized light in the near-field region when either the slit width or the slit dielectric material becomes spatially nonuniform.

  15. Image distortion and its correction in linear galvanometric mirrors-based laser-scanning microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Wenbo; Wu, Zhenguo; Zeng, Haishan

    2015-05-01

    To simplify imaging focusing and calibration tasks, a laser-scanning microscope needs to scan at a moderate frame rate. The inertia of a galvanometric scanner leads to time delays when following external commands, which subsequently introduces image distortions that deteriorate as scan frequency increases. Sinusoidal and triangular waveforms were examined as fast axis driving patterns. The interplay among driving pattern, frequency, sampling rate, phase shift, linear scanning range, and their effect on reconstructed images was discussed. Utilizing position feedback from the linear galvo scanners, the effect of response time could be automatically compensated in real time. Precompensated triangular driving waveform offered the least amount of image distortion.

  16. Quantification of breast density with spectral mammography based on a scanned multi-slit photon-counting detector: A feasibility study

    PubMed Central

    Ding, Huanjun; Molloi, Sabee

    2012-01-01

    Purpose A simple and accurate measurement of breast density is crucial for the understanding of its impact in breast cancer risk models. The feasibility to quantify volumetric breast density with a photon-counting spectral mammography system has been investigated using both computer simulations and physical phantom studies. Methods A computer simulation model involved polyenergetic spectra from a tungsten anode x-ray tube and a Si-based photon-counting detector has been evaluated for breast density quantification. The figure-of-merit (FOM), which was defined as the signal-to-noise ratio (SNR) of the dual energy image with respect to the square root of mean glandular dose (MGD), was chosen to optimize the imaging protocols, in terms of tube voltage and splitting energy. A scanning multi-slit photon-counting spectral mammography system has been employed in the experimental study to quantitatively measure breast density using dual energy decomposition with glandular and adipose equivalent phantoms of uniform thickness. Four different phantom studies were designed to evaluate the accuracy of the technique, each of which addressed one specific variable in the phantom configurations, including thickness, density, area and shape. In addition to the standard calibration fitting function used for dual energy decomposition, a modified fitting function has been proposed, which brought the tube voltages used in the imaging tasks as the third variable in dual energy decomposition. Results For an average sized breast of 4.5 cm thick, the FOM was maximized with a tube voltage of 46kVp and a splitting energy of 24 keV. To be consistent with the tube voltage used in current clinical screening exam (~ 32 kVp), the optimal splitting energy was proposed to be 22 keV, which offered a FOM greater than 90% of the optimal value. In the experimental investigation, the root-mean-square (RMS) error in breast density quantification for all four phantom studies was estimated to be

  17. Femoral neck anteversion measurement using linear slot scanning radiography.

    PubMed

    Chimhundu, Chipo; Sivarasu, Sudesh; Steiner, Stefan; Smit, Julian; Douglas, Tania S

    2016-02-01

    Measurements between anatomical landmarks on radiographs are useful for diagnosis and treatment planning in the orthopedic field. Direct measurement on single radiographic images, however, does not truly reflect spatial relationships, as depth information is lost. We used stereo images from a slot scanning X-ray machine to estimate coordinates of three-dimensional (3D) bony landmarks for femoral neck anteversion (FNA) measurement. A set of 7 landmarks consisting of the centre of the femoral head; the centre of the base of the femoral neck; the medial and lateral condyles; the medial and lateral posterior condyles; and finally the centre of the knee; were found to be identifiable and suitable for radiographic measurement. The reconstructed 3D coordinates were then used to define the 3D geometry of the anatomical axes required to estimate FNA. Stereophotogrammetric measurements on a sample of 30 dry right adult femurs were compared to reference values obtained using the Kingsley Olmstead method applied to photographic images. A strong positive correlation (0.998) was found and the mean ± standard deviation of the stereophotogrammetric approach (13.08 ± 6.87)° was comparable to that of the Kingsley Olmstead method (13.14 ± 6.88)°. Intra- and inter-observer reliability were high, with the lower bound of the 95% confidence interval above 0.98 for the intra-class correlation coefficient. The results merit further validation against three dimensional imaging technology such as computed tomography, to confirm stereophotogrammetry as a suitable alternative for FNA measurement.

  18. Highly efficient nanofocusing based on a T-shape micro-slit surrounded with multi-slits.

    PubMed

    Chen, Jianjun; Wang, Chen; Lu, Guowei; Li, Wenqiang; Xiao, Jinghua; Gong, Qihuang

    2012-07-30

    Highly efficient plasmonic nanofocusing is proposed and demonstrated in a T-shape micro-slit surrounded by multi-slits. The nanofocusing phenomenon is achieved based on the multimode interference in the micro-slit, the constructive interference in the T-shape slit, and also the multiple-beam interference of the light radiated from the multi-slits and the transmitted light from the T-shape micro-slit. Because of the large illumination areas of the incident light on the wide slit aperture in the proposed structure, a large amount of light can pass through the wide slit. This leads to a highly efficient nanofocusing. Meanwhile, the wide slit means easy fabrication. In the experiment, the focusing phenomenon in the proposed structure was successfully demonstrated with a scanning near-field optical microscopy (SNOM) technology.

  19. Slit-Robo signaling.

    PubMed

    Blockus, Heike; Chédotal, Alain

    2016-09-01

    Slits are secreted proteins that bind to Roundabout (Robo) receptors. Slit-Robo signaling is best known for mediating axon repulsion in the developing nervous system. However, in recent years the functional repertoire of Slits and Robo has expanded tremendously and Slit-Robo signaling has been linked to roles in neurogenesis, angiogenesis and cancer progression among other processes. Likewise, our mechanistic understanding of Slit-Robo signaling has progressed enormously. Here, we summarize new insights into Slit-Robo evolutionary and system-dependent diversity, receptor-ligand interactions, signaling crosstalk and receptor activation.

  20. Angle extended linear MEMS scanning system for 3D laser vision sensor

    NASA Astrophysics Data System (ADS)

    Pang, Yajun; Zhang, Yinxin; Yang, Huaidong; Zhu, Pan; Gai, Ye; Zhao, Jian; Huang, Zhanhua

    2016-09-01

    Scanning system is often considered as the most important part for 3D laser vision sensor. In this paper, we propose a method for the optical system design of angle extended linear MEMS scanning system, which has features of huge scanning degree, small beam divergence angle and small spot size for 3D laser vision sensor. The principle of design and theoretical formulas are derived strictly. With the help of software ZEMAX, a linear scanning optical system based on MEMS has been designed. Results show that the designed system can extend scanning angle from ±8° to ±26.5° with a divergence angle small than 3.5 mr, and the spot size is reduced for 4.545 times.

  1. Real-time prompt γ monitoring in spot-scanning proton therapy using imaging through a knife-edge-shaped slit.

    PubMed

    Bom, Victor; Joulaeizadeh, Leila; Beekman, Freek

    2012-01-21

    In this paper we report on Monte Carlo simulations to investigate real-time monitoring of the track depth profile in particle therapy by measuring prompt gamma ray emissions: a high sensitivity imaging system employing a knife-edge-shaped slit combined with a position-sensitive gamma detector was evaluated. Calculations to test this new concept were performed for a head-sized software phantom. Clear spatial correlation is shown between the distribution of gamma rays detected with energies above 1.5 MeV and the distribution of prompt gamma rays emitted from the phantom. The number of neutrons originating from nuclear reactions in the phantom that are detected at these high energies is small. Most importantly it is shown that under common therapy conditions enough data may be collected during one spot-step (of the order of 10 ms) to locate the distal dose edge with a 1σ accuracy of better than 1 mm. This indicates that simple slit cameras have high potential for accurate real-time particle therapy adjustment and may become a practical way to improve particle therapy accuracy.

  2. Real-time prompt gamma monitoring in spot-scanning proton therapy using imaging through a knife-edge-shaped slit

    NASA Astrophysics Data System (ADS)

    Bom, Victor; Joulaeizadeh, Leila; Beekman, Freek

    2012-01-01

    In this paper we report on Monte Carlo simulations to investigate real-time monitoring of the track depth profile in particle therapy by measuring prompt gamma ray emissions: a high sensitivity imaging system employing a knife-edge-shaped slit combined with a position-sensitive gamma detector was evaluated. Calculations to test this new concept were performed for a head-sized software phantom. Clear spatial correlation is shown between the distribution of gamma rays detected with energies above 1.5 MeV and the distribution of prompt gamma rays emitted from the phantom. The number of neutrons originating from nuclear reactions in the phantom that are detected at these high energies is small. Most importantly it is shown that under common therapy conditions enough data may be collected during one spot-step (of the order of 10 ms) to locate the distal dose edge with a 1σ accuracy of better than 1 mm. This indicates that simple slit cameras have high potential for accurate real-time particle therapy adjustment and may become a practical way to improve particle therapy accuracy.

  3. Simple linear models of scanning impedance imaging for fast reconstruction of relative conductivity of biological samples.

    PubMed

    Oliphant, Travis E; Liu, Hongze; Hawkins, Aaron R; Schultz, Stephen M

    2006-11-01

    Scanning impedance imaging (SH) uses a noncontacting electrical probe held at a known voltage and scanned over a thin sample on a ground plane in a conductive medium to obtain images of current. The current image is related in a nonlinear way to the conductivity of the sample. This paper develops the theory behind SII showing how the measured current relates to the desired conductivity. Also included is the development of a simplified, linear model that is effective in explaining many of the experimental results. Good agreement of the linear model with step-response data over an insulator is shown. The linear model shows that the current is a blurred version of the conductivity. Simple deblurring methods can, therefore, be applied to obtain relative conductivity images from the raw current data. Raw SII data from a flower-petal and a leaf sample are shown as well as relative conductivity images deblurred using the linear model.

  4. Linear optical characterization of transparent thin films by the Z-scan technique.

    PubMed

    Boudebs, Georges; Fedus, Kamil

    2009-07-20

    We report experimental characterization of a very small rectangular phase shift (<0.3 rad) obtained from the far-field diffraction patterns using a closed aperture Z-scan technique. The numerical simulations as well as the experimental results reveal a peak-valley configuration in the far-field normalized transmittance, allowing us to determine the sign of the dephasing. The conditions necessary to obtain useful Z-scan traces are discussed. We provide simple linear expressions relating the measured signal to the phase shift. A very good agreement between calculated and experimental Z-scan profiles validates our approach. We show that a very well known nonlinear characterization technique can be extended for linear optical parameter estimation (as refractive index or thickness).

  5. An Airy beam as a self-similar solution to the problem of slit laser beam propagation in a linear medium and in a photorefractive crystal with diffusion nonlinearity

    SciTech Connect

    Makarov, V A; Petnikova, V M; Shuvalov, V V

    2013-10-31

    We have analysed self-similar solutions to the propagation problem of a slit beam with a plane wavefront in a linear medium and in a photorefractive crystal with diffusion nonlinearity. It is shown that in the latter case, despite the presence of the nonlinear term in the wave equation, the linear superposition principle holds true for the solutions of this class due to saturation. At the same time, the mirror symmetry violation of the wave equation for the transverse coordinate in the nonlinear case and the requirement to the spatial localisation modify one of the localised partial solutions (Airy beam) to the corresponding linear problem and prohibit the existence of other solutions of this class. (laser beams)

  6. Breadboard linear array scan imager using LSI solid-state technology

    NASA Technical Reports Server (NTRS)

    Tracy, R. A.; Brennan, J. A.; Frankel, D. G.; Noll, R. E.

    1976-01-01

    The performance of large scale integration photodiode arrays in a linear array scan (pushbroom) breadboard was evaluated for application to multispectral remote sensing of the earth's resources. The technical approach, implementation, and test results of the program are described. Several self scanned linear array visible photodetector focal plane arrays were fabricated and evaluated in an optical bench configuration. A 1728-detector array operating in four bands (0.5 - 1.1 micrometer) was evaluated for noise, spectral response, dynamic range, crosstalk, MTF, noise equivalent irradiance, linearity, and image quality. Other results include image artifact data, temporal characteristics, radiometric accuracy, calibration experience, chip alignment, and array fabrication experience. Special studies and experimentation were included in long array fabrication and real-time image processing for low-cost ground stations, including the use of computer image processing. High quality images were produced and all objectives of the program were attained.

  7. A simple device to couple linear array transducers to neonate heads for ultrasonic scanning of the brain.

    PubMed

    Smith, W L; Franklin, T D; Katakura, K; Patrick, J T; Fry, F J; Eggleton, R C

    1980-12-01

    A plastisol coupler has been designed that improves acoustical coupling for linear array ultrasound transducers. This device improves both ease in scanning and image quality in real-time scanning of the infant brain.

  8. Handheld Thermoacoustic Scanning System Based on a Linear-array Transducer.

    PubMed

    Ji, Zhong; Ding, Wenzheng; Ye, Fanghao; Lou, Cunguang

    2016-07-01

    To receive the information necessary for imaging, traditional microwave-induced thermoacoustic imaging systems (MITISs) use a type of circular-scanning mode using single or arc detectors. However, the use of MITISs for body scanning is complicated by restrictions in space and imaging time. A linear-array detector, the most widely used transducer in medical ultrasound imaging systems for body scanning, is a possible alternative to MITISs for scanning biological tissues, such as from the breast or limbs. In this paper, a handheld MITIS, based on a linear-array detector and a multiple data acquisition system, is described, and the capacity of the system is explored experimentally. First, the vertical and lateral resolution of the system is discussed. Next, real-time imaging of a moving object, obtained with an image capture rate of 20 frame/s, is described. Finally, a phantom experiment is detailed, investigating the overall imaging capability. The results show that this system achieves rapid scanning with a large field of view. The system has the obvious advantages of being handheld, not using coupled fluids, and achieving real-time imaging with a large field of view, which make this MITIS more suitable for clinical applications. © The Author(s) 2015.

  9. Slit Wheel Repeatability

    NASA Astrophysics Data System (ADS)

    DiFelice, Audrey

    2013-10-01

    Test the repeatibility of the slit wheel by taking a sequence of comparison lamp spectra with grating G230MB {2697} and the three smallest long slits {52X0.2, 52X0.1, and 52X0.05}. This is a clone of Cycle 20 Program 13140.

  10. Slit Wheel Repeatability

    NASA Astrophysics Data System (ADS)

    Long, Chris

    2011-10-01

    Test the repeatibility of the slit wheel by taking a sequence of comparison lamp spectra with grating G230MB {2697} and the three smallest long slits {52X0.2, 52X0.1, and 52X0.05}. This is a clone of Cycle 18 Program 12410.

  11. Slit Wheel Repeatability

    NASA Astrophysics Data System (ADS)

    DiFelice, Audrey

    2012-10-01

    Test the repeatibility of the slit wheel by taking a sequence of comparison lamp spectra with grating G230MB {2697} and the three smallest long slits {52X0.2, 52X0.1, and 52X0.05}. This is a clone of Cycle 19 Program 12771.

  12. Non-Linear Structural Dynamics Characterization using a Scanning Laser Vibrometer

    NASA Technical Reports Server (NTRS)

    Pai, P. F.; Lee, S.-Y.

    2003-01-01

    This paper presents the use of a scanning laser vibrometer and a signal decomposition method to characterize non-linear dynamics of highly flexible structures. A Polytec PI PSV-200 scanning laser vibrometer is used to measure transverse velocities of points on a structure subjected to a harmonic excitation. Velocity profiles at different times are constructed using the measured velocities, and then each velocity profile is decomposed using the first four linear mode shapes and a least-squares curve-fitting method. From the variations of the obtained modal \\ielocities with time we search for possible non-linear phenomena. A cantilevered titanium alloy beam subjected to harmonic base-excitations around the second. third, and fourth natural frequencies are examined in detail. Influences of the fixture mass. gravity. mass centers of mode shapes. and non-linearities are evaluated. Geometrically exact equations governing the planar, harmonic large-amplitude vibrations of beams are solved for operational deflection shapes using the multiple shooting method. Experimental results show the existence of 1:3 and 1:2:3 external and internal resonances. energy transfer from high-frequency modes to the first mode. and amplitude- and phase- modulation among several modes. Moreover, the existence of non-linear normal modes is found to be questionable.

  13. Single Analyzer Precursor Ion Scans in a Linear Quadrupole Ion Trap Using Orthogonal Double Resonance Excitation

    NASA Astrophysics Data System (ADS)

    Snyder, Dalton T.; Cooks, R. Graham

    2017-09-01

    Reported herein is a simple method of performing single analyzer precursor ion scans in a linear quadrupole ion trap using orthogonal double resonance excitation. A first supplementary AC signal applied to the y electrodes is scanned through ion secular frequencies in order to mass-selectively excite precursor ions while, simultaneously, a second fixed-frequency AC signal is applied orthogonally on the x electrodes in order to eject product ions of selected mass-to-charge ratios towards the detector. The two AC signals are applied orthogonally so as to preclude the possibility of (1) inadvertently ejecting precursor ions into the detector, which results in artifact peaks, and (2) prevent beat frequencies on the x electrodes from ejecting ions off-resonance. Precursor ion scans are implemented while using the inverse Mathieu q scan for easier mass calibration. The orthogonal double resonance experiment results in single ion trap precursor scans with far less intense artifact peaks than when both AC signals are applied to the same electrodes, paving the way for implementation of neutral loss scanning in single ion trap mass spectrometers. [Figure not available: see fulltext.

  14. Scanning differential polarization microscope: Its use to image linear and circular differential scattering

    SciTech Connect

    Mickols, W.; Maestre, M.F.

    1988-06-01

    A differential polarization microscope that couples the sensitivity of single-beam measurement of circular dichroism and circular differential scattering with the simultaneous measurement of linear dichroism and linear differential scattering has been developed. The microscope uses a scanning microscope stage and single-point illumination to give the very shallow depth of field found in confocal microscopy. This microscope can operate in the confocal mode as well as in the near confocal condition that can allow one to program the coherence and spatial resolution of the microscope. This microscope has been used to study the change in the structure of chromatin during the development of sperm in Drosophila.

  15. A novel method of drift-scanning stars suppression based on the standardized linear filter

    NASA Astrophysics Data System (ADS)

    Lin, Jianlin; Ping, Xijian; Hou, Guanghua; Ma, Debao

    2011-11-01

    A large number of stars in the drift-scanning star image have interfered with the detection of small target, this paper proposes an adaptive linear filtering method to achieve the small target detection by suppressing the stars. Firstly, the characteristics of stars, interest target and noise three different representative objects in the star image are analyzed, then the standardized linear filter is constructed to suppress the stars. For the purpose of decreasing the influence region of stars filtering uniformly, a gradient linear filter is constructed to modify the stars suppression method with the standardized linear filter. Then the filter parameter selection method is given. Finally, a multi-frame target track experiment on the real drift-scanning data is made to testify the validity of the proposed method. With the processing results of different methods, it has been showed that the proposed method for suppressing stars with different length and lean angle has a better effect, higher robustness and easier application than the others.

  16. Micromechanical slit positioning system as a transmissive spatial light modulator

    NASA Astrophysics Data System (ADS)

    Riesenberg, Rainer

    2001-11-01

    Micro-slits have been prepared with a slit-width and a slit- length of 2 ... 1000 micrometers . Linear and two-dimensional arrays up to 10 x 110 slits have been developed and completed with a piezo-actuator for shifting. This system is a so-called mechanical slit positioning system. The light is switched by simple one- or two-dimensional displacement of coded slit masks in a one- or two-layer architecture. The slit positioning system belongs to the transmissive class of MEMS-based spatial light modulators (SLM). It has fundamental advantages for optical contrast and also can be used in the full spectral region. Therefore transmissive versions of SLM should be a future solution. Instrument architectures based on the slit positioning system can increase the resolution by subpixel generation, the throughput by HADAMARD transform mode, or select objects for multi-object-spectroscopy. The linear slit positioning system was space qualified within an advanced micro- spectrometer. A NIR multi-object-spectrometer for the Next Generation Space Telescope (NGST) is based on a field selector for selecting objects. The field selector is a SLM, which could be implemented by a slit positioning system.

  17. Spectral manifestations of polarization action of narrow slit

    NASA Astrophysics Data System (ADS)

    Felde, Ch. V.; Oleksyuk, M. V.; Polyanskii, P. V.

    2013-06-01

    Experimental study of quasimonochromatic and polychromatic ("white-light") radiation, that diffracts on very narrow (in order of several wavelength) slit in metallic screen is represented. It is shown that for monochromatic light slit acts similarly to linear analyzer. And for polychromatic light polarization action of a slit is accompanied with a spectral effect, viz. considerable predomination of blue component in total radiation. The chromascopic technique is applied for analyzing this spectral effect.

  18. Edge guided image reconstruction in linear scan CT by weighted alternating direction TV minimization.

    PubMed

    Cai, Ailong; Wang, Linyuan; Zhang, Hanming; Yan, Bin; Li, Lei; Xi, Xiaoqi; Li, Jianxin

    2014-01-01

    Linear scan computed tomography (CT) is a promising imaging configuration with high scanning efficiency while the data set is under-sampled and angularly limited for which high quality image reconstruction is challenging. In this work, an edge guided total variation minimization reconstruction (EGTVM) algorithm is developed in dealing with this problem. The proposed method is modeled on the combination of total variation (TV) regularization and iterative edge detection strategy. In the proposed method, the edge weights of intermediate reconstructions are incorporated into the TV objective function. The optimization is efficiently solved by applying alternating direction method of multipliers. A prudential and conservative edge detection strategy proposed in this paper can obtain the true edges while restricting the errors within an acceptable degree. Based on the comparison on both simulation studies and real CT data set reconstructions, EGTVM provides comparable or even better quality compared to the non-edge guided reconstruction and adaptive steepest descent-projection onto convex sets method. With the utilization of weighted alternating direction TV minimization and edge detection, EGTVM achieves fast and robust convergence and reconstructs high quality image when applied in linear scan CT with under-sampled data set.

  19. Slit injection device

    DOEpatents

    Alger, Terry W.; Schlitt, Leland G.; Bradley, Laird P.

    1976-06-15

    A laser cavity electron beam injection device provided with a single elongated slit window for passing a suitably shaped electron beam and means for varying the current density of the injected electron beam.

  20. A Fourier Transform Spectrometer Based on an Electrothermal MEMS Mirror with Improved Linear Scan Range.

    PubMed

    Wang, Wei; Chen, Jiapin; Zivkovic, Aleksandar S; Xie, Huikai

    2016-09-29

    A Fourier transform spectrometer (FTS) that incorporates a closed-loop controlled, electrothermally actuated microelectromechanical systems (MEMS) micromirror is proposed and experimentally verified. The scan range and the tilting angle of the mirror plate are the two critical parameters for MEMS-based FTS. In this work, the MEMS mirror with a footprint of 4.3 mm × 3.1 mm is based on a modified lateral-shift-free (LSF) bimorph actuator design with large piston and reduced tilting. Combined with a position-sensitive device (PSD) for tilt angle sensing, the feedback controlled MEMS mirror generates a 430 µm stable linear piston scan with the mirror plate tilting angle less than ±0.002°. The usable piston scan range is increased to 78% of the MEMS mirror's full scan capability, and a spectral resolution of 0.55 nm at 531.9 nm wavelength, has been achieved. It is a significant improvement compared to the prior work.

  1. A Fourier Transform Spectrometer Based on an Electrothermal MEMS Mirror with Improved Linear Scan Range

    PubMed Central

    Wang, Wei; Chen, Jiapin; Zivkovic, Aleksandar. S.; Xie, Huikai

    2016-01-01

    A Fourier transform spectrometer (FTS) that incorporates a closed-loop controlled, electrothermally actuated microelectromechanical systems (MEMS) micromirror is proposed and experimentally verified. The scan range and the tilting angle of the mirror plate are the two critical parameters for MEMS-based FTS. In this work, the MEMS mirror with a footprint of 4.3 mm × 3.1 mm is based on a modified lateral-shift-free (LSF) bimorph actuator design with large piston and reduced tilting. Combined with a position-sensitive device (PSD) for tilt angle sensing, the feedback controlled MEMS mirror generates a 430 µm stable linear piston scan with the mirror plate tilting angle less than ±0.002°. The usable piston scan range is increased to 78% of the MEMS mirror’s full scan capability, and a spectral resolution of 0.55 nm at 531.9 nm wavelength, has been achieved. It is a significant improvement compared to the prior work. PMID:27690047

  2. Relating Linear and Volumetric Variables Through Body Scanning to Improve Human Interfaces in Space

    NASA Technical Reports Server (NTRS)

    Margerum, Sarah E.; Ferrer, Mike A.; Young, Karen S.; Rajulu, Sudhakar

    2010-01-01

    Designing space suits and vehicles for the diverse human population present unique challenges for the methods of traditional anthropometry. Space suits are bulky and allow the operator to shift position within the suit and inhibit the ability to identify body landmarks. Limited suit sizing options also cause variability in fit and performance between similarly sized individuals. Space vehicles are restrictive in volume in both the fit and the ability to collect data. NASA's Anthropometric and Biomechanics Facility (ABF) has utilized 3D scanning to shift from traditional linear anthropometry to explore and examine volumetric capabilities to provide anthropometric solutions for design. Overall, the key goals are to improve the human-system performance and develop new processes to aid in the design and evaluation of space systems. Four case studies are presented that illustrate the shift from purely linear analyses to an augmented volumetric toolset to predict and analyze the human within the space suit and vehicle. The first case study involves the calculation of maximal head volume to estimate total free volume in the helmet for proper air exchange. Traditional linear measurements resulted in an inaccurate representation of the head shape, yet limited data exists for the determination of a large head volume. Steps were first taken to identify and classify a maximum head volume and the resulting comparisons to the estimate are presented in this paper. This study illustrates the gap between linear components of anthropometry and the need for overall volume metrics in order to provide solutions. A second case study examines the overlay of the space suit scans and components onto scanned individuals to quantify fit and clearance to aid in sizing the suit to the individual. Restrictions in space suit size availability present unique challenges to optimally fit the individual within a limited sizing range while maintaining performance. Quantification of the clearance and

  3. Time-resolved step-scan infrared imaging system utilizing a linear array detector.

    PubMed

    Sugiyama, Hiroshi; Koshoubu, Jun; Kashiwabara, Seiichi; Nagoshi, Toshiyuki; Larsen, Richard A; Akao, Kenichi

    2008-01-01

    A time-resolved infrared (IR) imaging system combined with a multichannel IR microscope, which utilizes a 16 channel linear array (LA) detector, and step-scan Fourier transform infrared (FT-IR) microscope was developed. The LA detector integrates a readout circuit on each detector element, so the detected signals can be read simultaneously. Thus, this system can perform high speed imaging using the step-scan method, similar to a single channel detector. To verify the capabilities of this system, a reflective sample was examined whose position was altered using a piezo actuator activated by an alternating voltage. In addition, the localization of relaxation dynamics for the liquid crystal (LC) molecules in an LC cell under oscillating electric field conditions was detected by this system.

  4. Scanning Electron Microscope Calibration Using a Multi-Image Non-Linear Minimization Process

    NASA Astrophysics Data System (ADS)

    Cui, Le; Marchand, Éric

    2015-04-01

    A scanning electron microscope (SEM) calibrating approach based on non-linear minimization procedure is presented in this article. A part of this article has been published in IEEE International Conference on Robotics and Automation (ICRA), 2014. . Both the intrinsic parameters and the extrinsic parameters estimations are achieved simultaneously by minimizing the registration error. The proposed approach considers multi-images of a multi-scale calibration pattern view from different positions and orientations. Since the projection geometry of the scanning electron microscope is different from that of a classical optical sensor, the perspective projection model and the parallel projection model are considered and compared with distortion models. Experiments are realized by varying the position and the orientation of a multi-scale chessboard calibration pattern from 300× to 10,000×. The experimental results show the efficiency and the accuracy of this approach.

  5. Differential linear scan voltammetry: analytical performance in comparison with pulsed voltammetry techniques.

    PubMed

    Sheth, Disha B; Gratzl, Miklós

    2013-06-01

    We report here on differential linear scan voltammetry, DLSV, that combines the working principles of linear scan voltammetry, LSV, and the numerous existing pulsed voltammetry techniques. DLSV preserves the information from continuous interrogation in voltage and high accuracy that LSV provides about electrochemical processes, and the much better sensitivity of differential pulsed techniques. DLSV also minimizes the background current compared to both LSV and pulsed voltammetry. An early version of DLSV, derivative stationary electrode polarography, DSEP, had been proposed in the 1960s but soon abandoned in favor of the emerging differential pulsed techniques. Relative to DSEP, DLSV takes advantage of the flexibility of discrete smoothing differentiation that was not available to early investigators. Also, DSEP had been explored in pure solutions and with reversible electrochemical reactions. DLSV is tested in this work in more challenging experimental contexts: the measurement of oxygen with a carbon fiber microelectrode in buffer, and with a gold microdisc electrode exposed to a live biological preparation. This work compares the analytical performance of DLSV and square wave voltammetry, the most popular pulsed voltammetry technique.

  6. SCAN+

    SciTech Connect

    Kenneth Krebs, John Svoboda

    2009-11-01

    SCAN+ is a software application specifically designed to control the positioning of a gamma spectrometer by a two dimensional translation system above spent fuel bundles located in a sealed spent fuel cask. The gamma spectrometer collects gamma spectrum information for the purpose of spent fuel cask fuel loading verification. SCAN+ performs manual and automatic gamma spectrometer positioning functions as-well-as exercising control of the gamma spectrometer data acquisitioning functions. Cask configuration files are used to determine the positions of spent fuel bundles. Cask scanning files are used to determine the desired scan paths for scanning a spent fuel cask allowing for automatic unattended cask scanning that may take several hours.

  7. The fundus slit lamp.

    PubMed

    Gellrich, Marcus-Matthias

    2015-01-01

    Fundus biomicroscopy with the slit lamp as it is practiced widely nowadays was not established until the 1980-es with the introduction of the Volk lenses +90 and +60D. Thereafter little progress has been made in retinal imaging with the slit lamp. It is the aim of this paper to fully exploit the potential of a video slit lamp for fundus documentation by using easily accessible additions. Suitable still images are easily retrieved from videorecordings of slit lamp examinations. The effects of changements in the slit lamp itself (slit beam and apertures) and its examination equipment (converging lenses from +40 to +90D) on quality and spectrum of fundus images are demonstrated. Imaging software is applied for reconstruction of larger fundus areas in a mosaic pattern (Hugin®) and to perform the flicker test in order to visualize changes in the same fundus area at different points of time (Power Point®). The three lenses +90/+60/+40D are a good choice for imaging the whole spectrum of retinal diseases. Displacement of the oblique slit light can be used to assess changes in the surface profile of the inner retina which occurs e.g. in macular holes or pigment epithelial detachment. The mosaic function in its easiest form (one strip macula adapted to one strip with the optic disc) provides an overview of the posterior pole comparable to a fundus camera's image. A reconstruction of larger fundus areas is feasible for imaging in vitreoretinal surgery or occlusive vessel disease. The flicker test is a fine tool for monitoring progressive glaucoma by changes in the optic disc, and it is also a valuable diagnostic tool in macular disease. Nearly all retinal diseases can be imaged with the slit lamp - irrespective whether they affect the posterior pole, mainly the optic nerve or the macula, the whole retina or only its periphery. Even a basic fundus controlled perimetry is possible. Therefore fundus videography with the slit lamp is a worthwhile approach especially for the

  8. Automatic correction of diffraction pattern shift in a pushbroom hyperspectral imager with a piezoelectric internal line-scanning unit

    NASA Astrophysics Data System (ADS)

    Abdo, Mohammad; Förster, Erik; Bohnert, Patrick; Stürmer, Moritz; Badilita, Vlad; Brunner, Robert; Wallrabe, Ulrike; Korvink, Jan G.

    2017-02-01

    Pushbroom hyperspectral imaging systems require relative motion with respect to the target for hyperspectral data acquisition by means of spatial scanning, which increases the equipment cost and limits the application scenarios. We address this by introducing a pushbroom system with an internal line-scanning unit consisting of a slit aperture mounted on a piezoelectric linear motor. Different slit positions have tilted incidence angles at the grating, resulting in shifts of diffraction patterns relative to the imaging sensor. We demonstrate a method to compensate this shift by using a rotating arm controlled by a stepper motor to reposition the camera based on slit position.

  9. SLIT ADJUSTMENT CLAMP

    DOEpatents

    McKenzie, K.R.

    1959-07-01

    An electrode support which permits accurate alignment and adjustment of the electrode in a plurality of planes and about a plurality of axes in a calutron is described. The support will align the slits in the electrode with the slits of an ionizing chamber so as to provide for the egress of ions. The support comprises an insulator, a leveling plate carried by the insulator and having diametrically opposed attaching screws screwed to the plate and the insulator and diametrically opposed adjusting screws for bearing against the insulator, and an electrode associated with the plate for adjustment therewith.

  10. Non-linear optical flow cytometry using a scanned, Bessel beam light-sheet.

    PubMed

    Collier, Bradley B; Awasthi, Samir; Lieu, Deborah K; Chan, James W

    2015-05-29

    Modern flow cytometry instruments have become vital tools for high-throughput analysis of single cells. However, as issues with the cellular labeling techniques often used in flow cytometry have become more of a concern, the development of label-free modalities for cellular analysis is increasingly desired. Non-linear optical phenomena (NLO) are of growing interest for label-free analysis because of the ability to measure the intrinsic optical response of biomolecules found in cells. We demonstrate that a light-sheet consisting of a scanned Bessel beam is an optimal excitation geometry for efficiently generating NLO signals in a microfluidic environment. The balance of photon density and cross-sectional area provided by the light-sheet allowed significantly larger two-photon fluorescence intensities to be measured in a model polystyrene microparticle system compared to measurements made using other excitation focal geometries, including a relaxed Gaussian excitation beam often used in conventional flow cytometers.

  11. In situ azimuthal rotation device for linear dichroism measurements in scanning transmission x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Hernández-Cruz, D.; Hitchcock, A. P.; Tyliszczak, T.; Rousseau, M.-E.; Pézolet, M.

    2007-03-01

    A novel miniature rotation device used in conjunction with a scanning transmission x-ray microscope is described. It provides convenient in situ sample rotation to enable measurements of linear dichroism at high spatial resolution. The design, fabrication, and mechanical characterization are presented. This device has been used to generate quantitative maps of the spatial distribution of the orientation of proteins in several different spider and silkworm silks. Specifically, quantitative maps of the dichroic signal at the C 1s→π*amide transition in longitudinal sections of the silk fibers give information about the spatial orientation, degree of alignment, and spatial distribution of protein peptide bonds. A new approach for analyzing the dichroic signal to extract orientation distributions, in addition to magnitudes of aligned components, is presented and illustrated with results from Nephila clavipes dragline spider silk measured using the in situ rotation device.

  12. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    NASA Astrophysics Data System (ADS)

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  13. Digital radiography of the chest by self-scanning linear diode arrays.

    PubMed

    Slasky, B S; Sashin, D; Horton, J A; Sternglass, E J; Bron, K M; Deutsch, M; Herron, J M; Kennedy, W H; Boyer, J W; Girdany, B R

    1987-01-01

    Diode array digital radiography DADR is a method of radiographic imaging that combines the advantages of computer technology with self-scanning linear diode arrays. These digital images are superior to those obtained by film in recording and displaying information in the lightest and the darkest areas of the film, resulting in a balanced image of the entire thorax without compromising detail, and at reduced radiation dose. This is a direct result of the wide dynamic range, high contrast sensitivity, fiber optic coupling, small diode size, short exposure time, and rejection of scattered x-rays of the system coupled with digital post-processing enhancement of the image displayed at 1024 X 1024 pixels.

  14. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    PubMed Central

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-01-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

  15. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

    PubMed

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  16. Non-Linear Optical Flow Cytometry Using a Scanned, Bessel Beam Light-Sheet

    PubMed Central

    Collier, Bradley B.; Awasthi, Samir; Lieu, Deborah K.; Chan, James W.

    2015-01-01

    Modern flow cytometry instruments have become vital tools for high-throughput analysis of single cells. However, as issues with the cellular labeling techniques often used in flow cytometry have become more of a concern, the development of label-free modalities for cellular analysis is increasingly desired. Non-linear optical phenomena (NLO) are of growing interest for label-free analysis because of the ability to measure the intrinsic optical response of biomolecules found in cells. We demonstrate that a light-sheet consisting of a scanned Bessel beam is an optimal excitation geometry for efficiently generating NLO signals in a microfluidic environment. The balance of photon density and cross-sectional area provided by the light-sheet allowed significantly larger two-photon fluorescence intensities to be measured in a model polystyrene microparticle system compared to measurements made using other excitation focal geometries, including a relaxed Gaussian excitation beam often used in conventional flow cytometers. PMID:26021750

  17. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    SciTech Connect

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  18. 3-D ultrasonic strain imaging based on a linear scanning system.

    PubMed

    Huang, Qinghua; Xie, Bo; Ye, Pengfei; Chen, Zhaohong

    2015-02-01

    This paper introduces a 3-D strain imaging method based on a freehand linear scanning mode. We designed a linear sliding track with a position sensor and a height-adjustable holder to constrain the movement of an ultrasound probe in a freehand manner. When moving the probe along the sliding track, the corresponding positional measures for the probe are transmitted via a wireless communication module based on Bluetooth in real time. In a single examination, the probe is scanned in two sweeps in which the height of the probe is adjusted by the holder to collect the pre- and postcompression radio-frequency echoes, respectively. To generate a 3-D strain image, a volume cubic in which the voxels denote relative strains for tissues is defined according to the range of the two sweeps. With respect to the post-compression frames, several slices in the volume are determined and the pre-compression frames are re-sampled to precisely correspond to the post-compression frames. Thereby, a strain estimation method based on minimizing a cost function using dynamic programming is used to obtain the 2-D strain image for each pair of frames from the re-sampled pre-compression sweep and the post-compression sweep, respectively. A software system is developed for volume reconstruction, visualization, and measurement of the 3-D strain images. The experimental results show that high-quality 3-D strain images of phantom and human tissues can be generated by the proposed method, indicating that the proposed system can be applied for real clinical applications (e.g., musculoskeletal assessments).

  19. Autoregressive linear least square single scanning electron microscope image signal-to-noise ratio estimation.

    PubMed

    Sim, Kok Swee; NorHisham, Syafiq

    2016-11-01

    A technique based on linear Least Squares Regression (LSR) model is applied to estimate signal-to-noise ratio (SNR) of scanning electron microscope (SEM) images. In order to test the accuracy of this technique on SNR estimation, a number of SEM images are initially corrupted with white noise. The autocorrelation function (ACF) of the original and the corrupted SEM images are formed to serve as the reference point to estimate the SNR value of the corrupted image. The LSR technique is then compared with the previous three existing techniques known as nearest neighbourhood, first-order interpolation, and the combination of both nearest neighborhood and first-order interpolation. The actual and the estimated SNR values of all these techniques are then calculated for comparison purpose. It is shown that the LSR technique is able to attain the highest accuracy compared to the other three existing techniques as the absolute difference between the actual and the estimated SNR value is relatively small. SCANNING 38:771-782, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  20. Elimination Voltammetry with Linear Scan as a New Detection Method for DNA Sensors

    PubMed Central

    Trnkova, Libuse; Jelen, Frantisek; Petrlova, Jitka; Adam, Vojtech; Potesil, David; Kizek, Rene

    2005-01-01

    The paper describes successful coupling of adsorptive transfer stripping (AdTS) and elimination voltammetry with linear scan (EVLS) for the resolution of reduction signals of cytosine (C) and adenine (A) residues in hetero-oligodeoxynucleotides (ODNs). Short ODNs (9-mers and 20-mers) were adsorbed from a small volume on a hanging mercury drop electrode (HMDE). After washing of the ODN-modified electrode by water and its transferring to an electrochemical cell, voltammetric curves were measured. The AdTS EVLS was able to determine of C/A ratio of ODNs through the elimination function conserving the diffusion current component and eliminating kinetic and charging current components. This function, which provides the elimination signal in a peak-counterpeak form, increased the current sensitivity for A and C resolution, and for the recognition of bases sequences in ODN chains. Optimal conditions of elimination experiments such as pH, time of adsorption, and scan rate were found. The combination of EVLS with AdTS procedure can be considered as a new detection method in a DNA sensor.

  1. Filtration to reduce paediatric dose for a linear slot-scanning digital X-ray machine.

    PubMed

    Perks, T D; Dendere, R; Irving, B; Hartley, T; Scholtz, P; Lawson, A; Trauernicht, C; Steiner, S; Douglas, T S

    2015-12-01

    This paper describes modelling, application and validation of a filtration technique for a linear slot-scanning digital X-ray system to reduce radiation dose to paediatric patients while preserving diagnostic image quality. A dose prediction model was implemented, which calculates patient entrance doses using variable input parameters. Effective dose is calculated using a Monte Carlo simulation. An added filter of 1.8-mm aluminium was predicted to lower the radiation dose significantly. An objective image quality study was conducted using detective quantum efficiency (DQE). The PTW Normi 4FLU test phantom was used for quantitative assessment, showing that image contrast and spatial resolution were maintained with the proposed filter. A paediatric cadaver full-body imaging trial assessed the diagnostic quality of the images and measured the dose reduction using a 1.8-mm aluminium filter. Assessment by radiologists indicated that diagnostic quality was maintained with the added filtration, despite a reduction in DQE. A new filtration technique for full-body paediatric scanning on the Lodox Statscan has been validated, reducing entrance dose for paediatric patients by 36 % on average and effective dose by 27 % on average, while maintaining image quality.

  2. Slit-lamp exam (image)

    MedlinePlus

    A slit-lamp, which is a specialized magnifying microscope, is used to examine the structures of the eye (including the cornea, iris, vitreous, and retina). The slit-lamp is used to examine, treat (with a laser), ...

  3. Cleaved Slit directs embryonic muscles

    PubMed Central

    Ordan, Elly; Volk, Talila

    2015-01-01

    The formation of functional musculoskeletal system relies on proper connectivity between muscles and their corresponding tendon cells. In Drosophila, larval muscles are born during early embryonic stages, and elongate toward tendons that are embedded within the ectoderm in later. The Slit/Robo signaling pathway had been implicated in the process of muscle elongation toward tendons. Here we discuss our recent findings regarding the critical contribution of Slit cleavage for immobilization and stabilization of the Slit signal on the tendon cells. Slit cleavage produces 2 polypeptides, the N-terminal Slit-N, which is extremely stable, undergoes oligomerization, and associates with the tendon cell surfaces, and the C-terminal Slit-C, which rapidly degrades. Slit cleavage leads to immobilization of Slit signaling on tendons, leading to a short-range repulsion, which eventually arrest further muscle elongation. Robo2, which is co-expressed with Slit by the tendon cells facilitates Slit cleavage. This activity does not require the cytoplasmic signaling domain of Robo2. We suggest that Robo2-dependent Slit cleavage, and the formation of Slit-N oligomers on the tendon cell surfaces direct muscle elongation, and provide a stop signal for the approaching muscle, through binding to Robo and Robo3 receptors expressed by the muscles. PMID:26554435

  4. Power-efficient nonreciprocal interferometer and linear-scanning fiber-optic catheter for optical coherence tomography.

    PubMed

    Bouma, B E; Tearney, G J

    1999-04-15

    A nonreciprocal fiber-optic interferometer is demonstrated in an optical coherence tomography (OCT) system. The increased power efficiency of this system provides a 4.1-dB advantage over standard Michelson implementations. In addition, a new linear-scanning fiber-optic catheter is demonstrated that avoids the rotary optical junction that is required in circumferential scanning systems. These advancements have permitted the clinical implementation of OCT imaging in the human gastrointestinal tract.

  5. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    DOE PAGES

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; ...

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, makingmore » it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.« less

  6. Laser-induced scanning tunneling microscopy: Linear excitation of the junction plasmon.

    PubMed

    Lee, Joonhee; Perdue, Shawn M; Whitmore, Desiré; Apkarian, V Ara

    2010-09-14

    We introduce the cross-polarized double-beat method for localized excitation of the junction plasmon of a scanning tunneling microscope with femtosecond laser pulses. We use two pulse trains derived from a Ti:sapphire laser operating at a repetition frequency of f(s)=76 MHz, with a relative shift between their carrier frequencies ω(a)/2π=f(s)+f(b) controlled with an acousto-optic modulator. The trains are cross-polarized and collinearly focused on the junction, ensuring constant radiation flux. The anisotropic susceptibility of the junction plasmon mixes the fields, which modulate the tunneling current at f(b) (the difference between carrier beat and repetition frequency) at base-band frequencies that can be used for direct detection of the tunneling current. The interferometric cross-correlation of the pulses and the polarization dependence of the mixing identify the coupling to the radiation to be through the coherent z-displacement of the tip plasmon. Single Ag atoms are used to demonstrate microscopy under irradiation. In the linear coupling regime, the laser-induced displacement of the plasmon is operationally indistinguishable from the mechanical displacement of the junction gap.

  7. Optimization of an adaptive SPECT system with the scanning linear estimator

    NASA Astrophysics Data System (ADS)

    Ghanbari, Nasrin; Clarkson, Eric; Kupinski, Matthew A.; Li, Xin

    2015-08-01

    The adaptive single-photon emission computed tomography (SPECT) system studied here acquires an initial scout image to obtain preliminary information about the object. Then the configuration is adjusted by selecting the size of the pinhole and the magnification that optimize system performance on an ensemble of virtual objects generated to be consistent with the scout data. In this study the object is a lumpy background that contains a Gaussian signal with a variable width and amplitude. The virtual objects in the ensemble are imaged by all of the available configurations and the subsequent images are evaluated with the scanning linear estimator to obtain an estimate of the signal width and amplitude. The ensemble mean squared error (EMSE) on the virtual ensemble between the estimated and the true parameters serves as the performance figure of merit for selecting the optimum configuration. The results indicate that variability in the original object background, noise and signal parameters leads to a specific optimum configuration in each case. A statistical study carried out for a number of objects show that the adaptive system on average performs better than its nonadaptive counterpart.

  8. Top-level design and pilot analysis of low-end CT scanners based on linear scanning for developing countries.

    PubMed

    Liu, Fenglin; Yu, Hengyong; Cong, Wenxiang; Wang, Ge

    2014-01-01

    The goal is to develop new architectures for computed tomography (CT) which are at an ultra-low-cost for developing countries, especially in rural areas. The proposed general scheme is inspired by the recently developed compressive sensing and interior tomography techniques, where the data acquisition system targets a region of interest (ROI) to acquire limited and truncated data. Similar to linear tomosynthesis, the source and detector are translated in opposite directions but in contrast to conventional tomosynthesis, our proposal is for either ROI reconstruction with one or more localized linear scans or global reconstruction by combining multiple ROI reconstructions. In other words, the popular slip ring is replaced by a translation based setup, and the instrumentation cost is reduced by a relaxation of the imaging speed requirement. The various translational scanning modes are theoretically analyzed, and the scanning parameters are optimized. The numerical simulation results from different numbers of linear scans confirm the feasibility of the proposed scheme, and suggest two preferred low-end systems for horizontal and vertical patient positions respectively. Ultra-low-cost x-ray CT is feasible with our proposed combination of linear scanning, compressive sensing, and interior tomography. The proposed architecture can be tailored into permanent, movable, or reconfigurable systems as desirable. Advanced image registration and spectral imaging features can be included as well.

  9. Slit and Robo control cardiac cell polarity and morphogenesis.

    PubMed

    Qian, Li; Liu, Jiandong; Bodmer, Rolf

    2005-12-20

    Basic aspects of heart morphogenesis involving migration, cell polarization, tissue alignment, and lumen formation may be conserved between Drosophila and humans, but little is known about the mechanisms that orchestrate the assembly of the heart tube in either organism. The extracellular-matrix molecule Slit and its Robo-family receptors are conserved regulators of axonal guidance. Here, we report a novel role of the Drosophila slit, robo, and robo2 genes in heart morphogenesis. Slit and Robo proteins specifically accumulate at the dorsal midline between the bilateral myocardial progenitors forming a linear tube. Manipulation of Slit localization or its overexpression causes disruption in heart tube alignment and assembly, and slit-deficient hearts show disruptions in cell-polarity marker localization within the myocardium. Similar phenotypes are observed when Robo and Robo2 are manipulated. Rescue experiments suggest that Slit is secreted from the myocardial progenitors and that Robo and Robo2 act in myocardial and pericardial cells, respectively. Genetic interactions suggest a cardiac morphogenesis network involving Slit/Robo, cell-polarity proteins, and other membrane-associated proteins. We conclude that Slit and Robo proteins contribute significantly to Drosophila heart morphogenesis by guiding heart cell alignment and adhesion and/or by inhibiting cell mixing between the bilateral compartments of heart cell progenitors and ensuring proper polarity of the myocardial epithelium.

  10. Assessment of cardiac single-photon emission computed tomography performance using a scanning linear observer

    SciTech Connect

    Lee, Chih-Jie; Kupinski, Matthew A.; Volokh, Lana

    2013-01-15

    Purpose: Single-photon emission computed tomography (SPECT) is widely used to detect myocardial ischemia and myocardial infarction. It is important to assess and compare different SPECT system designs in order to achieve the highest detectability of cardiac defects. Methods: Whitaker et al.'s study ['Estimating random signal parameters from noisy images with nuisance parameters: linear and scanning-linear methods,' Opt. Express 16(11), 8150-8173 (2008)] on the scanning linear observer (SLO) shows that the SLO can be used to estimate the location and size of signals. One major advantage of the SLO is that it can be used with projection data rather than with reconstruction data. Thus, this observer model assesses the overall hardware performance independent of any reconstruction algorithm. In addition, the computation time of image quality studies is significantly reduced. In this study, three systems based on the design of the GE cadmium zinc telluride-based dedicated cardiac SPECT camera Discovery 530c were assessed. This design, which is officially named the Alcyone Technology: Discovery NM 530c, was commercialized in August, 2009. The three systems, GE27, GE19, and GE13, contain 27, 19, and 13 detectors, respectively. Clinically, a human heart can be virtually segmented into three coronary artery territories: the left-anterior descending artery, left-circumflex artery, and right coronary artery. One of the most important functions of a cardiac SPECT system is to produce images from which a radiologist can accurately predict in which territory the defect exists [http://www.asnc.org/media/PDFs/PPReporting081511.pdf, Guideline from American Society of Nuclear Cardiology]. A good estimation of the extent of the defect from the projection images is also very helpful for determining the seriousness of the myocardial ischemia. In this study, both the location and extent of defects were estimated by the SLO, and the system performance was assessed by localization

  11. Assessment of cardiac single-photon emission computed tomography performance using a scanning linear observer

    PubMed Central

    Lee, Chih-Jie; Kupinski, Matthew A.; Volokh, Lana

    2013-01-01

    Purpose: Single-photon emission computed tomography (SPECT) is widely used to detect myocardial ischemia and myocardial infarction. It is important to assess and compare different SPECT system designs in order to achieve the highest detectability of cardiac defects. Methods:Whitaker ’s study [“Estimating random signal parameters from noisy images with nuisance parameters: linear and scanning-linear methods,” Opt. Express 16(11), 8150–8173 (2008)]10.1364/OE.16.008150 on the scanning linear observer (SLO) shows that the SLO can be used to estimate the location and size of signals. One major advantage of the SLO is that it can be used with projection data rather than with reconstruction data. Thus, this observer model assesses the overall hardware performance independent of any reconstruction algorithm. In addition, the computation time of image quality studies is significantly reduced. In this study, three systems based on the design of the GE cadmium zinc telluride-based dedicated cardiac SPECT camera Discovery 530c were assessed. This design, which is officially named the Alcyone Technology: Discovery NM 530c, was commercialized in August, 2009. The three systems, GE27, GE19, and GE13, contain 27, 19, and 13 detectors, respectively. Clinically, a human heart can be virtually segmented into three coronary artery territories: the left-anterior descending artery, left-circumflex artery, and right coronary artery. One of the most important functions of a cardiac SPECT system is to produce images from which a radiologist can accurately predict in which territory the defect exists [http://www.asnc.org/media/PDFs/PPReporting081511.pdf, Guideline from American Society of Nuclear Cardiology]. A good estimation of the extent of the defect from the projection images is also very helpful for determining the seriousness of the myocardial ischemia. In this study, both the location and extent of defects were estimated by the SLO, and the system performance was assessed by

  12. Effect of linear alkyl benzene sulfonate in skin of fish fingerlings (Cirrhina mrigala): observations with scanning electron microscope

    SciTech Connect

    Misra, V.; Chawla, G.; Kumar, V.; Lal, H.; Viswanathan, P.N.

    1987-04-01

    Pathomorphological changes in the skin was noticed under the scanning electron microscope in fish fingerlings (Cirrhina mrigala) exposed to 0.005 ppm (25% of the LC50) concentration to linear alkyl benzene sulfonate. The epithelial cells present in the epidermis of the skin were found to secrete more mucus with linear alkyl benzene sulfonate (LAS) than did controls. The presence or deposition of mucus on the surface of skin indicated likely molecular interaction between constituents of mucus and LAS.

  13. Pink-Beam, Highly-Accurate Compact Water Cooled Slits

    SciTech Connect

    Lyndaker, Aaron; Deyhim, Alex; Jayne, Richard; Waterman, Dave; Caletka, Dave; Steadman, Paul; Dhesi, Sarnjeet

    2007-01-19

    Advanced Design Consulting, Inc. (ADC) has designed accurate compact slits for applications where high precision is required. The system consists of vertical and horizontal slit mechanisms, a vacuum vessel which houses them, water cooling lines with vacuum guards connected to the individual blades, stepper motors with linear encoders, limit (home position) switches and electrical connections including internal wiring for a drain current measurement system. The total slit size is adjustable from 0 to 15 mm both vertically and horizontally. Each of the four blades are individually controlled and motorized. In this paper, a summary of the design and Finite Element Analysis of the system are presented.

  14. A Biochemical Double Slit

    NASA Astrophysics Data System (ADS)

    Kominis, Iannis

    2011-03-01

    Radical-ion-pair reactions, fundamental in photosynthesis and at the basis of the avian magnetic compass mechanism, have been recently shown to offer a rich playground for applying methods and concepts from quantum measurement/quantum information science. We will demonstrate that radical-ion-pair reactions are almost the exact analog of the optical double slit experiment, i.e. Nature has already engineered biochemical reactions performing the act of quantum interference. We will further elaborate on the non-trivial quantum effects pertaining in these reactions and the recent debate on their fundamental theoretical description that these effects have sparked.

  15. Age and indications to SLIT.

    PubMed

    Terracciano, L; Calcinai, E; Avitabile, S; Galli, E

    2009-01-01

    Clinical efficacy of sublingual immunotherapy (SLIT) has been investigated during the last 20 years and results of several meta-analyses are available, showing clinical efficacy of SLIT in children both in allergic asthma and in rhinitis, but strict recommendations are not possible under current evidence. Minimum age for starting SLIT is not clearly defined but several position paper and guidelines indicate a lower limit of 5 years of age. Guidelines on allergic rhinitis suggests SLIT in patients not well controlled with drugs or those who refuse to use drugs. Additional effects are prevention of new sensitizations (evidence IIa) and prevention of asthma in patients with allergic rhinitis (evidence I b). Studies on efficacy of SLIT in asthmatic children are discordant, but the different relevance of allergic and non allergic triggers of symptoms could explain the discordant results obtained in studies on SLIT and asthma, particularly when pooling short and long term studies. Data on efficacy and safety of SLIT are accruing for atopic dermatitis, food allergy and latex allergy, but at the current state of knowledge, SLIT remains an approach reserved to research, and no recommendations can be established. Some studies demonstrate that SLIT is safe in children below 5 years of age, with a lower limit of 3 years.

  16. Long-term efficacy of linear-scanning 808 nm diode laser for hair removal compared to a scanned alexandrite laser.

    PubMed

    Grunewald, Sonja; Bodendorf, Marc Oliver; Zygouris, Alexander; Simon, Jan Christoph; Paasch, Uwe

    2014-01-01

    Alexandrite and diode lasers are commonly used for hair removal. To date, the available spot sizes and repetition rates are defining factors in terms of penetration depth, treatment speed, and efficacy. Still, larger treatment areas and faster systems are desirable. To compare the efficacy, tolerability, and subject satisfaction of a continuously linear-scanning 808 nm diode laser with an alexandrite 755 nm laser for axillary hair removal. A total of 31 adults with skin types I-IV received 6 treatments at 4-week intervals with a 755 nm alexandrite laser (right axilla) and a continuously linear-scanning 808 nm diode laser (left axilla). Axillary hair density was assessed using a computerized hair detection system. There was a significant reduction in axillary hair after the 6th treatment (P < 0.05) on both sides (left, 808 nm: hair clearance of 72.16%; right, 755 nm: hair clearance of 71.30%). The difference in reduction between the two lasers was not significant, but both were persistant at 18 months follow-up (left: hair clearance of 73.71%; right: hair clearance of 71.90%). Erythema and perifollicular edema were more common after alexandrite laser treatment, but all side effects were transient. While 62.50% of patients reported more pain in response to treatment with the new diode laser, all patients rated treatment with either laser tolerable. Treatment with either the alexandrite or the linear-scanning diode laser results in significant, comparable, persistent (at least 18 months) axillary hair reduction among individuals with skin types I-IV. © 2013 Wiley Periodicals, Inc.

  17. Biphoton double-slit experiment

    SciTech Connect

    Brida, G.; Cagliero, E.; Falzetta, G.; Genovese, M.; Gramegna, M.; Predazzi, E.

    2003-09-01

    In this paper we present a double-slit experiment where two indistinguishable photons produced by type-I parametric down-conversion are each sent to a well-defined slit. Data about the diffraction and interference patterns for coincidences are presented and discussed. An analysis of these data allows a test of standard quantum mechanics against the de Broglie-Bohm theory.

  18. Image formation by linear and nonlinear digital scanned light-sheet fluorescence microscopy with Gaussian and Bessel beam profiles

    PubMed Central

    Olarte, Omar E.; Licea-Rodriguez, Jacob; Palero, Jonathan A.; Gualda, Emilio J.; Artigas, David; Mayer, Jürgen; Swoger, Jim; Sharpe, James; Rocha-Mendoza, Israel; Rangel-Rojo, Raul; Loza-Alvarez, Pablo

    2012-01-01

    We present the implementation of a combined digital scanned light-sheet microscope (DSLM) able to work in the linear and nonlinear regimes under either Gaussian or Bessel beam excitation schemes. A complete characterization of the setup is performed and a comparison of the performance of each DSLM imaging modality is presented using in vivo Caenorhabditis elegans samples. We found that the use of Bessel beam nonlinear excitation results in better image contrast over a wider field of view. PMID:22808423

  19. Polarization singularities in Young's two-slit experiment

    NASA Astrophysics Data System (ADS)

    Lian, Xiaoxu; Lü, Baida

    2011-10-01

    Young's interference experiment is regarded as a two-slit diffraction phenomenon, the polarization singularities in Young's two-slit configuration illuminated with two linearly, orthogonally polarized Gaussian vortex beams are studied. It is shown that generally, there exist L-lines (linearly polarization) and polarization singularities including C-points (circular polarization), S23 and S31 singularities even though the parameters of two beams are the same. The pair creation-annihilation and motion of polarization singularities take place upon propagation, or by varying a control parameter, such as the amplitude ratio of two beams or obscure ratio of slits etc. For a special case of the illumination with two linearly, orthogonally polarized Gaussian vortex-free beams, polarization singularities, in particular, C-points may occur if a parameter of two beams is not equal.

  20. Optical double-slit particle measuring system

    DOEpatents

    Tichenor, D.A.; Wang, J.C.F.; Hencken, K.R.

    1982-03-25

    A method for in situ measurement of particle size is described. The size information is obtained by scanning an image of the particle across a double-slit mask and observing the transmitted light. This method is useful when the particle size of primary interest is 3..mu..m and larger. The technique is well suited to applications in which the particles are non-spherical and have unknown refractive index. It is particularly well suited to high temperature environments in which the particle incandescence provides the light source.

  1. Optical double-slit particle measuring system

    DOEpatents

    Hencken, Kenneth R.; Tichenor, Daniel A.; Wang, James C. F.

    1984-01-01

    A method for in situ measurement of particle size is described. The size information is obtained by scanning an image of the particle across a double-slit mask and observing the transmitted light. This method is useful when the particle size of primary interest is 3 .mu.m and larger. The technique is well suited to applications in which the particles are non-spherical and have unknown refractive index. It is particularly well suited to high temperature environments in which the particle incandescence provides the light source.

  2. A pressure scanning Fabry-Perot magnetometer.

    NASA Technical Reports Server (NTRS)

    Fay, T. D.; Wyller, A. A.

    1971-01-01

    Description of an oscillating magnetic analyzer (KDP crystal plus Glan-Thompson prism) coupled to an echelle-interferometer spectrograph, and of single-slit magnetometer which by pressure variations can be made to scan the entire profiles of the circularly and linearly polarized Zeeman components. Freon gas is used as the scanner gas with wavelength displacements of 0.02 A per 0.1 in. Hg pressure change at the NaD lines. The available scan range is 15 A in the visual spectral region.

  3. Linear terrestrial laser scanning using array avalanche photodiodes as detectors for rapid three-dimensional imaging.

    PubMed

    Cai, Yinqiao; Tong, Xiaohua; Tong, Peng; Bu, Hongyi; Shu, Rong

    2010-12-01

    As an active remote sensor technology, the terrestrial laser scanner is widely used for direct generation of a three-dimensional (3D) image of an object in the fields of geodesy, surveying, and photogrammetry. In this article, a new laser scanner using array avalanche photodiodes, as designed by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, is introduced for rapid collection of 3D data. The system structure of the new laser scanner is first presented, and a mathematical model is further derived to transform the original data to the 3D coordinates of the object in a user-defined coordinate system. The performance of the new laser scanner is tested through a comprehensive experiment. The result shows that the new laser scanner can scan a scene with a field view of 30° × 30° in 0.2 s and that, with respect to the point clouds obtained on the wall and ground floor surfaces, the root mean square errors for fitting the two planes are 0.21 and 0.01 cm, respectively. The primary advantages of the developed laser scanner include: (i) with a line scanning mode, the new scanner achieves simultaneously the 3D coordinates of 24 points per single laser pulse, which enables it to scan faster than traditional scanners with a point scanning mode and (ii) the new scanner makes use of two galvanometric mirrors to deflect the laser beam in both the horizontal and the vertical directions. This capability makes the instrument smaller and lighter, which is more acceptable for users.

  4. Process for manufacturing slit collimators

    NASA Technical Reports Server (NTRS)

    Romanenko, V. P.; Yemelyanov, A. A.; Churbakov, K. I.

    1974-01-01

    Peculiarities are described of the manufacturing process and the control of elements of slit collimators, the structural design of the required equipment and the process or assembling the collimators.

  5. Micromachined Slits for Imaging Spectrometers

    NASA Technical Reports Server (NTRS)

    Wilson, Daniel; Kenny, James; White, Victor

    2008-01-01

    Slits for imaging spectrometers can now be fabricated to a precision much greater than previously attainable. What makes this possible is a micromachining process that involves the use of microlithographic techniques.

  6. Image reconstruction based on total-variation minimization and alternating direction method in linear scan computed tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Han-Ming; Wang, Lin-Yuan; Yan, Bin; Li, Lei; Xi, Xiao-Qi; Lu, Li-Zhong

    2013-07-01

    Linear scan computed tomography (LCT) is of great benefit to online industrial scanning and security inspection due to its characteristics of straight-line source trajectory and high scanning speed. However, in practical applications of LCT, there are challenges to image reconstruction due to limited-angle and insufficient data. In this paper, a new reconstruction algorithm based on total-variation (TV) minimization is developed to reconstruct images from limited-angle and insufficient data in LCT. The main idea of our approach is to reformulate a TV problem as a linear equality constrained problem where the objective function is separable, and then minimize its augmented Lagrangian function by using alternating direction method (ADM) to solve subproblems. The proposed method is robust and efficient in the task of reconstruction by showing the convergence of ADM. The numerical simulations and real data reconstructions show that the proposed reconstruction method brings reasonable performance and outperforms some previous ones when applied to an LCT imaging problem.

  7. Bandwidth control of forbidden transmission gaps in compound structures with subwavelength slits.

    PubMed

    Skigin, Diana C; Loui, Hung; Popovic, Zoya; Kuester, Edward F

    2007-07-01

    Phase resonances in transmission compound structures with subwavelength slits produce sharp dips in the transmission response. For all equal slits, the wavelengths of these sharp transmission minima can be varied by changing the width or the length of all the slits. In this paper we show that the width of the dip, i.e., the frequency range of minimum transmittance, can be controlled by making at least one slit different from the rest within a compound unit cell. In particular, we investigate the effect that a change in the dielectric filling, or in the length of a single slit, produces in the transmission response. We also analyze the scan angle behavior of these structures by means of band diagrams and compare them with previous results for all-equal slit structures.

  8. SEM analysis of ionizing radiation effects in linear integrated circuits. [Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

    Stanley, A. G.; Gauthier, M. K.

    1977-01-01

    A successful diagnostic technique was developed using a scanning electron microscope (SEM) as a precision tool to determine ionization effects in integrated circuits. Previous SEM methods radiated the entire semiconductor chip or major areas. The large area exposure methods do not reveal the exact components which are sensitive to radiation. To locate these sensitive components a new method was developed, which consisted in successively irradiating selected components on the device chip with equal doses of electrons /10 to the 6th rad (Si)/, while the whole device was subjected to representative bias conditions. A suitable device parameter was measured in situ after each successive irradiation with the beam off.

  9. Flatness characteristics for diagonal scans from Varian and Siemens linear accelerators.

    PubMed

    Dawson, J; Kahler, D; Gu, J; McDonald, B; Abrath, F; Kopecky, W

    1996-09-01

    The advent of 3D treatment planning systems whose algorithms utilize diagonal scan data to perform dose calculations has made the collection of diagonal profile data essential. Manufacturers' specifications (MS) on beam flatness and symmetry apply to both the radial and transverse axes of all square field sizes from 10 X 10 cm2 to the largest field available. Beam profile measurements were obtained for both diagonal axes over a range of field sizes and depths for two units, a Varian 2100C and a Siemens KD. In this note the International Electrotechnical Commission (IEC) flatness definition was used to characterize the diagonal flatness of each beam.

  10. [A micro-silicon multi-slit spectrophotometer based on MEMS technology].

    PubMed

    Hao, Peng; Wu, Yi-Hui; Zhang, Ping; Liu, Yong-Shun; Zhang, Ke; Li, Hai-Wen

    2009-06-01

    A new mini-spectrophotometer was developed by adopting micro-silicon slit and pixel segmentation technology, and this spectrophotometer used photoelectron diode array as the detector by the back-dividing-light way. At first, the effect of the spectral bandwidth on the tested absorbance linear correlation was analyzed. A theory for the design of spectrophotometer's slit was brought forward after discussing the relationships between spectrophotometer spectrum band width and pre-and post-slits width. Then, the integrative micro-silicon-slit, which features small volume, high precision, and thin thickness, was manufactured based on the MEMS technology. Finally, a test was carried on linear absorbance solution by this spectrophotometer. The final result showed that the correlation coefficients were larger than 0.999, which means that the new mini-spectrophotometer with micro-silicon slit pixel segmentation has an obvious linear correlation.

  11. [The linear hyperspectral camera rotating scan imaging geometric correction based on the precise spectral sampling].

    PubMed

    Wang, Shu-min; Zhang, Ai-wu; Hu, Shao-xing; Wang, Jing-meng; Meng, Xian-gang; Duan, Yi-hao; Sun, Wei-dong

    2015-02-01

    As the rotation speed of ground based hyperspectral imaging system is too fast in the image collection process, which exceeds the speed limitation, there is data missed in the rectified image, it shows as the_black lines. At the same time, there is serious distortion in the collected raw images, which effects the feature information classification and identification. To solve these problems, in this paper, we introduce the each component of the ground based hyperspectral imaging system at first, and give the general process of data collection. The rotation speed is controlled in data collection process, according to the image cover area of each frame and the image collection speed of the ground based hyperspectral imaging system, And then the spatial orientation model is deduced in detail combining with the star scanning angle, stop scanning angle and the minimum distance between the sensor and the scanned object etc. The oriented image is divided into grids and resampled with new spectral. The general flow of distortion image corrected is presented in this paper. Since the image spatial resolution is different between the adjacent frames, and in order to keep the highest image resolution of corrected image, the minimum ground sampling distance is employed as the grid unit to divide the geo-referenced image. Taking the spectral distortion into account caused by direct sampling method when the new uniform grids and the old uneven grids are superimposed to take the pixel value, the precise spectral sampling method based on the position distribution is proposed. The distortion image collected in Lao Si Cheng ruin which is in the Zhang Jiajie town Hunan province is corrected through the algorithm proposed on above. The features keep the original geometric characteristics. It verifies the validity of the algorithm. And we extract the spectral of different features to compute the correlation coefficient. The results show that the improved spectral sampling method is

  12. Expression of Slit and Robo genes in the developing mouse heart.

    PubMed

    Medioni, Caroline; Bertrand, Nicolas; Mesbah, Karim; Hudry, Bruno; Dupays, Laurent; Wolstein, Orit; Washkowitz, Andrew J; Papaioannou, Virginia E; Mohun, Timothy J; Harvey, Richard P; Zaffran, Stéphane

    2010-12-01

    Development of the mammalian heart is mediated by complex interactions between myocardial, endocardial, and neural crest-derived cells. Studies in Drosophila have shown that the Slit-Robo signaling pathway controls cardiac cell shape changes and lumen formation of the heart tube. Here, we demonstrate by in situ hybridization that multiple Slit ligands and Robo receptors are expressed in the developing mouse heart. Slit3 is the predominant ligand transcribed in the early mouse heart and is expressed in the ventral wall of the linear heart tube and subsequently in chamber but not in atrioventricular canal myocardium. Furthermore, we identify that the homeobox gene Nkx2-5 is required for early ventral restriction of Slit3 and that the T-box transcription factor Tbx2 mediates repression of Slit3 in nonchamber myocardium. Our results suggest that patterned Slit-Robo signaling may contribute to the control of oriented cell growth during chamber morphogenesis of the mammalian heart.

  13. Compact very low temperature scanning tunneling microscope with mechanically driven horizontal linear positioning stage.

    PubMed

    Suderow, H; Guillamon, I; Vieira, S

    2011-03-01

    We describe a scanning tunneling microscope for operation in a dilution refrigerator with a sample stage which can be moved macroscopically in a range up to a cm and with an accuracy down to the tens of nm. The position of the tip over the sample as set at room temperature does not change more than a few micrometers when cooling down. This feature is particularly interesting for work on micrometer sized samples. Nanostructures can be also localized and studied, provided they are repeated over micrometer sized areas. The same stage can be used to approach a hard single crystalline sample to a knife and cleave it, or break it, in situ. In situ positioning is demonstrated with measurements at 0.1 K in nanofabricated samples. Atomic resolution down to 0.1 K and in magnetic fields of 8 T is demonstrated in NbSe(2). No heat dissipation nor an increase in mechanical noise has been observed at 0.1 K when operating the slider.

  14. X-ray diffraction from rectangular slits.

    PubMed

    Le Bolloc'h, D; Livet, F; Bley, F; Schulli, T; Veron, M; Metzger, T H

    2002-07-01

    It is shown that for micrometre-sized beams the X-ray diffraction from slits is a source of strong parasitic background, even for slits of high quality. In order to illustrate this effect, the coherent diffraction from rectangular slits has been studied in detail. A large number of interference fringes with strong visibility have been observed using a single set of slits made of polished cylinders. For very small apertures, asymmetrical slits generate asymmetrical patterns. This pattern is calculated from the theory of electromagnetic field propagation and compared with experiment in the far-field regime. The use of guard slits to remove Fraunhofer diffraction from the beam-defining slits is treated theoretically. Numerical simulations yield the optimum aperture of the guard slits with respect to the distance to the primary slits. Diffraction theory is shown to be essential to understand how to reduce the background-to-signal ratio in high-resolution experiments.

  15. Neuropathological findings in a child with slit ventricle syndrome.

    PubMed

    Del Bigio, Marc R

    2002-09-01

    The histopathological changes in shunted hydrocephalic children with slit ventricle syndrome have never been described. Periventricular gliosis is presumed to be an important feature. A girl who was shunted in infancy following meningitis developed headaches at 10 years of age and suffered a respiratory arrest, from which she was resuscitated. CT scan of the head showed very small ventricles. A diagnosis of slit ventricle syndrome was made. She died 33 h later. Autopsy revealed a large head and brain, small ventricles with glial adhesions, obstruction of the cerebral aqueduct, complete obstruction of the shunt catheter and reactive astroglia in the periventricular white matter. The latter change was no more severe than in hydrocephalic children with enlarged ventricles who have died following shunt failure. Periventricular astrogliosis may not necessarily be the major determinant of the slit ventricle syndrome.

  16. Application of Fermi scattering theory to a magnetically scanned electron linear accelerator.

    PubMed

    Sandison, G A; Huda, W

    1988-01-01

    This paper uses a solution to the Fermi electron transport equation for an isotropic point source to characterize the magnetically scanned broad electron beams from the Sagittaire Therac 40 accelerator in the air space above patients. Thick lead collimation is shown to be adequately modeled by an infinitely thin absorbing plate when used to predict penumbra shape. A relationship between broad beam penumbra width and the value of the root-mean-square spatial Gaussian spread sigma (z) of an elementary pencil beam is derived. This relationship is applicable for any rectangular field size. Measurement of the variation in broad beam penumbra width with source-surface distance (SSD) for a 7-MeV beam locates the isotropic source to be coincident with the exit window of the accelerator and indicates that the scattering effect of the monitor chamber may be considered negligibly small. Using this source location accurate predictions of beam profile shape for any clinically used beam energy, SSD, or field size are made in the presence of lead trimmer collimation. Field penumbra beyond the photon collimation system is formed in each lateral direction by two lead blocks whose faces are aligned along a diverging ray emanating from the source. The photon collimator closest to the source restricts the field size causing a variation of both fluence and the mean square angle spread of the electrons across the plane at the level of the lower collimator. This variation is accounted for by introducing an empirical perturbation factor into the mathematical formalism. An interesting feature of this perturbation factor is that it is field size dependent and its effect on penumbra width may be scaled for both beam energy and SSD to accurately predict beam profile shape.

  17. Application of Fermi scattering theory to a magnetically scanned electron linear accelerator

    SciTech Connect

    Sandison, G.A.; Huda, W.

    1988-07-01

    This paper uses a solution to the Fermi electron transport equation for an isotropic point source to characterize the magnetically scanned broad electron beams from the Sagittaire Therac 40 accelerator in the air space above patients. Thick lead collimation is shown to be adequately modeled by an infinitely thin absorbing plate when used to predict penumbra shape. A relationship between broad beam penumbra width and the value of the root-mean-square spatial Gaussian spread sigma (z) of an elementary pencil beam is derived. This relationship is applicable for any rectangular field size. Measurement of the variation in broad beam penumbra width with source-surface distance (SSD) for a 7-MeV beam locates the isotropic source to be coincident with the exit window of the accelerator and indicates that the scattering effect of the monitor chamber may be considered negligibly small. Using this source location accurate predictions of beam profile shape for any clinically used beam energy, SSD, or field size are made in the presence of lead trimmer collimation. Field penumbra beyond the photon collimation system is formed in each lateral direction by two lead blocks whose faces are aligned along a diverging ray emanating from the source. The photon collimator closest to the source restricts the field size causing a variation of both fluence and the mean square angle spread of the electrons across the plane at the level of the lower collimator. This variation is accounted for by introducing an empirical perturbation factor into the mathematical formalism. An interesting feature of this perturbation factor is that it is field size dependent and its effect on penumbra width may be scaled for both beam energy and SSD to accurately predict beam profile shape.

  18. Structural insight into Slit-Robo signalling.

    PubMed

    Hohenester, Erhard

    2008-04-01

    Drosophila Slit and its vertebrate orthologues Slit1-Slit3 are secreted glycoproteins that play important roles in the development of the nervous system and other organs. Human Slits are also involved in a number of pathological situations, such as cancer and inflammation. Slits exert their effects by activating receptors of the Robo (Roundabout) family, which resemble cell adhesion molecules in their ectodomains and have large, mainly unstructured cytosolic domains. HS (heparan sulfate) is required for Slit-Robo signalling. The hallmark of Slit proteins is a tandem of four LRR (leucine-rich repeat) domains, which mediate binding to the IG (immunoglobulin-like) domains of Robos. A major question is how Slit binding is translated into the recruitment of effector molecules to the cytosolic domain of Robo. Detailed structure-function studies have shown that the second LRR domain of Slit (D2) binds to the first two IG domains of Robo, and that HS serves to stabilize the Slit-Robo interaction and is required for biological activity of Slit D2. Very recently, the crystal structure of a minimal Slit-Robo complex revealed that the IG1 domain of Robo is bound by the concave face of Slit D2, confirming earlier mutagenesis data. To define the mechanism of Robo transmembrane signalling, these structural insights will have to be complemented by new cell biology and microscopy approaches.

  19. Catalytic kinetic determination of ultratrace amounts of nitrite with detection by linear scan voltammetry at a DME.

    PubMed

    Zhi-Liang, J; Hai-Cuo, Q; Da-Qiang, W

    1992-10-01

    Nitrite has a very strong catalytic effect on the bromate oxidation of Methyl Orange in dilute sulphuric acid medium. The oxidation product of methyl orange exhibits a well derivative voltammetric wave at -0.41 V vs. SCE in sodium hydroxide medium. The linear scan voltammetric behaviour for the product at a DME has been studied, and it was selected as indicator component for the indicator reaction. Based on these studies, a novel and highly sensitive and selective catalytic reaction-voltammetric method for nitrite is proposed. A detection limit of 2 x 10(-9)M and calibration graph from 4 x 10(-7) to 4 x 10(-7)M nitrite are obtained. Nitrite in water samples was determined by this method, with satisfactory results.

  20. Radiation parameters of 6 to 20 MeV scanning electron beams from the Saturne linear accelerator.

    PubMed

    Pfalzner, P M; Clarke, H C

    1982-01-01

    Depth doses of the scanning electron beams from the Saturne Therac-20 linear accelerator at nominal energies of 6,9,13,17, and 20 MeV were measured in polystyrene using a thin window parallel plate ionization chamber. Central axis depth dose curves are derived and are analyzed according to the method of Brahme and Svensson. For each of the five electron energies, values are obtained for the most probable energy at the absorber surface Ep,0, the practical range Rp, the 50% range R50, the therapeutic range R85, the electron dose gradients, total collision energy losses, and other radiation parameters, and these are compared to corresponding values for electron beams from a 22 MeV medical microtron and a 20 MeV betatron.

  1. "Quantum Interference with Slits" Revisited

    ERIC Educational Resources Information Center

    Rothman, Tony; Boughn, Stephen

    2011-01-01

    Marcella has presented a straightforward technique employing the Dirac formalism to calculate single- and double-slit interference patterns. He claims that no reference is made to classical optics or scattering theory and that his method therefore provides a purely quantum mechanical description of these experiments. He also presents his…

  2. "Quantum Interference with Slits" Revisited

    ERIC Educational Resources Information Center

    Rothman, Tony; Boughn, Stephen

    2011-01-01

    Marcella has presented a straightforward technique employing the Dirac formalism to calculate single- and double-slit interference patterns. He claims that no reference is made to classical optics or scattering theory and that his method therefore provides a purely quantum mechanical description of these experiments. He also presents his…

  3. Slit Function Measurement of An Imaging Spectrograph Using Fourier Transform Techniques

    NASA Technical Reports Server (NTRS)

    Park, Hongwoo; Swimyard, Bruce; Jakobsen, Peter; Moseley, Harvey; Greenhouse, Matthew

    2004-01-01

    Knowledge of a spectrograph slit function is necessary to interpret the unresolved lines in an observed spectrum. A theoretical slit function can be calculated from the sizes of the entrance slit, the detector aperture when it functions as an exit slit, the dispersion characteristic of the disperser, and the point spread function of the spectrograph. A measured slit function is preferred to the theoretical one for the correct interpretation of the spectral data. In a scanning spectrometer with a single exit slit, the slit function is easily measured. In a fixed grating/or disperser spectrograph, illuminating the entrance slit with a near monochromatic light from a pre-monochrmator or a tunable laser and varying the wavelength of the incident light can measure the slit function. Even though the latter technique had been used successfully for the slit function measurements, it had been very laborious and it would be prohibitive to an imaging spectrograph or a multi-object spectrograph that has a large field of view. We explore an alternative technique that is manageable for the measurements. In the proposed technique, the imaging spectrograph is used as a detector of a Fourier transform spectrometer. This method can be applied not only to an IR spectrograph but also has a potential to a visible/UV spectrograph including a wedge filter spectrograph. This technique will require a blackbody source of known temperature and a bolometer to characterize the interferometer part of the Fourier Transform spectrometer. This pa?er will describe the alternative slit function measurement technique using a Fourier transform spectrometer.

  4. Controlled double-slit electron diffraction

    NASA Astrophysics Data System (ADS)

    Bach, Roger; Pope, Damian; Liou, Sy-Hwang; Batelaan, Herman

    2013-03-01

    Double-slit diffraction is a corner stone of quantum mechanics. It illustrates key features of quantum mechanics: interference and the particle-wave duality of matter. In 1965, Richard Feynman presented a thought experiment to show these features. Here we demonstrate the full realization of his famous thought experiment. By placing a movable mask in front of a double-slit to control the transmission through the individual slits, probability distributions for single- and double-slit arrangements were observed. Also, by recording single electron detection events diffracting through a double-slit, a diffraction pattern was built up from individual events.

  5. [Method of measuring modulation transfer function in computed tomography using slit method with air gap phantom].

    PubMed

    Uto, Tomoyuki; Yukimura, Yoshihiro; Kouzuki, Kiyoaki; Isotani, Keisuke

    2012-01-01

    There are several methods for measuring modulation transfer function (MTF) in computed tomography (CT) images. The aluminum slit method, scanning a phantom consisting of a thin aluminum foil sandwiched by flat plastic slabs, is a standard method for measuring field of view (FOV) in clinical CT scan. But this method requires extreme caution when handling metal foil of high precision. Therefore, we devised a more simple method named air gap slit (AS) method. This new technique is based on the aluminum slit method but use air gap instead of metal foil between phantoms. The MTF was calculated from a reversed profile curve of air slit which indicated minimum CT number. The aim of this study was to investigate a possibility of AS method evaluating MTF. We investigated fluctuation of MTF and FOV in clinical CT scan compared with the aluminum slit method. The result showed that the fluctuation of MTF was caused by statistics noise and is more affected by a bone kernel than standard kernel when reconstructing. Also, the MTF value in AS method was slightly higher than in aluminum slit method and did not correspond with. AS method is a useful method for measurement of MTF in clinical CT scan. When we use this method, we have to take into consideration the noise influence of data.

  6. Subwavelength slit acoustic metamaterial barrier

    NASA Astrophysics Data System (ADS)

    Rubio, Constanza; Candelas, Pilar; Belmar, Francisco; Gomez-Lozano, Vicente; Uris, Antonio

    2015-10-01

    Reduction of noise in the transmission path is a very important environmental problem. The standard method to reduce this noise level is the use of acoustic barriers. In this paper, an acoustic metamaterial based on sound transmission through subwavelength slits, is tailored to be used as an acoustic barrier. This system consists of two rows of periodic repetition of vertical rigid pickets separated by a slit of subwavelength width, embedded in air. Here, both the experimental and the numerical analyses are presented. These analyses have facilitated the identification of the parameters that affect the insertion loss performance. The results demonstrated that the proposed barrier can be tuned to mitigate a band noise in a mechanical plant for buildings where openings for air flow are required as well as industrial noise, without excessive barrier thickness.

  7. Spatial light interference tomography (SLIT)

    PubMed Central

    Wang, Zhuo; Marks, Daniel L.; Carney, Paul Scott; Millet, Larry J.; Gillette, Martha U.; Mihi, Agustin; Braun, Paul V.; Shen, Zhen; Prasanth, Supriya G.; Popescu, Gabriel

    2011-01-01

    We present spatial light interference tomography (SLIT), a label-free method for 3D imaging of transparent structures such as live cells. SLIT uses the principle of interferometric imaging with broadband fields and combines the optical gating due to the micron-scale coherence length with that of the high numerical aperture objective lens. Measuring the phase shift map associated with the object as it is translated through focus provides full information about the 3D distribution associated with the refractive index. Using a reconstruction algorithm based on the Born approximation, we show that the sample structure may be recovered via a 3D, complex field deconvolution. We illustrate the method with reconstructed tomographic refractive index distributions of microspheres, photonic crystals, and unstained living cells. PMID:21996999

  8. Automatic multidiagnosis system for slit lamp

    NASA Astrophysics Data System (ADS)

    Ventura, Liliane; Chiaradia, Caio; Vieira Messias, Andre M.; Faria de Sousa, Sidney J.; Isaac, Flavio; Caetano, Cesar A. C.; Rosa Filho, Andre B.

    2001-06-01

    We have developed a system for several automatic diagnose in Slit Lamp in order to provide 04 additional measurements to the biomicroscope: (1) counting of the endothelial cells of donated corneas; (2) automatic keratometry; (3) corneal ulcer evaluation; (4) measurement of linear distances and areas of the ocular image. The system consists in a Slit Lamp, a beam-splitter, some optical components, a CCD detector, a frame grabber and a PC. The optical components attached to the beam-splitter are the same for all the functions, except for 1. For function 1, we have developed an optical system that magnifies the image 290X and a software that counts the cells interactively and automatically. Results are in good agreement with commercial specular microscopes (correlation coefficient is 0,98081). The automatic keratometry function is able to measure cylinders over 30 di and also irregular astigmatisms. The system consists of projecting a light ring at the patient's cornea and the further analysis of the deformation of the ring provides the radius of curvature as well as the axis of the astigmatism. The nominal precision is 0,005 mm for the curvature radius and 2 degree(s) for the axis component. The results are in good agreement with commercial systems (correlation coefficient of 0,99347). For function 3, the ulcer is isolated by the usual clinical ways and the image of the green area is automatically detected by the developed software in order to evaluate the evolution of the disease. Function 4 simply allows the clinician do any linear or area measurement of the ocular image. The system is a low cost multi evaluation equipment and it is being used in a public hospital in Brazil.

  9. Slit lamp photography: The basics.

    PubMed

    Painter, Rosalyn

    2015-06-01

    This introductory paper is designed to explain the basics of slit lamp photography with the use of illustrations and sample images. The two primary methods of illumination are described with reference to positioning and magnification, as well as the use of background illumination. Filters and dye usage are described along with a brief explanation of associated imaging techniques. Further explanation of techniques will be looked at in subsequent articles, this paper aims to give an over view rather than an in-depth discussion of techniques.

  10. Exit slit mirrors for the ebert spectrometer.

    PubMed

    Fastie, W G

    1972-09-01

    The use of a very long straight entrance slit in an Ebert grating spectrometer with two plane mirrors at the shorter exit slit to increase the energy density is described. This system has been employed in a far uv rocket spectrometer to provide higher sensitivity than has been achieved previously. The imaging properties and required slit and mirror adjustments are presented. Experimental results are included.

  11. Mapping the double-slit diffraction pattern

    NASA Astrophysics Data System (ADS)

    Selvaggi, Richard; Rogers, Charles; Richardson, Clay

    2010-10-01

    A red laser, movable double-slit, movable micrometer mounted single-slit light block, and CCD were utilized to map out the single and double-slit diffraction patterns between 0 and 30 millimeters. The three dimensional mapping results demonstrate that the double-slit troughs similarly redirect the electromagnetic energy and light particles. The measured alternating path of the electromagnetic energy and light particles in the double-slit diffraction pattern is different than the theoretic path of light waves defined by destructive interference and indicates that theoretical light waves do not always have electromagnetic energy. George Monk's 1937 and Richard Feynman's 1964 finding of conservation of electromagnetic energy in the double-slit light experiment present the following questions: 1) What are the mass-less and energy-less destructive interference light waves found in the double-slit troughs? 2) What force is applied to and what energy is consumed by the work of redistributing the electromagnetic energy and light particles in the double-slit diffraction pattern? 3) Is this unknown force and unknown energy the result of dark matter found in the double-slit troughs?

  12. Slit device for FOCCoS-PFS-Subaru

    NASA Astrophysics Data System (ADS)

    de Oliveira, Antonio Cesar; Gunn, James E.; de Oliveira, Ligia Souza; Vital de Arruda, Marcio; Souza Marrara, Lucas; dos Santos, Leandro Henrique; Ferreira, Décio; dos Santos, Jesulino Bispo; Rosa, Josimar Aparecido; Ribeiro, Flavio Felipe; Vilaça, Rodrigo de Paiva; Verducci, Orlando; Sodré, Laerte; Oliveira, Claudia Mendes

    2014-07-01

    The Fiber Optical Cable and Connector System, "FOCCoS", subsystem of the Prime Focus Spectrograph, "PFS", for Subaru telescope, is responsible to feed four spectrographs with a set of optical fibers cables. The light injection for each spectrograph is assured by a convex curved slit with a linear array of 616 optical fibers. In this paper we present a design of a slit that ensures the right direction of the fibers by using masks of micro holes. This kind of mask is made by a technique called electroforming, which is able to produce a nickel plate with holes in a linear sequence. The precision error is around 1-μm in the diameter and 1-μm in the positions of the holes. This nickel plate may be produced with a thickness between 50 and 200 microns, so it may be very flexible. This flexibility allows the mask to be bent into the shape necessary for a curved slit. The concept requires two masks, which we call Front Mask, and Rear Mask, separated by a gap that defines the thickness of the slit. The pitch and the diameter of the holes define the linear geometry of the slit; the curvature of each mask defines the angular geometry of the slit. Obviously, this assembly must be mounted inside a structure rigid and strong enough to be supported inside the spectrograph. This structure must have a CTE optimized to avoid displacement of the fibers or increased FRD of the fibers when the device is submitted to temperatures around 3 degrees Celsius, the temperature of operation of the spectrograph. We have produced two models. Both are mounted inside a very compact Invar case, and both have their front surfaces covered by a dark composite, to reduce stray light. Furthermore, we have conducted experiments with two different internal structures to minimize effects caused by temperature gradients. This concept has several advantages relative to a design based on Vgrooves, which is the classical option. It is much easier and quicker to assemble, much cheaper, more accurate, easier to

  13. [Phimosis: dorsal slit or circumcision?].

    PubMed

    Corona, C; Cañizo, A; Cerda, J; Fanjul, M; Carrera, N; Tardáguila, A; Zornoza, M; Parente, A; Angulo, J M; De Tomás, E; Molina, E; Peláez, D; García Casillas, M A; Rivas, S; Romero, R; Marín, M C

    2011-01-01

    Phimosis is perhaps one of the most frequent consultation on pediatric surgery clinics throught the world. The aim of this study is to compare the two procedures more frequently performed in our hospital: dorsal slit and circumcision. PATIENTS Y METHODS: Retrospective study of 1698 patients who were admitted for elective surgical treatment of phimosis between 2003 and 2009. We analyzed age, surgical and anesthethic times, surgical technique and complications. We also did transversal descriptive study through telephonic survey on parents and patients older than 16 years old. There was 76.6% of dorsal slit (n = 1300) and 23.4% (n= 398) of circumcisions. Mean age was 7.15 years y mean time of follow up was 42.3 months. Surgical time was significantly higher in circumcision (p < 0.0001). There were 3% (n = 51) of reoperations, no differences between groups. We didn't find differences in postoperative stenosis, but bleeding was more frequent in circumcision group (1.7%; p = 0.03). There were no differences on parental appreciation of postoperative pain, or functional and esthetic satisfaction between groups. We didn't find differences on subjective satisfaction between groups. Even if there are differences n postoperative bleeding, global incidence is very low. In our experience both techniques are valid and safe, so surgeon and parents must jointly make the decision.

  14. Time-resolved double-slit interference pattern measurement with entangled photons.

    PubMed

    Kolenderski, Piotr; Scarcella, Carmelo; Johnsen, Kelsey D; Hamel, Deny R; Holloway, Catherine; Shalm, Lynden K; Tisa, Simone; Tosi, Alberto; Resch, Kevin J; Jennewein, Thomas

    2014-04-28

    The double-slit experiment strikingly demonstrates the wave-particle duality of quantum objects. In this famous experiment, particles pass one-by-one through a pair of slits and are detected on a distant screen. A distinct wave-like pattern emerges after many discrete particle impacts as if each particle is passing through both slits and interfering with itself. Here we present a temporally- and spatially-resolved measurement of the double-slit interference pattern using single photons. We send single photons through a birefringent double-slit apparatus and use a linear array of single-photon detectors to observe the developing interference pattern. The analysis of the buildup allows us to compare quantum mechanics and the corpuscular model, which aims to explain the mystery of single-particle interference. Finally, we send one photon from an entangled pair through our double-slit setup and show the dependence of the resulting interference pattern on the twin photon's measured state. Our results provide new insight into the dynamics of the buildup process in the double-slit experiment, and can be used as a valuable resource in quantum information applications.

  15. SLIT: indications, follow-up, and management.

    PubMed

    Dávila, I; Navarro, A; Domínguez-Ortega, J; Alonso, A; Antolín-Amérigo, D; Diéguez, M C; González-Mancebo, E; Martíns, C; Martínez, C; Núñez, B; Prior, N; Rechel, M; Rosado, A; Ruiz-Hornillos, J; Sansosti, A; Torrecillas, M; Jerez, M J

    2014-01-01

    Specific sublingual immunotherapy (SLIT) has been proved to be a safe and effective approach in respiratory allergy. However, further research is required on aspects such as patient selection, use of optimal dosing, effects on asthma, long-term effects, and management of adverse reactions. In addition, the widely heterogeneous nature of studies on SLIT performed to date and the application of the criteria for subcutaneous immunotherapy make it difficult for the prescribing clinician to draw accurate and useful conclusions. Therefore, the QUASAR Group (QUality in the Administration of SLIT in Allergic Rhinitis), which comprises allergologists with broad clinical experience in SLIT, investigated the latest research findings and available data on this approach. Working parties were formed in 3 different categories: selection of candidates for SLIT, treatment efficacy, and adverse reactions. We performed a PubMed search for articles that were representative of each category and found 850. From these, we finally selected 266 articles, which were reviewed to retrieve data on SLIT. Evidence for each clinical question was graded according to the Oxford classification. The resulting text was evaluated on 3 occasions by all the members of the group until the final version was agreed upon. In this version, we review available evidence on SLIT, particularly with pollens, which is the subject of most articles. In areas where evidence is insufficient, an alternative agreed upon by the members of the QUASAR group is presented. Finally, we propose algorithms for selecting candidates for SLIT and for management of adverse events.

  16. Design of decoupled dual servo stage with voice coil motor and linear motor for XY long stroke ultra-precision scanning system

    NASA Astrophysics Data System (ADS)

    Kim, Ki-Hyun; Choi, Young-Man; Gweon, Dae-Gab; Hong, Dong-Pyo; Kim, Koung-Suk; Lee, Suk-Won; Lee, Moon-Gu

    2005-12-01

    A decoupled dual servo (DDS) stage for ultra-precision scanning system is introduced in this paper. The proposed DDS consists of a 3 axis fine stage for handling and carrying workpieces and a XY coarse stage. Especially, the DDS uses three voice coil motors (VCM) as a planar actuation system of the fine stage to reduce the disturbances due to any mechanical connections with its coarse stage. VCMs are governed by Lorentz law. According to the law and its structure, there are no mechanical connections between coils and magnetic circuits. Moreover, the VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about 5mm2. To break that hurdle, the coarse stage with linear motors is used for the fine stage to move about 200mm2. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. Using MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. For linear motors, Halbach magnet linear motor is proposed and optimally designed in this paper. In addition, for their smooth movements without any frictions, guide systems of the DDS are composed of air bearings. And then, precisely to get their positions, linear scales with 0.1um resolution are used for the coarse's XY motions and plane mirror laser interferometers with 20nm for the fine's XYθz. On scanning, the two stages have same trajectories and are controlled. The control algorithm is Parallel method. The embodied ultra-precision scanning system has about 100nm tracking error and in-positioning stability.

  17. Slit-Robo signaling in ocular angiogenesis.

    PubMed

    Chen, Haoyu; Zhang, Mingzhi; Tang, Shibo; London, Nyall R; Li, Dean Y; Zhang, Kang

    2010-01-01

    Slit-Robo signaling was firstly discovered as a major repellent pathway at the midline of the central nervous system. Intense investigation found that this pathway also plays an important role in other biological process including angiogenesis. Robo4 is the vascular endothelial cell specific member of Robo family. It was found that Slit-Robo signaling can inhibit endothelial cell migration, tube formation and vascular permeability. Slit-Robo signaling also plays an important role in embryonic and tumor angiogenesis. In animal model of ocular angiogenesis, addition of Slit inhibited laser induced choroidal neovascularization, oxygen induced retinopathy and VEGF induced retinal permeability in a Robo4 dependent manner. Recent data demonstrates that Robo1 and Robo4 form a heterodimer in endothelial cells, The role of this heterodimer in counteracting VEGF signaling is unknown. Further investigation is required to better understand Slit-Robo signaling and develop novel therapy for angiogenesis.

  18. Radiation absorbed from dental implant radiography: a comparison of linear tomography, CT scan, and panoramic and intra-oral techniques

    SciTech Connect

    Clark, D.E.; Danforth, R.A.; Barnes, R.W.; Burtch, M.L. )

    1990-01-01

    Absorbed radiation dose in bone marrow, thyroid, salivary gland, eye, and skin entrance was determined by placement of lithium fluoride thermoluminescent dosimeters (TLD's) at selected anatomical sites within and on a human-like x-ray phantom. The phantom was exposed to radiation from linear tomographic and computer-assisted tomographic (CT) simulated dental implant radiographic examinations. The mean dose was determined for each anatomical site. Resulting dose measurements from linear tomography and computer-assisted tomography are compared with reported panoramic and intra-oral doses. CT examination delivered the greatest dose, while linear tomography was generally lowest. Panoramic and intra-oral doses were similar to those of linear tomography.

  19. High resolution digital holographic microscopy with a wide field of view based on a synthetic aperture technique and use of linear CCD scanning.

    PubMed

    Di, Jianglei; Zhao, Jianlin; Jiang, Hongzhen; Zhang, Peng; Fan, Qi; Sun, Weiwei

    2008-10-20

    Theoretical analysis shows that, to improve the resolution and the range of the field of view of the reconstructed image in digital lensless Fourier transform holography, an effective solution is to increase the area and the pixel number of the recorded digital hologram. A new approach based on the synthetic aperture technique and use of linear CCD scanning is presented to obtain digital holographic images with high resolution and a wide field of view. By using a synthetic aperture technique and linear CCD scanning, we obtained digital lensless Fourier transform holograms with a large area of 3.5 cm x 3.5 cm (5000 x 5000 pixels). The numerical reconstruction of a 4 mm object at a distance of 14 cm by use of a Rayleigh-Sommerfeld integral shows that a theoretically minimum resolvable distance of 2.57 microm can be achieved at a wavelength of 632.8 nm. The experimental results are consistent with the theoretical analysis.

  20. Slit Diaphragms Contain Tight Junction Proteins

    PubMed Central

    Fukasawa, Hirotaka; Bornheimer, Scott; Kudlicka, Krystyna; Farquhar, Marilyn G.

    2009-01-01

    Slit diaphragms are essential components of the glomerular filtration apparatus, as changes in these junctions are the hallmark of proteinuric diseases. Slit diaphragms, considered specialized adherens junctions, contain both unique membrane proteins (e.g., nephrin, podocin, and Neph1) and typical adherens junction proteins (e.g., P-cadherin, FAT, and catenins). Whether slit diaphragms also contain tight junction proteins is unknown. Here, immunofluorescence, immunogold labeling, and cell fractionation demonstrated that rat slit diaphragms contain the tight junction proteins JAM-A (junctional adhesion molecule A), occludin, and cingulin. We found these proteins in the same protein complexes as nephrin, podocin, CD2AP, ZO-1, and Neph1 by cosedimentation, coimmunoprecipitation, and pull-down assays. PAN nephrosis increased the protein levels of JAM-A, occludin, cingulin, and ZO-1 several-fold in glomeruli and loosened their attachment to the actin cytoskeleton. These data extend current information about the molecular composition of slit diaphragms by demonstrating the presence of tight junction proteins, although slit diaphragms lack the characteristic morphologic features of tight junctions. The contribution of these proteins to the assembly of slit diaphragms and potential signaling cascades requires further investigation. PMID:19478094

  1. Colloid-polymer mixtures under slit confinement.

    PubMed

    Pérez-Ramírez, Allan; Figueroa-Gerstenmaier, Susana; Odriozola, Gerardo

    2017-03-14

    We report a NVT molecular dynamic study of colloid-polymer mixtures under slit confinement. For this purpose, we are employing the Asakura-Oosawa model for studying colloidal particles, polymer coils, and hard walls as the external confining field. The colloid-polymer size ratio, q, is varied in the range 1⩾q⩾0.4 and the confinement distance, H, in 10σc⩾H⩾3σc, σc being the colloidal diameter. Vapor-liquid coexistence properties are assessed, from which phase diagrams are built. The obtained data fulfill the corresponding states law for a constant H when q is varied. The shift of the polymer and colloidal chemical potentials of coexistence follows a linear relationship with (H-σc)(-1) for H≳4σc. The confined vapor-liquid interfaces can be fitted with a semicircular line of curvature (H-σc)(-1), from which the contact angle can be obtained. We observe complete wetting of the confining walls for reservoir polymer concentrations above and close to the critical value, and partial wetting for reservoir polymer concentrations above and far from it.

  2. Colloid-polymer mixtures under slit confinement

    NASA Astrophysics Data System (ADS)

    Pérez-Ramírez, Allan; Figueroa-Gerstenmaier, Susana; Odriozola, Gerardo

    2017-03-01

    We report a NVT molecular dynamic study of colloid-polymer mixtures under slit confinement. For this purpose, we are employing the Asakura-Oosawa model for studying colloidal particles, polymer coils, and hard walls as the external confining field. The colloid-polymer size ratio, q, is varied in the range 1 ⩾q ⩾0.4 and the confinement distance, H, in 10 σc ⩾H ⩾3 σc , σc being the colloidal diameter. Vapor-liquid coexistence properties are assessed, from which phase diagrams are built. The obtained data fulfill the corresponding states law for a constant H when q is varied. The shift of the polymer and colloidal chemical potentials of coexistence follows a linear relationship with (H-σc ) -1 for H ≳4 σc . The confined vapor-liquid interfaces can be fitted with a semicircular line of curvature (H-σc ) -1, from which the contact angle can be obtained. We observe complete wetting of the confining walls for reservoir polymer concentrations above and close to the critical value, and partial wetting for reservoir polymer concentrations above and far from it.

  3. Vapor-liquid critical and interfacial properties of square-well fluids in slit pores.

    PubMed

    Jana, Subimal; Singh, Jayant K; Kwak, Sang Kyu

    2009-06-07

    Vapor-liquid phase equilibria of square-well (SW) fluids of variable interaction range: lambdasigma=1.25, 1.75, 2.0, and 3.0 in hard slit pores are studied by means of grand-canonical transition-matrix Monte Carlo (GC-TMMC) simulation. Critical density under confinement shows an oscillatory behavior as slit width, H, reduced from 12sigma to 1sigma. Two linear regimes are found for the shift in the critical temperature with the inverse in the slit width. The first regime is seen for H>2.0sigma with linear increase in the slope of shift in the critical temperature against inverse slit width with increasing interaction range. Subsequent decrease in H has little consequence on the critical temperature and it remains almost constant. Vapor-liquid surface tensions of SW fluids of variable well extent in a planar slit pore of variable slit width are also reported. GC-TMMC results are compared with that from slab based canonical Monte Carlo and molecular dynamics techniques and found to be in good agreement. Although, vapor-liquid surface tension under confinement is found to be lower than the bulk surface tension, the behavior of surface tension as a function of temperature is invariant with the variable pore size. Interfacial width, xi, calculated using a hyperbolic function increases with decreasing slit width at a given temperature, which is contrary to what is being observed recently for cylindrical pores. Inverse scaled interfacial width (xi/H), however, linearly increases with increase in the scaled temperature (T(c,bulk)-T)/T(c,bulk).

  4. Multilayer hexagonal silicon forming in slit nanopore.

    PubMed

    He, Yezeng; Li, Hui; Sui, Yanwei; Qi, Jiqiu; Wang, Yanqing; Chen, Zheng; Dong, Jichen; Li, Xiongying

    2015-10-05

    The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties.

  5. Video equipment recommendations for slit lamp videography.

    PubMed

    Hammack, G G

    1991-08-01

    Current developments in video technology have made videotaping through a slit lamp a useful capability available at a more reasonable cost. The technical basis of equipment needed to select or design an apparatus for slit lamp videography is reviewed. As an overview, the optimum slit lamp video apparatus would have the following criteria; the slit lamp should have zoom optics and rheostat illumination, the beam splitter should be a mirror or 70/30 type, the camera should have maximal light sensitivity (101ux) with reasonable resolution (greater than 300 lines). The recorder should be SP-Umatic or Super VHS for documentation, or consumer VHS for patient education, and the monitor should be a professional 13- or 15-inch monitor.

  6. Handheld three-dimensional pipe measurement system with a slit-ray projector

    NASA Astrophysics Data System (ADS)

    Kawasue, Kikuhito; Komatsu, Takayuki; Yoshida, Kumiko

    2013-03-01

    We propose a point cloud data acquisition system that employs slit ray projection. In this system, a slit laser projector and a high-resolution CCD camera are connected to a Microsoft Kinect Sensor. The system is sufficiently compact that it can be hand held. In measurements of pipes, the user directs the laser slit ray at the measurement target. Kinect then detects point cloud data while the CCD camera simultaneously detects the laser streak generated on the target surface. The user manually scans the system by directing the laser slit ray along the measurement pipe. The point cloud data obtained by Kinect is used to determine the movement of the system by adjusting overlapping data in consecutive frames using the ICP (Iterative Closest Point) algorithm. This permits the system to be freely scanned. The pipe cross section is estimated from data obtained by the slit-ray projection method. The three-dimensional shape of the pipe is constructed on a computer from the obtained cross sections.

  7. Bypassing of stems versus linear base-by-base inspection of mammalian mRNAs during ribosomal scanning.

    PubMed

    Abaeva, Irina S; Marintchev, Assen; Pisareva, Vera P; Hellen, Christopher U T; Pestova, Tatyana V

    2011-01-05

    Initiation codon selection in eukaryotes involves base-by-base inspection of the 5'-untranslated region of mRNA by scanning ribosomal 43S preinitiation complexes. We employed in vitro reconstitution to investigate factor requirements for this process and report that in the absence of eIF1 and DHX29, eIFs 4A, 4B and 4G promote efficient bypassing of stable stems by scanning 43S complexes and formation of 48S initiation complexes on AUG codons immediately upstream and downstream of such stems, without their unwinding. However, intact stems are not threaded through the entire mRNA Exit channel of the 40S subunit, resulting in incorrect positioning of mRNA upstream of the ribosomal P site in 48S complexes formed on AUG codons following intact stems, which renders them susceptible to dissociation by eIF1. In 48S complexes formed on AUG codons preceding intact stems, the stems are accommodated in the A site. Such aberrant complexes are destabilized by DHX29, which also ensures that mRNA enters the mRNA-binding cleft in a single-stranded form and therefore undergoes base-by-base inspection during scanning.

  8. Linear least-squares fit evaluation of series of analytical spectra from planar defects: extension and possible implementations in scanning transmission electron microscopy.

    PubMed

    Walther, T

    2006-08-01

    In a previous paper, a new technique was introduced to determine the chemistry of crystallographically well-defined planar defects (such as straight interfaces, grain boundaries, twins, inversion or antiphase domain boundaries) in the presence of homogeneous solute segregation or selective doping. The technique is based on a linear least-squares fit using series of analytical (electron energy-loss or energy-dispersive X-ray) spectra acquired in a transmission electron microscope that is operated in nano-probe mode with the planar defect centred edge-on. First, additional notes on the use of proper k-factors and determination of Gibbsian excess segregation are given in this note. Using simulated data sets, it is shown that the linear least-squares fit improves both the accuracy and the robustness to noise beyond that obtainable by independently repeated measurements. It is then shown how the method originally developed for a stationary nano-probe mode in transmission electron microscopy can be extended to a focused electron beam that scans a square region in scanning transmission electron microscopy. The necessary modifications to scan geometry and corresponding numerical evaluation are described, and three different practical implementations are proposed.

  9. Feature profile control and the influence of scan artifacts

    NASA Astrophysics Data System (ADS)

    Dare, Richard; Rowland, Paul R.; Zavecz, Terrence E.

    2005-05-01

    Competitive high volume semiconductor manufacturing yields require that critical feature profiles be continually monitored for uniformity and production control. Historically this has involved long and tedious analyses of Scanning Electron Microscope (SEM) photos that resulted in an average feature profile or a qualitative comparison of a matrix of black and white images. Many factors influence profiles including wafer flatness, focus and film thicknesses. Characterizing profile uniformity as a function of these parameters not only stabilizes high product yields but also significantly reduces the time spent in problem aversion and solution discovery. Scatterometry uniquely provides the combination of feature metrics and spatial coverage needed to monitor production profiles. The vast amount of data gathered by these systems is not well handled by classic statistical methods. A more practical approach taken by the authors is to apply spatial models to the profile data to determine the relative stability and contributions of film, substrate and the exposure tool to process perturbations. Recent work performed by Agere and TEA Systems is shown to be capable of quantitatively modeling the relative contributions of lens slit, reticle-scan and lens degradation to feature size and side-wall angle (SWA). This work describes the models used and the slit-and-scan contributions that are unique for each exposure tool. Finally it is shown that the direction and linearity of the reticle scan can be a contributing factor to the feature profile error budget with direct influence production image stability.

  10. Diagnostic Accuracy of Ultrasound B scan using 10 MHz linear probe in ocular trauma;results from a high burden country

    PubMed Central

    Shazlee, Muhammad Kashif; Ali, Muhammad; SaadAhmed, Muhammad; Hussain, Ammad; Hameed, Kamran; Lutfi, Irfan Amjad; Khan, Muhammad Tahir

    2016-01-01

    Objective: To study the diagnostic accuracy of Ultrasound B scan using 10 MHz linear probe in ocular trauma. Methods: A total of 61 patients with 63 ocular injuries were assessed during July 2013 to January 2014. All patients were referred to the department of Radiology from Emergency Room since adequate clinical assessment of the fundus was impossible because of the presence of opaque ocular media. Based on radiological diagnosis, the patients were provided treatment (surgical or medical). Clinical diagnosis was confirmed during surgical procedures or clinical follow-up. Results: A total of 63 ocular injuries were examined in 61 patients. The overall sensitivity was 91.5%, Specificity was 98.87%, Positive predictive value was 87.62 and Negative predictive value was 99%. Conclusion: Ultrasound B-scan is a sensitive, non invasive and rapid way of assessing intraocular damage caused by blunt or penetrating eye injuries. PMID:27182245

  11. Non-linear optical study of BODIPY-benzimidazole conjugate by solvatochromic, Z-scan and theoretical methods

    NASA Astrophysics Data System (ADS)

    Thakare, Shrikant S.; Sreenath, Mavila C.; Chitrambalam, Subramaniyan; Joe, Isaac H.; Sekar, Nagaiyan

    2017-02-01

    BODIPY chromophore flanked with the benzimidazole moiety at 2-position has been investigated for its nonlinear optical (NLO) properties. Charge transfer character developed by the unsymmetrical substitution on the molecular framework and the solvatochromic behaviour of this dye inspired us to study its NLO characteristics. NLO response has been measured using solvatochromic method as well as the Z scan technique. The values obtained for nonlinear absorption coefficient (β) and third order susceptibility χ(3) are -7.45 × 10-12 and 3.85 × 10-13 respectively. Quantum chemical calculations have also been performed to estimate the NLO properties theoretically by using DFT method with three functionals viz B3LYP, BHHLYP and CAMB3LYP with 6-311 G (d,p) basis set. The results obtained from the DFT method are in well accordance with those produced from solvatochromic method.

  12. Ultra-fast 3D scanning and holographic illumination in non-linear microscopy using acousto-optic deflectors

    NASA Astrophysics Data System (ADS)

    Akemann, Walther; Ventalon, Cathie; Léger, Jean-François; Mathieu, Benjamin; Dieudonné, Stéphane; Blochet, Baptiste; Gigan, Sylvain; Bourdieu, Laurent

    2017-04-01

    Decoding of information in the brain requires the imaging of large neuronal networks using e.g. two-photon microscopy (TPM). Fast control of the focus in 3D can be achieved with phase shaping of the light beam using acoustooptic deflectors (AODs). However, beam shaping using AODs is not straightforward because of non-stationary of acousto-optic diffraction. Here, we demonstrated a new stable AOD-based phase modulator, which operates at a rate of up to about hundred kHz. It provides opportunity for 3D scanning in TPM with the possibility to correct aberrations independently for every focus position or to achieve refocusing of scattered photons in rapidly decorrelating tissues.

  13. PlexinA1 is a new Slit receptor and mediates axon guidance function of Slit C-terminal fragments.

    PubMed

    Delloye-Bourgeois, Céline; Jacquier, Arnaud; Charoy, Camille; Reynaud, Florie; Nawabi, Homaira; Thoinet, Karine; Kindbeiter, Karine; Yoshida, Yutaka; Zagar, Yvrick; Kong, Youxin; Jones, Yvonne E; Falk, Julien; Chédotal, Alain; Castellani, Valérie

    2015-01-01

    Robo-Slit and Plexin-Semaphorin signaling participate in various developmental and pathogenic processes. During commissural axon guidance in the spinal cord, chemorepulsion by Semaphorin3B and Slits controls midline crossing. Slit processing generates an N-terminal fragment (SlitN) that binds to Robo1 and Robo2 receptors and mediates Slit repulsive activity, as well as a C-terminal fragment (SlitC) with an unknown receptor and bioactivity. We identified PlexinA1 as a Slit receptor and found that it binds the C-terminal Slit fragment specifically and transduces a SlitC signal independently of the Robos and the Neuropilins. PlexinA1-SlitC complexes are detected in spinal cord extracts, and ex vivo, SlitC binding to PlexinA1 elicits a repulsive commissural response. Analysis of various ligand and receptor knockout mice shows that PlexinA1-Slit and Robo-Slit signaling have complementary roles during commissural axon guidance. Thus, PlexinA1 mediates both Semaphorin and Slit signaling, and Slit processing generates two active fragments, each exerting distinct effects through specific receptors.

  14. Analytical and Experimental Characterization of a Linear-Array Thermopile Scanning Radiometer for Geo-Synchronous Earth Radiation Budget Applications

    NASA Technical Reports Server (NTRS)

    Sorensen, Ira J.

    1998-01-01

    The Thermal Radiation Group, a laboratory in the department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently working towards the development of a new technology for cavity-based radiometers. The radiometer consists of a 256-element linear-array thermopile detector mounted on the wall of a mirrored wedgeshaped cavity. The objective of this research is to provide analytical and experimental characterization of the proposed radiometer. A dynamic end-to-end opto-electrothermal model is developed to simulate the performance of the radiometer. Experimental results for prototype thermopile detectors are included. Also presented is the concept of the discrete Green's function to characterize the optical scattering of radiant energy in the cavity, along with a data-processing algorithm to correct for the scattering. Finally, a parametric study of the sensitivity of the discrete Green's function to uncertainties in the surface properties of the cavity is presented.

  15. Oil droplet versus electron double slit diffraction

    NASA Astrophysics Data System (ADS)

    Jones, Eric; Lif, Adam; McGregor, Scot; Bach, Roger; Batelaan, Herman

    2012-06-01

    The double-slit experiments for photons and electrons are considered cornerstones of modern physics. Feynman's account of these experiments is one of the most popular. To get as close to Feynman's description of double-slit diffraction we did some experiments. This includes closing individual slits on demand, and taking a movie of the build-up of the diffraction pattern one particle at a time. In recent work done in Paris [1], macroscopic particle-wave duality with bouncing oil droplets was demonstrated for the first time ever. This may have implications for microscopic or quantum-mechanical particle-wave duality for electrons and photons. We will report on our attempts to reproduce the Paris results, and show new results of the individual droplet trajectories and how they compare to de Broglie-Bohm trajectories. [4pt] [1] Yves Couder and Emmanuel Fort, Phys. Rev. Lett. 97, 154101 (2006)

  16. Data processing for a multi-slit LWIR HSI spectrometer

    NASA Astrophysics Data System (ADS)

    Martin, Jacob A.; Meola, Joseph

    2016-09-01

    Preliminary testing of a three-slit prism-based spectrometer is presented to test means of exploiting data from a multi-slit spectrometer as well as some potential ways of dealing with complications that arise when using multiple slits. When using a multiple slit spectrometer to boost SNR there are two primary concerns: first, the spectral axis of each slit must be nearly identical to effective average and second, the image from each slit must be well-registered. Based on some of these complications it seems, given the current technology, the best operational mode is to use the sensor to increase area coverage.

  17. Resolution criteria in double-slit microscopic imaging experiments

    NASA Astrophysics Data System (ADS)

    You, Shangting; Kuang, Cuifang; Zhang, Baile

    2016-09-01

    Double-slit imaging is widely used for verifying the resolution of high-resolution and super-resolution microscopies. However, due to the fabrication limits, the slit width is generally non-negligible, which can affect the claimed resolution. In this paper we theoretically calculate the electromagnetic field distribution inside and near the metallic double slit using waveguide mode expansion method, and acquire the far-field image by vectorial Fourier optics. We find that the slit width has minimal influence when the illuminating light is polarized parallel to the slits. In this case, the claimed resolution should be based on the center-to-center distance of the double-slit.

  18. Efficiency Optimization of Slitted-Core Induction Motor

    NASA Astrophysics Data System (ADS)

    Yetgin, Asim Gökhan; Turan, Mustafa

    2014-01-01

    In this study, a 3kW squirrel cage induction motor having slits in stator and rotor teeth were examined. The slit depth and width in the 56 different slitted motor models were optimized with Finite Element Method Magnetics (FEMM) software by using Finite Elements Method (FEM). What value the depth and width of optimum slit should be was determined in order to obtain maximum motor efficiency in the new motor models created with the proposed slitted structure, and how the depth and width of slit could affect the performance of motor was demonstrated.

  19. Training package 1 for slitting data analysis

    SciTech Connect

    Prime, Michael Bruce

    2015-03-23

    This document and accompanying files are intended as a first training package on how to analyze slitting data. The end goal is to have Idaho National Laboratory (INL) personnel trained to analyze future slitting data taken in the INL Hot Cell on clad, Low-Enriched Uranium (LEU) fuel plates. This first data package will cover data analysis for a monolithic material (as compared to a layered material like the clad fuel plates). The additional issues for layered specimens will be covered in a future training package.

  20. 3D printed LED based on-capillary detector housing with integrated slit.

    PubMed

    Cecil, Farhan; Zhang, Min; Guijt, Rosanne M; Henderson, Alan; Nesterenko, Pavel N; Paull, Brett; Breadmore, Michael C; Macka, Mirek

    2017-05-01

    A 3D printed photometric detector body with integrated slit was fabricated to position a LED and photodiode either side of capillary tubing using a fused deposition modelling (FDM) printer. To make this approach suitable for capillaries down to 50 μm i.d. the dimension of the in-built slit is the critical element of the printed housing. The spatial orientation of the model for printing was found to significantly impact on the resolution of the structures and voids that can be printed. By designing a housing with a slit positioned in the XY plane in parallel with the print direction, the narrowest void (slit) that could be printed was 70 μm. The potential use of the 3D printed slit for photometric detection was characterised using tubing and capillary from 500 down to 50 μm i.d, demonstrating a linear response from 632 to 40 mAU. The effective pathlength and stray light varied from 383 to 22 μm and 3.8% - 50% for 500- 50 μm i.d tubing and capillary. The use of a V-shaped alignment feature allowed for easy and reliable positioning of the tubing inside the detector, as demonstrated by a RSD of 1.9% (n = 10) in peak height when repositioning the tubing between measurements using flow injection analysis (FIA). The performance of the 3D printed housing and 70 μm slit was benchmarked against a commercially available interface using the CE separation of Zn(2+) and Cu(2+) complexes with PAR. The limit of detection with the 3D printed slit was 6.8 and 4.5 μM and is 2.8 and 1.6 μM with the commercial interface.

  1. "Either-or" two-slit interference: stable coherent propagation of individual photons through separate slits.

    PubMed

    Alkon, D L

    2001-05-01

    In quantum theory, nothing that is observable, be it physical, chemical, or biological, is separable from the observer. Furthermore, ". all possible knowledge concerning that object is given by its wave function" (Wigner, E. 1967. Symmetries and Reflections. Indiana University Press, Bloomington, IN), which can only describe probabilities of future events. In physical systems, quantum mechanical probabilistic events that are microscopic must, in turn, account for macroscopic events that are associated with a greater degree of certainty. In biological systems, probabilistic statistical mechanical events, such as secretion of microscopic synaptic vesicles, must account for macroscopic postsynaptic potentials; probabilistic single-channel events sum to produce a macroscopic ionic current across a cell membrane; and bleaching of rhodopsin molecules (responsible for quantal potential "bumps") produces a photoreceptor generator potential. Among physical systems, a paradigmatic example of how quantum theory applies to the observation of events concerns the interactions of particles (e.g., photons, electrons) with the two-slit apparatus to generate an interference pattern from a single common light source. For two-slit systems that use two independent laser sources with brief (<1 ms) intervals of mutual coherence (Paul, H. 1986. Rev. Modern Phys. 58:209-231), each photon has been considered to arise from both beams and has a probability amplitude to pass through each of the two slits. Here, a single laser source two-slit interference system was constructed so that each photon has a probability amplitude to pass through only one or the other, but not both slits. Furthermore, all photons passing through one slit could be distinguished from all photons passing through the other slit before their passage. This "either-or" system produced a stable interference pattern indistinguishable from the interference produced when both slits were accessible to each photon. Because this

  2. "Either-or" two-slit interference: stable coherent propagation of individual photons through separate slits.

    PubMed Central

    Alkon, D L

    2001-01-01

    In quantum theory, nothing that is observable, be it physical, chemical, or biological, is separable from the observer. Furthermore, ". all possible knowledge concerning that object is given by its wave function" (Wigner, E. 1967. Symmetries and Reflections. Indiana University Press, Bloomington, IN), which can only describe probabilities of future events. In physical systems, quantum mechanical probabilistic events that are microscopic must, in turn, account for macroscopic events that are associated with a greater degree of certainty. In biological systems, probabilistic statistical mechanical events, such as secretion of microscopic synaptic vesicles, must account for macroscopic postsynaptic potentials; probabilistic single-channel events sum to produce a macroscopic ionic current across a cell membrane; and bleaching of rhodopsin molecules (responsible for quantal potential "bumps") produces a photoreceptor generator potential. Among physical systems, a paradigmatic example of how quantum theory applies to the observation of events concerns the interactions of particles (e.g., photons, electrons) with the two-slit apparatus to generate an interference pattern from a single common light source. For two-slit systems that use two independent laser sources with brief (<1 ms) intervals of mutual coherence (Paul, H. 1986. Rev. Modern Phys. 58:209-231), each photon has been considered to arise from both beams and has a probability amplitude to pass through each of the two slits. Here, a single laser source two-slit interference system was constructed so that each photon has a probability amplitude to pass through only one or the other, but not both slits. Furthermore, all photons passing through one slit could be distinguished from all photons passing through the other slit before their passage. This "either-or" system produced a stable interference pattern indistinguishable from the interference produced when both slits were accessible to each photon. Because this

  3. Polish device for FOCCoS/PFS slit system

    NASA Astrophysics Data System (ADS)

    de Oliveira, Antonio Cesar; de Oliveira, Ligia Souza; de Arruda, Marcio V.; Souza Marrara, Lucas; dos Santos, Leandro Henrique; Ferreira, Décio; dos Santos, Jesulino Bispo; de Paiva Vilaça, Rodrigo; Rosa, Josimar Aparecido; Sodré Junior, Laerte; de Oliveira, Claudia Mendes

    2014-07-01

    The Fiber Optical Cable and Connector System, "FOCCoS", for the Prime Focus Spectrograph, "PFS", is responsible for transporting light from the Subaru Telescope focal plane to a set of four spectrographs. Each spectrograph will be fed by a convex curved slit with 616 optical fibers organized in a linear arrangement. The slit frontal surface is covered with a special dark composite, made with refractory oxide, which is able to sustain its properties with minimum quantities of abrasives during the polishing process; this stability is obtained This stability is obtained by the detachment of the refractory oxide nanoparticles, which then gently reinforce gently the polishing process and increase its the efficiency. The surface roughness measured in several samples after high performance polishing was about 0.01 microns. Furthermore, the time for obtaining a polished surface with this quality is about 10 times less than the time required for polishing a brass, glass or ceramic surface of the same size. In this paper, we describe the procedure developed for high quality polishing of this type of slit. The cylindrical polishing described here, uses cylindrical concave metal bases on which glass paper is based. The polishing process consists to use grid sequences of 30μm, 12μm, 9μm, 5μm, 3μm, 1μm and, finally, a colloidal silica on a chemical cloth. To obtain the maximum throughput, the surface of the fibers should be polished in such a way that they are optically flat and free from scratches. The optical fibers are inspected with a microscope at all stages of the polishing process to ensure high quality. The efficiency of the process may be improved by using a cylindrical concave composite base as a substrate suitable for diamond liquid solutions. Despite this process being completely by hand, the final result shows a very high quality.

  4. Flow Through Surface Mounted Continuous Slits

    NASA Astrophysics Data System (ADS)

    Tariq, A.; Ali, M. A.; Gad-El-Hak, M.

    2014-11-01

    Ribs are used inside certain gas-turbine blades as passive devices to enhance heat transfer. Slits in those ribs are utilized to control the primary shear layer. The role of secondary flow through a continuous slit behind a surface mounted rib is investigated herein in a rectangular duct using hotwire anemometry and particle image velocimetry. Changing the open-area-ratio and the slit's location within the rib dominate the observed shear layer. The behavior of discrete Fourier modes of the velocity fluctuations generated by different configurations is explored. Two distinct flow mechanisms are observed in the rib's wake. Both mechanisms are explained on the basis of large-scale spectral peak in the shear layer. The results show the successful impact of changing the open-area-ratio by manipulating the small-scale vortices at the leeward corner of the rib, which is suspected to be the potential cause of surface ``hot spots'' in a variety of engineering devices with heat transfer. Eventually, the size and location of the slit are seen to be an additional parameter that can be used to control the fluid flow structures behind rib turbulators.

  5. Comment on 'Biphoton double-slit experiment'

    SciTech Connect

    Oriols, X.

    2005-01-01

    In a recent paper [Phys. Rev. A 68, 033803 (2003)] experimental results on a double-slit configuration with two entangled bosons are presented. The authors argue that their data contradicts the de Broglie-Bohm interpretation of quantum mechanics. In this Comment we show that this conclusion is incorrect.

  6. Measuring Slit Width and Separation in a Diffraction Experiment

    ERIC Educational Resources Information Center

    Gan, K. K.; Law, A. T.

    2009-01-01

    We present a procedure for measuring slit width and separation in single- and double-slit diffraction experiments. Intensity spectra of diffracted laser light are measured with an optical sensor (PIN diode). Slit widths and separations are extracted by fitting to the measured spectra. We present a simple fitting procedure to account for the…

  7. Measuring Slit Width and Separation in a Diffraction Experiment

    ERIC Educational Resources Information Center

    Gan, K. K.; Law, A. T.

    2009-01-01

    We present a procedure for measuring slit width and separation in single- and double-slit diffraction experiments. Intensity spectra of diffracted laser light are measured with an optical sensor (PIN diode). Slit widths and separations are extracted by fitting to the measured spectra. We present a simple fitting procedure to account for the…

  8. Full-field linear and nonlinear measurements using Continuous-Scan Laser Doppler Vibrometry and high speed Three-Dimensional Digital Image Correlation

    NASA Astrophysics Data System (ADS)

    Ehrhardt, David A.; Allen, Matthew S.; Yang, Shifei; Beberniss, Timothy J.

    2017-03-01

    Spatially detailed dynamic measurements of thin, lightweight structures can be difficult to obtain due to the structure's low mass and complicated deformations under certain loading conditions. If traditional contacting sensors, such as accelerometers, strain gauges, displacement transducers, etc., are used, the total number of measurement locations available is limited by the weight added and the effect each sensor has on the local stiffness of the contact area. Other non-contacting sensors, such as Laser Doppler Vibrometers (LDV), laser triangulation sensors, proximity sensors, etc., do not affect the dynamics of a structure, but are limited to single point measurements. In contrast, a few recently developed non-contacting measurement techniques have been shown to be capable of simultaneously measuring the response over a wide measurement field. Two techniques are considered here: Continuous-Scan Laser Doppler Vibrometry (CSLDV) and high speed Three-Dimensional Digital Image Correlation (3D DIC). With the use of these techniques, unprecedented measurement resolution can be achieved. In this work, the linear and nonlinear deformations of a clamped, nominally flat beam and plate under steady state sinusoidal loading will be measured using both techniques. In order to assess their relative merits, the linear natural frequencies, mode shapes, and nonlinear deformation shapes measured with each method are compared. Both measurement systems give comparable results in many cases, although 3D DIC is more accurate for spatially complex deformations at large amplitudes and CSLDV is more accurate at low amplitudes and when the spatial deformation pattern is simpler.

  9. Fluorescent scanning x-ray tomography with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Takeda, Tohoru; Maeda, Toshikazu; Yuasa, Tetsuya; Akatsuka, Takao; Ito, Tatsuo; Kishi, Kenichi; Wu, Jin; Kazama, Masahiro; Hyodo, Kazuyuki; Itai, Yuji

    1995-02-01

    Fluorescent scanning (FS) x-ray tomography was developed to detect nonradioactive tracer materials (iodine and gadolinium) in a living object. FS x-ray tomography consists of a silicon (111) channel cut monochromator, an x-ray shutter, an x-ray slit system and a collimator for detection, a scanning table for the target organ, and an x-ray detector with pure germanium. The minimal detectable dose of iodine in this experiment was 100 ng in a volume of 2 mm3 and a linear relationship was shown between the photon counts of a fluorescent x ray and the concentration of iodine contrast material. A FS x-ray tomographic image was clearly obtained with a phantom.

  10. Polarization dependent color switching by extra-ordinary transmission in H-slit plasmonic metasurface

    SciTech Connect

    Mandal, P.; Anantha Ramakrishna, S.; Patil, Raj; Venu Gopal, Achanta

    2013-12-14

    An array of H-shaped subwavelength slits in a plasmonic film has a polarization dependent extra-ordinary transmission due to shape anisotropy. Non-overlapping extra-ordinary transmission bands for the orthogonal linear polarization states of the input light are used to demonstrate a polarization dependent color switch. The fabricated array of submicron sized H-slits on a gold film displayed two transmission bands for the linear x- and y-polarized light at visible (650–850 nm) and near-infra-red (1150–1450 nm) bands, respectively. The relative transmitted light in these two bands can be controlled by changing the linear polarization state of the input radiation from 0° to 90°.

  11. Development and Preliminary Testing of a High Precision Long Stroke Slit Change Mechanism for the SPICE Instrument

    NASA Technical Reports Server (NTRS)

    Paciotti, Gabriel; Humphries, Martin; Rottmeier, Fabrice; Blecha, Luc

    2014-01-01

    In the frame of ESA's Solar Orbiter scientific mission, Almatech has been selected to design, develop and test the Slit Change Mechanism of the SPICE (SPectral Imaging of the Coronal Environment) instrument. In order to guaranty optical cleanliness level while fulfilling stringent positioning accuracies and repeatability requirements for slit positioning in the optical path of the instrument, a linear guiding system based on a double flexible blade arrangement has been selected. The four different slits to be used for the SPICE instrument resulted in a total stroke of 16.5 mm in this linear slit changer arrangement. The combination of long stroke and high precision positioning requirements has been identified as the main design challenge to be validated through breadboard models testing. This paper presents the development of SPICE's Slit Change Mechanism (SCM) and the two-step validation tests successfully performed on breadboard models of its flexible blade support system. The validation test results have demonstrated the full adequacy of the flexible blade guiding system implemented in SPICE's Slit Change Mechanism in a stand-alone configuration. Further breadboard test results, studying the influence of the compliant connection to the SCM linear actuator on an enhanced flexible guiding system design have shown significant enhancements in the positioning accuracy and repeatability of the selected flexible guiding system. Preliminary evaluation of the linear actuator design, including a detailed tolerance analyses, has shown the suitability of this satellite roller screw based mechanism for the actuation of the tested flexible guiding system and compliant connection. The presented development and preliminary testing of the high-precision long-stroke Slit Change Mechanism for the SPICE Instrument are considered fully successful such that future tests considering the full Slit Change Mechanism can be performed, with the gained confidence, directly on a

  12. Slit/Robo pathway: a promising therapeutic target for cancer.

    PubMed

    Gara, Rishi K; Kumari, Sonam; Ganju, Aditya; Yallapu, Murali M; Jaggi, Meena; Chauhan, Subhash C

    2015-01-01

    Axon guidance molecules, slit glycoprotein (Slit) and Roundabout receptor (Robo), have implications in the regulation of physiological processes. Recent studies indicate that Slit and Robo also have important roles in tumorigenesis, cancer progression and metastasis. The Slit/Robo pathway can be considered a master regulator for multiple oncogenic signaling pathways. Herein, we provide a comprehensive review on the role of these molecules and their associated signaling pathways in cancer progression and metastasis. Overall, the current available data suggest that the Slit/Robo pathway could be a promising target for development of anticancer drugs.

  13. [Remote Slit Lamp Microscope Consultation System Based on Web].

    PubMed

    Chen, Junfa; Zhuo, Yong; Liu, Zuguo; Chen, Yanping

    2015-11-01

    To realize the remote operation of the slit lamp microscope for department of ophthalmology consultation, and visual display the real-time status of remote slit lamp microscope, a remote slit lamp microscope consultation system based on B/S structure is designed and implemented. Through framing the slit lamp microscope on the website system, the realtime acquisition and transmission of remote control and image data is realized. The three dimensional model of the slit lamp microscope is established and rendered on the web by using WebGL technology. The practical application results can well show the real-time interactive of the remote consultation system.

  14. Double-slit experiment in momentum space

    NASA Astrophysics Data System (ADS)

    Ivanov, I. P.; Seipt, D.; Surzhykov, A.; Fritzsche, S.

    2016-08-01

    Young's classic double-slit experiment demonstrates the reality of interference when waves and particles travel simultaneously along two different spatial paths. Here, we propose a double-slit experiment in momentum space, realized in the free-space elastic scattering of vortex electrons. We show that this process proceeds along two paths in momentum space, which are well localized and well separated from each other. For such vortex beams, the (plane-wave) amplitudes along the two paths acquire adjustable phase shifts and produce interference fringes in the final angular distribution. We argue that this experiment can be realized with the present-day technology. We show that it gives experimental access to the Coulomb phase, a quantity which plays an important role in all charged particle scattering but which usual scattering experiments are insensitive to.

  15. F2 Boundary Layer Measurement in a Chemical Laser Slit Nozzle Flow.

    DTIC Science & Technology

    1983-02-15

    detector assembly mounted on top of the test 9 *Fig. 2. Experimental array used in measurements across jet TRANSLATION STAGE ASSEMBLY CaF...N2PUG Fig. 3. Slit nozzle F2 absorption scanning experiment 10 --’ -- section. The 450 folding mirror is mounted on a translation stage controll- able...from outside the test section via flexible coupling cable for micrometer movement across the jets. In addition, the mirrur mount provides the mirror

  16. Polarization and spectral action of narrow slit

    NASA Astrophysics Data System (ADS)

    Oleksyuk, M. V.; Felde, Ch. V.; Polyanskii, P. V.

    2012-01-01

    Experimental study of diffraction of coherent (laser, completely polarized) and incoherent (temporal, polychromatic, unpolarized) light radiation at slits whose width is restricted by a few wavelengths is made. It is shown that for diffraction at the edge of metallic half-plane screen, the angular dependences of diffraction field intensity are considerably different for orientation of the electric field vector parallel and perpendicular to the screen edge, so that metallic screen causes polarization action on the probing beam. It is shown that as the width of a slit formed by two metallic half-planes becomes less than ten wavelengths (being left larger than a wavelength), as the polarization effect is considerable even for the forward direction, i.e. for the zero diffraction angle. It causes also spectral effect, if polychromatic radiation diffracts at narrow slit at metallic screen. Namely, one observes pronounced blue shift of the maximum of the spectral distribution of the forward diffracted polychromatic ('white-light') beam. We apply for the first time the Berry's chromascopic technique for experimental data processing to elucidate such diffraction induced spectral changes.

  17. Polarization and spectral action of narrow slit

    NASA Astrophysics Data System (ADS)

    Oleksyuk, M. V.; Felde, Ch. V.; Polyanskii, P. V.

    2011-09-01

    Experimental study of diffraction of coherent (laser, completely polarized) and incoherent (temporal, polychromatic, unpolarized) light radiation at slits whose width is restricted by a few wavelengths is made. It is shown that for diffraction at the edge of metallic half-plane screen, the angular dependences of diffraction field intensity are considerably different for orientation of the electric field vector parallel and perpendicular to the screen edge, so that metallic screen causes polarization action on the probing beam. It is shown that as the width of a slit formed by two metallic half-planes becomes less than ten wavelengths (being left larger than a wavelength), as the polarization effect is considerable even for the forward direction, i.e. for the zero diffraction angle. It causes also spectral effect, if polychromatic radiation diffracts at narrow slit at metallic screen. Namely, one observes pronounced blue shift of the maximum of the spectral distribution of the forward diffracted polychromatic ('white-light') beam. We apply for the first time the Berry's chromascopic technique for experimental data processing to elucidate such diffraction induced spectral changes.

  18. Three-dimensional dental cast analyzing system using laser scanning.

    PubMed

    Kuroda, T; Motohashi, N; Tominaga, R; Iwata, K

    1996-10-01

    The purpose of this article is to introduce the outline of our newly developed three-dimensional dental cast analyzing system with laser scanning, and its preliminary clinical applications. The system is composed of a measuring device with a slit-ray laser projector and two sets of coupled charged devised video cameras, an image processing unit, a 16-bit personal computer as a controller, and an engineering workstation as a post processor. The dental cast is projected and scanned with a slit-ray laser beam. The raster coordinates of the target are determined with an image processor. Triangulation is applied to determine the location of each point. Generation of three-dimensional graphics of the dental cast takes approximately 40 minutes. About 90,000 sets of X, Y, Z coordinates are stored in the main memory of the microcomputer. The measurement error is less than 0.05 mm. Besides the conventional linear and angular measurements of the dental cast, we are also able to demonstrate the size of the palatal surface area and the volume of the oral cavity. The advantage of this system is that it facilitates the otherwise complicated and time-consuming mock surgery necessary for treatment planning in orthognathic surgery.

  19. Third order optical non-linear (Z-scan), birefringence, photoluminescence, mechanical and etching studies on melaminium levulinate monohydrate (MLM) single crystal for optical device applications

    NASA Astrophysics Data System (ADS)

    Sivakumar, N.; Anbalagan, G.

    2016-10-01

    Z-scan studies on the grown crystal was investigated by diode-pumped Nd; YAG laser. Nonlinear refractive index (n2) and third-order nonlinear optical susceptibility (χ3) values of MLM were found to be -1.0 × 10-8 cm2/W and 1.36 × 10-6 esu respectively. Powder X-ray diffraction analysis depicted that the crystal belongs to monoclinic system with space group P21/c. Birefringence study revealed the optical dispersion behavior of MLM crystal. Linear refractive index on (10-1) plane was measured by prism coupling technique and was estimated to be 1.4705. Hardness study was carried out along three different planes which exhibit hardness anisotropy of 41.11%. Meyer's index values of the grown crystal for the (10-1), (010) and (111) planes were found to be 2.39, 2.61 and 2.04 respectively. Etching studies on the prominent (10-1) growth plane was explained by two dimensional layer growth mechanisms. Photoluminescence study was performed on MLM crystal to explore its efficacy towards optical device fabrications.

  20. Range Sensing By Projecting Multiple Slits With Random Cuts

    NASA Astrophysics Data System (ADS)

    Maruyama, Minoru; Abe, Shigeru

    1990-04-01

    In this paper, we describe a range sensing method by projecting a single pattern of multiple slits. To obtain 3D data by projecting a single pattern, certain codes for identifying each slit must be contained in the patten. In our method, random dots are used to identify each slit. The random dots are given as randomly distributed cuts on each slit. Thus, each slit is divided into many small line segments and using these segments as features, stereo matching is carried out to obtain 3D data. Using adjacent relations among slit-segments, the false matches are reduced and segment pairs, whose adjacent segments also correspond with each other, are extracted and considered to be correct matches. Then, from the resultant matches, the correspondence is propagated by utilizing the adjacency relationships to get an entire range image.

  1. Coevolution of axon guidance molecule Slit and its receptor Robo.

    PubMed

    Yu, Qi; Li, Xiao-Tong; Zhao, Xiao; Liu, Xun-Li; Ikeo, Kazuho; Gojobori, Takashi; Liu, Qing-Xin

    2014-01-01

    Coevolution is important for the maintenance of the interaction between a ligand and its receptor during evolution. The interaction between axon guidance molecule Slit and its receptor Robo is critical for the axon repulsion in neural tissues, which is evolutionarily conserved from planarians to humans. However, the mechanism of coevolution between Slit and Robo remains unclear. In this study, we found that coordinated amino acid changes took place at interacting sites of Slit and Robo by comparing the amino acids at these sites among different organisms. In addition, the high level correlation between evolutionary rate of Slit and Robo was identified in vertebrates. Furthermore, the sites under positive selection of slit and robo were detected in the same lineage such as mosquito and teleost. Overall, our results provide evidence for the coevolution between Slit and Robo.

  2. Boltzmann-Shannon entropy and the double-slit experiment

    NASA Astrophysics Data System (ADS)

    Norwich, Kenneth H.

    2016-11-01

    We study the Boltzmann-Shannon entropy lost (information gained) by the observer in a double-slit experiment when the slit taken by a photon is known, and when the corresponding entropy gained by the photon at the level of the screen can be calculated. Using a Gedanken experiment involving infinitesimal slits and a distant cylindrical screen, entropy values assume a very simple form. The entropy changes (at the slit and screen) are found to be equal in magnitude and opposite in sign, and correspond to the minimum change permitted by Heisenberg's Uncertainty Principle. Moreover, when welcher Weg information is knowable a priori, we see that the "cost" of this information (knowing which slit is taken) is reversion to a single slit pattern.

  3. Resolution criteria in double-slit microscopic imaging experiments

    PubMed Central

    You, Shangting; Kuang, Cuifang; Zhang, Baile

    2016-01-01

    Double-slit imaging is widely used for verifying the resolution of high-resolution and super-resolution microscopies. However, due to the fabrication limits, the slit width is generally non-negligible, which can affect the claimed resolution. In this paper we theoretically calculate the electromagnetic field distribution inside and near the metallic double slit using waveguide mode expansion method, and acquire the far-field image by vectorial Fourier optics. We find that the slit width has minimal influence when the illuminating light is polarized parallel to the slits. In this case, the claimed resolution should be based on the center-to-center distance of the double-slit. PMID:27640808

  4. MUSE: the Multi-Slit Solar Explorer

    NASA Astrophysics Data System (ADS)

    Tarbell, Theodore D.; De Pontieu, Bart

    2017-08-01

    The Multi-Slit Solar Explorer is a proposed Small Explorer mission for studying the dynamics of the corona and transition region using both conventional and novel spectral imaging techniques. The physical processes that heat the multi-million degree solar corona, accelerate the solar wind and drive solar activity (CMEs and flares) remain poorly known. A breakthrough in these areas can only come from radically innovative instrumentation and state-of-the-art numerical modeling and will lead to better understanding of space weather origins. MUSE’s multi-slit coronal spectroscopy will use a 100x improvement in spectral raster cadence to fill a crucial gap in our knowledge of Sun-Earth connections; it will reveal temperatures, velocities and non-thermal processes over a wide temperature range to diagnose physical processes that remain invisible to current or planned instruments. MUSE will contain two instruments: an EUV spectrograph (SG) and EUV context imager (CI). Both have similar spatial resolution and leverage extensive heritage from previous high-resolution instruments such as IRIS and the HiC rocket payload. The MUSE investigation will build on the success of IRIS by combining numerical modeling with a uniquely capable observatory: MUSE will obtain EUV spectra and images with the highest resolution in space (1/3 arcsec) and time (1-4 s) ever achieved for the transition region and corona, along 35 slits and a large context FOV simultaneously. The MUSE consortium includes LMSAL, SAO, Stanford, ARC, HAO, GSFC, MSFC, MSU, ITA Oslo and other institutions.

  5. [Comparison of the effectiveness of pulmonary veins isolation vs linear radiofrequency ablation in paroxysmal atrial fibrillation patients using either mathematical scanning or clinical approach].

    PubMed

    Ardashev, A V; Mazurov, M E; Kaliuzhnyĭ, I M; Zheliakov, E G; Belenkov, Iu N

    2012-01-01

    to compare clinical results of linear ablation vs. PVI approach in patients with paroxysmal AF and to estimate theoretical probability of 4-waves re-entry to eliminate as a results of the both ablative techniques formatting by means left atrial geometry two-dimensional mathematical modeling. Clinical phase. Study was conducted on 20 pts (6 women, 51,4±13,6 years of age) with paroxysmal AF underwent index RFA. All pts were divided into two age-sex-arrhythmia history duration-antiarrhythmic drugs (AAD)-matched groups. The first group consisted of 10 pts (3 women, mean age - 51,1±11,9, history of arrhythmia - 3,2±1,2 years) in whom ablation strategy consisted of PVI using LASSO technique. The second group concluded of 10 pts (3 women, mean age - 51,1±12,9, history of arrhythmia- 3,1±1,1 years) in whom ablation strategy consisted of wide-area circumferential lines application around pulmonary veins, combined to roof line and mitral isthmus RFA using three-dimensional mapping system. Mathematical phase. As the first step numeric reconstruction of the autowave process in excitable tissues of the left atrium and the simulation of AF was performed. Fitzhugh-Nagumo equation was used for simulation to enabled us to take into account the electrical inhomogeneity of the atria (pulmonary vein ostia). A special scanning method was used for calculating characteristics of autowave processes in a two-dimensional mathematical model of the atrium. As the second step simulation of circular (corresponding to LASSO approach) and linear ablation (corresponding to 3D approach) was performed. Clinical phase. There were no complications associated with RFA. 7 pts of the first group vs 4 pts of the second subgroup had early recurrences of arrhythmia. AAD free sinus rhythm incidence in the first/second groups was 80%/20% at 12 months respectively (p=0,003). Mathematical phase. While circular LASSO-like ablation pattern was used, there was no elimination of 4-waves re-entry turning around

  6. Approximation theory for boundary layer suction through individual slits

    NASA Technical Reports Server (NTRS)

    Walz, A.

    1979-01-01

    The basic concepts of influencing boundary layers are summarized, especially the prevention of flow detachment and the reduction of frictional resistance. A mathematical analysis of suction through a slit is presented with two parameters, for thickness and for shape of the boundary layer, being introduced to specify the flow's velocity profile behind the slit. An approximation of the shape parameter produces a useful formula, which can be used to determine the most favorable position of the slit. An aerodynamic example is given.

  7. Note: Compact, two-dimension translatable slit aperture.

    PubMed

    Gao, R S; Thornberry, T D; McLaughlin, R J; Fahey, D W

    2013-11-01

    A compact, light-weight, two-dimension translatable slit aperture is described. The slit dimensions are scalable, allowing for wide application. With all metal construction, the device would be suitable for high temperature degassing and vacuum compatible. Alternatively, the main structure may be printed using a 3D printer for rapid prototyping and/or lighter weight. The precision of the slit movement is 0.014 mm.

  8. Transmission resonances of metallic compound gratings with subwavelength slits.

    PubMed

    Skigin, Diana C; Depine, Ricardo A

    2005-11-18

    Transmission metallic gratings with subwavelength slits are known to produce enhanced transmitted intensity for certain resonant wavelengths. One of the mechanisms that produce these resonances is the excitation of waveguide modes inside the slits. We show that by adding slits to the period, the transmission maxima are widened and, simultaneously, this generates phase resonances that appear as sharp dips in the transmission response. These resonances are characterized by a significant enhancement of the interior field.

  9. Wave-particle dualism unraveled by Young's double slit experiment

    NASA Astrophysics Data System (ADS)

    Heuer, A.; Puhlmann, D.; Menzel, R.

    2013-10-01

    Particle and wave like properties of photons can impressively be demonstrated in Young's double slit experiment. Usually, measurements behind the slit provide information either about the path of the single photons or interference can be observed. Today the question of "which-slit" versus "interference" in the double-slit configuration is as relevant as it was in the early days of quantum mechanics. To gain deeper insight we set up an experiment using a pair of photons generated by SPDC pumped with a higher order mode (TEM01). One of the SPDC photons, the signal photon, was used to illuminate the double slit and measure the single photon interference behind it. The other photon, the idler photon, was used in a reference measurement at the position of the slit using a polarizing beam splitter. First, the signal photons were obtained at the position of the slit as a function of the position of the entangled idler photons in a coincidence measurement. From this coincidence measurement the "which-slit" information is available. In a second coincidence measurement the far field interference fringes were obtained for signal photons passing through one of the slits, only, selected by the position of the reference detector measuring the entangled idler photons. The newest results will be presented and discussed. This may provide new insights in the wave-particle dualism and thus inspire the discussion about the nature of photons.

  10. Plasmon-assisted two-slit transmission: Young's experiment revisited.

    PubMed

    Schouten, H F; Kuzmin, N; Dubois, G; Visser, T D; Gbur, G; Alkemade, P F A; Blok, H; Hooft, G W 't; Lenstra, D; Eliel, E R

    2005-02-11

    We present an experimental and theoretical study of the optical transmission of a thin metal screen perforated by two subwavelength slits, separated by many optical wavelengths. The total intensity of the far-field double-slit pattern is shown to be reduced or enhanced as a function of the wavelength of the incident light beam. This modulation is attributed to an interference phenomenon at each of the slits, instead of at the detector. The interference arises as a consequence of the excitation of surface plasmons propagating from one slit to the other.

  11. Modifications to improve entrance slit thermal stability for grasshopper monochromators

    NASA Astrophysics Data System (ADS)

    Wallace, Daniel J.; Rogers, Gregory C.; Crossley, Sherry L.

    1994-08-01

    As new monochromators are designed for high-flux storage rings, computer modeling and thermal engineering can be done to process increased heat loads and achieve mechanical stability. Several older monochromators, such as the Mark 2 and Mark 5 Grasshopper monochromators, which were designed in 1974, have thermal instabilities in their entrance slit mechanisms. The Grasshoppers operating with narrow slits experience closure of the entrance slit from thermal expansion. In extreme cases, the thermal expansion of the precision components has caused permanent mechanical damage, leaving the slit uncalibrated and/or inoperable. For the Mark 2 and Mark 5 Grasshopper monochromators at the Synchrotron Radiation Center, the original 440 stainless steel entrance slit jaws were retrofitted with an Invar (low expansion Fe, Ni alloy) slit jaw. To transfer the heat from the critical components, two flexible heat straps of Cu were attached. These changes allow safe operation with a 10 μm entrance slit width where the previous limit was 30 μm. After an initial 2 min equilibration, the slit remains stable to 10%, with 100 mA of beam current. Additional improvements in slit thermal stability are planned for a third Grasshopper.

  12. Extreme Multi-Slit Spectroscopy with GMOX

    NASA Astrophysics Data System (ADS)

    Robberto, Massimo; Heckman, Tim; Gennaro, Mario; Deustua, Susana; MacKenty, John W.; Ninkov, Zoran; Becker, George; Bianchi, Luciana; Bellini, Andrea; Calamida, Annalisa; Kalirai, Jason; Lotz, Jennifer; Sabbi, Elena; Tumlinson, Jason; Smee, Stephen; Barkhouser, Robert

    2015-08-01

    GMOX is a wide-bandwidth, moderate-resolution, multi-object spectrograph recently selected in the last Gemini Instrument Feasibility Study phase for the next facility instrument (Gen4#3). It is designed to operate at the Multi-Conjugate AO system of Gemini South (GeMs), which delivers a 90"x90" AO corrected field of view with Strehl ratio as high as 0.3 in the K-band. GMOX uses two dichroics to split the field in three modules (Blue, Red, and IR) covering the full spectral range from U to K. Each module is equipped with a Digital Micromirror Devices (DMDs) of the latest generation providing 1.1 million randomly addressable slits. Each DMD feeds a spectroscopic channel at R=4000 and a parallel imaging channel for slit alignment, monitoring and ancillary science. Exploiting the exquisit optical quality of GeMs, GMOX reaches unparalleled sensitivity and spatial resolution in crowded fields; it will represent an ideal tool to advance our understanding of star clusters and stellar populations in our Galaxy and beyond.

  13. Insight into the wetting of a graphene-mica slit pore with a monolayer of water

    NASA Astrophysics Data System (ADS)

    Lin, Hu; Schilo, Andre; Kamoka, A. Rauf; Severin, Nikolai; Sokolov, Igor M.; Rabe, Jürgen P.

    2017-05-01

    Scanning force microscopy (SFM) and Raman spectroscopy allow the unraveling of charge doping and strain effects upon wetting and dewetting of a graphene-mica slit pore with water. SFM reveals a wetting monolayer of water, slightly thinner than a single layer of graphene. The Raman spectrum of the dry pore exhibits the D' peak of graphene, which practically disappears upon wetting, and recurs when the water layer dewets the pore. Based on the 2 D - and G -peak positions, the corresponding peak intensities, and the widths, we conclude that graphene on dry mica is charge-doped and variably strained. A monolayer of water in between graphene and mica removes the doping and reduces the strain. We attribute the D' peak to direct contact of the graphene with the ionic mica surface in dry conditions, and we conclude that a complete monolayer of water wetting the slit pore decouples the graphene from the mica substrate both mechanically and electronically.

  14. Lateral positioning at the dorsal midline: Slit and Roundabout receptors guide Drosophila heart cell migration.

    PubMed

    Santiago-Martínez, Edgardo; Soplop, Nadine H; Kramer, Sunita G

    2006-08-15

    Heart morphogenesis requires the coordinated regulation of cell movements and cell-cell interactions between distinct populations of cardiac precursor cells. Little is known about the mechanisms that organize cardiac cells into this complex structure. In this study, we analyzed the role of Slit, an extracellular matrix protein and its transmembrane receptors Roundabout (Robo) and Roundabout2 (Robo2) during morphogenesis of the Drosophila heart tube, a process analogous to early heart formation in vertebrates. During heart assembly, two types of progenitor cells align into rows and coordinately migrate to the dorsal midline of the embryo, where they merge to assemble a linear heart tube. Here we show that cardiac-specific expression of Slit is required to maintain adhesion between cells within each row during dorsal migration. Moreover, differential Robo expression determines the relative distance each row is positioned from the dorsal midline. The innermost CBs express only Robo, whereas the flanking pericardial cells express both receptors. Removal of robo2 causes pericardial cells to shift toward the midline, whereas ectopic robo2 in CBs drives them laterally, resulting in an unfused heart tube. We propose a model in which Slit has a dual role during assembly of the linear heart tube, functioning to regulate both cell positioning and adhesive interactions between migrating cardiac precursor cells.

  15. Slit and robo expression in the developing mouse lung.

    PubMed

    Greenberg, James M; Thompson, Felisa Y; Brooks, Sherry K; Shannon, John M; Akeson, Ann L

    2004-06-01

    Mammalian lung development is mediated through complex interactions between foregut endoderm and surrounding mesenchyme. As airway branching progresses, the mesenchyme undergoes dramatic remodeling and differentiation. Little is understood about the mechanisms that direct mesenchymal organization during lung development. A screen for candidate genes mediating this process identified Slit, a ligand for the Roundabout (Robo) receptor previously associated with guidance of axonal projections during central nervous system development. Here, we demonstrate by in situ hybridization that two Slit genes (Slit-2 and Slit-3) and two Robo genes (Robo-1 and Robo-2) are expressed in fetal lung mesenchyme. Slit-2 and Robo-1 expression is present throughout mesenchyme at midgestation and is not detectable by newborn day 1. Slit-3 and Robo-2 expression is restricted to specific, complementary subsets of mesenchyme. Robo-2 is expressed in mesenchymal cells immediately adjacent to large airways, whereas Slit-3 expression predominates in mesenchyme remote from airway epithelium. The temporal and spatial distribution of Slit and Robo mRNAs indicate that these genes may direct the functional organization and differentiation of fetal lung mesenchyme.

  16. High-definition slit-lamp video camera system.

    PubMed

    Yamamoto, Satoru; Manabe, Noriyoshi; Yamamoto, Kenji

    2010-01-01

    Using a high-definition video camera for slit-lamp examination is now possible with the assistance of an adaptor. The authors describe the easy manipulation, convenience of use, and performance of a high-definition slit-lamp video camera system and provide images of eyes that were obtained using the system.

  17. Single-Slit Diffraction and the Uncertainty Principle

    ERIC Educational Resources Information Center

    Rioux, Frank

    2005-01-01

    A theoretical analysis of single-slit diffraction based on the Fourier transform between coordinate and momentum space is presented. The transform between position and momentum is used to illuminate the intimate relationship between single-slit diffraction and uncertainty principle.

  18. Single-Slit Diffraction and the Uncertainty Principle

    ERIC Educational Resources Information Center

    Rioux, Frank

    2005-01-01

    A theoretical analysis of single-slit diffraction based on the Fourier transform between coordinate and momentum space is presented. The transform between position and momentum is used to illuminate the intimate relationship between single-slit diffraction and uncertainty principle.

  19. Continuous-flow biodiesel production using slit-channel reactors.

    PubMed

    Kalu, Egwu Eric; Chen, Ken S; Gedris, Tom

    2011-03-01

    Slit-channel reactors are reactors whose active surface areas are orders of magnitude higher than those of micro-reactors but have low fabrication costs relative to micro-reactors. We successfully produced biodiesel with different degrees of conversion using homogeneous catalyst in the slit-channel reactor. The reactor performance shows that percent conversion of soybean oil to biodiesel increases with channel depth, as expected, due to more efficient mixing. Shallow slit-channels require short average residence times for complete product conversion. Present results show that the slit-channel reactor provides an improved performance over traditional batch reactors using homogeneous sodium alkoxide catalyst. It is aimed to couple the reactors with solid catalysts in converting soybean oil to biodiesel and implementation method is suggested. The cost advantages resulting from the ease of fabrication of slit-channel reactors over micro-reactors and how these factors relate to the oil conversion efficiency to biodiesel are briefly noted and discussed.

  20. The double slit experiment and the time reversed fire alarm

    NASA Astrophysics Data System (ADS)

    Halabi, Tarek

    2011-03-01

    When both slits of the double slit experiment are open, closing one paradoxically increases the detection rate at some points on the detection screen. Feynman famously warned that temptation to "understand" such a puzzling feature only draws us into blind alleys. Nevertheless, we gain insight into this feature by drawing an analogy between the double slit experiment and a time reversed fire alarm. Much as closing the slit increases probability of a future detection, ruling out fire drill scenarios, having heard the fire alarm, increases probability of a past fire (using Bayesian inference). Classically, Bayesian inference is associated with computing probabilities of past events. We therefore identify this feature of the double slit experiment with a time reversed thermodynamic arrow. We believe that much of the enigma of quantum mechanics is simply due to some variation of time's arrow.

  1. Mobilizing slit lamp to the field: A new affordable solution.

    PubMed

    Farooqui, Javed Hussain; Jorgenson, Richard; Gomaa, Ahmed

    2015-11-01

    We are describing a simple and affordable design to pack and carry the slit lamp to the field. Orbis staff working on the Flying Eye Hospital (FEH) developed this design to facilitate mobilization of the slit lamp to the field during various FEH programs. The solution involves using a big toolbox, a central plywood apparatus, and foam. These supplies were cut to measure and used to support the slit lamp after being fitted snuggly in the box. This design allows easy and safe mobilization of the slit lamp to remote places. It was developed with the efficient use of space in mind and it can be easily reproduced in developing countries using same or similar supplies. Mobilizing slit lamp will be of great help for staff and institutes doing regular outreach clinical work.

  2. 6 Mcps photon-counting X-ray computed tomography system using a 25 mm/s-scan linear LSO-MPPC detector and its application to gadolinium imaging

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Oda, Yasuyuki; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sugimura, Shigeaki; Endo, Haruyuki; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2011-12-01

    6 Mcps photon counting was carried out using a detector consisting of a 1.0 mm-thick LSO [Lu 2(SiO 4)O] single-crystal scintillator and an MPPC (multipixel photon counter) module in an X-ray computed tomography (CT) system. The maximum count rate was 6 Mcps (mega counts per second) at a tube voltage of 100 kV and a tube current of 0.91 mA. Next, a photon-counting X-ray CT system consists of an X-ray generator, a turntable, a scan stage, a two-stage controller, the LSO-MPPC detector, a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan with a scan velocity of 25 mm/s. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The exposure time for obtaining a tomogram was 600 s at a scan step of 0.5 mm and a rotation step of 1.0°, and photon-counting CT was accomplished using gadolinium-based contrast media.

  3. Stowage and Deployment of Slit Tube Booms

    NASA Technical Reports Server (NTRS)

    Adams, Larry (Inventor); Turse, Dana (Inventor); Richardson, Doug (Inventor)

    2016-01-01

    A system comprising a boom having a first end, a longitudinal length, and a slit that extends along the longitudinal length of the boom; a drum having an elliptic cross section and a longitudinal length; an attachment mechanism coupled with the first end of the boom and the drum such that the boom and the drum are substantially perpendicular relative to one another; an inner shaft having a longitudinal length, the inner shaft disposed within the drum, the longitudinal length of the inner shaft is aligned substantially parallel with the longitudinal length of the drum, the inner shaft at least partially rotatable relative to the drum, and the inner shaft is at least partially rotatable with the drum; and at least two cords coupled with the inner shaft and portions of the boom near the first end of the boom.

  4. Slit Spectra of Second Byurakan Survey Galaxies

    NASA Astrophysics Data System (ADS)

    Osterbrock, D. E.; Martel, A.

    1993-12-01

    Slit spectra have been obtained at Lick Observatory of 18 Seyfert galaxy candidates from the Second Byurakan Spectral Sky Survey (SBS). The great majority of them turned out to be Seyfert galaxies. The classifications and redshifts of all the galaxies are reported. Measurements of the intensity ratios of the emission lines used in classifying the galaxies are tabulated and plotted on diagnostic diagrams. The spectra of seven of the galaxies are described in detail. In general, our classification and redshift measurements are in very good accord with those of Lipovetsky, Stepanian, and their collaborators at the Special Astrophysical Observatory, showing that their results can be used in conjunction with the Lick results with little if any systematic difference between the two data sets. The importance of the SBS as a source of new Seyferts bridging the gap between low-redshift Seyfert galaxies and higher-luminosity QSOs is also emphasized.

  5. Flow of bovine collagen in rectangular slit

    NASA Astrophysics Data System (ADS)

    Skočilas, Jan; Žitný, Rudolf; Štancl, Jaromír; Solnař, Stanislav; Landfeld, Aleš; Houška, Milan

    2017-05-01

    This contribution deals with the investigation of the bovine collagen flow in the rectangular slit. The slightly compressible collagen liquid (9.5% mass fraction of native bovine collagen in water) was extruded by capillary rheometer of given geometry. A piston pushed the collagen sample from a container to the rectangular capillary. The extrusion rheometer is equipped by pressure sensors mounted at wall of capillary and manually adjusted hydraulic drive enables continuous variation of the piston velocity. The pressure profiles are measured in five places along the capillary simultaneously with increasing shear rate within the range from 1500 to 5000 s-1. It is possible to identify non-elastic shear flow characteristic and the compressibility of collagen matter.

  6. White beam slits and pink beam slits for the hard x-ray nanoprobe beamline at the Advanced Photon Source.

    SciTech Connect

    Benson, C.; Jaski, Y.; Maser, J.; Powers, T.; Schmidt, O.; Rossi, E.

    2007-01-01

    A new type of slit has been designed for use in the hard x-ray nanoprobe beamline at the Advanced Photon Source (APS). The design incorporates monolithic GlidCop slit bodies mounted to commercially available x-y drive systems. Long, tapered apertures with adjacent water-cooling channels intercept the x-ray beam, removing the high heat load produced by two collinear APS undulators. The apertures are L-shaped and provide both horizontal and vertical slits. The beam-defining edges, positioned at the end of the tapered surfaces, consist of two sets of tungsten blades. These blades produce an exit beam with sharp corners and assure a clean cut-off for the white beam edges. The slit assembly is designed to allow overlap of the slit edges to stop the beam. The white beam slit design accommodates 3100 W of total power with a peak power density of 763 W/mm2. The pink beam slit design accommodates 400 W of total power with a peak power density of 180 W/mm2. Detailed thermal analyses were performed to verify the slits accuracy under full beam loading. The new concept allows beamline operations to 180 mA with a simplified design approach.

  7. White Beam Slits and Pink Beam Slits for the Hard X-ray Nanoprobe Beamline at the Advanced Photon Source

    SciTech Connect

    Benson, C.; Jaski, Y.; Powers, T.; Schmidt, O.; Rossi, E.; Maser, J.

    2007-01-19

    A new type of slit has been designed for use in the hard x-ray nanoprobe beamline at the Advanced Photon Source (APS). The design incorporates monolithic GlidCop slit bodies mounted to commercially available x-y drive systems. Long, tapered apertures with adjacent water-cooling channels intercept the x-ray beam, removing the high heat load produced by two collinear APS undulators. The apertures are L-shaped and provide both horizontal and vertical slits. The beam-defining edges, positioned at the end of the tapered surfaces, consist of two sets of tungsten blades. These blades produce an exit beam with sharp corners and assure a clean cut-off for the white beam edges. The slit assembly is designed to allow overlap of the slit edges to stop the beam.The white beam slit design accommodates 3100 W of total power with a peak power density of 763 W/mm2. The pink beam slit design accommodates 400 W of total power with a peak power density of 180 W/mm2. Detailed thermal analyses were performed to verify the slits' accuracy under full beam loading. The new concept allows beamline operations to 180 mA with a simplified design approach.

  8. Dynamic scan control in STEM: Spiral scans

    DOE PAGES

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

    2016-06-13

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

  9. Bandgaps characteristics of the periodical slit metal tubes with backstraps

    NASA Astrophysics Data System (ADS)

    Bao, Kai; Chen, Tianning; Wang, Xiaopeng; Song, Ailing; Wan, Lele

    2017-06-01

    In this paper, a new two-dimensional (2D) phononic crystal structure composed of periodic slit metal tubes, in which the unit cell consists of straight or curved backstraps, is proposed, and the propagation characteristics of acoustic waves in this structure are theoretically investigated. Using the finite-element method, we calculate the dispersion relations and transmission coefficients of this structure. The results show that, in contrast to the only slit metal tubes, the periodic slit metal tubes with straight or curved backstraps are proved to display band gaps (BGs) at much lower frequency range. Meanwhile, the effect of the slit width of the backstraps on the BGs is investigated. The results show that the positions and widths of the BGs can be effectively modulated by the backstraps without changing the mass density or lattice constant of the material. The lowest frequency falls by about 200 Hz. Moreover, we investigated how the BGs are affected by the location parameter of the backstraps, finding that the acoustic BGs are sensitive to the location parameter of the backstraps. Numerical results show that BGs are significantly dependent upon the slit width and location parameters of the backstraps. The BGs are optimized because, the effect of the Helmholtz resonators of the slit tube is strengthened and changed when the location and slit width of the backstraps change. These results provide a good reference for optimizing BGs, generating filters and designing devices.

  10. Dielectric response of polar liquids in narrow slit pores.

    PubMed

    Froltsov, Vladimir A; Klapp, Sabine H L

    2007-03-21

    Based on molecular dynamics (MD) simulations and a simple (Stockmayer) model we investigate the static and dynamic dielectric response of polar liquids confined to narrow slit pores. The MD simulations are used to calculate the time-dependent polarization fluctuations along directions parallel and perpendicular to the walls, from which the components of the frequency-dependent dielectric tensor can be derived via linear response theory. Our numerical results reveal that the system's response is strongly anisotropic. The parallel dielectric function, epsilonparallel(omega), has Debye-like character very similar to the corresponding isotropic bulk function, epsilonbulk(omega), at the same chemical potential. Indeed, the main confinement effect on epsilonparallel(omega) consists in a shift toward smaller values relative to the bulk function. On the other hand, in the perpendicular direction we observe a characteristic peak in the absorption part of the dielectric function, epsilonperpendicular(omega). This peak is absent in the bulk system and reflects strongly pronounced, damped oscillations in the polarization fluctuations normal to the walls. We discuss two possible origins of the oscillations (and the resulting absorption peak), that is collective oscillations of dipoles in clusters formed parallel to the walls, and the existence of a "dipolaron mode" previously observed in MD simulations of bulk polar fluids.

  11. Slit-lamp photography and videography with high magnifications

    PubMed Central

    Yuan, Jin; Jiang, Hong; Mao, Xinjie; Ke, Bilian; Yan, Wentao; Liu, Che; Cintrón-Colón, Hector R; Perez, Victor L; Wang, Jianhua

    2015-01-01

    Purpose To demonstrate the use of the slit-lamp photography and videography with extremely high magnifications for visualizing structures of the anterior segment of the eye. Methods A Canon 60D digital camera with Movie Crop Function was adapted into a Nikon FS-2 slit-lamp to capture still images and video clips of the structures of the anterior segment of the eye. Images obtained using the slit-lamp were tested for spatial resolution. The cornea of human eyes was imaged with the slit-lamp and the structures were compared with the pictures captured using the ultra-high resolution optical coherence tomography (UHR-OCT). The central thickness of the corneal epithelium and total cornea was obtained using the slit-lamp and the results were compared with the thickness obtained using UHR-OCT. Results High-quality ocular images and higher spatial resolutions were obtained by using the slit-lamp with extremely high magnifications and Movie Crop Function, rather than the traditional slit-lamp. The structures and characteristics of the cornea, such as the normal epithelium, abnormal epithelium of corneal intraepithelial neoplasia, LASIK interface, and contact lenses, were clearly visualized using this device. These features were confirmed by comparing the obtained images with those acquired using UHR-OCT. Moreover, the tear film debris on the ocular surface and the corneal nerve in the anterior corneal stroma were also visualized. The thicknesses of the corneal epithelium and total cornea were similar to that measured using UHR-OCT (P < 0.05). Conclusions We demonstrated that the slit-lamp photography and videography with extremely high magnifications allows better visualization of the anterior segment structures of the eye, especially of the epithelium, when compared with the traditional slit-lamp. PMID:26020484

  12. A two-photon double-slit experiment

    NASA Astrophysics Data System (ADS)

    Menzel, R.; Heuer, A.; Puhlmann, D.; Dechoum, K.; Hillery, M.; Spähn, M. J. A.; Schleich, W. P.

    2013-01-01

    We employ a photon pair created by spontaneous parametric down conversion (SPDC) where the pump laser is in the TEM01 mode to perform a Young's double-slit experiment. The signal photon illuminates the two slits and displays interference fringes in the far-field while the idler photon measured in the near-field in coincidence with the signal photon provides us with 'which-slit' information. We explain the results of these experiments with the help of an analytical expression for the second-order correlation function derived from an elementary model of SPDC. Our experiment emphasizes the crucial role of the mode function in the quantum theory of radiation.

  13. Three Slit Experiments and the Structure of Quantum Theory

    NASA Astrophysics Data System (ADS)

    Ududec, Cozmin; Barnum, Howard; Emerson, Joseph

    2011-03-01

    In spite of the interference manifested in the double-slit experiment, quantum theory predicts that a measure of interference defined by Sorkin and involving various outcome probabilities from an experiment with three slits, is identically zero. We adapt Sorkin's measure into a general operational probabilistic framework for physical theories, and then study its relationship to the structure of quantum theory. In particular, we characterize the class of probabilistic theories for which the interference measure is zero as ones in which it is possible to fully determine the state of a system via specific sets of `two-slit' experiments.

  14. Optical forces on resonant metallic cylinders near supertransmitting slits

    NASA Astrophysics Data System (ADS)

    Valero, Francisco Javier Valdivia; Vesperinas, Manuel Nieto

    2012-09-01

    We study the optical forces on 2D metallic particles, i. e. infinite cylinders, in or out their Mie resonances, near a subwavelength slit in extraordinary transmission regime, illuminated by a Gaussian beam. We show that the presence of the slit enhances by two orders of magnitude the transversal forces of optical tweezers from a beam alone. We demonstrate an enhancement forces, also of binding nature, at plasmon resonance wavelengths on metallic nanocylinders. The role of both scattering and gradient forces are addressed, for the particles at either the exit or entrance of the slit, regarding the bonding or antibonding nature of the overall force on them.

  15. Nanotribological investigations of NCD coatings covering metal slitting saws

    NASA Astrophysics Data System (ADS)

    Golabczak, A.; Niedzielski, Piotr; Mitura, Stanislaw; Zak, J.

    1997-06-01

    In the paper an assessment of the usefulness of a method for the formation of a hard carbon coating on the working surface of metal slitting saws has been presented. Metal slitting saws were used to cut off the tips of non-ferrous metals in printed-circuit boards. The results o the authors' own investigations concerning the assessment of life of metal slitting saws with modified geometry of the cutting edge and a hard carbon coating have been presented. Conclusions on the practicability of the RF PCVD method used have been formulated.

  16. Amontillado is required for Drosophila Slit processing and for tendon-mediated muscle patterning

    PubMed Central

    Ordan, Elly

    2016-01-01

    ABSTRACT Slit cleavage into N-terminal and C-terminal polypeptides is essential for restricting the range of Slit activity. Although the Slit cleavage site has been characterized previously and is evolutionally conserved, the identity of the protease that cleaves Slit remains elusive. Our previous analysis indicated that Slit cleavage is essential to immobilize the active Slit-N at the tendon cell surfaces, mediating the arrest of muscle elongation. In an attempt to identify the protease required for Slit cleavage we performed an RNAi-based assay in the ectoderm and followed the process of elongation of the lateral transverse muscles toward tendon cells. The screen led to the identification of the Drosophila homolog of pheromone convertase 2 (PC2), Amontillado (Amon), as an essential protease for Slit cleavage. Further analysis indicated that Slit mobility on SDS polyacrylamide gel electrophoresis (SDS-PAGE) is slightly up-shifted in amon mutants, and its conventional cleavage into the Slit-N and Slit-C polypeptides is attenuated. Consistent with the requirement for amon to promote Slit cleavage and membrane immobilization of Slit-N, the muscle phenotype of amon mutant embryos was rescued by co-expressing a membrane-bound form of full-length Slit lacking the cleavage site and knocked into the slit locus. The identification of a novel protease component essential for Slit processing may represent an additional regulatory step in the Slit signaling pathway. PMID:27628033

  17. Semiclassical simulation of the double-slit experiments with single photons

    NASA Astrophysics Data System (ADS)

    Rashkovskiy, Sergey A.

    2015-12-01

    Many quantum phenomena, traditionally described by quantum electrodynamics, can be calculated within the framework of so-called semiclassical theory, in which atoms are described by the wave equations of quantum mechanics (Schrödinger, Dirac, etc.), while light is described by classical electrodynamics without quantization of the radiation. These phenomena include the photoelectric effect, the Compton effect, the Lamb shift, radiative effects, spontaneous emission, the Hanbury Brown and Twiss effect, etc. In this paper, I show that the double-slit experiment can also be calculated in detail in terms of semiclassical theory if we take into account the discrete (atomic) structure of matter. I show that the results of a semiclassical simulation of the "linear" double-slit experiment coincide with predictions of wave theory only for low-intensity light and for short exposure time, while stricter dependences exist for long-term exposure. The semiclassical theory is used for calculation of the "nonlinear" double-slit experiment with an intense laser beam in which multiphoton and tunnel excitation of atoms on a photographic plate occurs. The Born rule for light is derived from the semiclassical theory.

  18. Comparison of a remote operating slit-lamp microscope system with a conventional slit-lamp microscope system for examination of trabeculectomy eyes.

    PubMed

    Kashiwagi, Kenji; Tanabe, Naohiko; Go, Kentaro; Imasawa, Mitsuhiro; Mabuchi, Fumihiko; Chiba, Tetsuya; Sugiyama, Atsushi; Abe, Keitetsu

    2013-01-01

    To compare 2-dimensional (2D) photo imaging with slit-lamp photo imaging for examination of trabeculectomy eyes, and to compare the accuracy and consistency of examination of trabeculectomy eyes with a remote operating slit-lamp microscope system (referred to as "remote slit lamp" hereafter) and a conventional slit-lamp microscope system (referred to as "slit lamp" hereafter). Thirty-five eyes of 35 patients having a history of trabeculectomy were enrolled in the study that compared 2D photo imaging with slit-lamp photo imaging for the evaluation of trabeculectomy eyes. Five ophthalmologists evaluated the 2D images and the slit-lamp images independently with masking of patient information. Evaluation scores were compared with those provided by a glaucoma specialist using the slit lamp as standard. Fifteen eyes from 15 patients having a history of trabeculectomy were enrolled in the study that investigated the accuracy and consistency of examination of trabeculectomy eyes with a remote slit lamp and a slit lamp. Central anterior chamber depth, bleb height, and bleb extent evaluated by the slit-lamp photo imaging showed significantly higher consistency with the standard than those evaluated by 2D photo imaging (P<0.05). The remote slit lamp showed good consistency of all the evaluated parameters with the slit lamp and the κ scores of all the evaluated parameters were higher than 0.8. The completion time for evaluation with the remote slit lamp and the slit lamp were 247.3±153.5 and 123.5±53.7 seconds, respectively (P<0.001). Slit-lamp photo imaging is a superior method for examination of trabeculectomy eyes compared with 2D photo imaging. The remote slit-lamp system shows similar potential to the slit-lamp system for the evaluation of trabeculectomy eyes, although the evaluation time is much longer.

  19. Corneal astigmatism measuring module for slit lamps

    NASA Astrophysics Data System (ADS)

    Ventura, L.; Riul, C.; Sousa, S. J. F.; DeGroote, J. G. S.; Rosa Filho, A. B.; Oliveira, G. C. D.

    2006-06-01

    We have developed an automatic keratometer module for slit lamps that provides automatic measurements of the radii of the corneal curvature. The system projects 72 light spots displayed in a precise circle at the examined cornea. The displacement and deformation of the reflected image of these light spots are analysed providing the keratometry. Measurements in the range of 26.8-75 D can be obtained and a self-calibration system has been specially designed in order to keep the system calibrated. Infrared LEDs indicate automatically which eye is being examined. Volunteer patients (492) have been submitted to the system and the results show that our system has a high correlation factor with the commercially available manual keratometers and the keratometry measurements from a topographer. Our developed system is 95% in agreement with the corneal topographer (Humphrey—Atlas 995 CZM) and the manual keratometer (Topcon OM-4). The system's nominal precision is 0.05 mm for the radii of curvature and 1° for the associated axis. This research has been supported by Fundação de Apoio à Pesquisa do Estado de São Paulo (FAPESP).

  20. Springback Prediction on Slit-Ring Test

    SciTech Connect

    Chen Xiaoming; Shi, Ming F.; Ren Feng; Xia, Z. Cedric

    2005-08-05

    Advanced high strength steels (AHSS) are increasingly being used in the automotive industry to reduce vehicle weight while improving vehicle crash performance. One of the concerns in manufacturing is springback control after stamping. Although computer simulation technologies have been successfully applied to predict stamping formability, they still face major challenges in springback prediction, particularly for AHSS. Springback analysis is very complicated and involves large deformation problems in the forming stage and mechanical multiplying effect during the elastic recovery after releasing a part from the die. Therefore, the predictions are very sensitive to the simulation parameters used. It is very critical in springback simulation to choose an appropriate material model, element formulation and contact algorithm. In this study, a springback benchmark test, the slit ring cup, is used in the springback simulation with commercially available finite element analysis (FEA) software, LS-DYNA. The sensitivity of seven simulation variables on springback predictions was investigated, and a set of parameters with stable simulation results was identified. Final simulations using the selected set of parameters were conducted on six different materials including two AHSS steels, two conventional high strength steels, one mild steel and an aluminum alloy. The simulation results are compared with experimental measurements for all six materials and a favorable result is achieved. Simulation errors as compared against test results falls within 10%.

  1. Freezing of charged colloids in slit pores.

    PubMed

    Grandner, Stefan; Klapp, Sabine H L

    2008-12-28

    Using Monte Carlo simulations in the grand canonical and isobaric ensembles we investigate freezing phenomena in a charged colloidal suspension confined to narrow slit pores. Our model involves only the macroions which interact via a Derjaguin-Landau-Verwey-Overbeek (DLVO) potential supplemented by a soft-sphere potential. We focus on DLVO parameters typical for moderately charged silica particles (with charges Z approximately 35) in solvents of low ionic strengths. The corresponding DLVO interactions are too weak to drive a (bulk) freezing transition. Nevertheless, for sufficiently small surface separations L(z) the confined systems display not only layering but also significant in-plane crystalline order at chemical potentials where the bulk system is a globally stable fluid (capillary freezing). At confinement conditions related to two-layer systems the observed in-plane structures are consistent with those detected in ground state calculations for perfect Yukawa bilayers [R. Messina and H. Lowen, Phys. Rev. Lett. 91, 146101 (2003)]. Here we additionally observe (at fixed L(z)) a compression-induced first-order phase transition from a two-layer to a three-layer system with different in-plane structure, in agreement with previous findings for pure hard spheres.

  2. Spectral anomalies in Young's double-slit interference experiment.

    PubMed

    Pu, Jixiong; Cai, Chao; Nemoto, Shojiro

    2004-10-18

    We report a phenomenon of spectral anomalies in the interference field of Young's double-slit interference experiment. The potential applications of the spectral anomalies in the information encoding and information transmission in free space are also considered.

  3. Endocytic Trafficking at the Mature Podocyte Slit Diaphragm

    PubMed Central

    Swiatecka-Urban, Agnieszka

    2017-01-01

    Endocytic trafficking couples cell signaling with the cytoskeletal dynamics by organizing a crosstalk between protein networks in different subcellular compartments. Proteins residing in the plasma membrane are internalized and transported as cargo in endocytic vesicles (i.e., endocytosis). Subsequently, cargo proteins can be delivered to lysosomes for degradation or recycled back to the plasma membrane. The slit diaphragm is a modified tight junction connecting foot processes of the glomerular epithelial cells, podocytes. Signaling at the slit diaphragm plays a critical role in the kidney while its dysfunction leads to glomerular protein loss (proteinuria), manifesting as nephrotic syndrome, a rare condition with an estimated incidence of 2–4 new cases per 100,000 each year. Relatively little is known about the role of endocytic trafficking in podocyte signaling and maintenance of the slit diaphragm integrity. This review will focus on the role of endocytic trafficking at the mature podocyte slit diaphragm. PMID:28286744

  4. Optical design of MWIR imaging spectrometer with a cold slit

    NASA Astrophysics Data System (ADS)

    Zhou, Shiyao; Wang, Yueming; Qian, Liqun; Yuan, Liyin; Wang, Jianyu

    2016-05-01

    MWIR imaging spectrometer is promising in detecting spectral signature of high temperature object such as jet steam, guided missile and explosive gas. This paper introduces an optical design of a MWIR imaging spectrometer with a cold slit sharply reducing the stray radiation from exterior environment and interior structure. The spectrometer is composed of a slit, a spherical prism as disperser, two concentric spheres and a correction lens. It has a real entrance pupil to match the objective and for setting the infrared cold shield near the slit and a real exit pupil to match the cold shield of the focal plane array (FPA). There are two cooled parts, one includes the aperture stop and slit, and the other is the exit pupil and the FPA with two specially positioned cooled shields. A detailed stray radiation analysis is represented which demonstrates the outstanding effect of this system in background radiation restraint.

  5. A Computational and Experimental Study of Slit Resonators

    NASA Technical Reports Server (NTRS)

    Tam, C. K. W.; Ju, H.; Jones, M. G.; Watson, W. R.; Parrott, T. L.

    2003-01-01

    Computational and experimental studies are carried out to offer validation of the results obtained from direct numerical simulation (DNS) of the flow and acoustic fields of slit resonators. The test cases include slits with 90-degree corners and slits with 45-degree bevel angle housed inside an acoustic impedance tube. Three slit widths are used. Six frequencies from 0.5 to 3.0 kHz are chosen. Good agreement is found between computed and measured reflection factors. In addition, incident sound waves having white noise spectrum and a prescribed pseudo-random noise spectrum are used in subsequent series of tests. The computed broadband results are again found to agree well with experimental data. It is believed the present results provide strong support that DNS can eventually be a useful and accurate prediction tool for liner aeroacoustics. The usage of DNS as a design tool is discussed and illustrated by a simple example.

  6. Double Slit Diffraction Experiments with Surface Plasmon Polaritons

    NASA Astrophysics Data System (ADS)

    Alam, Kamrul; Grave-de-Peralta, Luis

    2012-10-01

    Young's double slit experiment is the most famous interference experiment. Two parallel waveguides were used for producing interference patterns with Surface Plasmon Polaritons (SPP), which are equivalent to a double slit diffraction experiment. SPP interference was studied using SPP tomography. A series of experiments were done changing the separation and width of the waveguides. There was a good correspondence between observed and simulated interference patterns.

  7. Young's double-slit experiment in photonic crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Koschny, Thomas; Soukoulis, C. M.

    2012-10-01

    We present an experimental and numerical study of the transmission of a photonic crystal perforated by two subwavelength slits, separated by two wavelengths. The experimental near-field image of the double-slit design of the photonic crystal shows an interference pattern, which is analogous to Young's experiment. This interference arises as a consequence of the excitation of surface states of the photonic crystals and agrees very well with the simulations.

  8. Young's double-slit experiment in photonic crystals

    SciTech Connect

    Zhang, Lei; Koschny, Thomas; Soukoulis, Costas M.

    2012-10-01

    We present an experimental and numerical study of the transmission of a photonic crystal perforated by two sub-wavelength slits, separated by two wavelengths.The experimental near-field image of the double-slit design of the photonic crystal shows an interference pattern, which is analogous to Young’s experiment. This interference arises as a consequence of the excitation of surface states of the photonic crystals and agrees very well with the simulations.

  9. Imaging Spectrometer Designs Utilizing Immersed Gratings With Accessible Entrance Slit

    DOEpatents

    Chrisp, Michael P.; Lerner, Scott A.

    2006-03-21

    A compact imaging spectrometer comprises an entrance slit, a catadioptric lens with a mirrored surface, a grating, and a detector array. The entrance slit directs light to the mirrored surface of the catadioptric lens; the mirrored surface reflects the light back through the lens to the grating. The grating receives the light from the catadioptric lens and diffracts the light to the lens away from the mirrored surface. The lens transmits the light and focuses it onto the detector array.

  10. Gouy phase and visibility in the double-slit experiment

    SciTech Connect

    Ferreira, C.J.S.; Marinho, L.S.; Brazil, T.B.; Cabral, L.A.; Oliveira Jr, J.G.G. de; Sampaio, M.D.R.; Paz, I.G. da

    2015-11-15

    We study a matter wave double-slit experiment with unequal aperture widths in order to evaluate the effect of the Gouy phase on the visibility/predictability. While the predictability changes as one increases the width of one of the slits, the visibility receives a contribution from the Gouy phase at a specific point in the detection screen. Consequently such apparatus constitutes a simple device for measuring the Gouy phase of matter waves. We illustrate it numerically for neutrons.

  11. Boundary-Layer Effects on Acoustic Transmission Through Narrow Slit Cavities.

    PubMed

    Ward, G P; Lovelock, R K; Murray, A R J; Hibbins, A P; Sambles, J R; Smith, J D

    2015-07-24

    We explore the slit-width dependence of the resonant transmission of sound in air through both a slit array formed of aluminum slats and a single open-ended slit cavity in an aluminum plate. Our experimental results accord well with Lord Rayleigh's theory concerning how thin viscous and thermal boundary layers at a slit's walls affect the acoustic wave across the whole slit cavity. By measuring accurately the frequencies of the Fabry-Perot-like cavity resonances, we find a significant 5% reduction in the effective speed of sound through the slits when an individual viscous boundary layer occupies only 5% of the total slit width. Importantly, this effect is true for any airborne slit cavity, with the reduction being achieved despite the slit width being on a far larger scale than an individual boundary layer's thickness. This work demonstrates that the recent prevalent loss-free treatment of narrow slit cavities within acoustic metamaterials is unrealistic.

  12. Boundary-Layer Effects on Acoustic Transmission Through Narrow Slit Cavities

    NASA Astrophysics Data System (ADS)

    Ward, G. P.; Lovelock, R. K.; Murray, A. R. J.; Hibbins, A. P.; Sambles, J. R.; Smith, J. D.

    2015-07-01

    We explore the slit-width dependence of the resonant transmission of sound in air through both a slit array formed of aluminum slats and a single open-ended slit cavity in an aluminum plate. Our experimental results accord well with Lord Rayleigh's theory concerning how thin viscous and thermal boundary layers at a slit's walls affect the acoustic wave across the whole slit cavity. By measuring accurately the frequencies of the Fabry-Perot-like cavity resonances, we find a significant 5% reduction in the effective speed of sound through the slits when an individual viscous boundary layer occupies only 5% of the total slit width. Importantly, this effect is true for any airborne slit cavity, with the reduction being achieved despite the slit width being on a far larger scale than an individual boundary layer's thickness. This work demonstrates that the recent prevalent loss-free treatment of narrow slit cavities within acoustic metamaterials is unrealistic.

  13. Steerable-filter based quantification of axonal populations at the developing optic chiasm reveal significant defects in Slit2−/− as well as Slit1−/−Slit2−/− embryos

    PubMed Central

    2013-01-01

    Background Previous studies have suggested that the axon guidance proteins Slit1 and Slit2 co-operate to establish the optic chiasm in its correct position at the ventral diencephalic midline. This is based on the observation that, although both Slit1 and Slit2 are expressed around the ventral midline, mice defective in either gene alone exhibit few or no axon guidance defects at the optic chiasm whereas embryos lacking both Slit1 and Slit2 develop a large additional chiasm anterior to the chiasm’s normal position. Here we used steerable-filters to quantify key properties of the population of axons at the chiasm in wild-type, Slit1−/−, Slit2−/− and Slit1−/−Slit2−/− embryos. Results We applied the steerable-filter algorithm successfully to images of embryonic retinal axons labelled from a single eye shortly after they have crossed the midline. We combined data from multiple embryos of the same genotype and made statistical comparisons of axonal distributions, orientations and curvatures between genotype groups. We compared data from the analysis of axons with data on the expression of Slit1 and Slit2. The results showed a misorientation and a corresponding anterior shift in the position of many axons at the chiasm of both Slit2−/− and Slit1−/−Slit2−/− mutants. There were very few axon defects at the chiasm of Slit1−/− mutants. Conclusions We found defects of the chiasms of Slit1−/−Slit2−/− and Slit1−/− mutants similar to those reported previously. In addition, we discovered previously unreported defects resulting from loss of Slit2 alone. This indicates the value of a quantitative approach to complex pathway analysis and shows that Slit2 can act alone to control aspects of retinal axon routing across the ventral diencephalic midline. PMID:23320558

  14. Use of a high-frequency linear transducer and MTI filtered color flow mapping in the assessment of fetal heart anatomy at the routine 11 to 13 + 6-week scan: a randomized trial.

    PubMed

    Votino, C; Kacem, Y; Dobrescu, O; Dessy, H; Cos, T; Foulon, W; Jani, J

    2012-02-01

    To prospectively assess the contribution of a high-frequency linear transducer and of moving target indicator (MTI) filtered color flow mapping in the visualization of cardiac fetal anatomy at the routine 11 to 13 + 6-week scan. This was a cross-sectional prospective study, including 300 singleton fetuses at 11 to 13 + 6 weeks' gestation. Patients were randomized into four groups and a detailed fetal cardiac examination was conducted transabdominally using either a conventional curvilinear transducer, a conventional curvilinear transducer and MTI filtered color flow mapping, a high-frequency linear transducer or a high-frequency linear transducer and MTI filtered color flow mapping. Regression analysis was used to investigate the effect on the ability to visualize different cardiac structures of the following parameters: gestational age at ultrasound examination; fetal crown-rump length (CRL); maternal body mass index (BMI); transducer-heart distance; the technique used at ultrasound; and the position of the placenta. The four-chamber view was visualized in 89.0% of fetuses and regression analysis showed this rate was correlated with CRL and the use of MTI filtered color flow mapping during ultrasonography, and inversely correlated with BMI and transducer-heart distance. Use of a conventional curvilinear transducer and MTI filtered color flow mapping allowed visualization of the four-chamber view in 97.3% of fetuses, while this was only possible in 84.0% of fetuses using a high-frequency linear transducer. The left and right outflow tracts were visualized in 62.3 and 57.7% of fetuses, respectively. Regression analysis showed that the ability to visualize the left or the right outflow tract was correlated with the use of MTI filtered color flow mapping during scanning and was inversely correlated with transducer-heart distance. The use of a conventional curvilinear transducer and MTI filtered color flow mapping allowed visualization of the left and right outflow

  15. Telescopic measurements of backscattered radiation from secondary collimator jaws to a beam monitor chamber using a pair of slits

    SciTech Connect

    Kubo, H.

    1989-03-01

    A contribution to field-size dependent output by backscattered radiation (BSR) from secondary collimator jaws to a beam monitor chamber of a linear accelerator was measured with a Farmer ionization chamber, positioned 200 cm from the source behind a low-melting-point alloy slab with a 10-cm wide slit. Another slit was positioned against the collimator jaws. Both slits were in the form of a 6.3-mm-diam hole in the middle and were aligned to the source. The use of a pair of slits was intended to eliminate any influence on the ion chamber readings due to field-size dependent charge contribution from the flattening filter and collimator jaw forward scattering. In addition, the setup permits to observe the degree of field-size dependence on BSR. Charge measurements from the Therac-20 18-MV x rays showed a 7.5% field-size dependence on BSR whereas 6- and 18-MV x rays from Varian Clinac-1800 showed <2% dependence on BSR. The telescopic method was found to be easy to use and permitted direct determination of BSR contributions.

  16. Telescopic measurements of backscattered radiation from secondary collimator jaws to a beam monitor chamber using a pair of slits.

    PubMed

    Kubo, H

    1989-01-01

    A contribution to field-size dependent output by backscattered radiation (BSR) from secondary collimator jaws to a beam monitor chamber of a linear accelerator was measured with a Farmer ionization chamber, positioned 200 cm from the source behind a low-melting-point alloy slab with a 10-cm wide slit. Another slit was positioned against the collimator jaws. Both slits were in the form of a 6.3-mm-diam hole in the middle and were aligned to the source. The use of a pair of slits was intended to eliminate any influence on the ion chamber readings due to field-size dependent charge contribution from the flattening filter and collimator jaw forward scattering. In addition, the setup permits to observe the degree of field-size dependence on BSR. Charge measurements from the Therac-20 18-MV x rays showed a 7.5% field-size dependence on BSR whereas 6- and 18-MV x rays from Varian Clinac-1800 showed less than 2% dependence on BSR. The telescopic method was found to be easy to use and permitted direct determination of BSR contributions.

  17. Long slit spectropolarimetry of Jupiter and Saturn

    NASA Astrophysics Data System (ADS)

    Schmid, H. M.; Joos, F.; Buenzli, E.; Gisler, D.

    2011-04-01

    We present ground-based limb polarization measurements of Jupiter and Saturn consisting of full disk imaging polarimetry for the wavelength 7300 Å and spatially resolved (long-slit) spectropolarimetry covering the wavelength range 5200-9350 Å. For the polar region of Jupiter we find for λ = 6000 Å a very strong radial (perpendicular to the limb) fractional polarization with a seeing corrected maximum of about +11.5% in the South and +10.0% in the North. This indicates that the polarizing haze layer is thicker at the South pole. The polar haze layers extend down to 58° in latitude. The derived polarization values are much higher than reported in previous studies because of the better spatial resolution of our data and an appropriate consideration of the atmospheric seeing. Model calculations demonstrate that the high limb polarization can be explained by strongly polarizing ( p ≈ 1.0), high albedo ( ω ≈ 0.98) haze particles with a scattering asymmetry parameter of g ≈ 0.6 as expected for aggregate particles of the type described by West and Smith (West, R.A., Smith, P.H. [1991]. Icarus 90, 330-333). The deduced particle parameters are distinctively different when compared to lower latitude regions. The spectropolarimetry of Jupiter shows a decrease in the polar limb polarization towards longer wavelengths and a significantly enhanced polarization in strong methane bands when compared to the adjacent continuum. This is a natural outcome for a highly polarizing haze layer above an atmosphere where multiple scatterings are suppressed in absorption bands. For lower latitudes the fractional polarization is small, negative, and it depends only little on wavelength except for the strong CH 4-band at 8870 Å. The South pole of Saturn shows a lower polarization ( p ≈ 1.0-1.5%) than the poles of Jupiter. The spectropolarimetric signal for Saturn decrease rapidly with wavelength and shows no significant enhancements in the fractional polarization in the

  18. Linear models for airborne-laser-scanning-based operational forest inventory with small field sample size and highly correlated LiDAR data

    USGS Publications Warehouse

    Junttila, Virpi; Kauranne, Tuomo; Finley, Andrew O.; Bradford, John B.

    2015-01-01

    Modern operational forest inventory often uses remotely sensed data that cover the whole inventory area to produce spatially explicit estimates of forest properties through statistical models. The data obtained by airborne light detection and ranging (LiDAR) correlate well with many forest inventory variables, such as the tree height, the timber volume, and the biomass. To construct an accurate model over thousands of hectares, LiDAR data must be supplemented with several hundred field sample measurements of forest inventory variables. This can be costly and time consuming. Different LiDAR-data-based and spatial-data-based sampling designs can reduce the number of field sample plots needed. However, problems arising from the features of the LiDAR data, such as a large number of predictors compared with the sample size (overfitting) or a strong correlation among predictors (multicollinearity), may decrease the accuracy and precision of the estimates and predictions. To overcome these problems, a Bayesian linear model with the singular value decomposition of predictors, combined with regularization, is proposed. The model performance in predicting different forest inventory variables is verified in ten inventory areas from two continents, where the number of field sample plots is reduced using different sampling designs. The results show that, with an appropriate field plot selection strategy and the proposed linear model, the total relative error of the predicted forest inventory variables is only 5%–15% larger using 50 field sample plots than the error of a linear model estimated with several hundred field sample plots when we sum up the error due to both the model noise variance and the model’s lack of fit.

  19. Aortic and Hepatic Contrast Enhancement During Hepatic-Arterial and Portal Venous Phase Computed Tomography Scanning: Multivariate Linear Regression Analysis Using Age, Sex, Total Body Weight, Height, and Cardiac Output.

    PubMed

    Masuda, Takanori; Nakaura, Takeshi; Funama, Yoshinori; Higaki, Toru; Kiguchi, Masao; Imada, Naoyuki; Sato, Tomoyasu; Awai, Kazuo

    We evaluated the effect of the age, sex, total body weight (TBW), height (HT) and cardiac output (CO) of patients on aortic and hepatic contrast enhancement during hepatic-arterial phase (HAP) and portal venous phase (PVP) computed tomography (CT) scanning. This prospective study received institutional review board approval; prior informed consent to participate was obtained from all 168 patients. All were examined using our routine protocol; the contrast material was 600 mg/kg iodine. Cardiac output was measured with a portable electrical velocimeter within 5 minutes of starting the CT scan. We calculated contrast enhancement (per gram of iodine: [INCREMENT]HU/gI) of the abdominal aorta during the HAP and of the liver parenchyma during the PVP. We performed univariate and multivariate linear regression analysis between all patient characteristics and the [INCREMENT]HU/gI of aortic- and liver parenchymal enhancement. Univariate linear regression analysis demonstrated statistically significant correlations between the [INCREMENT]HU/gI and the age, sex, TBW, HT, and CO (all P < 0.001). However, multivariate linear regression analysis showed that only the TBW and CO were of independent predictive value (P < 0.001). Also, only the CO was independently and negatively related to aortic enhancement during HAP and to liver parenchymal enhancement when the contrast material injection protocol was adjusted for the TBW (P < 0.001). By multivariate linear regression analysis only the TBW and CO were significantly correlated with aortic and liver parenchymal enhancement; the age, sex, and HT were not. The CO was the only independent factor affecting aortic and liver parenchymal enhancement at hepatic CT when the protocol was adjusted for the TBW.

  20. Perspectives of SLIT/ROBO signaling in placental angiogenesis.

    PubMed

    Liao, Wu-xiang; Wing, Deborah A; Geng, Jian-Guo; Chen, Dong-bao

    2010-09-01

    A novel family of evolutionally conserved neuronal guidance cues, including ligands (i.e., Slit, netrin, epherin, and semaphorin) and their corresponding receptors (i.e., Robo, DCC/Unc5, Eph and plexin/ neuropilin), has been identified to play a crucial role in axon pathfinding and branching as well as neuronal cell migration. The presence of commonalities in both neural and vascular developments has led to some exciting discoveries recently, which have extended the functions of these systems to vascular formation (vasculogenesis) and development (angiogenesis). Some of these ligands and receptors have been found to be expressed in the vasculature and surrounding tissues in physiological and pathological conditions. It is postulated that they regulate the formation and integrity of blood vessels. In particular, it has been shown that the Slit/Robo pair plays a novel role in angiogenesis during tumorigenesis and vascular formation during embryogenesis. Herein we summarize briefly the characteristics of this family of neuronal guidance molecules and discuss the extra-neural expression and function of the Slit/Robo pair in angiogenesis in physiological and pathological settings. We report expression of Robo1 protein in capillary endothelium and co-expression of Slit2 and Robo1 proteins in syncytiotrophoblast in healthy term human placental villi. These cellular expression patterns implicate that the Slit/Robo signaling plays an autocrine and/or paracrine role in angiogenesis and trophoblast functions. We also speculate a possible role of this system in pathophysiological placental angiogenesis.

  1. Function of Slit/Robo signaling in breast cancer.

    PubMed

    Gu, Feng; Ma, Yongjie; Zhang, Jiao; Qin, Fengxia; Fu, Li

    2015-12-01

    Slit and Robo are considered tumor suppressors because they are frequently inactivated in various tumor tissue. These genes are closely correlated with CpG hypermethylation in their promoters. The Slit/Robo signaling pathway is reportedly involved in breast cancer development and metastasis. Overexpression of Slit/ Robo induces its tumor suppressive effects possibly by inactivating the β-catenin/LEF/TCF and PI3K/Akt signaling pathways or by altering β-catenin/E-cadherin-mediated cell-cell adhesion in breast cancer cells. Furthermore, loss of Slit proteins or their Robo receptors upregulates the CXCL12/CXCR4 signaling axis in human breast carcinoma. In addition, this pathway regulates the distant migration of breast cancer cells not only by mediating the phosphorylation of the downstream molecules of CXCL12/CXCR4 and srGAPs, such as PI3K/ Src, RAFTK/ Pyk2, and CDC42, but also by regulating the activities of MAP kinases. This review includes recent studies on the functions of Slit/Robo signaling in breast cancer and its molecular mechanisms.

  2. Weighted slit extraction of low-dispersion IUE spectral data

    NASA Technical Reports Server (NTRS)

    Kinney, A. L.; Bohlin, R. C.; Neill, J. D.

    1991-01-01

    The weighted slit extraction has been chosen by the IUE project as the standard extraction for low-dispersion spectra in the final IUE archives. In order to properly weight the data within the extraction slit and obtain the optimal evaluation of the true spectrum, a noise model is derived for IUE data. The exclusion of cosmic rays is demonstrated and the improvement in signal-to-noise ratio is quantified for spectra taken with a wide range of flux level. Problematic spectra, such as trailed spectra, multiple spectra, discontinuous spectra, and emission-line spectra, are extracted to demonstrate the robust nature of the method. Comparisons are made between the standard IUE Standard Image Processing System (IUESIPS) extraction, nonstandard narrow slit extraction, trailed IUESIPS extraction, and weighted extraction for these data. Other weighted slit extractions are briefly discussed. The advantages of the weighted slit extraction are: (1) the extraction improves the signal-to-noise ratio of the spectrum while conserving total flux; (2) most of the cosmic rays are automatically removed; (3) the output includes an error estimate for each point in the flux spectrum; and (4) the algorithm can be run in a batch mode that requires no special input parameters.

  3. A simple method for panretinal imaging with the slit lamp.

    PubMed

    Gellrich, Marcus-Matthias

    2016-12-01

    Slit lamp biomicroscopy of the retina with a convex lens is a key procedure in clinical practice. The methods presented enable ophthalmologists to adequately image large and peripheral parts of the fundus using a video-slit lamp and freely available stitching software. A routine examination of the fundus with a slit lamp and a +90 D lens is recorded on a video film. Later, sufficiently sharp still images are identified on the video sequence. These still images are imported into a freely available image-processing program (Hugin, for stitching mosaics together digitally) and corresponding points are marked on adjacent still images with some overlap. Using the digital stitching program Hugin panoramic overviews of the retina can be built which can extend to the equator. This allows to image diseases involving the whole retina or its periphery by performing a structured fundus examination with a video-slit lamp. Similar images with a video-slit lamp based on a fundus examination through a hand-held non-contact lens have not been demonstrated before. The methods presented enable those ophthalmologists without high-end imaging equipment to monitor pathological fundus findings. The suggested procedure might even be interesting for retinological departments if peripheral findings are to be documented which might be difficult with fundus cameras.

  4. Air sampling of mold spores by slit impactors: yield comparison.

    PubMed

    Pityn, Peter J; Anderson, James

    2013-01-01

    The performance of simple slit impactors for air sampling of mold contamination was compared under field conditions. Samples were collected side-by-side, outdoors in quadruplicates with Burkhard (ambient sampler) and Allergenco MK3 spore traps and with two identical Allergenco slit cassettes operated at diverse flow rates of 5 and 15 L/min, respectively. The number and types of mold spores in each sample were quantified by microscopy. Results showed all four single-stage slit impactors produced similar spore yields. Moreover, paired slit cassettes produced similar outcomes despite a three-fold difference in their sampling rate. No measurable difference in the amount or mix of mold spores per m(3)of air was detected. The implications for assessment of human exposures and interpretation of indoor/outdoor fungal burden are discussed. These findings demonstrate that slit cassettes capture most small spores, effectively and without bias, when operated at a range of flow rates including the lower flow rates used for personal sampling. Our findings indicate sampling data for mold spores correlate for different single stage impactor collection methodologies and that data quality is not deteriorated by operating conditions deviating from manufacturers' norms allowing such sampling results to be used for scientific, legal, investigative, or property insurance purposes. The same conclusion may not be applied to other particle sampling instruments and mulit-stage impactors used for ambient particulate sampling, which represent an entirely different scenario. This knowledge may help facilitate comparison between scientific studies where methodological differences exist.

  5. Nanobits: customizable scanning probe tips

    NASA Astrophysics Data System (ADS)

    Rajendra Kumar, R. T.; Hassan, S. U.; Sardan Sukas, O.; Eichhorn, V.; Krohs, F.; Fatikow, S.; Boggild, P.

    2009-09-01

    We present here a proof-of-principle study of scanning probe tips defined by planar nanolithography and integrated with AFM probes using nanomanipulation. The so-called 'nanobits' are 2-4 µm long and 120-150 nm thin flakes of Si3N4 or SiO2, fabricated by electron beam lithography and standard silicon processing. Using a microgripper they were detached from an array and fixed to a standard pyramidal AFM probe or alternatively inserted into a tipless cantilever equipped with a narrow slit. The nanobit-enhanced probes were used for imaging of deep trenches, without visible deformation, wear or dislocation of the tips of the nanobit after several scans. This approach allows an unprecedented freedom in adapting the shape and size of scanning probe tips to the surface topology or to the specific application.

  6. Nanobits: customizable scanning probe tips.

    PubMed

    Rajendra Kumar, R T; Hassan, S U; Sardan Sukas, O; Eichhorn, V; Krohs, F; Fatikow, S; Boggild, P

    2009-09-30

    We present here a proof-of-principle study of scanning probe tips defined by planar nanolithography and integrated with AFM probes using nanomanipulation. The so-called 'nanobits' are 2-4 microm long and 120-150 nm thin flakes of Si(3)N(4) or SiO(2), fabricated by electron beam lithography and standard silicon processing. Using a microgripper they were detached from an array and fixed to a standard pyramidal AFM probe or alternatively inserted into a tipless cantilever equipped with a narrow slit. The nanobit-enhanced probes were used for imaging of deep trenches, without visible deformation, wear or dislocation of the tips of the nanobit after several scans. This approach allows an unprecedented freedom in adapting the shape and size of scanning probe tips to the surface topology or to the specific application.

  7. Nuclear Scans

    MedlinePlus

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  8. Single plane minimal tomography of double slit qubits

    NASA Astrophysics Data System (ADS)

    Chaparro Sogamoso, Edwin C.; Angulo, D.; Fonseca-Romero, K. M.

    2017-09-01

    The determination of the density matrix of an ensemble of identically prepared quantum systems by performing a series of measurements, known as quantum tomography, is minimal when the number of outcomes is minimal. The most accurate minimal quantum tomography of qubits, sometimes called a tetrahedron measurement, corresponds to projections over four states which can be represented on the Bloch sphere as the vertices of a regular tetrahedron. We investigate whether it is possible to implement the tetrahedron measurement of double slit qubits of light, using measurements performed on a single plane. Assuming Gaussian slits and free propagation, we demonstrate that a judicious choice of the detection plane and the double slit geometry allows the implementation of a tetrahedron measurement. Finally, we consider possible sets of values which could be used in actual experiments.

  9. Diffractive patterns superimposed over propagating N-slit interferograms

    NASA Astrophysics Data System (ADS)

    Duarte, F. J.; Taylor, T. S.; Black, A. M.; Olivares, I. E.

    2013-01-01

    Transparent, microscopic spider web silk fibers were used to softly intrude into the propagating path of N-slit interferograms. The resulting interferograms, with superimposed diffractive signals, were recorded using digital means and reproduced using N-slit interferometric calculations. We also show, for the first time, very slight and subtle alterations of the propagating interferograms via the soft insertion of spider web silk fibers into the intra-interferometric path. The experiments were performed at an overall intra-interferometric propagation path length of 7.235 m.

  10. Multiscale Modeling of Red Blood Cells Squeezing through Submicron Slits

    NASA Astrophysics Data System (ADS)

    Peng, Zhangli; Lu, Huijie

    2016-11-01

    A multiscale model is applied to study the dynamics of healthy red blood cells (RBCs), RBCs in hereditary spherocytosis, and sickle cell disease squeezing through submicron slits. This study is motivated by the mechanical filtration of RBCs by inter-endothelial slits in the spleen. First, the model is validated by comparing the simulation results with experiments. Secondly, the deformation of the cytoskeleton in healthy RBCs is investigated. Thirdly, the mechanisms of damage in hereditary spherocytosis are investigated. Finally, the effects of cytoplasm and membrane viscosities, especially in sickle cell disease, are examined. The simulations results provided guidance for future experiments to explore the dynamics of RBCs under extreme deformation.

  11. Nanofabrication and the realization of Feynman's two-slit experiment

    NASA Astrophysics Data System (ADS)

    Frabboni, Stefano; Gazzadi, Gian Carlo; Pozzi, Giulio

    2008-08-01

    Two nanosized slits are opened by focused ion beam milling in a membrane to observe, with a transmission electron microscope, electron interference fringes. Then, on the same sample, one of the slits is closed by focused ion beam induced deposition and the corresponding transmitted intensity is recorded. The comparison between the two measurements provides an impressive experimental evidence of the probability amplitude of quantum mechanics following step by step the original idea proposed by Feynman [The Feynman Lectures on Physics (Addison-Wesley, Reading, MA, 1966), Vol. 3, Chap. 1].

  12. Reflection of a plane shock wave from a slit

    NASA Astrophysics Data System (ADS)

    Serov, A. O.; Shtemenko, L. S.; Shugaev, F. V.

    Laser shadow photography was used in a shock-tube visualization study of a plane shock wave reflected from a slit. The working gases were air and Freon 14, and the Mach number of the incident shock wave was in the 2-3 range. An intense interaction between the reflected wave and the walls of the slit was observed. This interaction could lead to the disappearance of the rectilinear part of this wave, thus reducing the load experienced by the body during this type of reflection.

  13. A simple method to calibrate intensities of photographic slit spectrograms

    NASA Astrophysics Data System (ADS)

    Vogt, N.; Barrera, L. H.

    1985-07-01

    A wavelength-dependent intensity calibration of photographic spectrograms can be obtained through the spectrograph without any additional equipment beyond a simple neutral density filter of known transparency. This filter is introduced in the focal plane of the telescope covering part of the spectrograph slit. Exposure of the comparison lamps through the entire slit yields a calibration plate which shows a well defined density jump within each line. From the height of this jump (for many lines of widely ranging strengths) the characteristic curve can be derived. The method is described and compared to the classical calibration method with a tube sensitometer.

  14. The differential roles of Slit2-exon 15 splicing variants in angiogenesis and HUVEC permeability.

    PubMed

    Yang, Yun-Chiu; Chen, Pei-Ni; Wang, Siou-Yu; Liao, Chen-Yi; Lin, Yu-Ying; Sun, Shih-Rhong; Chiu, Chun-Ling; Hsieh, Yih-Shou; Shieh, Jia-Ching; Chang, Jinghua Tsai

    2015-07-01

    Slit2, a secreted glycoprotein, is down-regulated in many cancers. Slit2/Robo signaling pathway plays an important, but controversial, role in angiogenesis. We identified splicing variants of Slit2 at exon 15, Slit2-WT and Slit2-ΔE15, with differential effects on proliferation and invasive capability of lung cancer cells. The aim of this study was to elucidate the differential roles of these exon 15 splicing variants in angiogenesis. Our results revealed that both Slit2-WT and Slit2-ΔE15 inhibit motility of human umbilical vein endothelial cells (HUVECs). The conditioned medium (CM) collected from CL1-5/VC or CL1-5/Slit2-WT lung adenocarcinoma cells blocked HUVEC tube formation and angiogenesis on chorioallantoic membrane (CAM) assay when compared with untreated HUVECs and CAM, respectively. However, CM of CL1-5/Slit2-ΔE15 restored the quality of tubes and the size of vessels. Although both Slit2-WT and Slit2-ΔE15 inhibited permeability induced by CM of cancer cells, Slit2-ΔE15 exhibited stronger effect. These results suggested that Slit2-ΔE15 plays important roles in normalization of blood vessels by enhancing tube quality and tightening endothelial cells, while Slit2-WT only enhances tightening of endothelial cells. It appears that Robo4 is responsible for Slit2 isoform-mediated inhibition of permeability, while neither Robo1 nor Robo4 is required for Slit2-ΔE15-enhanced tube quality. The results of this study suggest that Slit2-ΔE15 splicing form is a promising molecule for normalizing blood vessels around a tumor, which, in turn, may increase efficacy of chemotherapy and radiotherapy.

  15. SPECIAL ANALYSIS OF OPERATIONAL STORMWATER RUNOFF COVERS OVER SLIT TRENCHES

    SciTech Connect

    Collard, L; Luther Hamm, L

    2008-12-18

    Solid Waste Management (SWM) commissioned this Special Analysis (SA) to determine the effects of placing operational stormwater runoff covers (referred to as covers in the remainder of this document) over slit trench (ST) disposal units ST1 through ST7 (the center set of slit trenches). Previously the United States Department of Energy (DOE) entered into an agreement with the United States Environmental Protection Agency (EPA) and the South Carolina Department of Health and Environmental Control (SCDHEC) to place covers over Slit Trenches 1 and 2 to be able to continue disposing Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) solid waste (see USDOE 2008). Because the covers changed the operating conditions, DOE Order 435.1 (DOE 1999) required that an SA be performed to assess the impact. This Special Analysis has been prepared to determine the effects of placing covers over slit trenches at about years 5, 10 and 15 of the 30-year operational period. Because some slit trenches have already been operational for about 15 years, results from analyzing covers at 5 years and 10 years provide trend analysis information only. This SA also examined alternatives of covering Slit Trenches 1 and 2 with one cover and Slit Trenches 3 and 4 with a second cover versus covering them all with a single cover. Based on modeling results, minimal differences exist between covering Slit Trench groups 1-2 and 3-4 with two covers or one large cover. This SA demonstrates that placement of covers over slit trenches will slow the subsequent release and transport of radionuclides in the vadose zone in the early time periods (from time of placement until about 100 years). Release and transport of some radionuclides in the vadose zone beyond 100 years were somewhat higher than for the case without covers. The sums-of-fractions (SOFs) were examined for the current waste inventory in ST1 and ST2 and for estimated inventories at closure for ST3 through ST7. In all

  16. Rapid detection and identification of N-acetyl-L-cysteine thioethers using constant neutral loss and theoretical multiple reaction monitoring combined with enhanced product-ion scans on a linear ion trap mass spectrometer.

    PubMed

    Scholz, Karoline; Dekant, Wolfgang; Völkel, Wolfgang; Pähler, Axel

    2005-12-01

    A sensitive and specific liquid chromatography-mass spectrometry (LC-MS) method based on the combination of constant neutral loss scans (CNL) with product ion scans was developed on a linear ion trap. The method is applicable for the detection and identification of analytes with identical chemical substructures (such as conjugates of xenobiotics formed in biological systems) which give common CNLs. A specific CNL was observed for thioethers of N-acetyl-L-cysteine (mercapturic acids, MA) by LC-MS/MS. MS and HPLC parameters were optimized with 16 MAs available as reference compounds. All of these provided a CNL of 129 Da in the negative-ion mode. To assess sensitivity, a multiple reaction monitoring (MRM) mode with 251 theoretical transitions using the CNL of 129 Da combined with a product ion scan (IDA thMRM) was compared with CNL combined with a product ion scan (IDA CNL). An information-dependent acquisition (IDA) uses a survey scan such as MRM (multiple reaction monitoring) to generate "informations" and starting a second acquisition experiment such as a product ion scan using these "informations." Th-MRM means calculated transitions and not transitions generated from an available standard in the tuning mode. The product ion spectra provide additional information on the chemical structure of the unknown analytes. All MA standards were spiked in low concentrations to rat urines and were detected with both methods with LODs ranging from 60 pmol/mL to 1.63 nmol/mL with IDA thMRM. The expected product ion spectra were observed in urine. Application of this screening method to biological samples indicated the presence of a number of MAs in urine of unexposed rats, and resulted in the identification of 1,4-dihydroxynonene mercapturic acid as one of these MAs by negative and positive product ion spectra. These results show that the developed methods have a high potential to serve as both a prescreen to detect unknown MAs and to identify these analytes in complex matrix.

  17. Subwavelength beam manipulation via multiple-metal slits coupled by disk-shaped nanocavity

    NASA Astrophysics Data System (ADS)

    Zheng, Gai-Ge; Xu, Lin-Hua; Pei, Shi-Xin; Chen, Yun-Yun

    2014-03-01

    A novel plasmonic structure consisting of three nano-scaled slits coupled by nano-disk-shaped nanocavities is proposed to produce subwavelength focusing and beam bending at optical frequencies. The incident light passes through the metal slits in the form of surface plasmon polaritons (SPPs) and then scatters into radiation fields. Numerical simulations using finite-difference time-domain (FDTD) method show that the transmitted fields through the design example can generate light focusing and deflection by altering the refractive index of the coupled nanocavity. The simulation results indicate that the focal spot is beyond the diffraction limit. Light impinges on the surface at an angle to the optical axis will add an extra planar phase front that interferes with the asymmetric phase front of the plasmonic lens, leading to a larger bending angle off the axial direction. The advantages of the proposed plasmonic lens are smaller device size and ease of fabrication. Such geometries offer the potential to be controlled by using nano-positioning systems for applications in dynamic beam shaping and scanning on the nanoscale.

  18. In-Orbit Performance of MAXI Gas Slit Camera (GSC) on ISS

    NASA Astrophysics Data System (ADS)

    Sugizaki, Mutsumi; Mihara, Tatehiro; Serino, Motoko; Yamamoto, Takayuki; Matsuoka, Masaru; Kohama, Mitsuhiro; Tomida, Hiroshi; Ueno, Shiro; Kawai, Nobuyuki; Morii, Mikio; Sugimori, Kousuke; Nakahira, Satoshi; Yamaoka, Kazutaka; Yoshida, Atsumasa; Nakajima, Motoki; Negoro, Hitoshi; Eguchi, Satoshi; Isobe, Naoki; Ueda, Yoshihiro; Tsunemi, Hiroshi

    2011-11-01

    We report on the in-orbit performance of the Gas Slit Camera (GSC) on the MAXI (Monitor of All-sky X-ray Image) mission carried on the International Space Station (ISS). Its commissioning operation, which started on 2009 August 8, confirmed the basic performances of the effective area in the energy band of 2-30 keV, the spatial resolution of the slit-and-slat collimator and detector with 1.°5 FWHM, the source visibility of 40-150 seconds for each scan cycle, and the sky coverage of 85% per 92-minute orbital period and 95% per day. The gas gains and read-out amplifier gains have been stable within 1%. The background rate is consistent with the past X-ray experiments operated at a similar low-earth orbit if its relation with the geomagnetic cutoff rigidity is extrapolated to high latitude. We also present the status of the in-orbit operation and a calibration of the effective area and the energy response matrix using Crab-nebula data.

  19. Robust scatter correction method for cone-beam CT using an interlacing-slit plate

    NASA Astrophysics Data System (ADS)

    Huang, Kui-Dong; Xu, Zhe; Zhang, Ding-Hua; Zhang, Hua; Shi, Wen-Long

    2016-06-01

    Cone-beam computed tomography (CBCT) has been widely used in medical imaging and industrial nondestructive testing, but the presence of scattered radiation will cause significant reduction of image quality. In this article, a robust scatter correction method for CBCT using an interlacing-slit plate (ISP) is carried out for convenient practice. Firstly, a Gaussian filtering method is proposed to compensate the missing data of the inner scatter image, and simultaneously avoid too-large values of calculated inner scatter and smooth the inner scatter field. Secondly, an interlacing-slit scan without detector gain correction is carried out to enhance the practicality and convenience of the scatter correction method. Finally, a denoising step for scatter-corrected projection images is added in the process flow to control the noise amplification The experimental results show that the improved method can not only make the scatter correction more robust and convenient, but also achieve a good quality of scatter-corrected slice images. Supported by National Science and Technology Major Project of the Ministry of Industry and Information Technology of China (2012ZX04007021), Aeronautical Science Fund of China (2014ZE53059), and Fundamental Research Funds for Central Universities of China (3102014KYJD022)

  20. Changes in intracranial pressure after calvarial expansion surgery in children with slit ventricle syndrome.

    PubMed

    Eide, P K; Helseth, E; Due-Tønnessen, B; Lundar, T

    2001-10-01

    The effect of calvarial expansion on symptom relief and intracranial pressure (ICP) in three children with slit ventricle syndrome (SVS) and intracranial hypertension despite a functioning ventricular shunt is reported. These children presented with a clinical picture of SVS, accompanied by slit-like ventricles on cranial computer tomography scan and intracranial hypertension. Calvarial expansion was performed by mans of an anterior approach in one case and a posterior approach (modified tiara plastic) in the other two cases. After calvarial expansion, symptoms of intracranial hypertension were abolished in one case and markedly reduced in two cases (observation period 25-36 months). Comparison of ICP before and after surgery was performed by means of new software (Sensometrics Pressure Analyser, version 1.2) that revealed a significant reduction in the number of abnormal ICP elevations after surgery. The results were not accompanied by changes in the size of the cerebral ventricles. This study demonstrates that in children with SVS and intracranial hypertension despite a functioning shunt, calvarial expansion may reduce ICP and produce long-lasting symptom relief. In these cases, we suggest that intracranial hypertension was caused by compromised intracranial volume. Copyright 2001 S. Karger AG, Basel

  1. Slit-Robo signaling mediates lymphangiogenesis and promotes tumor lymphatic metastasis.

    PubMed

    Yang, Xiao-Mei; Han, Hai-Xiong; Sui, Fei; Dai, Yu-Min; Chen, Ming; Geng, Jian-Guo

    2010-05-28

    The Slit family of guidance cues binds to Roundabout (Robo) receptors to modulate neuronal, leukocytic, and endothelial migration. Slit-Robo signaling had been reported to function as chemoattractive signal for vascular endothelial cells during angiogenesis. In this study, we found that Robo1 was expressed in lymphatic endothelial cells to mediate the migration and tube formation of these cells upon Slit2 stimulation, which were specifically inhibited by the function-blocking antibody R5 to Slit2/Robo1 interaction. To further explore the lymphangiogenic effect and significance mediated by Slit-Robo signaling, we intercrossed Slit2 transgenic mice with a non-metastatic RIP1-Tag2 mouse tumor model, and found that transgenic overexpression of Slit2 significantly enhanced tumor lymphangiogenesis and subsequently promoted mesenteric lymph node metastasis of pancreatic islet tumors. Taken together, our findings reveal that through interacting with Robo1, Slit2 is a novel and potent lymphangiogenic factor and contributes to tumor lymphatic metastasis.

  2. The nephridial hypothesis of the gill slit origin.

    PubMed

    Ezhova, Olga V; Malakhov, Vladimir V

    2015-12-01

    Metameric gill slits are mysterious structures, unique for Chordata and Hemichordata, and also, perhaps, for the extinct Cambrian Calcichordata. There is a discussed hypothesis of the gill slits origin from the metameric nephridia. According to the hypothesis, the hypothetical metameric deuterostome ancestor had in each segment a pair of coelomoducts and a pair of intestinal pockets. In the anterior segments, the coelomoducts have fused with the intestinal pockets. As a result, each nephridium opened both into the gut and into the environment. Then the dissepiments and funnels reduced in all segments except the collar one. Thus, in recent enteropneusts, only the first pair of gill slits keeps the ancestral arrangement communicating at the same time with the gut, with the environment, and with the coelom of the preceding (collar) segment. In the anterior part of the branchio-genital trunk region of enteropneusts, the metameric intestinal pockets remained, as well as the metameric coelomoducts functioning as the ducts of the metameric gonads, i.e., as the gonoducts. The consequence of the hypothesis is that the metameric gill pores originate from the metameric excreting pores, and the metameric branchial sacs originate from the metameric endodermal pockets of the gut fused with the coelomoducts. The metameric gill slits by themselves correspond with metameric openings connecting the gut with metameric intestinal pockets. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 647-652, 2015. © 2015 Wiley Periodicals, Inc.

  3. Factoring integers with Young's N-slit interferometer

    NASA Astrophysics Data System (ADS)

    Clauser, John F.; Dowling, Jonathan P.

    1996-06-01

    We show that a Young's N-slit interferometer can be used to factor the integer N. The device could factor four- or five-digit numbers in a practical fashion. This work shows how number theory may arise in physical problems, and may provide some insight as to how quantum computers can carry out factoring problems by interferometric means.

  4. A Variant of Young's Double Slit Experiment for Educational Purposes

    ERIC Educational Resources Information Center

    Henault, Francois; Spang, Alain

    2011-01-01

    We describe a variant of the classical Young's double slit experiment that can be easily realized in any classroom, in order to evidence the wave nature of light. The proposed apparatus and its simplified theory are described and pictures of fringes, readily obtained using only cheap and off-the-shelf optical components, are reproduced. The…

  5. Slit-Robo Repulsive Signaling Extrudes Tumorigenic Cells from Epithelia.

    PubMed

    Vaughen, John; Igaki, Tatsushi

    2016-12-19

    Cells dynamically interact throughout animal development to coordinate growth and deter disease. For example, cell-cell competition weeds out aberrant cells to enforce homeostasis. In Drosophila, tumorigenic cells mutant for the cell polarity gene scribble (scrib) are actively eliminated from epithelia when surrounded by wild-type cells. While scrib cell elimination depends critically on JNK signaling, JNK-dependent cell death cannot sufficiently explain scrib cell extirpation. Thus, how JNK executed cell elimination remained elusive. Here, we show that repulsive Slit-Robo2-Ena signaling exerts an extrusive force downstream of JNK to eliminate scrib cells from epithelia by disrupting E-cadherin. While loss of Slit-Robo2-Ena in scrib cells potentiates scrib tumor formation within the epithelium, Robo2-Ena hyperactivation surprisingly triggers luminal scrib tumor growth following excess extrusion. This extrusive signaling is amplified by a positive feedback loop between Slit-Robo2-Ena and JNK. Our observations provide a potential causal mechanism for Slit-Robo dysregulation in numerous human cancers.

  6. A Portable Double-Slit Quantum Eraser with Individual Photons

    ERIC Educational Resources Information Center

    Dimitrova, T. L.; Weis, A.

    2011-01-01

    The double-slit experiment has played an important role in physics, from supporting the wave theory of light, via the discussions of the wave-particle duality of light (and matter) to the foundations of modern quantum optics. Today it keeps playing an active role in the context of quantum optics experiments involving single photons. In this paper,…

  7. A Spreadsheet Simulation for a Young's Double Slits Experiment.

    ERIC Educational Resources Information Center

    Field, Richard

    1995-01-01

    Describes a spreadsheet that can be used to show the changes in intensity of Fraunhofer diffraction patterns produced by a single and double slits arrangement. Discusses a practical demonstration of diffraction that allows data to be logged and entered into the spreadsheet. (DDR)

  8. A Variant of Young's Double Slit Experiment for Educational Purposes

    ERIC Educational Resources Information Center

    Henault, Francois; Spang, Alain

    2011-01-01

    We describe a variant of the classical Young's double slit experiment that can be easily realized in any classroom, in order to evidence the wave nature of light. The proposed apparatus and its simplified theory are described and pictures of fringes, readily obtained using only cheap and off-the-shelf optical components, are reproduced. The…

  9. A Portable Double-Slit Quantum Eraser with Individual Photons

    ERIC Educational Resources Information Center

    Dimitrova, T. L.; Weis, A.

    2011-01-01

    The double-slit experiment has played an important role in physics, from supporting the wave theory of light, via the discussions of the wave-particle duality of light (and matter) to the foundations of modern quantum optics. Today it keeps playing an active role in the context of quantum optics experiments involving single photons. In this paper,…

  10. Laser-scan lithography onto ultra-fine pipes 100 μm in diameter

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroshi; Sagara, Tomoya; Horiuchi, Toshiyuki

    2016-05-01

    It is required to develop a simple but effective method for fabricating micro components with cylindrical shapes such as spring parts used for contact-probe springs of electrical testing systems. Here, laser-scan lithography was researched for printing fine resist patterns used for etching masks on ultra-fine stainless-steel pipes with a diameter of 100 μm. At first, a pipe was coated with 3-μm thick positive resist. Second, the resist is exposed to laser light. As the laser light source, a violet laser with a wavelength of 408 nm was used. The laser beam was reshaped in a circle, and irradiated on the pipe by reducing it in 1/20 using a reduction projection optics composed of a 10X objective lens and a 2X imaging lens. The pipe was supported by the chuck of rotation stage, and exposured by moving it up and down and rotating it. The pipe position was adjusted as the laser spot came on the pipe center using the XY stage. Linearly arrayed 22 slit patterns with a length of 180 μm and a separation of 70μm were printed at each 90° rotation angle. That is, 88 slits in total were delineated at an exposure speed of 110 μm/s.

  11. A multiscale transport model for binary Lennard Jones mixtures in slit nanopores

    NASA Astrophysics Data System (ADS)

    Bhadauria, Ravi; Aluru, N. R.

    2016-11-01

    We present a quasi-continuum multiscale hydrodynamic transport model for one dimensional isothermal, non-reacting binary mixture confined in slit shaped nanochannels. We focus on species transport equation that includes the viscous dissipation and interspecies diffusion term of the Maxwell-Stefan form. Partial viscosity variation is modeled by van der Waals one fluid approximation and the Local Average Density Method. We use friction boundary conditions where the wall-species friction parameter is computed using a novel species specific Generalized Langevin Equation model. The transport model accuracy is tested by predicting the velocity profiles of Lennard-Jones (LJ) methane-hydrogen and LJ methane-argon mixtures in graphene slit channels of different width. The resultant slip length from the continuum model is found to be invariant of channel width for a fixed mixture molar concentration. The mixtures considered are observed to behave as single species pseudo fluid, with the friction parameter displaying a linear dependence on the molar composition. The proposed model yields atomistic level accuracy with continuum scale efficiency.

  12. Towards clinical application: prompt gamma imaging of passively scattered proton fields with a knife-edge slit camera

    NASA Astrophysics Data System (ADS)

    Priegnitz, M.; Barczyk, S.; Nenoff, L.; Golnik, C.; Keitz, I.; Werner, T.; Mein, S.; Smeets, J.; Vander Stappen, F.; Janssens, G.; Hotoiu, L.; Fiedler, F.; Prieels, D.; Enghardt, W.; Pausch, G.; Richter, C.

    2016-11-01

    Prompt γ-ray imaging with a knife-edge shaped slit camera provides the possibility of verifying proton beam range in tumor therapy. Dedicated experiments regarding the characterization of the camera system have been performed previously. Now, we aim at implementing the prototype into clinical application of monitoring patient treatments. Focused on this goal of translation into clinical operation, we systematically addressed remaining challenges and questions. We developed a robust energy calibration routine and corresponding quality assurance protocols. Furthermore, with dedicated experiments, we determined the positioning precision of the system to 1.1 mm (2σ). For the first time, we demonstrated the application of the slit camera, which was intentionally developed for pencil beam scanning, to double scattered proton beams. Systematic experiments with increasing complexity were performed. It was possible to visualize proton range shifts of 2-5 mm with the camera system in phantom experiments in passive scattered fields. Moreover, prompt γ-ray profiles for single iso-energy layers were acquired by synchronizing time resolved measurements to the rotation of the range modulator wheel of the treatment system. Thus, a mapping of the acquired profiles to different anatomical regions along the beam path is feasible and additional information on the source of potential range shifts can be obtained. With the work presented here, we show that an application of the slit camera in clinical treatments is possible and of potential benefit.

  13. Towards clinical application: prompt gamma imaging of passively scattered proton fields with a knife-edge slit camera.

    PubMed

    Priegnitz, M; Barczyk, S; Nenoff, L; Golnik, C; Keitz, I; Werner, T; Mein, S; Smeets, J; Vander Stappen, F; Janssens, G; Hotoiu, L; Fiedler, F; Prieels, D; Enghardt, W; Pausch, G; Richter, C

    2016-11-21

    Prompt γ-ray imaging with a knife-edge shaped slit camera provides the possibility of verifying proton beam range in tumor therapy. Dedicated experiments regarding the characterization of the camera system have been performed previously. Now, we aim at implementing the prototype into clinical application of monitoring patient treatments. Focused on this goal of translation into clinical operation, we systematically addressed remaining challenges and questions. We developed a robust energy calibration routine and corresponding quality assurance protocols. Furthermore, with dedicated experiments, we determined the positioning precision of the system to 1.1 mm (2σ). For the first time, we demonstrated the application of the slit camera, which was intentionally developed for pencil beam scanning, to double scattered proton beams. Systematic experiments with increasing complexity were performed. It was possible to visualize proton range shifts of 2-5 mm with the camera system in phantom experiments in passive scattered fields. Moreover, prompt γ-ray profiles for single iso-energy layers were acquired by synchronizing time resolved measurements to the rotation of the range modulator wheel of the treatment system. Thus, a mapping of the acquired profiles to different anatomical regions along the beam path is feasible and additional information on the source of potential range shifts can be obtained. With the work presented here, we show that an application of the slit camera in clinical treatments is possible and of potential benefit.

  14. Role of intensity fluctuations in third-order correlation double-slit interference of thermal light.

    PubMed

    Chen, Xi-Hao; Chen, Wen; Meng, Shao-Ying; Wu, Wei; Wu, Ling-An; Zhai, Guang-Jie

    2013-07-01

    A third-order double-slit interference experiment with a pseudothermal light source in the high-intensity limit has been performed by actually recording the intensities in three optical paths. It is shown that not only can the visibility be dramatically enhanced compared to the second-order case as previously theoretically predicted and shown experimentally, but also that the higher visibility is a consequence of the contribution of third-order correlation interaction terms, which is equal to the sum of all contributions from second-order correlation. It is interesting that, when the two reference detectors are scanned in opposite directions, negative values for the third-order correlation term of the intensity fluctuations may appear. The phenomenon can be completely explained by the theory of classical statistical optics and is the first concrete demonstration of the influence of the third-order correlation terms.

  15. CT Scans

    MedlinePlus

    ... cross-sectional pictures of your body. Doctors use CT scans to look for Broken bones Cancers Blood clots Signs of heart disease Internal bleeding During a CT scan, you lie still on a table. The table ...

  16. Transduction and adaptation in spider slit sense organ mechanoreceptors.

    PubMed

    Juusola, M; French, A S

    1995-12-01

    1. Mechanoreceptor neurons in spider (Cupiennlus salei) slit sense organ were examined by intracellular current- and voltageclarry recordings. Steps and pseudorandomly modulated displacement stimuli were delivered to the mechanosensitive cuticular slits. The resulting responses were used to determine the response dynamics and signal-to-noise ratio (SNR) of mechanoelectrical transduction. 2. Neurons were separated into two groups that, in terms of their afferent discharges, displayed different adaptations to displacement stimuli. Both responded at the onset of the step but then adapted fully, either immediately or within 10-200 ms. Voltage-clamp recordings showed only small differences in the receptor currents of the two groups. 3. Displacement of the slit caused a large inward current that decayed in seconds to a steady level of approximately 10-25% of the initial transient. When adapted to a steady displacement, the neurons responded to superimposed displacements in the same direction with additional transient currents, whose decay could be fitted by two exponentials with time constants of approximately 10 and 100 ms. In contrast, displacement in the opposite direction caused small "outward" currents without obvious adaptation. This behavior persisted with increasing background displacements, suggesting a shift in the displacement-response curve along the displacement axis. 4. White noise stimulation supported the step data and confirmed that the receptor's sensitivity was independent of mean slit membrane displacement. When the relative displacement of the stimulus (i.e., strain) was held constant at different maintained backgrounds, the SNR of the neurons remained fairly constant at approximately 2-10 over the frequency range from 4 to 450 Hz. The receptor current frequency responses showed high-pass characteristics, with a two- to sevenfold enhancement of the response amplitude and a phase lag relative to the stimulus of 90 degrees at 300 Hz. Low coherence

  17. Degree of polarization in Young's double-slit interference experiment formed by stochastic electromagnetic beams.

    PubMed

    Chen, Ziyang; Pu, Jixiong

    2007-07-01

    We analyze the behavior of the degree of polarization in the interference field of Young's double-slit experiment. We analyze the degree of polarization in Young's double-slit interference experiment illuminated by stochastic electromagnetic beams. The distribution of the degree of polarization in the interference field for different correlation lengths and different slit widths is investigated. Furthermore, it is shown that the degree of polarization for a fixed observation point may take on values different from those it takes in the slits, depending not only on the value of the correlation length but also on the width of the slit.

  18. Snapshot linear-Stokes imaging spectropolarimeter using division-of-focal-plane polarimetry and integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    Mu, Tingkui; Pacheco, Shaun; Chen, Zeyu; Zhang, Chunmin; Liang, Rongguang

    2017-02-01

    In this paper, the design and experimental demonstration of a snapshot linear-Stokes imaging spectropolarimeter (SLSIS) is presented. The SLSIS, which is based on division-of-focal-plane polarimetry with four parallel linear polarization channels and integral field spectroscopy with numerous slit dispersive paths, has no moving parts and provides video-rate Stokes-vector hyperspectral datacubes. It does not need any scanning in the spectral, spatial or polarization dimension and offers significant advantages of rapid reconstruction without heavy computation during post-processing. The principle and the experimental setup of the SLSIS are described in detail. The image registration, Stokes spectral reconstruction and calibration procedures are included, and the system is validated using measurements of tungsten light and a static scene. The SLSIS’s snapshot ability to resolve polarization spectral signatures is demonstrated using measurements of a dynamic scene.

  19. Snapshot linear-Stokes imaging spectropolarimeter using division-of-focal-plane polarimetry and integral field spectroscopy

    PubMed Central

    Mu, Tingkui; Pacheco, Shaun; Chen, Zeyu; Zhang, Chunmin; Liang, Rongguang

    2017-01-01

    In this paper, the design and experimental demonstration of a snapshot linear-Stokes imaging spectropolarimeter (SLSIS) is presented. The SLSIS, which is based on division-of-focal-plane polarimetry with four parallel linear polarization channels and integral field spectroscopy with numerous slit dispersive paths, has no moving parts and provides video-rate Stokes-vector hyperspectral datacubes. It does not need any scanning in the spectral, spatial or polarization dimension and offers significant advantages of rapid reconstruction without heavy computation during post-processing. The principle and the experimental setup of the SLSIS are described in detail. The image registration, Stokes spectral reconstruction and calibration procedures are included, and the system is validated using measurements of tungsten light and a static scene. The SLSIS’s snapshot ability to resolve polarization spectral signatures is demonstrated using measurements of a dynamic scene. PMID:28191819

  20. Snapshot linear-Stokes imaging spectropolarimeter using division-of-focal-plane polarimetry and integral field spectroscopy.

    PubMed

    Mu, Tingkui; Pacheco, Shaun; Chen, Zeyu; Zhang, Chunmin; Liang, Rongguang

    2017-02-13

    In this paper, the design and experimental demonstration of a snapshot linear-Stokes imaging spectropolarimeter (SLSIS) is presented. The SLSIS, which is based on division-of-focal-plane polarimetry with four parallel linear polarization channels and integral field spectroscopy with numerous slit dispersive paths, has no moving parts and provides video-rate Stokes-vector hyperspectral datacubes. It does not need any scanning in the spectral, spatial or polarization dimension and offers significant advantages of rapid reconstruction without heavy computation during post-processing. The principle and the experimental setup of the SLSIS are described in detail. The image registration, Stokes spectral reconstruction and calibration procedures are included, and the system is validated using measurements of tungsten light and a static scene. The SLSIS's snapshot ability to resolve polarization spectral signatures is demonstrated using measurements of a dynamic scene.

  1. Passive control of base pressure on an axisymmetric blunt body using a perimetric slit

    NASA Astrophysics Data System (ADS)

    García de la Cruz, Juan Marcos; Oxlade, Anthony R.; Morrison, Jonathan F.

    2017-04-01

    The effect on the base pressure of a thin slit located at the base edge of a blunt axisymmetric body, communicating an internal cavity with the external flow, is investigated. A parametric study is performed of the effect on base pressure of changes in slit size and cavity depth. The base pressure increases initially with increasing cavity depth, but saturates at a depth which depends on the slit size. The base pressure increases monotonically up to 5 % with increasing slit size for the geometries tested. An upper limit of base pressure recovery of 20 % is extrapolated from the data. It is observed that the main effect of the slit is to reduce the instantaneous pressure asymmetry, which is linked to the total base pressure in a similar fashion for all the slit sizes. As a second-order effect, for highly asymmetric pressure distributions, the slit produces a base pressure increase not associated with the base pressure asymmetry. The results suggest a global effect of the slit on the wake due to a diametrical flow within the cavity driven by the pressure differences across the slit and regulated by the largest of the pressure drops between the slit and cavity. The slit also reduces the periodic base pressure fluctuations, corresponding mainly to the vortex shedding, and increases the rotational speed of the wake.

  2. Evolutionarily Conserved Repulsive Guidance Role of Slit in the Silkworm Bombyx mori

    PubMed Central

    Liu, Chun; Cui, Wei-Zheng; Mu, Zhi-Mei; Zhao, Xiao; Liu, Qing-Xin

    2014-01-01

    Axon guidance molecule Slit is critical for the axon repulsion in neural tissues, which is evolutionarily conserved from planarians to humans. However, the function of Slit in the silkworm Bombyx mori was unknown. Here we showed that the structure of Bombyx mori Slit (BmSlit) was different from that in most other species in its C-terminal sequence. BmSlit was localized in the midline glial cell, the neuropil, the tendon cell, the muscle and the silk gland and colocalized with BmRobo1 in the neuropil, the muscle and the silk gland. Knock-down of Bmslit by RNA interference (RNAi) resulted in abnormal development of axons and muscles. Our results suggest that BmSlit has a repulsive role in axon guidance and muscle migration. Moreover, the localization of BmSlit in the silk gland argues for its important function in the development of the silk gland. PMID:25285792

  3. Video recording true single-photon double-slit interference

    NASA Astrophysics Data System (ADS)

    Aspden, Reuben S.; Padgett, Miles J.; Spalding, Gabriel C.

    2016-09-01

    Commercially available cameras do not have a low-enough dark noise to directly capture double-slit interference at the single photon level. In this work, camera noise levels are significantly reduced by activating the camera only when the presence of a photon has been detected by the independent detection of a time-correlated photon produced via parametric down-conversion. This triggering scheme provides the improvement required for direct video imaging of Young's double-slit experiment with single photons, allowing clarified versions of this foundational demonstration. We present video data of the evolving interference patterns. Also, we introduce variations on this experiment aimed at promoting discussion of the role spatial coherence plays in such a measurement, emphasizing complementary aspects of single-photon measurement and highlighting the roles of transverse position and momentum correlations between down-converted photons, including examples of "ghost" imaging and diffraction.

  4. Virtual cathode microwave generator having annular anode slit

    DOEpatents

    Kwan, Thomas J. T.; Snell, Charles M.

    1988-01-01

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

  5. Long-Slit Spectra of Mars in the Thermal Infrared

    NASA Technical Reports Server (NTRS)

    Rowland, C. M.; Sloan, G. C.; Roush, T.; Witteborn, Fred C. (Technical Monitor)

    1994-01-01

    We have obtained long-slit spectra of Mars in the 7-14 micrometer regime. Our two integrations, taken 1993 March 2, are spaced about 2 hours apart and are centered at longitudes of roughly 210 and 240 degrees. The data cover the Elysium Planitia and volcanic regions, the classical dark albedo regions of Cerburus and central and eastern Hesperia, and the classical bright albedo region Utopia Planitia. We have deconvolved the point spread function from the images using a maximum entropy reconstruction algorithm; the resulting spatial resolution of the images is better than 1". Mars occupies approximately 9" of the slit, and we have detected variations in the spectral emission from different areas of the planet. We are in the process of interpreting these spectral variations in terms of the temperature and composition of the surface and the transmission of the Martian atmospheric dust and gases.

  6. Slit ventricle syndrome: a case report of intermittent intracranial hypertension.

    PubMed

    Agarwal, Nitin; Vernier, Eric; Ravenscroft, Sheri; Schwartz, Lauren; Oleske, James; Ming, Xue

    2013-06-01

    Slit ventricle syndrome is a rare condition whereby brain compliance is reduced and can be associated with intermittent intracranial hypertension. A 19-year-old male with a ventriculoperitoneal shunt for congenital hydrocephalus presented with a 1-day history of headache and drowsiness-symptoms from which he suffered in many recurrent episodes over the past 5 years. The improvement of headaches without surgical intervention led to the diagnosis of migraine. During this hospitalization, episodes of intermittent intracranial hypertension were documented along with the remission and relapse of the symptoms. While the patient's intracranial pressure was within normal range in over 90% of his monitoring period, which postponed shunting, replacement of his ventriculoperitoneal shut eventually resolved his symptoms. Slit ventricle syndrome with reduced ventricular compliances should be considered in patients with clinical evidence of intermittent intracranial hypertension and small ventricular size. The authors advocate shunt replacement as an appropriate treatment for this condition.

  7. Long-slit spectra of Mars in the thermal infrared

    NASA Astrophysics Data System (ADS)

    Rowland, C. M.; Sloan, G. C.; Roush, T.

    1994-12-01

    We have obtained long-slit spectra of Mars in the 7-14 microns regime. Our two integrations, taken 1993 March 2, are spaced about 2 hours apart and are centered at longitudes of roughly 210deg and 240deg . The data cover the Elysium Planitia and volcanic regions, the classical dark albedo regions of Cerburus and central and eastern Hesperia, and the classical bright albedo region Utopia Planitia. We have deconvolved the point spread function from the images using a maximum entropy reconstruction algorithm; the resulting spatial resolution of the images is better than 1''. Mars occupies approximately 9'' of the slit, and we have detected variations in the spectral emission from different areas of the planet. We are in the process of interpreting these spectral variations in terms of the temperature and composition of the surface and the transmission of the Martian atmospheric dust and gases.

  8. Exotic looped trajectories of photons in three-slit interference

    PubMed Central

    Magaña-Loaiza, Omar S; De Leon, Israel; Mirhosseini, Mohammad; Fickler, Robert; Safari, Akbar; Mick, Uwe; McIntyre, Brian; Banzer, Peter; Rodenburg, Brandon; Leuchs, Gerd; Boyd, Robert W.

    2016-01-01

    The validity of the superposition principle and of Born's rule are well-accepted tenants of quantum mechanics. Surprisingly, it has been predicted that the intensity pattern formed in a three-slit experiment is seemingly in contradiction with the most conventional form of the superposition principle when exotic looped trajectories are taken into account. However, the probability of observing such paths is typically very small, thus rendering them extremely difficult to measure. Here we confirm the validity of Born's rule and present the first experimental observation of exotic trajectories as additional paths for the light by directly measuring their contribution to the formation of optical interference fringes. We accomplish this by enhancing the electromagnetic near-fields in the vicinity of the slits through the excitation of surface plasmons. This process increases the probability of occurrence of these exotic trajectories, demonstrating that they are related to the near-field component of the photon's wavefunction. PMID:28008907

  9. Double-Slit Interference Pattern for a Macroscopic Quantum System

    NASA Astrophysics Data System (ADS)

    Naeij, Hamid Reza; Shafiee, Afshin

    2016-12-01

    In this study, we solve analytically the Schrödinger equation for a macroscopic quantum oscillator as a central system coupled to two environmental micro-oscillating particles. Then, the double-slit interference patterns are investigated in two limiting cases, considering the limits of uncertainty in the position probability distribution. Moreover, we analyze the interference patterns based on a recent proposal called stochastic electrodynamics with spin. Our results show that when the quantum character of the macro-system is decreased, the diffraction pattern becomes more similar to a classical one. We also show that, depending on the size of the slits, the predictions of quantum approach could be apparently different with those of the aforementioned stochastic description.

  10. Parity breaking with a nonlinear optical double-slit configuration

    NASA Astrophysics Data System (ADS)

    Paltoglou, Vassilis; Efremidis, Nikolaos K.

    2017-02-01

    We consider an optical nonlinear interferometric setup based on Young's double-slit configuration where a nonlinear material is placed exactly after one of the two slits. We examine the effects of Kerr nonlinearity and multi-photon absorption in the resulting interference pattern. The presence of nonlinearity breaks the transverse spatial symmetry of the system, resulting to a modified intensity pattern at the observation plane as a function of the incident intensity. Our theoretical model, based on the modification of the optical path due to the presence of nonlinearity, is surprisingly accurate in predicting the intensity profile of the main lobes for a wide range of parameters. We discuss about potential applications of our model in nonlinear interferometry. Specifically, we show that it is possible to measure both the multi-photon and the Kerr coefficients of a nonlinear material based on the spatial translation of the interference pattern as a function of the incident intensity.

  11. Dynamics of Polymer Chains Confined in Slit-Like Pores

    NASA Astrophysics Data System (ADS)

    Milchev, Andrey; Binder, Kurt

    1996-01-01

    Monte Carlo simulations of an off-lattice bead sping model of polymer chains are presented, confining the chains between two repulsive parallel planes a distance D apart. Varying the chain length N from N=16 to N=128, we show that under good solvent conditions the chains behave like two-dimensional self-avoiding walks, their mean square gyration radius scales as <~ngle R_g^2ranglepropto N^{2ν} with ν =3/4. The density profile across the slit is independent of N and maximal in the center of the slit. The dynamical properties of the chains are found to be in full agreement with the Rouse model with excluded volume in d=2 dimensions, the relaxation times vary like taupropto N^z with z=2ν+1=5/2, the diffusion constant still being given by D_Npropto 1/N. The dynamical behavior of various mean square displacements is analyzed in detail.

  12. Unwanted reflections during slit lamp assisted binocular indirect ophthalmoscopy

    NASA Astrophysics Data System (ADS)

    Sheehan, Matthew; Goncharov, Alexander

    2011-11-01

    Binocular indirect ophthalmoscopy is a routine ophthalmic examination procedure. Two different apparatus setups are commonly employed; the head/spectacle mounted designs of Schepens and slit lamp assisted ophthalmoscopy, both typically performed through a fundus lens of high positive power. It can be difficult for clinicians to avoid unwanted back reflections primarily emanating from the fundus lens and the pre-corneal tear film, particularly when initially learning the skills required to perform the examination. In this investigation the illumination system of a slit lamp was modified to include a variety of obscuration designs optically conjugate to surfaces responsible for creating unwanted reflections. The modified apparatus was then used to perform binocular indirect ophthalmoscopy on an artificial eye and on real eyes. Clinicians used questionnaires to score the appearance of reflections. The mean scores were similar across all trials, including the control unmodified trial, indicating general consensus that the modified illumination system provided no substantial effect on the perception of these unwanted reflections.

  13. Adaptive slit beam shaping for direct laser written waveguides.

    PubMed

    Salter, P S; Jesacher, A; Spring, J B; Metcalf, B J; Thomas-Peter, N; Simmonds, R D; Langford, N K; Walmsley, I A; Booth, M J

    2012-02-15

    We demonstrate an improved method for fabricating optical waveguides in bulk materials by means of femtosecond laser writing. We use an LC spatial light modulator (SLM) to shape the beam focus by generating adaptive slit illumination in the pupil of the objective lens. A diffraction grating is applied in a strip across the SLM to simulate a slit, with the first diffracted order mapped onto the pupil plane of the objective lens while the zeroth order is blocked. This technique enables real-time control of the beam-shaping parameters during writing, facilitating the fabrication of more complicated structures than is possible using nonadaptive methods. Waveguides are demonstrated in fused silica with a coupling loss to single-mode fibers in the range of 0.2 to 0.5 dB and propagation loss <0.4 dB/cm.

  14. [A ventral slit of the prepuce in phimosis].

    PubMed

    Koudelka, J; Docekalová, S

    1998-09-01

    The appearance of the penis after circumcision is frequently not appreciated favourably by the patients nor their parents. An alternative surgical method in phimosis is a ventral slit of the prepuce. When properly indicated, an almost normal appearance of the prepuce is preserved. This operation was performed in 25 boys. An ideal result, where an almost normal shape of the prepuce is preserved and the latter can be drawn over the glans, was achieved in 19 patients. In four boys the prepuce can be freely drawn over the glans but a slight strangulation ring forms. A relapse of phimosis occurred in two boys. The authors recommend to use ventral slit of the prepuce instead of circumcision in children with phimosis, when the prepuce is sufficiently long. The method is not suitable for short prepuces with cicatricial phimosis.

  15. Exotic looped trajectories of photons in three-slit interference

    NASA Astrophysics Data System (ADS)

    Magaña-Loaiza, Omar S.; de Leon, Israel; Mirhosseini, Mohammad; Fickler, Robert; Safari, Akbar; Mick, Uwe; McIntyre, Brian; Banzer, Peter; Rodenburg, Brandon; Leuchs, Gerd; Boyd, Robert W.

    2016-12-01

    The validity of the superposition principle and of Born's rule are well-accepted tenants of quantum mechanics. Surprisingly, it has been predicted that the intensity pattern formed in a three-slit experiment is seemingly in contradiction with the most conventional form of the superposition principle when exotic looped trajectories are taken into account. However, the probability of observing such paths is typically very small, thus rendering them extremely difficult to measure. Here we confirm the validity of Born's rule and present the first experimental observation of exotic trajectories as additional paths for the light by directly measuring their contribution to the formation of optical interference fringes. We accomplish this by enhancing the electromagnetic near-fields in the vicinity of the slits through the excitation of surface plasmons. This process increases the probability of occurrence of these exotic trajectories, demonstrating that they are related to the near-field component of the photon's wavefunction.

  16. Analysis of electroosmotic flow of power-law fluids in a slit microchannel.

    PubMed

    Zhao, Cunlu; Zholkovskij, Emilijk; Masliyah, Jacob H; Yang, Chun

    2008-10-15

    Electroosmotic flow of power-law fluids in a slit channel is analyzed. The governing equations including the linearized Poisson-Boltzmann equation, the Cauchy momentum equation, and the continuity equation are solved to seek analytical expressions for the shear stress, dynamic viscosity, and velocity distribution. Specifically, exact solutions of the velocity distributions are explicitly found for several special values of the flow behavior index. Furthermore, with the implementation of an approximate scheme for the hyperbolic cosine function, approximate solutions of the velocity distributions are obtained. In addition, a generalized Smoluchowski velocity is introduced by taking into account contributions due to the finite thickness of the electric double layer and the flow behavior index of power-law fluids. Calculations are performed to examine the effects of kappaH, flow behavior index, double layer thickness, and applied electric field on the shear stress, dynamic viscosity, velocity distribution, and average velocity/flow rate of the electroosmotic flow of power-law fluids.

  17. A simple method for simulating viscoelastic fluid flows in slit channel

    NASA Astrophysics Data System (ADS)

    Li, Yong; Zheng, Jianrong; Zhou, Wei

    2011-07-01

    A low-cost semi-analysis finite element technique, named the finite piece method (FPM) is presented in this article. It aims to solve three-dimensional (3D) viscoelastic slit flows. The viscoelastic stress of the fluid is modelled using an K-BKZ integral constitutive equation of the Wagner type. Picard iteration is used to solve non-linear equations. The FPM is tested on flow problems in both planar and contraction channels. The accuracy of the method is assessed by comparing flow distributions and pressure with results obtained by 3D finite element method (FEM). It shows that the solution accuracy is excellent and a substantial amount of computing time and memory requirement can be saved.

  18. A method of measuring the velocity of slit based on machine vision

    NASA Astrophysics Data System (ADS)

    Chen, Man; Liao, Zhijie

    2017-01-01

    In the lithography machine, there is a field diaphragm, which is a kind of edge structure. In the process of exposure, it is linearly synchronous movement with the die, so when developing the slit, it is necessary to measure its movement characteristics precisely. A method of velocity measurement based on machine vision is adopted, by detecting edge position in sequential images, and then through the transformation between image coordinate and world coordinate, the object displacement in real space is calculated and finally instantaneous velocity of the object is got. Firstly, through the simulation model in CODE V, correctness of the measurement principle is verified, Next, some error sources that affect the precision of the machine vision measurement system are analyzed, and corresponding solutions are given.

  19. Finally making sense of the double-slit experiment

    PubMed Central

    Aharonov, Yakir; Cohen, Eliahu; Colombo, Fabrizio; Landsberger, Tomer; Sabadini, Irene; Struppa, Daniele C.; Tollaksen, Jeff

    2017-01-01

    Feynman stated that the double-slit experiment “…has in it the heart of quantum mechanics. In reality, it contains the only mystery” and that “nobody can give you a deeper explanation of this phenomenon than I have given; that is, a description of it” [Feynman R, Leighton R, Sands M (1965) The Feynman Lectures on Physics]. We rise to the challenge with an alternative to the wave function-centered interpretations: instead of a quantum wave passing through both slits, we have a localized particle with nonlocal interactions with the other slit. Key to this explanation is dynamical nonlocality, which naturally appears in the Heisenberg picture as nonlocal equations of motion. This insight led us to develop an approach to quantum mechanics which relies on pre- and postselection, weak measurements, deterministic, and modular variables. We consider those properties of a single particle that are deterministic to be primal. The Heisenberg picture allows us to specify the most complete enumeration of such deterministic properties in contrast to the Schrödinger wave function, which remains an ensemble property. We exercise this approach by analyzing a version of the double-slit experiment augmented with postselection, showing that only it and not the wave function approach can be accommodated within a time-symmetric interpretation, where interference appears even when the particle is localized. Although the Heisenberg and Schrödinger pictures are equivalent formulations, nevertheless, the framework presented here has led to insights, intuitions, and experiments that were missed from the old perspective. PMID:28566499

  20. Young's double-slit interference pattern from a twisted beam

    NASA Astrophysics Data System (ADS)

    Emile, Olivier; Emile, Janine

    2014-10-01

    A wide range of diffractive elements have been used to evaluate the topological charge of Laguerre-Gaussian beams. Here, we show theoretically and experimentally that this charge can be simply and readily measured from the interference pattern in Young's double-slit experiment. It can be evaluated from the twisting order of the interference. The results are confronted with previously published studies. The potentialities of the method are then compared with existing techniques.

  1. Characterization of the actuator of EMIR configurable slit unit

    NASA Astrophysics Data System (ADS)

    Mato Martínez, A.; Núñez Cagigal, M.; Barreto Cabrera, M.; Garzón López, F.; Patrón, J.; Teuwen, M.

    2016-07-01

    EMIR1,2 (Espectrógrafo Multiobjeto Infra-Rojo) is a wide field multi-object spectrograph already installed in the Nasmyth focus of GTC (Gran Telescopio Canarias). It operates in the near-infrared (NIR), in the wavelength range from 0.9 μm to 2.5 μm and it will include several mechanism working in cryogenic conditions. A key component of EMIR is the CSU (Configurable Slit Unit), which is a robotic cryo-mechanism used to generate a multi-slit configuration and a long slit on EMIR focal plane when working in spectroscopic mode. The system has 110 sliding bars which can be configured at cryogenic working temperature to create up to 55 slits with a high position accuracy and repeatability. The movement of the bars is performed by an actuator which allows reaching a relatively high speed for the coarse movement and controllable steps up to 2 microns for the fine positioning. This subsystem has been designed and manufactured by the Dutch company Janssen Precision Engineering (JPE) and the Spanish company NTE-SENER. Afterwards, it was thoroughly verified at the IAC (Instituto de Astrofísica de Canarias) facilities. In this paper, the CSU will be briefly described. One of the more important parts of the CSU is the actuators, which move the bars by means of a stick-slip effect. A set of tests designed for characterizing and improving the robustness and performance of the actuators will be presented. Finally, an overview of the current CSU performance will be presented.

  2. Asymmetric Fraunhofer diffraction from roller-blade slits.

    PubMed

    Libbert, J L; Pitney, J A; Robinson, I K

    1997-05-01

    X-ray diffraction experiments under coherent conditions have been made possible by the development of new sources of synchrotron radiation, but make tough demands on the experimental apparatus. Here we describe the design and initial testing of a precision aperture that uses polished molybdenum rods as the slit blades. The device has an inherent asymmetry which is accurately accounted for by a simple modification to the Fraunhofer diffraction function.

  3. Finally making sense of the double-slit experiment.

    PubMed

    Aharonov, Yakir; Cohen, Eliahu; Colombo, Fabrizio; Landsberger, Tomer; Sabadini, Irene; Struppa, Daniele C; Tollaksen, Jeff

    2017-06-20

    Feynman stated that the double-slit experiment "…has in it the heart of quantum mechanics. In reality, it contains the only mystery" and that "nobody can give you a deeper explanation of this phenomenon than I have given; that is, a description of it" [Feynman R, Leighton R, Sands M (1965) The Feynman Lectures on Physics]. We rise to the challenge with an alternative to the wave function-centered interpretations: instead of a quantum wave passing through both slits, we have a localized particle with nonlocal interactions with the other slit. Key to this explanation is dynamical nonlocality, which naturally appears in the Heisenberg picture as nonlocal equations of motion. This insight led us to develop an approach to quantum mechanics which relies on pre- and postselection, weak measurements, deterministic, and modular variables. We consider those properties of a single particle that are deterministic to be primal. The Heisenberg picture allows us to specify the most complete enumeration of such deterministic properties in contrast to the Schrödinger wave function, which remains an ensemble property. We exercise this approach by analyzing a version of the double-slit experiment augmented with postselection, showing that only it and not the wave function approach can be accommodated within a time-symmetric interpretation, where interference appears even when the particle is localized. Although the Heisenberg and Schrödinger pictures are equivalent formulations, nevertheless, the framework presented here has led to insights, intuitions, and experiments that were missed from the old perspective.

  4. Low pressure drop, multi-slit virtual impactor

    DOEpatents

    Bergman, Werner

    2002-01-01

    Fluid flow is directed into a multiplicity of slit nozzles positioned so that the fluid flow is directed into a gap between the nozzles and (a) a number of receiving chambers and (b) a number of exhaust chambers. The nozzles and chambers are select so that the fluid flow will be separated into a first particle flow component with larger and a second particle flow component with the smaller particles.

  5. Human placental expression of SLIT/ROBO signaling cues: effects of preeclampsia and hypoxia.

    PubMed

    Liao, Wu-Xiang; Laurent, Louise C; Agent, Sally; Hodges, Jennifer; Chen, Dong-Bao

    2012-04-01

    Preeclampsia is characterized by dysfunctional endothelium and impaired angiogenesis. Recent studies suggest that the neuronal guidance SLIT/ROBO system regulates tumor angiogenesis. This study investigated if SLIT and ROBO are differentially expressed in healthy term and preeclamptic placentas and if hypoxia regulates SLIT and ROBO expression in placental trophoblast and endothelial cells. Total RNA and protein were extracted from placental tissues of healthy term (n = 5) and preeclamptic (n = 6) pregnancies and used for SLIT/ROBO expression analyses with reverse transcription-polymerase chain reaction (RT-PCR), real-time quantitative-PCR, and immunoblotting. Paraffin-embedded tissues were processed to localize SLIT/ROBO proteins in placental villi by immunohistochemistry. BeWo choriocarcinoma cells and human umbilical vein endothelial cells (HUVEC) were treated with 2% or 10% oxygen or the hypoxia mimetic deferoxamine mesylate (100 μM) to test if hypoxia regulates SLIT/ROBO expression. SLIT2, SLIT3, ROBO1, and ROBO4 mRNA and proteins were detected in the placenta. SLIT2 and ROBO1 proteins localized in the syncytiotrophoblast, and SLIT3, ROBO1, and ROBO4 in capillary endothelium of the placental villi. Levels of ROBO1 and ROBO4 as well as sFLT1 (soluble fms-like tyrosine kinase-1) proteins were significantly greater in preeclamptic placentas compared to normal controls. Hypoxia significantly increased both mRNA and protein levels of SLIT2 in BeWo cells and of SLIT3, ROBO1, and ROBB4 in HUVEC. Thus, trophoblast and endothelial coexpression of SLIT/ROBO suggests an autocrine/paracrine regulatory system for regulating placental function. Differential expression of SLITs and ROBOs in healthy term and preeclamptic placentas and hypoxia regulation of their expressions in placental cells implicate a potential pathophysiological role for this system in preeclampsia.

  6. Improving FAIMS Sensitivity Using a Planar Geometry with Slit Interfaces

    PubMed Central

    Mabrouki, Ridha; Kelly, Ryan T.; Prior, David C.; Shvartsburg, Alexandre A.; Tang, Keqi; Smith, Richard D.

    2010-01-01

    Differential mobility spectrometry or field asymmetric waveform ion mobility spectrometry (FAIMS) is gaining broad acceptance for analyses of gas-phase ions, especially in conjunction with largely orthogonal separation methods such as mass spectrometry (MS) and/or conventional (drift tube) ion mobility spectrometry. In FAIMS, ions are filtered while passing through a gap between two electrodes that may have planar or curved (in particular, cylindrical) geometry. Despite substantial inherent advantages of the planar configuration and its near-universal adoption in current stand-alone FAIMS devices, commercial FAIMS/MS systems have employed curved FAIMS geometries that could be interfaced to MS more effectively. Here we report a new planar (p-) FAIMS design with slit-shaped entrance and exit apertures that substantially increase ion transmission in and out of the analyzer. The front slit interface effectively couples p-FAIMS to multi-emitter electrospray ionization (ESI) sources, improving greatly the ion current introduced to the device and allowing liquid flow rates up to ~50 μL/min. The back slit interface increases the transmission of ribbon-shaped ion beams output by the p-FAIMS to downstream stages such as a MS. Overall, the ion signal in ESI/FAIMS/MS analyses increases by over an order of magnitude without affecting FAIMS resolution. PMID:19616967

  7. Improving FAIMS sensitivity using a planar geometry with slit interfaces.

    PubMed

    Mabrouki, Ridha; Kelly, Ryan T; Prior, David C; Shvartsburg, Alexandre A; Tang, Keqi; Smith, Richard D

    2009-09-01

    Differential mobility spectrometry or field asymmetric waveform ion mobility spectrometry (FAIMS) is gaining broad acceptance for analyses of gas-phase ions, especially in conjunction with largely orthogonal separation methods such as mass spectrometry (MS) and/or conventional (drift tube) ion mobility spectrometry. In FAIMS, ions are filtered while passing through a gap between two electrodes that may have planar or curved (in particular, cylindrical) geometry. Despite substantial inherent advantages of the planar configuration and its near-universal adoption in current stand-alone FAIMS devices, commercial FAIMS/MS systems have employed curved FAIMS geometries that can be more effectively interfaced to MS. Here we report a new planar (p-) FAIMS design with slit-shaped entrance and exit apertures that substantially increase ion transmission in and out of the analyzer. The entrance slit interface effectively couples p-FAIMS to multi-emitter electrospray ionization (ESI) sources, improving greatly the ion current introduced to the device and allowing liquid flow rates up to approximately 50 microL/min. The exit slit interface increases the transmission of ribbon-shaped ion beams output by the p-FAIMS to downstream stages such as a MS. Overall, the ion signal in ESI/FAIMS/MS analyses increases by over an order of magnitude without affecting FAIMS resolution.

  8. Rapid Prototyping of Nanofluidic Slits in a Silicone Bilayer

    PubMed Central

    Kole, Thomas P.; Liao, Kuo-Tang; Schiffels, Daniel; Ilic, B. Robert; Strychalski, Elizabeth A.; Kralj, Jason G.; Liddle, J. Alexander; Dritschilo, Anatoly; Stavis, Samuel M.

    2015-01-01

    This article reports a process for rapidly prototyping nanofluidic devices, particularly those comprising slits with microscale widths and nanoscale depths, in silicone. This process consists of designing a nanofluidic device, fabricating a photomask, fabricating a device mold in epoxy photoresist, molding a device in silicone, cutting and punching a molded silicone device, bonding a silicone device to a glass substrate, and filling the device with aqueous solution. By using a bilayer of hard and soft silicone, we have formed and filled nanofluidic slits with depths of less than 400 nm and aspect ratios of width to depth exceeding 250 without collapse of the slits. An important attribute of this article is that the description of this rapid prototyping process is very comprehensive, presenting context and details which are highly relevant to the rational implementation and reliable repetition of the process. Moreover, this process makes use of equipment commonly found in nanofabrication facilities and research laboratories, facilitating the broad adaptation and application of the process. Therefore, while this article specifically informs users of the Center for Nanoscale Science and Technology (CNST) at the National Institute of Standards and Technology (NIST), we anticipate that this information will be generally useful for the nanofabrication and nanofluidics research communities at large, and particularly useful for neophyte nanofabricators and nanofluidicists. PMID:26958449

  9. Rapid Prototyping of Nanofluidic Slits in a Silicone Bilayer.

    PubMed

    Kole, Thomas P; Liao, Kuo-Tang; Schiffels, Daniel; Ilic, B Robert; Strychalski, Elizabeth A; Kralj, Jason G; Liddle, J Alexander; Dritschilo, Anatoly; Stavis, Samuel M

    2015-01-01

    This article reports a process for rapidly prototyping nanofluidic devices, particularly those comprising slits with microscale widths and nanoscale depths, in silicone. This process consists of designing a nanofluidic device, fabricating a photomask, fabricating a device mold in epoxy photoresist, molding a device in silicone, cutting and punching a molded silicone device, bonding a silicone device to a glass substrate, and filling the device with aqueous solution. By using a bilayer of hard and soft silicone, we have formed and filled nanofluidic slits with depths of less than 400 nm and aspect ratios of width to depth exceeding 250 without collapse of the slits. An important attribute of this article is that the description of this rapid prototyping process is very comprehensive, presenting context and details which are highly relevant to the rational implementation and reliable repetition of the process. Moreover, this process makes use of equipment commonly found in nanofabrication facilities and research laboratories, facilitating the broad adaptation and application of the process. Therefore, while this article specifically informs users of the Center for Nanoscale Science and Technology (CNST) at the National Institute of Standards and Technology (NIST), we anticipate that this information will be generally useful for the nanofabrication and nanofluidics research communities at large, and particularly useful for neophyte nanofabricators and nanofluidicists.

  10. Experimental demonstration of a quantum shutter closing two slits simultaneously

    NASA Astrophysics Data System (ADS)

    Okamoto, Ryo; Takeuchi, Shigeki

    2016-10-01

    The interference between two paths of a single photon at a double slit is widely considered to be the most paradoxical result of quantum theory. Here is a new interesting question to the phenomenon: can a single shutter simultaneously close two slits by effectively being in a superposition of different locations? Aharonov and Vaidman have shown that it is indeed possible to construct a quantum shutter that can close two slits and reflect a probe photon perfectly when its initial and final states are appropriately selected. Here we report the experimental demonstration of their proposal overcoming the difficulty to realize a ‘quantum shutter’ by employing photonic quantum routers. The reflectance ratio of 0.61 ± 0.027 surpasses the classical limit with 4.1 standard deviation, shedding new light on the unusual physical properties of quantum operations. This experimental demonstration, where the strong measurement and non-local superposition seem co-existing, provides an alternative to weak measurements as a way to explore the nature of quantum physics.

  11. Experimental demonstration of a quantum shutter closing two slits simultaneously

    PubMed Central

    Okamoto, Ryo; Takeuchi, Shigeki

    2016-01-01

    The interference between two paths of a single photon at a double slit is widely considered to be the most paradoxical result of quantum theory. Here is a new interesting question to the phenomenon: can a single shutter simultaneously close two slits by effectively being in a superposition of different locations? Aharonov and Vaidman have shown that it is indeed possible to construct a quantum shutter that can close two slits and reflect a probe photon perfectly when its initial and final states are appropriately selected. Here we report the experimental demonstration of their proposal overcoming the difficulty to realize a ‘quantum shutter’ by employing photonic quantum routers. The reflectance ratio of 0.61 ± 0.027 surpasses the classical limit with 4.1 standard deviation, shedding new light on the unusual physical properties of quantum operations. This experimental demonstration, where the strong measurement and non-local superposition seem co-existing, provides an alternative to weak measurements as a way to explore the nature of quantum physics. PMID:27739465

  12. Experimental demonstration of a quantum shutter closing two slits simultaneously.

    PubMed

    Okamoto, Ryo; Takeuchi, Shigeki

    2016-10-14

    The interference between two paths of a single photon at a double slit is widely considered to be the most paradoxical result of quantum theory. Here is a new interesting question to the phenomenon: can a single shutter simultaneously close two slits by effectively being in a superposition of different locations? Aharonov and Vaidman have shown that it is indeed possible to construct a quantum shutter that can close two slits and reflect a probe photon perfectly when its initial and final states are appropriately selected. Here we report the experimental demonstration of their proposal overcoming the difficulty to realize a 'quantum shutter' by employing photonic quantum routers. The reflectance ratio of 0.61 ± 0.027 surpasses the classical limit with 4.1 standard deviation, shedding new light on the unusual physical properties of quantum operations. This experimental demonstration, where the strong measurement and non-local superposition seem co-existing, provides an alternative to weak measurements as a way to explore the nature of quantum physics.

  13. Smart slit assembly for high-resolution spectrometers in space

    NASA Astrophysics Data System (ADS)

    Guldimann, Benedikt; Minoglou, Kyriaki

    2016-03-01

    This paper introduces a novel imaging spectrometer subsystem concept, the Smart Slit Assembly (SSA), that improves instrument performances and enables new features for future Earth Observation. Derived from CarbonSat (ESA study) requirements, a concept of an SSA based on MEMS micro-shutters/mirrors and associated instrument design aspects are presented. The SSA replaces the classical grating spectrometer slit aperture in the focal plane of the telescope with three core elements, namely an input multimode waveguide array followed by a spatial light modulator (SLM) and an output multimode waveguide array which ends at the slit aperture viewed by the spectrometer. The SLM's in-and-outputs being coupled to waveguide arrays leads to an enhanced SLM with light de-coherence, polarization scrambling and scene/object homogenization capabilities. The additional advantage of this subsystem's arrangement is that waveguide level homogeneous spatial light modulation can be achieved with spatially in-homogeneous coupling from in to output multimode waveguides, allowing new, simpler and less costly designs for the SLM part of the SSA. The SSA is particularly useful for instance to reduce stray light by scene/object selection or modulation (e.g. de-clouding, intensity equalization), relax on the required dynamic range of the detectors, increase spectral stability by waveguide level intensity homogenization/scrambling, continuous in-flight monitoring of the co-registration between two or several spectrometer channels and inflight monitoring of stray light.

  14. A molecular mechanism for the heparan sulfate dependence of slit-robo signaling.

    PubMed

    Hussain, Sadaf-Ahmahni; Piper, Michael; Fukuhara, Noémi; Strochlic, Laure; Cho, Gian; Howitt, Jason A; Ahmed, Yassir; Powell, Andrew K; Turnbull, Jeremy E; Holt, Christine E; Hohenester, Erhard

    2006-12-22

    Slit is a large secreted protein that provides important guidance cues in the developing nervous system and in other organs. Signaling by Slit requires two receptors, Robo transmembrane proteins and heparan sulfate (HS) proteoglycans. How HS controls Slit-Robo signaling is unclear. Here we show that the second leucine-rich repeat domain (D2) of Slit, which mediates binding to Robo receptors, also contains a functionally important binding site for heparin, a highly sulfated variant of HS. Heparin markedly enhances the affinity of the Slit-Robo interaction in a solid-phase binding assay. Analytical gel filtration chromatography demonstrates that Slit D2 associates with a soluble Robo fragment and a heparin-derived oligosaccharide to form a ternary complex. Retinal growth cone collapse triggered by Slit D2 requires cell surface HS or exogenously added heparin. Mutation of conserved basic residues in the C-terminal cap region of Slit D2 reduces heparin binding and abolishes biological activity. We conclude that heparin/HS is an integral component of the minimal Slit-Robo signaling complex and serves to stabilize the relatively weak Slit-Robo interaction.

  15. Expression and roles of Slit/Robo in human ovarian cancer.

    PubMed

    Dai, Cai Feng; Jiang, Yi Zhou; Li, Yan; Wang, Kai; Liu, Pei Shu; Patankar, Manish S; Zheng, Jing

    2011-05-01

    The Slit glycoproteins and their Roundabout (Robo) receptors regulate migration and growth of many types of cells including human cancer cells. However, little is known about the expression and roles of Slit/Robo in human ovarian cancer. Herein, we examined the expression of Slit/Robo in human normal and malignant ovarian tissues and its potential participation in regulating migration and proliferation of human ovarian cancer cells using two ovarian cancer cell lines, OVCAR-3 and SKOV-3. We demonstrated that Slit2/3 and Robo1 were immunolocalized primarily in stromal cells in human normal ovaries and in cancer cells in many histotypes of ovarian cancer tissues. Protein expression of Slit2/3 and Robo1/4 was also identified in OVCAR-3 and SKOV-3 cells. However, recombinant human Slit2 did not significantly affect SKOV-3 cell migration, and OVCAR-3 and SKOV-3 cell proliferation. Slit2 also did not induce ERK1/2 and AKT1 phosphorylation in OVCAR-3 and SKOV-3 cells. The current findings indicate that three major members (Slit2/3 and Robo1) of Slit/Robo family are widely expressed in the human normal and malignant ovarian tissues and in OVCAR-3 and SKOV-3 cells. However, Slit/Robo signaling may not play an important role in regulating human ovarian cancer cell proliferation and migration.

  16. Line-scanning, stage scanning confocal microscope

    NASA Astrophysics Data System (ADS)

    Carucci, John A.; Stevenson, Mary; Gareau, Daniel

    2016-03-01

    We created a line-scanning, stage scanning confocal microscope as part of a new procedure: video assisted micrographic surgery (VAMS). The need for rapid pathological assessment of the tissue on the surface of skin excisions very large since there are 3.5 million new skin cancers diagnosed annually in the United States. The new design presented here is a confocal microscope without any scanning optics. Instead, a line is focused in space and the sample, which is flattened, is physically translated such that the line scans across its face in a direction perpendicular to the line its self. The line is 6mm long and the stage is capable of scanning 50 mm, hence the field of view is quite large. The theoretical diffraction-limited resolution is 0.7um lateral and 3.7um axial. However, in this preliminary report, we present initial results that are a factor of 5-7 poorer in resolution. The results are encouraging because they demonstrate that the linear array detector measures sufficient signal from fluorescently labeled tissue and also demonstrate the large field of view achievable with VAMS.

  17. Renal scan

    MedlinePlus

    ... and urinate often to help remove the radioactive material from the body. How to Prepare for the Test Tell your health care provider if you take ... drink additional fluids before the scan. How the Test will ... into the vein. However, you will not feel the radioactive material. The scanning table may be hard and cold. ...

  18. Prompt gamma imaging with a slit camera for real-time range control in proton therapy.

    PubMed

    Smeets, J; Roellinghoff, F; Prieels, D; Stichelbaut, F; Benilov, A; Busca, P; Fiorini, C; Peloso, R; Basilavecchia, M; Frizzi, T; Dehaes, J C; Dubus, A

    2012-06-07

    Treatments delivered by proton therapy are affected by uncertainties on the range of the beam within the patient, requiring medical physicists to add safety margins on the penetration depth of the beam. To reduce these margins and deliver safer treatments, different projects are currently investigating real-time range control by imaging prompt gammas emitted along the proton tracks in the patient. This study reports on the feasibility, development and test of a new concept of prompt gamma camera using a slit collimator to obtain a one-dimensional projection of the beam path on a scintillation detector. This concept was optimized, using the Monte Carlo code MCNPX version 2.5.0, to select high energy photons correlated with the beam range and detect them with both high statistics and sufficient spatial resolution. To validate the Monte Carlo model, spectrometry measurements of secondary particles emitted by a PMMA target during proton irradiation at 160 MeV were realized. An excellent agreement with the simulations was observed when using subtraction methods to isolate the gammas in direct incidence. A first prototype slit camera using the HiCam gamma detector was consequently prepared and tested successfully at 100 and 160 MeV beam energies. Results confirmed the potential of this concept for real-time range monitoring with millimetre accuracy in pencil beam scanning mode for typical clinical conditions. If we neglect electronic dead times and rejection of detected events, the current solution with its collimator at 15 cm from the beam axis can achieve a 1-2 mm standard deviation on range estimation in a homogeneous PMMA target for numbers of protons that correspond to doses in water at the Bragg peak as low as 15 cGy at 100 MeV and 25 cGy at 160 MeV assuming pencil beams with a Gaussian profile of 5 mm sigma at target entrance.

  19. Physical characterization of a scanning photon counting digital mammography system based on Si-strip detectors

    SciTech Connect

    Aaslund, Magnus; Cederstroem, Bjoern; Lundqvist, Mats; Danielsson, Mats

    2007-06-15

    The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge-on geometry connected to photon counting electronics. The pixel size is 50 {mu}m and the field of view 24x26 cm{sup 2}. The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the 7.6-206 {mu}Gy range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a 28 kV W-0.5 mm Al anode-filter combination with an added 2 mm Al filtration.

  20. Precision optical slit for high heat load or ultra high vacuum

    DOEpatents

    Andresen, N.C.; DiGennaro, R.S.; Swain, T.L.

    1995-01-24

    This invention relates generally to slits used in optics that must be precisely aligned and adjusted. The optical slits of the present invention are useful in x-ray optics, x-ray beam lines, optical systems in which the entrance slit is critical for high wavelength resolution. The invention is particularly useful in ultra high vacuum systems where lubricants are difficult to use and designs which avoid the movement of metal parts against one another are important, such as monochromators for high wavelength resolution with ultra high vacuum systems. The invention further relates to optical systems in which temperature characteristics of the slit materials is important. The present invention yet additionally relates to precision slits wherein the opposing edges of the slit must be precisely moved relative to a center line between the edges with each edge retaining its parallel orientation with respect to the other edge and/or the center line. 21 figures.

  1. Precision optical slit for high heat load or ultra high vacuum

    DOEpatents

    Andresen, Nord C.; DiGennaro, Richard S.; Swain, Thomas L.

    1995-01-01

    This invention relates generally to slits used in optics that must be precisely aligned and adjusted. The optical slits of the present invention are useful in x-ray optics, x-ray beam lines, optical systems in which the entrance slit is critical for high wavelength resolution. The invention is particularly useful in ultra high vacuum systems where lubricants are difficult to use and designs which avoid the movement of metal parts against one another are important, such as monochrometers for high wavelength resolution with ultra high vacuum systems. The invention further relates to optical systems in which temperature characteristics of the slit materials is important. The present invention yet additionally relates to precision slits wherein the opposing edges of the slit must be precisely moved relative to a center line between the edges with each edge retaining its parallel orientation with respect to the other edge and/or the center line.

  2. Star scanner. [with a reticle with a pair of slits having differing separation

    NASA Technical Reports Server (NTRS)

    Gutshall, R. L.; Mcconaughey, R. T.; Volpe, F. A. (Inventor)

    1974-01-01

    A star scanner on a spin stabilized spacecraft is described which includes a reticle with a pair of slits having different separations as a function of the spacecraft vertical plane, to form a V slit. The time between a star image crossing one of the slits relative to a reference telemetry time provides an indication of azimuth angle. The time between the image crossing the two slits provides an indication of elevation angle of the star. If a star cluster is detected such that two stars pass the slits in less time than normally required for a single star to cross the two slits, an indication of the cluster occurrence is derived. Means are provided to prevent effective detection of large celestial bodies, such as the sun or moon.

  3. Ring polymer chains confined in a slit geometry of two parallel walls: the massive field theory approach

    NASA Astrophysics Data System (ADS)

    Usatenko, Z.; Halun, J.

    2017-01-01

    The investigation of a dilute solution of phantom ideal ring polymer chains confined in a slit geometry of two parallel repulsive walls, two inert walls, and for the mixed case of one inert and the other one repulsive wall, was performed. Taking into account the well known correspondence between the field theoretical {φ4} O(n)-vector model in the limit n\\to 0 and the behaviour of long-flexible polymer chains in a good solvent, the investigation of a dilute solution of long-flexible ring polymer chains with the excluded volume interaction (EVI) confined in a slit geometry of two parallel repulsive walls was performed in the framework of the massive field theory approach at fixed space dimensions d  =  3 up to one-loop order. For all the above mentioned cases, the correspondent depletion interaction potentials, the depletion forces and the forces which exert the phantom ideal ring polymers and the ring polymers with the EVI on the walls were calculated, respectively. The obtained results indicate that the phantom ideal ring polymer chains and the ring polymer chains with the EVI due to the complexity of chain topology and because of the entropical reason demonstrate completely different behaviour in confined geometries than linear polymer chains. For example, the phantom ideal ring polymers prefer to escape from the space not only between two repulsive walls but also in the case of two inert walls, which leads to the attractive depletion forces. The ring polymer chains with less complex knot types (with the bigger radius of gyration) in a ring topology in the wide slit region exert higher forces on the confining repulsive walls. The depletion force in the case of mixed boundary conditions becomes repulsive in contrast to the case of linear polymer chains.

  4. [Purkinje images in slit lamp videography : Video article].

    PubMed

    Gellrich, M-M; Kandzia, C

    2016-09-01

    Reflexes that accompany every examination with the slit lamp are usually regarded as annoying and therefore do not receive much attention. In the video available online, clinical information "hidden" in the Purkinje images is analyzed according to our concept of slit lamp videography. In the first part of the video, the four Purkinje images which are reflections on the eye's optical surfaces are introduced for the phakic eye. In the pseudophakic eye, however, the refracting surfaces of the intraocular lens (IOL) have excellent optical properties and therefore form Purkinje images 3 and 4 of high quality. Especially the third Purkinje image from the anterior IOL surface, which is usually hardly visible in the phakic eye can be detected deep in the vitreous, enlarged through the eye's own optics like a magnifying glass. Its area of reflection can be used to visualize changes of the anterior segment at high contrast. The third Purkinje image carries valuable information about the anterior curvature and, thus, about the power of the IOL. If the same IOL type is implanted in a patient, often a difference between right and left of 0.5 diopter in its power can be detected by the difference in size of the respective third Purkinje image. In a historical excursion to the "prenatal phase" of the slit lamp in Uppsala, we show that our most important instrument in clinical work was originally designed for catoptric investigations (of specular reflections). Accordingly A. Gullstrand called it an ophthalmometric Nernst lamp.

  5. Sublingual (SLIT) versus oral immunotherapy (OIT) for food allergy.

    PubMed

    McGowan, Emily C; Wood, Robert A

    2014-12-01

    Food allergy is a common condition for which the only currently approved treatments are avoidance of the allergenic food and the administration of emergency medications upon accidental exposure. Over the past 10 years, significant advances have been made in the field of food immunotherapy, with efforts focusing on allergen exposure via the oral mucosa. Oral immunotherapy (OIT) and sublingual immunotherapy (SLIT) are the two modalities that have been most extensively studied, and this article will review recent advances in our knowledge of the efficacy and safety of these treatments.

  6. Sublingual (SLIT) Versus Oral Immunotherapy (OIT) for Food Allergy

    PubMed Central

    McGowan, Emily C.

    2016-01-01

    Food allergy is a common condition for which the only currently approved treatments are avoidance of the allergenic food and the administration of emergency medications upon accidental exposure. Over the past 10 years, significant advances have been made in the field of food immunotherapy, with efforts focusing on allergen exposure via the oral mucosa. Oral immunotherapy (OIT) and sublingual immunotherapy (SLIT) are the two modalities that have been most extensively studied, and this article will review recent advances in our knowledge of the efficacy and safety of these treatments. PMID:25297805

  7. Momentum slits, collimators and masks in the SLC

    SciTech Connect

    Walz, D.R.; McFarlane, A.; Lewandowski, E.; Zabdyr, J.

    1989-04-01

    The high specific power densities in the SLC give rise to a multitude of challenging problems in collimation and momentum analysis, beam containment, machine protection and background control. The results of an extensive program to develop most of the devices deemed necessary for operation of the arcs matching sections and the final focus region are presented. Emphasis is placed on materials selection and on unique features of remotely adjustable slits and halo clipper collimators which have to operate with great precision in a high-radiation, ultra-high vacuum environment. Also covered are solutions for a few fixed aperture machine protection collimators. 7 refs., 5 figs.

  8. Electron capture acceleration channel in a slit laser beam

    SciTech Connect

    Wang, P. X.; Scheid, W.; Ho, Y. K.

    2007-03-12

    Using numerical simulations, the authors find that the electrons can be captured and accelerated to high energies (GeV) in a slit laser beam with an intensity of I{lambda}{sup 2}{approx}10{sup 20} W/cm{sup 2} {mu}m{sup 2}, where {lambda} is the laser wavelength in units of {mu}m. The range of the optimum incident energy is very wide, even up to GeV. These results are of interest for experiments because the relatively low intensity can be achieved with present chirped pulse amplification technique and a wide range of incident energies means that a multistage acceleration is possible.

  9. Digital spiral-slit for bi-photon imaging

    NASA Astrophysics Data System (ADS)

    McLaren, Melanie; Forbes, Andrew

    2017-04-01

    Quantum ghost imaging using entangled photon pairs has become a popular field of investigation, highlighting the quantum correlation between the photon pairs. We introduce a technique using spatial light modulators encoded with digital holograms to recover both the amplitude and the phase of the digital object. Down-converted photon pairs are entangled in the orbital angular momentum basis, and are commonly measured using spiral phase holograms. Consequently, by encoding a spiral ring-slit hologram into the idler arm, and varying it radially we can simultaneously recover the phase and amplitude of the object in question. We demonstrate that a good correlation between the encoded field function and the reconstructed images exists.

  10. Critical discharge of initially subcooled water through slits. [PWR; BWR

    SciTech Connect

    Amos, C N; Schrock, V E

    1983-09-01

    This report describes an experimental investigation into the critical flow of initially subcooled water through rectangular slits. The study of such flows is relevant to the prediction of leak flow rates from cracks in piping, or pressure vessels, which contain sufficient enthalpy that vaporization will occur if they are allowed to expand to the ambient pressure. Two new analytical models, which allow for the generation of a metastable liquid phase, are developed. Experimental results are compared with the predictions of both these new models and with a Fanno Homogeneous Equilibrium Model.

  11. Involvement of the SLIT/ROBO pathway in follicle development in the fetal ovary.

    PubMed

    Dickinson, Rachel E; Hryhorskyj, Lynn; Tremewan, Hannah; Hogg, Kirsten; Thomson, Axel A; McNeilly, Alan S; Duncan, W Colin

    2010-02-01

    In humans and domestic mammals, pivotal processes in ovary development, including primordial follicle assembly, occur prenatally. These events are essential for determining fertility in adult life; however, they remain poorly understood at the mechanistic level. In mammals, the SLITs (SLIT1, SLIT2 and SLIT3) and their ROBO (ROBO1, ROBO2, ROBO3/RIG-1 and ROBO4/MAGIC ROBO) receptors regulate neural, leukocyte, vascular smooth muscle cell and endothelial cell migration. In addition, the SLIT/ROBO pathway has functional roles in embryonic development and in the adult ovary by inhibiting cell migration and promoting apoptosis. We therefore characterised follicle formation and investigated the expression and localisation of the ROBO/SLIT pathway in the ovine fetal ovary. Using RT-PCR, we identified SLIT2, SLIT3, ROBO1, ROBO2 and ROBO4 in sheep ovaries harvested across gestation. The real-time quantitative PCR results implied that ROBO2 expression and ROBO4 expression were elevated during the early stages of follicle formation and stayed abundant during primordial follicle maturation (P<0.05). Immunohistochemistry examination demonstrated that ROBO1 was localised to the pre-granulosa cells, while ROBO2, ROBO4 and SLIT2 were expressed in the oocytes of the developing primordial follicle. This indicates that in the fetal ovary, SLIT-ROBO signalling may require an autocrine and paracrine interaction. Furthermore, at the time of increased SLIT-ROBO expression, there was a significant reduction in the number of proliferating oocytes in the developing ovary (P<0.0001). Overall, these results suggest, for the first time, that the SLIT-ROBO pathway is expressed at the time of follicle formation during fetal ovary development.

  12. [Development of slit-lamp microscope and its applications in optics].

    PubMed

    Qi, Haohui

    2013-11-01

    This paper mainly introduces the origin and development of the slit-lamp microscope, the basic structure, working principle and test methods, focuses on diffuse illumination, direct focal illumination, indirect illumination, retro illumination, zone of specular reflection and slit-lamp filter used in the optical inspection, to provide the reference for clinical general optometry practitioners and using slit-lamp microscope widely and standardized.

  13. Thyroid scan

    MedlinePlus

    ... rays given off by the radioactive material. A computer displays images of the thyroid gland. Other scans ... It is an even gray color on the computer image without darker or lighter areas. What Abnormal ...

  14. Gallium scan

    MedlinePlus

    ... material called gallium and is a type of nuclear medicine exam. A related test is gallium scan ... Brown ML, Forstrom LA, et al. Society of nuclear medicine procedure guideline for gallium scintigraphy in inflammation. ...

  15. Liver scan

    MedlinePlus

    ... cirrhosis or hepatitis ) Superior vena cava obstruction Splenic infarction (tissue death) Tumors Risks Radiation from any scan ... Hepatitis Liver cancer - hepatocellular carcinoma Liver disease Splenic infarction SVC obstruction Review Date 1/18/2015 Updated ...

  16. Fraunhofer diffraction of light with orbital angular momentum by a slit.

    PubMed

    Ferreira, Queila S; Jesus-Silva, Alcenísio J; Fonseca, Eduardo J S; Hickmann, Jandir M

    2011-08-15

    We study the Fraunhofer diffraction problem while taking into account the orbital angular momentum of light. In this case, the phase singularity of the light beam is incident on the slit in two different cases: in one, it is incident slightly above the slit, and in the other it is centered on the slit. We observed that the symmetry and the fringe formation in the interference pattern strongly depend on the amount of orbital angular momentum and the slit position in relation to the beam.

  17. [Advance studies of Slit-Robo signal pathway and its roles in ocular neovascularisation].

    PubMed

    Kong, Yichun; Zhao, Kanxing

    2014-05-01

    The migration and patterning of axons and blood vessels share similar guidance mechanisms. Slits and their Roundabout (Robo) receptors were initially characterized as repulsive guidance cues for neuronal axons and mediate the migration of neuronal precursor cells during neural development. In recent years, the research of Slit/Robo signal pathway on neovascularization has become one of hot topics. This review will focus on the role of Slit/Robo signal pathway in ocular neovascularization to promote the research of Slit/Robo signaling on ophthalmology.

  18. Numerical simulation of a single cell passing through a narrow slit

    PubMed Central

    Xiao, L. L.; Liu, Y.; Chen, S.; Fu, B. M.

    2016-01-01

    The narrow slit between endothelial cells that line the microvessel wall is the principal pathway for tumor cell extravasation to the surrounding tissue. To understand this crucial step for tumor hematogenous metastasis, we used dissipative particle dynamics method to investigate an individual cell passing through a narrow slit numerically. The cell membrane was simulated by a spring-based network model which can separate the internal cytoplasm and surrounding fluid. The effects of the cell elasticity, cell shape, nucleus and slit size on the cell transmigration through the slit were investigated. Under a fixed driving force, the cell with higher elasticity can be elongated more and pass faster through the slit. When the slit width decreases to 2/3 of the cell diameter, the spherical cell becomes jammed despite reducing its elasticity modulus by 10 times. However, transforming the cell from a spherical to ellipsoidal shape and increasing the cell surface area by merely 9.3% can enable the cell to pass through the narrow slit. Therefore, the cell shape and surface area increase play a more important role than the cell elasticity in cell passing through the narrow slit. In addition, the simulation results indicate that the cell migration velocity decreases during entrance but increases during exit of the slit, which is qualitatively in agreement with the experimental observation. PMID:27080221

  19. Maximal Expression of the Evolutionarily Conserved Slit2 Gene Promoter Requires Sp1

    PubMed Central

    Saunders, Jacquelyn; Wisidagama, D. Roonalika; Morford, Travis; Malone, Cindy S.

    2015-01-01

    Slit2 is a neural axon guidance and chemorepellent protein that stimulates motility in a variety of cell types. The role of Slit2 in neural development and neoplastic growth and migration has been well established, while the genetic mechanisms underlying regulation of the Slit2 gene have not. We identified the core and proximal promoter of Slit2 by mapping multiple transcriptional start sites, analyzing transcriptional activity, and confirming sequence homology for the Slit2 proximal promoter among a number of species. Deletion series and transient transfection identified the Slit2 proximal promoter as within 399 base pairs upstream of the start of transcription. A crucial region for full expression of the Slit2 proximal promoter lies between 399 base pairs and 296 base pairs upstream of the start of transcription. Computer modeling identified three transcription factor binding consensus sites within this region, of which only site-directed mutagenesis of one of the two identified Sp1 consensus sites inhibited transcriptional activity of the Slit2 proximal promoter (−399 to +253). Bioinformatics analysis of the Slit2 proximal promoter −399 base pair to −296 base pair region shows high sequence conservation over twenty-two species, and that this region follows an expected pattern of sequence divergence through evolution. PMID:26456684

  20. A novel multi slit X-ray backscatter camera based on synthetic aperture focusing

    NASA Astrophysics Data System (ADS)

    Wieder, Frank; Ewert, Uwe; Vogel, Justus; Jaenisch, Gerd-Rüdiger; Bellon, Carsten

    2017-02-01

    A special slit collimator was developed earlier for fast acquisition of X-ray back scatter images. The design was based on a twisted slit design (ruled surfaces) in a Tungsten block to acquire backscatter images. The comparison with alternative techniques as flying spot and coded aperture pin hole technique could not prove the expected higher contrast sensitivity. In analogy to the coded aperture technique, a novel multi slit camera was designed and tested. Several twisted slits were parallelly arranged in a metal block. The CAD design of different multi-slit cameras was evaluated and optimized by the computer simulation packages aRTist and McRay. The camera projects a set of equal images, one per slit, to the digital detector array, which are overlaying each other. Afterwards, the aperture is corrected based on a deconvolution algorithm to focus the overlaying projections into a single representation of the object. Furthermore, a correction of the geometrical distortions due to the slit geometry is performed. The expected increase of the contrast-to-noise ratio is proportional to the square root of the number of parallel slits in the camera. However, additional noise has to be considered originating from the deconvolution operation. The slit design, functional principle, and the expected limits of this technique are discussed.

  1. The SLIT/ROBO pathway: a regulator of cell function with implications for the reproductive system

    PubMed Central

    Dickinson, Rachel E; Duncan, W Colin

    2010-01-01

    The secreted SLIT glycoproteins and their Roundabout (ROBO) receptors were originally identified as important axon guidance molecules. They function as a repulsive cue with an evolutionarily conserved role in preventing axons from migrating to inappropriate locations during the assembly of the nervous system. In addition the SLIT-ROBO interaction is involved in the regulation of cell migration, cell death and angiogenesis and, as such, has a pivotal role during the development of other tissues such as the lung, kidney, liver and breast. The cellular functions that the SLIT/ROBO pathway controls during tissue morphogenesis are processes that are dysregulated during cancer development. Therefore inactivation of certain SLITs and ROBOs is associated with advanced tumour formation and progression in disparate tissues. Recent research has indicated that the SLIT/ROBO pathway could also have important functions in the reproductive system. The fetal ovary expresses most members of the SLIT and ROBO families. The SLITs and ROBOs also appear to be regulated by steroid hormones and regulate physiological cell functions in adult reproductive tissues such as the ovary and endometrium. Furthermore several SLITs and ROBOs are aberrantly expressed during the development of ovarian, endometrial, cervical and prostate cancer. This review will examine the roles this pathway could have in the development, physiology and pathology of the reproductive system and highlight areas for future research that could further dissect the influence of the SLIT/ROBO pathway in reproduction. PMID:20100881

  2. The SLIT-ROBO pathway: a regulator of cell function with implications for the reproductive system.

    PubMed

    Dickinson, Rachel E; Duncan, W Colin

    2010-04-01

    The secreted SLIT glycoproteins and their Roundabout (ROBO) receptors were originally identified as important axon guidance molecules. They function as a repulsive cue with an evolutionarily conserved role in preventing axons from migrating to inappropriate locations during the assembly of the nervous system. In addition the SLIT-ROBO interaction is involved in the regulation of cell migration, cell death and angiogenesis and, as such, has a pivotal role during the development of other tissues such as the lung, kidney, liver and breast. The cellular functions that the SLIT/ROBO pathway controls during tissue morphogenesis are processes that are dysregulated during cancer development. Therefore inactivation of certain SLITs and ROBOs is associated with advanced tumour formation and progression in disparate tissues. Recent research has indicated that the SLIT/ROBO pathway could also have important functions in the reproductive system. The fetal ovary expresses most members of the SLIT and ROBO families. The SLITs and ROBOs also appear to be regulated by steroid hormones and regulate physiological cell functions in adult reproductive tissues such as the ovary and endometrium. Furthermore several SLITs and ROBOs are aberrantly expressed during the development of ovarian, endometrial, cervical and prostate cancer. This review will examine the roles this pathway could have in the development, physiology and pathology of the reproductive system and highlight areas for future research that could further dissect the influence of the SLIT/ROBO pathway in reproduction.

  3. Surface plasmon polariton analogue to Young's double-slit experiment.

    PubMed

    Zia, Rashid; Brongersma, Mark L

    2007-07-01

    When a light wave strikes a metal film it can, under appropriate conditions, excite a surface plasmon polariton (SPP)--a surface electromagnetic wave that is coupled to the free electrons in the metal. Such SPPs are involved in a wide range of phenomena, including nanoscale optical waveguiding, perfect lensing, extraordinary optical transmission, subwavelength lithography and ultrahigh-sensitivity biosensing. However, before the full potential of technology based on SPPs (termed 'plasmonics') can be realized, many fundamental questions regarding the interaction between light and matter at the nanoscale need to be answered. For over 200 years, Young's double-slit experiment has been a valuable pedagogical tool for demonstrating the wave nature of light. Here, we perform a double-slit experiment with SPPs to reveal the strong analogy between SPP propagation along the surface of metallic structures and light propagation in conventional dielectric components (such as glass waveguides). This allows us to construct a general framework to describe the propagation, diffraction and interference of SPPs. It also suggests that there is an effective diffraction limit for the lateral confinement of SPPs on metal stripe waveguides, and justifies the use of well-developed concepts from conventional optics and photonics in the design of new plasmonic devices.

  4. Adaptive SPECT imaging with crossed-slit apertures

    NASA Astrophysics Data System (ADS)

    Durko, Heather L.; Furenlid, Lars R.

    2014-09-01

    Preclinical single-photon emission computed tomography (SPECT) is an essential tool for studying the pro-gression, response to treatment, and physiological changes in small animal models of human disease. The wide range of imaging applications is often limited by the static design of many preclinical SPECT systems. We have developed a prototype imaging system that replaces the standard static pinhole aperture with two sets of movable, keel-edged copper-tungsten blades configured as crossed (skewed) slits. These apertures can be positioned independently between the object and detector, producing a continuum of imaging configurations in which the axial and transaxial magnifications are not constrained to be equal. We incorporated a megapixel silicon double-sided strip detector to permit ultrahigh-resolution imaging. We describe the configuration of the adjustable slit aperture imaging system and discuss its application toward adaptive imaging, and reconstruction techniques using an accurate imaging forward model, a novel geometric calibration technique, and a GPU-based ultra-high-resolution reconstruction code.

  5. Diffraction of Gaussian wave packets by a single slit

    NASA Astrophysics Data System (ADS)

    Zecca, A.

    2011-02-01

    A two-dimensional formulation of particle diffraction by a single slit is proposed within Schrödinger QM. The study is done in terms of Gaussian wave packets. A "confinement" assumption is considered together with a previous "truncation" assumption when the wave packet passes the slit. In the limiting situation of entering Gaussian wave packet peaked in the transverse-momentum probability distribution, the diffraction pattern results in an unaltered central maximum with lateral maxima narrower and higher than in the absence of the confinement assumption. For entering wave packets peaked in the transverse position probability distribution, the diffraction pattern consists of a central Gaussian spot with lateral diffraction maxima, not present in the absence of the "confinement" assumption, whose visibility depends on the configuration of the parameters. With a different analysis, a similar effect was obtained also in G. Kalbermann (J. Phys. A: Math. Gen. 35, 4599 (2002)). Its experimental verification seems of interest to discriminate between Schrödinger QM and stochastic electrodynamics with spin.

  6. Slit2-Robo signaling in inflammation and kidney injury.

    PubMed

    Chaturvedi, Swasti; Robinson, Lisa A

    2015-04-01

    Acute kidney injury is an increasingly common global health problem and is associated with severe morbidity and mortality. In addition to facing high mortality rates, the survivors of acute kidney injury are at increased risk of developing chronic kidney disease and end-stage renal disease. Renal ischemia-reperfusion injury (IRI) is the most common cause of acute kidney injury, and results from impaired delivery of oxygen and nutrients to the kidney. Massive leukocyte influx into the post-ischemic kidney is one of the hallmarks of IRI. The recruited leukocytes exacerbate tissue damage and, if uncontrolled, initiate the progressive changes that lead to renal fibrosis and chronic kidney disease. Early on, recruitment and activation of platelets promotes microthrombosis in the injured kidney, further exacerbating kidney damage. The diversity, complexity, and multiplicity of pathways involved in leukocyte recruitment and platelet activation make it extremely challenging to control these processes, and past efforts have met with limited success in human trials. A generalized strategy to inhibit infiltration of inflammatory leukocytes and platelets, thereby reducing inflammation and injury, may prove to be more beneficial. In this review, we summarize recent findings demonstrating that the neuronal guidance cues, Slit and Roundabout (Robo), prevent the migration of multiple leukocyte subsets towards diverse inflammatory chemoattractants, and have potent anti-platelet functions in vitro and in vivo. These properties uniquely position Slit2 as a novel therapeutic that could be used to prevent acute kidney injury associated with IRI.

  7. Dynamics of Red Blood Cells through submicronic splenic slits

    NASA Astrophysics Data System (ADS)

    Helfer, Emmanuele; Gambhire, Priya; Atwell, Scott; Bedu, Frederic; Ozerov, Igor; Viallat, Annie; Charrier, Anne; Badens, Catherine; Centre de reference Thalassemie, Badens Team; Physics; Engineering of Living Systems Team

    2016-11-01

    Red Blood Cells (RBCs) are periodically monitored for changes in their deformability by the spleen, and are entrapped and destroyed if unable to pass through the splenic interendothelial slits (IESs). In particular, in sickle cell disease (SCD), where hemoglobin form fibers inside the RBCs, and in hereditary spherocytosis (HS), where RBCs are more spherical and membrane-cytoskekeleton bonds are weakened, the loss of RBC deformability leads to spleen dysfunction. By combining photolithography and anisotropic wet etching techniques, we developed a new on-chip PDMS device with channels replicating the submicronic physiological dimensions of IESs to study the mechanisms of deformation of the RBCs during their passage through these biomimetic slits. For the first time, with HS RBCs, we show the disruption of the links between the RBC membrane and the underlying spectrin network. In the case of SCD RBCs we show the appearance of a tip at the front of the RBC with a longer time relaxation due to the increased cytoplasmic viscosity. This work has been carried out thanks to the support of the A*MIDEX project (n° ANR-11-IDEX-0001-02) funded by the «Investissements d'Avenir». French Government program, managed by ANR.

  8. Adaptive SPECT imaging with crossed-slit apertures

    PubMed Central

    Durko, Heather L.; Furenlid, Lars R.

    2015-01-01

    Preclinical single-photon emission computed tomography (SPECT) is an essential tool for studying the progression, response to treatment, and physiological changes in small animal models of human disease. The wide range of imaging applications is often limited by the static design of many preclinical SPECT systems. We have developed a prototype imaging system that replaces the standard static pinhole aperture with two sets of movable, keel-edged copper-tungsten blades configured as crossed (skewed) slits. These apertures can be positioned independently between the object and detector, producing a continuum of imaging configurations in which the axial and transaxial magnifications are not constrained to be equal. We incorporated a megapixel silicon double-sided strip detector to permit ultrahigh-resolution imaging. We describe the configuration of the adjustable slit aperture imaging system and discuss its application toward adaptive imaging, and reconstruction techniques using an accurate imaging forward model, a novel geometric calibration technique, and a GPU-based ultra-high-resolution reconstruction code. PMID:26190884

  9. A new fiber slit assembly for the FOCES spectrograph

    NASA Astrophysics Data System (ADS)

    Kellermann, Hanna; Grupp, Frank; Brucalassi, Anna; Lang-Bardl, Florian; Franik, Christian; Hopp, Ulrich; Bender, Ralf

    2015-09-01

    After successful operation at the Calar Alto telescope until 2009, and extensive lab tests at the Munich University Observatory the high resolution Échelle spectrograph FOCES (Fiber Optics Cassegrain Échelle Spectrograph) is now about to be reinstalled at the 2 m Wendelstein Observatory in the German Alps. For this new phase of operation FOCES will be equipped with new components that will improve time stability and wavelength calibration. With these modifications FOCES will meet the requirements for performing precision radial velocity measurements on a competitive level. One of the key features of the upgraded spectrograph is the new calibration system, which uses a laser frequency comb as reference light source. Another aspect is the possibility to perform simultaneous wavelength calibration, while recording science data. For this purpose a new 4-fiber slit has been developed, which opens up the possibility to feed light from different sources at the same time through the entrance slit of the spectrograph. We present a detailed characterization of this new device, based on the results of extensive lab tests performed at the Munich University Observatory.

  10. Superfocusing the light through the nanosize slit via photonic tornado

    NASA Astrophysics Data System (ADS)

    Choi, Seong Soo; Jha, Vinaya; Suwal, Om; Park, Myoung Jin; Park, Nam Kyu; Kim, Daisik

    2010-03-01

    The macro size pyramidal horn probe such as klystron horn antenna has been used to provide the excellent focusing capabilities in microwave region. In the similar way, the pyramidal probe with the micron size mirror (pyramidal horn probe) has been fabricated with a nano-size aperture with diameter ranging from ˜1 nm to ˜30 nm. Light transmission through the micro-fabricated pyramidal horn probe has been measured to enhance the light transmission due to resonant effects between the cavity mode and the slit modes in the probe, along with improved directionality of the transmitted beam. The resonant tunneling between two standing waves in the input groove and in the output groove can provide the transmission enhancements. With decreasing slit width, the transmission is found to increasing tremendously.[1] The transmission is measured to be inversely proportional to the area.[2,3] References:[1] R. Gordon, Phys. Rev. B 73, 153405 (2006).[2] R. Harrington, IEEE Trans. Antennas Propagat. Ap-30, 205(1982).[3] Y Leviatan, R. Harrington, J. Maut, IEEE Trans. Antennas Propagat. Ap-30, 1533(1982)

  11. Podocin localizes in the kidney to the slit diaphragm area.

    PubMed

    Roselli, Séverine; Gribouval, Olivier; Boute, Nicolas; Sich, Mireille; Benessy, France; Attié, Tania; Gubler, Marie-Claire; Antignac, Corinne

    2002-01-01

    We recently cloned a novel gene, NPHS2, involved in autosomal recessive steroid-resistant nephrotic syndrome. This gene encodes a novel podocyte protein, podocin. Given its similarity with the stomatin family proteins, podocin is predicted to be an integral membrane protein with a single membrane domain forming a hairpin-like structure placing both N- and C-termini in the cytosol. Here, we show by in situ hybridization, that during development, the NPHS2 transcript is first expressed in mesonephric podocytes from the S-shaped body and, later, in the metanephric kidney, in the future podocytes at the late S-shaped body stage. In the mature kidney, NPHS2 is exclusively expressed in the podocytes of mature glomeruli. We generated rabbit polyclonal antibodies against fusion proteins derived from the N- and the C-terminal regions of podocin which detected a single band of 49-kd in transfected HEK293 cell lysates by immunoprecipitation and Western blotting. By immunohistology, podocin was detected in podocytes from the early capillary loop stage in the developing nephrons, and at the basal pole, along the GBM, in mature glomeruli. By electron microscopy, we demonstrate that podocin is facing the slit diaphragm with its two ends in the cytoplasm of the foot processes, in agreement with its predicted structure. Our results suggest that podocin could serve to anchor directly or indirectly components of the slit diaphragm to the cytoskeleton.

  12. High resolution hyperspectral imaging with a high throughput virtual slit

    NASA Astrophysics Data System (ADS)

    Gooding, Edward A.; Gunn, Thomas; Cenko, Andrew T.; Hajian, Arsen R.

    2016-05-01

    Hyperspectral imaging (HSI) device users often require both high spectral resolution, on the order of 1 nm, and high light-gathering power. A wide entrance slit assures reasonable étendue but degrades spectral resolution. Spectrometers built using High Throughput Virtual Slit™ (HTVS) technology optimize both parameters simultaneously. Two remote sensing use cases that require high spectral resolution are discussed. First, detection of atmospheric gases with intrinsically narrow absorption lines, such as hydrocarbon vapors or combustion exhaust gases such as NOx and CO2. Detecting exhaust gas species with high precision has become increasingly important in the light of recent events in the automobile industry. Second, distinguishing reflected daylight from emission spectra in the visible and NIR (VNIR) regions is most easily accomplished using the Fraunhofer absorption lines in solar spectra. While ground reflectance spectral features in the VNIR are generally quite broad, the Fraunhofer lines are narrow and provide a signature of intrinsic vs. extrinsic illumination. The High Throughput Virtual Slit enables higher spectral resolution than is achievable with conventional spectrometers by manipulating the beam profile in pupil space. By reshaping the instrument pupil with reflective optics, HTVS-equipped instruments create a tall, narrow image profile at the exit focal plane, typically delivering 5X or better the spectral resolution achievable with a conventional design.

  13. Chaos and the two-slit experiment in metamaterial billiards

    NASA Astrophysics Data System (ADS)

    Litchinitser, Natalia M.; Jose, Jorge V.

    2013-03-01

    The two-slit experiment has played in important role in understanding the unintuitive properties in quantum mechanical solutions when compared to their corresponding classical ones. This configuration was analyzed in detail prior to the recognition that most classical mechanical systems are chaotic in nature. Some initial studies of the competition between interference and quantum chaos have appeared in the literature. Here we report theoretical and numerical results for a system which has an electromagnetic source confined inside chaotic billiards containing combinations of positive and negative index materials. Previously we predicted that such billiards support scar modes that can be controlled by tailoring dielectric permittivity and magnetic permeability of constituent materials. Here we consider the stability and interference properties of chaotic cavity solutions with different types of two-slit configurations when the index of refractions goes from positive to negative. In this talk, we discuss the evolution of interference patterns when the source is placed inside the metamaterials-based cavity and predict that the visibility of the interference fringes changes or completely disappear as a function of the geometry, the metamaterials' parameters and their spatial distribution. These metamaterial cavities show novel solutions that may have practical device applications.

  14. Human placental multipotent mesenchymal stromal cells modulate placenta angiogenesis through Slit2-Robo signaling.

    PubMed

    Chen, Cheng-Yi; Tsai, Chin-Han; Chen, Chia-Yu; Wu, Yi-Hsin; Chen, Chie-Pein

    2016-03-03

    The objective of this study was to investigate whether human placental multipotent mesenchymal stromal cell (hPMSC)-derived Slit2 and endothelial cell Roundabout (Robo) receptors are involved in placental angiogenesis. The hPMSC-conditioned medium and human umbilical vein endothelial cells were studied for Slit2 and Robo receptor expression by immunoassay and RT-PCR. The effect of the conditioned medium of hPMSCs with or without Slit2 depletion on endothelial cells was investigated by in vitro angiogenesis using growth factor-reduced Matrigel. hPMSCs express Slit2 and both Robo1 and Robo4 are present in human umbilical vein endothelial cells. Human umbilical vein endothelial cells do not express Robo2 and Robo3. The hPMSC-conditioned medium and Slit2 recombinant protein significantly inhibit the endothelial cell migration, but not by the hPMSC-conditioned medium with Slit2 depletion. The hPMSC-conditioned medium and Slit2 significantly enhance endothelial tube formation with increased cumulated tube length, polygonal network number and vessel branching point number compared to endothelial cells alone. The tube formation is inhibited by the depletion of Slit2 from the conditioned medium, or following the expression of Robo1, Robo4, and both receptor knockdown using small interfering RNA. Furthermore, co-immunoprecipitation reveals Slit2 binds to Robo1 and Robo4. Robo1 interacts and forms a heterodimeric complex with Robo4. These results suggest the implication of both Robo receptors with Slit2 signaling, which is involved in endothelial cell angiogenesis. Slit2 in the conditioned medium of hPMSCs has functional effect on endothelial cells and may play a role in placental angiogenesis.

  15. Targeting Slit-Roundabout signaling inhibits tumor angiogenesis in chemical-induced squamous cell carcinogenesis.

    PubMed

    Wang, Li-Jing; Zhao, Yuan; Han, Bing; Ma, Yu-Guang; Zhang, Jie; Yang, Ding-Ming; Mao, Jian-Wen; Tang, Fu-Tian; Li, Wei-Dong; Yang, Yang; Wang, Rui; Geng, Jian-Guo

    2008-03-01

    Slit is a secreted protein known to function through the Roundabout (Robo) receptor as a repellent for axon guidance and neuronal migration, and as an inhibitor in leukocyte chemotaxis. We have previously shown that Slit2 is also secreted by a variety of human cancer cells whereby it acts as a chemoattractant to vascular endothelial cells for tumor angiogenesis. We used a blocking antibody to investigate the role of Slit-Robo signaling in tumor angiogenesis during oral carcinogenesis. In this report we undertook a multistage model of 7,12-dimethyl-1,2-benzanthracene-induced squamous cell carcinoma in the hamster buccal pouch. R5, a monoclonal antibody against the first immunoglobulin domain of Robo1, was used to study whether R5 blocks the Slit-Robo interaction and furthermore inhibits tumor angiogenesis and growth in our model. In addition, the expression of Slit2, von Willebrand factor, and vascular endothelial growth factor were examined using human tissue of oral cheek mucosa with oral squamous cell carcinoma. Our data showed that Slit2 was expressed minimally in normal and hyperplastic mucosa, moderately in dysplastic mucosa, and highly in neoplastic mucosa obtained from hamster buccal pouch. We also found that increased Slit2 expression was associated with higher tumor angiogenesis, as reflected by increased vascular endothelial growth factor expression and microvessel density. A similar Slit2 expression profile was found in human tissue. Importantly, interruption of the Slit2-Robo interaction using R5 inhibited tumor angiogenesis and growth in our in vivo model, which indicates that Slit2-mediated tumor angiogenesis is a critical process underlying the carcinogenesis of chemical-induced squamous cell carcinoma. Therefore, targeting Slit-Robo signaling may offer a novel antiangiogenesis approach for oral cancer therapy.

  16. Slit2 is decreased after spontaneous labour in myometrium and regulates pro-labour mediators.

    PubMed

    Lim, Ratana; Liong, Stella; Barker, Gillian; Lappas, Martha

    2014-12-01

    Preterm birth, a global healthcare problem, is commonly associated with inflammation. As Slit2 plays an emerging role in inflammation, the purpose of this study was to determine the effect of Slit2 on labour mediators in human gestational tissues. Slit2 mRNA and protein expression were assessed using qRT-PCR and immunohistochemistry in foetal membranes and myometrium obtained before and after labour. Slit2 silencing was achieved using siRNA in primary myometrial cells. Pro-inflammatory and pro-labour mediators were evaluated by qRT-PCR, ELISA and gelatin zymography. Slit2 mRNA and protein expression were found to be significantly lower in myometrium after labour onset. There was no effect of term or preterm labour on Slit2 expression in foetal membranes. Slit2 mRNA expression was decreased in myometrium treated with LPS and IL-1β. Slit2 siRNA in myometrial cells increased IL-1β-induced pro-inflammatory cytokine gene expression and release (IL-6 and IL-8), COX-2 expression and prostaglandin PGE2 and PGF2α release, and MMP-9 gene expression and pro MMP-9 release. There was no effect of Slit2 siRNA on IL-1β-induced NF-κB transcriptional activity. Our results demonstrate that Slit2 is decreased in human myometrium after labour and our knock-down studies describe an anti-inflammatory effect of Slit2 in myometrial cells. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. UNREVIEWED DISPOSAL QUESTION EVALUATION: CENTER SLIT TRENCHES ONE THROUGH FIVE OPERATIONAL COVERS REANALYSIS

    SciTech Connect

    Smith, F.; Swingle, R.

    2011-05-26

    Operational inventory limits for the disposal of solid low-level waste in Slit Trenches 1-7 were established by the Special Analysis (SA) performed by Collard and Hamm (2008). To determine disposal limits for the Slit Trenches, the SA followed the methodology used in the 2008 PA (WSRC, 2008) which assumed that the inventories in each trench were instantaneously placed in 12/1995, which is the date when SLIT1 began operation. The 2008 SA analyzed the impact from placing storm-water runoff covers simultaneously over Slit Trenches 1-7 at 5, 10 and 15 years after the inventory was introduced. To include a measure of conservatism in the limits, the lowest of the limits calculated for any storm-water runoff cover placement time or that calculated in the original 2008 PA was chosen as the operational limit for each radionuclide. Through the availability of funding provided by the American Recovery and Reinvestment Act (ARRA), storm-water runoff covers were placed over Slit Trenches 1-5 in December 2010. SRNL was requested to perform a UDQE for this accelerated action. Table 1 below lists the operational dates for Slit Trenches 1-5 and the time elapsed between when the first waste package was disposed in each Slit Trench and when the storm-water runoff covers were placed. As shown in Table 1, SLIT1 was covered 15.0 years after the date of the first waste package disposal. SLIT2 was covered 9.2 years after the date of the first waste package disposal in SLIT2 which falls within the window of {+-} 1.0 year within which the 2008 SA cover time analysis was assumed to be valid (Crowley and Butcher, 2008). Therefore, the analysis of SLIT1 and SLIT2 in the 2008 SA is considered adequate. However, the cover timings for SLIT3, SLIT4 and SLIT5 are from 2.2 to 1.6 years beyond the nearest cover time of 5 years assumed in the 2008 SA analysis and fall outside of the acceptable one-year margin. Therefore, an additional study was conducted by Collard et al. (2011) that assessed the

  18. Combining freeform-shaped holographic grating and curved detectors in a scheme of multi-slit astronomic spectrograph

    NASA Astrophysics Data System (ADS)

    Muslimov, Eduard R.; Hugot, Emmanuel; Ferrari, Marc

    2017-05-01

    In the present work we consider optical design of a multi-slit astronomic spectrograph for UV domain with freeform reflective elements. The scheme consists of only two reflective elements - a holographic grating imposed on freeform surface and a freeform mirror. The freeforms are described by standard Zernike polynomials and the hologram is recorded by two coherent point sources. We demonstrate that in such a scheme it's possible to obtain quite high optical quality for an extended field of view and relatively high dispersion on a curved image surface. The spectrograph works with linear field of view of 76x32 mm and provides reciprocal linear dispersion equal to 0.5 nm/mm and typical resolving power of 15 000 over the UV range of 100-200 nm. Feasibility of the optical components is discussed and coupling of the spectrograph with a TMA telescope is demonstrated.

  19. Oil flow to a slit-like well in a reservoir containing other fluids

    NASA Astrophysics Data System (ADS)

    Emikh, V. N.

    2014-03-01

    An exact solution is obtained for the boundary-value problem of oil flow to a slit-like well in a reservoir containing other fluids adjacent to its top and base. This solution is used to compare the maximum possible oil production from slit-like and tubular wells in the double critical regime.

  20. Slit-2/Robo-1 modulates the CXCL12/CXCR4-induced chemotaxis of T cells.

    PubMed

    Prasad, Anil; Qamri, Zahida; Wu, Jane; Ganju, Ramesh K

    2007-09-01

    Slit, which mediates its function by binding to the Roundabout (Robo) receptor, has been shown to regulate neuronal, dendritic, and leukocyte migration. However, the molecular mechanism by which the Slit/Robo complex inhibits the migration of cells is not well defined. Here, we showed that Slit-2 can inhibit the CXCL12-induced chemotaxis and transendothelial migration of T cells and monocytes. We observed that CXCR4 associates with Robo-1 and that Slit-2 treatment enhances this association with the Robo-1 receptor. Robo-1 is a single-pass transmembrane receptor whose intracellular region contains four conserved motifs designated as CC0, CC1, CC2, and CC3. Structural and functional analyses of Robo receptors revealed that interaction of the CC3 motif with the CXCR4 receptor may regulate the CXCL12-induced chemotaxis of T cells. We further characterized Slit-2-mediated inhibition of the CXCL12/CXCR4 chemotactic pathway and found that Slit-2 can block the CXCL12-induced activation of the Src and Lck kinases but not Lyn kinase. Although Slit-2 did not inhibit the CXCL12-induced activation of MAPKs, it did inhibit the Akt phosphorylation and Rac activation induced by this chemokine. Altogether, our studies indicate a novel mechanism by which the Slit/Robo complex may inhibit the CXCR4/CXCL12-mediated chemotaxis of T cells.

  1. Prostaglandin F2α upregulates Slit/Robo expression in mouse corpus luteum during luteolysis.

    PubMed

    Zhang, Xuejing; Li, Jianhua; Liu, Jiali; Luo, Haoshu; Gou, Kemian; Cui, Sheng

    2013-09-01

    Prostaglandin F2 α (PGF2 α) is a key factor in the triggering of the regression of the corpus luteum (CL). Furthermore, it has been reported that Slit/Robo signaling is involved in the regulation of luteolysis. However, the interactions between PGF2 α and Slit/Robo in the progression of luteolysis remain to be established. This study was designed to determine whether luteolysis is regulated by the interactions of PGF2 α and Slit/Robo in the mouse CL. Real-time PCR and immunohistochemistry results showed that Slit2 and its receptor Robo1 are highly and specifically co-expressed in the mouse CL. Functional studies showed that Slit/Robo participates in mouse luteolysis by enhancing cell apoptosis and upregulating caspase3 expression. Both in vitro and in vivo studies showed that PGF2 α significantly increases the expression of Slit2 and Robo1 during luteolysis through protein kinase C-dependent ERK1/2 and P38 MAPK signaling pathways, whereas an inhibitor of Slit/Robo signaling significantly decreases the stimulating effect of PGF2 α on luteolysis. These findings indicate that Slit/Robo signaling plays important roles in PGF2 α-induced luteolysis by mediating the PGF2 α signaling pathway in the CL.

  2. Pioneer longitudinal axons navigate using floor plate and Slit/Robo signals.

    PubMed

    Farmer, W Todd; Altick, Amy L; Nural, Hikmet Feyza; Dugan, James P; Kidd, Thomas; Charron, Frédéric; Mastick, Grant S

    2008-11-01

    Longitudinal axons transmit all signals between the brain and spinal cord. Their axon tracts through the brain stem are established by a simple set of pioneer axons with precise trajectories parallel to the floor plate. To identify longitudinal guidance mechanisms in vivo, the overall role of floor plate tissue and the specific roles of Slit/Robo signals were tested. Ectopic induction or genetic deletion of the floor plate diverted longitudinal axons into abnormal trajectories. The expression patterns of the diffusible cues of the Slit family were altered in the floor plate experiments, suggesting their involvement in longitudinal guidance. Genetic tests of Slit1 and Slit2, and the Slit receptors Robo1 and Robo2 were carried out in mutant mice. Slit1;Slit2 double mutants had severe longitudinal errors, particularly for ventral axons, including midline crossing and wandering longitudinal trajectories. Robo1 and Robo2 were largely genetically redundant, and neither appeared to specify specific tract positions. However, combined Robo1 and Robo2 mutations strongly disrupted each pioneer tract. Thus, pioneer axons depend on long-range floor plate cues, with Slit/Robo signaling required for precise longitudinal trajectories.

  3. Recombinant N-Terminal Slit2 Inhibits TGF-β-Induced Fibroblast Activation and Renal Fibrosis.

    PubMed

    Yuen, Darren A; Huang, Yi-Wei; Liu, Guang-Ying; Patel, Sajedabanu; Fang, Fei; Zhou, Joyce; Thai, Kerri; Sidiqi, Ahmad; Szeto, Stephen G; Chan, Lauren; Lu, Mingliang; He, Xiaolin; John, Rohan; Gilbert, Richard E; Scholey, James W; Robinson, Lisa A

    2016-09-01

    Fibrosis and inflammation are closely intertwined injury pathways present in nearly all forms of CKD for which few safe and effective therapies exist. Slit glycoproteins signaling through Roundabout (Robo) receptors have been described to have anti-inflammatory effects through regulation of leukocyte cytoskeletal organization. Notably, cytoskeletal reorganization is also required for fibroblast responses to TGF-β Here, we examined whether Slit2 also controls TGF-β-induced renal fibrosis. In cultured renal fibroblasts, which we found to express Slit2 and Robo-1, the bioactive N-terminal fragment of Slit2 inhibited TGF-β-induced collagen synthesis, actin cytoskeletal reorganization, and Smad2/3 transcriptional activity, but the inactive C-terminal fragment of Slit2 did not. In mouse models of postischemic renal fibrosis and obstructive uropathy, treatment with N-terminal Slit2 before or after injury inhibited the development of renal fibrosis and preserved renal function, whereas the C-terminal Slit2 had no effect. Our data suggest that administration of recombinant Slit2 may be a new treatment strategy to arrest chronic injury progression after ischemic and obstructive renal insults by not only attenuating inflammation but also, directly inhibiting renal fibrosis. Copyright © 2016 by the American Society of Nephrology.

  4. Slit3 inhibits activator protein 1-mediated migration of malignant melanoma cells.

    PubMed

    Denk, Alexandra E; Braig, Simone; Schubert, Thomas; Bosserhoff, Anja K

    2011-11-01

    The repellent factor family of Slit molecules has been described to have repulsive function in the developing nervous system on growing axons expressing the Robo receptors. Alterations of the Slit/Robo system have been observed in various pathological conditions and in cancer. However, until today no detailed studies on Slit function on melanoma migration are available. Therefore, we analysed the mRNA expression in melanoma cells and found induction of Robo3 expression compared to normal melanocytes. Functional assays performed with melanoma cells revealed that treatment with Slit3 led to strong inhibition of migration. Interestingly, we observed down-regulation of AP-1 activity and target gene expression after Slit3 treatment contributing to the negative regulation of migration. Taken together, our data showed that Slit3 reduces the migratory activity of melanoma cells, potentially by repulsion of the cells in analogy to the neuronal system. Further studies will be necessary to prove Slit activity in vivo, but due to its function, Slit3 activity may be helpful in the treatment of melanoma.

  5. Slit-Surface Electrospinning: A Novel Process Developed for High-Throughput Fabrication of Core-Sheath Fibers

    PubMed Central

    Yan, Xuri; Marini, John; Mulligan, Robert; Deleault, Abby; Sharma, Upma; Brenner, Michael P.; Rutledge, Gregory C.; Freyman, Toby; Pham, Quynh P.

    2015-01-01

    In this work, we report on the development of slit-surface electrospinning – a process that co-localizes two solutions along a slit surface to spontaneously emit multiple core-sheath cone-jets at rates of up to 1 L/h. To the best of our knowledge, this is the first time that production of electrospun core-sheath fibers has been scaled to this magnitude. Fibers produced in this study were defect-free (i.e. non-beaded) and core-sheath geometry was visually confirmed under scanning electron microscopy. The versatility of our system was demonstrated by fabrication of (1) fibers encapsulating a drug, (2) bicomponent fibers, (3) hollow fibers, and (4) fibers from a polymer that is not normally electrospinnable. Additionally, we demonstrate control of the process by modulating parameters such as flow rate, solution viscosity, and fixture design. The technological achievements demonstrated in this work significantly advance core-sheath electrospinning towards commercial and manufacturing viability. PMID:25938411

  6. Super-transmission from a finite subwavelength arrangement of slits in a metal film.

    PubMed

    Chen, Shuwen; Jin, Shilong; Gordon, Reuven

    2014-06-02

    A theory is presented for the transmission of transverse magnetic waves through a finite number of subwavelength slits in metal film. While a single slit achieves the single channel limit on resonance, multiple slits show super-transmission exceeding the single channel limit. The phenomenon of super-transmission is revealed as a result of cross-coupling of modes and confirmed by simulations. The influence of finite permittivity in the IR and microwave regime is included by perturbative corrections to the theory. The theory agrees quantitatively with past experiments and finite-difference time-domain simulations. By considering two or more modes in the slit region, our theory provides an approach to the analysis of cross-coupling among slits, which allows for super-transmission and features of a Fano resonance.

  7. A New Metric For Triple-Slit Tests of Born's Rule

    NASA Astrophysics Data System (ADS)

    Nesselrodt, Ryan; Gagnon, Etienne; Lytle, Amy; Moreno, Justin

    2017-01-01

    Born's rule provides the critical link between theory and experiment in quantum mechanics, the physics of the smallest scales. Experiments to explicitly test this rule began only recently. Born's rule states that quantum paths interfere only in pairs. This means that the diffraction pattern produced by photons from a coherent source of light incident on 3 open slits is a combination of single slit diffraction and double slit interference. According to Born's rule, there is no higher order interference term. These 3-slit experiments can calculate the Sorkin parameter that characterizes the degree of agreement between Born's rule and their results. Our previous work demonstrates that the normalization scheme used to calculate the Sorkin parameter in those 3-slit experiments is very sensitive to experimental conditions, limiting the impact of the results. In this work, we explore new normalization schemes in order to find one that is more independent of the experimental setup. We gratefully acknowledge funding from the Hackman Summer Scholars program.

  8. Regulation of Drosophila Brain Wiring by Neuropil Interactions via a Slit-Robo-RPTP Signaling Complex.

    PubMed

    Oliva, Carlos; Soldano, Alessia; Mora, Natalia; De Geest, Natalie; Claeys, Annelies; Erfurth, Maria-Luise; Sierralta, Jimena; Ramaekers, Ariane; Dascenco, Dan; Ejsmont, Radoslaw K; Schmucker, Dietmar; Sanchez-Soriano, Natalia; Hassan, Bassem A

    2016-10-24

    The axonal wiring molecule Slit and its Round-About (Robo) receptors are conserved regulators of nerve cord patterning. Robo receptors also contribute to wiring brain circuits. Whether molecular mechanisms regulating these signals are modified to fit more complex brain wiring processes is unclear. We investigated the role of Slit and Robo receptors in wiring Drosophila higher-order brain circuits and identified differences in the cellular and molecular mechanisms of Robo/Slit function. First, we find that signaling by Robo receptors in the brain is regulated by the Receptor Protein Tyrosine Phosphatase RPTP69d. RPTP69d increases membrane availability of Robo3 without affecting its phosphorylation state. Second, we detect no midline localization of Slit during brain development. Instead, Slit is enriched in the mushroom body, a neuronal structure covering large areas of the brain. Thus, a divergent molecular mechanism regulates neuronal circuit wiring in the Drosophila brain, partly in response to signals from the mushroom body.

  9. DEVELOPMENT OF A HYDROSTATIC JOURNAL BEARING WITH SLIT-STEP COMPENSATION

    SciTech Connect

    Hale, L C; Donaldson, R R; Castro, C; Chung, C A; Hopkins, D J

    2006-07-28

    This paper describes the mathematical modeling and initial testing of an oil-hydrostatic bearing that derives compensation from both a central radial slit where fluid enters and stepped clearances near each end. Bearings using either a radial slit or stepped clearances for compensation were well studied over forty years ago by Donaldson. These bearings have smooth bores uninterrupted with multiple recesses around the circumference. The present slit-step bearing achieves the best of both types with somewhat higher hydrostatic stiffness than the slit bearing and fluid shear drag lower than the step bearing. This is apparent in TABLE 1, which compares calculated values of initial (i.e., centered) hydrostatic stiffness for each type. The slit-step bearing is one of several types being studied at Lawrence Livermore National Laboratory for possible use on the Precision Optical Grinder and Lathe (POGAL).

  10. An adjustable slit mechanism for a fiber-fed multi-object spectrograph

    NASA Astrophysics Data System (ADS)

    Bailey, John I.; Mateo, Mario L.; Bagish, Alan P.; Crane, Jeffrey D.; Slater, Colin T.

    2012-09-01

    Fiber-fed multi-object spectrographs have greatly enhanced the spectroscopic capabilities of the world's premiere telescopes, but their flexibility has typically been limited by a fixed effective slit size that constrains the available resolving power. We present a novel mechanism that, for the first time, equips a fiber-fed spectrograph with multiple discreet slits of different widths. In this paper, we detail the mechanical design of our variable slit mechanism, which is capable of positioning any one of six slits in front of the fibers immediately prior to injection into the spectrograph's optical train. Further, we present the details of related systems necessary to achieve closed loop positioning of the slit mechanism given that no encoder is used. We also briefly discuss our use of open source and open hardware projects in the design. Finally, we describe the control system we have implemented for this subsystem.

  11. Source-model technique analysis of electromagnetic scattering by surface grooves and slits.

    PubMed

    Trotskovsky, Konstantin; Leviatan, Yehuda

    2011-04-01

    A computational tool, based on the source-model technique (SMT), for analysis of electromagnetic wave scattering by surface grooves and slits is presented. The idea is to use a superposition of the solution of the unperturbed problem and local corrections in the groove/slit region (the grooves and slits are treated as perturbations). In this manner, the solution is obtained in a much faster way than solving the original problem. The proposed solution is applied to problems of grooves and slits in otherwise planar or periodic surfaces. Grooves and slits of various shapes, both smooth ones as well as ones with edges, empty or filled with dielectric material, are considered. The obtained results are verified against previously published data.

  12. Modelling the dynamics of condensation and evaporation of fluids in three-dimensional slit pores

    NASA Astrophysics Data System (ADS)

    Casselman, Joshua A.; Desouza, Anish; Monson, Peter A.

    2015-05-01

    We present an application of dynamic mean field theory (DMFT) for lattice gas models of confined fluids to the case of a fluid in a three-dimensional narrow slit between two plates. We consider a process where the slit is in contact with a subcritical bulk vapour and the bulk chemical potential is changed from a dilute gas value to a value close to that of the bulk saturated vapour so that capillary condensation occurs in the pore. DMFT predicts that the nucleation process during the condensation occurs by the formation of multiple liquid bridges spanning the pore walls, starting in the corners of the slit. These bridges eventually coalesce and the condensation transition terminates through the shrinkage and disappearance of a vapour bubble. We find that the density distribution is sensitive to the dimensions of the slit, with the number of bridges increasing with the slit area.

  13. Enhancement of the contrast ratio associated with surface waves in a metal pillar-slit structure

    SciTech Connect

    Zhou Yunsong; Zhao Liming; Wang Huaiyu; Lan Sheng

    2011-03-15

    A simple optical structure, termed a pillar-slit structure, is proposed to enhance the contrast ratio of the weak optical signal. The structure consists of a metal slit surrounded by two metal pillars and can be directly incorporated onto optical sensors. The waves excited on the incident surface are modulated by the pillars and then scattered by the slit entrance so as to generate the in-slit surface plasmon polaritons passing through the slit. The transmission power is modified by the surface wave intensity. This structure is capable of suppressing background and enhancing signal light simultaneously. A calculated illustration by the numerical simulation method shows that an increase of the contrast ratio can be exceeded 900 times.

  14. Chemical "Double Slits": dynamical interference of photodissociation pathways in water

    PubMed

    Dixon; Hwang; Yang; Harich; Lin; Yang

    1999-08-20

    Photodissociation of water at a wavelength of 121.6 nanometers has been investigated by using the H-atom Rydberg tagging technique. A striking even-odd intensity oscillation was observed in the OH(X) product rotational distribution. Model calculations attribute this oscillation to an unusual dynamical interference brought about by two dissociation pathways that pass through dissimilar conical intersections of potential energy surfaces, but result in the same products. The interference pattern and the OH product rotational distribution are sensitive to the positions and energies of the conical intersections, one with the atoms collinear as H-OH and the other as H-HO. An accurate simulation of the observations would provide a detailed test of global H(2)O potential energy surfaces for the three (&Xtilde;/A/&Btilde;) contributing states. The interference observed from the two conical intersection pathways provides a chemical analog of Young's well-known double-slit experiment.

  15. Young's double-slit interference for quantum particles

    NASA Astrophysics Data System (ADS)

    Ozer, Zehra Nur; Chaluvadi, Hari; Ulu, Melike; Dogan, Mevlut; Aktas, Bekir; Madison, Don

    2013-04-01

    For the last 50 years, there has been considerable interest in the possibility of observing the equivalence of a Young's double-slit wave interference at the quantum level for diatomic molecules. For electron-impact ionization of diatomic molecules, indirect evidence for this type of interference has been found by changing the energy (wavelength) of the ejected electron while keeping the incident projectile scattering angle fixed. The present work represents an experimental and theoretical collaboration to better understand the physics of this type of interference. In addition to examining the effect of changing the ejected electron energy for a fixed scattered projectile angle, we have also examined the effect of keeping the ejected electron energy fixed while varying the projectile scattering angle. Model calculations are performed for three different types of possible two-center interference effects, and it is found that the most important one is diffraction of the projectile off two scattering centers.

  16. Benefit of SLIT and SCIT for Allergic Rhinitis and Asthma.

    PubMed

    Passalacqua, Giovanni; Canonica, Giorgio Walter; Bagnasco, Diego

    2016-11-01

    Allergen immunotherapy (AIT) has been in use since more than one century, when Leonard Noon experimentally proved its efficacy in hayfever (Noon, in Lancet 1:1572-3, 1911). Since then, AIT was administered only as subcutaneous injections (SCIT) until the sublingual route (SLIT) was proposed in 1986. The use of SLIT was proposed following several surveys from the USA and UK that repeatedly reported fatalities due to SCIT (Lockey et al. in J Allergy Clin Immunol 75(1): 166, 1985; Lockey et al. in J Allergy Clin Immunol 660-77, 1985; Committee on the safety of medicines. CSM update. Desensitizing vaccines. Br Med J, 293: 948, 1986). These reports raised serious concerns about the safety and the risk/benefit ratio of AIT. Many cases of life-threatening events with SCIT were due to avoidable human errors in administration, but a relevant fraction of them remained unexplained and unpredictable (Aaronson and Gandhi in J Allergy Clin Immunol 113: 1117-21, 2014). Subsequently, in a few years, SLIT gained credibility and was included in the official documents and guidelines (Table 1) (Bousquet et al. in J Allergy Clin Immunol 108(5 Supp):S146-S150, 2001; Canonica et al. in Allergy 64 (Supp 91):1-59, 2009) as a viable alternative to traditional SCIT. Of note, the local bronchial (aerosol) and the intranasal route of administration were attempted after the 1970s as alternatives to SCIT: the bronchial route was soon abandoned due to the poor efficacy and/or side effects, and the local nasal route, although effective and safe, was judged substantially impractical (Canonica and Passalacqua in J Allergy Clin Immunol 111: 437-48, 2003). In contrast to SCIT, SLIT was tested in very large clinical trials (need references), including hundreds of patients and with dose-ranging experimental designs, so that some products (tablets) for grass, mite, and ragweed were officially approved as commercial drugs by regulatory agencies such as the Food and Drug Administration and the European

  17. 3-D Printed Slit Nozzles for Fourier Transform Microwave Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dewberry, Chris; Mackenzie, Becca; Green, Susan; Leopold, Ken

    2015-06-01

    3-D printing is a new technology whose applications are only beginning to be explored. In this report, we describe the application of 3-D printing to the facile design and construction of supersonic nozzles. The efficacy of a variety of designs is assessed by examining rotational spectra OCS and Ar-OCS using a Fourier transform microwave spectrometer with tandem cavity and chirped-pulse capabilities. This work focuses primarily on the use of slit nozzles but other designs have been tested as well. New nozzles can be created for 0.50 or less each, and the ease and low cost should facilitate the optimization of nozzle performance (e.g., jet temperature or cluster size distribution) for the needs of any particular experiment.

  18. Fabrication of metallic nano-slit waveguides with sharp bends.

    SciTech Connect

    Lu, M.; Ocola, L. E.; Gray, S. K.; Wiederrecht, G.; Center for Nanoscale Materials

    2008-01-01

    Metallic nanoslit waveguides are promising candidates for ultrahigh-density optical interconnections. A variety of devices based on metallic nanoslit waveguides have already been proposed that show a great superiority over conventional photonic devices for compactness. However very few two-dimensional devices have been experimentally demonstrated with in-plane geometries due to fabrication difficulties. In this article, a feasible process is presented using traditional semiconductor fabrication technologies such as mix-and-match lithography and electroplating, which is capable of fabricating complicated 100 nm wide, 800 nm deep gold slit waveguides with multiple sharp right-angle corners. The process can be extended to volume production manufacturing with minor modifications, thus enabling the fabrication of nanoslit photonic circuits and networks.

  19. Dynamics of cerebrospinal fluid flow in slit ventricle syndrome.

    PubMed

    Eymann, Regina; Schmitt, Melanie; Antes, Sebastian; Shamdeen, Mohammed Ghiat; Kiefer, Michael

    2012-01-01

    Although slit ventricle syndrome (SVS) is identified as a serious complication in shunt-treated hydrocephalus, cerebral spinal fluid (CSF) flow via external ventricular drainage (EVD) or shunts in SVS have not been studied up to now. A new apparatus (LiquoGuard(®); Möller-Medical, Fulda, Germany) was used for EVD in a child with SVS. The LiquoGuard actively controls CSF drainage, based on intracranial pressure (ICP). To achieve well-tolerated clinical conditions, an ICP level of 4 mmHg was necessary; realizable by drainage rates between 0 and 35 mL/h. Drainage rate variations typically occurred with repetitive time intervals of 2 h causing a "saw tooth" shaped CSF flow pattern throughout 24 h. SVS seems to be characterized largely by quickly varying CSF drainage demands. Whether this is a general phenomenon or just true for this case has still to be studied and needs further clarification.

  20. Nonresonant 104 Terahertz Field Enhancement with 5-nm Slits

    PubMed Central

    Suwal, Om Krishna; Rhie, Jiyeah; Kim, Nayeon; Kim, Dai-Sik

    2017-01-01

    Transmission of Terahertz (THz) electromagnetic wave through a substrate is encumbered because of scattering, multiple reflections, absorption, and Fabry–Perot effects when the wave interacts with the substrate. We present the experimental realization of nonresonant electromagnetic field enhancement by a factor of almost 104 in substrate-free 5-nm gold nanoslits. Our nanoslits yielded greater than 90% normalized electric field transmission in the low-frequency THz region; the slit width was 5 nm, and the gap coverage ratio was 10−4 of the entire membrane, 0.42 mm2. This large field enhancement was attributed to gap plasmons generated by the THz wave, which squeezes the charge cross-section, thus enabling very highly dense oscillating charges and strong THz field transmission from the nanoslits. PMID:28368048

  1. Weak Measurements of Light Chirality with a Plasmonic Slit

    NASA Astrophysics Data System (ADS)

    Gorodetski, Y.; Bliokh, K. Y.; Stein, B.; Genet, C.; Shitrit, N.; Kleiner, V.; Hasman, E.; Ebbesen, T. W.

    2012-07-01

    We examine, both experimentally and theoretically, an interaction of tightly focused polarized light with a slit on a metal surface supporting plasmon-polariton modes. Remarkably, this simple system can be highly sensitive to the polarization of the incident light and offers a perfect quantum weak measurement tool with a built-in postselection in the plasmon-polariton mode. We observe the plasmonic spin Hall effect in both coordinate and momentum spaces which is interpreted as weak measurements of the helicity of light with real and imaginary weak values determined by the input polarization. Our experiment combines the advantages of (i) quantum weak measurements, (ii) near-field plasmonic systems, and (iii) high-numerical aperture microscopy in employing the spin-orbit interaction of light and probing light chirality.

  2. REDUCEME: Long-slit spectroscopic data reduction and analysis

    NASA Astrophysics Data System (ADS)

    Cardiel, N.; Gorgas, J.; Pedraz, S.; Cenarro, J.; Alonso, O.; Gil de Paz, A.; García-Dabó, E.; Sánchez-Blázquez, P.; Mármol-Queraltó, E.; Toloba, E.

    2015-08-01

    The astronomical data reduction package REDUCEME reduces and analyzes long-slit spectroscopic data. The package uses the unformatted FORTRAN raw data format, so requires FITS files be transformed to REDUCEME format; the reverse operation (from REDUCEME to FITS format) is also available. The package is a set of programs written in FORTRAN 77 and includes shell scripts (using the C shell syntax) to perform routine tasks; it can be extended by the inclusion of external programs. REDUCEME uses PGPLOT (ascl:1103.002) for line plots and images, and a subset of subroutines, called BUTTON, enables the user to communicate interactively with the image display employing graphic buttons. One advantage of using REDUCEME is that for each image an associated error image can also be processed throughout the reduction process, allowing for a careful control of the error propagation.

  3. Differential scanning calorimetric and Fourier transform infrared spectroscopic studies of the effects of cholesterol on the thermotropic phase behavior and organization of a homologous series of linear saturated phosphatidylserine bilayer membranes.

    PubMed

    McMullen, T P; Lewis, R N; McElhaney, R N

    2000-10-01

    We have examined the effects of cholesterol on the thermotropic phase behavior and organization of aqueous dispersions of a homologous series of linear disaturated phosphatidylserines by high-sensitivity differential scanning calorimetry and Fourier transform infrared spectroscopy. We find that the incorporation of increasing quantities of cholesterol progressively reduces the temperature, enthalpy, and cooperativity of the gel-to-liquid-crystalline phase transition of the host phosphatidylserine bilayer, such that a cooperative chain-melting phase transition is completely or almost completely abolished at 50 mol % cholesterol, in contrast to the results of previous studies. We are also unable to detect the presence of a separate anhydrous cholesterol or cholesterol monohydrate phase in our binary mixtures, again in contrast to previous reports. We further show that the magnitude of the reduction in the phase transition temperature induced by cholesterol addition is independent of the hydrocarbon chain length of the phosphatidylserine studied. This result contrasts with our previous results with phosphatidylcholine bilayers, where we found that cholesterol increases or decreases the phase transition temperature in a chain length-dependent manner (1993. Biochemistry, 32:516-522), but is in agreement with our previous results for phosphatidylethanolamine bilayers, where no hydrocarbon chain length-dependent effects were observed (1999. Biochim. Biophys. Acta, 1416:119-234). However, the reduction in the phase transition temperature by cholesterol is of greater magnitude in phosphatidylethanolamine as compared to phosphatidylserine bilayers. We also show that the addition of cholesterol facilitates the formation of the lamellar crystalline phase in phosphatidylserine bilayers, as it does in phosphatidylethanolamine bilayers, whereas the formation of such phases in phosphatidylcholine bilayers is inhibited by the presence of cholesterol. We ascribe the limited

  4. Spatial coherence measurement of a scanning laser system and applicability of the Zernike's approximation to the exit pupil on the scan mirror

    NASA Astrophysics Data System (ADS)

    Kubota, Shigeo

    2012-11-01

    Spatial coherence of the scanning laser beam was observed on the Young's experimental set up using 50-μm-wide, 200-μm-separation double slits, which measured the less than unity fringe visibility in the Fraunhofer diffraction pattern of the double slits illuminated by the scanning laser beam at horizontal scan frequency 21 kHz, while approximately unity in case of the illumination by the laser beam at rest. This fact allow us to use the Zernike's approximation when applying the van Cittert Zernike theorem to the scanning laser system such as the laser pico-projectors in order to estimate its speckle contrast in the projected image on the screen diffuser. The predicted and measured speckle contrasts showed excellent agreement on the screen illuminated by the laser projector.

  5. Two-slit experiment: quantum and classical probabilities

    NASA Astrophysics Data System (ADS)

    Khrennikov, Andrei

    2015-06-01

    Inter-relation between quantum and classical probability models is one of the most fundamental problems of quantum foundations. Nowadays this problem also plays an important role in quantum technologies, in quantum cryptography and the theory of quantum random generators. In this letter, we compare the viewpoint of Richard Feynman that the behavior of quantum particles cannot be described by classical probability theory with the viewpoint that quantum-classical inter-relation is more complicated (cf, in particular, with the tomographic model of quantum mechanics developed in detail by Vladimir Man'ko). As a basic example, we consider the two-slit experiment, which played a crucial role in quantum foundational debates at the beginning of quantum mechanics (QM). In particular, its analysis led Niels Bohr to the formulation of the principle of complementarity. First, we demonstrate that in complete accordance with Feynman's viewpoint, the probabilities for the two-slit experiment have the non-Kolmogorovian structure, since they violate one of basic laws of classical probability theory, the law of total probability (the heart of the Bayesian analysis). However, then we show that these probabilities can be embedded in a natural way into the classical (Kolmogorov, 1933) probability model. To do this, one has to take into account the randomness of selection of different experimental contexts, the joint consideration of which led Feynman to a conclusion about the non-classicality of quantum probability. We compare this embedding of non-Kolmogorovian quantum probabilities into the Kolmogorov model with well-known embeddings of non-Euclidean geometries into Euclidean space (e.g., the Poincaré disk model for the Lobachvesky plane).

  6. Dimensional reduction of duplex DNA under confinement to nanofluidic slits.

    PubMed

    Vargas-Lara, Fernando; Stavis, Samuel M; Strychalski, Elizabeth A; Nablo, Brian J; Geist, Jon; Starr, Francis W; Douglas, Jack F

    2015-11-14

    There has been much interest in the dimensional properties of double-stranded DNA (dsDNA) confined to nanoscale environments as a problem of fundamental importance in both biological and technological fields. This has led to a series of measurements by fluorescence microscopy of single dsDNA molecules under confinement to nanofluidic slits. Despite the efforts expended on such experiments and the corresponding theory and simulations of confined polymers, a consistent description of changes of the radius of gyration of dsDNA under strong confinement has not yet emerged. Here, we perform molecular dynamics (MD) simulations to identify relevant factors that might account for this inconsistency. Our simulations indicate a significant amplification of excluded volume interactions under confinement at the nanoscale due to the reduction of the effective dimensionality of the system. Thus, any factor influencing the excluded volume interaction of dsDNA, such as ionic strength, solution chemistry, and even fluorescent labels, can greatly influence the dsDNA size under strong confinement. These factors, which are normally less important in bulk solutions of dsDNA at moderate ionic strengths because of the relative weakness of the excluded volume interaction, must therefore be under tight control to achieve reproducible measurements of dsDNA under conditions of dimensional reduction. By simulating semi-flexible polymers over a range of parameter values relevant to the experimental systems and exploiting past theoretical treatments of the dimensional variation of swelling exponents and prefactors, we have developed a novel predictive relationship for the in-plane radius of gyration of long semi-flexible polymers under slit-like confinement. Importantly, these analytic expressions allow us to estimate the properties of dsDNA for the experimentally and biologically relevant range of contour lengths that is not currently accessible by state-of-the-art MD simulations.

  7. Ultra-sensing with slit-enhanced infrared spectroscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Mayerhöfer, Thomas G.; Knipper, Richard; Hübner, Uwe; Cialla-May, Dana; Weber, Karina; Popp, Jürgen

    2017-02-01

    Infrared spectroscopy enables the label-free detection of structure specific fingerprints of analytes. The sensitivity of corresponding methods can strongly be enhanced by attaching analytes on plasmonic active surfaces. We introduce a slit array metamaterial perfect absorber (SAMPA) [1] consisting of a dielectric layer sandwiched between two Au layers of which the upper layer is perforated with a periodic array of slits. This structure combines the principle of Extraordinary Optical Transmission (more light is transmitted through a hole than is incident on its surface) with that of Perfect Absorption (reflectance and transmittance are virtually zero). Accordingly, within the slights the electric fields are strongly enhanced and light-matter interaction is correspondingly greatly amplified. Thus, already small concentrations of analytes down to a monolayer can be detected and identified by their spectral fingerprints with a standard mid-infrared spectrometer. Closely related to the SAMPAs are plasmonic slit absorbers, which simply consist of slit arrays in thin gold layers deposited on a layer of Si3N4.[2] These slit arrays operate like unstructured gold layers if the incident light is polarized parallel to the long slit axes. In contrast, for light polarized perpendicular to the long slit axis, the plasmon is excited. By the introduction of a second slit, which is rotated relative to the first slit, both principal polarization states excite plasmon resonances which can be made to differ in wavelength. As a consequence, the operating wavelength range of this slit array can be tuned by adjusting the polarization state of the incoming light. [1] Mayerhöfer, T.G., et al.. ACS Photonics, 2015. 2(11): p. 1567-1575. [2] Knipper, R., et. al., in preparation.

  8. Acute cranial decompression in Meckel-Gruber syndrome and slit-ventricle syndrome with craniocephalic disproportion.

    PubMed

    Moses, Michael; Ranger, Adrianna; Yazdani, Arjang

    2011-11-01

    Slit-ventricle syndrome (SVS) is characterized by headaches associated with subnormal ventricular size in patients with shunt-treated hydrocephalus. It commonly occurs in children who have had shunts placed at an early age and is diagnosed when computed tomography scans are carried out to investigate suspected shunt obstruction with an accompanying rise in intracranial pressure (ICP). Overdrainage of cerebrospinal fluid may additionally result in craniocephalic disproportion, potentially by dampening the normal expansile pulsations of the dura against the skull, which leads to craniostenosis. Management is controversial because many strategies have only short-term benefit, and surgical intervention is understandably often seen as a last resort.We present a case of a child with SVS and craniocephalic disproportion who was treated with urgent cranial expansion due to rising ICP. Intraoperative ICP monitoring demonstrates a rapid and sustained drop in ICP, and the patient made an uneventful return to his premorbid condition. We conclude that cranial vault expansion should be considered as an effective treatment for postshunt craniocephalic disproportion in patients with SVS.

  9. Solid particle impingement erosion characteristics of cylindrical surfaces, pre-existing holes and slits

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Buckley, D. H.

    1983-01-01

    The erosion characteristics of aluminum cylinders sand-blasted with both spherical and angular erodent particles were studied and compared with results from previously studied flat surfaces. The cylindrical results are discussed with respect to impact conditions. The relationship between erosion rate and pit morphology (width, depth, and width to depth ratio) is established. The aspects of (1) erosion rate versus time curves on cylindrical surfaces; (2) long-term exposures; and (3) erosion rate versus time curves with spherical and angular particles are presented. The erosion morphology and characteristics of aluminum surfaces with pre-existing circular cylindrical and conical holes of different sizes were examined using weight loss measurements, scanning electron microscopy, a profilometer, and a depth gage. The morphological features (radial and concentric rings) are discussed with reference to flat surfaces, and the erosion features with spherical microglass beads. The similarities and differences of erosion and morphological features are highlighted. The erosion versus time curves of various shapes of holes are discussed and are compared with those of a flat surface. The erosion process at slits is considered.

  10. Novel regulated expression of the SLIT/ROBO pathway in the ovary: possible role during luteolysis in women.

    PubMed

    Dickinson, Rachel E; Myers, Michelle; Duncan, W Colin

    2008-10-01

    The human corpus luteum (CL) undergoes luteolysis, associated with marked tissue and vascular remodeling, unless conception occurs and the gland is rescued by human chorionic gonadotropin (hCG). In Drosophila the Slit gene product, a secreted glycoprotein, acts as a ligand for the roundabout (robo) transmembrane receptor. Together they influence the guidance and migration of neuronal and nonneuronal cells. In vertebrates three Slit (Slit1, Slit2, Slit3) and four Robo (Robo1, Robo2, Robo3/Rig-1, Robo4/Magic Robo) genes have been identified. ROBO1, SLIT2, and SLIT3 are also inactivated in human cancers and may regulate apoptosis and metastasis. Because processes such as apoptosis and tissue remodeling occur during the regression of the CL, the aim of this study was to investigate the expression, regulation, and effects of the SLIT and ROBO genes in human luteal cells. Immunohistochemistry and RT-PCR revealed that SLIT2, SLIT3, ROBO1, and ROBO2 are expressed in luteal steroidogenic cells and fibroblast-like cells of the human CL. Furthermore, using real-time quantitative PCR, expression of SLIT2, SLIT3, and ROBO2 was maximal in the late-luteal phase and significantly reduced after luteal rescue in vivo with exogenous hCG (P<0.05). Additionally, hCG significantly inhibited SLIT2, SLIT3, and ROBO2 expression in cultured luteinized granulosa cells (P<0.05). Blocking SLIT-ROBO activity increased migration and significantly decreased levels of apoptosis in primary cultures of luteal cells (P<0.05). Overall, these results suggest the SLIT/ROBO pathway could play an important role in luteolysis in women.

  11. Slit/Robo1 signaling regulates neural tube development by balancing neuroepithelial cell proliferation and differentiation

    SciTech Connect

    Wang, Guang; Li, Yan; Wang, Xiao-yu; Han, Zhe; Chuai, Manli; Wang, Li-jing; Ho Lee, Kenneth Ka; Geng, Jian-guo; Yang, Xuesong

    2013-05-01

    Formation of the neural tube is the morphological hallmark for development of the embryonic central nervous system (CNS). Therefore, neural tube development is a crucial step in the neurulation process. Slit/Robo signaling was initially identified as a chemo-repellent that regulated axon growth cone elongation, but its role in controlling neural tube development is currently unknown. To address this issue, we investigated Slit/Robo1 signaling in the development of chick neCollege of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH, UKural tube and transgenic mice over-expressing Slit2. We disrupted Slit/Robo1 signaling by injecting R5 monoclonal antibodies into HH10 neural tubes to block the Robo1 receptor. This inhibited the normal development of the ventral body curvature and caused the spinal cord to curl up into a S-shape. Next, Slit/Robo1 signaling on one half-side of the chick embryo neural tube was disturbed by electroporation in ovo. We found that the morphology of the neural tube was dramatically abnormal after we interfered with Slit/Robo1 signaling. Furthermore, we established that silencing Robo1 inhibited cell proliferation while over-expressing Robo1 enhanced cell proliferation. We also investigated the effects of altering Slit/Robo1 expression on Sonic Hedgehog (Shh) and Pax7 expression in the developing neural tube. We demonstrated that over-expressing Robo1 down-regulated Shh expression in the ventral neural tube and resulted in the production of fewer HNK-1{sup +} migrating neural crest cells (NCCs). In addition, Robo1 over-expression enhanced Pax7 expression in the dorsal neural tube and increased the number of Slug{sup +} pre-migratory NCCs. Conversely, silencing Robo1 expression resulted in an enhanced Shh expression and more HNK-1{sup +} migrating NCCs but reduced Pax7 expression and fewer Slug{sup +} pre-migratory NCCs were observed. In conclusion, we propose that Slit/Robo1 signaling is involved in regulating neural tube

  12. `Mathematical' Cracks Versus Artificial Slits: Implications in the Determination of Fracture Toughness

    NASA Astrophysics Data System (ADS)

    Markides, Ch. F.; Kourkoulis, S. K.

    2016-03-01

    An analytic solution is introduced for the stress field developed in a circular finite disc weakened by a central slit of arbitrary ratio of its edges and slightly rounded corners. The disc is loaded by radial pressure applied along two finite arcs of its periphery, anti-symmetric with respect to the disc's center. The motive of the study is to consider the stress field in a disc with a mechanically machined slit (finite distance between the two lips) in juxtaposition to the respective field in the same disc with a `mathematical' crack (zero distance between lips), which is the configuration adopted in case the fracture toughness of brittle materials is determined according to the standardized cracked Brazilian-disc test. The solution is obtained using Muskhelishvili's complex potentials' technique adopting a suitable conformal mapping function found, also, in Savin's milestone book. For the task to be accomplished, an auxiliary problem is first solved, namely, the infinite plate with a rectangular slit (in case the resultant force on the slit is zero and also the stresses and rotations at infinity are zero), by mapping conformally the area outside the slit onto the mathematical plane with a unit hole. The formulae obtained for the complex potentials permit the analytic exploration of the stress field along some loci of crucial practical importance. The influence of the slit's width on the local stress amplification and also on the stress concentration around the crown of the slit is quantitatively described. In addition, the role of the load-application mode (compression along the slit's longitudinal symmetry axis and tension normal to it) is explored. Results indicate that the two configurations are not equivalent in terms of the stress concentration factor. In addition, depending on the combination of the slit's width and the load-application mode, the point where the normal stress along the slit's boundary is maximized `oscillates' between the central point of

  13. Influence of polymer architecture and polymer-wall interaction on the adsorption of polymers into a slit-pore.

    PubMed

    Chen, Zhong; Escobedo, Fernando A

    2004-02-01

    The effects of molecular topology and polymer-surface interaction on the properties of isolated polymer chains trapped in a slit were investigated using off-lattice Monte Carlo simulations. Various methods were implemented to allow efficient simulation of molecular structure, confinement force, and free energy for a chain interacting with such "sticky" surfaces. The simulations were performed in the canonical ensemble, and the free energy was sampled via virtual slit-separation moves. Six different chain architectures were studied: linear, star-branched, dendritic, cyclic, two-node (i.e., containing two tetrafunctional intramolecular crosslinks), and six-node molecules. The first three topologies entail increasing degrees of branching, and the last three topologies entail increasing degrees of intramolecular bonding. The confinement force, monomer density profile, and conformational properties for all these systems were compared (for identical molecular weight N) and analyzed as a function of adsorption strength. The compensation point where the wall attraction counterbalances the polymer-slit exclusion effects was the focus of our study. It was found that the attractive energy at the compensation point, epsilon(c), is a weak increasing function of the chain length for excluded-volume chains. The value of epsilon(c) differs significantly for different topologies, and smaller values are associated with better-adsorbing molecules. Due to their globular shape and numerous chain ends, branched molecules (e.g., stars and dendrimers) experience a relatively small entropic penalty for adsorption at low adsorption force and moderate confinement. However, as the adsorption force increases, the more flexible linear chains reach the compensation point at a weaker attractive energy because of the ease with which monomers can be packed near the walls. In moderate to weak confinement, molecules with intramolecular cross-links, such as cyclic, two-node, and six-node molecules

  14. USP33 mediates Slit-Robo signaling in inhibiting colorectal cancer cell migration.

    PubMed

    Huang, Zhaohui; Wen, Pushuai; Kong, Ruirui; Cheng, Haipeng; Zhang, Binbin; Quan, Cao; Bian, Zehua; Chen, Mengmeng; Zhang, Zhenfeng; Chen, Xiaoping; Du, Xiang; Liu, Jianghong; Zhu, Li; Fushimi, Kazuo; Hua, Dong; Wu, Jane Y

    2015-04-15

    Originally discovered in neuronal guidance, the Slit-Robo pathway is emerging as an important player in human cancers. However, its involvement and mechanism in colorectal cancer (CRC) remains to be elucidated. Here, we report that Slit2 expression is reduced in CRC tissues compared with adjacent noncancerous tissues. Extensive promoter hypermethylation of the Slit2 gene has been observed in CRC cells, which provides a mechanistic explanation for the Slit2 downregulation in CRC. Functional studies showed that Slit2 inhibits CRC cell migration in a Robo-dependent manner. Robo-interacting ubiquitin-specific protease 33 (USP33) is required for the inhibitory function of Slit2 on CRC cell migration by deubiquitinating and stabilizing Robo1. USP33 expression is downregulated in CRC samples, and reduced USP33 mRNA levels are correlated with increased tumor grade, lymph node metastasis and poor patient survival. Taken together, our data reveal USP33 as a previously unknown tumor-suppressing gene for CRC by mediating the inhibitory function of Slit-Robo signaling on CRC cell migration. Our work suggests the potential value of USP33 as an independent prognostic marker of CRC.

  15. Semiconductor fabrication techniques for producing an ultra-flat reflective slit

    NASA Astrophysics Data System (ADS)

    Vandervelde, Thomas E.; Cabral, Michael J.; Wilson, John; Skrutskie, Michael

    2006-06-01

    The most difficult aspects in manufacturing a reflective slit substrate are achieving a precisely fabricated slit surrounded by an optically flat surface. A commonly used technique is to polish a metal substrate that has a slit cut by electric discharge machine (EDM) methods. This process can produce 'optically flat' surfaces; however, the EDM can produce a slit with edge roughness on the order of 10 microns and a RMS field roughness of ~1 micron. Here, we present a departure from these traditional methods and employ the advantages inherent in integrated circuit fabrication. By starting with a silicon wafer, we begin with a nearly atomically flat surface. In addition, the fabrication tools and methodologies employed are traditionally used for high precision applications: this allows for the placement and definition of the slit with high accuracy. If greater accuracy in slit definition is required, additional tools, such as a focused ion beam, are used to define the slit edge down to tens of nanometers. The deposition of gold, after that of a suitable bonding layer, in an ultra-high vacuum chamber creates a final surface without the need of polishing. Typical results yield a surface RMS-roughness of approximately 2nm. Most of the techniques and tools required for this process are commonly available at research universities and the cost to manufacture said mirrors is a small fraction of the purchase price of the traditional ones.

  16. SLIT2/ROBO2 signaling pathway inhibits nonmuscle myosin IIA activity and destabilizes kidney podocyte adhesion

    PubMed Central

    Fan, Xueping; Yang, Hongying; Kumar, Sudhir; Tumelty, Kathleen E.; Pisarek-Horowitz, Anna; Sharma, Richa; Chan, Stefanie; Tyminski, Edyta; Shamashkin, Michael; Belghasem, Mostafa; Henderson, Joel M.; Coyle, Anthony J.; Berasi, Stephen P.

    2016-01-01

    The repulsive guidance cue SLIT2 and its receptor ROBO2 are required for kidney development and podocyte foot process structure, but the SLIT2/ROBO2 signaling mechanism regulating podocyte function is not known. Here we report that a potentially novel signaling pathway consisting of SLIT/ROBO Rho GTPase activating protein 1 (SRGAP1) and nonmuscle myosin IIA (NMIIA) regulates podocyte adhesion downstream of ROBO2. We found that the myosin II regulatory light chain (MRLC), a subunit of NMIIA, interacts directly with SRGAP1 and forms a complex with ROBO2/SRGAP1/NMIIA in the presence of SLIT2. Immunostaining demonstrated that SRGAP1 is a podocyte protein and is colocalized with ROBO2 on the basal surface of podocytes. In addition, SLIT2 stimulation inhibits NMIIA activity, decreases focal adhesion formation, and reduces podocyte attachment to collagen. In vivo studies further showed that podocyte-specific knockout of Robo2 protects mice from hypertension-induced podocyte detachment and albuminuria and also partially rescues the podocyte-loss phenotype in Myh9 knockout mice. Thus, we have identified SLIT2/ROBO2/SRGAP1/NMIIA as a potentially novel signaling pathway in kidney podocytes, which may play a role in regulating podocyte adhesion and attachment. Our findings also suggest that SLIT2/ROBO2 signaling might be a therapeutic target for kidney diseases associated with podocyte detachment and loss. PMID:27882344

  17. Frequency characteristics of defect states in a two-dimensional phononic crystal with slit structure

    NASA Astrophysics Data System (ADS)

    Wang, X. P.; Jiang, P.; Chen, T. N.; Yu, K. P.

    2016-02-01

    In this paper, the defect state and band gap characteristics in a two-dimensional slit structure phononic crystal, consisting of slotted steel tubes embedded in an air matrix, are investigated theoretically and experimentally. Using the finite element method and supercell technique, the dispersion relationships and power transmission spectra of the slit structures are calculated. The vibration modes of the band gap edges are analyzed to clarify the mechanism of the generation of the band gaps. Additionally, the influence of the slit width on the band gaps in slit structure is investigated. The slit width was found to influence the band gaps; this is critical to understand for practical applications. Based on this finding, a method to form defect scatterers by changing the slit width of a single central scatterer, or one row of scatterers, in the perfect PC was developed. Defect bands can be induced by creating defects inside the original complete band gaps. The frequency can then be tuned by changing the slit width of defect scatterers. Meanwhile, the relationship between point defect and line defect is investigated. Finally, we verify the results of theoretical research by experiments. These results will help in fabricating devices such as acoustic filters and waveguides whose band frequency can be modulated.

  18. Ultrathin multi-slit metamaterial as excellent sound absorber: Influence of micro-structure

    NASA Astrophysics Data System (ADS)

    Ren, S. W.; Meng, H.; Xin, F. X.; Lu, T. J.

    2016-01-01

    An ultrathin (subwavelength) hierarchy multi-slit metamaterial with simultaneous negative effective density and negative compressibility is proposed to absorb sound over a wide frequency range. Different from conventional acoustic metamaterials having only negative real parts of acoustic parameters, the imaginary parts of effective density and compressibility are both negative for the proposed metamaterial, which result in superior viscous and thermal dissipation of sound energy. By combining the slit theory of sound absorption with the double porosity theory for porous media, a theoretical model is developed to investigate the sound absorption performance of the metamaterial. To verify the model, a finite element model is established to calculate the effective density, compressibility, and sound absorption of the metamaterial. It is theoretically and numerically confirmed that, upon introducing micro-slits into the meso-slits matrix, the multi-slit metamaterial possesses indeed negative imaginary parts of effective density and compressibility. The influence of micro-slits on the acoustical performance of the metamaterial is analyzed in the context of its specific surface area and static flow resistivity. This work shows great potential of multi-slit metamaterials in noise control applications that require both small volume and small weight of sound-absorbing materials.

  19. Metalenses based on the non-parallel double-slit arrays

    NASA Astrophysics Data System (ADS)

    Shao, Hongyan; Chen, Chen; Wang, Jicheng; Pan, Liang; Sang, Tian

    2017-09-01

    Metalenses based on surface plasmon polaritons have played an indispensable role in ultra-thin devices designing. The amplitude, phase and polarization of electromagnetic waves all can be controlled easily by modifying the metasurface structures. Here we propose and investigate a new type of structure with Babinet-inverted nano-antennas which can provide a series of unit-cells with phase-shifts covering 2π and ensure almost same transmittance simultaneously. As a result, the wavefront can be manipulated by arraying the units in course. Metalenses with the linear asymmetrical double slit unit-cell arrays are designed and the simulative results exhibit their perfect focusing characteristics, including single-focus lenses and multi-focus lenses. The small focus size and high numerical aperture make them stand out from the traditional counterparts in application of precision sensing devices. We expect our designs will provide new insights in the practical applications for metasurfaces in data storages, optical information processing and optical holography.

  20. Stirling-type pulse tube refrigerator with slit-type heat exchangers for HTS superconducting motor

    NASA Astrophysics Data System (ADS)

    Ki, Taekyung; Jeong, Sangkwon

    2011-06-01

    A cryogenic refrigeration system is one of the indispensable components for cooling superconducting motor or generator. Among various configurations of cryogenic refrigeration system, the on-board refrigeration system is considered to be attractive for compactness and small heat leak. In order to turn this concept into reality, we focus on two essential points; development of the specific structure for on-board refrigeration and optimal design of the refrigerator. Since the on-board refrigeration system should not create unbalanced vibration, the inline Stirling-type pulse tube refrigerator is considered as a good candidate and more concrete and efficient structure is developed under the design constraints. The dynamic absorber is used to maintain the dynamic stability of the single acting linear compressor. To increase thermal Carnot efficiency with the on-board Stirling-type pulse tube refrigerator, slit-type heat exchangers are implemented and flow straighteners are carefully designed by the three-dimensional CFD simulation. The overall configuration of the Stirling-type pulse tube refrigerator is designed and fabricated by the optimal process. The present on-board refrigerator has the cooling capacity of 7 W at 59.5 K with the Carnot efficiency of 10.9%. According to these experimental results, the pulse tube refrigerator as the on-board refrigeration system possesses a sufficient thermal efficiency despite the restricted design configuration. The on-board refrigeration is considered as a useful method for cooling HTS superconducting motor.

  1. Investigation of digital sun sensor technology with an N-shaped slit mask.

    PubMed

    Wei, Min-Song; Xing, Fei; Li, Bin; You, Zheng

    2011-01-01

    Nowadays sun sensors are being more widely used in satellites to determine the sunray orientation, thus development of a new version of sun sensor with lighter mass, lower power consumption and smaller size it of considerable interest. This paper introduces such a novel digital sun sensor, which is composed of a micro-electro-mechanical system (MEMS) mask with an N-shaped slit as well as a single linear array charge-coupled device (CCD). The sun sensor can achieve the measurement of two-axis sunray angles according to the three sun spot images on the CCD formed by sun light illumination through the mask. Given the CCD glass layer, an iterative algorithm is established to correct the refraction error. Thus, system resolution, update rate and other characteristics are improved based on the model simulation and system design. The test of sun sensor prototype is carried out on a three-axis rotating platform with a sun simulator. The test results show that the field of view (FOV) is ±60° × ±60° and the accuracy is 0.08 degrees of arc (3σ) in the whole FOV. Since the power consumption of the prototype is only 300 mW and the update rate is 14 Hz, the novel digital sun sensor can be applied broadly in micro/nano-satellites, even pico-satellites.

  2. Expression of the repulsive SLIT/ROBO pathway in the human endometrium and Fallopian tube.

    PubMed

    Duncan, W C; McDonald, S E; Dickinson, R E; Shaw, J L V; Lourenco, P C; Wheelhouse, N; Lee, K-F; Critchley, H O D; Horne, A W

    2010-12-01

    We investigated whether the repulsive SLIT/ROBO pathway is expressed in the endometrium and is negatively regulated during implantation. We also examined whether deficient expression in the Fallopian tube (FT) may predispose to ectopic pregnancy (EP). Endometrium (n = 21) and FT (n = 17) were collected across the menstrual cycle from fertile women with regular cycles. Decidualized endometrium (n = 6) was obtained from women undergoing termination, and FT (n = 6) was obtained from women with EP. SLIT/ROBO expression was quantified by reverse transcription-PCR and protein localized by immunohistochemistry. The regulation of SLIT/ROBO expression in vitro, by sex steroids and hCG, was assessed in endometrial (hTERT-EEpC) epithelial cells, and the effects of Chlamydia trachomatis infection and smoking were studied in oviductal (OE-E6/E7) epithelial cells. Endometrial SLIT3 was highest in the mid-secretory phase (P = 0.0003) and SLIT1,2 and ROBO1 showed a similar trend. ROBO2 was highest in proliferative phase (P = 0.027) and ROBO3,4 showed a similar trend. SLIT2,3 and ROBO1, 4 were lower in decidua compared with mid-secretory endometrium (P < 0.05). SLITs and ROBOs, excepting ROBO2, were expressed in FT but there were no differences across the cycle or in EP. SLIT/ROBO proteins were localized to endometrial and FT epithelium. Treatment of hTERT-EEpC with a combination of estradiol and medroxyprogesterone acetate inhibited ROBO1 expression (P < 0.01) but hCG had no effect. Acute treatment of OE-E6/E7 with smoking metabolite, cotinine, and C. trachomatis had no effect. These findings imply a regulated role for the endometrial SLIT/ROBO interaction during normal development and pregnancy but that it may not be important in the aetiology of EP.

  3. Tapered-slit membrane filters for high-throughput viable circulating tumor cell isolation.

    PubMed

    Kang, Yoon-Tae; Doh, Il; Cho, Young-Ho

    2015-04-01

    This paper presents tapered-slit membrane filters for high-throughput viable circulating tumor cell (CTC) isolation. The membrane filter with a 2D array of vertical tapered slits with a gap that is wide at the entrance and gradually decreases with depth, provide minimal cell stress and reduce 82.14% of the stress generated in conventional straight-hole filters. We designed two types of tapered-slit filters, Filters 6 and 8, respectively, containing the tapered slits with outlet widths of 6 μm and 8 μm at a slit density of 34,445/cm(2) on the membrane. We fabricated the vertical slits with a tapered angle of 2 ° on a SU8 membrane by adjusting the UV expose dose and the air gap between the membrane and the photomask during lithography. In the experimental study, the proposed tapered-slit filter captured 89.87% and 82.44% of the cancer cells spiked in phosphate buffered saline (PBS) and diluted blood (blood: PBS = 1:4), respectively, at a sample flow rate of 5 ml per hour, which is 33.3 times faster than previous lateral tapered-slit filters. We further verified the capability to culture on chip after capturing: 72.33% of cells among the captured cells still remained viable after a 5-day culture. The proposed tapered-slit membrane filters verified high-throughput viable CTC isolation capability, thereby inaugurating further advanced CTC research for cancer diagnosis and prognosis.

  4. Slit-roundabout signaling regulates the development of the cardiac systemic venous return and pericardium.

    PubMed

    Mommersteeg, Mathilda T M; Andrews, William D; Ypsilanti, Athena R; Zelina, Pavol; Yeh, Mason L; Norden, Julia; Kispert, Andreas; Chédotal, Alain; Christoffels, Vincent M; Parnavelas, John G

    2013-02-01

    The Slit-Roundabout (Robo) signaling pathway has pleiotropic functions during Drosophila heart development. However, its role in mammalian heart development is largely unknown. To analyze the role of Slit-Robo signaling in the formation of the pericardium and the systemic venous return in the murine heart. Expression of genes encoding Robo1 and Robo2 receptors and their ligands Slit2 and Slit3 was found in or around the systemic venous return and pericardium during development. Analysis of embryos lacking Robo1 revealed partial absence of the pericardium, whereas Robo1/2 double mutants additionally showed severely reduced sinus horn myocardium, hypoplastic caval veins, and a persistent left inferior caval vein. Mice lacking Slit3 recapitulated the defects in the myocardialization, alignment, and morphology of the caval veins. Ligand binding assays confirmed Slit3 as the preferred ligand for the Robo1 receptor, whereas Slit2 showed preference for Robo2. Sinus node development was mostly unaffected in all mutants. In addition, we show absence of cross-regulation with previously identified regulators Tbx18 and Wt1. We provide evidence that pericardial defects are created by abnormal localization of the caval veins combined with ectopic pericardial cavity formation. Local increase in neural crest cell death and impaired neural crest adhesive and migratory properties underlie the ectopic pericardium formation. A novel Slit-Robo signaling pathway is involved in the development of the pericardium, the sinus horn myocardium, and the alignment of the caval veins. Reduced Slit3 binding in the absence of Robo1, causing impaired cardiac neural crest survival, adhesion, and migration, underlies the pericardial defects.

  5. Roundabout gene family functions during sensory axon guidance in the drosophila embryo are mediated by both Slit-dependent and Slit-independent mechanisms.

    PubMed

    Parsons, Linda; Harris, Kerri-Lee; Turner, Kirsty; Whitington, Paul M

    2003-12-15

    roundabout (robo) family genes play key roles in axon guidance in a wide variety of animals. We have investigated the roles of the robo family members, robo, robo2, and robo3, in the guidance of sensory axons in the Drosophila embryo. In robo(-/-), slit(-/-), and robo(-/+) slit(-/+) mutants, lateral cluster sensory neurons misproject to cells and axons in the nearby ventral' (v') cluster. These phenotypes, together with the normal expression pattern of Slit and Robo, suggest that Slit ligand secreted from the epidermis interacts with Robo receptors on lateral cluster sensory growth cones to limit their exploration of nearby attractive substrates. The most common sensory axon phenotype seen in robo2(-/-) mutants was misprojection of dorsal cluster sensory axons away from their normal growth substrate, the transverse connective of the trachea. slit appears to play no role in this aspect of sensory axon growth. Robo2 is expressed, not on the dorsal sensory axons, but on the transverse connective. These results suggest a novel, non-cell-autonomous mechanism for axon guidance by robo family genes: Robo2 expressed on the trachea acts as an attractant for the dorsal sensory growth cones.

  6. Measurement of the absolute accuracy (to <0.5%) of a clip-level beam profiler using Fresnel diffraction by a wide slit

    NASA Astrophysics Data System (ADS)

    Johnston, Thomas F., Jr.; Fleischer, John M.

    1995-04-01

    By comparing the measured width of an optical test patten to the known width, the absolute error of a clip-level profiler is determined to be (-0.1 +/- 0.3)%. An expanded fundamental mode beam illuminates a pair of opposed knife edges (a wide slit) to generate the test pattern by Fresnel diffraction. Analysis of the diffraction pattern gives 18.2% as the appropriate clip level to read the geometrical shadow width between edges (with additional small adjustments for illumination non-uniformity and the finite size of the scanning aperture). The separation between the edges is determined by mechanical translation edge to edge through a focused beam. 3

  7. Young's experiment with a double slit of sub-wavelength dimensions.

    PubMed

    Lee, Kanghee; Lim, Jongseok; Ahn, Jaewook

    2013-08-12

    We report that the interference pattern of Young's double-slit experiment changes as a function of polarization in the sub-wavelength diffraction regime. Experiments carried out with terahertz time-domain spectroscopy reveal that diffracted waves from sub-wavelength-scale slits exhibit either positive or negative phase shift with respect to Gouy phase depending on the polarization. Theoretical explanation based on the induction of electric current and magnetic dipole in the vicinity of the slits shows an excellent agreement with the experimental results.

  8. Single-Slit Diffraction: Transitioning from Geometric Optics to the Fraunhofer Regime

    NASA Astrophysics Data System (ADS)

    Panuski, Christopher L.; Mungan, Carl E.

    2016-09-01

    Suppose a red laser beam (of wavelength λ equal to 0.660 μm) is expanded using an optical telescope into a collimated, approximately plane wave that is 5.68 mm in diameter. Pass that beam through a tall rectangular slit whose width a is gradually reduced from 3.30 to 0.100 mm. Look at its image on a screen located at a distance L from the slit equal to 0.656 m. As the slit is narrowed, you predict that the width of the pattern will: (A) smoothly increase, (B) smoothly decrease, (C)increase and then decrease, or (D) decrease and then increase.

  9. Asymmetric acoustic convergence in a metal plate with binary wave-path slits

    NASA Astrophysics Data System (ADS)

    Sun, Hong-xiang; Huang, Yu-lei; Xia, Jian-ping; Yuan, Shou-qi

    2017-09-01

    We report both experimentally and numerically that asymmetric acoustic convergence is realized by perforating two types of slits (inclined and vertical slits) in a steel plate immersed in water. The asymmetric acoustic convergence phenomenon exists in the frequency band of 560 kHz-592 kHz, which is attributed to the interference enhancement and cancellation induced by the symmetric structure and the acoustic path differences from two types of slits. The proposed lens has the advantages of multi-functionality, broader bandwidth, and planar structure, which provides more possibilities for sound manipulation and improves the applications in various scenarios, such as focused ultrasound therapy and ultrasound imaging.

  10. A numerical study of isothermal flows of a slit V-gutter

    SciTech Connect

    Lin, C.K.; Chou, J.; Tsuei, Y.M.; Lee, D. National Cheng Kung University, Tainan, )

    1992-01-01

    In this study, flowfields of a slit V-gutter are investigated numerically. The flow pattern can be significantly different from that of a conventional V-gutter. For a small slit height h, two separate recirculation bubbles are formed. A smaller bubble is anchored behind the inner gutter, a larger one follows. With a larger h, the smaller bubble grows and the larger one shrinks. As h increases further, the two bubbles merge to form a single recirculation zone. The magnitude and the angle of the slit velocity play important roles in determining the strength of the recirculation zone. These results are consistent with that observed experimentally by other authors. 13 refs.

  11. Which-way double-slit experiments and Born-rule violation

    NASA Astrophysics Data System (ADS)

    Quach, James Q.

    2017-04-01

    In which-way double-slit experiments with perfect detectors, it is assumed that having a second detector at the slits is redundant because it will not change the interference pattern. We, however, show that if higher-order or nonclassical paths are accounted for, the presence of the second detector will have an effect on the interference pattern. Accounting for these nonclassical paths also means that the Sorkin parameter in triple-slit experiments is only an approximate measure of Born-rule violation. Using the difference between single and double which-way detectors, we give an alternative parameter which is an exact measure of Born-rule violation.

  12. Head CT scan

    MedlinePlus

    Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial; CAT scan - brain ... conditions: Birth (congenital) defect of the head or brain Brain infection Brain tumor Buildup of fluid inside ...

  13. From concave to convex: capillary bridges in slit pore geometry.

    PubMed

    Broesch, David J; Frechette, Joelle

    2012-11-06

    We investigate the morphological evolution of nonaxisymmetric capillary bridges in slit-pore geometry as the height of the pore and aspect ratio of the bridge are varied. The liquid bridges are formed between two hydrophobic surfaces patterned with hydrophilic strips. The aspect ratio of the capillary bridges (length/width) is varied from 2.5 to 120 by changing the separation between the surfaces, the width of the strips, or the fluid volume. As the bridge height is increased, the aspect ratio decreases and we observe a large increase in the mean curvature of the bridge. More specifically, the following counterintuitive result is observed: the mean curvature of the bridges changes sign and goes from negative (concave bridge) to positive (convex bridge) when the height is increased at constant volume. These experimental observations are in quantitative agreement with Surface Evolver simulations. Scaling shows a collapse of the data indicating that this transition in the sign of the Laplace pressure is universal for capillary bridges with high aspect ratios. Finally, we show that the morphology diagrams obtained from our 3D analysis are considerably different from those expected from a 2D analysis.

  14. Fabrication and visualization of capillary bridges in slit pore geometry.

    PubMed

    Broesch, David J; Frechette, Joelle

    2014-01-09

    A procedure for creating and imaging capillary bridges in slit-pore geometry is presented. High aspect ratio hydrophobic pillars are fabricated and functionalized to render their top surfaces hydrophilic. The combination of a physical feature (the pillar) with a chemical boundary (the hydrophilic film on the top of the pillar) provides both a physical and chemical heterogeneity that pins the triple contact line, a necessary feature to create stable long but narrow capillary bridges. The substrates with the pillars are attached to glass slides and secured into custom holders. The holders are then mounted onto four axis microstages and positioned such that the pillars are parallel and facing each other. The capillary bridges are formed by introducing a fluid in the gap between the two substrates once the separation between the facing pillars has been reduced to a few hundred micrometers. The custom microstage is then employed to vary the height of the capillary bridge. A CCD camera is positioned to image either the length or the width of the capillary bridge to characterize the morphology of the fluid interface. Pillars with widths down to 250 µm and lengths up to 70 mm were fabricated with this method, leading to capillary bridges with aspect ratios (length/width) of over 100(1).

  15. Calibration of structured light stripe system using plane with slits

    NASA Astrophysics Data System (ADS)

    Ha, Jong-Eun; Her, Kang-Wook

    2013-01-01

    Structured light stripe systems are widely used in industrial applications for acquiring three-dimensional (3-D) information. Calibration is the first necessary step and traditional algorithms compute the 4×3 transformation matrix from image to world. Therefore, 3-D information can be obtained with respect to the camera's coordinate system, and it cannot be transformed into the laser coordinate system. We propose a new calibration algorithm of a structured light system that can compute the relative pose of the laser coordinate system with respect to the camera coordinate system. We can convert 3-D information either to the laser coordinate system or to the camera coordinate system. The proposed algorithm uses two planes where one plane with multiple slits is set perpendicular to the other plane. We can easily compute the position and rotation of the laser coordinate system using proposed calibration structure. Also, we can solve the extrinsic calibration using just one shot of an image while conventional algorithms require more than two images under different poses. Experiments under various configurations show the feasibility of proposed algorithm.

  16. Low-cost endothelium cell counter for slit lamp

    NASA Astrophysics Data System (ADS)

    Ventura, Liliane; Faria de Sousa, Sidney J.; Ribeiro, Paulo E. M., Jr.; Caetano, Cesar A. C.

    1998-06-01

    One of the optical ways to evaluate the donated cornea in order to provide a diagnostic regarding its indication for transplant is to count the number of the living endothelial cells (over 2000 cells/mm2), which are responsible for maintaining the corneal transparency. Specular Microscopes are equipments which are exclusively dedicated for this kind of evaluation. However they are of high cost and most of the Eye Banks are not provided by them. Hence, the usual evaluation is done in a Slit Lamp (SL) -- 40X magnification -- and just the aspect of the cells are subjectively observed. In order to overcome the limitations of subjective assessment and high cost, we have developed a system attached to the SL (optical system with 250X magnification image captured by a CCD detector which displays the image of the cells on a PC monitor and a dedicated software) which is able to count the endothelial cells providing a lower cost objective diagnostic of the donated cornea.

  17. Theory of repulsive charged colloids in slit-pores

    NASA Astrophysics Data System (ADS)

    Gallardo, Alberto; Grandner, Stefan; Almarza, Noé G.; Klapp, Sabine H. L.

    2012-07-01

    Using classical density functional theory (DFT) we analyze the structure of the density profiles and solvation pressures of negatively charged colloids confined in slit pores. The considered model, which was already successfully employed to study a real colloidal (silica) suspension [S. H. L. Klapp et al., Phys. Rev. Lett. 100, 118303 (2008), 10.1103/PhysRevLett.100.118303], involves only the macroions which interact via the effective Derjaguin-Landau-Verwey-Overbeek (DLVO) potential supplemented by a hard core interaction. The solvent enters implicitly via the screening length of the DLVO interaction. The free energy functional describing the colloidal suspension consists of a hard sphere contribution obtained from fundamental measure theory and a long range contribution which is treated using two types of approximations. One of them is the mean field approximation (MFA) and the remaining is based on Rosenfeld's perturbative method for constructing the Helmholtz energy functional. These theoretical calculations are carried out at different bulk densities and wall separations to compare finally to grand canonical Monte Carlo simulations. We also consider the impact of charged walls. Our results show that the perturbative DFT method yields generally qualitatively consistent and, for some systems, also quantitatively reliable results. In MFA, on the other hand, the neglect of charge-induced correlations leads to a breakdown of this approach in a broad range of densities.

  18. Early regimes of water capillary flow in slit silica nanochannels.

    PubMed

    Oyarzua, Elton; Walther, Jens H; Mejía, Andrés; Zambrano, Harvey A

    2015-06-14

    Molecular dynamics simulations are conducted to investigate the initial stages of spontaneous imbibition of water in slit silica nanochannels surrounded by air. An analysis is performed for the effects of nanoscopic confinement, initial conditions of liquid uptake and air pressurization on the dynamics of capillary filling. The results indicate that the nanoscale imbibition process is divided into three main flow regimes: an initial regime where the capillary force is balanced only by the inertial drag and characterized by a constant velocity and a plug flow profile. In this regime, the meniscus formation process plays a central role in the imbibition rate. Thereafter, a transitional regime takes place, in which, the force balance has significant contributions from both inertia and viscous friction. Subsequently, a regime wherein viscous forces dominate the capillary force balance is attained. Flow velocity profiles identify the passage from an inviscid flow to a developing Poiseuille flow. Gas density profiles ahead of the capillary front indicate a transient accumulation of air on the advancing meniscus. Furthermore, slower capillary filling rates computed for higher air pressures reveal a significant retarding effect of the gas displaced by the advancing meniscus.

  19. Full controlling of Fano resonances in metal-slit superlattice.

    PubMed

    Deng, Zi-Lan; Yogesh, Natesan; Chen, Xiao-Dong; Chen, Wen-Jie; Dong, Jian-Wen; Ouyang, Zhengbiao; Wang, Guo Ping

    2015-12-18

    Controlling of the lineshape of Fano resonance attracts much attention recently due to its wide capabilities for lasing, biosensing, slow-light applications and so on. However, the controllable Fano resonance always requires stringent alignment of complex symmetry-breaking structures and thus the manipulation could only be performed with limited degrees of freedom and narrow tuning range. Furthermore, there is no report so far on independent controlling of both the bright and dark modes in a single structure. Here, we semi-analytically show that the spectral position and linewidth of both the bright and dark modes can be tuned independently and/or simultaneously in a simple and symmetric metal-slit superlattice, and thus allowing for a free and continuous controlling of the lineshape of both the single and multiple Fano resonances. The independent controlling scheme is applicable for an extremely large electromagnetic spectrum range from optical to microwave frequencies, which is demonstrated by the numerical simulations with real metal and a microwave experiment. Our findings may provide convenient and flexible strategies for future tunable electromagnetic devices.

  20. Numerical simulation of rarefied gas flow through a slit

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Jeng, Duen-Ren; De Witt, Kenneth J.; Chung, Chan-Hong

    1990-01-01

    Two different approaches, the finite-difference method coupled with the discrete-ordinate method (FDDO), and the direct-simulation Monte Carlo (DSMC) method, are used in the analysis of the flow of a rarefied gas from one reservoir to another through a two-dimensional slit. The cases considered are for hard vacuum downstream pressure, finite pressure ratios, and isobaric pressure with thermal diffusion, which are not well established in spite of the simplicity of the flow field. In the FDDO analysis, by employing the discrete-ordinate method, the Boltzmann equation simplified by a model collision integral is transformed to a set of partial differential equations which are continuous in physical space but are point functions in molecular velocity space. The set of partial differential equations are solved by means of a finite-difference approximation. In the DSMC analysis, three kinds of collision sampling techniques, the time counter (TC) method, the null collision (NC) method, and the no time counter (NTC) method, are used.

  1. Theory of repulsive charged colloids in slit-pores.

    PubMed

    Gallardo, Alberto; Grandner, Stefan; Almarza, Noé G; Klapp, Sabine H L

    2012-07-07

    Using classical density functional theory (DFT) we analyze the structure of the density profiles and solvation pressures of negatively charged colloids confined in slit pores. The considered model, which was already successfully employed to study a real colloidal (silica) suspension [S. H. L. Klapp et al., Phys. Rev. Lett. 100, 118303 (2008)], involves only the macroions which interact via the effective Derjaguin-Landau-Verwey-Overbeek (DLVO) potential supplemented by a hard core interaction. The solvent enters implicitly via the screening length of the DLVO interaction. The free energy functional describing the colloidal suspension consists of a hard sphere contribution obtained from fundamental measure theory and a long range contribution which is treated using two types of approximations. One of them is the mean field approximation (MFA) and the remaining is based on Rosenfeld's perturbative method for constructing the Helmholtz energy functional. These theoretical calculations are carried out at different bulk densities and wall separations to compare finally to grand canonical Monte Carlo simulations. We also consider the impact of charged walls. Our results show that the perturbative DFT method yields generally qualitatively consistent and, for some systems, also quantitatively reliable results. In MFA, on the other hand, the neglect of charge-induced correlations leads to a breakdown of this approach in a broad range of densities.

  2. Full controlling of Fano resonances in metal-slit superlattice

    NASA Astrophysics Data System (ADS)

    Deng, Zi-Lan; Yogesh, Natesan; Chen, Xiao-Dong; Chen, Wen-Jie; Dong, Jian-Wen; Ouyang, Zhengbiao; Wang, Guo Ping

    2015-12-01

    Controlling of the lineshape of Fano resonance attracts much attention recently due to its wide capabilities for lasing, biosensing, slow-light applications and so on. However, the controllable Fano resonance always requires stringent alignment of complex symmetry-breaking structures and thus the manipulation could only be performed with limited degrees of freedom and narrow tuning range. Furthermore, there is no report so far on independent controlling of both the bright and dark modes in a single structure. Here, we semi-analytically show that the spectral position and linewidth of both the bright and dark modes can be tuned independently and/or simultaneously in a simple and symmetric metal-slit superlattice, and thus allowing for a free and continuous controlling of the lineshape of both the single and multiple Fano resonances. The independent controlling scheme is applicable for an extremely large electromagnetic spectrum range from optical to microwave frequencies, which is demonstrated by the numerical simulations with real metal and a microwave experiment. Our findings may provide convenient and flexible strategies for future tunable electromagnetic devices.

  3. Wideband analytical equivalent circuit for coupled asymmetrical nonaligned slit arrays

    NASA Astrophysics Data System (ADS)

    Molero, Carlos; Rodríguez-Berral, Raúl; Mesa, Francisco; Medina, Francisco

    2017-02-01

    Microstructured metallic devices have been extensively studied because of their interesting properties for controlling the transmission, reflection, and absorption of electromagnetic waves. A very simple implementation is an array of infinitely long parallel metal strips printed on a dielectric substrate. In the past few years, several analytical models have been reported based on the use of equivalent circuits with distributed and lumped components to account for the electrical performance of these structures. However, the proposed models are restricted to highly symmetrical configurations of the basic unit cell of the periodic structure. The purpose of this paper is to present the nontrivial extension of such circuit models to deal with nonsymmetrical structures. More specifically, a wideband equivalent-circuit model will be developed to describe the scattering properties of a pair of coupled different nonaligned slit gratings printed on a dielectric slab of arbitrary thickness. The relevant consequences of the lack of symmetry of the structures under study will be thoroughly discussed. The obtained equivalent network can be straightforwardly used to model stacked structures with an arbitrary number of nonsymmetrical striplike arrays.

  4. Wideband analytical equivalent circuit for coupled asymmetrical nonaligned slit arrays.

    PubMed

    Molero, Carlos; Rodríguez-Berral, Raúl; Mesa, Francisco; Medina, Francisco

    2017-02-01

    Microstructured metallic devices have been extensively studied because of their interesting properties for controlling the transmission, reflection, and absorption of electromagnetic waves. A very simple implementation is an array of infinitely long parallel metal strips printed on a dielectric substrate. In the past few years, several analytical models have been reported based on the use of equivalent circuits with distributed and lumped components to account for the electrical performance of these structures. However, the proposed models are restricted to highly symmetrical configurations of the basic unit cell of the periodic structure. The purpose of this paper is to present the nontrivial extension of such circuit models to deal with nonsymmetrical structures. More specifically, a wideband equivalent-circuit model will be developed to describe the scattering properties of a pair of coupled different nonaligned slit gratings printed on a dielectric slab of arbitrary thickness. The relevant consequences of the lack of symmetry of the structures under study will be thoroughly discussed. The obtained equivalent network can be straightforwardly used to model stacked structures with an arbitrary number of nonsymmetrical striplike arrays.

  5. Full controlling of Fano resonances in metal-slit superlattice

    PubMed Central

    Deng, Zi-Lan; Yogesh, Natesan; Chen, Xiao-Dong; Chen, Wen-Jie; Dong, Jian-Wen; Ouyang, Zhengbiao; Wang, Guo Ping

    2015-01-01

    Controlling of the lineshape of Fano resonance attracts much attention recently due to its wide capabilities for lasing, biosensing, slow-light applications and so on. However, the controllable Fano resonance always requires stringent alignment of complex symmetry-breaking structures and thus the manipulation could only be performed with limited degrees of freedom and narrow tuning range. Furthermore, there is no report so far on independent controlling of both the bright and dark modes in a single structure. Here, we semi-analytically show that the spectral position and linewidth of both the bright and dark modes can be tuned independently and/or simultaneously in a simple and symmetric metal-slit superlattice, and thus allowing for a free and continuous controlling of the lineshape of both the single and multiple Fano resonances. The independent controlling scheme is applicable for an extremely large electromagnetic spectrum range from optical to microwave frequencies, which is demonstrated by the numerical simulations with real metal and a microwave experiment. Our findings may provide convenient and flexible strategies for future tunable electromagnetic devices. PMID:26680258

  6. New insights into implication of the SLIT/ROBO pathway in the prehierarchical follicle development of hen ovary.

    PubMed

    Qin, N; Fan, X C; Zhang, Y Y; Xu, X X; Tyasi, T L; Jing, Y; Mu, F; Wei, M L; Xu, R F

    2015-09-01

    The SLIT/Roundabout (ROBO) pathway is involved in follicle development of mammalian ovary, and 2 secreted hormones activin A and inhibin A have potential roles in modulation of the SLIT/ROBO system, but the related actions remain poorly understood in bird. The aims of the present study were to examine the spatial and temporal expression of the SLIT ligand genes (SLIT1, SLIT2, and SLIT3) and their receptor ROBO1, ROBO2, ROBO3, and ROBO4 genes in various-sized prehierarchical follicles during hen ovary development and the effects of activin A and inhibin A on the expression of these genes in the cultured hen follicles. Our result demonstrated that the transcripts of the 3 SLIT genes were highly expressed in the developing follicles and expression patterns of the SLIT transcripts were different from those of ROBO genes detected by real-time quantitative reverse transcriptase PCR. Both SLIT and ROBO transcripts were predominantly expressed in oocytes and granulosa cells from the prehierarchichal follicles examined by in situ hybridization. The localization for SLIT and ROBO proteins was revealed by immunohistochemistry similar to the spatial distribution of their transcript. In cultured follicles (4 to 8 mm in diameter), the expression levels of SLIT and ROBO members are hormonally regulated by activin A (10 ng/mL) and/or inhibin A (20 ng/mL) after treatment for 24 h. However, the expression of only SLIT2, SLIT3, and ROBO3 mRNA presented a directly opposite response to activin A and inhibin A hormones. These results indicate that SLIT/ROBO pathway is implicated in the prehierarchical follicular development of the hen ovary by an intrafollicular autocrine and/or paracrine action, and is influenced by activin A and inhibin A hormones.

  7. SLIT/ROBO2 Signaling Promotes Mammary Stem Cell Senescence by Inhibiting Wnt Signaling

    PubMed Central

    Harburg, Gwyndolen; Compton, Jennifer; Liu, Wei; Iwai, Naomi; Zada, Shahrzad; Marlow, Rebecca; Strickland, Phyllis; Zeng, Yi Arial; Hinck, Lindsay

    2014-01-01

    Summary WNT signaling stimulates the self-renewal of many types of adult stem cells, including mammary stem cells (MaSCs), but mechanisms that limit this activity are poorly understood. Here, we demonstrate that SLIT2 restricts stem cell renewal by signaling through ROBO2 in a subset of basal cells to negatively regulate WNT signaling. The absence of SLIT/ROBO2 signaling leads to increased levels of nuclear β-catenin. Robo2 loss does not increase the number of stem cells; instead, stem cell renewal is enhanced in the absence of SLIT/ROBO2 signaling. This is due to repressed expression of p16INK4a, which, in turn, delays MaSC senescence. Together, our studies support a model in which SLITs restrict the expansion of MaSCs by countering the activity of WNTs and limiting self-renewal. PMID:25241737

  8. Distributed angular double-slit interference with pseudo-thermal light

    NASA Astrophysics Data System (ADS)

    Gao, Lu; Hashemi Rafsanjani, Seyed Mohammad; Zhou, Yiyu; Yang, Zhe; Magaña-Loaiza, Omar S.; Mirhosseini, Mohammad; Zhao, Jiapeng; Gao, Boshen; Boyd, Robert W.

    2017-02-01

    We propose and perform an interference experiment involving a distributed angular double-slit and the orbital angular momentum (OAM) correlations of thermal light. In the experiment, two spatially separated angular apertures are placed in two correlated light beams generated by splitting the thermal light beam via a beam splitter. The superposition of the two spatially separated slits constitutes an angular double-slit in two-photon measurements. The angular interference pattern of the distributed double-slit is measured even though each beam interacts with a different part of the object. This scheme allows us to discriminate among different angular amplitude objects using a classical incoherent light source. This procedure has potential applications in remote sensing or optical metrology in the OAM domain.

  9. Diffraction imaging characteristics of slit for ultra-short laser pulse

    NASA Astrophysics Data System (ADS)

    Yu, Xiang-yang; Wu, Kun-xi; Lu, Long-zhao

    2015-08-01

    We propose a simple and concise mathematical method based on the Fraunhofer approximation to analyze the imaging characteristics of slit for broadband light sources. Taking Gaussian-shaped ultra-short laser pulse for example, we investigated the diffraction imaging characteristics of ultra-short light sources through a single-slit and a double-slit. We deduced the mathematical expressions of the intensity distribution of far-field diffraction, and conducted numerical calculation and analysis. It turns out the pulse width of the ultra-short light source plays an important role in the diffraction imaging characteristics of slit. We also provide a quantitative criterion to measure the deviation in terms of far-field diffraction intensity distribution between broadband light source and the ideal monochromatic light source.

  10. Optical forces on resonant metallic cylinders near supertransmitting slits illuminated by a photonic nanojet

    NASA Astrophysics Data System (ADS)

    Valero, Francisco Javier Valdivia; Vesperinas, Manuel Nieto

    2012-09-01

    We analyze optical forces exerted on 2D metallic particles, i. e. infinite cylinders, near a subwavelength slit in supertransmission regime and illuminated by a photonic nanojet, comparing the cases in which their plasmonic resonances are or are not excited. Furthermore, we show that illuminating the slit by means of a photonic nanojet even enhances the optical forces at the exit of the aperture by a factor between 3 and 10 compared to the case of the slit directly illuminated by the Gaussian beam. Also, the presence of the slit can change the pulling nature of the force that the direct illumination by the nanojet exerts on the small metallic particle in resonance, becoming repulsive at certain lateral positions of this latter.

  11. Research on the injected effect by the narrow-slit injection orifice in screw compressors

    NASA Astrophysics Data System (ADS)

    Xie, J.; Feng, J.; Liu, F.; Peng, C.; Feng, Q.

    2017-08-01

    A narrow-slit injection orifice in screw compressors (mainly in single screw compressors) is described in this paper. In contrast to the traditional injection orifice, the section is slit shaped but not circular. Liquid which is injected by the narrow-slit injection orifice appears as a curtain shape. The heat transfer area is increased so that the cooling effect is enhanced and the efficiency of the compressor is improved. The injected effect was simulated through the CFD software, and then the experiments were carried out. The study verified the accuracy of the simulation results and will provide a theoretical foundation for the design of a narrow-slit injection orifice in screw compressors.

  12. Slit disk for modified faraday cup diagnostic for determining power density of electron and ion beams

    DOEpatents

    Teruya, Alan T [Livermore, CA; Elmer,; John, W [Danville, CA; Palmer, Todd A [State College, PA

    2011-03-08

    A diagnostic system for characterization of an electron beam or an ion beam includes an electrical conducting disk of refractory material having a circumference, a center, and a Faraday cup assembly positioned to receive the electron beam or ion beam. At least one slit in the disk provides diagnostic characterization of the electron beam or ion beam. The at least one slit is located between the circumference and the center of the disk and includes a radial portion that is in radial alignment with the center and a portion that deviates from radial alignment with the center. The electron beam or ion beam is directed onto the disk and translated to the at least one slit wherein the electron beam or ion beam enters the at least one slit for providing diagnostic characterization of the electron beam or ion beam.

  13. Demonstrations Using a Fabry-Perot. I. Multiple-Slit Interference

    ERIC Educational Resources Information Center

    Roychoudhuri, Chandrasekhar

    1975-01-01

    Describes a demonstration technique for showing multiple-slit interference patterns with the use of a Fabry-Perot etalon and a laser beam. A simple derivation of the analytical expression for such fringes is presented. (Author/CP)

  14. Squeezing Millimeter Waves through a Single, Nanometer-wide, Centimeter-long Slit

    PubMed Central

    Chen, Xiaoshu; Park, Hyeong-Ryeol; Lindquist, Nathan C.; Shaver, Jonah; Pelton, Matthew; Oh, Sang-Hyun

    2014-01-01

    We demonstrate broadband non-resonant squeezing of terahertz (THz) waves through an isolated 2-nm-wide, 2-cm-long slit (aspect ratio of 107), representing a maximum intensity enhancement factor of one million. Unlike resonant nanogap structures, a single, effectively infinitely-long slit passes incident electromagnetic waves with no cutoff, enhances the electric field within the gap with a broad 1/f spectral response, and eliminates interference effects due to finite sample boundaries and adjacent elements. To construct such a uniform, isolated slit that is much longer than the millimeter-scale spot of a THz beam, we use atomic layer lithography to pattern vertical nanogaps in a metal film over an entire 4-inch wafer. We observe an increasing field enhancement as the slit width decreases from 20 nm to 2 nm, in agreement with numerical calculations. PMID:25342288

  15. Investigation on Multiple-Pulse Propulsion Performance for a Parabolic Nozzle with Inlet Slit

    NASA Astrophysics Data System (ADS)

    Wen, Ming; Hong, Yanji; Song, Junling

    2011-11-01

    The multiple-pulse impulse coupling coefficient Cm is lower than the single pulse one with the same laser parameters. It is always explained that air recovery in nozzle does not work on time. Three kinds of parabolic nozzles are employed to improve air recovery in the experiments and simulation. There exist inlet slits on side wall of them with width of 1 mm, 2 mm, respectively. The curves of thrust and the process of flow fluid field are presented to study the slit effects on Cm under 20 Hz pulse frequency. The results show: an inlet slit can accelerate the air breathing process in the nozzle and Cm for each pulse exhibits a little variation; the lower Cm is obtained due to the increasing energy loss by a larger size slit; the flat-roofed nozzle gets higher Cm than others.

  16. Transition from a spectrum filter to a polarizer in a metallic nano-slit array.

    PubMed

    Zhou, Jing; Guo, L Jay

    2014-01-09

    The transition from a spectrum filter (resonant transmission) to a polarizer (broadband transmission) for TM polarized light is observed in a metallic nano-slit array as period is decreased. A theoretical model is developed and shows that the spectrum filter behavior is caused by the coupled slit/grating resonance. With decreasing period, the slit resonance is decoupled from the grating resonance, which then dominates the transmission spectrum and broadens the transmission peak. With further reducing period, the slit resonance diminishes and the peak spectrum transforms to a broadband transmission. This effect is the basis for the operation of wire grid polarizers. The transition is explained by the change of the impedance to the incoming wave.

  17. 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.

  18. Multi-slit triode ion optical system with ballistic beam focusing

    SciTech Connect

    Davydenko, V. Amirov, V.; Gorbovsky, A.; Deichuli, P.; Ivanov, A.; Kolmogorov, A.; Kapitonov, V.; Mishagin, V.; Shikhovtsev, I.; Sorokin, A.; Stupishin, N.; Karpushov, A. N.; Smirnov, A.; Uhlemann, R.

    2016-02-15

    Multi-slit triode ion-optical systems with spherical electrodes are of interest for formation of intense focused neutral beams for plasma heating. At present, two versions of focusing multi-slit triode ion optical system are developed. The first ion optical system forms the proton beam with 15 keV energy, 140 A current, and 30 ms duration. The second ion optical system is intended for heating neutral beam injector of Tokamak Configuration Variable (TCV). The injector produces focused deuterium neutral beam with 35 keV energy, 1 MW power, and 2 s duration. In the later case, the angular beam divergence of the neutral beam is 20-22 mrad in the direction across the slits of the ion optical system and 12 mrad in the direction along the slits.

  19. Linear Accelerators

    NASA Astrophysics Data System (ADS)

    Sidorin, Anatoly

    2010-01-01

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  20. Linear Accelerators

    SciTech Connect

    Sidorin, Anatoly

    2010-01-05

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  1. Enhancing spatial resolution of digital holographic microscopy using speckle patterns generated from ring-slit apertures

    NASA Astrophysics Data System (ADS)

    Funamizu, Hideki; Chen, Tan Qin; Onodera, Yusei; Uozumi, Jun; Aizu, Yoshihisa

    2017-04-01

    In this study, we propose a method to enhance the spatial resolution of digital holographic microscopy with speckle-illumination. In this method, speckle patterns are generated from coherence light passing through ring-slit apertures instead of the most typical circular apertures, to obtain higher numerical aperture. The results show that a reconstructed image with the higher resolution is obtained using ring-slit apertures.

  2. Revisiting the Young's double slit experiment for background-free nonlinear Raman spectroscopy and microscopy.

    PubMed

    Gachet, David; Brustlein, Sophie; Rigneault, Hervé

    2010-05-28

    In the Young's double slit experiment, the spatial shift of the interference pattern projected onto a screen is directly related to the phase difference between the fields diffracted by the two slits. We apply this property to fields emitted by nonlinear processes and thus demonstrate background-free coherent anti-Stokes Raman scattering microscopy near an axial interface between a resonant and a nonresonant medium. This method is relevant to remove the nonresonant background in other coherent resonant processes.

  3. Myo9b is a key player in SLIT/ROBO-mediated lung tumor suppression.

    PubMed

    Kong, Ruirui; Yi, Fengshuang; Wen, Pushuai; Liu, Jianghong; Chen, Xiaoping; Ren, Jinqi; Li, Xiaofei; Shang, Yulong; Nie, Yongzhan; Wu, Kaichun; Fan, Daiming; Zhu, Li; Feng, Wei; Wu, Jane Y

    2015-11-03

    Emerging evidence indicates that the neuronal guidance molecule SLIT plays a role in tumor suppression, as SLIT-encoding genes are inactivated in several types of cancer, including lung cancer; however, it is not clear how SLIT functions in lung cancer. Here, our data show that SLIT inhibits cancer cell migration by activating RhoA and that myosin 9b (Myo9b) is a ROBO-interacting protein that suppresses RhoA activity in lung cancer cells. Structural analyses revealed that the RhoGAP domain of Myo9b contains a unique patch that specifically recognizes RhoA. We also determined that the ROBO intracellular domain interacts with the Myo9b RhoGAP domain and inhibits its activity; therefore, SLIT-dependent activation of RhoA is mediated by ROBO inhibition of Myo9b. In a murine model, compared with control lung cancer cells, SLIT-expressing cells had a decreased capacity for tumor formation and lung metastasis. Evaluation of human lung cancer and adjacent nontumor tissues revealed that Myo9b is upregulated in the cancer tissue. Moreover, elevated Myo9b expression was associated with lung cancer progression and poor prognosis. Together, our data identify Myo9b as a key player in lung cancer and as a ROBO-interacting protein in what is, to the best of our knowledge, a newly defined SLIT/ROBO/Myo9b/RhoA signaling pathway that restricts lung cancer progression and metastasis. Additionally, our work suggests that targeting the SLIT/ROBO/Myo9b/RhoA pathway has potential as a diagnostic and therapeutic strategy for lung cancer.

  4. Midbrain dopaminergic axons are guided longitudinally through the diencephalon by Slit/Robo signals.

    PubMed

    Dugan, James P; Stratton, Andrea; Riley, Hilary P; Farmer, W Todd; Mastick, Grant S

    2011-01-01

    Dopaminergic neurons from the ventral mesencephalon/diencephalon (mesodiencephalon) form vital pathways constituting the majority of the brain's dopamine systems. Mesodiencephalic dopaminergic (mdDA) neurons extend longitudinal projections anteriorly through the diencephalon, ascending toward forebrain targets. The mechanisms by which mdDA axons initially navigate through the diencephalon are poorly understood. Recently the Slit family of secreted axon guidance proteins, and their Robo receptors, have been identified as important guides for descending longitudinal axons. To test the potential roles of Slit/Robo guidance in ascending trajectories, we examined tyrosine hydroxylase-positive (TH+) projections from mdDA neurons in mutant mouse embryos. We found that mdDA axons grow out of and parallel to Slit-positive ventral regions within the diencephalon, and that subsets of the mdDA axons likely express Robo1 and possibly also Robo2. Slit2 was able to directly inhibit TH axon outgrowth in explant co-culture assays. The mdDA axons made significant pathfinding errors in Slit1/2 and Robo1/2 knockout mice, including spreading out in the diencephalon to form a wider tract. The wider tract resulted from a combination of invasion of the ventral midline, consistent with Slit repulsion, but also axons wandering dorsally, away from the ventral midline. Aberrant dorsal trajectories were prominent in Robo1 and Robo1/2 knockout mice, suggesting that an aspect of Robo receptor function is Slit-independent. These results indicate that Slit/Robo signaling is critical during the initial establishment of dopaminergic pathways, with roles in the dorsoventral positioning and precise pathfinding of these ascending longitudinal axons.

  5. Sensor based on Fano resonances of plane metamaterial with narrow slits

    NASA Astrophysics Data System (ADS)

    Huang, Wan-Xia; Guo, Juan-Juan; Wang, Mao-Sheng; Zhao, Guo-Ren

    2017-03-01

    The optical properties of a composite metamaterial composed of narrow slits and nano hole pairs have been investigated experimentally and numerically. The strength of the transmission peak originating from the interference between the coupled surface plasmon polaritons (SPP) of the narrow slit and the SPP modes of the hole array is modulated by the degree of symmetry breaking. Some SPP modes can be inhibited by controlling the spacer layer thickness. Our metamaterial has potential applications in sensing and weak signal detection.

  6. Use of a high-resolution camera (GoPro) for the slit lamp.

    PubMed

    Lee, Graham A; Shah, Peter

    2017-09-19

    The slit lamp enables a well-illuminated and magnified view of the eye. There have been previous imaging devices used for recording, however the quality of the stills and video is limited by cost. We present a relatively lower cost solution for the Haag-Streit slit lamp (Haag Streit AG, Switzerland) using a high definition camera, Hero5 Black (GoPro Inc., USA). This article is protected by copyright. All rights reserved.

  7. The pre-launch characterization of SIMBIO-SYS/VIHI imaging spectrometer for the BepiColombo mission to Mercury. I. Linearity, radiometry, and geometry calibrations.

    PubMed

    Filacchione, Gianrico; Capaccioni, Fabrizio; Altieri, Francesca; Carli, Cristian; Ficai Veltroni, Iacopo; Dami, Michele; Tommasi, Leonardo; Aroldi, Gianluca; Borrelli, Donato; Barbis, Alessandra; Baroni, Marco; Pastorini, Guia; Mugnuolo, Raffaele

    2017-09-01

    Before integration aboard European Space Agency BepiColombo mission to Mercury, the visible and near infrared hyperspectral imager underwent an intensive calibration campaign. We report in Paper I about the radiometric and linearity responses of the instrument including the optical setups used to perform them. Paper II [F. Altieri et al., Rev. Sci. Instrum. 88, 094503 (2017)] will describe complementary spectral response calibration. The responsivity is used to calculate the expected instrumental signal-to-noise ratio for typical observation scenarios of the BepiColombo mission around Mercury. A description is provided of the internal calibration unit that will be used to verify the relative response during the instrument's lifetime. The instrumental spatial response functions as measured along and across the spectrometer's slit direction were determined by means of spatial scans performed with illuminated test slits placed at the focus of a collimator. The dedicated optical setup used for these measurements is described together with the methods used to derive the instrumental spatial responses at different positions within the 3.5(°) field of view and at different wavelengths in the 0.4-2.0 μm spectral range. Finally, instrument imaging capabilities and Modulated Transfer Function are tested by using a standard mask as a target.

  8. Influence of blade profile of disc cutter on numerical simulation of the disc slitting process

    NASA Astrophysics Data System (ADS)

    Zeng, J.; Lu, J. B.; Yan, Q. S.; Li, S.

    2015-03-01

    The disc slitting machining experiments for electrical steel sheet were conducted to investigate the wear process of carbide alloy disc cutter and the slitting quality in the disc slitting process, and the blade contour shape of disc cutter in different slitting distance was measured by the surface profiler. A DEFORM-2D model, where the real blade profile or arc fitting profile was used as the blade contour of the cutter, was built to simulate the disc slitting process. Results show that the blade wear of disc cutter increases. The blade wear presents uneven in the side surface and cylindrical surface of the cutter, and the side wear is more serious with the increase of the slitting distance of electrical steel sheet. As the blade wear increases, the height of the rollover increases gradually, the height of the shear area increases at first and then decreases, but the height of the fracture area decreases at first and then increases. Compared with the arc fitting profile, the simulation surface morphology using the real blade profile is in good agreement with the experimental result. The variation of blade profile can change the distribution of the hydrostatic stress of sheet metal and the occurring and propagating of the crack, and the maximum hydrostatic stress can be used to estimate the change tendency of the fracture area.

  9. Vascularization and innervation of slits within polydimethylsiloxane sheets in the subcutaneous space of athymic nude mice.

    PubMed

    Gurlin, Rachel E; Keating, Mark T; Li, Shiri; Lakey, Jonathan Rt; de Feraudy, Sébastien; Shergill, Bhupinder S; Botvinick, Elliot L

    2017-01-01

    Success of cell therapy in avascular sites will depend on providing sufficient blood supply to transplanted tissues. A popular strategy of providing blood supply is to embed cells within a functionalized hydrogel implanted within the host to stimulate neovascularization. However, hydrogel systems are not always amenable for removal post-transplantation; thus, it may be advantageous to implant a device that contains cells while also providing access to the circulation so retrieval is possible. Here we investigate one instance of providing access to a vessel network, a thin sheet with through-cut slits, and determine if it can be vascularized from autologous materials. We compared the effect of slit width on vascularization of a thin sheet following subcutaneous implantation into an animal model. Polydimethylsiloxane sheets with varying slit widths (approximately 150, 300, 500, or 1500 µm) were fabricated from three-dimensional printed molds. Subcutaneous implantation of sheets in immunodeficient mice revealed that smaller slit widths have evidence of angiogenesis and new tissue growth, while larger slit widths contain native mature tissue squeezing into the space. Our results show that engineered slit sheets may provide a simple approach to cell transplantation by providing a prevascularized and innervated environment.

  10. Developmental Guidance of Embryonic Corneal Innervation: Roles of Semaphorin3A and Slit2

    PubMed Central

    Kubilus, James K.; Linsenmayer, Thomas F.

    2010-01-01

    The cornea is one of the most densely innervated structures of the body. In the developing chicken embryo, nerves from the ophthalmic trigeminal ganglion (OTG) innervate the cornea in a series of spatially and temporally regulated events. However, little is known concerning the signals that regulate these events. Here we have examined the involvement of the axon guidance molecules Semaphorin3A and Slit2, and their respective receptors, Neuropilin-1 and Robo2. Expression analyses of early corneas suggest an involvement of both Semaphorin3A and Slit2 in preventing nerves from entering the corneal stroma until the proper time (i.e., they serve as negative regulators), and analyses of their receptors support this conclusion. At later stages of development the expression of Semaphorin3A is again consistent with its serving as a negative regulator – this time for nerves entering the corneal epithelium. However, expression analyses of Robo2 at this stage raised the possibility that Slit2 had switched from a negative regulator to a positive regulator. In support of such a switch, functional analyses – by addition of recombinant Slit2 protein or immunoneutralization with a Slit2 antibody – showed that at an early stage Slit2 negatively regulates the outgrowth of nerves from the OTG, whereas at the later stage it positively regulated the growth of nerves by increasing nerve branching within the corneal epithelium. PMID:20471970

  11. A requirement for filopodia extension toward Slit during Robo-mediated axon repulsion.

    PubMed

    McConnell, Russell E; Edward van Veen, J; Vidaki, Marina; Kwiatkowski, Adam V; Meyer, Aaron S; Gertler, Frank B

    2016-04-25

    Axons navigate long distances through complex 3D environments to interconnect the nervous system during development. Although the precise spatiotemporal effects of most axon guidance cues remain poorly characterized, a prevailing model posits that attractive guidance cues stimulate actin polymerization in neuronal growth cones whereas repulsive cues induce actin disassembly. Contrary to this model, we find that the repulsive guidance cue Slit stimulates the formation and elongation of actin-based filopodia from mouse dorsal root ganglion growth cones. Surprisingly, filopodia form and elongate toward sources of Slit, a response that we find is required for subsequent axonal repulsion away from Slit. Mechanistically, Slit evokes changes in filopodium dynamics by increasing direct binding of its receptor, Robo, to members of the actin-regulatory Ena/VASP family. Perturbing filopodium dynamics pharmacologically or genetically disrupts Slit-mediated repulsion and produces severe axon guidance defects in vivo. Thus, Slit locally stimulates directional filopodial extension, a process that is required for subsequent axonal repulsion downstream of the Robo receptor.

  12. Are snakes particles or waves? Scattering of a limbless locomotor through a single slit

    NASA Astrophysics Data System (ADS)

    Qian, Feifei; Dai, Jin; Gong, Chaohui; Choset, Howie; Goldman, Daniel

    Droplets on vertically vibrated fluid surfaces can walk and diffract through a single slit by a pilot wave hydrodynamic interaction [Couder, 2006; Bush, 2015]. Inspired by the correspondence between emergent macroscale dynamics and phenomena in quantum systems, we tested if robotic snakes, which resemble wave packets, behave emergently like particles or waves when interacting with an obstacle. In lab experiments and numerical simulations we measured how a multi-module snake-like robot swam through a single slit. We controlled the snake undulation gait as a fixed serpenoid traveling wave pattern with varying amplitude and initial phase, and we examined the snake trajectory as it swam through a slit with width d. Robot trajectories were straight before interaction with the slit, then exited at different scattering angle θ after the interaction due to a complex interaction of the body wave with the slit. For fixed amplitude and large d, the snake passed through the slit with minimal interaction and theta was ~ 0 . For sufficiently small d, θ was finite and bimodally distributed, depending on the initial phase. For intermediate d, θ was sensitive to initial phase, and the width of the distribution of θ increased with decreasing d.

  13. Vascularization and innervation of slits within polydimethylsiloxane sheets in the subcutaneous space of athymic nude mice

    PubMed Central

    Gurlin, Rachel E; Keating, Mark T; Li, Shiri; Lakey, Jonathan RT; de Feraudy, Sébastien; Shergill, Bhupinder S; Botvinick, Elliot L

    2017-01-01

    Success of cell therapy in avascular sites will depend on providing sufficient blood supply to transplanted tissues. A popular strategy of providing blood supply is to embed cells within a functionalized hydrogel implanted within the host to stimulate neovascularization. However, hydrogel systems are not always amenable for removal post-transplantation; thus, it may be advantageous to implant a device that contains cells while also providing access to the circulation so retrieval is possible. Here we investigate one instance of providing access to a vessel network, a thin sheet with through-cut slits, and determine if it can be vascularized from autologous materials. We compared the effect of slit width on vascularization of a thin sheet following subcutaneous implantation into an animal model. Polydimethylsiloxane sheets with varying slit widths (approximately 150, 300, 500, or 1500 µm) were fabricated from three-dimensional printed molds. Subcutaneous implantation of sheets in immunodeficient mice revealed that smaller slit widths have evidence of angiogenesis and new tissue growth, while larger slit widths contain native mature tissue squeezing into the space. Our results show that engineered slit sheets may provide a simple approach to cell transplantation by providing a prevascularized and innervated environment. PMID:28228933

  14. The Amyloid Precursor Protein Is a Conserved Receptor for Slit to Mediate Axon Guidance

    PubMed Central

    Li, Hongmei; Mutlu, Sena A.; Bowser, Devon A.; Wang, Meng C.

    2017-01-01

    Abstract The amyloid precursor protein (APP) is a receptor-like membrane protein. Although APP processing and β-amyloid production play a central role in Alzheimer’s disease (AD) pathogenesis, the physiological function of APP remains elusive. Here, we identify APP as a novel receptor for Slit that mediates axon guidance and neural circuit formation. APP deficiency abolishes the Slit repulsive effect in a 3D olfactory explant culture, consistent with its callosal projection deficit in vivo and reminiscent of Slit loss. Inactivation of APP ortholog APL-1 in Caenorhabditis elegans results in pioneer axon mistargeting and genetic analysis places APL-1 in the SLT-1 (Slit)/SAX-3 (Robo) repulsive pathway. Slit binds to APP through the E1 domain, which triggers APP ectodomain shedding and recruitment of the intracellular FE65 and Pak1 complex and associated Rac1 GTPase activation. Our study establishes APP as a novel receptor for Slit ligand mediating axon guidance and neural circuit formation. PMID:28785723

  15. Measuring the residual stress in dental composites using a ring slitting method.

    PubMed

    Park, Jeong Won; Ferracane, Jack L

    2005-09-01

    The objective of this experiment was to employ the ring slitting method for the measurement of the residual stress (RS) produced in dental composite materials after polymerization. This study was designed to determine the effect of slitting and measuring time on the residual stress. Rings were made in a split brass mold from three composites (Z100/3MESPE; Herculite/Kerr; Heliomolar/Ivoclar) and cured in a Triad II (Dentsply). Two points were scribed, and the rings were slit at either 1 h (Early-group) or 24 h (Delayed-group) after curing the composite. The change in the distance between the scribed points was measured using an image analyzer system at both 1 and 24 h after slitting. From the measured change, circumferential RS was calculated and statistically analyzed with ANOVA/Tukey's (P<0.05). The degree of conversion of each composite at 1 and 24 h was measured with FTIR and analyzed using Student's t-test (P<0.05). In general, the residual stress (range=0.42-2.84 MPa) was highest for Z100 and lowest for Heliomolar, but this depended upon the test conditions. The early cut (1 h slitting), 24 h measurement groups showed the highest residual stress values. This study, describes a ring slitting method to measure residual stress generated in dental composites during and after curing. The stress of composite can be affected by the cutting and measurement time.

  16. Slit-check dams for the control of debris flow

    NASA Astrophysics Data System (ADS)

    Armanini, Aronne; Larcher, Michele

    2017-04-01

    Debris flows are paroxysmal events that mobilize, alongside water, huge quantities of sediment in a very short time, then with both solid and liquid huge discharges, possibly exceeding the capacity of the current torrent restoration works. In this respect, the climate change forcing cannot be ignored. In the majority of urbanized areas, that are generally the most vulnerable, there is often not enough space to create channelling works able to let the volumes pass through without overflowing. The simplest, less expensive and most sustainable solution consists in reducing the peak solid discharge by creating storage areas upstream of the settlements, typically upstream of the alluvial fans, allowing for reduced works of canalization, that are compatible with the constraints imposed by the urbanization. The general idea consists in storing a part of the flowing solids during the peak of the hydrograph and releasing it in a successive phase or during minor floods. For this purpose, and in order to optimize the solid peak discharge reduction, it is necessary that properly designed open-check dams, capable of inducing a significative sedimentation of the solid discharge only when this exceeds a design-threshold value, control the deposition basins. A correct design of the check dam is crucial in order to induce the sedimentation in the right amount and at the right moment: a too early sedimentation might fill the volume before the peak, like in the case of close-check dams, while a too weak sedimentation might not use the whole available volume. In both cases, the channelling works might not be sufficient to let all the flow pass through, compromising the safety of the settlement. To avoid this inconvenience, we propose the use of slit-check dams, whose efficiency has already been proved for bed load. Check dams are often designed only on the base of the designer's experience. Besides, even today it is often believed that the filtering effect of open check dams is

  17. Single-stepper soft x-ray source for step-and-scan tools

    NASA Astrophysics Data System (ADS)

    Piestrup, Melvin A.; Powell, Michael W.; Mrowka, Stanley; Lombardo, Louis W.; Chase, Michael B.; Cremer, J. Theodore; Maruyama, Xavier K.

    1997-07-01

    As a synchrotron equivalent, this paper presents a single- stepper, soft-x-ray source which offers high brightness, high collimation (less than 20 mr global and less than 2 mr local), modest operating vacuum, excellent spectrum and moderate cost. The x-rays are generated by a process called transition radiation (TR). Electrons of moderate energy (e.g. 17 - 100 MeV) pass through thin-metal foils producing a forward- directed cone of x-rays whose photon energies can be between 0.5 and 3 keV. The optimum radiator consists of many thin- metal foils, e.g. beryllium, which are separated by vacuum. The x-ray wavelength an be optimized for highest photoresist sensitivity, e.g. 1.4 nm. A computer simulation shows that for beam-shaping (slit formation) and collimation, a single grazing-angle optic transforms the radiator cone into a slit (5 mm by 26 mm) in the 1X wafer image plane, having an energy density of 15 - 60 mJ/cm2. This slit is then scanned for dose uniformity. In a proof-of-principle experiment, an apparatus utilizing a Au-coated grazing-angle optic was used to focus transition radiation to a slit (7 mm by 16 mm) in the image plane at 631 mm from the optic and 881 mm from the TR radiator. Intensity variation across the longitudinal direction (approximately 10 mm) of the slit was less than 5%.

  18. Plasmonic interferometry: Probing launching dipoles in scanning-probe plasmonics

    NASA Astrophysics Data System (ADS)

    Mollet, Oriane; Bachelier, Guillaume; Genet, Cyriaque; Huant, Serge; Drezet, Aurélien

    2014-03-01

    We develop a semi-analytical method for analyzing surface plasmon interferometry using scanning-probe tips as SP launchers. We apply our approach to Young double-hole interferometry experiments in a scanning tunneling microscope discussed recently in the literature as well as to new experiments—reported here—with an aperture near-field scanning optical microscope source positioned near a ring-like aperture slit in a thick gold film. In both experimental configurations, the agreement between experiments and model is very good. Our work reveals the role of the launching dipole orientations and magnetic versus electric dipole contributions to the interference imaging process. It also stresses the different orientations of the effective dipoles associated with the two different scanning-probe techniques.

  19. Full-range k-domain linearization in spectral-domain optical coherence tomography

    PubMed Central

    Jeon, Mansik; Kim, Jeehyun; Jung, Unsang; Lee, Changho; Jung, Woonggyu; Boppart, Stephen A.

    2011-01-01

    A full-bandwidth k-domain linearization method for spectral-domain optical coherence tomography (SD-OCT) is demonstrated. The method uses information of the wavenumber–pixel-position provided by a translating-slit-based wavelength filter. For calibration purposes, the filter is placed either after a broadband source or at the end of the sample path, and the filtered spectrum with a narrowed line width (~0.5 nm) is incident on a line-scan camera in the detection path. The wavelength-swept spectra are co-registered with the pixel positions according to their central wavelengths, which can be automatically measured with an optical spectrum analyzer. For imaging, the method does not require a filter or a software recalibration algorithm; it simply resamples the OCT signal from the detector array without employing rescaling or interpolation methods. The accuracy of k-linearization is maximized by increasing the k-linearization order, which is known to be a crucial parameter for maintaining a narrow point-spread function (PSF) width at increasing depths. The broadening effect is studied by changing the k-linearization order by undersampling to search for the optimal value. The system provides more position information, surpassing the optimum without compromising the imaging speed. The proposed full-range k-domain linearization method can be applied to SD-OCT systems to simplify their hardware/software, increase their speed, and improve the axial image resolution. The experimentally measured width of PSF in air has an FWHM of 8 μm at the edge of the axial measurement range. At an imaging depth of 2.5 mm, the sensitivity of the full-range calibration case drops less than 10 dB compared with the uncompensated case. PMID:21394187

  20. Differentiation of epithelial foot processes and filtration slits: sequential appearance of occluding junctions, epithelial polyanion, and slit membranes in developing glomeruli.

    PubMed

    Reeves, W; Caulfield, J P; Farquhar, M G

    1978-08-01

    The visceral glomerular epithelium of immature glomeruli from newborn rats was examined in order to determine the sequence of events that occurs during differentiation of foot processes and filtration slits. Four different stages of glomerular development were defined: vesicle, S-shaped body, developing capillary loop, and maturing stages. During the vesicle stage, the precursor cells of the glomerular and tubular epithelium are joined by occluding junctions at their apices. During the S-shaped body stage, the tubular and parietal visceral glomerular epithelium differentiate, and the occluding zonulae remain along the presumptive tubule lumen and Bowman's space, respectively. With the appearance of capillary loops the parietal and tubular junctions maintain this arrangement, but the junctions of the visceral epithelium are seen at various levels along the lateral cell margins, suggesting that they migrate along the lateral cell surfaces from apex to base. Initially, broad epithelial processes cover the entire outer aspect of the developing basement membrane. After junctional migration interdigitation of epithelial processes is seen, and the processes are joined by focal occluding junctions (maculae or fasciae). With more elaborate interdigitation, fewer and fewer intercellular spaces are closed by occluding junctions, the junctions become less and less extensive, and normal slit architecture with foot processes bridged by slit membranes predominate. Colloidal iron staining (i.e., epithelial polyanion) is first detected along the lateral epithelial cell surfaces early in the capillary loop stage and becomes concentrated along their basal cell surfaces facing the basement membrane at about the same time as interdigitation is occurring. Therefore, facing the basement membrane at about the same time as interdigitation is occurring. Therefore, sialoproteins appear on the epithelial cell surfaces prior to the development of foot processes and slits. This finding is in

  1. Arm CT scan

    MedlinePlus

    CAT scan - arm; Computed axial tomography scan - arm; Computed tomography scan - arm; CT scan - arm ... your provider should weigh this risk against the benefits of getting a correct diagnosis for a medical ...

  2. Pioneer midbrain longitudinal axons navigate using a balance of Netrin attraction and Slit repulsion

    PubMed Central

    2014-01-01

    Background Longitudinal axons grow parallel to the embryonic midline to connect distant regions of the central nervous system. Previous studies suggested that repulsive midline signals guide pioneer longitudinal axons by blocking their entry into the floor plate; however, the role of midline attractants, and whether attractant signals may cooperate with repulsive signals, remains unclear. In this study we investigated the navigation of a set of pioneer longitudinal axons, the medial longitudinal fasciculus, in mouse embryos mutant for the Netrin/Deleted in Colorectal Cancer (DCC) attractants, and for Slit repellents, as well as the responses of explanted longitudinal axons in vitro. Results In mutants for Netrin1 chemoattractant or DCC receptor signaling, longitudinal axons shifted away from the ventral midline, suggesting that Netrin1/DCC signals act attractively to pull axons ventrally. Analysis of mutants in the three Slit genes, including Slit1/2/3 triple mutants, suggest that concurrent repulsive Slit/Robo signals push pioneer axons away from the ventral midline. Combinations of mutations between the Netrin and Slit guidance systems provided genetic evidence that the attractive and repulsive signals balance against each other. This balance is demonstrated in vitro using explant culture, finding that the cues can act directly on longitudinal axons. The explants also reveal an unexpected synergy of Netrin1 and Slit2 that promotes outgrowth. Conclusions These results support a mechanism in which longitudinal trajectories are positioned by a push-pull balance between opposing Netrin and Slit signals. Our evidence suggests that longitudinal axons respond directly and simultaneously to both attractants and repellents, and that the combined signals constrain axons to grow longitudinally. PMID:25056828

  3. Digital adaptive optics line-scanning confocal imaging system

    PubMed Central

    Liu, Changgeng; Kim, Myung K.

    2015-01-01

    Abstract. A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea. PMID:26140334

  4. Digital adaptive optics line-scanning confocal imaging system.

    PubMed

    Liu, Changgeng; Kim, Myung K

    2015-01-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  5. Digital adaptive optics line-scanning confocal imaging system

    NASA Astrophysics Data System (ADS)

    Liu, Changgeng; Kim, Myung K.

    2015-11-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack-Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  6. Continuum Mechanics Based Bi-linear Shear Deformable Shell Element Using Absolute Nodal Coordinate Formulation

    DTIC Science & Technology

    2014-03-07

    the convergent solution in the case of the continuum mechanics based bi- linear shear deformable ANCF shell element. 5.3 Slit Annular Plate Subjected...UNCLASSIFIED: Distribution Statement A. Approved for public release. #24515 CONTINUUM MECHANICS BASED BI- LINEAR SHEAR DEFORMABLE SHELL ELEMENT...MAR 2014 2. REPORT TYPE Technical Report 3. DATES COVERED 07-01-2014 to 04-03-2014 4. TITLE AND SUBTITLE CONTINUUM MECHANICS BASED BI- LINEAR

  7. Ultrafast CT scanning of an oak log for internal defects

    Treesearch

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

    1989-01-01

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

  8. Fast scanning mode and its realization in a scanning acoustic microscope

    SciTech Connect

    Ju Bingfeng; Bai Xiaolong; Chen Jian

    2012-03-15

    The scanning speed of the two-dimensional stage dominates the efficiency of mechanical scanning measurement systems. This paper focused on a detailed scanning time analysis of conventional raster and spiral scan modes and then proposed two fast alternative scanning modes. Performed on a self-developed scanning acoustic microscope (SAM), the measured images obtained by using the conventional scan mode and fast scan modes are compared. The total scanning time is reduced by 29% of the two proposed fast scan modes. It will offer a better solution for high speed scanning without sacrificing the system stability, and will not introduce additional difficulties to the configuration of scanning measurement systems. They can be easily applied to the mechanical scanning measuring systems with different driving actuators such as piezoelectric, linear motor, dc motor, and so on. The proposed fast raster and square spiral scan modes are realized in SAM, but not specially designed for it. Therefore, they have universal adaptability and can be applied to other scanning measurement systems with two-dimensional mechanical scanning stages, such as atomic force microscope or scanning tunneling microscope.

  9. Fast scanning mode and its realization in a scanning acoustic microscope.

    PubMed

    Ju, Bing-Feng; Bai, Xiaolong; Chen, Jian

    2012-03-01

    The scanning speed of the two-dimensional stage dominates the efficiency of mechanical scanning measurement systems. This paper focused on a detailed scanning time analysis of conventional raster and spiral scan modes and then proposed two fast alternative scanning modes. Performed on a self-developed scanning acoustic microscope (SAM), the measured images obtained by using the conventional scan mode and fast scan modes are compared. The total scanning time is reduced by 29% of the two proposed fast scan modes. It will offer a better solution for high speed scanning without sacrificing the system stability, and will not introduce additional difficulties to the configuration of scanning measurement systems. They can be easily applied to the mechanical scanning measuring systems with different driving actuators such as piezoelectric, linear motor, dc motor, and so on. The proposed fast raster and square spiral scan modes are realized in SAM, but not specially designed for it. Therefore, they have universal adaptability and can be applied to other scanning measurement systems with two-dimensional mechanical scanning stages, such as atomic force microscope or scanning tunneling microscope.

  10. Broadening of fast-beam spectral lines due to diffraction at the entrance slit of a spectrometer.

    NASA Technical Reports Server (NTRS)

    Leavitt, J. A.; Stoner, J. O., Jr.

    1972-01-01

    Experimental and theoretical demonstration of the necessity to take into account the effects of diffraction at a spectrometer's entrance slit in adjusting the spectrometer for observation of fast-beam spectral lines under conditions of minimum linewidth. An approximate expression is obtained for the optimum entrance slit width to be used in order to avoid the pronounced broadening of the spectral lines that occurs for very narrow entrance slits.

  11. Analysis of slit function errors in single-shot coherent anti-Stokes Raman spectroscopy (CARS) in practical combustors

    SciTech Connect

    Heneghan, S.P.; Vangsness, M.D. )

    1991-09-01

    The temperature determined by a single-shot coherent anti-Stokes Raman spectroscopy (CARS) system is directly related to the half width at half maximum of the instrument slit function. Therefore, an accurate knowledge of the instrument slit function is necessary to determine temperature with CARS. However, in turbulent systems, the input slits of the spectrometer may be removed in order to guarantee signal throughput and establish the necessary dynamic range. In this case, the physical input slits of the spectrometer are replaced with apparent slits created by focussing the input beams near the entrance plane of the spectrometer. The slit function will then depend on the physical relationship among all of the optical components, the probe volume, and the dispersive performance of the spectrometer and detector, as well as the optical path through density and temperature gradients which may not be invariant in a turbulent system. The presence of high temperatures and turbulence levels can effect the size of the CARS signal origin and the optical path, and as a result, the slit function is not invariant. Ignoring these changes can result in large root mean square temperatures (decreased precision) as well as mean temperature errors. The variability of the slit width can be accounted for on a shot-to-shot basis by using a two parameter (HWHM of the slit function and temperature) fitting routine. For temperatures greater than 1200 K there is convergence on a best curve implying both a temperature and a slit width. This method can be used alone or in concert with various weighting schemes to improve the precision. There are two major advantages gained by allowing the slit function to vary in a CARS system: (a) it allows an increase in the precision; (b) it allows temperatures to be calculated without the assumption that the slit function does not change with temperature or turbulence or position within the flame.

  12. Characterization of the optical non-linear response of the (E)-4-(4-dimetylaminophenyl) but-3-en-2-one and (E)-4-(4-nitrophenyl) but-3-en-2-one by Z-Scan

    NASA Astrophysics Data System (ADS)

    Rodriguez, K.; Pérez, A.; Racedo, F.

    2017-01-01

    We presents the study carried out by the technique Z-Scan, to analyse the nonlinear optical properties of (E)-4-(4-dimetylaminophenyl) but-3-en-2-one and (E)-4-(4-nitrophenyl) but-3-en-2-one, diluted in Ethyl Acetate with concentration levels of [0.02M, 0.08M, 0.23M] and [0.0047M, 0.013M, 0.041M] respectively. The measurements were performed using a Nd:YAG laser emitting at 532nm, for samples with Leff =1mm thickness, and a automated scanning of 10cm symmetric to the lens focus, the iris diameter was 1mm, the samples were also characterized by an UV-Vis Spectroscopy. We calculated the nonlinear refractive index (η2), the nonlinear absorption coefficient (β) and the the third-order nonlinear optical susceptibility (χ3) of the two researched compounds. The results show a combination of thermal response and nonlinear self-defocusing and self-focusing, which make their application interesting as new optoelectronic materials.

  13. Rapid-scan EPR imaging

    NASA Astrophysics Data System (ADS)

    Eaton, Sandra S.; Shi, Yilin; Woodcock, Lukas; Buchanan, Laura A.; McPeak, Joseph; Quine, Richard W.; Rinard, George A.; Epel, Boris; Halpern, Howard J.; Eaton, Gareth R.

    2017-07-01

    In rapid-scan EPR the magnetic field or frequency is repeatedly scanned through the spectrum at rates that are much faster than in conventional continuous wave EPR. The signal is directly-detected with a mixer at the source frequency. Rapid-scan EPR is particularly advantageous when the scan rate through resonance is fast relative to electron spin relaxation rates. In such scans, there may be oscillations on the trailing edge of the spectrum. These oscillations can be removed by mathematical deconvolution to recover the slow-scan absorption spectrum. In cases of inhomogeneous broadening, the oscillations may interfere destructively to the extent that they are not visible. The deconvolution can be used even when it is not required, so spectra can be obtained in which some portions of the spectrum are in the rapid-scan regime and some are not. The technology developed for rapid-scan EPR can be applied generally so long as spectra are obtained in the linear response region. The detection of the full spectrum in each scan, the ability to use higher microwave power without saturation, and the noise filtering inherent in coherent averaging results in substantial improvement in signal-to-noise relative to conventional continuous wave spectroscopy, which is particularly advantageous for low-frequency EPR imaging. This overview describes the principles of rapid-scan EPR and the hardware used to generate the spectra. Examples are provided of its application to imaging of nitroxide radicals, diradicals, and spin-trapped radicals at a Larmor frequency of ca. 250 MHz.

  14. Regeneration and maintenance of the planarian midline is regulated by a slit orthologue.

    PubMed

    Cebrià, Francesc; Guo, Tingxia; Jopek, Jessica; Newmark, Phillip A

    2007-07-15

    Several families of evolutionarily conserved axon guidance cues orchestrate the precise wiring of the nervous system during embryonic development. The remarkable plasticity of freshwater planarians provides the opportunity to study these molecules in the context of neural regeneration and maintenance. Here we characterize a homologue of the Slit family of guidance cues from the planarian Schmidtea mediterranea. Smed-slit is expressed along the planarian midline, in both dorsal and ventral domains. RNA interference (RNAi) targeting Smed-slit results in the collapse of many newly regenerated tissues at the midline; these include the cephalic ganglia, ventral nerve cords, photoreceptors, and the posterior digestive system. Surprisingly, Smed-slit RNAi knockdown animals also develop morphologically distinguishable, ectopic neural structures near the midline in uninjured regions of intact and regenerating planarians. These results suggest that Smed-slit acts not only as a repulsive cue required for proper midline formation during regeneration but that it may also act to regulate the behavior of neural precursors at the midline in intact planarians.

  15. Role of Slit and Robo proteins in the development of dopaminergic neurons.

    PubMed

    Cornide-Petronio, María Eugenia; Barreiro-Iglesias, Antón

    2013-01-01

    Dopamine plays a number of important roles in the nervous system and the dopaminergic system is affected in several brain disorders. It is therefore of great interest to study the axonal guidance systems that specifically participate in the correct establishment of dopaminergic projections during development and possibly during regenerative processes. In recent years, several reports have shown that Slits and their Robo receptors control the growth of longitudinal (both ascending and descending) mesodiencephalic dopaminergic axons to their appropriate target areas. In vitro studies have shown that Slit1, 2 and 3 are potent repellents of dopamine neurite extension. In vivo studies using both mice and zebrafish mutants for Slits and Robos have shown that Slits and Robos control the lateral and dorsoventral positioning of dopaminergic longitudinal projections during early development. In the present review, we aimed to compile the existing knowledge from both in vitro and in vivo studies on the role of Slit and Robo proteins in the development of dopaminergic neurons as a basis for future studies.

  16. Final report on LDRD project : biodiesel production from vegetable oils using slit-channel reactors.

    SciTech Connect

    Kalu, E. Eric; Chen, Ken Shuang

    2008-01-01

    This report documents work done for a late-start LDRD project, which was carried out during the last quarter of FY07. The objective of this project was to experimentally explore the feasibility of converting vegetable (e.g., soybean) oils to biodiesel by employing slit-channel reactors and solid catalysts. We first designed and fabricated several slit-channel reactors with varying channel depths, and employed them to investigate the improved performance of slit-channel reactors over traditional batch reactors using a NaOH liquid catalyst. We then evaluated the effectiveness of several solid catalysts, including CaO, ZnO, MgO, ZrO{sub 2}, calcium gluconate, and heteropolyacid or HPA (Cs{sub 2.5}H{sub 0.5}PW{sub 12}O{sub 40}), for catalyzing the soybean oil-to-biodiesel transesterification reaction. We found that the slit-channel reactor performance improves as channel depth decreases, as expected; and the conversion efficiency of a slit-channel reactor is significantly higher when its channel is very shallow. We further confirmed CaO as having the highest catalytic activity among the solid catalysts tested, and we demonstrated for the first time calcium gluconate as a promising solid catalyst for converting soybean oil to biodiesel, based on our preliminary batch-mode conversion experiments.

  17. Simulation of femtosecond ``double-slit'' experiments for a chromophore in a dissipative environment

    NASA Astrophysics Data System (ADS)

    Gelin, M. F.; Tanimura, Y.; Domcke, W.

    2013-12-01

    We performed simulations of the prototypical femtosecond "double-slit" experiment with strong pulsed laser fields for a chromophore in solution. The chromophore is modeled as a system with two electronic levels and a single Franck-Condon active underdamped vibrational mode. All other (intra- and inter-molecular) vibrational modes are accounted for as a thermal bath. The system-bath coupling is treated in a computationally accurate manner using the hierarchy equations of motion approach. The double-slit signal is evaluated numerically exactly without invoking perturbation theory in the matter-field interaction. We show that the strong-pulse double-slit signal consists of a superposition of N-wave-mixing (N = 2, 4, 6…) responses and can be split into population and coherence contributions. The former reveals the dynamics of vibrational wave packets in the ground state and the excited electronic state of the chromophore, while the latter contains information on the dephasing of electronic coherences of the chromophore density matrix. We studied the influence of heat baths with different coupling strengths and memories on the double-slit signal. Our results show that the double-slit experiment performed with strong (nonperturbative) pulses yields substantially more information on the photoinduced dynamics of the chromophore than the weak-pulse experiment, in particular, if the bath-induced dephasings are fast.

  18. Quantitative trait gene Slit2 positively regulates murine hematopoietic stem cell numbers

    PubMed Central

    Waterstrat, Amanda; Rector, Kyle; Geiger, Hartmut; Liang, Ying

    2016-01-01

    Hematopoietic stem cells (HSC) demonstrate natural variation in number and function. The genetic factors responsible for the variations (or quantitative traits) are largely unknown. We previously identified a gene whose differential expression underlies the natural variation of HSC numbers in C57BL/6 (B6) and DBA/2 (D2) mice. We now report the finding of another gene, Slit2, on chromosome 5 that also accounts for variation in HSC number. In reciprocal chromosome 5 congenic mice, introgressed D2 alleles increased HSC numbers, whereas B6 alleles had the opposite effect. Using gene array and quantitative polymerase chain reaction, we identified Slit2 as a quantitative trait gene whose expression was positively correlated with the number of HSCs. Ectopic expression of Slit2 not only increased the number of the long-term colony forming HSCs, but also enhanced their repopulation capacity upon transplantation. Therefore, Slit2 is a novel quantitative trait gene and a positive regulator of the number and function of murine HSCs. This finding suggests that Slit2 may be a potential therapeutic target for the effective in vitro and in vivo expansion of HSCs without compromising normal hematopoiesis. PMID:27503415

  19. Structural correlates of mechanosensory transduction and adaptation in identified neurons of spider slit sensilla.

    PubMed

    Höger, U; Seyfarth, E A

    2001-11-01

    We used isolated but functionally intact preparations of the lyriform slit-sense organ VS-3 from the leg of the spider, Cupiennius salei Keys, to examine the role of prominent fine-structural elements for mechanosensory transduction and adaptation. Slit sensilla act as strain sensors in the cuticular exoskeleton; each slit is innervated by two mechanosensitive neurons. Punctate mechanical deformation at four points along the dendrites demonstrated that mechanical excitability is confined to membrane sites at the extreme dendrite tips that are enclosed by cuticular slit structures. Depletion of microtubules in VS-3 neurons by prolonged mechanical stimulation and application of 5 mmol l(-1) colchicine did not disrupt the generation of a receptor potential. Hence, putative gating mechanisms of the mechanically activated membrane channels at the dendrite tips appear to be largely independent of microtubular structures. The discrete adaptation pattern in each of the two partner neurons, rapidly adapting versus slowly adapting, did not depend on the distinct mode of dendrite attachment to cuticular slit structures, and even persisted in isolated neurons after their dendrite tips and auxiliary structures were lost. We suggest that the two discrete adaptation patterns are based on intrinsic differences in the action potential encoding process rather than differences in stimulus transformation or mechanotransduction.

  20. Center Finding Algorithm on slit mask point source for IGRINS (Immersion GRating INfrared Spectrograph)

    NASA Astrophysics Data System (ADS)

    Lee, Hye-In; Pak, Soojong; Lee, Jae-Joon; Mace, Gregory N.; Jaffe, Daniel Thomas

    2017-06-01

    We developed an observation control software for the IGRINS (Immersion Grating Infrared Spectrograph) silt-viewing camera module, which points the astronomical target onto the spectroscopy slit and sends tracking feedbacks to the telescope control system (TCS). The point spread function (PSF) image is not following symmetric Gaussian profile. In addition, bright targets are easily saturated and shown as a donut shape. It is not trivial to define and find the center of the asymmetric PSF especially when most of the stellar PSF falls inside the slit. We made a center balancing algorithm (CBA) which derives the expected center position along the slit-width axis by referencing the stray flux ratios of both upper and lower sides of the slit. We compared accuracies of the CBA and those of a two-dimensional Gaussian fitting (2DGA) through simulations in order to evaluate the center finding algorithms. These methods were then verified with observational data. In this poster, we present the results of our tests and suggest a new algorithm for centering targets in the slit image of a spectrograph.