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Sample records for bright field cell

  1. Hybrid bright-field and hologram imaging of cell dynamics

    Science.gov (United States)

    Byeon, Hyeokjun; Lee, Jaehyun; Doh, Junsang; Lee, Sang Joon

    2016-09-01

    Volumetric observation is essential for understanding the details of complex biological phenomena. In this study, a bright-field microscope, which provides information on a specific 2D plane, and a holographic microscope, which provides information spread over 3D volumes, are integrated to acquire two complementary images simultaneously. The developed system was successfully applied to capture distinct T-cell adhesion dynamics on inflamed endothelial layers, including capture, rolling, crawling, transendothelial migration, and subendothelial migration.

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

    Science.gov (United States)

    Bradbury, Laura; Wan, Justin W L

    2010-01-01

    Automatic segmentation of bright-field cell images is important to cell biologists, but difficult to complete due to the complex nature of the cells in bright-field images (poor contrast, broken halo, missing boundaries). Standard approaches such as level set segmentation and active contours work well for fluorescent images where cells appear as round shape, but become less effective when optical artifacts such as halo exist in bright-field images. In this paper, we present a robust segmentation method which combines the spectral and k-means clustering techniques to locate cells in bright-field images. This approach models an image as a matrix graph and segment different regions of the image by computing the appropriate eigenvectors of the matrix graph and using the k-means algorithm. We illustrate the effectiveness of the method by segmentation results of C2C12 (muscle) cells in bright-field images. PMID:21096019

  3. Bright-field cell image segmentation by principal component pursuit with an Ncut penalization

    Science.gov (United States)

    Chen, Yuehuan; Wan, Justin W. L.

    2015-03-01

    Segmentation of cells in time-lapse bright-field microscopic images is crucial in understanding cell behaviours for oncological research. However, the complex nature of the cells makes it difficult to segment cells accurately. Furthermore, poor contrast, broken cell boundaries and the halo artifact pose additional challenges to this problem. Standard segmentation techniques such as edged-based methods, watershed, or active contours result in poor segmentation. Other existing methods for bright-field images cannot provide good results without localized segmentation steps. In this paper, we present two robust mathematical models to segment bright-field cells automatically for the entire image. These models treat cell image segmentation as a background subtraction problem, which can be formulated as a Principal Component Pursuit (PCP) problem. Our first segmentation model is formulated as a PCP with nonnegative constraints. We exploit the sparse component of the PCP solution for identifying the cell pixels. However, there is no control on the quality of the sparse component and the nonzero entries can scatter all over the image, resulting in a noisy segmentation. The second model is an improvement of the first model by combining PCP with spectral clustering. Seemingly unrelated approaches, we combine the two techniques by incorporating normalized-cut in the PCP as a measure for the quality of the segmentation. These two models have been applied to a set of C2C12 cells obtained from bright-field microscopy. Experimental results demonstrate that the proposed models are effective in segmenting cells from bright-field images.

  4. Cell motility dynamics: a novel segmentation algorithm to quantify multi-cellular bright field microscopy images.

    Directory of Open Access Journals (Sweden)

    Assaf Zaritsky

    Full Text Available Confocal microscopy analysis of fluorescence and morphology is becoming the standard tool in cell biology and molecular imaging. Accurate quantification algorithms are required to enhance the understanding of different biological phenomena. We present a novel approach based on image-segmentation of multi-cellular regions in bright field images demonstrating enhanced quantitative analyses and better understanding of cell motility. We present MultiCellSeg, a segmentation algorithm to separate between multi-cellular and background regions for bright field images, which is based on classification of local patches within an image: a cascade of Support Vector Machines (SVMs is applied using basic image features. Post processing includes additional classification and graph-cut segmentation to reclassify erroneous regions and refine the segmentation. This approach leads to a parameter-free and robust algorithm. Comparison to an alternative algorithm on wound healing assay images demonstrates its superiority. The proposed approach was used to evaluate common cell migration models such as wound healing and scatter assay. It was applied to quantify the acceleration effect of Hepatocyte growth factor/scatter factor (HGF/SF on healing rate in a time lapse confocal microscopy wound healing assay and demonstrated that the healing rate is linear in both treated and untreated cells, and that HGF/SF accelerates the healing rate by approximately two-fold. A novel fully automated, accurate, zero-parameters method to classify and score scatter-assay images was developed and demonstrated that multi-cellular texture is an excellent descriptor to measure HGF/SF-induced cell scattering. We show that exploitation of textural information from differential interference contrast (DIC images on the multi-cellular level can prove beneficial for the analyses of wound healing and scatter assays. The proposed approach is generic and can be used alone or alongside traditional

  5. Automatic cell detection in bright-field microscopy for microbeam irradiation studies

    International Nuclear Information System (INIS)

    Automatic cell detection in bright-field illumination microscopy is challenging due to cells’ inherent optical properties. Applications including individual cell microbeam irradiation demand minimisation of additional cell stressing factors, so contrast-enhancing fluorescence microscopy should be avoided. Additionally, the use of optically non-homogeneous substrates amplifies the problem. This research focuses on the design of a method for automatic cell detection on polypropylene substrate, suitable for microbeam irradiation. In order to fulfil the relative requirements, the Harris corner detector was employed to detect apparent cellular features. These features-corners were clustered based on a dual-clustering technique according to the density of their distribution across the image. Weighted centroids were extracted from the clusters of corners and constituted the targets for irradiation. The proposed method identified more than 88% of the 1,738 V79 Chinese hamster cells examined. Moreover, a processing time of 2.6 s per image fulfilled the requirements for a near real-time cell detection-irradiation system. (paper)

  6. Automatic cell detection in bright-field microscopy for microbeam irradiation studies

    Science.gov (United States)

    Georgantzoglou, A.; Merchant, M. J.; Jeynes, J. C. G.; Wéra, A.-C.; Kirkby, K. J.; Kirkby, N. F.; Jena, R.

    2015-08-01

    Automatic cell detection in bright-field illumination microscopy is challenging due to cells’ inherent optical properties. Applications including individual cell microbeam irradiation demand minimisation of additional cell stressing factors, so contrast-enhancing fluorescence microscopy should be avoided. Additionally, the use of optically non-homogeneous substrates amplifies the problem. This research focuses on the design of a method for automatic cell detection on polypropylene substrate, suitable for microbeam irradiation. In order to fulfil the relative requirements, the Harris corner detector was employed to detect apparent cellular features. These features-corners were clustered based on a dual-clustering technique according to the density of their distribution across the image. Weighted centroids were extracted from the clusters of corners and constituted the targets for irradiation. The proposed method identified more than 88% of the 1,738 V79 Chinese hamster cells examined. Moreover, a processing time of 2.6 s per image fulfilled the requirements for a near real-time cell detection-irradiation system.

  7. Super-resolved 3-D imaging of live cells organelles from bright-field photon transmission micrographs

    CERN Document Server

    Rychtarikova, Renata; Shi, Kevin; Malakhova, Daria; Machacek, Petr; Smaha, Rebecca; Urban, Jan; Stys, Dalibor

    2016-01-01

    Current biological and medical research is aimed at obtaining a detailed spatiotemporal map of a live cell's interior to describe and predict cell's physiological state. We present here an algorithm for complete 3-D modelling of cellular structures from a z-stack of images obtained using label-free wide-field bright-field light-transmitted microscopy. The method visualizes 3-D objects with a volume equivalent to the area of a camera pixel multiplied by the z-height. The computation is based on finding pixels of unchanged intensities between two consecutive images of an object spread function. These pixels represent strongly light-diffracting, light-absorbing, or light-emitting objects. To accomplish this, variables derived from R\\'{e}nyi entropy are used to suppress camera noise. Using this algorithm, the detection limit of objects is only limited by the technical specifications of the microscope setup--we achieve the detection of objects of the size of one camera pixel. This method allows us to obtain 3-D re...

  8. Dependence on the incident light power of the internal electric fields in a GaAs p-i-n solar cell according to bright photoreflectance spectroscopy

    Science.gov (United States)

    Jo, Hyun-Jun; Mun, Young Hee; Kim, Jong Su; Lee, Sang Jun

    2016-07-01

    Bright photoreflectance (BPR) spectroscopy at room temperature is used to examine the internal electric fields in a GaAs p-i-n solar cell for their dependence on the incident light power. Electric fields are observed at 30 µW and 100 µW of incident light. With increasing power, the strengths of the two electric fields are reduced due to the photovoltage effect. The electric field observed at 30 µW is assigned to the p-i interface, which is close to the surface. The other electric field is due to the i-n interface because the incident light penetrates deeper as the light power is increased. The electric field strength of 35.6 kV/cm at the p-i interface is lower than that of 42.9 kV/cm at the i-n interface at 500 µW of light power because the photovoltage effect is proportional to the number of photo-generated carriers, which is reduced as the distance from the surface increases. When the incident light power is similar to the excitation beam power, the electric fields at the p-i interface are saturated.

  9. Annular bright and dark field imaging of soft materials

    International Nuclear Information System (INIS)

    Here polyethylene, as an example of an important soft material, was studied by STEM annular bright and dark field. The contrast as function of the probe size/shape and the detector collection angle are discussed. The results are compared to conventional bright field transmission electron microscopy, electron energy filtered imaging and energy dispersive spectroscopy mapping. Annular bright and dark field gave a higher contrast than conventional transmission and analytical mapping techniques

  10. Hubble ultra deep field object surface brightness variation

    International Nuclear Information System (INIS)

    The technique of adjacent pixel brightness variation in log scale was applied to ultra deep field objects captured by the Hubble telescope. The local surface brightness fluctuation has a Gaussian-like distribution implying a random accretion of material, with collisions, as a random-walk motion. The larger fluctuation of log brightness in the mid to outer regions of some galaxies is consistent with the presence of dark matter. The absence of such fluctuation enhancement in two i-drop candidates at z ∼ 3 may mean that some dark matter is the result of nucleosynthesis in the evolution process. Large fluctuation in the B+V bands in contrast to the i+z band near the center in an i-drop candidate at z ∼ 3 was interpreted to be an AGN center. The distribution average shifts towards zero for more spiral galaxies, signifying the use of local surface brightness fluctuation distribution as a morphology parameter

  11. An in-house developed annular bright field detection system

    International Nuclear Information System (INIS)

    Annular bright field (ABF) detectors have been developed in the last few years allowing the direct imaging of low-Z atoms from oxygen down to hydrogen. These types of detectors are now available as standard attachments for the latest generation of top-end electron microscopes. However these systems cannot always be installed in previous generation microscopes. In this paper we report the preliminary results of an in-house implementation of a ABF detection system on a CEOS aberration corrected JEOL 2200FS STEM. This has been obtained by exploiting the standard BF detector coupled with a high vacuum compatible, X-ray tight and retractable shadowing mechanism. This results in the acquisition of near zero-angle scattered electrons with inner collection semi-angle from 2.0 mrad to 23 mrad and outer semi-angle in the range from 3.0 mrad to 35 mrad. The characteristics and performances of this ABF detection system are discussed

  12. Direct imaging of phase objects enables conventional deconvolution in bright field light microscopy.

    Directory of Open Access Journals (Sweden)

    Carmen Noemí Hernández Candia

    Full Text Available In transmitted optical microscopy, absorption structure and phase structure of the specimen determine the three-dimensional intensity distribution of the image. The elementary impulse responses of the bright field microscope therefore consist of separate absorptive and phase components, precluding general application of linear, conventional deconvolution processing methods to improve image contrast and resolution. However, conventional deconvolution can be applied in the case of pure phase (or pure absorptive objects if the corresponding phase (or absorptive impulse responses of the microscope are known. In this work, we present direct measurements of the phase point- and line-spread functions of a high-aperture microscope operating in transmitted bright field. Polystyrene nanoparticles and microtubules (biological polymer filaments serve as the pure phase point and line objects, respectively, that are imaged with high contrast and low noise using standard microscopy plus digital image processing. Our experimental results agree with a proposed model for the response functions, and confirm previous theoretical predictions. Finally, we use the measured phase point-spread function to apply conventional deconvolution on the bright field images of living, unstained bacteria, resulting in improved definition of cell boundaries and sub-cellular features. These developments demonstrate practical application of standard restoration methods to improve imaging of phase objects such as cells in transmitted light microscopy.

  13. Graphical Methods for Quantifying Macromolecules through Bright Field Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hang; DeFilippis, Rosa Anna; Tlsty, Thea D.; Parvin, Bahram

    2008-08-14

    Bright ?eld imaging of biological samples stained with antibodies and/or special stains provides a rapid protocol for visualizing various macromolecules. However, this method of sample staining and imaging is rarely employed for direct quantitative analysis due to variations in sample fixations, ambiguities introduced by color composition, and the limited dynamic range of imaging instruments. We demonstrate that, through the decomposition of color signals, staining can be scored on a cell-by-cell basis. We have applied our method to Flbroblasts grown from histologically normal breast tissue biopsies obtained from two distinct populations. Initially, nuclear regions are segmented through conversion of color images into gray scale, and detection of dark elliptic features. Subsequently, the strength of staining is quanti?ed by a color decomposition model that is optimized by a graph cut algorithm. In rare cases where nuclear signal is significantly altered as a result of samplepreparation, nuclear segmentation can be validated and corrected. Finally, segmented stained patterns are associated with each nuclear region following region-based tessellation. Compared to classical non-negative matrix factorization, proposed method (i) improves color decomposition, (ii) has a better noise immunity, (iii) is more invariant to initial conditions, and (iv) has a superior computing performance

  14. Dual-color ultrasensitive bright-field RNA in situ hybridization with RNAscope.

    Science.gov (United States)

    Wang, Hongwei; Su, Nan; Wang, Li-Chong; Wu, Xingyong; Bui, Son; Nielsen, Allissa; Vo, Hong-Thuy; Luo, Yuling; Ma, Xiao-Jun

    2014-01-01

    In situ hybridization (ISH) techniques have been important to the study of gene expression signatures in cells and tissues. The ability to detect multiple targets simultaneously is especially valuable, since it allows dissecting gene expression of distinct cell types with precise cellular and subcellular resolution within morphological context. Recently, we have reported using a novel dual-color ultrasensitive bright-field RNA in situ hybridization for detection of clonally restricted immunoglobulin light chain mRNA expression in B cell lymphomas. Here, we present detailed protocols of RNAscope 2-Plex assays for FFPE tissue sections. The protocols describe the tissue preparation, pretreatment, probe hybridization, signal amplification, visualization, and analysis, as well as emphasize the critical steps for ensuring successful staining.

  15. CD4+CD25bright T cells in human intestinal lamina propria as regulatory cells.

    Science.gov (United States)

    Makita, Shin; Kanai, Takanori; Oshima, Shigeru; Uraushihara, Koji; Totsuka, Teruji; Sawada, Taisuke; Nakamura, Tetsuya; Koganei, Kazutaka; Fukushima, Tsuneo; Watanabe, Mamoru

    2004-09-01

    It is well known that immune responses in the intestine remain in a state of controlled inflammation, suggesting that not only active suppression by regulatory T cells plays an important role in the normal intestinal homeostasis, but also its dysregulation leads to the development of inflammatory bowel disease. In this study, we demonstrate that the CD4(+)CD25(bright) T cells reside in the human intestinal lamina propria (LP) and functionally retain regulatory activities. All human LP CD4(+) T cells regardless of CD25 expression constitutively expressed CTLA-4, glucocorticoid-induced TNFR family-related protein, and Foxp3 and proliferate poorly. Although LP CD4(+)CD25(-) T cells showed an activated and anergic/memory phenotype, they did not retain regulatory activity. In LP CD4(+)CD25(+) T cells, however, cells expressing CD25 at high levels (CD4(+)CD25(bright)) suppressed the proliferation and various cytokine productions of CD4(+)CD25(-) T cells. LP CD4(+)CD25(bright) T cells by themselves produced fewer amounts of IL-2, IFN-gamma, and IL-10. Interestingly, LP CD4(+)CD25(bright) T cells with regulatory T activity were significantly increased in patients with active inflammatory bowel disease. These results suggest that CD4(+)CD25(bright) T cells found in the normal and inflamed intestinal mucosa selectively inhibit the host immune response and therefore may contribute to the intestinal immune homeostasis. PMID:15322172

  16. Solar velocity field determined tracking coronal bright points

    Science.gov (United States)

    Brajša, R.; Sudar, D.; Skokić, I.; Saar, S. H.; Žic, T.

    Preliminary data from Atmospheric Imaging Assembly (AIA) instrumenton board Solar Dynamics Observatory (SDO) satellite were used to determine solar differential rotation and related phenomena. A segmentation algorithm, which uses multiple AIA channels in search for intensity enhancements in EUV and X-ray parts of the spectrum compared to the background intensity, was applied to obtain positional information of coronal bright points (CBPs). More than 60000 position measurements of more than 10000 identified CBPs from the period 1 - 2 January 2011 were analyzed. Rotational and meridional velocities were determined by tracking identified CBPs and various filters were used to exclude erroneous results. Also, proper motions of CBPs were calculated from rotation velocity residuals and meridional velocities. Proper motions of CBPs were investigated using a random walk model and the diffusion constant was calculated. These results were compared with the previous ones obtained by other instruments and methods (especially with the SOHO-EIT and Hinode data) and a striking agreement of the obtained diffusion constant with results from other studies was found.

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

    Institute of Scientific and Technical Information of China (English)

    Zhonghua Hao(郝中华); Jinsong Liu(刘劲松)

    2003-01-01

    Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton's peak intensity is derived, and some corresponding properties of the self-deflection process are figured out.

  18. Organization Theory: Bright Prospects for a Permanently Failing Field

    OpenAIRE

    Heugens, Pursey

    2008-01-01

    textabstractOrganization theory is a paradoxical field of scientific inquiry. It has struggled for more than fifty years to develop a unified theory of organizational effectiveness under girded by a coherent set of assumptions, and it has thus far failed to produce one. Yet, by other standards it is simultaneously a tremendously successful field. It has great intellectual mobilizing powers and its publications - journals as well as books - are highly esteemed. In this address I attempt to unr...

  19. Organization Theory: Bright Prospects for a Permanently Failing Field

    NARCIS (Netherlands)

    P.P.M.A.R. Heugens (Pursey)

    2008-01-01

    textabstractOrganization theory is a paradoxical field of scientific inquiry. It has struggled for more than fifty years to develop a unified theory of organizational effectiveness under girded by a coherent set of assumptions, and it has thus far failed to produce one. Yet, by other standards it is

  20. Simultaneous fluorescence and high-resolution bright-field imaging with aberration correction over a wide field-of-view with Fourier ptychographic microscopy (FPM) (Conference Presentation)

    Science.gov (United States)

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-03-01

    We present a method to acquire both fluorescence and high-resolution bright-field images with correction for the spatially varying aberrations over a microscope's wide field-of-view (FOV). First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff frequency of the microscope objective lens. At the same time, FPM algorithm is able to leverage on the redundancy within the set of acquired FPM bright-field images to estimate the microscope aberrations, which usually deteriorate in regions further away from the FOV's center. Second, the procedure acquires a raw wide-FOV fluorescence image within the same setup. Lack of moving parts allows us to use the FPM-estimated aberration map to computationally correct for the aberrations in the fluorescence image through deconvolution. Overlaying the aberration-corrected fluorescence image on top of the high-resolution bright-field image can be done with accurate spatial correspondence. This can provide means to identifying fluorescent regions of interest within the context of the sample's bright-field information. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of ~18.

  1. Quantitative measurement of brightness from living cells in the presence of photodepletion.

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Hur

    Full Text Available The brightness of fluorescently labeled proteins provides an excellent marker for identifying protein interactions in living cells. Quantitative interpretation of brightness, however, hinges on a detailed understanding of the processes that affect the signal fluctuation of the fluorescent label. Here, we focus on the cumulative influence of photobleaching on brightness measurements in cells. Photobleaching within the finite volume of the cell leads to a depletion of the population of fluorescently labeled proteins with time. The process of photodepletion reduces the fluorescence signal which biases the analysis of brightness data. Our data show that even small reductions in the signal can introduce significant bias into the analysis of the data. We develop a model that quantifies the bias and introduce an analysis method that accurately determines brightness in the presence of photodepletion as verified by experiments with mammalian and yeast cells. In addition, photodepletion experiments with the fluorescent protein EGFP reveal the presence of a photoconversion process, which leads to a marked decrease in the brightness of the EGFP protein. We also identify conditions where the effect of EGFP's photoconversion on brightness experiments can be safely ignored.

  2. Quantitative Measurement of Brightness from Living Cells in the Presence of Photodepletion

    Science.gov (United States)

    Berk, Serkan; Angert, C. Isaac; Chen, Yan; Mueller, Joachim D.

    2014-01-01

    The brightness of fluorescently labeled proteins provides an excellent marker for identifying protein interactions in living cells. Quantitative interpretation of brightness, however, hinges on a detailed understanding of the processes that affect the signal fluctuation of the fluorescent label. Here, we focus on the cumulative influence of photobleaching on brightness measurements in cells. Photobleaching within the finite volume of the cell leads to a depletion of the population of fluorescently labeled proteins with time. The process of photodepletion reduces the fluorescence signal which biases the analysis of brightness data. Our data show that even small reductions in the signal can introduce significant bias into the analysis of the data. We develop a model that quantifies the bias and introduce an analysis method that accurately determines brightness in the presence of photodepletion as verified by experiments with mammalian and yeast cells. In addition, photodepletion experiments with the fluorescent protein EGFP reveal the presence of a photoconversion process, which leads to a marked decrease in the brightness of the EGFP protein. We also identify conditions where the effect of EGFP's photoconversion on brightness experiments can be safely ignored. PMID:24820174

  3. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope

    CERN Document Server

    Suran, Swathi; Raghavan, Srinivasan; Varma, Manoj M

    2015-01-01

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of ...

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

    Institute of Scientific and Technical Information of China (English)

    刘劲松; 郝中华

    2003-01-01

    The self-deflection of a bright solitary beam can be controlled by a dark solitary beam via a parametric coupling effect between the bright and dark solitary beams in a separate bright-dark spatial soliton pair supported by an unbiased series photorefractive crystal circuit. The spatial shift of the bright solitary beam centre as a function of the input intensity of the dark solitary beam (p) is investigated by taking into account the higher-order space charge field in the dynamics of the bright solitary beam via both numerical and perturbation methods under steady-state conditions.The deflection amount (△s0), defined as the value of the spatial shift at the output surface of the crystal, is a monotonic and nonlinear function ofp. When p is weak or strong enough, △s0 is, in fact, unchanged with ρ, whereas △s0 increases or decreases monotonically withp in a middle range of p. The corresponding variation range (δs) depends strongly on the value of the input intensity of the bright solitary beam (r). There are some peak and valley values in the curve of δs versus r under some conditions. When p increases, the bright solitary beam can scan toward both the direction same as and opposite to the crystal's c-axis. Whether the direction is the same as or opposite to the c-axis depends on the parameter values and configuration of the crystal circuit, as well as the value of r. Some potential applications are discussed.

  5. Portable, Battery-Operated, Low-Cost, Bright Field and Fluorescence Microscope

    OpenAIRE

    Miller, Andrew R.; Davis, Gregory L.; Oden, Z. Maria; Razavi, Mohamad Reza; Fateh, Abolfazl; Ghazanfari, Morteza; Abdolrahimi, Farid; Poorazar, Shahin; Sakhaie, Fatemeh; Olsen, Randall J.; Bahrmand, Ahmad Reza; Pierce, Mark C.; Edward A. Graviss; Richards-Kortum, Rebecca

    2010-01-01

    This study describes the design and evaluation of a portable bright-field and fluorescence microscope that can be manufactured for $240 USD. The microscope uses a battery-operated LED-based flashlight as the light source and achieves a resolution of 0.8 µm at 1000× magnification in fluorescence mode. We tested the diagnostic capability of this new instrument to identify infections caused by the human pathogen, Mycobacterium tuberculosis. Sixty-four direct, decontaminated, and serially diluted...

  6. Bright and stable CdSe/CdS@SiO2 nanoparticles suitable for long term cell labeling

    OpenAIRE

    Aubert, Tangi; Wassmuth, Daniel; Soenen, Stefaan; Braeckmans, Kevin; Hens, Zeger

    2014-01-01

    Semiconductor quantum dots (QDs) constitute very promising candidates as light emitters for numerous applications in the field of biotechnology, including cell labeling, in vivo imaging and diagnostics.[1] For such applications, semiconductor QDs represent an attractive alternative to classic organic fluorophores as they exhibit a higher brightness thanks to their large absorption cross-sections and high photoluminescence quantum yields. Nevertheless, QDs usually suffer from higly oxidative e...

  7. Near-Field Analysis of Bright and Dark Modes on Plasmonic Metasurfaces Showing Extraordinary Suppressed Transmission

    CERN Document Server

    Dobmann, Sabine; Ploss, Daniel; Peschel, Ulf

    2014-01-01

    Plasmonic metasurfaces are investigated that consist of a sub wavelength line pattern in an ultrathin (~ 10 nm) silver film, designed for extraordinarily suppressed transmission (EOST) in the visible spectral range. Measurements with a near-field scanning optical microscope (NSOM) demonstrate that far field irradiation creates resonant excitations of antenna like (bright) modes that are localized on the metal ridges. In contrast, bound (dark) surface plasmon polaritons (SPPs) launched from an NSOM tip propagate well across the metasurface, preferentially perpendicular to the grating lines.

  8. On the relationship between G-band bright point dynamics and their magnetic field strengths

    CERN Document Server

    Yang, Yunfei; Ji, Kaifan; Feng, Song; Deng, Hui; Wang, Feng; Lin, Jiaben

    2016-01-01

    G-band bright points (GBPs) are regarded as good manifestations of magnetic flux concentrations. We aim to investigate the relationship between the dynamic properties of GBPs and their longitudinal magnetic field strengths. High spatial and temporal resolution observations were recorded simultaneously with G-band filtergrams and Narrow-band Filter Imager (NFI) Stokes I and V images with Hinode /Solar Optical Telescope. The GBPs are identified and tracked in the G-band images automatically, and the corresponding longitudinal magnetic field strength of each GBP is extracted from the calibrated NFI magnetograms by a point-to-point method. After categorizing the GBPs into five groups by their longitudinal magnetic field strengths, we analyze the dynamics of GBPs of each group. The results suggest that with increasing longitudinal magnetic field strengths of GBPs correspond to a decrease in their horizontal velocities and motion ranges as well as by showing more complicated motion paths. This suggests that magneti...

  9. Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images.

    Science.gov (United States)

    Watson, Jeffrey R; Gainer, Christian F; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G Michael; Anton, Rein; Romanowski, Marek

    2015-10-01

    Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures.

  10. Dispersal of G-band bright points at different longitudinal magnetic field strengths

    CERN Document Server

    Yunfei, Yang; Song, Feng; Hui, Deng; Feng, Wang; Jiaben, Lin

    2015-01-01

    G-band bright points (GBPs) are thought to be the foot-points of magnetic flux tubes. The aim of this paper is to investigate the relation between the diffusion regimes of GBPs and the associated longitudinal magnetic field strengths. Two high resolution observations of different magnetized environments were acquired with the Hinode/Solar Optical Telescope. Each observation was recorded simultaneously with G-band filtergrams and Narrow-band Filter Imager (NFI) Stokes I and V images. GBPs are identified and tracked automatically, and then categorized into several groups by their longitudinal magnetic field strengths, which are extracted from the calibrated NFI magnetograms using a point-by-point method. The Lagrangian approach and the distribution of diffusion indices approach are adopted separately to explore the diffusion regime of GBPs for each group. It is found that the values of diffusion index and diffusion coefficient both decrease exponentially with the increasing longitudinal magnetic field strengths...

  11. Controlling the transition of bright and dark states via scanning dressing field

    Science.gov (United States)

    Li, Peiying; Zheng, Huaibin; Zhang, Yiqi; Sun, Jia; Li, Changbiao; Huang, Gaoping; Zhang, Zhaoyang; Li, Yuanyuan; Zhang, Yanpeng

    2013-03-01

    We report the transitions between the bright and dark states of singly-dressed four-wave mixing (FWM) and doubly-dressed FWMs, and the corresponding probe transmissions by scanning the dressing field frequency detuning in a five-level atomic system. Moreover, doubly-dressed six-wave mixing with avoided-crossing plots and triple-dressed eight-wave mixing with the comparison of scanning probe field and dressing field are studied. Such controlled transitions of the nonlinear optical signals can be realizable not only in atomic vapors but also in solid medium. The investigations maybe have potential applications in optical communication, quantum information processing and optoelectronic devices, and maybe also provide a sensitive probe method to study the dressing effect.

  12. Bright-Field Imaging and Optical Coherence Tomography of the Mouse Posterior Eye.

    Science.gov (United States)

    Krebs, Mark P; Xiao, Mei; Sheppard, Keith; Hicks, Wanda; Nishina, Patsy M

    2016-01-01

    Noninvasive live imaging has been used extensively for ocular phenotyping in mouse vision research. Bright-field imaging and optical coherence tomography (OCT) are two methods that are particularly useful for assessing the posterior mouse eye (fundus), including the retina, retinal pigment epithelium, and choroid, and are widely applied due to the commercial availability of sophisticated instruments and software. Here, we provide a guide to using these approaches with an emphasis on post-acquisition image processing using Fiji, a bundled version of the Java-based public domain software ImageJ. A bright-field fundus imaging protocol is described for acquisition of multi-frame videos, followed by image registration to reduce motion artifacts, averaging to reduce noise, shading correction to compensate for uneven illumination, filtering to improve image detail, and rotation to adjust orientation. An OCT imaging protocol is described for acquiring replicate volume scans, with subsequent registration and averaging to yield three-dimensional datasets that show reduced motion artifacts and enhanced detail. The Fiji algorithms used in these protocols are designed for batch processing and are freely available. The image acquisition and processing approaches described here may facilitate quantitative phenotyping of the mouse eye in drug discovery, mutagenesis screening, and the functional cataloging of mouse genes by individual laboratories and large-scale projects, such as the Knockout Mouse Phenotyping Project and International Mouse Phenotyping Consortium.

  13. Next Generation High Brightness Electron Beams From Ultra-High Field Cryogenic Radiofrequency Photocathode Sources

    CERN Document Server

    Rosenzweig, J B; Dolgashev, V; Emma, C; Fukusawa, A; Li, R; Limborg, C; Maxson, J; Musumeci, P; Nause, A; Pakter, R; Pompili, R; Roussel, R; Spataro, B; Tantawi, S

    2016-01-01

    Recent studies of the performance of radio-frequency (RF) copper structures operated at cryogenic temperatures have shown a dramatic increase in the maximum surface electric field that may be reached. We propose to utilize this development to enable a new generation of photoinjectors operated at cryogenic temperatures that may attain, through enhancement of the launch field at the photocathode by a factor of four, well over an order of magnitude increase in peak electron beam brightness. We present detailed studies of the beam dynamics associated with such a system, concentrating on an emittance-compensated S-band photoinjector that may directly substitute that of the LCLS X-ray free-electron laser. We show in this case that the increase in brightness leads directly to a factor of two reduction in gain length, with attendant increase in X-ray radiative efficiency. Extreme low emittance scenarios obtained at low operating charge, appropriate for dramatically pushing performance limits of ultrafast electron dif...

  14. Influence of the phase effect on gradient-based and statistics-based focus measures in bright field microscopy.

    Science.gov (United States)

    Schoell, S; Mualla, F; Sommerfeldt, B; Steidl, S; Maier, A; Buchholz, R; Hornegger, J

    2014-05-01

    Autofocusing is essential to high throughput microscopy and live cell imaging and requires reliable focus measures. Phase objects such as separated single Chinese hamster ovary cells are almost invisible at the optical focus position in bright field microscopy images. Because of the phase effect, defocused images of phase objects have more contrast. In this paper, we show that widely used focus measures exhibit an untypical behaviour for such images. In the case of homogeneous cells, that is, when most cells tend to lie in the same focal plane, both gradient-based and statistics-based focus measures tend to have a local minimum instead of a global maximum at the optical focus position. On the other hand, if images show inhomogeneous cells, gradient-based focus measures tend to yield typical focus curves, whereas statistics-based focus measures deliver curves similar to the case of homogeneous cells. These results were interpreted using the equation describing the phase effect and patch-wise analysis of the focus curves. Bioprocess engineering experts are also influenced by the phase effect. Forty-four focus positions selected by them led to the conclusion that they prefer to look at defocused images instead of those at the optical focus. PMID:24611652

  15. The discovery of seven extremely low surface brightness galaxies in the field of the nearby spiral galaxy M101

    CERN Document Server

    Merritt, Allison; Abraham, Roberto

    2014-01-01

    Dwarf satellite galaxies are a key probe of dark matter and of galaxy formation on small scales and of the dark matter halo masses of their central galaxies. They have very low surface brightness, which makes it difficult to identify and study them outside of the Local Group. We used a low surface brightness-optimized telescope, the Dragonfly Telephoto Array, to search for dwarf galaxies in the field of the massive spiral galaxy M101. We identify seven large, low surface brightness objects in this field, with effective radii of \\(10 - 30\\) arcseconds and central surface brightnesses of \\(\\mu_{g} \\sim 25.5 - 27.5\\) mag arcsec\\(^{-2}\\). Given their large apparent sizes and low surface brightnesses, these objects would likely be missed by standard galaxy searches in deep fields. Assuming the galaxies are dwarf satellites of M101, their absolute magnitudes are in the range \\(-11.6 \\lesssim M_{V} \\lesssim -9.3\\) and their effective radii are \\(350\\) pc \\(-\\) \\(1.3\\) kpc. Their radial surface brightness profiles ar...

  16. Blue Laser Imaging-Bright Improves Endoscopic Recognition of Superficial Esophageal Squamous Cell Carcinoma

    Science.gov (United States)

    Tomie, Akira; Yagi, Nobuaki; Kitae, Hiroaki; Majima, Atsushi; Horii, Yusuke; Kitaichi, Tomoko; Onozawa, Yuriko; Suzuki, Kentaro; Kimura-Tsuchiya, Reiko; Okayama, Tetsuya; Kamada, Kazuhiro; Katada, Kazuhiro; Uchiyama, Kazuhiko; Ishikawa, Takeshi; Takagi, Tomohisa; Naito, Yuji; Itoh, Yoshito

    2016-01-01

    Background/Aims. The aim of this study was to evaluate the endoscopic recognition of esophageal squamous cell carcinoma (ESCC) using four different methods (Olympus white light imaging (O-WLI), Fujifilm white light imaging (F-WLI), narrow band imaging (NBI), and blue laser imaging- (BLI-) bright). Methods. We retrospectively analyzed 25 superficial ESCCs that had been examined using the four different methods. Subjective evaluation was provided by three endoscopists as a ranking score (RS) of each image based on the ease of detection of the cancerous area. For the objective evaluation we calculated the color difference scores (CDS) between the cancerous and noncancerous areas with each of the four methods. Results. There was no difference between the mean RS of O-WLI and F-WLI. The mean RS of NBI was significantly higher than that of O-WLI and that of BLI-bright was significantly higher than that of F-WLI. Moreover, the mean RS of BLI-bright was significantly higher than that of NBI. Furthermore, in the objective evaluation, the mean CDS of BLI-bright was significantly higher than that of O-WLI, F-WLI, and NBI. Conclusion. The recognition of superficial ESCC using BLI-bright was more efficacious than the other methods tested both subjectively and objectively.

  17. Rapidly Rotating, X-ray Bright Stars in the Kepler Field

    CERN Document Server

    Howell, Steve B; Boyd, Padi; Smith, Krista Lynne; Gelino, Dawn

    2016-01-01

    We present Kepler light curves and optical spectroscopy of twenty X-ray bright stars located in the Kepler field of view. The stars, spectral type FK, show evidence for rapid rotation including chromospheric activity 100 times or more above the Sun at maximum and flaring behavior in their light curves. Eighteen of our objects appear to be (sub)giants and may belong to the class of FK Com variables, that is evolved rapidly spinning single stars with no excretion disk and high levels of chromospheric activity. Such stars are rare and are likely the result of W UMa binary mergers, a process believed to produce the FK Com class of variable and their descendants. The FK Com stage, including the presence of an excretion disk, is short-lived but leads to longer-lived stages consisting of single, rapidly rotating evolved (sub)giants with high levels of stellar activity.

  18. Spatially Multiplexed Micro-Spectrophotometry in Bright Field Mode for Thin Film Characterization.

    Science.gov (United States)

    Pini, Valerio; Kosaka, Priscila M; Ruz, Jose J; Malvar, Oscar; Encinar, Mario; Tamayo, Javier; Calleja, Montserrat

    2016-01-01

    Thickness characterization of thin films is of primary importance in a variety of nanotechnology applications, either in the semiconductor industry, quality control in nanofabrication processes or engineering of nanoelectromechanical systems (NEMS) because small thickness variability can strongly compromise the device performance. Here, we present an alternative optical method in bright field mode called Spatially Multiplexed Micro-Spectrophotometry that allows rapid and non-destructive characterization of thin films over areas of mm² and with 1 μm of lateral resolution. We demonstrate an accuracy of 0.1% in the thickness characterization through measurements performed on four microcantilevers that expand an area of 1.8 mm² in one minute of analysis time. The measured thickness variation in the range of few tens of nm translates into a mechanical variability that produces an error of up to 2% in the response of the studied devices when they are used to measure surface stress variations. PMID:27338398

  19. Bright-field imaging of compound semiconductors using aberration-corrected scanning transmission electron microscopy

    Science.gov (United States)

    Aoki, Toshihiro; Lu, Jing; McCartney, Martha R.; Smith, David J.

    2016-09-01

    This study reports the observation of six different zincblende compound semiconductors in [110] projection using large-collection-angle bright-field (LABF) imaging with an aberration-corrected scanning transmission electron microscope. Phase contrast is completely suppressed when the collection semi-angle is set equal to the convergence semi-angle and there are no reversals in image contrast with changes in defocus or thickness. The optimum focus for imaging closely separated pairs of atomic columns (‘dumbbells’) is unique and easily recognized, and the positions of atomic columns occupied by heavier atoms always have darker intensity than those occupied by lighter atoms. Thus, the crystal polarity of compound semiconductors can be determined unambiguously. Moreover, it is concluded that the LABF imaging mode will be highly beneficial for studying other more complicated heterostructures at the atomic scale.

  20. Spatially Multiplexed Micro-Spectrophotometry in Bright Field Mode for Thin Film Characterization

    Directory of Open Access Journals (Sweden)

    Valerio Pini

    2016-06-01

    Full Text Available Thickness characterization of thin films is of primary importance in a variety of nanotechnology applications, either in the semiconductor industry, quality control in nanofabrication processes or engineering of nanoelectromechanical systems (NEMS because small thickness variability can strongly compromise the device performance. Here, we present an alternative optical method in bright field mode called Spatially Multiplexed Micro-Spectrophotometry that allows rapid and non-destructive characterization of thin films over areas of mm2 and with 1 μm of lateral resolution. We demonstrate an accuracy of 0.1% in the thickness characterization through measurements performed on four microcantilevers that expand an area of 1.8 mm2 in one minute of analysis time. The measured thickness variation in the range of few tens of nm translates into a mechanical variability that produces an error of up to 2% in the response of the studied devices when they are used to measure surface stress variations.

  1. Spatially Multiplexed Micro-Spectrophotometry in Bright Field Mode for Thin Film Characterization

    Science.gov (United States)

    Pini, Valerio; Kosaka, Priscila M.; Ruz, Jose J.; Malvar, Oscar; Encinar, Mario; Tamayo, Javier; Calleja, Montserrat

    2016-01-01

    Thickness characterization of thin films is of primary importance in a variety of nanotechnology applications, either in the semiconductor industry, quality control in nanofabrication processes or engineering of nanoelectromechanical systems (NEMS) because small thickness variability can strongly compromise the device performance. Here, we present an alternative optical method in bright field mode called Spatially Multiplexed Micro-Spectrophotometry that allows rapid and non-destructive characterization of thin films over areas of mm2 and with 1 μm of lateral resolution. We demonstrate an accuracy of 0.1% in the thickness characterization through measurements performed on four microcantilevers that expand an area of 1.8 mm2 in one minute of analysis time. The measured thickness variation in the range of few tens of nm translates into a mechanical variability that produces an error of up to 2% in the response of the studied devices when they are used to measure surface stress variations. PMID:27338398

  2. Spitzer 24 um Excesses for Bright Galactic Stars in Bootes and First Look Survey Fields

    CERN Document Server

    Hovhannisyan, L R; Weedman, D W; Le Floc'h, E; Houck, J R; Soifer, B T; Brand, K; Dey, A; Jannuzi, B T

    2009-01-01

    Optically bright Galactic stars (V 1 mJy are identified in Spitzer mid-infrared surveys within 8.2 square degrees for the Bootes field of the NOAO Deep Wide-Field Survey and within 5.5 square degrees for the First Look Survey (FLS). 128 stars are identified in Bootes and 140 in the FLS, and their photometry is given. (K-[24]) colors are determined using K magnitudes from the 2MASS survey for all stars in order to search for excess 24 um luminosity compared to that arising from the stellar photosphere. Of the combined sample of 268 stars, 141 are of spectral types F, G, or K, and 17 of these 141 stars have 24 um excesses with (K-[24]) > 0.2 mag. Using limits on absolute magnitude derived from proper motions, at least 8 of the FGK stars with excesses are main sequence stars, and estimates derived from the distribution of apparent magnitudes indicate that all 17 are main sequence stars. These estimates lead to the conclusion that between 9% and 17% of the main sequence FGK field stars in these samples have 24 u...

  3. Tracking mesenchymal stromal cells using an ultra-bright TAT-functionalized plasmonic-active nanoplatform.

    Science.gov (United States)

    Yuan, Hsiangkuo; Gomez, Jose A; Chien, Jennifer S; Zhang, Lunan; Wilson, Christy M; Li, Shuqin; Fales, Andrew M; Liu, Yang; Grant, Gerald A; Mirotsou, Maria; Dzau, Victor J; Vo-Dinh, Tuan

    2016-04-01

    High-resolution tracking of stem cells remains a challenging task. An ultra-bright contrast agent with extended intracellular retention is suitable for in vivo high-resolution tracking of stem cells following the implantation. Here, a plasmonic-active nanoplatform was developed for tracking mesenchymal stromal cells (MSCs) in mice. The nanoplatform consisted of TAT peptide-functionalized gold nanostars (TAT-GNS) that emit ultra-bright two-photon photoluminescence capable of tracking MSCs under high-resolution optical imaging. In vitro experiment showed TAT-GNS-labeled MSCs retained a similar differentiability to that of non-labeled MSCs controls. Due to their star shape, TAT-GNS exhibited greater intracellular retention than that of commercial Q-Tracker. In vivo imaging of TAT-GNS-labeled MSCs five days following intra-arterial injections in mice kidneys showed possible MSCs implantation in juxta-glomerular (JG) regions, but non-specifically in glomeruli and afferent arterioles as well. With future design to optimize GNS labeling specificity and clearance, plasmonic-active nanoplatforms may be a useful intracellular tracking tool for stem cell research. An ultra-bright intracellular contrast agent is developed using TAT peptide-functionalized gold nanostars (TAT-GNS). It poses minimal influence on the stem cell differentiability. It exhibits stronger two-photon photoluminescence and superior labeling efficiency than commercial Q-Tracker. Following renal implantation, some TAT-GNS-labeled MSCs permeate blood vessels and migrate to the juxta-glomerular region. PMID:27095616

  4. Investigating the fluid dynamics of rapid processes within microfluidic devices using bright-field microscopy.

    Science.gov (United States)

    Pirbodaghi, Tohid; Vigolo, Daniele; Akbari, Samin; deMello, Andrew

    2015-05-01

    The widespread application of microfluidic devices in the biological and chemical sciences requires the implementation of complex designs and geometries, which in turn leads to atypical fluid dynamic phenomena. Accordingly, a complete understanding of fluid dynamics in such systems is key in the facile engineering of novel and efficient analytical tools. Herein, we present an accurate approach for studying the fluid dynamics of rapid processes within microfluidic devices using bright-field microscopy with white light illumination and a standard high-speed camera. Specifically, we combine Ghost Particle Velocimetry and the detection of moving objects in automated video surveillance to track submicron size tracing particles via cross correlation between the speckle patterns of successive images. The efficacy of the presented technique is demonstrated by measuring the flow field over a square pillar (80 μm × 80 μm) in a 200 μm wide microchannel at high volumetric flow rates. Experimental results are in excellent agreement with those obtained via computational fluid dynamics simulations. The method is subsequently used to study the dynamics of droplet generation at a flow focusing microfluidic geometry. A unique feature of the presented technique is the ability to perform velocimetry analysis of high-speed phenomena, which is not possible using micron-resolution particle image velocimetry (μPIV) approaches based on confocal or fluorescence microscopy. PMID:25812165

  5. A new approach for 3D reconstruction from bright field TEM imaging: Beam precession assisted electron tomography

    International Nuclear Information System (INIS)

    The successful combination of electron beam precession and bright field electron tomography for 3D reconstruction is reported. Beam precession is demonstrated to be a powerful technique to reduce the contrast artifacts due to diffraction and curvature in thin foils. Taking advantage of these benefits, Precession assisted electron tomography has been applied to reconstruct the morphology of Sn precipitates embedded in an Al matrix, from a tilt series acquired in a range from +49o to -61o at intervals of 2o and with a precession angle of 0.6o in bright field mode. The combination of electron tomography and beam precession in conventional TEM mode is proposed as an alternative procedure to obtain 3D reconstructions of nano-objects without a scanning system or a high angle annular dark field detector. -- Highlights: → Electron beam precession reduces spurious diffraction contrast in bright field mode. → Bend contour related contrast depends on precession angle. → Electron beam precession is combined with bright field electron tomography. → Precession assisted BF tomography allowed 3D reconstruction of a Sn precipitate.

  6. Portable, battery-operated, low-cost, bright field and fluorescence microscope.

    Science.gov (United States)

    Miller, Andrew R; Davis, Gregory L; Oden, Z Maria; Razavi, Mohamad Reza; Fateh, Abolfazl; Ghazanfari, Morteza; Abdolrahimi, Farid; Poorazar, Shahin; Sakhaie, Fatemeh; Olsen, Randall J; Bahrmand, Ahmad Reza; Pierce, Mark C; Graviss, Edward A; Richards-Kortum, Rebecca

    2010-01-01

    This study describes the design and evaluation of a portable bright-field and fluorescence microscope that can be manufactured for $240 USD. The microscope uses a battery-operated LED-based flashlight as the light source and achieves a resolution of 0.8 microm at 1000x magnification in fluorescence mode. We tested the diagnostic capability of this new instrument to identify infections caused by the human pathogen, Mycobacterium tuberculosis. Sixty-four direct, decontaminated, and serially diluted smears were prepared from sputa obtained from 19 patients suspected to have M. tuberculosis infection. Slides were stained with auramine orange and evaluated as being positive or negative for M. tuberculosis with both the new portable fluorescence microscope and a laboratory grade fluorescence microscope. Concordant results were obtained in 98.4% of cases. This highly portable, low cost, fluorescence microscope may be a useful diagnostic tool to expand the availability of M. tuberculosis testing at the point-of-care in low resource settings. PMID:20694194

  7. Portable, battery-operated, low-cost, bright field and fluorescence microscope.

    Directory of Open Access Journals (Sweden)

    Andrew R Miller

    Full Text Available This study describes the design and evaluation of a portable bright-field and fluorescence microscope that can be manufactured for $240 USD. The microscope uses a battery-operated LED-based flashlight as the light source and achieves a resolution of 0.8 microm at 1000x magnification in fluorescence mode. We tested the diagnostic capability of this new instrument to identify infections caused by the human pathogen, Mycobacterium tuberculosis. Sixty-four direct, decontaminated, and serially diluted smears were prepared from sputa obtained from 19 patients suspected to have M. tuberculosis infection. Slides were stained with auramine orange and evaluated as being positive or negative for M. tuberculosis with both the new portable fluorescence microscope and a laboratory grade fluorescence microscope. Concordant results were obtained in 98.4% of cases. This highly portable, low cost, fluorescence microscope may be a useful diagnostic tool to expand the availability of M. tuberculosis testing at the point-of-care in low resource settings.

  8. Characteristics of a high brightness gaseous field ion source employing tungsten-carbon doped NiAl needles

    Energy Technology Data Exchange (ETDEWEB)

    Mousa, Marwan S., E-mail: mmousa@mutah.edu.jo [Department of Physics, Mu' tah University, P.O. Box 7, Al-Karak (Jordan)

    2011-05-15

    We report on the characterization of a high brightness gaseous field ion source using an emitter made of a NiAl needle containing tiny spherical tungsten-carbon precipitates. By field evaporation of such a multiphase alloy, a surface protrusion is formed out of a precipitate, which can act as a small source size field ion emitter. The emission current-voltage characteristics of this emitter were recorded for a variety of parameters. The results obtained suggest that its application as a stable ion source is possible even on long term operation. -- Research highlights: {yields} High brightness gaseous field ion source of precipitation hardened NiAl+W+C emitter. {yields} Emission current-voltage characteristics are recorded for a variety of parameters. {yields} Very small virtual source sizes and energy spreads can be attained. {yields} Results suggest that application as long term stable ion source is possible.

  9. Targeted imaging of EGFR overexpressed cancer cells by brightly fluorescent nanoparticles conjugated with cetuximab.

    Science.gov (United States)

    Gao, Meng; Su, Huifang; Lin, Gengwei; Li, Shiwu; Yu, Xingsu; Qin, Anjun; Zhao, Zujin; Zhang, Zhenfeng; Tang, Ben Zhong

    2016-08-11

    To improve the treatment efficiency and reduce side effects in cancer therapy, accurate diagnosis of cancer cell types at a molecular level is highly desirable. Fluorescent nanoparticles (NPs) are especially suitable for detecting molecular biomarkers of cancer with advantages of superior brightness, easy decoration and high resolution. However, the conventional organic fluorophores, conjugated polymers, and inorganic quantum dots suffer from the drawbacks of aggregation-caused quenching (ACQ), low photostability, and heavy metal toxicity, respectively, which severely restrict their applications in NPs-based fluorescence imaging. To overcome these limitations, herein, we have developed fluorescent nanoparticles based on a t-BuPITBT-TPE fluorophore derived from aggregation-induced emission (AIE)-active tetraphenylethene. Through encapsulating t-BuPITBT-TPE within biocompatible DSPE-PEG and further decorating with a monoclonal antibody cetuximab (C225), the obtained t-BuPITBT-TPE-C225 NPs can be used for targeted imaging of non-small cell lung cancer cells with an overexpressed epidermal growth factor receptor (EGFR). The specific targeting ability of t-BuPITBT-TPE-C225 NPs has been well verified by confocal microscopy and flow cytometry experiments. The t-BuPITBT-TPE-C225 NPs have shown significant advantages in terms of highly efficient red emission, good bio-compatibility, and excellent photostability. This work provides a promising method for precise diagnosis of cancer cells by antibody-functionalized fluorescent NPs with high brightness. PMID:27468980

  10. Characteristics of a high brightness gaseous field ion source employing tungsten-carbon doped NiAl needles.

    Science.gov (United States)

    Mousa, Marwan S

    2011-05-01

    We report on the characterization of a high brightness gaseous field ion source using an emitter made of a NiAl needle containing tiny spherical tungsten-carbon precipitates. By field evaporation of such a multiphase alloy, a surface protrusion is formed out of a precipitate, which can act as a small source size field ion emitter. The emission current-voltage characteristics of this emitter were recorded for a variety of parameters. The results obtained suggest that its application as a stable ion source is possible even on long term operation. PMID:21296502

  11. Human natural killer cell maturation defect supports in vivo CD56(bright to CD56(dim lineage development.

    Directory of Open Access Journals (Sweden)

    Carolina Inés Domaica

    Full Text Available Two populations of human natural killer (NK cells can be identified in peripheral blood. The majority are CD3(-CD56(dim cells while the minority exhibits a CD3(-CD56(bright phenotype. In vitro evidence indicates that CD56(bright cells are precursors of CD56(dim cells, but in vivo evidence is lacking. Here, we studied NK cells from a patient that suffered from a melanoma and opportunistic fungal infection during childhood. The patient exhibited a stable phenotype characterized by a reduction in the frequency of peripheral blood CD3(-CD56(dim NK cells, accompanied by an overt increase in the frequency and absolute number of CD3(-CD56(bright cells. These NK cells exhibited similar expression of perforin, CD57 and CD158, the major activating receptors CD16, NKp46, NKG2D, DNAM-1, and 2B4, as well as the inhibitory receptor CD94/NKG2A, on both CD56(bright and CD56(dim NK cells as healthy controls. Also, both NK cell subpopulations produced IFN-γ upon stimulation with cytokines, and CD3(-CD56(dim NK cells degranulated in response to cytokines or K562 cells. However, upon stimulation with cytokines, a substantial fraction of CD56(dim cells failed to up-regulate CD57 and CD158, showed a reduction in the percentage of CD16(+ cells, and CD56(bright cells did not down-regulate CD62L, suggesting that CD56(dim cells could not acquire a terminally differentiated phenotype and that CD56(bright cells exhibit a maturation defect that might result in a potential altered migration pattern. These observations, support the notion that NK cells of this patient display a maturation/activation defect that precludes the generation of mature NK cells at a normal rate accompanied by CD56(dim NK cells that cannot completely acquire a terminally differentiated phenotype. Thus, our results provide evidence that support the concept that in vivo CD56(bright NK cells differentiate into CD56(dim NK cells, and contribute to further understand human NK cell ontogeny.

  12. Human Natural Killer Cell Maturation Defect Supports In Vivo CD56bright to CD56dim Lineage Development

    Science.gov (United States)

    Domaica, Carolina Inés; Fuertes, Mercedes Beatriz; Uriarte, Ignacio; Girart, María Victoria; Sardañons, Jessica; Comas, Dorina Ileana; Di Giovanni, Daniela; Gaillard, María Isabel; Bezrodnik, Liliana; Zwirner, Norberto Walter

    2012-01-01

    Two populations of human natural killer (NK) cells can be identified in peripheral blood. The majority are CD3−CD56dim cells while the minority exhibits a CD3−CD56bright phenotype. In vitro evidence indicates that CD56bright cells are precursors of CD56dim cells, but in vivo evidence is lacking. Here, we studied NK cells from a patient that suffered from a melanoma and opportunistic fungal infection during childhood. The patient exhibited a stable phenotype characterized by a reduction in the frequency of peripheral blood CD3−CD56dim NK cells, accompanied by an overt increase in the frequency and absolute number of CD3−CD56bright cells. These NK cells exhibited similar expression of perforin, CD57 and CD158, the major activating receptors CD16, NKp46, NKG2D, DNAM-1, and 2B4, as well as the inhibitory receptor CD94/NKG2A, on both CD56bright and CD56dim NK cells as healthy controls. Also, both NK cell subpopulations produced IFN-γ upon stimulation with cytokines, and CD3−CD56dim NK cells degranulated in response to cytokines or K562 cells. However, upon stimulation with cytokines, a substantial fraction of CD56dim cells failed to up-regulate CD57 and CD158, showed a reduction in the percentage of CD16+ cells, and CD56bright cells did not down-regulate CD62L, suggesting that CD56dim cells could not acquire a terminally differentiated phenotype and that CD56bright cells exhibit a maturation defect that might result in a potential altered migration pattern. These observations, support the notion that NK cells of this patient display a maturation/activation defect that precludes the generation of mature NK cells at a normal rate accompanied by CD56dim NK cells that cannot completely acquire a terminally differentiated phenotype. Thus, our results provide evidence that support the concept that in vivo CD56bright NK cells differentiate into CD56dim NK cells, and contribute to further understand human NK cell ontogeny. PMID:23240056

  13. Mean-field model of interaction between bright vortex solitons in Bose-Einstein condensates

    International Nuclear Information System (INIS)

    Using the explicit numerical solution of the axially symmetric Gross-Pitaevskii equation we study the dynamics of interaction among vortex solitons in a rotating matter-wave bright soliton train in a radially trapped and axially free Bose-Einstein condensate to understand certain features of the experiment by Strecker et al (2002 Nature 417 150). In a soliton train, solitons of opposite phase (phase δ = π) repel and stay apart without changing shape; solitons with π = 0 attract, interact and coalesce, but eventually come out; solitons with a general δ usually repel but interact inelastically by exchanging matter. We study this and suggest future experiments with vortex solitons

  14. Evaluating the summer night sky brightness at a research field site on Lake Stechlin in northeastern Germany

    Science.gov (United States)

    Jechow, Andreas; Hölker, Franz; Kolláth, Zoltán; Gessner, Mark O.; Kyba, Christopher C. M.

    2016-09-01

    We report luminance measurements of the summer night sky at a field site on a freshwater lake in northeastern Germany (Lake Stechlin) to evaluate the amount of artificial skyglow from nearby and distant towns in the context of a planned study on light pollution. The site is located about 70 km north of Berlin in a rural area possibly belonging to one of the darkest regions in Germany. Continuous monitoring of the zenith sky luminance between June and September 2015 was conducted utilizing a Sky Quality Meter. With this device, typical values for clear nights in the range of 21.5-21.7 magSQM/arcsec2 were measured, which is on the order of the natural sky brightness during starry nights. On overcast nights, values down to 22.84 magSQM/arcsec2 were obtained, which is about one third as bright as on clear nights. The luminance measured on clear nights as well as the darkening with the presence of clouds indicates that there is very little influence of artificial skyglow on the zenith sky brightness at this location. Furthermore, fish-eye lens sky imaging luminance photometry was performed with a digital single-lens reflex camera on a clear night in the absence of moonlight. The photographs unravel several distant towns as possible sources of light pollution on the horizon. However, the low level of artificial skyglow makes the field site at Lake Stechlin an excellent location to study the effects of skyglow on a lake ecosystem in a controlled fashion.

  15. High brightness three-dimensional light field display based on the aspheric substrate Fresnel-lens-array with eccentric pupils

    Science.gov (United States)

    Gao, Xin; Sang, Xinzhu; Yu, Xunbo; Cao, Xuemei; Chen, Zhidong; Yan, Binbin; Yuan, Jinhui; Wang, Kuiru; Yu, Chongxiu; Dou, Wenhua; Xiao, Liquan

    2016-02-01

    The brightness and viewing field of the reproductive three-dimensional (3D) image are crucial factors to realize a comfortable 3D perception for the light field display based on the liquid crystal device (LCD). To improve the illuminance of 3D image with sub-image-units with small aperture angles and enlarge the viewing field, the illuminance of the Fresnel-lens combining with the sub-images on LCD is analyzed and designed. Theoretical and experimental results show that the Fresnel-lens-array with eccentric pupil(FAEP) can address above problems. A 3D light field display based on LCD with FAEP and directional diffuser screen are used to reconstruct the target 3D field. 25 parallax sub-images are projected to the directional diffuser screen to verify the improvement of illuminance and viewing field. To reduce eccentric aberration introduced by eccentric pupil, a novel structure of Fresnel-lens-array is presented to reduce the aberration. The illuminance and viewing field are well promoted at the same time. 3D image with the high quality can be achieved.

  16. KIC 4768731: a bright long-period roAp star in the Kepler Field

    CERN Document Server

    Smalley, B; Murphy, S J; Lehmann, H; Kurtz, D W; Holdsworth, D L; Cunha, M S; Balona, L A; Briquet, M; Bruntt, H; de Cat, P; Lampens, P; Thygesen, A O; Uytterhoeven, K

    2015-01-01

    We report the identification of 61.45 d^-1 (711.2 mu Hz) oscillations, with amplitudes of 62.6-mu mag, in KIC 4768731 (HD 225914) using Kepler photometry. This relatively bright (V=9.17) chemically peculiar star with spectral type A5 Vp SrCr(Eu) has previously been found to exhibit rotational modulation with a period of 5.21 d. Fourier analysis reveals a simple dipole pulsator with an amplitude that has remained stable over a 4-yr time span, but with a frequency that is variable. Analysis of high-resolution spectra yields stellar parameters of T_eff = 8100 +/- 200 K, log g = 4.0 +/- 0.2, [Fe/H] = +0.31 +/- 0.24 and v sin i = 14.8 +/- 1.6 km/s. Line profile variations caused by rotation are also evident. Lines of Sr, Cr, Eu, Mg and Si are strongest when the star is brightest, while Y and Ba vary in anti-phase with the other elements. The abundances of rare earth elements are only modestly enhanced compared to other roAp stars of similar T_eff and log g. Radial velocities in the literature suggest a significant...

  17. HIDES spectroscopy of bright detached eclipsing binaries from the Kepler field - I. Single-lined objects

    Science.gov (United States)

    Hełminiak, K. G.; Ukita, N.; Kambe, E.; Kozłowski, S. K.; Sybilski, P.; Ratajczak, M.; Maehara, H.; Konacki, M.

    2016-09-01

    We present results of our spectroscopic observations of nine detached eclipsing binaries (DEBs), selected from the Kepler Eclipsing Binary Catalog, that only show one set of spectral lines. Radial velocities (RVs) were calculated from the high-resolution spectra obtained with the HIgh-Dispersion Echelle Spectrograph (HIDES) instrument, attached to the 1.88-m telescope at the Okayama Astrophysical Observatory, and from the public Apache Point Observatory Galactic Evolution Experiment archive. In our sample, we found five single-lined binaries, with one component dominating the spectrum. The orbital and light-curve solutions were found for four of them, and compared with isochrones, in order to estimate absolute physical parameters and evolutionary status of the components. For the fifth case, we only update the orbital parameters, and estimate the properties of the unseen star. Two other systems show orbital motion with a period known from the eclipse timing variations (ETVs). For these we obtained parameters of outer orbits, by translating the ETVs to RVs of the centre of mass of the eclipsing binary, and combining with the RVs of the outer star. Of the two remaining ones, one is most likely a blend of a faint background DEB with a bright foreground star, which lines we see in the spectra, and the last case is possibly a quadruple bearing a sub-stellar mass object. Where possible, we compare our results with literature, especially with results from asteroseismology. We also report possible detections of solar-like oscillations in our RVs.

  18. Evaluating the summer night sky brightness at a research field site on Lake Stechlin in northeastern Germany

    CERN Document Server

    Jechow, Andreas; Kolláth, Zoltán; Gessner, Mark O; Kyba, Christopher C M

    2016-01-01

    We report on luminance measurements of the summer night sky at a field site on a freshwater lake in northeastern Germany (Lake Stechlin) to evaluate the amount of artificial skyglow from nearby and distant towns in the context of a planned study on light pollution. The site is located about 70 km north of Berlin in a rural area possibly belonging to one of the darkest regions in Germany. Continuous monitoring of the zenith sky luminance between June and September 2015 was conducted utilizing a Sky Quality Meter. With this device, typical values for clear nights in the range of 21.5-21.7 mag$_{SQM}/$arcsec$^2$ were measured, which is on the order of the natural sky brightness during starry nights. On overcast nights, values down to 22.84 mag$_{SQM}/$arcsec$^2$ were obtained, which is about one third as bright as on clear nights. The luminance measured on clear nights as well as the darkening with the presence of clouds indicate that there is very little influence of artificial skyglow on the zenith sky brightn...

  19. Natural killer cell cytokine response to M. bovis BCG Is associated with inhibited proliferation, increased apoptosis and ultimate depletion of NKp44(+CD56(bright cells.

    Directory of Open Access Journals (Sweden)

    Damien Portevin

    Full Text Available Mycobacterium bovis BCG, a live attenuated strain of M. bovis initially developed as a vaccine against tuberculosis, is also used as an adjuvant for immunotherapy of cancers and for treatment of parasitic infections. The underlying mechanisms are thought to rely on its immunomodulatory properties including the recruitment of natural killer (NK cells. In that context, we aimed to study the impact of M. bovis BCG on NK cell functions. We looked at cytotoxicity, cytokine production, proliferation and cell survival of purified human NK cells following exposure to single live particles of mycobacteria. We found that M. bovis BCG mediates apoptosis of NK cells only in the context of IL-2 stimulation during which CD56(bright NK cells are releasing IFN-γ in response to mycobacteria. We found that the presence of mycobacteria prevented the IL-2 induced proliferation and surface expression of NKp44 receptor by the CD56(bright population. In summary, we observed that M. bovis BCG is modulating the functions of CD56(bright NK cells to drive this subset to produce IFN-γ before subsequent programmed cell death. Therefore, IFN-γ production by CD56(bright cells constitutes the main effector mechanism of NK cells that would contribute to the benefits observed for M. bovis BCG as an immunotherapeutic agent.

  20. Biofeedback systems for stress reduction : Towards a bright future for a revitalized field

    NARCIS (Netherlands)

    Broek, E.L. van den; Westerink, J.H.D.M.

    2012-01-01

    Stress has recently been baptized as the black death of the 21st century, which illustrates its threat to current health standards. This article proposes biofeedback systems as a means to reduce stress. A concise state-of-the-art introduction on biofeedback systems is given. The field of mental heal

  1. Biofeedback systems for stress reduction: Towards a Bright Future for a Revitalized Field

    NARCIS (Netherlands)

    Broek, van den Egon L.; Westerink, Joyce H.D.M.; Conchon, E.; Correia, C.; Fred, A.; Gamboa, H.

    2012-01-01

    Stress has recently been baptized as the black death of the 21st century, which illustrates its threat to current health standards. This article proposes biofeedback systems as a means to reduce stress. A concise state-ofthe-art introduction on biofeedback systems is given. The field of mental healt

  2. Evaluation of CD56dim and CD56bright natural killer cells in peripheral blood of women with IVF failures

    Directory of Open Access Journals (Sweden)

    Farahnaz Mardanian

    2015-09-01

    Full Text Available Background: Infertility is an increasing medical and social problem. In vitro fertilization (IVF has become a common and accessible treatment for a wide variety of indications that have variable outcomes. Natural killer (NK cells have been identified as relevant immunological factors involved in reproductive success or failure. Objective: The aim of this study was to compare the percentage of peripheral blood CD56+ (CD56dim and CD56bright cells and the level of NK cell in patients with IVF failure with those of successful IVF control women. Materials and Methods: We assessed the level of CD56dim CD16+ and CD56bright CD16- cells in 50 women under IVF treatment and compared between successful IVF and IVF failure with the flowcytometry technique. Results: Of studied women, 68% did not response to IVF therapy and 32% had successful IVF, the level of CD56dim CD16+ cells in women with IVF failure was significantly higher than successful IVF (p<0.0001 but the level of CD56bright CD16- cells was not significantly different between women with IVF failure and successful IVF (p=0.28. Conclusion: The results of present study demonstrated that the level of NK cells as a risk factor is associated with pregnancy loss in women with IVF failure. However, number of sample in this study is low and further studies with more sample size are needed to be done. We suggest considering treatment option for women undergoing repeated IVF failure with increased percentage of CD56dim cells and the level of peripheral blood NK cell.

  3. Development of Schistosoma mansoni worms in mice analyzed by bright field and confocal microscopy

    Directory of Open Access Journals (Sweden)

    Carla de Lamare Biolchini

    2006-10-01

    Full Text Available The blood flukes of mammals (Digenea: Schistosomatidae are among trematodes unique whose adult worms have separeted sexes which are dissimilar in appearance. The developmental features, growth and organogenesis of Schistosoma mansoni were studied in Swiss Webster mice by a digital system for image analysis and confocal microscopy. Data so far obtained showed two phases with significative morphological changes at 3-4 weeks post-infection, and a gradual similar development onwards in the reproductive system and tegument. Our male-dependent phase demonstrated that mating occurs before sexual maturing. At week three, the majority of male worms (59% had formed the gynaecophoric canal although testicular lobes and tegumental tubercles were absent. By this time, 33% females had an incipient ovary (without cellular differentiation. At week four, 77.2% males presented testicular lobes with few germinative cells while 26% had developing tegumental tubercles. The immature ovary was observed in 69% females. Suckers followed different pattern of growth between male and females. The size of oral and ventral suckers from six-week-old male worms grew abruptly (3.0 fold more than that of three-week-old. In female worms, maximum growth was attained at week four, reducing in size thereafter. From sixth week onwards, all specimens showed the fully developed reproductive system. Probably, these features are morphological traits which schistosome has experienced from hermaphrodite to dioecy.

  4. Integral field spectroscopy of selected areas of the Bright bar and Orion-S cloud in the Orion nebula

    Science.gov (United States)

    Mesa-Delgado, A.; Núñez-Díaz, M.; Esteban, C.; López-Martín, L.; García-Rojas, J.

    2011-10-01

    We present integral field spectroscopy of two selected zones in the Orion nebula obtained with the Potsdam Multi-Aperture Spectrophotometer, covering the optical spectral range from 3500 to 7200 Å and with a spatial resolution of 1 arcsec. The observed zones are located on the prominent Bright bar and on the brightest area at the north-east of the Orion south cloud, both containing remarkable ionization fronts. We obtain maps of emission-line fluxes and ratios, electron density and temperatures, and chemical abundances. We study the ionization structure and morphology of both fields, whose ionization fronts show different inclination angles with respect to the plane of the sky. We find that the maps of electron density, O+/H+ and O/H ratios show a rather similar structure. We interpret this as produced by the strong dependence on density of the [O II] lines used to derive the O+ abundance, and that our nominal values of electron density - derived from the [S II] line ratio - may be slightly higher than the appropriate value for the O+ zone. We measure the faint recombination lines of O II in the field at the north-east of the Orion south cloud, allowing us to explore the so-called abundance discrepancy problem. We find a rather constant abundance discrepancy across the field and a mean value similar to that determined in other areas of the Orion nebula, indicating that the particular physical conditions of this ionization front do not contribute to this discrepancy. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  5. Regeneration-associated WNT Signaling Is Activated in Long-term Reconstituting AC133bright Acute Myeloid Leukemia Cells

    Directory of Open Access Journals (Sweden)

    Alessandro Beghini

    2012-12-01

    Full Text Available Acute myeloid leukemia (AML is a genetically heterogeneous clonal disorder characterized by two molecularly distinct self-renewing leukemic stem cell (LSC populations most closely related to normal progenitors and organized as a hierarchy. A requirement for WNT/β-catenin signaling in the pathogenesis of AML has recently been suggested by a mouse model. However, its relationship to a specific molecular function promoting retention of self-renewing leukemia-initiating cells (LICs in human remains elusive. To identify transcriptional programs involved in the maintenance of a self-renewing state in LICs, we performed the expression profiling in normal (n = 10 and leukemic (n = 33 human long-term reconstituting AC133+ cells, which represent an expanded cell population in most AML patients. This study reveals the ligand-dependent WNT pathway activation in AC133bright AML cells and shows a diffuse expression and release of WNT10B, a hematopoietic stem cell regenerative-associated molecule. The establishment of a primary AC133+ AML cell culture (A46 demonstrated that leukemia cells synthesize and secrete WNT ligands, increasing the levels of dephosphorylated β-catenin in vivo. We tested the LSC functional activity in AC133+ cells and found significant levels of engraftment upon transplantation of A46 cells into irradiated Rag2-/-γc-/- mice. Owing to the link between hematopoietic regeneration and developmental signaling, we transplanted A46 cells into developing zebrafish. This system revealed the formation of ectopic structures by activating dorsal organizer markers that act downstream of the WNT pathway. In conclusion, our findings suggest that AC133bright LSCs are promoted by misappropriating homeostatic WNT programs that control hematopoietic regeneration.

  6. Surface brightness profiles of blue compact dwarf galaxies in the GOODS-N and GOODS-S field

    CERN Document Server

    Lian, Jianhui; Jiang, Ning; Yan, Wei; Gao, Yulong

    2016-01-01

    We investigate the structural properties of the underlying hosts of 34 blue compact dwarf (BCD) galaxies with deep near-infrared (NIR) photometry. The BCD sample is selected from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey in the Great observatories origins Deep Survey North and South fields. We extract the surface brightness profile (SBP) in the optical F 435W and NIR F 160W bands. The SBPs of BCDs in the H band reach 26 mag arcsec^-2 at the 3\\sigma level, which is so far the deepest NIR imaging of BCDs. Then we fit the SBPs with one- and two- component Sersic models. About half of the BCDs favour the two-component model which significantly improves the fit quality. The effective radii of the underlying hosts of BCDs in the B band are smaller than those of early-type dwarfs (dEs) and dwarf irregulars at a fixed luminosity. This discrepancy is similar to findings in many previous works. However, the difference in structural parameters between BCDs and other dwarf galaxies seems to be less sig...

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

    International Nuclear Information System (INIS)

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

  8. Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies

    CERN Document Server

    Marsden, S C; Vélez, J C Ramírez; Alecian, E; Brown, C J; Carter, B D; Donati, J F; Dunstone, N; Hart, R; Semel, M; Waite, I A

    2011-01-01

    Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian Telescope using the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. Brightness and surface magnetic field topologies were reconstructed for the star using the technique of least-squares deconvolution to increase the signal-to-noise of the data. The reconstructed brightness maps show that HD 141943 had a weak polar spot and a significant amount of low latitude features, with little change in the latitude distribution of the spots over the 4 years of observations. The surface magnetic field was reconstructed at three of the epochs from a high order (l <= 30) spherical harmonic expansion of the spectropolarimetric observations. The reconstructed magnetic topologies show that in 2007 and 2010 the surface magnetic field was reasonably balanced betwee...

  9. Cell separation using electric fields

    Science.gov (United States)

    Mangano, Joseph (Inventor); Eppich, Henry (Inventor)

    2009-01-01

    The present invention involves methods and devices which enable discrete objects having a conducting inner core, surrounded by a dielectric membrane to be selectively inactivated by electric fields via irreversible breakdown of their dielectric membrane. One important application of the invention is in the selection, purification, and/or purging of desired or undesired biological cells from cell suspensions. According to the invention, electric fields can be utilized to selectively inactivate and render non-viable particular subpopulations of cells in a suspension, while not adversely affecting other desired subpopulations. According to the inventive methods, the cells can be selected on the basis of intrinsic or induced differences in a characteristic electroporation threshold, which can depend, for example, on a difference in cell size and/or critical dielectric membrane breakdown voltage. The invention enables effective cell separation without the need to employ undesirable exogenous agents, such as toxins or antibodies. The inventive method also enables relatively rapid cell separation involving a relatively low degree of trauma or modification to the selected, desired cells. The inventive method has a variety of potential applications in clinical medicine, research, etc., with two of the more important foreseeable applications being stem cell enrichment/isolation, and cancer cell purging.

  10. A Quantitative Method for Comparing the Brightness of Antibody-dye Reagents and Estimating Antibodies Bound per Cell.

    Science.gov (United States)

    Kantor, Aaron B; Moore, Wayne A; Meehan, Stephen; Parks, David R

    2016-01-01

    We present a quantitative method for comparing the brightness of antibody-dye reagents and estimating antibodies bound per cell. The method is based on complementary binding of test and fill reagents to antibody capture microspheres. Several aliquots of antibody capture beads are stained with varying amounts of the test conjugate. The remaining binding sites on the beads are then filled with a second conjugate containing a different fluorophore. Finally, the fluorescence of the test conjugate compared to the fill conjugate is used to measure the relative brightness of the test conjugate. The fundamental assumption of the test-fill method is that if it takes X molecules of one test antibody to lower the fill signal by Y units, it will take the same X molecules of any other test antibody to give the same effect. We apply a quadratic fit to evaluate the test-fill signal relationship across different amounts of test reagent. If the fit is close to linear, we consider the test reagent to be suitable for quantitative evaluation of antibody binding. To calibrate the antibodies bound per bead, a PE conjugate with 1 PE molecule per antibody is used as a test reagent and the fluorescence scale is calibrated with Quantibrite PE beads. When the fluorescence per antibody molecule has been determined for a particular conjugate, that conjugate can be used for measurement of antibodies bound per cell. This provides comparisons of the brightness of different conjugates when conducted on an instrument whose statistical photoelectron (Spe) scales are known. © 2016 by John Wiley & Sons, Inc.

  11. Bright/Arid3A Acts as a Barrier to Somatic Cell Reprogramming through Direct Regulation of Oct4, Sox2, and Nanog

    Directory of Open Access Journals (Sweden)

    Melissa Popowski

    2014-01-01

    Full Text Available We show here that singular loss of the Bright/Arid3A transcription factor leads to reprograming of mouse embryonic fibroblasts (MEFs and enhancement of standard four-factor (4F reprogramming. Bright-deficient MEFs bypass senescence and, under standard embryonic stem cell (ESC culture conditions, spontaneously form clones that in vitro express pluripotency markers, differentiate to all germ lineages, and in vivo form teratomas and chimeric mice. We demonstrate that BRIGHT binds directly to the promoter/enhancer regions of Oct4, Sox2, and Nanog to contribute to their repression in both MEFs and ESCs. Thus, elimination of the BRIGHT barrier may provide an approach for somatic cell reprogramming.

  12. Out of the darkness and into the light: bright field in situ hybridisation for delineation of ERBB2 (HER2) status in breast carcinoma

    OpenAIRE

    Gruver, Aaron M; Peerwani, Ziad; Tubbs, Raymond R.

    2010-01-01

    Assessment of ERBB2 (HER2) status in breast carcinomas has become critical in determining response to the humanised monoclonal antibody trastuzumab. The current joint College of American Pathologists and the American Society of Clinical Oncology guidelines for the evaluation of HER2 status in breast carcinoma involve testing by immunohistochemistry and fluorescence in situ hybridisation (FISH). However, neither of these modalities is without limitations. Novel bright field in situ hybridisati...

  13. Cytotoxicity of CD56bright NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A

    OpenAIRE

    Nielsen, Natasja; Ødum, Niels; Ursø, Birgitte; Lanier, Lewis L; Spee, Pieter

    2012-01-01

    In mouse models of chronic inflammatory diseases, Natural Killer (NK) cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically distinguished as CD16(+)CD56(dim) and CD16(dim/-)CD56(bright). An expansion in the CD56(bright) NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggest...

  14. Cytotoxicity of CD56bright NK Cells towards Autologous Activated CD4+ T Cells Is Mediated through NKG2D, LFA-1 and TRAIL and Dampened via CD94/NKG2A

    OpenAIRE

    Natasja Nielsen; Niels Ødum; Birgitte Ursø; Lanier, Lewis L; Pieter Spee

    2012-01-01

    In mouse models of chronic inflammatory diseases, Natural Killer (NK) cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically distinguished as CD16(+)CD56(dim) and CD16(dim/-)CD56(bright). An expansion in the CD56(bright) NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggest...

  15. Monte Carlo electron-trajectory simulations in bright-field and dark-field STEM: Implications for tomography of thick biological sections

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, A.A.; Hohmann-Marriott, M.F.; Zhang, G. [Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bldg. 13, Rm. 3N17, 13 South Drive, Bethesda, MD 20892-5766 (United States); Leapman, R.D. [Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bldg. 13, Rm. 3N17, 13 South Drive, Bethesda, MD 20892-5766 (United States)], E-mail: leapmanr@mail.nih.gov

    2009-02-15

    A Monte Carlo electron-trajectory calculation has been implemented to assess the optimal detector configuration for scanning transmission electron microscopy (STEM) tomography of thick biological sections. By modeling specimens containing 2 and 3 at% osmium in a carbon matrix, it was found that for 1-{mu}m-thick samples the bright-field (BF) and annular dark-field (ADF) signals give similar contrast and signal-to-noise ratio provided the ADF inner angle and BF outer angle are chosen optimally. Spatial resolution in STEM imaging of thick sections is compromised by multiple elastic scattering which results in a spread of scattering angles and thus a spread in lateral distances of the electrons leaving the bottom surface. However, the simulations reveal that a large fraction of these multiply scattered electrons are excluded from the BF detector, which results in higher spatial resolution in BF than in high-angle ADF images for objects situated towards the bottom of the sample. The calculations imply that STEM electron tomography of thick sections should be performed using a BF rather than an ADF detector. This advantage was verified by recording simultaneous BF and high-angle ADF STEM tomographic tilt series from a stained 600-nm-thick section of C. elegans. It was found that loss of spatial resolution occurred markedly at the bottom surface of the specimen in the ADF STEM but significantly less in the BF STEM tomographic reconstruction. Our results indicate that it might be feasible to use BF STEM tomography to determine the 3D structure of whole eukaryotic microorganisms prepared by freeze-substitution, embedding, and sectioning.

  16. 3D photospheric velocity field of a Supergranular cell

    CERN Document Server

    Del Moro, Dario; Berrilli, Francesco

    2007-01-01

    We investigate the plasma flow properties inside a Supergranular (SG) cell, in particular its interaction with small scale magnetic field structures. The SG cell has been identified using the magnetic network (CaII wing brightness) as proxy, applying the TST to high spatial, spectral and temporal resolution observations obtained by IBIS. The full 3D velocity vector field for the SG has been reconstructed at two different photospheric heights. In order to strengthen our findings, we also computed the mean radial flow of the SG by means of cork tracing. We also studied the behaviour of the horizontal and Line of Sight plasma flow cospatial with cluster of bright CaII structures of magnetic origin to better understand the interaction between photospheric convection and small scale magnetic features. The SG cell we investigated seems to be organized with an almost radial flow from its centre to the border. The large scale divergence structure is probably created by a compact region of costant up-flow close to the...

  17. Plasmon-induced transparency in metamaterials: Active near field coupling between bright superconducting and dark metallic mode resonators

    Science.gov (United States)

    Cao, Wei; Singh, Ranjan; Zhang, Caihong; Han, Jiaguang; Tonouchi, Masayoshi; Zhang, Weili

    2013-09-01

    Structured plasmonic metamaterial devices offer the design flexibility to be size scaled for operation across the electromagnetic spectrum and are extremely attractive for generating electromagnetically induced transparency and slow-light behaviors via coupling of bright and dark subwavelength resonators. Here, we experimentally demonstrate a thermally active superconductor-metal coupled resonator based hybrid terahertz metamaterial on a sapphire substrate that shows tunable transparency and slow light behavior as the metamaterial chip is cooled below the high-temperature superconducting phase transition temperature. This hybrid metamaterial opens up the avenues for designing micro-sized active circuitry with switching, modulation, and "slowing down terahertz light" capabilities.

  18. Expansion of circulating CD56bright natural killer cells in patients with JAK2-positive chronic myeloproliferative neoplasms during treatment with interferon-α

    DEFF Research Database (Denmark)

    Riley, Caroline H; Hansen, Morten; Brimnes, Marie K;

    2015-01-01

    -tumor immune response against the JAK2-mutated clone. The objective of this study was to investigate circulating levels and phenotype of natural killer cells in 29 JAK2-positive MPN patients during IFN-α treatment. Furthermore, functional studies of NK cells upon target-cell recognition and cytokine......In recent years, major molecular remissions have been observed in patients with JAK2-positive chronic myeloproliferative neoplasms (MPNs) after therapy with IFN-α. IFN-α is known to have altering effects on immune cells involved in immune surveillance and might consequently enhance anti...... stimulation were performed. The CD56(bright) and CD56(dim) NK cell subtypes display different properties in terms of cytokine production and cytotoxicity, respectively. Our results show a significant increase in the proportion of CD56(bright) NK cells and a decreasing CD56(dim) population during treatment...

  19. Cytotoxic functions and susceptibility to apoptosis of human CD56(bright) NK cells differentiated in vitro from CD34⁺ hematopoietic progenitors.

    Science.gov (United States)

    Zamai, Loris; Del Zotto, Genny; Buccella, Flavia; Galeotti, Laura; Canonico, Barbara; Luchetti, Francesca; Papa, Stefano

    2012-04-01

    Cytotoxic functions and susceptibility to apoptosis are crucial aspects of NK cells suitable to counter cancer after infusion in oncologic patients. To test the feasibility and the usefulness of infusing in vitro generated NK cells, these two features were investigated in NK cells developed in vitro from CD34⁺ hematopoietic progenitors. Purified CD34⁺ cells were cultured for 15-30 days with FLT-3 ligand (FLT3-L) and IL-15 with or without IL-21. To induce terminal differentiation, NK cells were cultured for further 15 days with IL-15, IL-21, or their combination. A CD56(dim) /CD16⁺ NK subset, expressing high level of perforin, granzymes, and LFA-1, appeared early in cultures with FLT3-L, IL-15, and IL-21, but it quickly died, indicating its predisposition to apoptosis. On the contrary, CD56(bright) NK cells generated after 30 days of culture with FLT3-L plus IL-15 did not show a considerable apoptosis, nevertheless only a subset of these cells expressed granzyme-B, perforin, LFA-1, and CD94-CD159a heterodimer, indicating a functional immaturity. Interestingly, further 15 days of culture with IL-21 plus IL-15 did not induce the generation of CD56(dim) cells from the CD56(bright) subset and actually inhibited IL-15-induced maturation/activation of this latter subset. In fact, IL-15 alone upregulated granzyme-B, TRAIL, Fas ligand, CD94-CD159a, LFA-1, CD16, KIRs, and TRAIL-R2 on CD56(bright) NK cells. Our results suggest that during differentiation CD56(bright) NK cells, similarly to mature activated NK cells, become highly cytotoxic and are relatively resistant to apoptosis induced by TNF family members. PMID:22319021

  20. Cross-talk between the cytosolic mevalonate and the plastidial methylerythritol phosphate pathways in tobacco bright yellow-2 cells.

    Science.gov (United States)

    Hemmerlin, Andréa; Hoeffler, Jean-François; Meyer, Odile; Tritsch, Denis; Kagan, Isabelle A; Grosdemange-Billiard, Catherine; Rohmer, Michel; Bach, Thomas J

    2003-07-18

    In plants, two pathways are utilized for the synthesis of isopentenyl diphosphate, the universal precursor for isoprenoid biosynthesis. The key enzyme of the cytoplasmic mevalonic acid (MVA) pathway is 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). Treatment of Tobacco Bright Yellow-2 (TBY-2) cells by the HMGR-specific inhibitor mevinolin led to growth reduction and induction of apparent HMGR activity, in parallel to an increase in protein representing two HMGR isozymes. Maximum induction was observed at 24 h. 1-Deoxy-d-xylulose (DX), the dephosphorylated first precursor of the plastidial 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway, complemented growth inhibition by mevinolin in the low millimolar concentration range. Furthermore, DX partially re-established feedback repression of mevinolin-induced HMGR activity. Incorporation studies with [1,1,1,4-2H4]DX showed that sterols, normally derived from MVA, in the presence of mevinolin are synthesized via the MEP pathway. Fosmidomycin, an inhibitor of 1-deoxy-d-xylulose-5-phosphate reductoisomerase, the second enzyme of the MEP pathway, was utilized to study the reverse complementation. Growth inhibition by fosmidomycin of TBY-2 cells could be partially overcome by MVA. Chemical complementation was further substantiated by incorporation of [2-13C]MVA into plastoquinone, representative of plastidial isoprenoids. Best rates of incorporation of exogenous stably labeled precursors were observed in the presence of both inhibitors, thereby avoiding internal isotope dilution.

  1. Cytotoxicity of CD56bright NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A

    DEFF Research Database (Denmark)

    Nielsen, Natasja; Ødum, Niels; Ursø, Birgitte;

    2012-01-01

    In mouse models of chronic inflammatory diseases, Natural Killer (NK) cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically...... distinguished as CD16(+)CD56(dim) and CD16(dim/-)CD56(bright). An expansion in the CD56(bright) NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggesting an immunoregulatory role for this subset in vivo. Here we compared the regulation of activated human CD......4(+) T cells by CD56(dim) and CD56(bright) autologous NK cells in vitro. Both subsets efficiently killed activated, but not resting, CD4(+) T cells. The activating receptor NKG2D, as well as the integrin LFA-1 and the TRAIL pathway, played important roles in this process. Degranulation by NK cells...

  2. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines. (LEW)

  3. An unexpected drop in the magnetic field of the X-ray pulsar V0332+53 after the bright outburst occurred in 2015

    CERN Document Server

    Cusumano, G; D'Ai, A; Segreto, A; Tagliaferri, G; Barthelmy, S D; Gehrels, N

    2016-01-01

    How the accreted mass settling on the surface of a neutron star affects the topology of the magnetic field and how the secular evolution of the binary system depends on the magnetic field change is still an open issue. We report evidence for a clear drop in the observed magnetic field in the accreting pulsar V0332+53 after undergoing a bright 3-month long X-ray outburst. We determine the field from the position of the fundamental cyclotron line in its X-ray spectrum and relate it to the luminosity. For equal levels of luminosity, in the declining phase we measure a systematically lower value of the cyclotron line energy with respect to the rising phase. This results in a drop of ~1.7 x 10^11 G of the observed field between the onset and the end of the outburst. The settling of the accreted plasma onto the polar cap seems to induce a distortion of the magnetic field lines weakening their intensity along the accretion columns. Therefore the dissipation rate of the magnetic field could be much faster than previo...

  4. A Bright Submillimeter Source in the Bullet Cluster (1E0657--56) Field Detected with BLAST

    CERN Document Server

    Rex, Marie; Aretxaga, Itziar; Bock, James J; Chapin, Edward L; Devlin, Mark J; Dicker, Simon R; Griffin, Matthew; Gundersen, Joshua O; Halpern, Mark; Hargrave, Peter C; Hughes, David H; Klein, Jeff; Marsden, Gaelen; Martin, Peter G; Mauskopf, Philip; Netterfield, Calvin B; Olmi, Luca; Pascale, Enzo; Patanchon, Guillaume; Scott, Douglas; Semisch, Christopher; Thomas, Nicholas; Truch, Matthew D P; Tucker, Carole; Tucker, Gregory S; Viero, Marco P; Wiebe, Donald V

    2009-01-01

    We present the 250, 350, and 500 micron detection of bright submillimeter emission in the direction of the Bullet Cluster measured by the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST). The 500 micron centroid is coincident with an AzTEC 1.1 millimeter detection at a position close to the peak lensing magnification produced by the cluster. However, the 250 micron and 350 micron emission is resolved and elongated, with centroid positions shifted toward the south of the AzTEC source and a differential shift between bands that cannot be explained by pointing uncertainties. We therefore conclude that the BLAST detection is contaminated by emission from foreground galaxies associated with the Bullet Cluster. The submillimeter redshift estimate based on 250-1100 micron photometry at the position of the AzTEC source is z_phot = 2.9 (+0.6/-0.3), consistent with the infrared color redshift estimation of the most likely Spitzer IRAC counterpart. These flux densities indicate an apparent far-infrared lumin...

  5. Cytotoxicity of CD56(bright NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A.

    Directory of Open Access Journals (Sweden)

    Natasja Nielsen

    Full Text Available In mouse models of chronic inflammatory diseases, Natural Killer (NK cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically distinguished as CD16(+CD56(dim and CD16(dim/-CD56(bright. An expansion in the CD56(bright NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggesting an immunoregulatory role for this subset in vivo. Here we compared the regulation of activated human CD4(+ T cells by CD56(dim and CD56(bright autologous NK cells in vitro. Both subsets efficiently killed activated, but not resting, CD4(+ T cells. The activating receptor NKG2D, as well as the integrin LFA-1 and the TRAIL pathway, played important roles in this process. Degranulation by NK cells towards activated CD4(+ T cells was enhanced by IL-2, IL-15, IL-12+IL-18 and IFN-α. Interestingly, IL-7 and IL-21 stimulated degranulation by CD56(bright NK cells but not by CD56(dim NK cells. NK cell killing of activated CD4(+ T cells was suppressed by HLA-E on CD4(+ T cells, as blocking the interaction between HLA-E and the inhibitory CD94/NKG2A NK cell receptor enhanced NK cell degranulation. This study provides new insight into CD56(dim and CD56(bright NK cell-mediated elimination of activated autologous CD4(+ T cells, which potentially may provide an opportunity for therapeutic treatment of chronic inflammation.

  6. Cytotoxicity of CD56(bright) NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A.

    Science.gov (United States)

    Nielsen, Natasja; Ødum, Niels; Ursø, Birgitte; Lanier, Lewis L; Spee, Pieter

    2012-01-01

    In mouse models of chronic inflammatory diseases, Natural Killer (NK) cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically distinguished as CD16(+)CD56(dim) and CD16(dim/-)CD56(bright). An expansion in the CD56(bright) NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggesting an immunoregulatory role for this subset in vivo. Here we compared the regulation of activated human CD4(+) T cells by CD56(dim) and CD56(bright) autologous NK cells in vitro. Both subsets efficiently killed activated, but not resting, CD4(+) T cells. The activating receptor NKG2D, as well as the integrin LFA-1 and the TRAIL pathway, played important roles in this process. Degranulation by NK cells towards activated CD4(+) T cells was enhanced by IL-2, IL-15, IL-12+IL-18 and IFN-α. Interestingly, IL-7 and IL-21 stimulated degranulation by CD56(bright) NK cells but not by CD56(dim) NK cells. NK cell killing of activated CD4(+) T cells was suppressed by HLA-E on CD4(+) T cells, as blocking the interaction between HLA-E and the inhibitory CD94/NKG2A NK cell receptor enhanced NK cell degranulation. This study provides new insight into CD56(dim) and CD56(bright) NK cell-mediated elimination of activated autologous CD4(+) T cells, which potentially may provide an opportunity for therapeutic treatment of chronic inflammation. PMID:22384114

  7. The LBT Bootes Field Survey: I. The Rest-frame UV and Luminosity Functions and Clustering of Bright Lyman Break Galaxies at z~3

    CERN Document Server

    Bian, Fuyan; Jiang, Linhua; McGreer, Ian; Dey, Arjun; Green, Richard; Maiolino, Roberto; Walter, Fabian; Lee, Kyoung-Soo; Dave, Romeel

    2013-01-01

    We present a deep LBT/LBC U-band imaging survey (9 deg2) covering the NOAO Bootes field. A total of 14,485 Lyman Break Galaxies (LBGs) at z~3 are selected, which are used to measure the rest-frame UV luminosity function (LF). The large sample size and survey area reduce the LF uncertainties due to Poisson statistics and cosmic variance by >3 compared to previous studies. At the bright end, the LF shows excess power compared to the best-fit Schechter function, which can be attributed to the contribution of $z\\sim3$ quasars. We compute the rest-frame near-infrared LF and stellar mass function (SMF) of z~3 LBGs based on the R-band and IRAC [4.5 micro m]-band flux relation. We investigate the evolution of the UV LFs and SMFs between z~7 and z~3, which supports a rising star formation history in the LBGs. We study the spatial correlation function of two bright LBG samples and estimate their average host halo mass. We find a tight relation between the host halo mass and the galaxy star formation rate (SFR),which fo...

  8. Development of TEM and SEM high brightness electron guns using cold-field emission from a carbon nanotip

    International Nuclear Information System (INIS)

    A newly developed carbon cone nanotip (CCnT) has been used as field emission cathode both in low voltage SEM (30 kV) electron source and high voltage TEM (200 kV) electron source. The results clearly show, for both technologies, an unprecedented stability of the emission and the probe current with almost no decay during 1 h, as well as a very small noise (rms less than 0.5%) compared to standard sources which use tungsten tips as emitting cathode. In addition, quantitative electric field mapping around the FE tip have been performed using in situ electron holography experiments during the emission of the new tip. These results show the advantage of the very high aspect ratio of the new CCnT which induces a strong enhancement of the electric field at the apex of the tip, leading to very small extraction voltage (some hundred of volts) for which the field emission will start. The combination of these experiments with emission current measurements has also allowed to extract an exit work function value of 4.8 eV. - Highlights: • We develop a new field emission cathode based on carbon material. • We determine the exit work function of this new cathode using a combination of in situ electron holography and finite element modeling. • We show that the stability of cold-field emitted current can be improved with no decay during one hour of emission with a lower emission noise (less than 0.5%). • We used this cathode both for 200 kV TEM and 30 kV SEM cold field emission source. • As a TEM source, we also observe an increase of the spatial coherence using Fresnel fringes contrast

  9. Development of TEM and SEM high brightness electron guns using cold-field emission from a carbon nanotip

    Energy Technology Data Exchange (ETDEWEB)

    Houdellier, F.; Knoop, L. de; Gatel, C.; Masseboeuf, A. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France); Mamishin, S.; Taniguchi, Y. [Hitachi High-Technologies Corporation, 882, Ichige, Hitachinaka, Ibaraki 312-8504 (Japan); Delmas, M.; Monthioux, M.; Hÿtch, M.J.; Snoeck, E. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France)

    2015-04-15

    A newly developed carbon cone nanotip (CCnT) has been used as field emission cathode both in low voltage SEM (30 kV) electron source and high voltage TEM (200 kV) electron source. The results clearly show, for both technologies, an unprecedented stability of the emission and the probe current with almost no decay during 1 h, as well as a very small noise (rms less than 0.5%) compared to standard sources which use tungsten tips as emitting cathode. In addition, quantitative electric field mapping around the FE tip have been performed using in situ electron holography experiments during the emission of the new tip. These results show the advantage of the very high aspect ratio of the new CCnT which induces a strong enhancement of the electric field at the apex of the tip, leading to very small extraction voltage (some hundred of volts) for which the field emission will start. The combination of these experiments with emission current measurements has also allowed to extract an exit work function value of 4.8 eV. - Highlights: • We develop a new field emission cathode based on carbon material. • We determine the exit work function of this new cathode using a combination of in situ electron holography and finite element modeling. • We show that the stability of cold-field emitted current can be improved with no decay during one hour of emission with a lower emission noise (less than 0.5%). • We used this cathode both for 200 kV TEM and 30 kV SEM cold field emission source. • As a TEM source, we also observe an increase of the spatial coherence using Fresnel fringes contrast.

  10. Perturbation of the natural killer cell compartment during primary human immunodeficiency virus 1 infection primarily involving the CD56bright subset

    Science.gov (United States)

    Mantegani, Paola; Tambussi, Giuseppe; Galli, Laura; Din, Chiara Tassan; Lazzarin, Adriano; Fortis, Claudio

    2010-01-01

    We investigated the distribution of natural killer (NK) cell subsets, their activating and inhibitory receptors, and their cytolytic potential, in primary human immunodeficiency virus (HIV)-infected (PHI) individuals at baseline and during 1 year of follow-up with or without antiretroviral therapy, and compared the results with those obtained in treatment-naïve, chronically HIV-infected (CHI) individuals, and HIV-seronegative (HN) healthy individuals. The proportion of the CD56dim and CD56bright subsets decreased with disease progression, whereas that of the CD56− CD16+ subset increased. In the CD56dim subset, the proportion of cells with natural cytotoxicity receptors (NCRs) decreased with disease progression, and their cytolytic potential was reduced. Conversely, the CD56bright subset was characterized by a high proportion of NCR-positive, killer cell immunoglobulin-like receptor (KIR)-positive NKG2A+ cells in both CHI and PHI individuals, which was associated with an increase in their cytolytic potential. During the 1 year of follow-up, the PHI individuals with high viraemia levels and low CD4+ T-cell counts who received highly active antiretroviral therapy (HAART) had a similar proportion of NK subsets to CHI individuals, while patients with low viraemia levels and high CD4+ T-cell counts who remained untreated had values similar to those of the HN individuals. Our results indicate a marked perturbation of the NK cell compartment during HIV-1 infection that is multifaceted, starts early and is progressive, primarily involves the CD56bright subset, and is partially corrected by effective HAART. PMID:19824914

  11. Nonlinear cell response to strong electric fields

    Science.gov (United States)

    Bardos, D. C.; Thompson, C. J.; Yang, Y. S.; Joyner, K. H.

    2000-07-01

    The response of living cells to externally applied electric fields is of widespread interest. In particular, the intensification of electric fields across cell membranes is believed to be responsible, through membrane rupture and reversible membrane breakdown processes, for certain types of tissue damage in electrical trauma cases which cannot be attributed to Joule heating. Large elongated cells such as skeletal muscle fibres are particularly vulnerable to such damage. Previous theoretical studies of field intensification across cell membranes in such cells have assumed the membrane current to be linear in the applied field (Ohmic membrane conductivity) and were limited to sinusoidal applied fields. In this paper, we investigate a simple model of a long cylindrical cell, corresponding to nerve or skeletal muscle cells. Employing the electroquasistatic approximation, a system of coupled first-order differential equations for the membrane electric field is derived which incorporates arbitrary time dependence in the external field and nonlinear membrane response (non-Ohmic conductivity). The behaviour of this model is investigated for a variety of applied fields in both the linear and highly nonlinear regimes. We find that peak membrane fields predicted by the nonlinear model are approximately twice as intense, for low-frequency electrical trauma conditions, as those of the linear theory.

  12. Alamethicin permeabilizes the plasma membrane and mitochondria but not the tonoplast in tobacco (Nicotiana tabacum L. cv Bright Yellow) suspension cells

    DEFF Research Database (Denmark)

    Matic, S.; Geisler, D.A.; Møller, I.M.;

    2005-01-01

    The ion channel-forming peptide AlaM (alamethicin) is known to permeabilize isolated mitochondria as well as animal cells. When intact tobacco (Nicotiana tabacum L.) Bright Yellow-2 cells were treated with AlaM, the cells became permeable for low-molecular-mass molecules as shown by induced leakage...... remained intact, as indicated by an unaffected tonoplast proton gradient. Low-flux permeabilization of plasma membranes and mitochondria at moderate AlaM concentrations was reversible and did not affect cell vigour. Higher AlaM concentrations induced cell death. After the addition of catalase that removes...... the H2O2 necessary for NADH oxidation by apoplastic peroxidases, mitochondrial oxygen consumption could be measured in permeabilized cells. Inhibitor-sensitive oxidation of the respiratory substrates succinate, malate and NADH was observed after the addition of the appropriate coenzymes (ATP, NAD...

  13. The ESO key-programme "a homogeneous bright QSO survey"; 1, the methods and the "deep" fields

    CERN Document Server

    Cristiani, S; Andreani, P; Gemmo, A; Goldschmidt, P; Miller, L; Vio, R; Barbieri, C; Bodini, L; Iovino, A; Lazzarin, M; Clowes, R G; MacGillivray, H T; Gouiffes, C; Lissandrini, C; Savage, A

    1995-01-01

    This is the first paper in a series aimed at defining a statistically significant sample of QSOs in the range 15 < B < 18.75 and 0.3 < z < 2.2. The selection is carried out using direct plates obtained at the ESO and UK Schmidt Telescopes, scanned with the COSMOS facility and searched for objects with an ultraviolet excess. Follow-up spectroscopy, carried out at ESO La Silla, is used to classify each candidate. In this initial paper, we describe the scientific objectives of the survey; the selection and observing techniques used. We present the first sample of 285 QSOs (M_B < -23) in a 153 deg^2 area, covered by the six ``deep'' fields, intended to obtain significant statistics down B \\simeq 18.75 with unprecedented photometric accuracy. From this database, QSO counts are determined in the magnitude range 17 < B < 18.75.

  14. H-Band dropouts in the deepest CANDELS field. A new population of bright massive galaxies at z >3

    Science.gov (United States)

    Alcalde Pampliega, B.; Pérez-González, P. G.; Domínguez Sánchez, H.; Esquej, P.; Eliche-Moral, M. C.; Barro, G.

    2015-05-01

    The recent increase in depth, spatial and wavelength coverage of extragalactic surveys has improved dramatically our understanding of galaxy formation and evolution and is revealing a new population of galaxies at high redshift. That is consistent with a downsizing (Cowie, L. L., Songaila, A., Hu, E. M., & Cohen, J. G. 1996, AJ, 112, 839; Heavens, A., Panter, B., Jiménez, R., & Dunlop, J. 2004, Nature, 428, 625; Juneau, S., et al. 2005, ApJ, 619, L135; Bauer, A. E., Drory, N., Hill, G. J., & Feulner, G. 2005, ApJ, 621, L89; Pérez-González et al. 2008, ApJ, 675, 234) scenario, which implies that the most massive galaxies formed early in the history of the universe and evolved quickly. Red color criteria and the analysis of deep mid-IR, has been proven to very useful to identify high-z extremely red galaxies as shown in (Caputi, K. et al. 2012, ApJ, 750, L20 and Huang, J.-S., Zheng, X. Z., Rigopoulou, D. et al., 2011, ApJ, 742, L13). We present our analysis of the deepest near-infrared (F160W/H-band from CANDELS) and mid-infrared (IRAC from GOODS) data taken by HST and Spitzer (in the GOODS fields) to select sources only detected by IRAC and with no CANDELS counterpart (i.e., H>27, [3.6]≤25). These H-Band dropouts constitute a previously unknown population of dust-enshrouded and/or quiescent massive red galaxies at z>3. Using the wealth of data available in the GOODS field, especially the SHARDS data, we characterize the properties of this population of red galaxies and discuss on its relevance for previous estimations of the stellar mass function at z=3-5, and the evolution of massive galaxies in the early Universe.

  15. The Bright End of the z ∼ 9 and z ∼ 10 UV Luminosity Functions Using All Five CANDELS Fields*

    Science.gov (United States)

    Bouwens, R. J.; Oesch, P. A.; Labbé, I.; Illingworth, G. D.; Fazio, G. G.; Coe, D.; Holwerda, B.; Smit, R.; Stefanon, M.; van Dokkum, P. G.; Trenti, M.; Ashby, M. L. N.; Huang, J.-S.; Spitler, L.; Straatman, C.; Bradley, L.; Magee, D.

    2016-10-01

    The deep, wide-area (∼800–900 arcmin2) near-infrared/WFC3/IR + Spitzer/IRAC observations over the CANDELS fields have been a remarkable resource for constraining the bright end of high-redshift UV luminosity functions. However, the lack of Hubble Space Telescope (HST) 1.05 μm observations over the CANDELS fields has made it difficult to identify z ∼ 9–10 sources robustly, since such data are needed to confirm the presence of an abrupt Lyman break at 1.2 μm. Here, we report on the successful identification of many such z ∼ 9–10 sources from a new HST program (z9-CANDELS) that targets the highest-probability z ∼ 9–10 galaxy candidates with observations at 1.05 μm, to search for a robust Lyman-break at 1.2 μm. The potential z ∼ 9–10 candidates were preselected from the full HST, Spitzer/IRAC S-CANDELS observations, and the deepest-available ground-based optical+near-infrared observations (CFHTLS-DEEP+HUGS+UltraVISTA+ZFOURGE). We identified 15 credible z ∼ 9–10 galaxies over the CANDELS fields. Nine of these galaxies lie at z ∼ 9 and five are new identifications. Our targeted follow-up strategy has proven to be very efficient in making use of scarce HST time to secure a reliable sample of z ∼ 9–10 galaxies. Through extensive simulations, we replicate the selection process for our sample (both the preselection and follow-up) and use it to improve current estimates for the volume density of bright z ∼ 9 and z ∼ 10 galaxies. The volume densities we find are 5{}-2+3× and {8}-3+9× lower, respectively, than those found at z ∼ 8. When compared with the best-fit evolution (i.e., d {{log}}10 {ρ }{UV}/{dz}=-0.29+/- 0.02) in the UV luminosity densities from z ∼ 8 to z ∼ 4 integrated to 0.3{L}z=3* (‑20 mag), these luminosity densities are {2.6}-0.9+1.5× and {2.2}-1.1+2.0× lower, respectively, than the extrapolated trends. Our new results are broadly consistent with the “accelerated evolution” scenario at z > 8, consistent with

  16. The 2MASS Wide-Field T Dwarf Search. I. Discovery of a Bright T Dwarf Within 10 pc of the Sun

    CERN Document Server

    Burgasser, A J; McElwain, M W; Cutri, R M; Burgasser, A J; Skrutskie, M F; Burgasser, Adam J.; Elwain, Michael W. Mc; Cutri, Roc M.; Burgasser, Albert J.

    2002-01-01

    We present the discovery of a bright (J = 13.94$\\pm$0.03) T dwarf, 2MASS 1503+2525, identified in a new, wide-field search for T dwarfs using the recently completed Two Micron All Sky Survey (2MASS). The 1--2.5 $\\micron$ spectrum of this object exhibits the strong H$_2$O and CH$_4$ bands characteristic of mid- and late-type T dwarfs, and we derive a spectral type of T5.5 using both the Burgasser et al. and the Geballe et al. classification schemes. Based on its spectral type and the absolute magnitudes of known T dwarfs, we estimate the distance of this object as 8$\\pm$3 pc if it is single, likely within 10 pc of the Sun. Our new 2MASS search, which covers 74% of the sky and greatly expands on earlier color constraints, should identify 15--25 new T dwarfs with J $\\leq$ 16. Combined with the 20 known members of this class that already fall within our search criteria, our new sample will provide improved statistics for such key quantities as the binary fraction and the field substellar mass function. Furthermor...

  17. Increase in Peripheral CD3-CD56brightCD16- Natural Killer Cells in Hashimoto's Thyroiditis Associated with HHV-6 Infection.

    Science.gov (United States)

    Rizzo, Roberta; Zatelli, Maria Chiara; Rotola, Antonella; Cassai, Enzo; Degli Uberti, Ettore; Di Luca, Dario; Caselli, Elisabetta

    2016-01-01

    Hashimoto's thyroiditis (HT) is a very common autoimmune disease of the thyroid. In addition to genetic background, several viruses, including herpesviruses, have been suggested to play a role as possible environmental triggers of disease, but conclusive data are still lacking. Previous results showed that HT patients have an increased cellular immune response directed against the HHV-6 U94 protein and increased NK activity directed against HHV-6 infected thyrocytes.In this study, we characterized the antiviral antibody response and the NK cells activity and subtype in HHV-6 infected HT patients. The results showed that HT subjects have increased prevalence and titer of anti-U94 antibodies and a higher amount of CD3-CD56(bright)CD16(-)NK cell percentages compared to controls. Furthermore, the cell activation of CD3(-)CD56(bright) NK cells in HT patients significantly correlates with TPO and Tg Ab levels.The results suggest that HHV-6 might contribute to HT development, increasing NK cell secretion of inflammatory cytokines that could sustain the persistence of an inflammatory status in HT patients. PMID:26566646

  18. Detection of an ultra-bright submillimeter galaxy in the Subaru/XMM-Newton Deep Field using AzTEC/ASTE

    CERN Document Server

    Ikarashi, S; Aguirre, J E; Aretxaga, I; Arumugam, V; Austermann, J E; Bock, J J; Bradford, C M; Cirasuolo, M; Earle, L; Ezawa, H; Furusawa, H; Furusawa, J; Glenn, J; Hatsukade, B; Hughes, D H; Iono, D; Ivison, R J; Johnson, S; Kamenetzky, J; Kawabe, R; Lupu, R; Maloney, P; Matsuhara, H; Mauskopf, P D; Motohara, K; Murphy, E J; Nakajima, K; Nakanishi, K; Naylor, B J; Nguyen, H T; Perera, T A; Scott, K S; Takagi, T; Takata, T; Tamura, Y; Tanaka, K; Tsukagoshi, T; Wilner, D J; Wilson, G W; Yun, M S; Zmuidzinas, J

    2010-01-01

    We report the detection of an extremely bright ($\\sim$34 mJy at 1100 $\\mu$m and $\\sim$73 mJy at 880 $\\mu$m) submillimeter galaxy (SMG), AzTEC-ASTE-SXDF1100.001 (hereafter referred to as SXDF1100.001), discovered in 1100 $\\mu$m observations of the Subaru/XMM-Newton Deep Field using AzTEC on ASTE. Subsequent CARMA 1300 $\\mu$m and SMA 880 $\\mu$m observations successfully pinpoint the location of SXDF1100.001 and suggest that it has two components, extended (FWHM of $\\sim$4^{\\prime\\prime}) and compact (unresolved) ones. Z-Spec on CSO has also been used to obtain a wide band spectrum from 190 to 308 GHz, although no significant emission/absorption lines are found. The derived upper limit to the line-to-continuum flux ratio is 0.1--0.3 (2 $\\sigma$) across the Z-Spec band. Based on the analysis of the derived spectral energy distribution from optical to radio wavelengths of possible counterparts near the SMA/CARMA peak position, we suggest that SXDF1100.001 is a lensed, optically dark SMG lying at $z \\sim 3.4$ behin...

  19. The optical spectra of Spitzer 24 micron galaxies in the COSMOS field: II. Faint infrared sources in the zCOSMOS-bright 10k catalogue

    CERN Document Server

    Caputi, K I; Aussel, H; Le Floc'h, E; Sanders, D; Maier, C; Frayer, D; Carollo, C M; Contini, T; Kneib, J -P; Le Fèvre, O; Mainieri, V; Renzini, A; Scodeggio, M; Scoville, N; Zamorani, G; Bardelli, S; Bolzonella, M; Bongiorno, A; Coppa, G; Cucciati, O; De la Torre, S; de Ravel, L; Franzetti, P; Garilli, B; Ilbert, O; Iovino, A; Kampczyk, P; Kartaltepe, J; Knobel, C; Kovac, K; Lamareille, F; Le Borgne, J F; Le Brun, V; Mignoli, M; Peng, Y; Pérez-Montero, E; Ricciardelli, E; Salvato, M; Silverman, Joseph; Surace, J; Tanaka, M; Tasca, L; Tresse, L; Vergani, D; Zucca, E; Abbas, U; Bottini, D; Capak, P; Cappi, A; Cassata, P; Cimatti, A; Elvis, M; Hasinger, G; Koekemoer, A M; Leauthaud, A; MacCagni, D; Marinoni, C; McCracken, H; Memeo, P; Meneux, B; Oesch, P; Pellò, R; Porciani, C; Pozzetti, L; Scaramella, R; Scarlata, C; Schiminovich, D; Taniguchi, Y; Zamojski, M

    2009-01-01

    We have used the zCOSMOS-bright 10k sample to identify 3244 Spitzer/MIPS 24-micron-selected galaxies with 0.06< S(24um)< 0.50 mJy and I(AB)<22.5, over 1.5 deg^2 of the COSMOS field, and studied different spectral properties, depending on redshift. At 0.2

  20. Wide Integral-Field Infrared Spectroscopy of the Bright [Fe II] Shell in the Young Supernova Remnant G11.2-0.3

    CERN Document Server

    Lee, Ho-Gyu; Koo, Bon-Chul; Rahman, Mubdi; Eikenberry, Stephen S; Gruel, Nicolas; Onaka, Takashi; Kim, Hyun-Jeong; Chun, Won-Seok; Raymond, J C; Raines, S Nicholas; Guzman, Rafael

    2013-01-01

    We present the results of wide integral-field near-infrared (1.0-1.8 um) spectroscopic observations of the southeastern shell of the young core-collapse supernova remnant (SNR) G11.2-0.3. We first construct [Fe II] 1.644 um line images of three bright clumps from the obtained spectral image cubes and compare them with those of other transitions such as [Fe II] 1.257, [Fe II] 1.534 and He I 1.083 um line images. This allows us to estimate the electron density (~ 4,700-9,400 cm^-3) and extinction (Av ~ 16-20 mag) of the shell, including detailed two-dimensional distribution of the properties in the brightest clump, as well as the discovery of a faint high-velocity (~ -440 km/s) component in the clump. Our SNR shock model calculations estimate the preshock number density of ~ 250-500 cm^-3 and shock speed of ~ 80-250 km/s in the [Fe II]-emitting region of the SNR. The comparison between the observed and modelled radial profiles of the line intensities and their ratios reveals that the shell is composed of multip...

  1. Burkina Faso - BRIGHT II

    Data.gov (United States)

    Millenium Challenge Corporation — Millennium Challenge Corporation hired Mathematica Policy Research to conduct an independent evaluation of the BRIGHT II program. The three main research questions...

  2. Haemopoietic cell renewal in radiation fields.

    Science.gov (United States)

    Fliedner, T M; Nothdurft, W; Tibken, B; Hofer, E; Weiss, M; Kindler, H

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a "turbulence region" for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a "blood stem cell bank" might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container. PMID:11539991

  3. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  4. Spatial Brightness Perception of Trichromatic Stimuli

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Houser, Kevin W.

    2012-11-16

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

  5. Spectroscopic Surface Brightness Fluctuations: Amplifying Bright Stars in Unresolved Stellar Populations

    Science.gov (United States)

    Mitzkus, M.; Dreizler, S.; Roth, M. M.

    2015-08-01

    We report on our early-stage efforts to resolve the Surface Brightness Fluctuations (SBFs) in the spectral dimension. Combining the diagnostic power of SBFs with the physical information content of spectra seems a tempting possibility to gain new insights into the bright stars in unresolved stellar populations. The new VLT integral field spectrograph MUSE is the first instrument that enables spectroscopic SBFs observationally.

  6. Bright fluorescence monitoring system utilizing Zoanthus sp. green fluorescent protein (ZsGreen for human G-protein-coupled receptor signaling in microbial yeast cells.

    Directory of Open Access Journals (Sweden)

    Yasuyuki Nakamura

    Full Text Available G-protein-coupled receptors (GPCRs are currently the most important pharmaceutical targets for drug discovery because they regulate a wide variety of physiological processes. Consequently, simple and convenient detection systems for ligands that regulate the function of GPCR have attracted attention as powerful tools for new drug development. We previously developed a yeast-based fluorescence reporter ligand detection system using flow cytometry. However, using this conventional detection system, fluorescence from a cell expressing GFP and responding to a ligand is weak, making detection of these cells by fluorescence microscopy difficult. We here report improvements to the conventional yeast fluorescence reporter assay system resulting in the development of a new highly-sensitive fluorescence reporter assay system with extremely bright fluorescence and high signal-to-noise (S/N ratio. This new system allowed the easy detection of GPCR signaling in yeast using fluorescence microscopy. Somatostatin receptor and neurotensin receptor (implicated in Alzheimer's disease and Parkinson's disease, respectively were chosen as human GPCR(s. The facile detection of binding to these receptors by cognate peptide ligands was demonstrated. In addition, we established a highly sensitive ligand detection system using yeast cell surface display technology that is applicable to peptide screening, and demonstrate that the display of various peptide analogs of neurotensin can activate signaling through the neurotensin receptor in yeast cells. Our system could be useful for identifying lead peptides with agonistic activity towards targeted human GPCR(s.

  7. High-brightness electron injectors

    International Nuclear Information System (INIS)

    Free-electron laser (FEL) oscillators and synchrotron light sources require pulse trains of high peak brightness and, in some applications, high-average power. Recent developments in the technology of photoemissive and thermionic electron sources in rf cavities for electron-linac injector applications offer promising advances over conventional electron injectors. Reduced emittance growth in high peak-current electron injectors may be achieved by using high field strengths and by linearizing the radial component of the cavity electric field at the expense of lower shunt impedance

  8. Helmholtz bright and boundary solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2007-02-16

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts.

  9. On the use of GNSS-R data to correct L-band brightness temperatures for sea-state effects: results of the ALBATROSS field experiments

    OpenAIRE

    Valencia Domènech, Enric; Camps Carmona, Adriano José; Bosch Lluís, Xavier; Rodríguez Álvarez, Nereida; Ramos Pérez, Isaac; Eugenio, Francisco Javier; Marcello, Javier

    2011-01-01

    Sea surface salinity is a key oceanographic parameter that can be measured by means of L-band microwave radiometry. The measured brightness temperatures over the ocean are influenced by the sea state, which can entirely mask the salinity signature. Sea-state corrections parameterized in terms of wind speed and/or significant wave height have proven not to be fully satisfactory. In 2003, it was proposed to use reflectometry using navigation opportunity signals [Global Navigation Satellite S...

  10. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called `depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. I...

  11. How can Fuel Cell Vehicles bring a bright future for this Dragon? Answer by Multi-criteria Decision Making Analysis

    DEFF Research Database (Denmark)

    Zhang, Long; Yu, Jing; Ren, Jingzheng;

    2016-01-01

    . By using Fishbone Diagram, field survey and workshop discussions, this paper proposes a group of factors that may affect customers’ preferences on FCVs. Furthermore, Fuzzy AHP and Pareto Analysis are employed to prioritize these factors, and identify the critical ones. The results indicate that fuel...

  12. How can Fuel Cell Vehicles bring a bright future for this Dragon? Answer by Multi-criteria Decision Making Analysis

    DEFF Research Database (Denmark)

    Zhang, Long; Yu, Jing; Ren, Jingzheng;

    2016-01-01

    Fuel Cell Vehicles (FCVs) has been introduced to the market around the world in recent years. As the largest automobile market of the world, China is also one of the potential FCVs market. However, a series of factors and barriers influence the willingness of China’s customers to accept FCVs. By ...

  13. Production of Reactive Oxygen Species, Alteration of Cytosolic Ascorbate Peroxidase, and Impairment of Mitochondrial Metabolism Are Early Events in Heat Shock-Induced Programmed Cell Death in Tobacco Bright-Yellow 2 Cells1

    Science.gov (United States)

    Vacca, Rosa Anna; de Pinto, Maria Concetta; Valenti, Daniela; Passarella, Salvatore; Marra, Ersilia; De Gara, Laura

    2004-01-01

    To gain some insight into the mechanisms by which plant cells die as a result of abiotic stress, we exposed tobacco (Nicotiana tabacum) Bright-Yellow 2 cells to heat shock and investigated cell survival as a function of time after heat shock induction. Heat treatment at 55°C triggered processes leading to programmed cell death (PCD) that was complete after 72 h. In the early phase, cells undergoing PCD showed an immediate burst in hydrogen peroxide (H2O2) and superoxide (O2·-) anion production. Consistently, death was prevented by the antioxidants ascorbate (ASC) and superoxide dismutase (SOD). Actinomycin D and cycloheximide, inhibitors of transcription and translation, respectively, also prevented cell death, but with a lower efficiency. Induction of PCD resulted in gradual oxidation of endogenous ASC; this was accompanied by a decrease in both the amount and the specific activity of the cytosolic ASC peroxidase (cAPX). A reduction in cAPX gene expression was also found in the late PCD phase. Moreover, changes of cAPX kinetic properties were found in PCD cells. Production of ROS in PCD cells was accompanied by early inhibition of glucose (Glc) oxidation, with a strong impairment of mitochondrial function as shown by an increase in cellular NAD(P)H fluorescence, and by failure of mitochondria isolated from cells undergoing PCD to generate membrane potential and to oxidize succinate in a manner controlled by ADP. Thus, we propose that in the early phase of tobacco Bright-Yellow 2 cell PCD, ROS production occurs, perhaps because of damage of the cell antioxidant system, with impairment of the mitochondrial oxidative phosphorylation. PMID:15020761

  14. Bright Metal-Poor Stars from the Hamburg/ESO Survey. I. Selection and Follow-up Observations from 329 Fields

    CERN Document Server

    Frebel, A; Norris, J E; Beers, T C; Bessell, M S; Rhee, J; Fechner, C; Marsteller, B; Rossi, S; Thom, C; Wisotzki, L; Reimers, D

    2006-01-01

    We present a sample of 1777 bright (91.0) metal-poor ([Fe/H]20%) and higher values with increasing distance from the Galactic plane. Although the numbers of stars at low metallicity are falling rapidly at the lowest metallicities, there is evidence that the fraction of carbon-enhanced metal-poor stars is increasing rapidly as a function of declining metallicity. For ~60 objects, high-resolution data have already been obtained; one of these, HE 1327-2326, is the new record holder for the most iron-deficient star known.

  15. Research on Brightness Measurement of Intense Electron Beam

    CERN Document Server

    Wang, Yuan; Zhang, Huang; Yang, GuoJun; Li, YiDing; Li, Jin

    2015-01-01

    The mostly research fasten on high emission density of injector to study electron beam's brightness in LIA. Using the injector(2MeV) was built to research brightness of multi-pulsed high current(KA) electron beam, and researchs three measurement method (the pepper-pot method, beam collimator without magnetic field, beam collimator with magnetic field method) to detect beam's brightness with time-resolved measurement system.

  16. The role of the Fraunhofer lines in solar brightness variability

    CERN Document Server

    Shapiro, A I; Krivova, N A; Tagirov, R V; Schmutz, W K

    2015-01-01

    The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the solar-terrestrial and solar-stellar connections. We estimate the relative contributions of the continuum, molecular, and atomic lines to the solar brightness variations on different timescales. Our approach is based on the assumption that variability of the solar brightness on timescales greater than a day is driven by the evolution of the solar surface magnetic field. We calculated the solar brightness variations employing the solar disc area coverage of magnetic features deduced from the MDI/SOHO observations. The brightness contrasts of magnetic features relative to the quiet Sun were calculated with a non-LTE radiative transfer code as functions of disc position and waveleng...

  17. Inhibition of brain tumor cell proliferation by alternating electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyesun; Oh, Seung-ick; Hong, Sunghoi, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [School of Biosystem and Biomedical Science, Korea University, Seoul 136-703 (Korea, Republic of); Sung, Jiwon; Jeong, Seonghoon; Yoon, Myonggeun, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [Department of Bio-convergence Engineering, Korea University, Seoul 136-703 (Korea, Republic of); Koh, Eui Kwan [Seoul Center, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of)

    2014-11-17

    This study was designed to investigate the mechanism by which electric fields affect cell function, and to determine the optimal conditions for electric field inhibition of cancer cell proliferation. Low-intensity (<2 V/cm) and intermediate-frequency (100–300 kHz) alternating electric fields were applied to glioblastoma cell lines. These electric fields inhibited cell proliferation by inducing cell cycle arrest and abnormal mitosis due to the malformation of microtubules. These effects were significantly dependent on the intensity and frequency of applied electric fields.

  18. The influence of electric field and confinement on cell motility.

    Directory of Open Access Journals (Sweden)

    Yu-Ja Huang

    Full Text Available The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.

  19. The influence of electric field and confinement on cell motility.

    Science.gov (United States)

    Huang, Yu-Ja; Samorajski, Justin; Kreimer, Rachel; Searson, Peter C

    2013-01-01

    The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.

  20. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available BACKGROUND: The perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this 'illusion' to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies. RESULTS: Rather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1, if not earlier in the visual system, since the brightness of colours (as opposed to their luminance accords with activity in V1 as measured with fMRI. CONCLUSIONS: The data suggest that perceptions

  1. CA BrightStor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CA推出的BrightStor系列存储管理解决方案已经成为企业电子商务体系架构管理战略中举足轻重的组成部分。BrightStor是一整套企业级的智能化存储管理解决方案,定位在存储硬件设备和上层应用之间,通过各种集成化的产品和工具为驻留在企业任何位置的数据提供全方位的、有效的存储管理和保护。

  2. Bright Economic Prospects

    Institute of Scientific and Technical Information of China (English)

    Zhang Minqiu

    2004-01-01

    @@ India is expected to register an 8.2% growth rate for the 2003-04 fiscal year. The overall economic situation this year has been satisfactory despite the scaled down 6-6.5% growth rate for the new fiscal year due to oil price hikes, reduced monsoon volume and some 7% inflation. Judging from the following factors, bright prospects are in store for the country down the road.

  3. Low surface brightness galaxies

    Science.gov (United States)

    Vanderhulst, J. M.; Deblok, W. J. G.; Mcgaugh, S. S.; Bothun, G. D.

    1993-01-01

    A program to investigate the properties of low surface brightness (LSB) galaxies involving surface photometry in U, B, V, R, I, and H-alpha, HI imaging with the Westerbork Synthesis Radio Telescope (WSRT) and the very large array (VLA) and spectrophotometry of H2 regions in LSB galaxies is underway. The goal is to verify the idea that LSB galaxies have low star formation rates because the local gas density falls below the critical density for star formation, and to study the stellar population and abundances in LSB galaxies. Such information should help understanding the evolutionary history of LSB galaxies. Some preliminary results are reported.

  4. Cytochrome c Is Released in a Reactive Oxygen Species-Dependent Manner and Is Degraded via Caspase-Like Proteases in Tobacco Bright-Yellow 2 Cells en Route to Heat Shock-Induced Cell Death1

    Science.gov (United States)

    Vacca, Rosa Anna; Valenti, Daniela; Bobba, Antonella; Merafina, Riccardo Sandro; Passarella, Salvatore; Marra, Ersilia

    2006-01-01

    To gain some insight into the mechanism of plant programmed cell death, certain features of cytochrome c (cyt c) release were investigated in heat-shocked tobacco (Nicotiana tabacum) Bright-Yellow 2 cells in the 2- to 6-h time range. We found that 2 h after heat shock, cyt c is released from intact mitochondria into the cytoplasm as a functionally active protein. Such a release did not occur in the presence of superoxide anion dismutase and catalase, thus showing that it depends on reactive oxygen species (ROS). Interestingly, ROS production due to xanthine plus xanthine oxidase results in cyt c release in sister control cultures. Maximal cyt c release was found 2 h after heat shock; later, activation of caspase-3-like protease was found to increase with time. Activation of this protease did not occur in the presence of ROS scavenger enzymes. The released cyt c was found to be progressively degraded in a manner prevented by either the broad-range caspase inhibitor (zVAD-fmk) or the specific inhibitor of caspase-3 (AC-DEVD-CHO), which have no effect on cyt c release. In the presence of these inhibitors, a significant increase in survival of the cells undergoing programmed cell death was found. We conclude that ROS can trigger release of cyt c, but do not cause cell death, which requires caspase-like activation. PMID:16531480

  5. Moon night sky brightness simulation for the Xinglong station

    International Nuclear Information System (INIS)

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

  6. Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Hur

    Full Text Available The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

  7. Nanotomography of Cell Surfaces with Evanescent Fields

    Directory of Open Access Journals (Sweden)

    Michael Wagner

    2008-01-01

    Full Text Available The technique of variable-angle total internal reflection fluorescence microscopy (TIRFM and its application to nanotomography of cell surfaces are described. Present applications include (1 3D imaging of chromosomes in their metaphase to demonstrate axial resolution in the nanometre range, (2 measurements of cell-substrate topology, which upon cholesterol depletion shows some loosening of cell-substrate contacts, and (3 measurements of cell topology upon photodynamic therapy (PDT, which demonstrate cell swelling and maintenance of focal contacts. The potential of the method for in vitro diagnostics, but also some requirements and limitations are discussed.

  8. Migration of amoeba cells in an electric field

    Science.gov (United States)

    Guido, Isabella; Bodenschatz, Eberhard

    2015-03-01

    Exogenous and endogenous electric fields play a role in cell physiology as a guiding mechanism for the orientation and migration of cells. Electrotaxis of living cells has been observed for several cell types, e.g. neurons, fibroblasts, leukocytes, neural crest cells, cancer cells. Dictyostelium discoideum (Dd), an intensively investigated chemotactic model organism, also exhibits a strong electrotactic behavior moving toward the cathode under the influence of electric fields. Here we report experiments on the effects of DC electric fields on the directional migration of Dd cells. We apply the electric field to cells seeded into microfluidic devices equipped with agar bridges to avoid any harmful effects of the electric field on the cells (ions formation, pH changes, etc.) and a constant flow to prevent the build-up of chemical gradient that elicits chemotaxis. Our results show that the cells linearly increase their speed over time when a constant electric field is applied for a prolonged duration (2 hours). This novel phenomenon cannot be attributed to mechanotaxis as the drag force of the electroosmotic flow is too small to produce shear forces that can reorient cells. It is independent of the cellular developmental stage and to our knowledge, it was not observed in chemotaxis. This work is supported by MaxSynBio project of the Max Planck Society.

  9. Most Luminous z=9-10 Galaxies: A First Determination of the Bright End of the z~9 and z~10 UV Luminosity Functions using all five CANDELS Fields

    CERN Document Server

    Bouwens, R J; Labbe, I; Illingworth, G D; Fazio, G; Coe, D; Holwerda, B; Smit, R; Stefanon, M; van Dokkum, P G; Trenti, M; Ashby, M; Huang, J; Spitler, L; Straatman, C; Bradley, L; Magee, D

    2015-01-01

    The deep, wide-area (900 arcmin**2) near-IR/WFC3/IR + Spitzer/IRAC observations over the CANDELS program represents a significant resource for constraining the bright end of the z~9 and z~10 luminosity functions (LFs) in the UV. We recently reported the discovery of 6 luminous z~9-10 candidates over the GOODS-North+South fields, but extending this search to the full CANDELS program was limited due to the lack of HST-depth 1.05-micron observations in the other 3 CANDELS fields. Here we attempt to significantly realize the potential of CANDELS for z=9-10 science by combining a search over all 5 fields with results from a new HST program (B9-CANDELS) designed to follow up the highest-probability z~9-10 galaxy candidates with observations at 1.05 microns. The targeted z~9-10 candidates are preselected by taking advantage of the full HST, Spitzer/IRAC S-CANDELS observations, and the deepest-available ground-based optical+near-IR observations. With our follow-up program now 91% complete, we identify 4 new high-prob...

  10. Brightness of synchrotron radiation from wigglers

    Science.gov (United States)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2016-01-01

    According to the literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so-called 'depth-of-field' effects. In fact, the particle beam cross-section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. We exemplify this formalism in simple limiting cases. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in the literature.

  11. How Bright Can Supernovae Get?

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  12. The Influence of Brightness on Functional Assessment by mfERG: A Study on Scaffolds Used in Retinal Cell Transplantation in Pigs

    Directory of Open Access Journals (Sweden)

    A. T. Christiansen

    2012-01-01

    Full Text Available To determine the effect of membrane brightness on multifocal electroretinograms (mfERGs, we implanted poly lactic-co-glycolic acid (PLGA membranes in the subretinal space of 11 porcine eyes. We compared membranes with their native shiny white color with membranes that were stained with a blue dye (Brilliant Blue. Histological and electrophysiological evaluation of the overlying retina was carried out 6 weeks after implantation. Histologically, both white and blue membranes degraded in a spongiform manner leaving a disrupted outer retina with no preserved photoreceptor segments. Multifocal ERG revealed the white membranes to have a significantly higher P1-amplitude ratio than the blue (P=0.027, and a correlation between brightness ratio and P1-amplitude ratio was found (r=0.762. Based on our findings, we conclude that bright subretinal objects can produce normal mfERG amplitude ratios even when the adjacent photoreceptors are missing. Functional assessment with mfERG in scaffold implant studies should therefore be evaluated with care.

  13. HAT-P-56b: A bright highly inflated massive Hot Jupiter around An F star in K2.0 field

    Science.gov (United States)

    Huang, Xu; Bakos, Gaspar; Hartman, Joel

    2015-08-01

    We report the discovery of HAT-P-56b, a transiting high inflated hot-jupiter orbiting a F type star in the field 0 of the NASA K2 mission, by the HATNet survey. We combine ground-based photometric light curves with the highprecision photometry obervation by the K2 mission, as well as radial velocity to determine the physical properties of this system. HAT-P-56b has a mass around ~2.2 Mjunp, a radius of ~1.5 Rjup, and transits its host star with a period of 2.79d. The host star has a V band magnitude of 10.9, Mass of 1.29 Msun, and radius of 1.433 Rsun. The radius of HAT-P-56b is among one of the largest compare to planets with similar mass, making it an interesting target for following up atmospherical observations.

  14. Changes in the Antioxidant Systems as Part of the Signaling Pathway Responsible for the Programmed Cell Death Activated by Nitric Oxide and Reactive Oxygen Species in Tobacco Bright-Yellow 2 Cells1

    Science.gov (United States)

    de Pinto, Maria Concetta; Tommasi, Franca; De Gara, Laura

    2002-01-01

    Nitric oxide (NO) has been postulated to be required, together with reactive oxygen species (ROS), for the activation of the hypersensitive reaction, a defense response induced in the noncompatible plant-pathogen interaction. However, its involvement in activating programmed cell death (PCD) in plant cells has been questioned. In this paper, the involvement of the cellular antioxidant metabolism in the signal transduction triggered by these bioactive molecules has been investigated. NO and ROS levels were singularly or simultaneously increased in tobacco (Nicotiana tabacum cv Bright-Yellow 2) cells by the addition to the culture medium of NO and/or ROS generators. The individual increase in NO or ROS had different effects on the studied parameters than the simultaneous increase in the two reactive species. NO generation did not cause an increase in phenylalanine ammonia-lyase (PAL) activity or induction of cellular death. It only induced minor changes in ascorbate (ASC) and glutathione (GSH) metabolisms. An increase in ROS induced oxidative stress in the cells, causing an oxidation of the ASC and GSH redox pairs; however, it had no effect on PAL activity and did not induce cell death when it was generated at low concentrations. In contrast, the simultaneous increase of NO and ROS activated a process of death with the typical cytological and biochemical features of hypersensitive PCD and a remarkable rise in PAL activity. Under the simultaneous generation of NO and ROS, the cellular antioxidant capabilities were also suppressed. The involvement of ASC and GSH as part of the transduction pathway leading to PCD is discussed. PMID:12376637

  15. Effect of Magnetic Field on L-Strain Cells

    CERN Document Server

    Ulakoglu, G; Atak, C; Rzakoulieva, A; Danilov, V I; Alikamanoglu, S

    2000-01-01

    The effects of electromagnetic and magnetic fields are currently being made useful in many fields, especially in medicine. In this research work, L-Strain cells which are a type of fibrosarcoma cells were exposed to a magnetic flow of 2-26 mT in periods of 1, 2, 3 and 4 minutes. The L-Strain cells, which were exposed to the magnetic field for these periods, were counted after 24 and 48 hours, when compared with the controls, it was observed that in groups of 1 and 4 minutes exposure a significant decrease (P < 0.05) in the number of cells occurred. The per cent of labelling index of L-Strain cells exposed to the magnetic field for 1 and 4 minutes decreased significantly also in comparison to the controls.

  16. Effects of Magnetic Field on Biological Cells and Applications

    Science.gov (United States)

    Chen, Ching-Jen

    2001-03-01

    While there has been extensive research performed in the physics of magnetic fields and the physics and chemistry in life sciences, independent of each other, there has been a paucity of scientific research and development investigating the possible applications of magnetic fields in life sciences. The focus of this presentation is to present the stimulation mechanism by which magnetic fields affect (a) yeast cells (b) plant cells and (c) mammalian normal and cancer cells. Recently we have found that the Saccharomyces Cerevsa yeast growth increases by about 30to a 1 tesla field and the production of CO2 increases by about 30of yeast metabolism may be due to an increase in intercellular interaction and protein channel alignment, the introduction of an alteration in the DNA from the magnetic field exposure or a combination of these mechanisms. We also have found that the application of high magnetic fields (1 tesla and above) can have marked effects on the germination and growth of plants, especially corn, beans and peas. This finding has opened up the possibility of technology developments in botanical growth systems to accelerate seed germination and crop harvesting. Most recently we have investigated the application of high magnetic fields on leukemia, CaCoII and HEP G2 cancer cell lines. We found that when leukemia are exposed to a 12 tesla field for 2 hours has an increase in cell death by about 30that were not exposed to the magnetic field. Viability of CaCoII cells sandwiched between permanent magnets of maximum strength of 1.2 tesla was measured. A decrease in viable cells by 33unexposed cells. HSP 70 was measured for HEPG2 cells that were exposed to permanent magnetic field of 1.2 tesla for 40 minutes and for unexposed cells. It was found that the exposed cells produce 19 times more HSP70 compared to unexposed cells. Our results together with other investigators report suggest a strong evidence of a reduction in the cell growth rate for cancer cells when

  17. The relationship between brightness temperature and soil moisture. Selection of frequency range for microwave remote sensing

    International Nuclear Information System (INIS)

    The analysis of brightness temperature data acquired from field and aircraft experiments demonstrates a linear relationship between soil moisture and brightness temperature. However, the analysis of brightness temperature data acquired by the Skylab radiometer demonstrates a non-linear relationship between soil moisture and brightness temperature. In view of the above and also because of recent theoretical developments for the calculation of the dielectric constant and brightness temperature under varying soil moisture profile conditions, an attempt is made to study the theoretical relationship between brightness temperature and soil moisture as a function of frequency. Through the above analysis, the appropriate microwave frequency range for soil moisture studies is recommended

  18. Video Field Studies with your Cell Phone

    DEFF Research Database (Denmark)

    Buur, Jacob; Fraser, Euan

    2010-01-01

    Many researchers and practitioners in HCI, Interaction Design, Design Anthropology swear to video when dung field studies of potential users. This is due to the power of the media for capturing practices and contexts, conveying empathy, and engaging audiences. Newcomers to the field, and in parti......Many researchers and practitioners in HCI, Interaction Design, Design Anthropology swear to video when dung field studies of potential users. This is due to the power of the media for capturing practices and contexts, conveying empathy, and engaging audiences. Newcomers to the field......, and in particular practitioners from smaller organizations are understandably nervous about embarking on video projects out of fear that it is difficult to get consent in the first place, that the ethics is difficult to handle, that video shooting makes the social relations awkward, that the editing task......Pod? Or with the GoPRO sports camera? Our approach has a strong focus on how to use video in design, rather than on the technical side. The goal is to engage design teams in meaningful discussions based on user empathy, rather than to produce beautiful videos. Basically it is a search for a minimalist way...

  19. Bright Solitary Waves in Malignant Gliomas

    OpenAIRE

    Pérez-García, Víctor M.; Calvo, Gabriel F.; Belmonte-Beitia, Juan; Diego, D.; Pérez-Romasanta, Luis

    2011-01-01

    We put forward a nonlinear wave model describing the fundamental physio-pathologic features of an aggressive type of brain tumors: glioblastomas. Our model accounts for the invasion of normal tissue by a proliferating and propagating rim of active glioma cancer cells in the tumor boundary and the subsequent formation of a necrotic core. By resorting to numerical simulations, phase space analysis and exact solutions, we prove that bright solitary tumor waves develop in such systems.

  20. The LBT Boötes Field Survey. I. The Rest-frame Ultraviolet and Near-infrared Luminosity Functions and Clustering of Bright Lyman Break Galaxies at Z ~ 3

    Science.gov (United States)

    Bian, Fuyan; Fan, Xiaohui; Jiang, Linhua; McGreer, Ian; Dey, Arjun; Green, Richard F.; Maiolino, Roberto; Walter, Fabian; Lee, Kyoung-Soo; Davé, Romeel

    2013-09-01

    We present a deep LBT/LBC U spec-band imaging survey (9 deg2) covering the NOAO Boötes field. A total of 14,485 Lyman break galaxies (LBGs) at z ~ 3 are selected, which are used to measure the rest-frame UV luminosity function (LF). The large sample size and survey area reduce the LF uncertainties due to Poisson statistics and cosmic variance by >=3 compared to previous studies. At the bright end, the LF shows excess power compared to the best-fit Schechter function, which can be attributed to the contribution of z ~ 3 quasars. We compute the rest-frame near-infrared LF and stellar mass function (SMF) of z ~ 3 LBGs based on the R-band and [4.5 μm]-band flux relation. We investigate the evolution of the UV LFs and SMFs between z ~ 7 and z ~ 3, which supports a rising star formation history in the LBGs. We study the spatial correlation function of two bright LBG samples and estimate their average host halo mass. We find a tight relation between the host halo mass and the galaxy star formation rate (SFR), which follows the trend predicted by the baryonic accretion rate onto the halo, suggesting that the star formation in LBGs is fueled by baryonic accretion through the cosmic web. By comparing the SFRs with the total baryonic accretion rates, we find that cosmic star formation efficiency is about 5%-20% and it does not evolve significantly with redshift, halo mass, or galaxy luminosity. Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University

  1. On the origin of facular brightness

    CERN Document Server

    Kostik, R

    2016-01-01

    This paper studies the dependence of the CaIIH line core brightness on the strength and inclination of photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the solar disc center. We use three simultaneous datasets obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of BaII 4554 A line registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in FeI 1.56 $\\mu$m lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in CaIIH that give information about brightness fluctuations in the chromosphere. The results show that the CaIIH brightness in the facula strongly depends on the power of waves with periods in the 5-min range, that propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature min...

  2. Polymer electrolyte fuel cells: flow field for efficient air operation

    Energy Technology Data Exchange (ETDEWEB)

    Buechi, F.N.; Tsukada, A.; Haas, O.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    A new flow field was designed for a polymer electrolyte fuel cell stack with an active area of 200 cm{sup 2} for operation at low air stoichiometry and low air over pressure. Optimum of gas flow and channel dimensions were calculated based on the required pressure drop in the fluid. Single cells and a bi-cell stack with the new flow field show an improved current/voltage characteristic when operated at low air stoichiometries as compared to that of the previous non optimized design. (author) 4 figs., 3 refs.

  3. The bright optical flash from GRB 060117

    CERN Document Server

    Jel'inek, M; Kubánek, P; Hudec, R; Nekola, M; Grygar, J; Castro-Tirado, A J; Gorosabel, J; Hrabovsk'y, M; Mandat, D; Nosek, D; Palatka, M; Pandey, S B; Pech, M; Schovanek, P; De Postigo, A U; Vítek, S; Jel\\'inek, Martin; Prouza, Michael; Kub\\'anek, Petr; Hudec, Ren\\'e; Nekola, Martin; R}\\'idk\\'y, Jan {; Grygar, Ji{r}\\'i; Castro-Tirado, Alberto J.; Gorosabel, Javier; Hrabovsk\\'y, Miroslav; Mand\\'at, Du{s}an; Nosek, Dalibor; Palatka, Miroslav; Pandey, Shashi B.; Pech, Miroslav; Schov\\'anek, Petr; S}m\\'ida, Radom\\'ir {; Postigo, Antonio de Ugarte; V\\'itek, Stanislav

    2006-01-01

    We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.

  4. 高亮度场发射荧光灯的制备及其性能测试%Fabrication and Properties of High Brightness Field Emission Fluorescence Lamp

    Institute of Scientific and Technical Information of China (English)

    郑旭丹; 胡利勤; 郭太良

    2011-01-01

    利用圆柱形结构的增强效应能提高丝状阴极场发射性能的这个特性,设计了场发射荧光灯.采用热敷法将配制好的碳纳米管(Carbon Nanotubes,CNT)浆料转移到镍丝(Ni)表面制备成丝状阴极,以及溶胶-凝胶法在圆柱形玻璃管内壁制备掺锡氧化铟(Indium Tin Oxide,ITO)薄膜作为阳极,制作场发射荧光灯.测试结果表明,该碳纳米管场发射荧光灯具有良好的场发射性能,开启电场低,仅为0.15 V/μm;CNT的场增强因子βCNT为1967;当驱动电压为4 000 V时,发光亮度达19 800cd/m2.这种亮度高、稳定性好、成本低的场发射荧光灯在照明光源领域具有很大的应用前景.%A novel cylindrical geometry carbon nanotubes (CNT)field emission fluorescence lamp (FEFL)was designed. The CNT paste was transfered to the surface of the nickel wire by thermal coating method ,and the indium tin oxide(ITO) thin film was fabricated in the cylinder glass pipe by sol-gel. The cylinder glass pipe with ITO film and phosphor was used as anode. The FEFL showed superior properties,such as low turn-on electric field of 0.15 V/μm,high brightness of 19 800 cd/m2 at the voltage 4 000 V,and large field enhancement factor of 1967. The FEFL is a very promising candidate as back light source.

  5. High resolution field imaging with atomic vapor cells

    OpenAIRE

    Horsley, Andrew

    2015-01-01

    In this thesis, I report on the development of imaging techniques in atomic vapor cells. This is a relatively unexplored area, despite the ubiquitous use of imaging in experiments with ultracold atoms. Our main focus is in high resolution imaging of microwave near fields, for which there is currently no satisfactory established technique. We detect microwave fields through Rabi oscillations driven by the microwave on atomic hyperfine transitions. The technique can be easily modified to also i...

  6. Test chambers for cell culture in static magnetic field

    International Nuclear Information System (INIS)

    Article presents a test chamber intended to be used for in vitro cell culture in homogenous constant magnetic field with parametrically variable magnitude. We constructed test chambers with constant parameters of control homeostasis of cell culture for the different parameters of static magnetic field. The next step was the computer calculation of 2D and 3D simulation of the static magnetic field distribution in the chamber. The analysis of 2D and 3D calculations of magnetic induction in the cells' exposition plane reveals, in comparison to the detection results, the greater accuracy of 2D calculations (Figs. 9 and 10). The divergence in 2D method was 2–4% and 8 to 10% in 3D method (reaching 10% only out of the cells′ cultures margins). -- Highlights: ► We present test chamber to be used for in vitro cell culture in static magnetic field. ► The technical data of the chamber construction was presented. ► 2D versus 3D simulation of static magnetic field distribution in chamber was reported. ► We report the accuracy of 2D calculation than 3D

  7. Cell Survival and DNA Damage in Normal Prostate Cells Irradiated Out-of-Field.

    LENUS (Irish Health Repository)

    Shields, L

    2014-10-31

    Interest in out-of-field radiation dose has been increasing with the introduction of new techniques, such as volumetric modulated arc therapy (VMAT). These new techniques offer superior conformity of high-dose regions to the target compared to conventional techniques, however more normal tissue is exposed to low-dose radiation with VMAT. There is a potential increase in radiobiological effectiveness associated with lower energy photons delivered during VMAT as normal cells are exposed to a temporal change in incident photon energy spectrum. During VMAT deliveries, normal cells can be exposed to the primary radiation beam, as well as to transmission and scatter radiation. The impact of low-dose radiation, radiation-induced bystander effect and change in energy spectrum on normal cells are not well understood. The current study examined cell survival and DNA damage in normal prostate cells after exposure to out-of-field radiation both with and without the transfer of bystander factors. The effect of a change in energy spectrum out-of-field compared to in-field was also investigated. Prostate cancer (LNCaP) and normal prostate (PNT1A) cells were placed in-field and out-of-field, respectively, with the PNT1A cells being located 1 cm from the field edge when in-field cells were being irradiated with 2 Gy. Clonogenic and γ-H2AX assays were performed postirradiation to examine cell survival and DNA damage. The assays were repeated when bystander factors from the LNCaP cells were transferred to the PNT1A cells and also when the PNT1A cells were irradiated in-field to a different energy spectrum. An average out-of-field dose of 10.8 ± 4.2 cGy produced a significant reduction in colony volume and increase in the number of γ-H2AX foci\\/cell in the PNT1A cells compared to the sham-irradiated control cells. An adaptive response was observed in the PNT1A cells having first received a low out-of-field dose and then the bystander factors. The PNT1A cells showed a significant

  8. Teradiode's high brightness semiconductor lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

    2016-03-01

    TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

  9. Waveguide evanescent field fluorescence microscopy & its application in cell biology

    Science.gov (United States)

    Hassanzadeh, Abdollah

    There are many powerful microscopy technologies available for the investigation of bulk materials as well as for thin film samples. Nevertheless, for imaging an interface, especially live cells on a substrate and ultra thin-films, only Total Internal Reflection Fluorescence (TIRF) microscopy is available. This TIRF microscopy allows imaging without interference of the bulk. Various approaches are employed in fluorescence microscopy applications to restrict the excitation and detection of fluorophores to a thin region of the specimen. Elimination of background fluorescence from outside the focal plane can dramatically improve the signal-to-noise ratio, and consequently, the spatial resolution of the features or events of interest. TIRF microscopy is an evanescent field based microscopy. In this method, fluorescent dyes are only excited within an evanescent field: roughly within 100 nm above a glass coverslip. This will allow imaging surface and interfacial issues of the glass coverslip and an adjacent material. Waveguide evanescent field fluorescence (WEFF) microscopy is a new development for imaging cell-substrate interactions in real time and in vitro. It is an alternative to TIRF microscopy. In this method the light is coupled into a waveguide via an optical grating. The coupled light propagates as a waveguide mode and exhibits an evanescent field on top of the waveguide. This can be used as a surface-bound illumination source to excite fluorophores. This evanescent field serves as an extremely powerful tool for quality control of thin films, to study cell-substrate contacts, and investigating the effect of external agents and drugs on the cell-substrate interaction in real time and in vitro. This new method has been established and optimized to minimize non-uniformity, scattering and photo bleaching issues. Visualizing and quantifying of the cell-substrates and solid thin films have been carried out by WEFF microscopy. The images of the cell-substrate interface

  10. Are solar brightness variations faculae- or spot-dominated?

    CERN Document Server

    Shapiro, A I; Krivova, N A; Yeo, K L; Schmutz, W K

    2016-01-01

    Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations on timescales greater than a day being attributed to surface magnetic field. Independently, ground-based and spaceborne measurements suggest that Sun-like stars show a similar, but significantly broader pattern of photometric variability. To understand whether the broader pattern of stellar variations is consistent with the solar paradigm we assess relative contributions of faculae and spots to solar magnetically-driven brightness variability. We investigate how the solar brightness variability as well as its facular and spot contributions depend on the wavelength, timescale of variability, and position of the observer relative to the ecliptic plane. We perform calculations with the SATIRE model, which returns solar brightness with daily cadence from solar disc area coverages of various magnetic features. Moving the observer away from the ecliptic plane increases the amplitude of 11-year variability a...

  11. The EUVE bright source list

    Science.gov (United States)

    Stroozas, B.; Mcdonald, K.; Antia, B.; Mcdonald, J.; Wiercigroch, A.

    1993-01-01

    Initial results for bright extreme ultraviolet sources discovered during the EUVE all-sky and deep ecliptic surveys have been published as a Bright Source List (BSL) and released to the astronomical community with a recent NASA research announcement (NRA 93-OSS-02, Appendix F). This paper describes the data processing software, the EUVE survey data set, and the production of the BSL at the Center for EUV Astrophysics. The contents, format, and selection criteria for sources, the data processing strategy, some problems encountered, and a summary of the BSL results are presented.

  12. All things bright and beautiful

    OpenAIRE

    Brown, Chloe

    2012-01-01

    'All Things Bright and Beautiful' was exhibited in 20/21 Visual Arts Centre, Scunthorpe, which is sited in a 'redundant' church. The fundamental question that the exhibition explored concerned the role of 'the animal' within contemporary art and within secular society, which in turn hoped to prompt reflections on our understanding of the place of 'the human' in the world and in nature. If there is no divine order, as posited by the hymn 'All Things Bright and Beautiful', where does this leave...

  13. Conversion of bright magneto-optical resonances into dark at fixed laser frequency for D2 excitation of atomic rubidium

    CERN Document Server

    Auzinsh, Marcis; Ferber, Ruvin; Gahbauer, Florian; Kalvans, Linards; Mozers, Arturs; Opalevs, Dmitrijs

    2011-01-01

    Nonlinear magneto-optical resonances on the hyperfine transitions belonging to the D2 line of rubidium were changed from bright to dark resonances by changing the laser power density of the single exciting laser field or by changing the vapor temperature in the cell. In one set of experiments atoms were excited by linearly polarized light from an extended cavity diode laser with polarization vector perpendicular to the light's propagation direction and magnetic field, and laser induced fluorescence (LIF) was observed along the direction of the magnetic field, which was scanned. A low-contrast bright resonance was observed at low laser power densities when the laser was tuned to the Fg=2 --> Fe=3 transition of Rb-87 and near to the Fg=3 --> Fe=4 transition of Rb-85. The bright resonance became dark as the laser power density was increased above 0.6mW/cm2 or 0.8 mW/cm2, respectively. When the Fg=2 --> Fe=3 transition of Rb-87 was excited with circularly polarized light in a second set of experiments, a bright r...

  14. Endothelial cells regulate neural crest and second heart field morphogenesis

    Directory of Open Access Journals (Sweden)

    Michal Milgrom-Hoffman

    2014-07-01

    Full Text Available Cardiac and craniofacial developmental programs are intricately linked during early embryogenesis, which is also reflected by a high frequency of birth defects affecting both regions. The molecular nature of the crosstalk between mesoderm and neural crest progenitors and the involvement of endothelial cells within the cardio–craniofacial field are largely unclear. Here we show in the mouse that genetic ablation of vascular endothelial growth factor receptor 2 (Flk1 in the mesoderm results in early embryonic lethality, severe deformation of the cardio–craniofacial field, lack of endothelial cells and a poorly formed vascular system. We provide evidence that endothelial cells are required for migration and survival of cranial neural crest cells and consequently for the deployment of second heart field progenitors into the cardiac outflow tract. Insights into the molecular mechanisms reveal marked reduction in Transforming growth factor beta 1 (Tgfb1 along with changes in the extracellular matrix (ECM composition. Our collective findings in both mouse and avian models suggest that endothelial cells coordinate cardio–craniofacial morphogenesis, in part via a conserved signaling circuit regulating ECM remodeling by Tgfb1.

  15. High-brightness ultra-cold metastable neon-beam

    CERN Document Server

    Shimizu, Fujio

    2015-01-01

    This paper presents detailed characteristics of an ultra-cold bright metastable neon atomic beam which we have been using for atom-interferometric applications. The basis of the device is an atomic beam released from a magneto-optical trap (MOT) which is operated with a high intensity trapping laser, high magnetic quadrupole field, and large laser detuining. Mainly due to the complex structure of three dimensional magnetic field and laser beams, a bright small spot of atoms is formed near the center of the quadrupole magnetic field under an appropriate operating condition. We obtained the minimum trap diameter of 50 micron meter, the atomic density nearly 10^{13}cm^{-3}, and the atomic temperature slightly less than the Doppler limited temperature of 200 micro-K. By releasing trapped atoms we obtained an bright cold atomic beam which is not far from the collision limited atomic density.

  16. The input-output transformation of the hippocampal granule cells: from grid cells to place fields

    OpenAIRE

    de Almeida, Licurgo; Idiart, Marco; Lisman, John E.

    2009-01-01

    Grid cells in the rat medial entorhinal cortex fire (periodically) over the entire environment. These cells provide input to hippocampal granule cells whose output is characterized by one or more small place fields. We sought to understand how this input-output transformation occurs. Available information allows simulation of this process with no freely adjustable parameters. We first examined the spatial distribution of excitation in granule cells produced by the convergence of excitatory in...

  17. Bright Transients discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-08-01

    Six bright transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  18. Manipulation of red blood cells with electric field

    Science.gov (United States)

    Saboonchi, Hossain; Esmaeeli, Asghar

    2009-11-01

    Manipulation of bioparticles and macromolecules is the central task in many biological and biotechnological processes. The current methods for physical manipulation takes advantage of different forces such as acoustic, centrifugal, magnetic, electromagnetic, and electric forces, as well as using optical tweezers or filtration. Among all these methods, however, the electrical forces are particularly attractive because of their favorable scale up with the system size which makes them well-suited for miniaturization. Currently the electric field is used for transportation, poration, fusion, rotation, and separation of biological cells. The aim of the current research is to gain fundamental understanding of the effect of electric field on the human red blood cells (RBCs) using direct numerical simulation. A front tracking/finite difference technique is used to solve the fluid flow and electric field equations, where the fluid in the cell and the blood (plasma) is modeled as Newtonian and incompressible, and the interface separating the two is treated as an elastic membrane. The behavior of RBCs is investigated as a function of the controlling parameters of the problem such as the strength of the electric field.

  19. Nanosecond pulsed electric fields and the cell cycle

    Science.gov (United States)

    Mahlke, Megan A.

    Exposure to nanosecond pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. The phase of the cell cycle at the time of exposure is linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Additionally, nsPEFs are capable of activating cell cycle checkpoints, which could lead to apoptosis or slow population growth. NsPEFs are emerging as a method for treating tumors via apoptotic induction; therefore, investigating the relevance of nsPEFs and the cell cycle could translate into improved efficacy in tumor treatment. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate the role of cell cycle phase in survival of nsPEFs. CHO populations appeared similar to sham populations post-nsPEFs but exhibited arrest in the G1 phase at 6h after exposure. Jurkat cells exhibited increased cell death after nsPEFs compared to CHO cells but did not exhibit checkpoint arrest at any observed time point. The G1/S phase checkpoint is partially controlled by the action of p53; the lack of an active p53 response in Jurkat cells could contribute to their ability to pass this checkpoint and resist cell cycle arrest. Both cell lines exhibited increased sensitivity to nsPEFs in G2/M phase. Live imaging of CHO cells after nsPEF exposure supports the theory of G1/S phase arrest, as a reduced number of cells undergo mitosis within 24 h when

  20. High gradient magnetic field microstructures for magnetophoretic cell separation.

    Science.gov (United States)

    Abdel Fattah, Abdel Rahman; Ghosh, Suvojit; Puri, Ishwar K

    2016-08-01

    Microfluidics has advanced magnetic blood fractionation by making integrated miniature devices possible. A ferromagnetic microstructure array that is integrated with a microfluidic channel rearranges an applied magnetic field to create a high gradient magnetic field (HGMF). By leveraging the differential magnetic susceptibilities of cell types contained in a host medium, such as paramagnetic red blood cells (RBCs) and diamagnetic white blood cells (WBCs), the resulting HGMF can be used to continuously separate them without attaching additional labels, such as magnetic beads, to them. We describe the effect of these ferromagnetic microstructure geometries have on the blood separation efficacy by numerically simulating the influence of microstructure height and pitch on the HGMF characteristics and resulting RBC separation. Visualizations of RBC trajectories provide insight into how arrays can be optimized to best separate these cells from a host fluid. Periodic microstructures are shown to moderate the applied field due to magnetic interference between the adjacent teeth of an array. Since continuous microstructures do not similarly weaken the resultant HGMF, they facilitate significantly higher RBC separation. Nevertheless, periodic arrays are more appropriate for relatively deep microchannels since, unlike continuous microstructures, their separation effectiveness is independent of depth. The results are relevant to the design of microfluidic devices that leverage HGMFs to fractionate blood by separating RBCs and WBCs. PMID:27294532

  1. Two-dimensional bright and dark-in-bright dipolar Bose–Einstein condensate solitons on a one-dimensional optical lattice

    Science.gov (United States)

    Adhikari, S. K.

    2016-08-01

    We study the statics and dynamics of anisotropic, stable, bright and dark-in-bright dipolar quasi-two-dimensional Bose–Einstein condensate (BEC) solitons on a one-dimensional (1D) optical-lattice (OL) potential. These solitons mobile in a plane perpendicular to a 1D OL trap can have both repulsive and attractive contact interactions. Dark-in-bright solitons are the excited states of bright solitons. The solitons, when subjected to a small perturbation, exhibit sustained breathing oscillation. Dark-in-bright solitons can be created by phase imprinting a bright soliton. At medium velocities the collision between two solitons is found to be quasi-elastic. Results are demonstrated by a numerical simulation of the three-dimensional mean-field Gross–Pitaevskii equation in three spatial dimensions employing realistic interaction parameters for a dipolar 164Dy BEC.

  2. Network Coronal Bright Points: Coronal Heating Concentrations Found in the Solar Magnetic Network

    Science.gov (United States)

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

    1998-01-01

    We examine the magnetic origins of coronal heating in quiet regions by combining SOHO/EIT Fe xii coronal images and Kitt Peak magnetograms. Spatial filtering of the coronal images shows a network of enhanced structures on the scale of the magnetic network in quiet regions. Superposition of the filtered coronal images on maps of the magnetic network extracted from the magnetograms shows that the coronal network does indeed trace and stem from the magnetic network. Network coronal bright points, the brightest features in the network lanes, are found to have a highly significant coincidence with polarity dividing lines (neutral lines) in the network and are often at the feet of enhanced coronal structures that stem from the network and reach out over the cell interiors. These results indicate that, similar to the close linkage of neutral-line core fields with coronal heating in active regions (shown in previous work), low-lying core fields encasing neutral lines in the magnetic network often drive noticeable coronal heating both within themselves (the network coronal bright points) and on more extended field lines rooted around them. This behavior favors the possibility that active core fields in the network are the main drivers of the heating of the bulk of the quiet corona, on scales much larger than the network lanes and cells.

  3. A bright point source of ultrashort hard x-rays from laser bioplasmas

    CERN Document Server

    Krishnamurthy, M; Lad, Amit D; Ahmad, Saima; Narayanan, V; Rajeev, R; Kundu, M; Kumar, G Ravindra; Ray, Krishanu

    2010-01-01

    Micro and nano structures scatter light and amplify local electric fields very effectively. Energy incident as intense ultrashort laser pulses can be converted to x-rays and hot electrons more efficiently with a substrate that suitably modifies the local fields. Here we demonstrate that coating a plain glass surface with a few micron thick layer of an ubiquitous microbe, {\\it Escherichia coli}, catapults the brightness of hard x-ray bremsstrahlung emission (up to 300 keV) by more than two orders of magnitude at an incident laser intensity of 10$^{16}$ W cm$^{-2}$. This increased yield is attributed to the local enhancement of electric fields around individual {\\it E. coli} cells and is reproduced by detailed particle-in-cell (PIC) simulations. This combination of laser plasmas and biological targets can lead to turnkey, multi-kilohertz and environmentally safe sources of hard x-rays.

  4. Verification of wind fields by means of rain cell tracking

    Science.gov (United States)

    Herbort, F.

    2009-09-01

    VERIFICATION OF WIND FIELDS BY MEANS OF RAIN CELL TRACKING Herbort, F., Knigge, C. and Etling, D, Institute of Meteorology and Climatology, Leibniz University Hannover,Germany herbort@muk.uni-hannover.de The regional weather forecast model COSMO-DE of the German weather service is run at a spatial resolution of 2.8 km. This results in rather detailed simulations of meteorological fields like pressure, temperature and wind. In contrast, for verification of those NWP products outside the atmospheric surface layer, only a few radiosonde stations can provide the necessary observations. In order to improve the spatial and temporal resolution of observed wind fields we propose a new method based on the motion of rain cells as observed by the German rain radar network. The radar product consist of the radar reflectivity over Germany caused by hydrometeors with a spatial resolution of about 1 km and a temporal resolution of 5 minutes. The tracking of localised radar echoes caused by post frontal showers has been used for statistical analysis of rain showers in earlier work at our institute (Weusthoff and Hauf,2008). The fields of radar reflectivity are analysed in our work by the so-called PIV (Particle Image Velocimetry) method as used in experimental fluid mechanics for obtaining velocity fields of flow phenomena. Instead of solid particles as used as tracking objects in laboratory flows we use the localised radar reflectivities caused by the rain showers as tracer particles for the PIV method. The PIV algorithm provides two dimensional wind fields in the area of Germany with a few kilometres spatial resolution. The observed wind fields are compared to the wind fields obtained by the COSMO-DE model at several vertical levels in the lowest 4 kilometres of the atmosphere. By this way we could not only obtain some estimates for the skill of the wind field forecasts of the model but also could provide information on the most suitable model level for wind forecast

  5. On-site cell field test support program

    Science.gov (United States)

    Staniunas, J. W.; Merten, G. P.

    1982-09-01

    Utility sites for data monitoring were reviewed and selected. Each of these sites will be instrumented and its energy requirements monitored and analyzed for one year prior to the selection of 40 Kilowatt fuel cell field test sites. Analyses in support of the selection of sites for instrumentation shows that many building sectors offered considerable market potential. These sectors include nursing home, health club, restaurant, industrial, hotel/motel and apartment.

  6. GPM Intercalibrated Radiometer Brightness Temperatures

    Science.gov (United States)

    Stocker, Erich Franz; Chou, Joyce

    2013-04-01

    One of the keys to consistent precipitation retrieval from passive microwave radiometer measurements (whether imagers or sounders) is accurate, long-term consistent brightness temperature retrievals. This becomes doubly important when there measurements are taken from radiometers on multiple platforms, from multiple agencies, with many different purposes. The Global Precipitation Measurement (GPM) mission addresses this issue directly with the production of intercalibrated brightness temperatures from all the partner satellites contributing to the GPM mission. These intercalibrated brightness temperatures are given the product designation: 1C within GPM. This paper will describe the GPM approach to intercalibration 1C products. The intercalibration and creation of the products uses a 5-step methodology: comparison of the partner standard products (either Tb or Ta) with the GPM reference standard; determination of adjustments that should be made to each product to create consistent brightness temperatures; re-orbitization of all orbits (in non-realtime) to be in the standard GPM south-south orbit; application of the adjustments to the partner provide 1B(or 1A) products; production of 1C products in HDF5 using a "standard" logical format for any radiometer regardless of its 1B format. This paper describes each of these steps and provides the background for them. It discusses in some detail the current 1C logical format and why this format facilitates use by downstream product algorithms and end-users. Most importantly it provides the analysis approach established by the GPM inter-calibration working group in establishing the adjustments to be made at the 1C level. Finally, using DMSP F16-18, it provides examples of the 1C products and discusses the adjustments that are made.

  7. Bright solitons from defocusing nonlinearities

    OpenAIRE

    Borovkova, Olga V.; Kartashov, Yaroslav; Torner Sabata, Lluís; Malomed, Boris A.

    2011-01-01

    We report that defocusing cubic media with spatially inhomogeneous nonlinearity, whose strength increases rapidly enough toward the periphery, can support stable bright localized modes. Such nonlinearity landscapes give rise to a variety of stable solitons in all three dimensions, including one-dimensional fundamental and multihump states, two-dimensional vortex solitons with arbitrarily high topological charges, and fundamental solitons in three dimensions. Solitons maintain their coherence ...

  8. 小鼠乳腺癌模型中CD4~+CD25~(bright)CCR6~+Treg的检测及其意义%The detection and its significance of CD4~+ CD25~(bright) CCR6~+ Treg regulatory T cells in murine mammary carcinoma model

    Institute of Scientific and Technical Information of China (English)

    徐林; 徐薇; 蒋正刚; 熊思东

    2010-01-01

    为检测CD4~+ CD25~(bright) CCR~(6+) Treg在小鼠乳腺癌实验动物模型中的分布,并探讨其意义.采用FACS检测正常小鼠和4T1荷瘤小鼠中CD4~+ CD25~(bright)Treg的记忆分子CCR6的表达水平,同时检测CD4~+ CD25~(bright)Treg的CCR6~+和CCR6~-两个亚群的Foxp3表达情况;用增殖抑制实验观察了两个亚群分别对CD4~+CD25 T细胞增殖的抑制作用;用FACS检测CD4~+ CD25~(bright)CCR6~+ Treg在正常小鼠和4T1荷瘤小鼠中PBMC、LN和TIL中的分布情况.结果:4T1荷瘤小鼠中CD4~+ CD25~(bright)Treg的记忆分子CCR6的表达水平较正常小鼠增加;CD4~+ CD25~(bright)Treg的CCR6~+和CCR6~-两个亚群均高表达Foxp3,均能在体外有效抑制CD4~+ CD25 T细胞的增殖;与正常对照相比,CD4~+ CD25~(bright)CCR6~+ Treg在4T1荷瘤模型的引流淋巴结中比例明显增加,并在肿瘤局部存在显著的富集.上述结果提示在肿瘤免疫中存在CD4~+ CD25~(bright)CCR6~+ Treg,其具有效应/记忆样表型,并在肿瘤局部有明显的富集,这可能是肿瘤长期免疫逃逸的重要机制.

  9. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.;

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

  10. Transient expression in tobacco Bright Yellow 2 cells and pollen grains: A fast, efficient and reliable system for functional promoter analysis of plant genes

    Directory of Open Access Journals (Sweden)

    Bratić Ana M.

    2010-01-01

    Full Text Available Gene expression is mediated by DNA sequences directly upstream from the coding sequences, recruited transcription factors and RNA polymerase in a spatially-defined manner. Understanding promoter strength and regulation would enhance our understanding of gene expression. The goal of this study was to develop a fast, efficient and reliable method for testing basal promoter activity and identifying core sequences within its pollen specific elements. In this paper we examined the functionality of buckwheat metallothionein promoter by a histochemical GUS assay in two transient expression systems: BY2 cells and pollen grains. Strong promoter activity was observed in both systems.

  11. Synthesis and Characterization of 8-O-Carboxymethylpyranine (CM-Pyranine as a Bright, Violet-Emitting, Fluid-Phase Fluorescent Marker in Cell Biology.

    Directory of Open Access Journals (Sweden)

    Eric A Legenzov

    Full Text Available To avoid spectral interference with common fluorophores in multicolor fluorescence microscopy, a fluid-phase tracer with excitation and emission in the violet end of the visible spectrum is desirable. CM-pyranine is easily synthesized and purified. Its excitation and emission maxima at 401.5 nm and 428.5 nm, respectively, are well suited for excitation by 405-nm diode lasers now commonly available on laser-scanning microscopes. High fluorescence quantum efficiency (Q = 0.96 and strong light absorption (ε405 > 25,000 M-1cm-1 together make CM-pyranine the brightest violet aqueous tracer. The fluorescence spectrum of CM-pyranine is invariant above pH 4, which makes it a good fluid-phase marker in all cellular compartments. CM-pyranine is very photostable, is retained for long periods by cells, does not self-quench, and has negligible excimer emission. The sum of its properties make CM-pyranine an ideal fluorescent tracer. The use of CM-pyranine as a fluid-phase marker is demonstrated by multicolor confocal microscopy of cells that are also labeled with lipid and nuclear markers that have green and red fluorescence emission, respectively.

  12. Origin of first cells at terrestrial, anoxic geothermal fields.

    Science.gov (United States)

    Mulkidjanian, Armen Y; Bychkov, Andrew Yu; Dibrova, Daria V; Galperin, Michael Y; Koonin, Eugene V

    2012-04-01

    All cells contain much more potassium, phosphate, and transition metals than modern (or reconstructed primeval) oceans, lakes, or rivers. Cells maintain ion gradients by using sophisticated, energy-dependent membrane enzymes (membrane pumps) that are embedded in elaborate ion-tight membranes. The first cells could possess neither ion-tight membranes nor membrane pumps, so the concentrations of small inorganic molecules and ions within protocells and in their environment would equilibrate. Hence, the ion composition of modern cells might reflect the inorganic ion composition of the habitats of protocells. We attempted to reconstruct the "hatcheries" of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells. These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K(+), Zn(2+), Mn(2+), and phosphate. Thus, protocells must have evolved in habitats with a high K(+)/Na(+) ratio and relatively high concentrations of Zn, Mn, and phosphorous compounds. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapor-dominated zones of inland geothermal systems. Under the anoxic, CO(2)-dominated primordial atmosphere, the chemistry of basins at geothermal fields would resemble the internal milieu of modern cells. The precellular stages of evolution might have transpired in shallow ponds of condensed and cooled geothermal vapor that were lined with porous silicate minerals mixed with metal sulfides and enriched in K(+), Zn(2+), and phosphorous compounds.

  13. Electrochemical cells: linking fields and currents with products and reactants

    Science.gov (United States)

    Hutchison, Douglas

    2016-11-01

    The interplay between the electromagnetism and chemistry within an electrochemical cell (a ‘battery’) is modelled in such a way so as to describe both open and closed circuit conditions. It is found that a classical field theory coupled with a generic model of the chemistry can consistently explain the behaviour of the cell and reproduce standard results. But this model also reveals an interesting interplay between time scales (field and chemical) that leads to a capacitive impedance within the cell. The assumption that the stasis associated with the emf results from the inability of ions to overcome the potential barriers near each electrode is abandoned. Rather, the equilibrium is viewed as dynamic and results from a balance between forward and reverse chemical reactions. Ions are able borrow enough energy to overcome the barriers as predicted by quantum theory to fuel the forward reactions. The probability of transmission (i.e. ‘tunnelling’) is calculated using a method based on the energy-time uncertainty principle.

  14. Micro Coronal Bright Points Observed in the Quiet Magnetic Network by SOHO/EIT

    Science.gov (United States)

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

    1997-01-01

    When one looks at SOHO/EIT Fe XII images of quiet regions, one can see the conventional coronal bright points (> 10 arcsec in diameter), but one will also notice many smaller faint enhancements in brightness (Figure 1). Do these micro coronal bright points belong to the same family as the conventional bright points? To investigate this question we compared SOHO/EIT Fe XII images with Kitt Peak magnetograms to determine whether the micro bright points are in the magnetic network and mark magnetic bipoles within the network. To identify the coronal bright points, we applied a picture frame filter to the Fe XII images; this brings out the Fe XII network and bright points (Figure 2) and allows us to study the bright points down to the resolution limit of the SOHO/EIT instrument. This picture frame filter is a square smoothing function (hlargelyalf a network cell wide) with a central square (quarter of a network cell wide) removed so that a bright point's intensity does not effect its own background. This smoothing function is applied to the full disk image. Then we divide the original image by the smoothed image to obtain our filtered image. A bright point is defined as any contiguous set of pixels (including diagonally) which have enhancements of 30% or more above the background; a micro bright point is any bright point 16 pixels or smaller in size. We then analyzed the bright points that were fully within quiet regions (0.6 x 0.6 solar radius) centered on disk center on six different days.

  15. The input-output transformation of the hippocampal granule cells: from grid cells to place fields.

    Science.gov (United States)

    de Almeida, Licurgo; Idiart, Marco; Lisman, John E

    2009-06-10

    Grid cells in the rat medial entorhinal cortex fire (periodically) over the entire environment. These cells provide input to hippocampal granule cells whose output is characterized by one or more small place fields. We sought to understand how this input-output transformation occurs. Available information allows simulation of this process with no freely adjustable parameters. We first examined the spatial distribution of excitation in granule cells produced by the convergence of excitatory inputs from randomly chosen grid cells. Because the resulting summation depends on the number of inputs, it is necessary to use a realistic number (approximately 1200) and to take into consideration their 20-fold variation in strength. The resulting excitation maps have only modest peaks and valleys. To analyze how this excitation interacts with inhibition, we used an E%-max (percentage of maximal suprathreshold excitation) winner-take-all rule that describes how gamma-frequency inhibition affects firing. We found that simulated granule cells have firing maps that have one or more place fields whose size and number approximates those observed experimentally. A substantial fraction of granule cells have no place fields, as observed experimentally. Because the input firing rates and synaptic properties are known, the excitatory charge into granule cells could be calculated (2-3 pC) and was found to be only somewhat larger than required to fire granule cells (1 pC). We conclude that the input-output transformation of dentate granule does not depend strongly on synaptic modification; place field formation can be understood in terms of simple summation of randomly chosen excitatory inputs, in conjunction with a winner-take-all network mechanism.

  16. The dendritic density field of a cortical pyramidal cell

    Directory of Open Access Journals (Sweden)

    Hermann eCuntz

    2012-02-01

    Full Text Available Much is known about the computation in individual neurons in the cortical column. Also, the selective connectivity between many cortical neuron types has been studied in great detail. But due to the complexity of this microcircuitry its functional role within the cortical column remains a mystery. Some of the wiring behavior between neurons can be interpreted directly from their particular dendritic and axonal shapes. Here, I describe the dendritic density field as one key element that remains to be better understood. I sketch an approach to relate dendritic density fields in general to their underlying potential connectivity schemes. As an example, I show how the characteristic shape of a cortical pyramidal cell appears as a direct consequence of connecting inputs arranged in two separate parallel layers.

  17. High brightness beams and applications

    International Nuclear Information System (INIS)

    This paper describes the present research on attaining intense bright electron beams. Thermionic systems are briefly covered. Recent and past results from the photoinjector programs are given. The performance advantages and difficulties presently faced by researchers using photoinjectors is discussed. The progress that has been made in photocathode materials, both in lifetime and quantum efficiency, is covered. Finally, a discussion of emittance measurements of photoinjector systems and how the measurement is complicated by the non-thermal nature of the electron beam is presented

  18. Dose, dose-rate and field size effects on cell survival following exposure to non-uniform radiation fields

    Science.gov (United States)

    Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; McMahon, Stephen J.; O'Sullivan, Joe M.; Schettino, Giuseppe; Hounsell, Alan R.; Prise, Kevin M.

    2012-05-01

    For the delivery of intensity-modulated radiation therapy (IMRT), highly modulated fields are used to achieve dose conformity across a target tumour volume. Recent in vitro evidence has demonstrated significant alterations in cell survival occurring out-of-field which cannot be accounted for on the basis of scattered dose. The radiobiological effect of area, dose and dose-rate on out-of-field cell survival responses following exposure to intensity-modulated radiation fields is presented in this study. Cell survival was determined by clonogenic assay in human prostate cancer (DU-145) and primary fibroblast (AG0-1522) cells following exposure to different modulated field configurations delivered using a X-Rad 225 kVp x-ray source. Uniform survival responses were compared to in- and out-of-field responses in which 25-99% of the cell population was shielded. Dose delivered to the out-of-field region was varied from 1.6-37.2% of that delivered to the in-field region using different levels of brass shielding. Dose rate effects were determined for 0.2-4 Gy min-1 for uniform and modulated exposures with no effect seen in- or out-of-field. Survival responses showed little dependence on dose rate and area in- and out-of-field with a trend towards increased survival with decreased in-field area. Out-of-field survival responses were shown to scale in proportion to dose delivered to the in-field region and also local dose delivered out-of-field. Mathematical modelling of these findings has shown survival response to be highly dependent on dose delivered in- and out-of-field but not on area or dose rate. These data provide further insight into the radiobiological parameters impacting on cell survival following exposure to modulated irradiation fields highlighting the need for refinement of existing radiobiological models to incorporate non-targeted effects and modulated dose distributions.

  19. Entropic and Near-Field Improvements of Thermoradiative Cells

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan K.; Liao, Bolin; Huang, Yi; Boriskina, Svetlana V.; Chen, Gang

    2016-10-01

    A p-n junction maintained at above ambient temperature can work as a heat engine, converting some of the supplied heat into electricity and rejecting entropy by interband emission. Such thermoradiative cells have potential to harvest low-grade heat into electricity. By analyzing the entropy content of different spectral components of thermal radiation, we identify an approach to increase the efficiency of thermoradiative cells via spectrally selecting long-wavelength photons for radiative exchange. Furthermore, we predict that the near-field photon extraction by coupling photons generated from interband electronic transition to phonon polariton modes on the surface of a heat sink can increase the conversion efficiency as well as the power generation density, providing more opportunities to efficiently utilize terrestrial emission for clean energy. An ideal InSb thermoradiative cell can achieve a maximum efficiency and power density up to 20.4% and 327 Wm‑2, respectively, between a hot source at 500 K and a cold sink at 300 K. However, sub-bandgap and non-radiative losses will significantly degrade the cell performance.

  20. Automated Detection and Tracking of Solar Magnetic Bright Points

    CERN Document Server

    Crockett, P J; Mathioudakis, M; Keenan, F P

    2009-01-01

    Magnetic Bright Points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs in the spatial and temporal domains. The algorithm works by mapping the lanes through intensity thresholding. A compass search, combined with a study of the intensity gradient across the detected objects, allows the disentanglement of MBPs from bright pixels within the granules. Object growing is implemented to account for any pixels that might have been removed when mapping the lanes. The images are stabilized by locating long-lived objects that may have been missed due to variable light levels and seeing quality. Tests of the algorithm employing data taken with the Swedish Solar Telescope (SST), reveal that ~90% of MBPs within a 75"x 75" field of view are detected.

  1. High brightness angled cavity quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, D.; Bai, Y.; Bandyopadhyay, N.; Slivken, S.; Razeghi, M., E-mail: razeghi@eecs.northwestern.edu [Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-03-02

    A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm{sup −2 }sr{sup −1} is obtained, which marks the brightest QCL to date.

  2. The Bright New Financial System

    Directory of Open Access Journals (Sweden)

    Associate Professor Adela Coman

    2009-05-01

    Full Text Available By the end of 2008, Mr. Paul Volcker gave financiers a devastating critique. “For all its talented participants, for all its rich rewards” he said, the “bright new financial system” has “failed the test of the marketplace”.In light of the events of recent weeks, it is hard to disagree. A financial system that ends up with the government taking over some of its biggest institutions in serial weekend rescues and which requires the promise of 700 billion dollars in public money to stave off catastrophe is not a trustworthy system. The disappearance of all five big American investment banks – either by bankruptcy or rebirth as commercial banks – is powerful evidence that Wall Street failed “the test of the marketplace”. Something went wrong.But what exactly and why? A more serious analysis needs to distinguish between three separate questions: what is Mr. Volcker’s “bright new financial system”? Second, how far was today’s mess created by instabilities that are inseparable from modern finance and how far was it fuelled by other errors and distortions? Third, to the extent that modern finance does bear the blame, what is the balance between its costs and its benefits and how can it be improved?

  3. The possible origin of facular brightness in the solar atmosphere

    Science.gov (United States)

    Kostik, R.; Khomenko, E.

    2016-05-01

    This paper studies the dependence of the Ca ii H line core brightness on the strength and inclination of the photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the center of the solar disc. We use three simultaneous data sets that were obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of Ba ii 4554 Å line, registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in Fe i 1.56 μm lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in Ca ii H that give information about brightness fluctuations in the chromosphere. The results show that the Ca ii H brightness in the facula strongly depends on the power of waves with periods in the 5-min range, which propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height that is measured from Ba ii line. The Ca ii H brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0°-100°. There is an indirect influence of convective motions on the Ca ii H brightness. The higher the amplitude of convective velocities is and the greater the height is where they change their direction of motion, the brighter the facula. In summary, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also owing to real heating.

  4. Improved Flow-Field Structures for Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gurau, Bogdan

    2013-05-31

    The direct methanol fuel cell (DMFC) is ideal if high energy-density liquid fuels are required. Liquid fuels have advantages over compressed hydrogen including higher energy density and ease of handling. Although state-of-the-art DMFCs exhibit manageable degradation rates, excessive fuel crossover diminishes system energy and power density. Although use of dilute methanol mitigates crossover, the concomitant lowering of the gross fuel energy density (GFED) demands a complex balance-of-plant (BOP) that includes higher flow rates, external exhaust recirculation, etc. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol. NuVant Systems Inc. (NuVant) will maximize the GFED by design and assembly of a DMFC that uses near neat methanol. The approach is to tune the diffusion of highly concentrated methanol (to the anode catalytic layer) to the back-diffusion of water formed at the cathode (i.e. in situ generation of dilute methanol at the anode layer). Crossover will be minimized without compromising the GFED by innovative integration of the anode flow-field and the diffusion layer. The integrated flow-field-diffusion-layers (IFDLs) will widen the current and potential DMFC operating ranges and enable the use of cathodes optimized for hydrogen-air fuel cells.

  5. [Bright light therapy for elderly].

    Science.gov (United States)

    Okawa, Masako

    2015-06-01

    Bright light therapy (BLT) holds considerable promise for sleep problems in the elderly. BLT for community-dwelling patients with Alzheimer's disease showed significant improvement in sleep parameters. In the institutional setting, BLT was effective in reducing daytime nap duration. Morning BLT was found to advance the peak circadian rhythm and increase activity level in daytime and melatonin level at night. Light therapy could be used in combination with other nonpharmacological methods such as social activities, outside walking, physical exercises, which showed greater effects than independent BLT on sleep and cognitive function. BLT treatment strategy was proposed in the present paper. We should pay more attentions to BLT in community setting for mental and physical well-being. PMID:26065132

  6. Enhancing the brightness of high current electron guns

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, W.A.; Birx, D.; Boyd, J.K.; Caporaso, G.; Weir, J.T.

    1985-01-01

    Concepts such as the two-beam accelerator offer the possibility of translating pulsed power technology into a form useful to the design of high luminosity accelerators for high-energy physics applications. Realization of the promise of these concepts will require the design of electron guns which are optimized with respect to beam brightness at current levels of approximately 1 kA. Because high luminosity implies accelerator operation at high repetition rates, the high-current beam source must be designed so that the beam does not intercept the electrodes. In our investigations of electron gun configurations, we have found that the brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. To investigate the sensitivity of beam brightness to these factors in a manner suitable for modelling transient phenomena at the beam head, we have developed a Darwin approximation particle code, DPC. The main component in our experimental program is a readily modified electron gun that allows us to test many candidate cathode materials, types, and electrode geometries at field stresses up to 1 MW/cm. We have also developed several diagnostics suitable for measuring the brightness of intense, low-emittance beams.

  7. Multimillion-cell SAGD models, opportunity for detailed field analysis

    Energy Technology Data Exchange (ETDEWEB)

    Akram, F. [Schlumberger Canada Limited (Canada)

    2011-07-01

    In the heavy oil industry, steam assisted gravity drainage (SAGD) is a new thermal oil recovery process used to enhance oil recovery. However, operators have trouble reaching their objectives. A better understanding of reservoir response is necessary to reach the desired production rates. The aim of this paper is to present a new methodology for carrying out a reservoir simulation study. A multimillion-cell model was developed with realistic properties, structural complexity and heterogeneities; both full field and thermal simulations were conducted. Results showed that the computing technology thus developed offers greater accuracy in less time than is required when using conventional techniques. In addition, this methodology provides a higher degree of confidence in the results by bridging the gap between geology and engineering. The paper is a first step in producing a framework and the methodology presented herein will need to be further tested to confirm its benefits over conventional techniques.

  8. Quantum communication with macroscopically bright nonclassical states.

    Science.gov (United States)

    Usenko, Vladyslav C; Ruppert, Laszlo; Filip, Radim

    2015-11-30

    We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne detection is sensitive to a mode-matching of the bright light to the highly intense local oscillator. Unmatched bright modes of light result in additional noise which technically limits detection of Gaussian entanglement at macroscopic level. When the mode-matching is sufficient, we show that multimode quantum key distribution with bright beams is feasible. It finally merges the quantum communication with classical optical technology of visible beams of light. PMID:26698776

  9. Photometric indicators of visual night sky quality derived from all-sky brightness maps

    Science.gov (United States)

    Duriscoe, Dan M.

    2016-09-01

    Wide angle or fisheye cameras provide a high resolution record of artificial sky glow, which results from the scattering of escaped anthropogenic light by the atmosphere, over the sky vault in the moonless nocturnal environment. Analysis of this record yields important indicators of the extent and severity of light pollution. The following indicators were derived through numerical analysis of all-sky brightness maps: zenithal, average all-sky, median, brightest, and darkest sky brightness. In addition, horizontal and vertical illuminance, resulting from sky brightness were computed. A natural reference condition to which the anthropogenic component may be compared is proposed for each indicator, based upon an iterative analysis of a high resolution natural sky model. All-sky brightness data, calibrated in the V band by photometry of standard stars and converted to luminance, from 406 separate data sets were included in an exploratory analysis. Of these, six locations representing a wide range of severity of impact from artificial sky brightness were selected as examples and examined in detail. All-sky average brightness is the most unbiased indicator of impact to the environment, and is more sensitive and accurate in areas of slight to moderate light pollution impact than zenith brightness. Maximum vertical illuminance provides an excellent indicator of impacts to wilderness character, as does measures of the brightest portions of the sky. Zenith brightness, the workhorse of field campaigns, is compared to the other indicators and found to correlate well with horizontal illuminance, especially at relatively bright sites. The median sky brightness describes a brightness threshold for the upper half of the sky, of importance to telescopic optical astronomy. Numeric indicators, in concert with all-sky brightness maps, provide a complete assessment of visual sky quality at a site.

  10. Look on the Bright Side

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China and Viet Nam downplay maritime disputes and expand economic cooperation China and Viet Nam vowed to streng then maritime cooperation in "less sensitive fields" in disputed waters in the South China Sea. These fields include marine environmental protection, scientific

  11. Static Magnetic Field Attenuates Lipopolysaccharide-Induced Inflammation in Pulp Cells by Affecting Cell Membrane Stability

    Directory of Open Access Journals (Sweden)

    Sung-Chih Hsieh

    2015-01-01

    Full Text Available One of the causes of dental pulpitis is lipopolysaccharide- (LPS- induced inflammatory response. Following pulp tissue inflammation, odontoblasts, dental pulp cells (DPCs, and dental pulp stem cells (DPSCs will activate and repair damaged tissue to maintain homeostasis. However, when LPS infection is too serious, dental repair is impossible and disease may progress to irreversible pulpitis. Therefore, the aim of this study was to examine whether static magnetic field (SMF can attenuate inflammatory response of dental pulp cells challenged with LPS. In methodology, dental pulp cells were isolated from extracted teeth. The population of DPSCs in the cultured DPCs was identified by phenotypes and multilineage differentiation. The effects of 0.4 T SMF on DPCs were observed through MTT assay and fluorescent anisotropy assay. Our results showed that the SMF exposure had no effect on surface markers or multilineage differentiation capability. However, SMF exposure increases cell viability by 15%. In addition, SMF increased cell membrane rigidity which is directly related to higher fluorescent anisotropy. In the LPS-challenged condition, DPCs treated with SMF demonstrated a higher tolerance to LPS-induced inflammatory response when compared to untreated controls. According to these results, we suggest that 0.4 T SMF attenuates LPS-induced inflammatory response to DPCs by changing cell membrane stability.

  12. Bright-Dark Vector Screening-Photovoltaic Spatial Solitons in Biased Photorefractive-Photovoltaic Crystals

    Institute of Scientific and Technical Information of China (English)

    卢克清; 钱士雄; 窦春升; 吴振森

    2002-01-01

    We show that the vector beam evolution equations in properly oriented biased photorefractive-photovoltaic crystals can exhibit bright-dark vector solitons, which result from both the bulk photovoltaic effect and the spatially non-uniform screening of the external bias field. By adjusting the polarization of the incident beam to obtain the appropriate ratio of two orthogonal components, these vector solitons can be established. When the bulk photovoltaic effect is negligible, these vector solitons are bright-dark vector screening solitons. When the external field is absent, these vector solitons predict bright-dark vector photovoltaic solitons.

  13. Soliton fay identities: II. Bright soliton case

    International Nuclear Information System (INIS)

    We present a set of bilinear matrix identities that generalize the ones that have been used to construct the bright soliton solutions for various models. As an example of an application of these identities, we present a simple derivation of the N-bright soliton solutions for the Ablowitz–Ladik hierarchy. (paper)

  14. SURFACE PHOTOMETRY OF LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    DEBLOK, WJG; VANDERHULST, JM; BOTHUN, GD

    1995-01-01

    Low surface brightness (LSB) galaxies are galaxies dominated by an exponential disc whose central surface brightness is much fainter than the value of mu(B)(0) = 21.65 +/- 0.30 mag arcsec(-2) found by Freeman. In this paper we present broadband photometry of a sample of 21 late-type LSB galaxies. Th

  15. Brightness and darkness as perceptual dimensions

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2007-01-01

    A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D) space varying from bright to dark. The

  16. Incoherently coupled dark-bright photorefractive solitons

    Science.gov (United States)

    Chen, Zhigang; Segev, Mordechai; Coskun, Tamer H.; Christodoulides, Demetrios N.; Kivshar, Yuri S.; Afanasjev, Vsevolod V.

    1996-11-01

    We report the observation of incoherently coupled dark-bright spatial soliton pairs in a biased bulk photorefractive crystal. When such a pair is decoupled, the dark component evolves into a triplet structure, whereas the bright one decays into a self-defocusing beam.

  17. Brightness Alteration with Interweaving Contours

    Directory of Open Access Journals (Sweden)

    Sergio Roncato

    2012-12-01

    Full Text Available Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation or when lines of different colours are collinear (neon effect or adjacent (watercolour to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread. The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975 and Kanizsa (1979 in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed.

  18. Correlation between dielectric property by dielectrophoretic levitation and growth activity of cells exposed to electric field.

    Science.gov (United States)

    Hakoda, Masaru; Hirota, Yusuke

    2013-09-01

    The purpose of this study is to develop a system analyzing cell activity by the dielectrophoresis method. Our previous studies revealed a correlation between the growth activity and dielectric property (Re[K(ω)]) of mouse hybridoma 3-2H3 cells using dielectrophoretic levitation. Furthermore, it was clarified that the differentiation activity of many stem cells could be evaluated by the Re[K(ω)] without differentiation induction. In this paper, 3-2H3 cells exposed to an alternating current (AC) electric field or a direct current (DC) electric field were cultivated, and the influence of damage by the electric field on the growth activity of the cells was examined. To evaluate the activity of the cells by measuring the Re[K(ω)], the correlation between the growth activity and the Re[K(ω)] of the cells exposed to the electric field was examined. The relations between the cell viability, growth activity, and Re[K(ω)] in the cells exposed to the AC electric field were obtained. The growth activity of the cells exposed to the AC electric field could be evaluated by the Re[K(ω)]. Furthermore, it was found that the adverse effects of the electric field on the cell viability and the growth activity were smaller in the AC electric field than the DC electric field.

  19. Variations in the Fe mineralogy of bright Martian soil

    Science.gov (United States)

    Murchie, Scott; Mustard, John; Erard, Stephane; Geissler, Paul; Singer, Robert

    1993-01-01

    Bright regions on Mars are interpreted as 'soil' derived by chemical alteration of crustal rocks, whose main pigmentary component is ferric oxide or oxyhydroxide. The mineralogy and mineralogic variability of ferric iron are important evidence for the evolution of Martian soil: mineralogy of ferric phases is sensitive to chemical conditions in their genetic environments, and the spatial distributions of different ferric phases would record a history of both chemical environments and physical mixing. Reflectance spectroscopic studies provide several types of evidence that discriminate possible pigmentary phases, including the position of a crystal field absorption near 0.9 microns and position and strengths of absorptions in the UV-visible wavelength region. Recent telescopic spectra and laboratory measurements of Mars soil analogs suggest that spectral features of bright soil can be explained based on a single pigmentary phase, hematite (alpha-Fe2O3), occurring in both 'nanophase' and more crystalline forms. Here we report on a systematic investigation of Martian bright regions using ISM imaging spectrometer data, in which we examined spatial variations in the position and shape of the approximately 0.9 microns absorption. We found both local and regional heterogeneities that indicate differences in Fe mineralogy. These results demonstrate that bright soils do not represent a single lithology that has been homogenized by eolian mixing, and suggest that weathering of soils in different geologic settings has followed different physical and chemical pathways.

  20. Wide Field-of-View Fluorescence Imaging with Optical-Quality Curved Microfluidic Chamber for Absolute Cell Counting

    Directory of Open Access Journals (Sweden)

    Mohiuddin Khan Shourav

    2016-07-01

    Full Text Available Field curvature and other aberrations are encountered inevitably when designing a compact fluorescence imaging system with a simple lens. Although multiple lens elements can be used to correct most such aberrations, doing so increases system cost and complexity. Herein, we propose a wide field-of-view (FOV fluorescence imaging method with an unconventional optical-quality curved sample chamber that corrects the field curvature caused by a simple lens. Our optics simulations and proof-of-concept experiments demonstrate that a curved substrate with lens-dependent curvature can reduce greatly the distortion in an image taken with a conventional planar detector. Following the validation study, we designed a curved sample chamber that can contain a known amount of sample volume and fabricated it at reasonable cost using plastic injection molding. At a magnification factor of approximately 0.6, the curved chamber provides a clear view of approximately 119 mm2, which is approximately two times larger than the aberration-free area of a planar chamber. Remarkably, a fluorescence image of microbeads in the curved chamber exhibits almost uniform intensity over the entire field even with a simple lens imaging system, whereas the distorted boundary region has much lower brightness than the central area in the planar chamber. The absolute count of white blood cells stained with a fluorescence dye was in good agreement with that obtained by a commercially available conventional microscopy system. Hence, a wide FOV imaging system with the proposed curved sample chamber would enable us to acquire an undistorted image of a large sample volume without requiring a time-consuming scanning process in point-of-care diagnostic applications.

  1. Responses of human normal osteoblast cells and osteoblast-like cell line, MG-63 cells, to pulse electromagnetic field (PEMF

    Directory of Open Access Journals (Sweden)

    Suttatip Kamolmatyakul

    2008-01-01

    Full Text Available The objective of this in vitro study is to investigate the effect of pulsed electromagnetic field (PEMF on cellular proliferation and osteocalcin production of osteoblast-like cell line, MG-63 cells, and human normal osteoblast cells (NHOC obtained from surgical bone specimens. The cells were placed in 24-well culture plates in the amount of 3x104 cell/wells with 2 ml αMEM media supplemented with 10% FBS. The experimental plates were placed between a pair of Helmoltz coils powered by a pulse generator (PEMF, 50 Hz, 1.5 mV/cm in the upper compartment of a dual incubator (Forma. The control plates were placed in the lower compartment of the incubator without Helmotz coils. After three days, the cell proliferation was measured by the method modified from Mossman (J. Immunol Methods 1983; 65: 55-63. Other sets of plates were used for osteocalcin production assessment. Media from these sets were collected after 6 days and assessed for osteocalcin production using ELISA kits. The data were analyzed using a one-way analysis of variance (ANOVA. The results showed that MG-63 cells from the experimental group proliferated significantly more than those from the control group (20% increase, p<0.05. No significant difference in osteocalcin production was detected between the two groups. On the other hand, NHOC from the experimental group produced larger amount of osteocalcin (25% increase, p<0.05 and proliferated significantly more than those from the control group (100% increase, p<0.05. In conclusion, PEMF effect on osteoblasts might depend on their cell type of origin. For osteoblast-like cell line, MG-63 cells, PEMF increased proliferation rate but not osteocalcin production of the cells. However, PEMF stimulation effect on human normal osteoblast cells was most likely associated with enhancement of both osteocalcin production and cell proliferation.

  2. High-brightness switchable multiwavelength remote laser in air

    Energy Technology Data Exchange (ETDEWEB)

    Yao Jinping; Cheng Ya; Xu Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Zeng Bin; Li Guihua; Chu Wei; Ni Jielei; Zhang Haisu [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100080 (China); Xu Huailiang [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Chin, See Leang [Center for Optics, Universite Laval, Quebec City, Quebec G1V 0A6 (Canada)

    2011-11-15

    We demonstrate a harmonic-seeded switchable multiwavelength laser in air driven by intense midinfrared femtosecond laser pulses, in which population inversion occurs at an ultrafast time scale (i.e., less than {approx}200 fs) owing to direct formation of excited molecular nitrogen ions by strong-field ionization of inner-valence electrons. The bright multiwavelength laser in air opens the perspective for remote detection of multiple pollutants based on nonlinear optical spectroscopy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, N.; Santhana Raman, P. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Xu, X.; Pang, R.; Kan, J. A. van, E-mail: phyjavk@nus.edu.sg [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Khursheed, A. [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore)

    2016-02-15

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

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

    International Nuclear Information System (INIS)

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

  5. Experimental studies on ultralow frequency pulsed gradient magnetic field inducing apoptosis of cancer cell and inhibiting growth of cancer cell

    Institute of Scientific and Technical Information of China (English)

    曾繁清; 郑从义; 张新晨; 李宗山; 李朝阳; 王川婴; 张新松; 黄晓玲; 张沪生

    2002-01-01

    The morphology characteristics of cell apoptosis of the malignant tumour cells in magnetic field-treated mouse was observed for the first time. The apoptotic cancer cell contracted, became rounder and divorced from adjacent cells; the heterochromatin condensed and coagulated together along the inner side of the nuclear membrane; the endoplasmic reticulums(ER) expanded and fused with the cellular membrane; many apoptotic bodies which were packed by the cellular membrane appeared and were devoured by some lymphocytes and plasma. Apoptosis of cancer cells was detected by terminal deoxynucleotidyl transferase mediated in situ nick end labeling(TUNEL). It was found that the number of apoptosis cancer cells of the sample treated by the magnetic field is more than that of the control sample. The growth of malignant tumour in mice was inhibited and the ability of immune cell to dissolve cancer cells was improved by ultralow frequency(ULF) pulsed gradient magnetic field; the nuclei DNA contents decreased, indicating that magnetic field can block DNA replication and inhibit mitosis of cancer cells. It was suggested that magnetic field could inhibit the metabolism of cancer cell, lower its malignancy, and restrain its rapid and heteromorphic growth. Since ULF pulsed gradient magnetic field can induce apoptosis of cancer cells and inhibit the growth of malignant tumour, it could be used as a new method to treat cancer.

  6. Bright Sparks of Our Future!

    Science.gov (United States)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  7. Designers predict a bright future

    International Nuclear Information System (INIS)

    As power plant designers and builders, there is a bright future for the industry. The demand for electricity will continue to grow, and the need for new plants will increase accordingly. But companies that develop and supply these plants must adapt to new ways of doing business if they expect to see the dawn of this new age. Several factors will have a profound effect on the generation and use of electricity in future years. Instant communications now reach all corners of the globe, making people everywhere aspire to a higher standard of living. The economic surge needed to satisfy these appetites will, in turn, be fed by a network of suppliers who are themselves restructuring to serve global markets, unimpeded by past nationalistic barriers to trade. The strong correlation between economic progress and the growing demand for electricity is well recognized. A ready supply of affordable electricity is a necessary underpinning for any economic expansion. As economies advance and jobs increase, electric demand grows geometrically, fueled by an ever-improving quality of life. Coupled with increasing demand is the worldwide trend toward privatization of the generation industry. The reasons may vary in different parts of the world, but the effect is the same--companies are battling intensely for the right to build or purchase generating facilities. Those companies, like the industry they serve, are themselves in a period of transition. Once a closed, monopolistic group of owners in a predominantly services-based market, they are, thanks to competitive forces, being driven steadily toward a product-based structure

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

    Science.gov (United States)

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

    2015-12-01

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

  9. Electric field measurement of organic photovoltaic cell model using electrooptic probe

    Science.gov (United States)

    Saito, Ryo; Yabe, Yoko; Suzuki, Akito; Shinagawa, Mitsuru; Sugino, Hiroyuki; Katsuyama, Jun; Matsumoto, Yoshinori

    2016-09-01

    In this paper, we describe the use of a transverse electrooptic probe to measure the electric field of an organic photovoltaic (OPV) cell model. It is necessary to measure the voltage of each OPV cell in order to diagnose failure of the OPV. An electric field is generated by the OPV cell voltage, so measuring the electric field is effective for obtaining a failure diagnosis of the OPV. We use a transverse electrooptic probe as an instrumentation tool for measuring the electric field over the OPV. We confirmed the principle of superposition for the electric field strength from each OPV cell model. These results show that the calibration of each OPV cell voltage can be accomplished by measuring the electric field strength over the OPV cells.

  10. Nanoscale cell membrane organization : a near-field optical view

    NARCIS (Netherlands)

    Koopman, Marjolein

    2006-01-01

    The cell plasma membrane of eukaryotic cells is a lipid bi-layer that separates the cell cytosol from the extracellular environment. The composition and organization of proteins and lipids within this bi-layer have a direct impact on many cellular processes, since they form the senses of the cell. T

  11. Perspectives and controversies in the field of stem cell research.

    Science.gov (United States)

    Romano, Gaetano

    2006-09-01

    The fourth annual meeting of the International Society for Stem Cell Research focused on a number of pressing issues, including: (I) the need to better characterize the biology of stem cells; (II) the need to exploit and optimize the great therapeutic potential of stem cells in tissue regeneration; (III) ethical and safety considerations related to the use of human embryonic stem cells; (IV) the contribution of adult stem cells to carcinogenesis; (V) the need to investigate the biology of cancer stem cells. The purpose of this report is to summarize the current status of stem cell research, as surmised by the proceedings of this meeting.

  12. Can Lucifer Yellow Indicate Correct Permeability of Biological Cell Membrane under An Electric and Magnetic Field?

    Directory of Open Access Journals (Sweden)

    Tahereh Pourmirjafari Firoozabadi

    2015-01-01

    Full Text Available The effect of external magnetic and electric fields, in the range of electroporation and magnetoporation, on Lucifer Yellow (LY fluorescence in the absence of cells is studied. Electric-field-induced quenching and magnetic field-induced increase are observed for fluorescence intensity of LY. Regard to the fact that the variation of field-induced fluorescence, even in the absence of cells, can be observed, the application of LY, as a marker, is debatable in electroporation and magnetoporation techniques.

  13. Antilensing: the bright side of voids.

    Science.gov (United States)

    Bolejko, Krzysztof; Clarkson, Chris; Maartens, Roy; Bacon, David; Meures, Nikolai; Beynon, Emma

    2013-01-11

    More than half of the volume of our Universe is occupied by cosmic voids. The lensing magnification effect from those underdense regions is generally thought to give a small dimming contribution: objects on the far side of a void are supposed to be observed as slightly smaller than if the void were not there, which together with conservation of surface brightness implies net reduction in photons received. This is predicted by the usual weak lensing integral of the density contrast along the line of sight. We show that this standard effect is swamped at low redshifts by a relativistic Doppler term that is typically neglected. Contrary to the usual expectation, objects on the far side of a void are brighter than they would be otherwise. Thus the local dynamics of matter in and near the void is crucial and is only captured by the full relativistic lensing convergence. There are also significant nonlinear corrections to the relativistic linear theory, which we show actually underpredicts the effect. We use exact solutions to estimate that these can be more than 20% for deep voids. This remains an important source of systematic errors for weak lensing density reconstruction in galaxy surveys and for supernovae observations, and may be the cause of the reported extra scatter of field supernovae located on the edge of voids compared to those in clusters. PMID:23383886

  14. The Los Alamos high-brightness photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    O' Shea, P.G.

    1991-01-01

    For a number of years Los Alamos National Laboratory has been developing photocathode RF guns for high-brightness electron beam applications such as free-electron lasers (FELs). Previously thermionic high-voltage guns have been the source of choice for the electron accelerators used to drive FELs. The performance of such FELs is severely limited by the emittance growth produced by the subharmonic bunching process and also by the low peak current of the source. In a photoinjector, a laser driven photocathode is placed directly in a high-gradient RF accelerating cavity. A photocathode allows unsurpassed control over the current, and the spatial and temporal profile of the beam. In addition the electrodeless emission'' avoids many of the difficulties associated with multi-electrode guns, i.e. the electrons are accelerated very rapidly to relativistic energies, and there are no electrodes to distort the accelerating fields. For the past two years we have been integrating a photocathode into our existing FEL facility by replacing our thermionic gun and subharmonic bunchers with a high-gradient 1.3 GHz photoinjector. The photoinjector, which is approximately 0.6 m in length, produces 6 MeV, 300 A, 15 ps linac, and accelerated to a final energy of 40 MeV. We have recently begun lasing at wavelengths near 3 {mu}m. 16 refs., 2 figs., 5 tabs.

  15. Bright boys the making of information technology

    CERN Document Server

    Green, Tom

    2010-01-01

    Everything has a beginning. None was more profound-and quite as unexpected-than Information Technology. Here for the first time is the untold story of how our new age came to be and the bright boys who made it happen. What began on the bare floor of an old laundry building eventually grew to rival in size the Manhattan Project. The unexpected consequence of that journey was huge---what we now know as Information Technology. For sixty years the bright boys have been totally anonymous while their achievements have become a way of life for all of us. "Bright Boys" brings them home. By 1950 they'd

  16. The structure of bright zinc coatings

    Directory of Open Access Journals (Sweden)

    MIODRAG STOJANOVIC

    2000-11-01

    Full Text Available The structures of bright zinc coatings obtained from acid sulfate solutions in the presence of dextrin/salicyl aldehyde mixture were examined. It was shown by the STM technique that the surfaces of bright zinc coatings are covered by hexagonal zinc crystals, the tops of planes of which are flat and mutually parallel and which exhibit smoothness on the atomic level. X-Ray diffraction (XRD analysis of the bright zinc coatings showed that the zinc crystallites are oriented in the (110 plane only.

  17. Cryopreservation of periodontal ligament cells with magnetic field for tooth banking.

    Science.gov (United States)

    Kaku, M; Kamada, H; Kawata, T; Koseki, H; Abedini, S; Kojima, S; Motokawa, M; Fujita, T; Ohtani, J; Tsuka, N; Matsuda, Y; Sunagawa, H; Hernandes, R A M; Ohwada, N; Tanne, K

    2010-08-01

    The purpose of this study was to establish a long-term tooth cryopreservation method that can be used for tooth autotransplantation. Human periodontal ligament (PDL) cells were frozen in 10% dimethyl sulfoxide (Me(2)SO) using a programmed freezer with a magnetic field. Cells were cryopreserved for 7 days at -150 degrees C. Immediately after thawing, the number of surviving cells was counted and the cells were cultured; cultured cells were examined after 48 h. Results indicated that a 0.01 mT of a magnetic field, a 15-min hold-time, and a plunging temperature of -30 degrees C led to the greatest survival rate of PDL cells. Based on these findings, whole teeth were cryopreserved under the same conditions for 1 year. The organ culture revealed that the PDL cells of cryopreserved tooth with a magnetic field could proliferate as much as a fresh tooth, although the cells did not appear in the cryopreserved tooth without a magnetic field. Histological examination and the transmission electron microscopic image of cryopreserved tooth with a magnetic field did not show any destruction of cryopreserved cells. In contrast, severe cell damage was seen in cells frozen without a magnetic field. These results indicated that a magnetic field programmed freezer is available for tooth cryopreservation.

  18. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture

    Science.gov (United States)

    Klein, M.; Pankiewicz, R.; Zalas, M.; Stampor, W.

    2016-07-01

    The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism.

  19. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture

    Science.gov (United States)

    Klein, M.; Pankiewicz, R.; Zalas, M.; Stampor, W.

    2016-01-01

    The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism. PMID:27440452

  20. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture.

    Science.gov (United States)

    Klein, M; Pankiewicz, R; Zalas, M; Stampor, W

    2016-01-01

    The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism. PMID:27440452

  1. Cell Mechanosensitivity: Mechanical Properties and Interaction with Gravitational Field

    Directory of Open Access Journals (Sweden)

    I. V. Ogneva

    2013-01-01

    Full Text Available This paper addressed the possible mechanisms of primary reception of a mechanical stimulus by different cells. Data concerning the stiffness of muscle and nonmuscle cells as measured by atomic force microscopy are provided. The changes in the mechanical properties of cells that occur under changed external mechanical tension are presented, and the initial stages of mechanical signal transduction are considered. The possible mechanism of perception of different external mechanical signals by cells is suggested.

  2. Brightness limitations in multi-kiloampere electron beam sources

    International Nuclear Information System (INIS)

    Heuristic relationships such as the Lawson-Penner criterion, used to scale Free Electron Laser (FEL) amplifier gain and efficiency over orders of magnitude in beam current and brightness, have no fundamental basis. The brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. The design of low emittance, high current electron guns has received considerable attention at Livermore over the past few years. The measured brightnesses of the Experimental Test Accelerator (ETA) and Advanced Test Accelerator (ATA) guns are less than predicted with the EBQ gun design code; this discrepancy is due to plasma effects from the present cold, plasma cathode in the code. The EBQ code is well suited to exploring the current limits of gridless relativistic Pierce columns with moderate current density (2) at the cathode. As EBQ uses a steady-state calculation it is not amenable for study of transient phenomena at the beam head. For this purpose, a Darwin approximation code, DPC, has been written. The main component in our experimental cathode development effort is a readily modified electron gun that will allow us to test many candidate cathode materials, types and electrode geometries at field stresses up to 1 MV/cm. 6 references, 6 figures

  3. The solar brightness temperature at millimeter wavelengths

    Science.gov (United States)

    Kuseski, R. A.; Swanson, P. N.

    1976-01-01

    Measurements of the brightness temperature of the sun near 36 GHz and 93 GHz were made using the new moon as a calibration source. Provided the brightness temperature of the moon is known and all measurements are reduced to the same zenith angle, a simple expression can be used for the sun-to-new moon ratio which is independent of antenna gain, atmospheric absorption and reemission, and radiometer calibration constants. This ratio was measured near 36 GHz and at two frequencies near 93 GHz with a Dicke switched superheterodyne radiometer system and a 2.4 m Cassegrain antenna. The slopes of the solar brightness temperature spectrum based on these ratios were measured. The absolute solar brightness spectrum derived from all current available measurements supplemented by the present ones is also plotted and discussed.

  4. A spectroscopic atlas of bright stars

    CERN Document Server

    Martin, Jack

    2009-01-01

    Suitable for amateur astronomers interested in practical spectroscopy or spectrography, this reference book identifies more than 70 (northern hemisphere) bright stars that are suitable observational targets. It provides finder charts for locating these sometimes-familiar stars.

  5. 高亮度金刚石薄膜场发射荧光管的制作%The Implementation of High Brightness Field Emission Display of Globe-like Diamond Microcrystalline-aggregate Films

    Institute of Scientific and Technical Information of China (English)

    高金海; 李桢; 张武勤; 张兵临

    2013-01-01

    利用微波等离子化学气相沉积法,制备出类球状微米金刚石聚晶薄膜作为场发射阴极材料.通过采用低熔点玻璃粉烧结工艺,从器件封装、器件烧结、器件排气和器件烤消等方面进行了探索和创新,实现了场致发射荧光管的高真空封装.综合采用这套技术,已经研发出的真空场致发射荧光管,在5.45 V/μm电场下,光的亮度达到了11 000 cd/m2.为将来设计制作矩阵寻址场发射平板显示器件奠定了基础.%Field emission display is a new vacuum flat panel display device. The globe-like diamond microcrystalline-aggregates, as a field emission cathode, were fabricated by microwave plasma chemical vapor deposition (MPCVD). Through the use of low temperature melting glass powder sintering process,and innovations in the device package, sintering, consuming such as exhaust and baking exploration, the field emission display of high vacuum package is implemented. Integrated use of this technology has led to a secondary structure, three-pole structure of the field emission display,obtained in 5. 45 V/μm field, and the light intensity of the samples reached 11 000 cd/m2 This consolidates a strong base for the future design of field emission flat panel display of matrix addressing.

  6. A ROSAT Bright Source Catalog Survey with the Swift Satellite

    CERN Document Server

    Fox, D B

    2004-01-01

    We consider the prospects for a complete survey of the 18,811 sources of the ROSAT All-Sky Survey Bright Source Catalog (BSC) with NASA's Swift gamma-ray burst (GRB) mission. By observing each BSC source for 500 s with the satellite's imaging X-ray and UV/optical telescopes, this "Swift Bright (Source) Catalog Survey" (Swift-BCS) would derive ~20 mCrab, 10-100 keV) with the wide-field Burst Alert Telescope (BAT); and a two-year all-sky BAT survey down to >~1 mCrab. The resulting expansion of the catalog of identified X-ray sources from 2000 to 18,000 will provide a greatly-enriched set of targets for observation by XMM-Newton, Chandra, and future high-energy observatories.

  7. Unveiling the nature of bright z ~ 7 galaxies with the Hubble Space Telescope

    CERN Document Server

    Bowler, R A A; McLure, R J; McLeod, D J

    2016-01-01

    We present new Hubble Space Telescope/Wide Field Camera 3 imaging of 25 extremely luminous (-23.2 600A). We find that irregular, multiple-component morphologies suggestive of clumpy or merging systems are common (f_multi > 0.4) in bright z ~ 7 galaxies, and ubiquitous at the very bright end (M_UV 1000 similarly bright galaxies at z ~ 7. Our new HST imaging suggests that the vast majority of these galaxies will be spatially resolved by Euclid, mitigating concerns over dwarf star contamination.

  8. Development of a high brightness ion source

    International Nuclear Information System (INIS)

    The brightness and emittance of an ion beam can depend on the ion temperature, aberrations and scattering, as well as other factors. However, it is the ion temperature which determines the irreducible minimum value of the emittance and hence brightness, as the other components can be eliminated by careful design. An ion source design is presented which has attained this minimum value for the emittance; the dependence of the ion temperature on the plasma source parameters is discussed

  9. Observations and diagnostics in high brightness beams

    Science.gov (United States)

    Cianchi, A.; Anania, M. P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V.

    2016-09-01

    The brightness is a figure of merit largely used in the light sources, like FEL (Free Electron Lasers), but it is also fundamental in several other applications, as for instance Compton backscattering sources, beam driven plasma accelerators and THz sources. Advanced diagnostics are essential tools in the development of high brightness beams. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement.

  10. Brightness/darkness induction and the genesis of a contour

    Science.gov (United States)

    Roncato, Sergio

    2014-01-01

    Visual contours often result from the integration or interpolation of fragmented edges. The strength of the completion increases when the edges share the same contrast polarity (CP). Here we demonstrate that the appearance in the perceptual field of this integrated unit, or contour of invariant CP, is concomitant with a vivid brightness alteration of the surfaces at its opposite sides. To observe this effect requires some stratagems because the formation in the visual field of a contour of invariant CP normally engenders the formation of a second contour and then the rise of two streams of induction signals that interfere in different ways. Particular configurations have been introduced that allow us to observe the induction effects of one contour taken in isolation. I documented these effects by phenomenological observations and psychophysical measurement of the brightness alteration in relation to luminance contrast. When the edges of the same CP complete to form a contour, the background of homogeneous luminance appears to dim at one side and to brighten at the opposite side (in accord with the CP). The strength of the phenomenon is proportional to the local luminance contrast. This effect weakens or nulls when the contour of the invariant CP separates surfaces filled with different gray shades. These conflicting results stimulate a deeper exploration of the induction phenomena and their role in the computation of brightness contrast. An alternative perspective is offered to account for some brightness illusions and their relation to the phenomenal transparency. The main assumption asserts that, when in the same region induction signals of opposite CP overlap, the filling-in is blocked unless the image is stratified into different layers, one for each signal of the same polarity. Phenomenological observations document this “solution” by the visual system. PMID:25368570

  11. Cell ageing: a flourishing field for neurodegenerative diseases

    Directory of Open Access Journals (Sweden)

    Dora Brites

    2015-06-01

    Full Text Available Cellular senescence is viewed as an irreversible cell-cycle arrest mechanism involving a complexity of biological progressive processes and the acquisition of diverse cellular phenotypes. Several cell-intrinsic and extrinsic causes (stresses may lead to diverse cellular signaling cascades that include oxidative stress, mitochondrial dysfunction, DNA damage, excessive accumulation of misfolded proteins, impaired microRNA processing and inflammation. Here we review recent advances in the causes and consequences of brain cell ageing, including the senescence of endothelial cells at the central nervous system barriers, as well as of neurons and glial cells. We address what makes ageing an important risk factor for neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and cerebrovascular disease. In particular, we highlight the importance of defects in mitochondrial dynamics, in the cathepsin activity imbalance, in cell-cell communication, in the accumulation of misfolded and unfolded proteins and in the microRNA profiling as having potential impact on cellular ageing processes. Another important aspect is that the absence of specific senescence biomarkers has hampered the characterization of senescent cells in ageing and age-associated diseases. In accordance, the senescence-associated secretory phenotype (SASP or secretome was shown to vary in distinct cell types and upon different stressors, and SASP heterogeneity is believed to create subsets of senenescent cells. In addition to secreted proteins, we then place extracellular vesicles (exosomes and ectosomes as important mediators of intercellular communication with pathophysiological roles in disease spreading, and as emerging targets for therapeutic intervention. We also discuss the application of engineered extracellular vesicles as vehicles for drug delivery. Finally, we summarize current knowledge on methods to rejuvenate senescent cells

  12. Energy-exchange collisions of dark-bright-bright vector solitons.

    Science.gov (United States)

    Radhakrishnan, R; Manikandan, N; Aravinthan, K

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices. PMID:26764780

  13. Energy-exchange collisions of dark-bright-bright vector solitons

    Science.gov (United States)

    Radhakrishnan, R.; Manikandan, N.; Aravinthan, K.

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.

  14. Numerical simulation of soil brightness temperatures at wavelength of 21 cm

    Science.gov (United States)

    Mo, T.; Schmugge, T. J.

    1981-01-01

    A simulation model is applied to reproduce some observed brightness temperatures at a wavelength of 21 cm. The simulated results calculated with two different soil textures are compared directly with observations measured over fields in Arizona and South Dakota. It is found that good agreement is possible by properly adjusting the surface roughness parameter. Correlation analysis and linear regression of the brightness temperatures versus soil moistures are also carried out.

  15. Origin of first cells at terrestrial, anoxic geothermal fields

    OpenAIRE

    Mulkidjanian, Armen Y; Bychkov, Andrew Yu.; Dibrova, Daria V.; Michael Y. Galperin; Koonin, Eugene V

    2012-01-01

    All cells contain much more potassium, phosphate, and transition metals than modern (or reconstructed primeval) oceans, lakes, or rivers. Cells maintain ion gradients by using sophisticated, energy-dependent membrane enzymes (membrane pumps) that are embedded in elaborate ion-tight membranes. The first cells could possess neither ion-tight membranes nor membrane pumps, so the concentrations of small inorganic molecules and ions within protocells and in their environment would equilibrate. Hen...

  16. Cell Mechanosensitivity: Mechanical Properties and Interaction with Gravitational Field

    OpenAIRE

    I. V. Ogneva

    2013-01-01

    This paper addressed the possible mechanisms of primary reception of a mechanical stimulus by different cells. Data concerning the stiffness of muscle and nonmuscle cells as measured by atomic force microscopy are provided. The changes in the mechanical properties of cells that occur under changed external mechanical tension are presented, and the initial stages of mechanical signal transduction are considered. The possible mechanism of perception of different external mechanical signals by c...

  17. A New Rotation Phenomena of Cells Induced by Homegeneous Electric Field

    Science.gov (United States)

    Hatakeyama, Toyomasa; Yagi, Hiroshi

    1990-05-01

    When at least two plant protoplasts are located close to each other under homogeneous electric field, almost all of the cells rotate in the vicinity of its frequency of 10 kHz and specific cells in the vicinity of 10 MHz. The first rotation occurs in the plane constituted by the connecting line between two cells and the applied electric field line. This angular velocity increases with the square of the field strength. On the other hand, the second rotation or new rotation occurs in any plane and its angular velocity complicatedly depends on the field strength. Furthermore, when two cells are arranged in such a way that their connecting line is parallel to the applied field, the second rotation occurs but the first does not. The distinctive feature of the second rotation can be explained by the anisotropic dielectric in the cell due to the shape of its vacuole.

  18. The influence of magnetic fields exposure on neurite outgrowth in PC12 rat pheochromocytoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Fan, W.; Ding, J. E-mail: masdingj@nus.edu.sg; Duan, W.; Zhu, Y.M

    2004-11-01

    The aim of present work was to investigate the influence of magnetic fields exposure on neurite outgrowth in PC12 cells. The neurite number per cell, length of neurites and directions of neurite growth with respect to the direction of the magnetic field were analyzed after exposure to 50 Hz electromagnetic field for 96 h. A promotion was observed under a weak field (0.23 mT), as the average number of neurites per cell increased to 2.38{+-}0.06 compared to 1.91{+-}0.07 neurites/cell of the control dishes, while inhibition and directional outgrowth was evident under a relatively stronger field (1.32 mT). Our work shows that biological systems can be very sensitive to the strength of electromagnetic field.

  19. External magnetic field effect on bifacial silicon solar cell''s electric power and conversion efficiencyExternal magnetic field effect on bifacial silicon solar cell''s electric power and conversion efficiency

    OpenAIRE

    ZERBO, ISSA; ZOUNGRANA, MARTIAL; SOURABIE, IDRISSA; Ouedraogo, Adama; ZOUMA, BERNARD; BATHIEBO, DIEUDONNE JOSEPH

    2015-01-01

    This article presents a modelling study of external magnetic field effect on a bifacial silicon solar cell's electric power and conversion efficiency. After the resolution of the magnetotransport equation and continuity equation of excess minority carriers, we calculate the photocurrent density and the photovoltage and then we deduce the solar cell's electric power before discussing the influence of the magnetic field on those electrical parameters. Using the electric power curves...

  20. Effects of Pulsed Electromagnetic Field on Differentiation of HUES-17 Human Embryonic Stem Cell Line

    OpenAIRE

    Yi-Lin Wu; Shi-Rong Ma; Tao Peng; Zeng-Hui Teng; Xiang-Yan Liang; Guo-Zhen Guo; Hai-Feng Zhang; Kang-Chu Li

    2014-01-01

    Electromagnetic fields are considered to potentially affect embryonic development, but the mechanism is still unknown. In this study, human embryonic stem cell (hESC) line HUES-17 was applied to explore the mechanism of exposure on embryonic development to pulsed electromagnetic field (PEMF) for 400 pulses at different electric field intensities and the differentiation of HUES-17 cells was observed after PEMF exposure. The expression of alkaline phosphatase (AP), stage-specific embryonic ant...

  1. Magnetic field effects on viscous fingering of a ferrofluid in a radial Hele-Shaw cell

    Energy Technology Data Exchange (ETDEWEB)

    Herreman, Wietze [Laboratoire Louis Neel, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Molho, Pierre [Laboratoire Louis Neel, CNRS, BP 166, 38042 Grenoble Cedex 9 (France)]. E-mail: molho@grenoble.cnrs.fr; Neveu, Sophie [LI2C, Universite Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05 (France)

    2005-03-15

    We have studied the effects of a magnetic field on viscous fingering when a ferrofluid is pushed in a more viscous liquid in a circular Hele-Shaw cell. The main effect of the magnetic field, as already known, is to stabilize interfaces parallel to the field and to destabilize interfaces normal to the field. Depending on the growth regime (quasi static, fingering, dendritic growth), which depends on parameters like the cell thickness and oil viscosity, the combination of field effect and anisotropy is analyzed through the various observed patterns.

  2. Experimental Study and Comparison of Various Designs of Gas Flow Fields to PEM Fuel Cells and Cell Stack Performance

    OpenAIRE

    PeiwenLi

    2014-01-01

    In this study, a significant number of experimental tests to proton exchange membrane (PEM) fuel cells were conducted to investigate the effect of gas flow fields on fuel cell performance. Graphite plates with various flow field or flow channel designs, from literature survey and also novel designs by the authors, were used for the PEM fuel cell assembly. The fabricated fuel cells have an effective membrane area of 23.5 cm2. The results showed that the serpentine flow channel design is still ...

  3. MAGNETIC FLUX SUPPLEMENT TO CORONAL BRIGHT POINTS

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Chaozhou; Huang, Zhenghua; Xia, Lidong; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China); Madjarska, Maria S., E-mail: z.huang@sdu.edu.cn [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)

    2016-02-10

    Coronal bright points (BPs) are associated with magnetic bipolar features (MBFs) and magnetic cancellation. Here we investigate how BP-associated MBFs form and how the consequent magnetic cancellation occurs. We analyze longitudinal magnetograms from the Helioseismic and Magnetic Imager to investigate the photospheric magnetic flux evolution of 70 BPs. From images taken in the 193 Å passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs’ lifetimes vary from 2.7 to 58.8 hr. The formation of the BP MBFs is found to involve three processes, namely, emergence, convergence, and local coalescence of the magnetic fluxes. The formation of an MBF can involve more than one of these processes. Out of the 70 cases, flux emergence is the main process of an MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the flux emergence and the BP appearance in the AIA 193 Å passband varies from 0.1 to 3.2 hr with an average of 1.3 hr. While magnetic cancellation is found in all 70 BPs, it can occur in three different ways: (I) between an MBF and small weak magnetic features (in 33 BPs); (II) within an MBF with the two polarities moving toward each other from a large distance (34 BPs); (III) within an MBF whose two main polarities emerge in the same place simultaneously (3 BPs). While an MBF builds up the skeleton of a BP, we find that the magnetic activities responsible for the BP heating may involve small weak fields.

  4. Dark Skies, Bright Kids! Year 4

    Science.gov (United States)

    Sokal, Kimberly R.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Borish, J.; Crawford, S. B.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Jackson, L.; Liss, S.; Oza, A.; Peacock, S.; Prager, B.; Romero, C.; Sivakoff, G. R.; Walker, L.; Whelan, D. G.; Zucker, C.

    2013-01-01

    Aiming to engage young children's natural excitement and curiosity, the outreach group Dark Skies, Bright Kids (DSBK) brings a hands-on approach to astronomy to elementary schools in Virginia. We hope to enhance children's view and understanding of science while exploring the Universe using fun activities. DSBK focuses on rural and underserved schools in Albemarle County and offers a semester-long astronomy club for third through fifth grade students. We believe regular interactions foster personal relationships between students and volunteers that encourage a life-long interest in science. In our fourth year of hosting clubs, we returned to Ivy Creek Elementary School, where we saw wonderful responses from a special group of students with `low-incidence' disabilities. DSBK has grown to realize a broader reach beyond local astronomy clubs; we hope to ignite a spark of interest in astronomy and science more widely- in more children, their families, and their teachers. We also hosted the Second Annual Central Virginia Star Party with an open invitation to the community to encourage families to enjoy astronomy together. Throughout the year, DSBK now holds 'one-off' programs (akin to astronomy field days) for elementary schools and children's groups throughout Virginia. Furthermore, we are in the final stages of a project to create two bilingual astronomy books called "Snapshots of the Universe", in Spanish and French with English translations. This art book will be made available online and we are working to get a copy in every elementary school in the state. DSBK has begun to reach out to elementary school teachers in order to provide them with useful and engaging classroom material. We have adapted our volunteer-created activities into useful and ready-to-use lessons, available online. After improvements based on research through interactions and feedback from teachers, we have explicitly identified the learning goals in terms of Virginia's Standards of Learning

  5. Modulation of cell function by electric field: a high-resolution analysis.

    Science.gov (United States)

    Taghian, T; Narmoneva, D A; Kogan, A B

    2015-06-01

    Regulation of cell function by a non-thermal, physiological-level electromagnetic field has potential for vascular tissue healing therapies and advancing hybrid bioelectronic technology. We have recently demonstrated that a physiological electric field (EF) applied wirelessly can regulate intracellular signalling and cell function in a frequency-dependent manner. However, the mechanism for such regulation is not well understood. Here, we present a systematic numerical study of a cell-field interaction following cell exposure to the external EF. We use a realistic experimental environment that also recapitulates the absence of a direct electric contact between the field-sourcing electrodes and the cells or the culture medium. We identify characteristic regimes and present their classification with respect to frequency, location, and the electrical properties of the model components. The results show a striking difference in the frequency dependence of EF penetration and cell response between cells suspended in an electrolyte and cells attached to a substrate. The EF structure in the cell is strongly inhomogeneous and is sensitive to the physical properties of the cell and its environment. These findings provide insight into the mechanisms for frequency-dependent cell responses to EF that regulate cell function, which may have important implications for EF-based therapies and biotechnology development. PMID:25994294

  6. BRITE-Constellation: nanosatellites for precision photometry of bright stars

    CERN Document Server

    Weiss, W W; Moffat, A F J; Schwarzenberg-Czerny, A; Koudelka, O F; Grant, C C; Zee, R E; Kuschnig, R; Mochnacki, St; Matthews, J M; Orleanski, P; Pamyatnykh, A; Pigulski, A; Alves, J; Guedel, M; Handler, G; Wade, G A; Zwintz, K; CCD,

    2014-01-01

    BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, the brightness and temperature variations of stars generally brighter than mag(V) ~ 4, with precision and time coverage not possible from the ground. The current mission design consists of six nanosats (hence Constellation): two from Austria, two from Canada, and two from Poland. Each 7 kg nanosat carries an optical telescope of aperture 3 cm feeding an uncooled CCD. One instrument in each pair is equipped with a blue filter, the other with a red filter. Each BRITE instrument has a wide field of view (~24 degrees), so up to about 15 bright stars can be observed simultaneously, sampled in 32 pixel x 32 pixel sub-rasters. Photometry of additional fainter targets, with reduced precision but thorough time sampling, will be possible through onboard data processing. The BRITE sample is dominated by the most intrinsically luminous stars: massive stars seen at all e...

  7. Tumour Cell Membrane Poration and Ablation by Pulsed Low-Intensity Electric Field with Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2015-03-01

    Full Text Available Electroporation is a physical method to increase permeabilization of cell membrane by electrical pulses. Carbon nanotubes (CNTs can potentially act like “lighting rods” or exhibit direct physical force on cell membrane under alternating electromagnetic fields thus reducing the required field strength. A cell poration/ablation system was built for exploring these effects of CNTs in which two-electrode sets were constructed and two perpendicular electric fields could be generated sequentially. By applying this system to breast cancer cells in the presence of multi-walled CNTs (MWCNTs, the effective pulse amplitude was reduced to 50 V/cm (main field/15 V/cm (alignment field at the optimized pulse frequency (5 Hz of 500 pulses. Under these conditions instant cell membrane permeabilization was increased to 38.62%, 2.77-fold higher than that without CNTs. Moreover, we also observed irreversible electroporation occurred under these conditions, such that only 39.23% of the cells were viable 24 h post treatment, in contrast to 87.01% cell viability without presence of CNTs. These results indicate that CNT-enhanced electroporation has the potential for tumour cell ablation by significantly lower electric fields than that in conventional electroporation therapy thus avoiding potential risks associated with the use of high intensity electric pulses.

  8. Variations in Cell Surfaces of Estrogen Treated Breast Cancer Cells Detected by A Combined Instrument for Far-Field and Near-Field Microscopy

    Directory of Open Access Journals (Sweden)

    P. Perner

    2002-01-01

    Full Text Available The response of single breast cancer cells (cell line T‐47D to 17β‐estradiol (E2 under different concentrations was studied by using an instrument that allows to combine far‐field light microscopy with high resolution scanning near‐field (AFM/SNOM microscopy on the same cell. Different concentrations of E2 induce clearly different effects as well on cellular shape (in classical bright‐field imaging as on surface topography (atomic force imaging and absorbance (near‐field light transmission imaging. The differences range from a polygonal shape at zero via a roughly spherical shape at physiological up to a spindle‐like shape at un‐physiologically high concentrations. The surface topography of untreated control cells was found to be regular and smooth with small overall height modulations. At physiological E2 concentrations the surfaces became increasingly jagged as detected by an increase in membrane height. After application of the un‐physiological high E2 concentration the cell surface structures appeared to be smoother again with an irregular fine structure. The general behaviour of dose dependent differences was also found in the near‐field light transmission images. In order to quantify the treatment effects, line scans through the normalised topography images were drawn and a rate of co‐localisation between high topography and high transmission areas was calculated. The cell biological aspects of these observations are, so far, not studied in detail but measurements on single cells offer new perspectives to be empirically used in diagnosis and therapy control of breast cancers.

  9. Vertical electric field stimulated neural cell functionality on porous amorphous carbon electrodes.

    Science.gov (United States)

    Jain, Shilpee; Sharma, Ashutosh; Basu, Bikramjit

    2013-12-01

    We demonstrate the efficacy of amorphous macroporous carbon substrates as electrodes to support neuronal cell proliferation and differentiation in electric field mediated culture conditions. The electric field was applied perpendicular to carbon substrate electrode, while growing mouse neuroblastoma (N2a) cells in vitro. The placement of the second electrode outside of the cell culture medium allows the investigation of cell response to electric field without the concurrent complexities of submerged electrodes such as potentially toxic electrode reactions, electro-kinetic flows and charge transfer (electrical current) in the cell medium. The macroporous carbon electrodes are uniquely characterized by a higher specific charge storage capacity (0.2 mC/cm(2)) and low impedance (3.3 kΩ at 1 kHz). The optimal window of electric field stimulation for better cell viability and neurite outgrowth is established. When a uniform or a gradient electric field was applied perpendicular to the amorphous carbon substrate, it was found that the N2a cell viability and neurite length were higher at low electric field strengths (≤ 2.5 V/cm) compared to that measured without an applied field (0 V/cm). While the cell viability was assessed by two complementary biochemical assays (MTT and LDH), the differentiation was studied by indirect immunostaining. Overall, the results of the present study unambiguously establish the uniform/gradient vertical electric field based culture protocol to either enhance or to restrict neurite outgrowth respectively at lower or higher field strengths, when neuroblastoma cells are cultured on porous glassy carbon electrodes having a desired combination of electrochemical properties.

  10. Observing Faint Companions Close to Bright Stars

    Science.gov (United States)

    Serabyn, Eugene

    2012-04-01

    Progress in a number of technical areas is enabling imaging and interferometric observations at both smaller angular separations from bright stars and at deeper relative contrast levels. Here we discuss recent progress in several ongoing projects at the Jet Propulsion Laboratory. First, extreme adaptive optics wavefront correction has recently enabled the use of very short (i.e., blue) wavelengths to resolve close binaries. Second, phase-based coronagraphy has recently allowed observations of faint companions to within nearly one diffraction beam width of bright stars. Finally, rotating interferometers that can observe inside the diffraction beam of single aperture telescopes are being developed to detect close-in companions and bright exozodiacal dust. This paper presents a very brief summary of the techniques involved, along with some illustrative results.

  11. Increasing the brightness of light sources

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ling

    2006-11-16

    In this work the principle of light recycling is applied to artificial light sources in order to achieve brightness enhancement. Firstly, the feasibilities of increasing the brightness of light sources via light recycling are examined theoretically, based on the fundamental laws of thermodynamics including Kirchhoff's law on radiation, Planck's law, Lambert-Beer's law, the etendue conservation and the brightness theorem. From an experimental viewpoint, the radiation properties of three different kinds of light sources including short-arc lamps, incandescent lamps and LEDs characterized by their light-generating mechanisms are investigated. These three types of sources are used in light recycling experiments, for the purpose of 1. validating the intrinsic light recycling effect in light sources, e. g. the intrinsic light recycling effect in incandescent lamps stemming from the coiled filament structure. 2. acquiring the required parameters for establishing physical models, e.g. the emissivity/absorptivity of the short-arc lamps, the intrinsic reflectivity and the external quantum efficiency of LEDs. 3. laying the foundations for designing optics aimed at brightness enhancement according to the characteristics of the sources and applications. Based on the fundamental laws and experiments, two physical models for simulating the radiance distribution of light sources are established, one for thermal filament lamps, the other for luminescent sources, LEDs. As validation of the theoretical and experimental investigation of the light recycling effect, an optical device, the Carambola, is designed for achieving deterministic and multiple light recycling. The Carambola has the function of a concentrator. In order to achieve the maximum possible brightness enhancement with the Carambola, several combinations of sources and Carambolas are modelled in ray-tracing simulations. Sources with different light-emitting mechanisms and different radiation properties

  12. Biofilm responses to smooth flow fields and chemical gradients in novel microfluidic flow cells

    OpenAIRE

    Song, Jisun L.; Au, Kelly H.; Huynh, Kimberly T.; Packman, Aaron I.

    2013-01-01

    We present two novel microfluidic flow cells developed to provide reliable control of flow distributions and chemical gradients in biofilm studies. We developed a single-inlet microfluidic flow cell to support biofilm growth under a uniform velocity field, and a double-inlet flow cell to provide a very smooth transverse concentration gradient. Both flow cells consist of a layer of polydimethylsiloxane (PDMS) bonded to glass cover slips and were fabricated using the replica molding technique. ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Achilleos, V.; Frantzeskakis, D. J. [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens GR-157 84 (Greece); Kevrekidis, P. G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003-4515 (United States); Rothos, V. M. [Department of Mathematics, Physics Computational Sciences, Faculty of Engineering, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)

    2011-11-15

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

  14. A novel method of evaluating large mode area fiber design by brightness factor

    Institute of Scientific and Technical Information of China (English)

    张海涛; 陈丹; 任海翠; 闫平; 巩马理

    2015-01-01

    A novel evaluation term and a more reasonable criterion which is described by a new parameter of brightness factor for active large mode area fiber design are presented. The brightness factor evaluation method is based on the transverse mode competition mechanism in fiber lasers and amplifiers. Brightness factor can be seen as a description of fiber general property since it can represent the output laser brightness of the fiber laser system and its ability to resist nonlinear effect. A core-doped active large pitch fiber with a core diameter of 190 µm and a mode-field diameter of 180 µm is designed by this method, and the designed fiber allows the effective single-mode operation.

  15. The environment of Low Surface Brightness Galaxies

    OpenAIRE

    Rosenbaum, S. D.; Bomans, D. J.

    2004-01-01

    Using the Early Data Release of the Sloan Digital Sky Survey (SDSS) we investigated the clustering properties of Low Surface Brightness (LSB) galaxies in comparison to normal, High Surface Brightness (HSB) galaxies. We selected LSB galaxies and HSB galaxies with well measured redshifts from the SDSS data base and performed three-dimensional neighbour counting analysis within spheres of radii between 0.8 Mpc and 8.0 Mpc. As a second analysis method we used an N-th neighbour analysis with N var...

  16. The historical investigation of cometary brightness

    Science.gov (United States)

    Hughes, David W.

    1998-12-01

    The interpretation of the way in which the brightness of a comet varied as a function of both its heliocentric and geocentric distance was essentially started by Isaac Newton in his book Philosophiae Naturalis Principia Mathematica, published in 1687. Astronomers have argued about the form of this variability ever since, and for many years it was regarded as an important clue as to the physical nature of the cometary nucleus and its decay process. This paper reviews our understanding of the causes of cometary brightness variability between about 1680 and the 1950s.

  17. Magneto-optical control of bright atomic solitons

    OpenAIRE

    Potting, S.; Zobay, O.; Meystre, P.; Wright, E. M.

    2000-01-01

    In previous work we showed that bright atomic solitons can arise in spinor Bose-Einstein condensates in the form of gap solitons even for repulsive many-body interactions. Here we further explore the properties of atomic gap solitons and show that their internal structure can be used to both excite them and control their center-of-mass motion using applied laser and magnetic fields. As an illustration we demonstrate a nonlinear atom-optical Mach-Zehnder interferometer based on gap solitons.

  18. Continuous variable quantum communication with bright entangled optical beams

    Institute of Scientific and Technical Information of China (English)

    XIE Chang-de; ZHANG Jing; PAN Qing; JIA Xiao-jun; PENG Kun-chi

    2006-01-01

    In this paper,we briefly introduce the basic concepts and protocols of continuous variable quantum communication,and then summarize the experimental researches accomplished by our group in this field.The main features of quantum communication systems used in our experiments are:(1) The bright entangled optical beams with the anticorrelated amplitude quadratures and the correlated phase quadratures that serve as the entanglement resources and (2) The Bell-state direct detection systems are utilized in the measurements of quantum entanglement and transmitted signals instead of the usually balanced homodyne detectors.

  19. Bright perspectives for nuclear photonics

    International Nuclear Information System (INIS)

    With the advent of new high-power, short-pulse laser facilities in combination with novel technologies for the production of highly brilliant, intense γ beams (like, e.g., Extreme Light Infrastructure - Nuclear Physics (ELI-NP) in Bucharest, MEGaRay in Livermore or a planned upgrade of the HIγS facility at Duke University), unprecedented perspectives will open up in the coming years for photonuclear physics both in basic sciences as in various fields of applications. Ultra-high sensitivity will be enabled by an envisaged increase of the γ-beam spectral density from the presently typical 102γ/eVs to about 104γ/eVs, thus enabling a new quality of nuclear photonics, assisted by new γ-optical elements. Photonuclear reactions with highly brilliant γ beams will allow to produce radioisotopes for nuclear medicine with much higher specific activity and/or more economically than with conventional methods. This will open the door for completely new clinical applications of radioisotopes. The isotopic, state-selective sensitivity of the well-established technique of nuclear resonance fluorescence (NRF) will be boosted by the drastically reduced energy bandwidth (<0.1%) of the novel γ beams. Together with a much higher intensity of these beams, this will pave the road towards a γ-beam based non-invasive tomography and microscopy, assisting the management of nuclear materials, such as radioactive waste management, the detection of nuclear fissile material in the recycling process or the detection of clandestine fissile materials. Moreover, also secondary sources like low-energy, pulsed, polarized neutron beams of high intensity and high brilliance or a new type of positron source with significantly increased brilliance, for the first time fully polarized, can be realized and lead to new applications in solid state physics or material sciences. (authors)

  20. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source

    Science.gov (United States)

    Wells, R. P.; Ghiorso, W.; Staples, J.; Huang, T. M.; Sannibale, F.; Kramasz, T. D.

    2016-02-01

    A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

  1. Yeast cells proliferation on various strong static magnetic fields and temperatures

    Science.gov (United States)

    Otabe, E. S.; Kuroki, S.; Nikawa, J.; Matsumoto, Y.; Ooba, T.; Kiso, K.; Hayashi, H.

    2009-03-01

    The effect of strong magnetic fields on activities of yeast cells were investigated. Experimental yeast cells were cultured in 5 ml of YPD(Yeast extract Peptone Dextrose) for the number density of yeast cells of 5.0 ±0.2 x 106/ml with various temperatures and magnetic fields up to 10 T. Since the yeast cells were placed in the center of the superconducting magnet, the effect of magnetic force due to the diamagnetism and magnetic gradient was negligibly small. The yeast suspension was opened to air and cultured in shaking condition. The number of yeast cells in the yeast suspension was counted by a counting plate with an optical microscope, and the time dependence of the number density of yeast cells was measured. The time dependence of the number density of yeast cells, ρ, of initial part is analyzed in terms of Malthus equation as given by ρ = ρo exp(kt), where k is the growth coefficient. It is found that, the growth coefficient under the magnetic field is suppressed compared with the control. The growth coefficient decreasing as increasing magnetic field and is saturated at about 5 T. On the other hand, it is found that the suppression of growth of yeast cells by the magnetic field is diminished at high temperatures.

  2. Yeast cells proliferation on various strong static magnetic fields and temperatures

    International Nuclear Information System (INIS)

    The effect of strong magnetic fields on activities of yeast cells were investigated. Experimental yeast cells were cultured in 5 ml of YPD(Yeast extract Peptone Dextrose) for the number density of yeast cells of 5.0 ±0.2 x 106/ml with various temperatures and magnetic fields up to 10 T. Since the yeast cells were placed in the center of the superconducting magnet, the effect of magnetic force due to the diamagnetism and magnetic gradient was negligibly small. The yeast suspension was opened to air and cultured in shaking condition. The number of yeast cells in the yeast suspension was counted by a counting plate with an optical microscope, and the time dependence of the number density of yeast cells was measured. The time dependence of the number density of yeast cells, ρ, of initial part is analyzed in terms of Malthus equation as given by ρ = ρo exp(kt), where k is the growth coefficient. It is found that, the growth coefficient under the magnetic field is suppressed compared with the control. The growth coefficient decreasing as increasing magnetic field and is saturated at about 5 T. On the other hand, it is found that the suppression of growth of yeast cells by the magnetic field is diminished at high temperatures.

  3. Signal amelioration of electrophoretically deposited whole-cell biosensors using external electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Yoav, Hadar, E-mail: benyoav@post.tau.ac.il [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Amzel, Tal [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Sternheim, Marek [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel); Belkin, Shimshon [Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Rubin, Adi [Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, 69978 (Israel); Shacham-Diamand, Yosi [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Freeman, Amihay [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel)

    2011-11-01

    Highlights: > We present an electrochemical whole-cell biochip that can apply electric fields. > We examine the integration of cells on a biochip using electrophoretic deposition. > The effect of electric fields on the whole-cell biosensor has been demonstrated. > Relatively short DC electric pulse improves the performance of whole-cell biosensors. > Prolonged AC electric fields deteriorated the whole-cell biosensor performance. - Abstract: This paper presents an integrated whole-cell biochip system where functioning cells are deposited on the solid micro-machined surfaces while specially designed indium tin oxide electrodes that can be used to apply controllable electric fields during various stages; for example during cell deposition. The electrodes can be used also for sensing currents associated with the sensing mechanisms of electrochemical whole-cell biosensors. In this work a new approach integrating live bacterial cells on a biochip using electrophoretic deposition is presented. The biomaterial deposition technique was characterized under various driving potentials and chamber configurations. An analytical model of the electrophoretic deposition kinetics was developed and presented here. The deposited biomass included genetically engineered bacterial cells that may respond to toxic material exposure by expressing proteins that react with specific analytes generating electrochemically active byproducts. In this study the effect of external electric fields on the whole-cell biochips has been successfully developed and tested. The research hypothesis was that by applying electric fields on bacterial whole-cells, their permeability to the penetration of external analytes can be increased. This effect was tested and the results are shown here. The effect of prolonged and short external electric fields on the bioelectrochemical signal generated by sessile bacterial whole-cells in response to the presence of toxins was studied. It was demonstrated that relatively

  4. Signal amelioration of electrophoretically deposited whole-cell biosensors using external electric fields

    International Nuclear Information System (INIS)

    Highlights: → We present an electrochemical whole-cell biochip that can apply electric fields. → We examine the integration of cells on a biochip using electrophoretic deposition. → The effect of electric fields on the whole-cell biosensor has been demonstrated. → Relatively short DC electric pulse improves the performance of whole-cell biosensors. → Prolonged AC electric fields deteriorated the whole-cell biosensor performance. - Abstract: This paper presents an integrated whole-cell biochip system where functioning cells are deposited on the solid micro-machined surfaces while specially designed indium tin oxide electrodes that can be used to apply controllable electric fields during various stages; for example during cell deposition. The electrodes can be used also for sensing currents associated with the sensing mechanisms of electrochemical whole-cell biosensors. In this work a new approach integrating live bacterial cells on a biochip using electrophoretic deposition is presented. The biomaterial deposition technique was characterized under various driving potentials and chamber configurations. An analytical model of the electrophoretic deposition kinetics was developed and presented here. The deposited biomass included genetically engineered bacterial cells that may respond to toxic material exposure by expressing proteins that react with specific analytes generating electrochemically active byproducts. In this study the effect of external electric fields on the whole-cell biochips has been successfully developed and tested. The research hypothesis was that by applying electric fields on bacterial whole-cells, their permeability to the penetration of external analytes can be increased. This effect was tested and the results are shown here. The effect of prolonged and short external electric fields on the bioelectrochemical signal generated by sessile bacterial whole-cells in response to the presence of toxins was studied. It was demonstrated that

  5. Magnetic field enhanced cell uptake efficiency of magnetic silica mesoporous nanoparticles.

    Science.gov (United States)

    Liu, Qian; Zhang, Jixi; Xia, Weiliang; Gu, Hongchen

    2012-06-01

    The advantages of using magnetic mesoporous silica nanoparticles (M-MSNs) in biomedical applications have been widely recognized. However, poor uptake efficiency may hinder the potential of M-MSNs in many applications, such as cell tracking, drug delivery, fluorescence and magnetic resonance imaging. An external magnetic field may improve the cellular uptake efficiency. In this paper, we evaluated the effect of a magnetic field on the uptake of M-MSNs. We found that the internalization of M-MSNs by A549 cancer cells could be accelerated and enhanced by a magnetic field. An endocytosis study indicated that M-MSNs were internalized by A549 cells mainly through an energy-dependent pathway, namely clathrin-induced endocytosis. Transmission electron microscopy showed that M-MSNs were trafficked into lysosomes. With the help of a magnetic field, anticancer drug-loaded M-MSNs induced elevated cancer cell growth inhibition.

  6. VISUALIZATION OF LIP AND BASAL-CELL SKIN CANCER IN HIGH-FREQUENCY ELECTRICAL FIELD

    OpenAIRE

    Zabunyan G. A.; Ovsiyenko P. G.

    2015-01-01

    In patients, there has been registered luminescence of skin sites affected by basal cell skin cancer at stage III in high-frequency electric field. The diagnosis was confirmed by histological analysis of excised cancer sites

  7. Dark Matter in Low Surface Brightness Galaxies

    NARCIS (Netherlands)

    Blok, W. J. G. de; McGaugh, S. S.

    1996-01-01

    Abstract: Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that L

  8. Dark matter in low surface brightness galaxies

    NARCIS (Netherlands)

    de Blok, WJG; McGaugh, SS; Persic, M; Salucci, P

    1997-01-01

    Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that LSB galaxie

  9. Probable Bright Supernova discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-09-01

    A bright transient, which is a probable supernova, has been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  10. Brightness and darkness as perceptual dimensions.

    Directory of Open Access Journals (Sweden)

    Tony Vladusich

    2007-10-01

    Full Text Available A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D space varying from bright to dark. The results of many previous psychophysical studies suggest, by contrast, that achromatic colors are represented as points in a color space composed of two or more perceptual dimensions. The nature of these perceptual dimensions, however, presently remains unclear. Here we provide direct evidence that brightness and darkness form the dimensions of a two-dimensional (2-D achromatic color space. This color space may play a role in the representation of object surfaces viewed against natural backgrounds, which simultaneously induce both brightness and darkness signals. Our 2-D model generalizes to the chromatic dimensions of color perception, indicating that redness and greenness (blueness and yellowness also form perceptual dimensions. Collectively, these findings suggest that human color space is composed of six dimensions, rather than the conventional three.

  11. A photometric investigation of a bright Geminid

    NARCIS (Netherlands)

    Degewij, J.; Diggelen, Johannes van

    1968-01-01

    Photographic observations of meteors in the Netherlands started with a bright Geminid of photographic magnitude −8 observed on December 11, 1955, 21h39m55s by M. Alberts. From the assumed radiant and velocity we have constructed the trajectory of the bolide. The luminosity of the trail has been dete

  12. Alberta Associations for Bright Children Members' Handbook.

    Science.gov (United States)

    Alberta Association for Bright Children, Edmonton.

    This handbook is designed to provide information to parents of gifted children in Alberta, Canada. The handbook outlines the mission and objectives of the Alberta Associations for Bright Children and describes the structure of the non-profit organization. The booklet then addresses: (1) the characteristics of gifted children; (2) the rights of…

  13. Sample cell for in-field X-ray diffraction experiments

    Directory of Open Access Journals (Sweden)

    Viktor Höglin

    2015-01-01

    Full Text Available A sample cell making it possible to perform synchrotron radiation X-ray powder diffraction experiments in a magnetic field of 0.35 T has been constructed. The device is an add-on to an existing sample cell and contains a strong permanent magnet of NdFeB-type. Experiments have shown that the setup is working satisfactory making it possible to perform in-field measurements.

  14. Bright source lasers and experiments at very high irradiance

    International Nuclear Information System (INIS)

    The Los Alamos Bright Source has been assembled to explore the effects of intense coherent ultraviolet radiation on matter. This ultra-high brightness excimer laser is used to study the response of atoms, ions, and plasmas to the unique conditions the laser can provide. Primary areas of interest include properties and behavior of highly energetic atomic species, studies of possible intense field-induced nuclear transitions, pumping for x-ray lasers, and incoherent x-ray sources. The project consists of two phases: Los Alamos Bright Source I (LABS I) that is now in operation and is producing experimental data at an intensity up to 7 x 1017 watts/cm2 with 25 mJ of radiation and LABS II that will deliver between .1 and 1 J at an intensity of 1018 to 1020 w/cm2. At these high intensities we observe collisionless excitations to the KeV level. The exact nature of the excitation process is not known and is itself part of the investigation. Because of the coherent nature of the pump and the very large fields obtainable, new regimes of optical excitation can be expected and examined. Work is underway with LABS I to produce highly ionized species and measure their spectral and other properties. This equipment has proven to be highly reliable in the last year and should afford the opportunity for many basic studies. LABS II with its increased pulse energy and intensity will support studies involving larger pump volume and higher excitation levels. It should serve as a test bed for studies of pumping schemes for x-ray lasers. 6 refs., 8 figs., 3 tabs

  15. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise

    OpenAIRE

    Youngstedt, Shawn D.; Kline, Christopher E.; Elliott, Jeffrey A; Zielinski, Mark; Devlin, Tina M.; Moore, Teresa A.

    2016-01-01

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness...

  16. Effects of Potassium Currents upon Action Potential of Cardiac Cells Exposed to External Electric fields

    Institute of Scientific and Technical Information of China (English)

    An-Ying Zhang; Xiao-Feng Pang

    2008-01-01

    Previous studies show that exposure to high-voltage electric fields would influence the electro cardiogram both in experimental animate and human beings. The effects of the external electric fields upon action potential of cardiac cells are studied in this paper based on the dynamical model, LR91. Fourth order Runger-Kuta is used to analyze the change of potassium ion channels exposed to external electric fields in detail. Results indicate that external electric fields could influence the current of potassium ion by adding an induced component voltage on membrane. This phenomenon might be one of the reasons of heart rate anomaly under the high-voltage electric fields.

  17. Investigations on proton exchange membrane fuel cells with different configurations and flow fields

    Science.gov (United States)

    Kazim, Ayoub Mohamed

    In this study, two mathematical models are developed. The first one is a simple mathematical approach that computes all transport and electrochemical parameters inside the different layers of a fuel cell regardless of its configuration. Through heat and mass transfer analogy, convective mass transfer coefficients at different Reynolds number are determined for both concentric cylindrical and conventional proton exchange membrane (PEM) fuel cells. Concentrations of oxygen and hydrogen are then determined at each layer of the fuel cell using steady-state diffusion analysis. The concentration equations are solved together with the electrochemical equations inside the fuel cell, to obtain the fuel cell voltage and power density. The results from this simple approach compared well with the existing numerical and experimental results. The second mathematical model is to study PEM fuel cell with conventional and non-conventional namely interdigitated flow fields. Through proper handling of the boundary conditions at the gas diffusion/catalyst layer interface, the numerical solution of the model resulted in the profiles of transport and electrochemical parameters in the cathode. Parameters such as pressure distribution, velocity profile, oxygen concentration, molar flux, current density, polarization and overall power density at different cell over-potentials in both flow fields were determined. The results demonstrates the superiority of interdigitated flow field over the conventional type in terms of overall performance and illustrated the importance of the convective term of the species equation in enhancing the reaction rates, leading to a significant improvement in the fuel cell performance. The effects of different parameters, such as cathode porosity, inlet oxygen mole fraction, and operating pressure on fuel cell performance have been studied using this 2-D mathematical model. Finally, a simple efficiency and economical analysis was formulated and implemented on

  18. THE INFLUENCE OF MAGNETIC FIELDS ON INHIBITION OF MCF-7 CELL GROWTH BY TAMOXIFEN

    Science.gov (United States)

    THE INFLUENCE OF MAGNETIC FIELDS ON INHIBITION OF MCF-7 CELL GROWTH BY TAMOXIFEN.Harland and Liburdy (1) reported that 1.2-uT, 60-Hz magnetic fields could significantly block the inhibitory action of pharmacological levels of tamoxifen (10-7 M) on the growth of MCF-7 human br...

  19. Dynamics of Bright Solitons in Bose–Einstein Condensates with Complicated Potential

    International Nuclear Information System (INIS)

    We present analytical solutions of the one-dimensional nonlinear Schrodinger equations of Bose–Einstein condensates in an expulsive parabolic background with a complex potential and gravitational field, by performing the Darboux transformation from a trivial seed solution. It is shown that under a safe range of parameter, the shape of bright soliton can be controlled well by adjusting the experimental parameter of the ratio of axial oscillation to radial oscillation and feeding condensates from a thermal cloud. The gravitational field can change the contrail of the bright soliton trains without changing their peak and width

  20. A study of Magnetic Bright Points in the Na I D1 line

    CERN Document Server

    Jess, D B; Christian, D J; Crockett, P J; Keenan, F P

    2010-01-01

    High cadence, multiwavelength, optical observations of solar magnetic bright points, captured at disk center using the ROSA and IBIS imaging systems on the Dunn Solar Telescope, are presented. Magnetic bright points manifesting in the Na I D1 core are found to preferentially exist in regions containing strong downflows, in addition to co-spatial underlying photospheric magnetic field concentrations. Downdrafts within Na I D1 bright points exhibit speeds of up to 7km/s, with preferred structural symmetry in intensity, magnetic field and velocity profiles about the bright point center. Excess intensities associated with G-band and Ca II K observations of magnetic bright points reveal a power-law trend when plotted as a function of magnetic flux density. However, Na I D1 observations of the same magnetic features indicate an intensity plateau at weak magnetic field strengths below ~150G, suggesting the presence of a two-component heating process; one which is primarily acoustic, the other predominantly magnetic....

  1. Effects of AC magnetic field and carboxymethyldextran-coated magnetite nanoparticles on mice peritoneal cells

    International Nuclear Information System (INIS)

    A portable apparatus was developed to perform magnetohyperthermia (MHT) assays. In order to investigate its efficiency on cell lysis, biological effects of the AC magnetic field exposure after carboxymethyldextran-coated magnetite-nanoparticles (CMDC) treatment were investigated. Phagocyte capacity, cell viability, and morphology data evidenced that the CMDC sample and the apparatus are useful to further investigate MHT in cancer therapy

  2. Effects of AC magnetic field and carboxymethyldextran-coated magnetite nanoparticles on mice peritoneal cells

    Energy Technology Data Exchange (ETDEWEB)

    Araujo Guedes, Maria Helena [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil); Sadeghiani, Neda [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil); Lima Guedes Peixoto, Danielle [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil); Poubel Coelho, Julia [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil); Santos Barbosa, Luzirlane [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil); Bentes Azevedo, Ricardo [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil); Kueckelhaus, Selma [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil); Faculdade de Medicina, Universidade de Brasilia, Area de Morfologia, 70910-900 Brasilia-DF (Brazil); Silva, Maria de Fatima da [Nucleo de Fisica Aplicada, Instituto de Fisica, Universidade de Brasilia, 70919-970 Brasilia-DF (Brazil); Morais, Paulo Cesar [Nucleo de Fisica Aplicada, Instituto de Fisica, Universidade de Brasilia, 70919-970 Brasilia-DF (Brazil); Guerrero Marques Lacava, Zulmira [Depto de Genetica e Morfologia, Instituto de Ciencias Biologicas, Universidade de Brasilia, 70910-900 Brasilia-DF (Brazil)]. E-mail: zulmira@unb.br

    2005-05-15

    A portable apparatus was developed to perform magnetohyperthermia (MHT) assays. In order to investigate its efficiency on cell lysis, biological effects of the AC magnetic field exposure after carboxymethyldextran-coated magnetite-nanoparticles (CMDC) treatment were investigated. Phagocyte capacity, cell viability, and morphology data evidenced that the CMDC sample and the apparatus are useful to further investigate MHT in cancer therapy.

  3. Reproductive integrity of mammalian cells exposed to power frequency electromagnetic fields.

    Science.gov (United States)

    Livingston, G K; Witt, K L; Gandhi, O P; Chatterjee, I; Roti Roti, J L

    1991-01-01

    Human lymphocytes and Chinese hamster ovary (CHO) fibroblasts were analyzed for cytogenetic and cytotoxic endpoints to determine whether exposure to power frequency (60 Hz) electromagnetic fields (EMF) interferes with normal cell growth and reproduction. An exposure chamber was built to apply variable electric current densities of 3, 30, 300, and 3,000 microA/cm2, simultaneously with a fixed magnetic field of 2.2 G to proliferating cells. The current densities were chosen to bracket those that may be induced in the human body by fields measured beneath high voltage (765 kV) power transmission lines. The electric current was applied through the media of a cell culture chamber positioned between two stainless steel electrodes but separated from direct contact with the culture media by a salt bridge composed of a 1% agarose gel. The magnetic field was generated using two pairs of Helmholtz coils driven 73 degrees out of phase producing an elliptically polarized magnetic field 36 degrees out of phase with the electric field. The EMFs were measured and mapped inside the cell culture chamber to insure their uniformity. CHO cells were exposed continuously for 24-96 hr (depending on experiment) and human lymphocytes were exposed continuously for 72 hr. The EMFs were monitored throughout the entire treatment period using a multichannel chart recorder to verify continuous application of the desired fields. Sister-chromatid exchange and micronuclei were monitored to evaluate the potential for genotoxicity. In addition, standard growth curves, clonogenicity, and cell cycle kinetics were analyzed to evaluate possible cytotoxic effects. The experimental data consistently showed that the growth rate and reproductive integrity of both cell types was unaffected by exposure to the electromagnetic fields. PMID:1991460

  4. Static magnetic fields aggravate the effects of ionizing radiation on cell cycle progression in bone marrow stem cells.

    Science.gov (United States)

    Sarvestani, Amir Sabet; Abdolmaleki, Parviz; Mowla, Seyed Javad; Ghanati, Faezeh; Heshmati, Emran; Tavasoli, Zeinab; Jahromi, Azadeh Manoochehri

    2010-02-01

    In order to evaluate the influence of static magnetic fields (SMF) on the progression of cell cycle as a monitor of presumptive genotoxicity of these fields, the effects of a 15 mT SMF on cell cycle progression in rat bone marrow stem cells (BMSC) were examined. The cells were divided into two groups. One group encountered SMF alone for 5h continuously but the other group exposed with X ray before treatment with SMF. The population of cells did not show any significant difference in the first group but the second group that was exposed with acute radiation before encountering SMF showed a significant increase in the number of cells in G(2)/M phase. So SMF has intensified the effects of X ray, where SMF alone, did not had any detectable influence on cell cycle. These findings suggest that magnetic fields (MF) play their role by increasing the effects of genotoxic agents and because of the greater concentration of free radicals in the presence of radical pair producers, this effect is better detectable. PMID:19926297

  5. Design and Installation of a Disposal Cell Cover Field Test

    Energy Technology Data Exchange (ETDEWEB)

    Benson, C.H. [University of Wisconsin–Madison, Madison, Wisconsin; Waugh, W.J. [S.M. Stoller Corporation, Grand Junction, Colorado; Albright, W.H. [Desert Research Institute, Reno, Nevada; Smith, G.M. [Geo-Smith Engineering, Grand Junction, Colorado; Bush, R.P. [U.S. Department of Energy, Grand Junction, Colorado

    2011-02-27

    The U.S. Department of Energy’s Office of Legacy Management (LM) initiated a cover assessment project in September 2007 to evaluate an inexpensive approach to enhancing the hydrological performance of final covers for disposal cells. The objective is to accelerate and enhance natural processes that are transforming existing conventional covers, which rely on low-conductivity earthen barriers, into water balance covers, that store water in soil and release it as soil evaporation and plant transpiration. A low conductivity cover could be modified by deliberately blending the upper layers of the cover profile and planting native shrubs. A test facility was constructed at the Grand Junction, Colorado, Disposal Site to evaluate the proposed methodology. The test cover was constructed in two identical sections, each including a large drainage lysimeter. The test cover was constructed with the same design and using the same materials as the existing disposal cell in order to allow for a direct comparison of performance. One test section will be renovated using the proposed method; the other is a control. LM is using the lysimeters to evaluate the effectiveness of the renovation treatment by monitoring hydrologic conditions within the cover profile as well as all water entering and leaving the system. This paper describes the historical experience of final covers employing earthen barrier layers, the design and operation of the lysimeter test facility, testing conducted to characterize the as-built engineering and edaphic properties of the lysimeter soils, the calibration of instruments installed at the test facility, and monitoring data collected since the lysimeters were constructed.

  6. Pulsed Electromagnetic Field Stimulates Cellular Proliferation in Human Intervertebral Disc Cells

    OpenAIRE

    Lee, Hwan-Mo; Kwon, Un-Hye; Kim, Hyang; Kim, Ho-Joong; Kim, Boram; Park, Jin-Oh; Moon, Eun-Soo; Moon, Seong-Hwan

    2010-01-01

    Purpose The purpose of this study is to investigate the mechanism of cellular proliferation of electromagnetic field (EMF) on human intervertebral disc (IVD) cells. Materials and Methods Human IVD cells were cultured three-dimensionally in alginate beads. EMF was exposed to IVD cells with 650Ω, 1.8 millitesla magnetic flux density, 60 Hz sinusoidal wave. Cultures were divided into a control and EMF group. Cytotoxicity, DNA synthesis and proteoglycan synthesis were measured by MTT assay, [3H]-...

  7. From the Field to the Laboratory: Air Pollutant-Induced Genomic Effects in Lung Cells

    OpenAIRE

    William Vizuete; Sexton, Kenneth G.; Hang Nguyen; Lisa Smeester; Kjersti Marie Aagaard; Cynthia Shope; Barry Lefer; Flynn, James H.; Sergio Alvarez; Mathew H. Erickson; Fry, Rebecca C.

    2016-01-01

    Current in vitro studies do not typically assess cellular impacts in relation to real-world atmospheric mixtures of gases. In this study, we set out to examine the feasibility of measuring biological responses at the level of gene expression in human lung cells upon direct exposures to air in the field. This study describes the successful deployment of lung cells in the heavily industrialized Houston Ship Channel. By examining messenger RNA (mRNA) levels from exposed lung cells, we identified...

  8. Effect of internal electric field on InAs/GaAs quantum dot solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kasamatsu, Naofumi; Kada, Tomoyuki; Hasegawa, Aiko; Harada, Yukihiro; Kita, Takashi [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan)

    2014-02-28

    We studied time-resolved carrier recombination in InAs/GaAs quantum dot (QD) solar cells. The electric field in a p-i-n diode structure spatially separates photoexcited carriers in QDs, strongly affecting the conversion efficiency of intermediate-band solar cells. The radiative decay lifetime is dramatically reduced in a strong electric field (193 kV/cm) by efficient recombination due to strong carrier localization in each QD and significant tunneling-assisted electron escape. Conversely, an electric field of the order of 10 kV/cm maintains electronic coupling in the stacked QDs and diminishes tunneling-assisted electron escape.

  9. Effects of Pulsed Electromagnetic Field on Differentiation of HUES-17 Human Embryonic Stem Cell Line

    Directory of Open Access Journals (Sweden)

    Yi-Lin Wu

    2014-08-01

    Full Text Available Electromagnetic fields are considered to potentially affect embryonic development, but the mechanism is still unknown. In this study, human embryonic stem cell (hESC line HUES-17 was applied to explore the mechanism of exposure on embryonic development to pulsed electromagnetic field (PEMF for 400 pulses at different electric field intensities and the differentiation of HUES-17 cells was observed after PEMF exposure. The expression of alkaline phosphatase (AP, stage-specific embryonic antigen-3 (SSEA-3, SSEA-4 and the mRNA level and protein level of Oct4, Sox2 and Nanog in HUES-17 cells remained unchanged after PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m. Four hundred pulses PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m did not affect the differentiation of HUES-17 cells. The reason why electromagnetic fields affect embryonic development may be due to other mechanisms rather than affecting the differentiation of embryonic stem cells.

  10. Dielectrophoretic forces and potentials induced on pairs of cells in an electric field.

    Science.gov (United States)

    Foster, K R; Sowers, A E

    1995-09-01

    A combined numerical/experimental study is reported of the membrane potentials and dielectrophoretically induced forces between cells, membrane pressures, and velocity of attraction of cells under the influence of an electric field. This study was designed to explore electrical and mechanical effects produced by a field on cells in close proximity or undergoing electrically induced fusion. Laplace's equation for pairs of membrane-covered spheres in close proximity was solved numerically by the boundary element method, and the electrically induced forces on the cells and between cells were obtained by evaluating the Maxwell stress tensor. The velocity of approach of erythrocyte ghosts or fused ghosts in a 60-Hz field of 6 V/mm was measured experimentally, and the data were interpreted by using Batchelor's theory for hydrodynamic interaction of hard spheres. The numerical results show clearly the origin of the dielectrophoretic pressures and forces in fused and unfused cells and the effects of a nearby cell on the induced membrane potentials. The experimental results agree well with predictions based on the simple electrical model of the cell. The analysis shows the strong effect of hydrodynamic interactions between the cells in determining their velocity of approach. PMID:8519978

  11. DNA Comet Giemsa Staining for Conventional Bright-Field Microscopy

    OpenAIRE

    Andreyan Osipov; Ekaterina Arkhangelskaya; Alexei Vinokurov; Nadezhda Smetaninа; Alex Zhavoronkov; Dmitry Klokov

    2014-01-01

    This study was undertaken to evaluate the compatibility of Giemsa staining protocol with the comet assay. We showed, for the first time, that DNA comets can be visualized and analyzed using Giemsa staining. We generated DNA damage dose response curves for human peripheral blood lymphocytes exposed to X-ray radiation using the comet assay with either SybrGreen I or Giemsa stain. The dose response curves were fitted by linear regressions (R2 > 0.977). The SybrGreen I results showed only ~1.2...

  12. Experimental Study of Entropy Production in Cells under Alternating Electric Field

    Science.gov (United States)

    Ding, Chang-Jiang; Luo, Liao-Fu

    2012-08-01

    We put forward a new method for measuring the entropy production in the living cell. It involves heating the sample by alternating the electric field and recording the outward heat flow. The entropy production in a normal cell MCF10A and a cancerous cell MDA-MB-231 were measured and compared. The results show that the method is effective for the entropy measurement of a living organism. The scaled electro-induced entropy production rate (SEEP) of MDA-MB-231 monotonically increases with the electric field strength at 5-40 V/cm. While that of MCF10A changes non-monotonically and there exists a peak at 5-30 V/cm. The electro-induced entropy production ratio (EEPR) is smaller than 1 in a large range of field strengths, from 5 to 25 V/cm, which reveals that under 5-25 V/cm electric field exposure, the direction of the entropy flow may be changed from normal tissue to cancerous cells. We present a facile and effective strategy for experimentally investigating the thermodynamic properties of the cell and give a deeper insight into the physical difference between normal and cancerous cells under electric field exposure.

  13. Imaging Microwave and DC Magnetic Fields in a Vapor-Cell Rb Atomic Clock

    CERN Document Server

    Affolderbach, Christoph; Bandi, Thejesh; Horsley, Andrew; Treutlein, Philipp; Mileti, Gaetano

    2015-01-01

    We report on the experimental measurement of the DC and microwave magnetic field distributions inside a recently-developed compact magnetron-type microwave cavity, mounted inside the physics package of a high-performance vapor-cell atomic frequency standard. Images of the microwave field distribution with sub-100 $\\mu$m lateral spatial resolution are obtained by pulsed optical-microwave Rabi measurements, using the Rb atoms inside the cell as field probes and detecting with a CCD camera. Asymmetries observed in the microwave field images can be attributed to the precise practical realization of the cavity and the Rb vapor cell. Similar spatially-resolved images of the DC magnetic field distribution are obtained by Ramsey-type measurements. The T2 relaxation time in the Rb vapor cell is found to be position dependent, and correlates with the gradient of the DC magnetic field. The presented method is highly useful for experimental in-situ characterization of DC magnetic fields and resonant microwave structures,...

  14. In situ spatiotemporal mapping of flow fields around seeded stem cells at the subcellular length scale.

    Directory of Open Access Journals (Sweden)

    Min Jae Song

    Full Text Available A major hurdle to understanding and exploiting interactions between the stem cell and its environment is the lack of a tool for precise delivery of mechanical cues concomitant to observing sub-cellular adaptation of structure. These studies demonstrate the use of microscale particle image velocimetry (μ-PIV for in situ spatiotemporal mapping of flow fields around mesenchymal stem cells, i.e. murine embryonic multipotent cell line C3H10T1/2, at the subcellular length scale, providing a tool for real time observation and analysis of stem cell adaptation to the prevailing mechanical milieu. In the absence of cells, computational fluid dynamics (CFD predicts flow regimes within 12% of μ-PIV measures, achieving the technical specifications of the chamber and the flow rates necessary to deliver target shear stresses at a particular height from the base of the flow chamber. However, our μ-PIV studies show that the presence of cells per se as well as the density at which cells are seeded significantly influences local flow fields. Furthermore, for any given cell or cell seeding density, flow regimes vary significantly along the vertical profile of the cell. Hence, the mechanical milieu of the stem cell exposed to shape changing shear stresses, induced by fluid drag, varies with respect to proximity of surrounding cells as well as with respect to apical height. The current study addresses a previously unmet need to predict and observe both flow regimes as well as mechanoadaptation of cells in flow chambers designed to deliver precisely controlled mechanical signals to live cells. An understanding of interactions and adaptation in response to forces at the interface between the surface of the cell and its immediate local environment may be key for de novo engineering of functional tissues from stem cell templates as well as for unraveling the mechanisms underlying multiscale development, growth and adaptation of organisms.

  15. Influence of piezoelectric fields on InGaN based intermediate band solar cells

    Science.gov (United States)

    Tang, H.; Liu, B.; Wang, T.

    2015-01-01

    As it is practically infeasible to fabricate multiple-junction InGaN based tandem solar cells due to an intrinsic limit, intermediate-band solar cells (IBSCs) provide an alternative option for the fabrication of single-junction solar cells with their performance potentially equivalent to that of multiple-junction solar cells. InGaN quantum dots (QD) could be used for designing an IBSC structure. More importantly, it is well-known that there exist very strong piezoelectric fields in an InGaN/GaN system with a high indium composition, which becomes more pronounced for InGaN based QDs. The built-in piezoelectric fields can lead to a significant increase in the open circuit voltage and thus improved performance of solar cells, which has not yet been considered in designing III-nitride based solar cells so far. An optimized InGaN based QD-IBSC structure has been designed, combining the major advantages from the IBSC structure and the benefits due to the strong piezoelectric fields. A conversion efficiency, open-circuit voltage and short-circuit current have been calculated, and a highest conversion efficiency of 55.4% is obtained. The combination of the single-junction IBSC structure and the piezoelectric fields paves the way for the fabrication of InGaN based single-junction solar cells with ultra-high energy efficiency.

  16. Enhancing the brightness of Si nanocrystal light-emitting devices with electro-excited surface plasmons

    Science.gov (United States)

    Chen, Jia-Rong; Zhou, Zhi-Quan; Hao, Hong-Chen; Lu, Ming

    2014-09-01

    The use of electro-excited surface plasmons (SPs) in Ag nanoparticles (Ag-NPs) is shown to enhance the brightness of Si nanocrystal light-emitting devices (Si-NC LEDs). The Ag-NPs are prepared on the Si-NC thin film by ultrasonic irradiation and postannealing treatments. Electro-excited SPs on Ag-NPs are found, which are induced by electron impact on Ag-NPs and the front electrode Al layer during the charge injection process of LED. The electro-excited SPs enhance the electroluminescence of Si-NC, or LED brightness, via the SP field coupling to the exciton dipole moment of Si-NC. A maximal 5.2-fold brightness enhancement of Si-NC LED is achieved at the postannealing temperature of 200 °C. Remnant far-field radiations arising from electro-excited SPs are detected, which further supports the existence of such SPs.

  17. Improving sodium laser guide star brightness by polarization switching

    Science.gov (United States)

    Fan, Tingwei; Zhou, Tianhua; Feng, Yan

    2016-01-01

    Optical pumping with circularly polarized light has been used to enhance the brightness of sodium laser guide star. But the benefit is reduced substantially due to the precession of sodium atoms in geomagnetic field. Switching the laser between left and right circular polarization at the Larmor frequency is proposed to improve the return. With ESO’s laser guide star system at Paranal as example, numerical simulation shows that the return flux is increased when the angle between geomagnetic field and laser beam is larger than 60°, as much as 50% at 90°. The proposal is significant since most astronomical observation is at angle between 60° and 90° and it only requires a minor addition to the delivery optics of present laser system. PMID:26797503

  18. Quantum Bright Soliton in a Disorder Potential

    Science.gov (United States)

    Sacha, K.; Delande, D.; Zakrzewski, J.

    2009-11-01

    At very low temperature, a quasi-one-dimensional ensemble of atoms with attractive interactions tend to form a bright soliton. When exposed to a sufficiently weak external potential, the shape of the soliton is not modified, but its external motion is affected. We develop in detail the Bogoliubov approach for the problem, treating, in a non-perturbative way, the motion of the center of mass of the soliton. Quantization of this motion allows us to discuss its long time properties. In particular, in the presence of a disordered potential, the quantum motion of the center of mass of a bright soliton may exhibit Anderson localization, on a localization length which may be much larger than the soliton size and could be observed experimentally.

  19. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Steven Winter Associates, Inc., Norwalk, CT (United States); Butterfield, Karla [Steven Winter Associates, Inc., Norwalk, CT (United States)

    2016-03-01

    With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.

  20. Surface Brightness Fluctuations as Stellar Population Indicators

    OpenAIRE

    Blakeslee, John P

    2009-01-01

    Surface Brightness Fluctuations (SBF) can provide useful information about the unresolved stellar content of early-type galaxies and spiral bulges. The absolute SBF magnitude Mbar in a given passband depends on the properties of the stellar population and can be predicted by population synthesis models. SBF measurements in different bandpasses are sensitive to different evolutionary stages within the galaxy stellar population. Near-IR SBF magnitudes are sensitive to the evolution of stars wit...

  1. Extreme Ultraviolet Explorer Bright Source List

    Science.gov (United States)

    Malina, Roger F.; Marshall, Herman L.; Antia, Behram; Christian, Carol A.; Dobson, Carl A.; Finley, David S.; Fruscione, Antonella; Girouard, Forrest R.; Hawkins, Isabel; Jelinsky, Patrick

    1994-01-01

    Initial results from the analysis of the Extreme Ultraviolet Explorer (EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) are presented through the EUVE Bright Source List (BSL). The BSL contains 356 confirmed extreme ultraviolet (EUV) point sources with supporting information, including positions, observed EUV count rates, and the identification of possible optical counterparts. One-hundred twenty-six sources have been detected longward of 200 A.

  2. Particle-in-cell simulations of plasma opening switch with external magnetic field

    International Nuclear Information System (INIS)

    Fully electromagnetic particle-in-cell simulations are performed to study the effects of an external magnetic field on coaxial plasma opening switch (POS). The simulation results show that POS opening performance can be significantly improved only when external longitudinal magnetic field coils are placed at the cathode side, and an additional azimuthal magnetic field is effective whether the central electrode is of positive or negative polarity. Voltage multiplication coefficient K rises with the additional magnetic field increasing till the electron current is completely magnetically insulated during the opening of POS

  3. Cell death induced by AC magnetic fields and magnetic nanoparticles: current state and perspectives.

    Science.gov (United States)

    Goya, Gerardo F; Asín, Laura; Ibarra, M Ricardo

    2013-12-01

    This review analyses the advances in the field of magnetically induced cell death using intracellular magnetic nanoparticles (MNPs). Emphasis has been given to in vitro research results, discussing the action of radiofrequency (RF) waves on biological systems as well as those results of thermally induced cell death in terms of MNP cell interactions. Our main goal has been to provide a unified depiction of many recent experiments and theoretical models relevant to the effect of applied electromagnetic fields on MNPs after cellular uptake and the cytotoxicity assessment of MNPs. We have addressed the effects of RF waves used for in vitro magnetic hyperthermia on eukaryotic cells regarding physical modifications of the cellular local environment and cell viability.

  4. The Bright SHARC Survey The Cluster Catalog

    CERN Document Server

    Romer, A K; Holden, B P; Ulmer, M P; Pildis, R A; Merrelli, A J; Adami, C; Burke, D J; Collins, C A; Metevier, A J; Kron, Richard G; Commons, K

    1999-01-01

    We present the Bright SHARC (Serendipitous High-Redshift Archival ROSAT Cluster) Survey, which is an objective search for serendipitously detected extended X-ray sources in 460 deep ROSAT PSPC pointings. The Bright SHARC Survey covers an area of 178.6 sq.deg and has yielded 374 extended sources. We discuss the X-ray data reduction, the candidate selection and present results from our on-going optical follow-up campaign. The optical follow-up concentrates on the brightest 94 of the 374 extended sources and is now 97% complete. We have identified thirty-seven clusters of galaxies, for which we present redshifts and luminosities. The clusters span a redshift range of 0.0696Bright SHARC clusters have not been listed in any previously ...

  5. Search for bright stars with infrared excess

    International Nuclear Information System (INIS)

    Bright stars, stars with visual magnitude smaller than 6.5, can be studied using small telescope. In general, if stars are assumed as black body radiator, then the color in infrared (IR) region is usually equal to zero. Infrared data from IRAS observations at 12 and 25μm (micron) with good flux quality are used to search for bright stars (from Bright Stars Catalogues) with infrared excess. In magnitude scale, stars with IR excess is defined as stars with IR color m12−m25>0; where m12−m25 = −2.5log(F12/F25)+1.56, where F12 and F25 are flux density in Jansky at 12 and 25μm, respectively. Stars with similar spectral type are expected to have similar color. The existence of infrared excess in the same spectral type indicates the existence of circum-stellar dust, the origin of which is probably due to the remnant of pre main-sequence evolution during star formation or post AGB evolution or due to physical process such as the rotation of those stars

  6. LA Palma Night-Sky Brightness

    CERN Document Server

    Benn, C R; Benn, Chris R.; Ellison, Sara L.

    1998-01-01

    The brightness of the moonless night sky above La Palma was measured on 427 CCD images taken with the Isaac Newton and Jacobus Kapteyn Telescopes on 63 nights during 1987 - 1996. The median sky brightness at high elevation, high galactic latitude and high ecliptic latitude, at sunspot minimum, is B = 22.7, V = 21.9, R = 21.0, similar to that at other dark sites. The main contributions to sky brightness are airglow and zodiacal light. The sky is brighter at low ecliptic latitude (by 0.4 mag); at solar maximum (by 0.4 mag); and at high airmass (0.25 mag brighter at airmass 1.5). Light pollution (line + continuum) contributes < 0.03 mag in U, approximately 0.02 mag in B, approximately 0.10 mag in V, approximately and 0.10 mag in R at the zenith. This paper is a summary of results which are presented in full elsewhere (Benn & Ellison 1998, La Palma Technical Note 115).

  7. Thermal Field Analysis and Simulation of an Infrared Belt Furnace Used for Solar Cells

    Directory of Open Access Journals (Sweden)

    Bai Lu

    2014-01-01

    Full Text Available During solar cell firing, volatile organic compounds (VOC and a small number of metal particles were removed using the gas flow. When the gas flow was disturbed by the thermal field of infrared belt furnace and structure, the metal particles in the discharging gas flow randomly adhered to the surface of solar cell, possibly causing contamination. Meanwhile, the gas flow also affected the thermal uniformity of the solar cell. In this paper, the heating mechanism of the solar cell caused by radiation, convection, and conduction during firing was analyzed. Afterward, four 2-dimensional (2D models of the furnace were proposed. The transient thermal fields with different gas inlets, outlets, and internal structures were simulated. The thermal fields and the temperature of the solar cell could remain stable and uniform when the gas outlets were installed at the ends and in the middle of the furnace, with the gas inlets being distributed evenly. To verify the results, we produced four types of furnaces according to the four simulated results. The experimental results indicated that the thermal distribution of the furnace and the characteristics of the solar cells were consistent with the simulation. These experiments improved the efficiency of the solar cells while optimizing the solar cell manufacturing equipment.

  8. Responses of human MG-63 osteosarcoma cell line and human osteoblast-like cells to pulsed electromagnetic fields.

    Science.gov (United States)

    Sollazzo, V; Traina, G C; DeMattei, M; Pellati, A; Pezzetti, F; Caruso, A

    1997-01-01

    We have studied the effects of low-energy, low-frequency pulsed electromagnetic fields (PEMF) on cell proliferation, in both human osteoblast-like cells obtained from bone specimens and in human MG-63 osteosarcoma cell line. Assessment of osteoblastic phenotype was performed both by immunolabeling with antiosteonectin antibody and by verifying the presence of parathyroid hormone receptors. The cells were placed in multiwell plates and set in a tissue culture incubator between a pair of Helmholtz coils powered by a pulse generator (1.3 ms, 75 Hz) for different periods of time. [3H]Thymidine incorporation was used to evaluate cell proliferation. Since it had previously been observed that the osteoblast proliferative response to PEMF exposure may also be conditioned by the presence of serum in the medium, experiments were carried out at different serum concentrations. [3H]Thymidine incorporation increases in osteoblast-like cells, when they are exposed to PEMF in the presence of 10% fetal calf serum (FCS). The greatest effect is observed after 24 hours of PEMF exposure. No effects on cell proliferation are observed when osteoblast-like cells are exposed to PEMF in the presence of 0.5% FCS or in a serum-free medium. On the other hand, PEMF-exposed MG-63 cells show increased cell proliferation either at 10% FCS, 0.5% FCS and in serum-free medium. Nevertheless, the maximum effect of PEMF exposure on MG-63 cell proliferation depends on the percentage of FCS in the medium. The higher the FCS concentration, the faster the proliferative response to PEMF exposure. Our results show that, although MG-63 cells display some similarity with human bone cells, their responses to PEMF's exposure are quite different from that observed in normal human bone cells. PMID:9383242

  9. The effect of electric and magnetic fields on the operation of a photovoltaic cell

    Energy Technology Data Exchange (ETDEWEB)

    Erel, Serafettin [Department of Physics, Faculty of Science and Letters, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)

    2002-02-01

    In this work, we have investigated the effects of electric and magnetic fields on the operation of a CdS/CuInSe{sub 2} photovoltaic cell. Various electric field intensities changing from 0 to 35000V{sub dc}/m, were applied to the sample while it was irradiated by a He-Ne laser with a wavelength {lambda}=670nm. As a result, the typical values for the open circuit voltage of the photovoltaic cell significantly changed with various intensities of the electric field E{sub dc}. We also applied magnetic fields varying from 0.003 to 0.079T using a solenoid with an inductance of 10.55mH and the response of the sample was observed. In the third step of the experiment, instead of the laser beam, various intensities of white light of 50, 100,150 and also 250lux were utilised. 250lux was measured to be equivalent to the radiation power of He-Ne laser beam on the surface of the photovoltaic cell. The effect of electric fields from 0 up to 3x10{sup 5}V{sub dc} was applied and some significant experimental results were obtained. As a result of the illumination of the photovoltaic cell by the stimulated and spontaneous light emission sources under the effect of various intensities of electric field E{sub dc}, different electrical behaviours were observed.

  10. Helium atmospheric pressure plasma jets interacting with wet cells: delivery of electric fields

    Science.gov (United States)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2016-05-01

    The use of atmospheric pressure plasma jets (APPJs) in plasma medicine have produced encouraging results in wound treatment, surface sterilization, deactivation of bacteria, and treatment of cancer cells. It is known that many of the reactive oxygen and nitrogen species produced by the APPJ are critical to these processes. Other key components to treatment include the ion and photon fluxes, and the electric fields produced in cells by the ionization wave of the APPJ striking in the vicinity of the cells. These relationships are often complicated by the cells being covered by a thin liquid layer—wet cells. In this paper, results from a computational investigation of the interaction of APPJs with tissue beneath a liquid layer are discussed. The emphasis of this study is the delivery of electric fields by an APPJ sustained in He/O2  =  99.8/0.2 flowing into humid air to cells lying beneath water with thickness of 200 μm. The water layer represents the biological fluid typically covering tissue during treatment. Three voltages were analyzed—two that produce a plasma effluent that touches the surface of the water layer and one that does not touch. The effect of the liquid layer thickness, 50 μm to 1 mm, was also examined. Comparisons were made of the predicted intracellular electric fields to those thresholds used in the field of bioelectronics.

  11. Electromagnetic field effects on cells of the immune system: The role of calcium signaling

    Energy Technology Data Exchange (ETDEWEB)

    Walleczek, J. (Lawrence Berkeley Lab., CA (United States))

    1992-10-01

    During the past decade considerable evidence has accumulated demonstrating that nonthermal exposures of cells of the immune system to extremely low-frequency (ELF) electromagnetic fields (< 300 Hz) can elicit cellular changes that might be relevant to in vivo immune activity. A similar responsiveness to nonionizing electromagnetic energy in this frequency range has also been documented for tissues of the neuroendocrine and musculoskeletal system. However, knowledge about the underlying biological mechanisms by which such fields can induce cellular changes is still very limited. It is generally believed that the cell membrane and Ca[sup 2+]-regulated activity is involved in bioactive ELF field coupling to living systems. This article begins with a short review of the current state of knowledge concerning the effects of nonthermal levels of ELF electromagnetic fields on the biochemistry and activity of immune cells and then closely examines new results that suggest a role for Ca[sup 2+] in the induction of these cellular field effects. Based on these findings it is proposed that membrane-mediated Ca[sup 2+] in the induction of these cellular field effects. Based on these findings it is proposed that membrane-mediated Ca[sup 2+] signaling processes are involved in the mediation of field effects on the immune system. 69 refs., 2 tabs.

  12. Electroporation of cells using EM induction of ac fields by a magnetic stimulator

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C; Robinson, M P [Department of Electronics, University of York, Heslington, York YO10 5DD (United Kingdom); Evans, J A [Academic Unit of Medical Physics, University of Leeds, Leeds LS2 9JT (United Kingdom); Smye, S W [Department of Medical Physics and Engineering, Leeds Teaching Hospitals, St. James' s University Hospital, Leeds LS9 7TF (United Kingdom); O' Toole, P [Department of Biology, University of York, Heslington, York YO10 5DD (United Kingdom)

    2010-02-21

    This paper describes a method of effectively electroporating mammalian cell membranes with pulsed alternating-current (ac) electric fields at field strengths of 30-160 kV m{sup -1}. Although many in vivo electroporation protocols entail applying square wave or monotonically decreasing pulses via needles or electrode plates, relatively few have explored the use of pulsed ac fields. Following our previous study, which established the effectiveness of ac fields for electroporating cell membranes, a primary/secondary coil system was constructed to produce sufficiently strong electric fields by electromagnetic induction. The primary coil was formed from the applicator of an established transcranial magnetic stimulation (TMS) system, while the secondary coil was a purpose-built device of a design which could eventually be implanted into tissue. The effects of field strength, pulse interval and cumulative exposure time were investigated using microscopy and flow cytometry. Results from experiments on concentrated cell suspensions showed an optimized electroporation efficiency of around 50%, demonstrating that electroporation can be practicably achieved by inducing such pulsed ac fields. This finding confirms the possibility of a wide range of in vivo applications based on magnetically coupled ac electroporation.

  13. The magnetic field of Betelgeuse: a local dynamo from giant convection cells?

    CERN Document Server

    Auriere, M; Konstantinova-Antova, R; Perrin, G; Petit, P; Roudier, T

    2010-01-01

    Betelgeuse is an M supergiant with a complex and extended atmosphere, which also harbors spots and giant granules at its surface. A possible magnetic field could contribute to the mass loss and to the heating of the outer atmosphere. We observed Betelgeuse, to directly study and infer the nature of its magnetic field. We used the new-generation spectropolarimeter NARVAL and the least square deconvolution (LSD) method to detect circular polarization within the photospheric absorption lines of Betelgeuse. We have unambiguously detected a weak Stokes V signal in the spectral lines of Betelgeuse, and measured the related surface-averaged longitudinal magnetic field Bl at 6 different epochs over one month. The detected longitudinal field is about one Gauss and is apparently increasing on the time scale of our observations. This work presents the first direct detection of the magnetic field of Betelgeuse. This magnetic field may be associated to the giant convection cells that could enable a "local dynamo:.

  14. Properties of Galaxies in the Disc Central Surface Brightness Gap

    CERN Document Server

    Sorce, Jenny G; Libeskind, Noam I

    2015-01-01

    Intermediate surface brightness (ISB) galaxies are less numerous than their counterparts at high and low surface brightness (HSB and LSB). Investigating ISB characteristics from a sample from the S4G survey, complete down to M_B=-16, we find that they have intermediate stellar, gas and baryonic masses and on average as much gas as stars. They lie on the (baryonic) Tully-Fisher relation between HSBs and LSBs, although they present a higher scatter than the latter. Their stellar to baryonic mass ratios have intermediate values unlike their condensed baryonic fractions. By comparing their environments, as classified by the eigenvalues of the velocity shear tensor of local constrained simulations, ISBs have a 5-10% probability higher (smaller) to be in sheets (filaments) with respect to HSBs and LSBs. Additionally, for galaxies in filaments (with close neighbors), the mass and mu_0 are correlated at 2.5 (2) sigma more than for those in sheets. ISBs live in regions where the divergence of the velocity field is sma...

  15. Properties of galaxies in the disc central surface brightness gap

    Science.gov (United States)

    Sorce, Jenny G.; Creasey, Peter; Libeskind, Noam I.

    2016-01-01

    Intermediate surface brightness (ISB) galaxies are less numerous than their counterparts at high and low surface brightness (HSB and LSB). Investigating ISB characteristics from a sample from the Spitzer Survey of Stellar Structure in Galaxies survey, complete down to MB = -16, we find that they have intermediate stellar, gas and baryonic masses and on average as much gas as stars. They lie on the (baryonic) Tully-Fisher relation between HSBs and LSBs, although they present a higher scatter than the latter. Their stellar to baryonic mass ratios have intermediate values unlike their condensed baryonic fractions. By comparing their environments, as classified by the eigenvalues of the velocity shear tensor of local constrained simulations, ISBs have a 5-10 per cent probability higher (smaller) to be in sheets (filaments) with respect to HSBs and LSBs. Additionally, for galaxies in filaments (with close neighbours), the mass and μ0 are correlated at 2.5 (2)σ more than for those in sheets. ISBs live in regions where the divergence of the velocity field is smaller than where HSBs and LSBs live, a result at more than 50 per cent significance. ISBs may exist as an unstable transition state between LSBs and HSBs, the low flow activity environment maximally encouraging their formation. Interaction events altering the central baryon fraction could happen at a lower rate in these less dense environment, whilst in the higher density environments the LSBs are primarily satellite galaxies, whose accretion is sufficiently constrained that it fails to promote them to HSBs.

  16. New low surface brightness dwarf galaxies in the Centaurus group

    CERN Document Server

    Müller, Oliver; Binggeli, Bruno

    2016-01-01

    We conducted an extensive CCD search for faint, unresolved dwarf galaxies of very low surface brightness in the whole Centaurus group region encompassing the Cen A and M 83 subgroups lying at a distance of roughly 4 and 5 Mpc, respectively. The aim is to significantly increase the sample of known Centaurus group members down to a fainter level of completeness, serving as a basis for future studies of the 3D structure of the group. Following our previous survey of 60 square degrees covering the M 83 subgroup, we extended and completed our survey of the Centaurus group region by imaging another 500 square degrees area in the g and r bands with the wide-field Dark Energy Survey Camera at the 4m Blanco telescope at CTIO. The limiting central surface brightness reached for suspected Centaurus members is $\\mu_r \\approx 29$ mag arcsec$^{-2}$, corresponding to an absolute magnitude $M_r \\approx -9.5$. The images were enhanced using different filtering techniques. We found 41 new dwarf galaxy candidates, which togethe...

  17. Ultra Low Surface Brightness Imaging with the Dragonfly Telephoto Array

    CERN Document Server

    Abraham, Roberto G

    2014-01-01

    We describe the Dragonfly Telephoto Array, a robotic imaging system optimized for the detection of extended ultra low surface brightness structures. The array consists of eight Canon 400mm f/2.8 telephoto lenses coupled to eight science-grade commercial CCD cameras. The lenses are mounted on a common framework and are co-aligned to image simultaneously the same position on the sky. The system provides an imaging capability equivalent to a 0.4m aperture f/1.0 refractor with a 2.6 deg X 1.9 deg field of view. The system has no obstructions in the light path, optimized baffling, and internal optical surfaces coated with a new generation of anti-reflection coatings based on sub-wavelength nanostructures. As a result, the array's point spread function has a factor of ~10 less scattered light at large radii than well-baffled reflecting telescopes. The Dragonfly Telephoto Array is capable of imaging extended structures to surface brightness levels below 30 mag/arcsec^2 in 10h integrations (without binning or foregro...

  18. Effects of short-term IOP elevation on receptive field properties of cat LGN cells

    Institute of Scientific and Technical Information of China (English)

    TAO Liming; ZHANG Nan; YE Xiang; ZHOU Yifeng

    2004-01-01

    To investigate the effects of short-term intraocular pressure (IOP) elevation on the receptive field properties of lateral geniculate nucleus (LGN) cells, responses of the LGN cells to annulus, disc and drifting gratings with high or low spatial frequencies have been recorded extracellularly in the cat with the retinal perfusion pressure kept stable (30mmHg). Our results indicated that the responses of the X and Y type LGN cells were significantly weakened during IOP elevation. And the responses varied with the different mechanisms of receptive fields. Specifically, while using annulus and disc as stimuli, the responses of Y cells were more tolerant than X cells to IOP elevation. The surround area of the receptive field was more sensitive to IOP elevation than the center. The mean responses during IOP elevation decreased more than the peak responses did. IOP elevation has more influence on the responses of X cells than on the response of Y cells to the drifting gratings with high spatial frequency. These results may reflect different degrees of ischemia on corresponding retinal structures caused by IOP elevation.

  19. Relaxation rates of low-field gas-phase ^129Xe storage cells

    Science.gov (United States)

    Limes, Mark; Saam, Brian

    2010-10-01

    A study of longitudinal nuclear relaxation rates T1 of ^129Xe and Xe-N2 mixtures in a magnetic field of 3.8 mT is presented. In this regime, intrinsic spin relaxation is dominated by the intramolecular spin-rotation interaction due to persistent xenon dimers, a mechanism that can be quelled by introducing large amounts of N2 into the storage cell. Extrinsic spin relaxation is dominated by the wall-relaxation rate, which is the primary quantity of interest for the various low-field storage cells and coatings that we have tested. Previous group work has shown that extremely long gas-phase relaxation times T1 can be obtained, but only at large magnetic fields and low xenon densities. The current work is motivated by the practical benefits of retaining hyperpolarized ^129Xe for extended periods of time in a small magnetic field.

  20. Deformation of biological cells in the acoustic field of an oscillating bubble

    OpenAIRE

    Zinin, Pavel V.; Allen, John S.

    2009-01-01

    In this work we develop a theoretical framework of the interaction of microbubbles with bacteria in the ultrasound field using a shell model of the bacteria, following an approach developed previously [P. V. Zinin et al., Phys. Rev. E 72, 61907 (2005)]. Within the shell model, the motion of the cell in an ultrasonic field is determined by the motion of three components: the internal viscous fluid, a thin elastic shell, and the surrounding viscous fluid. Several conclusions can be drawn from t...

  1. Interplays between charge and electric field in perovskite solar cells: charge transport, recombination and hysteresis

    OpenAIRE

    Shi, Jiangjian; Zhang, Huiyin; Xu, Xin; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

    2016-01-01

    Interplays between charge and electric field, which play a critical role in determining the charge transport, recombination, storage and hysteresis in the perovskite solar cell, have been systematically investigated by both electrical transient experiments and theoretical calculations. It is found that the light illumination can increase the carrier concentration in the perovskite absorber, thus enhancing charge recombination and causing the co-existence of high electric field and free carrie...

  2. FEM simulations and experimental studies of the temperature field in a large diamond crystal growth cell

    Institute of Scientific and Technical Information of China (English)

    Li Zhan-Chang; Jia Xiao-Peng; Huang Guo-Feng; Hu Mei-Hua; Li Yong; Yan Bing-Min; Ma Hong-An

    2013-01-01

    We investigate the temperature field variation in the growth region of a diamond crystal in a sealed cell during the whole process of crystal growth by using the temperature gradient method (TGM) at high pressure and high temperature (HPHT).We employ both the finite element method (FEM) and in situ experiments.Simulation results show that the temperature in the center area of the growth cell continues to decrease during the process of large diamond crystal growth.These results are in good agreement with our experimental data,which demonstrates that the finite element model can successfully predict the temperature field variations in the growth cell.The FEM simulation will be useful to grow larger high-quality diamond crystal by using the TGM.Furthermore,this method will be helpful in designing better cells and improving the growth process of gem-quality diamond crystal.

  3. FEM simulations and experimental studies of the temperature field in a large diamond crystal growth cell

    International Nuclear Information System (INIS)

    We investigate the temperature field variation in the growth region of a diamond crystal in a sealed cell during the whole process of crystal growth by using the temperature gradient method (TGM) at high pressure and high temperature (HPHT). We employ both the finite element method (FEM) and in situ experiments. Simulation results show that the temperature in the center area of the growth cell continues to decrease during the process of large diamond crystal growth. These results are in good agreement with our experimental data, which demonstrates that the finite element model can successfully predict the temperature field variations in the growth cell. The FEM simulation will be useful to grow larger high-quality diamond crystal by using the TGM. Furthermore, this method will be helpful in designing better cells and improving the growth process of gem-quality diamond crystal. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. Field collapse due to band-tail charge in amorphous silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qi; Crandall, R.S. [National Renewable Energy Lab., Golden, CO (United States); Schiff, E.A. [Syracuse Univ., NY (United States)

    1996-05-01

    It is common for the fill factor to decrease with increasing illumination intensity in hydrogenated amorphous silicon solar cells. This is especially critical for thicker solar cells, because the decrease is more severe than in thinner cells. Usually, the fill factor under uniformly absorbed red light changes much more than under strongly absorbed blue light. The cause of this is usually assumed to arise from space charge trapped in deep defect states. The authors model this behavior of solar cells using the Analysis of Microelectronic and Photonic Structures (AMPS) simulation program. The simulation shows that the decrease in fill factor is caused by photogenerated space charge trapped in the band-tail states rather than in defects. This charge screens the applied field, reducing the internal field. Owing to its lower drift mobility, the space charge due to holes exceeds that due to electrons and is the main cause of the field screening. The space charge in midgap states is small compared with that in the tails and can be ignored under normal solar-cell operating conditions. Experimentally, the authors measured the photocapacitance as a means to probe the collapsed field. They also explored the light intensity dependence of photocapacitance and explain the decrease of FF with the increasing light intensity.

  5. Electromagnetic field effects on cells of the immune system: The role of calcium signalling

    Energy Technology Data Exchange (ETDEWEB)

    Walleczek, J.

    1991-07-01

    During the past decade considerable evidence has accumulated demonstrating the exposures of cells of the immune system to relatively weak extremely-low-frequency (ELF) electromagnetic fields (< 300 Hz) can elicit cellular changes which might be relevant to in-vivo immune activity. However, knowledge about the underlying biological mechanisms by which weak fields induce cellular changes is still very limited. It is generally believed that the cell membrane and Ca{sup 2+} regulated activity is involved in bioactive ELF field-coupling to living systems. This article begins with a short review of the current state of knowledge concerning the effects of nonthermal levels of ELF electromagnetic fields on the biochemistry and activity of immune cells, and then closely examines new results which suggest a role for Ca{sup 2+} in the induction of these cellular field effects. Based on these findings it is proposed that membrane-mediated Ca{sup 2+} signalling processes are involved in the mediation of field effects on the immune system. 64 refs., 2 tabs.

  6. Exciton Distribution between the Bright and Dark States in Single Carbon Nanotubes Studied by Magneto-Photoluminescence Spectroscopy

    Science.gov (United States)

    Matsunaga, Ryusuke; Matsuda, Kazunari; Kanemitsu, Yoshihiko

    2009-03-01

    We have performed micro-photoluminescence (PL) spectroscopy for single carbon nanotubes under magnetic fields at various temperatures. Sharp PL spectra of single carbon nanotubes allow us to directly observe the dark exciton PL peak a few meV below the bright exciton PL peak due to the Aharonov-Bohm effect [1]. From the PL intensity ratio of the dark to the bright excitons under magnetic fields, we found that the non-equilibrium (non-Boltzmann) distribution occurs between the bright and dark states, because phonons cannot scatter excitons between the two states with different parities [2]. Furthermore, we discuss the diameter dependence of the exciton population of the bright and dark states in single carbon nanotubes. [1] R. Matsunaga, K. Matsuda, and Y. Kanemitsu, Phys. Rev. Lett. 101, 147404 (2008). [2] V. Perebeinos, J. Tersoff, and Ph. Avouris, Nano Lett. 5, 2495 (2005).

  7. The Use of Solar Cell in Ground Water Irrigation to Support Agricultural Cultivation in Rainfed Field

    OpenAIRE

    Delvi Yanti

    2016-01-01

    This research aims at developing the use of solar cell to water the ground water irrigation in order to support agricultural cultivation in rain-fed field. The location of this research was agricultural land (ricefield) in Singkarak village, X Koto Singkarak sub-district, Solok district. This research was conducted with the design and technical test of ground water irrigation with solar cell, the analysis of irrigation water demand with crop-wat and the analysis of financial feasibility. The ...

  8. Dendritic field size and morphology of midget and parasol ganglion cells of the human retina.

    OpenAIRE

    Dacey, D M; Petersen, M R

    1992-01-01

    The visual system of the macaque monkey has provided a useful model for understanding the neural basis of human vision, yet, there are few detailed comparisons of neural populations other than photoreceptors for the two species. Using intracellular staining in an in vitro preparation of the isolated and intact human retina, we have characterized the relationship of dendritic field size to retinal eccentricity for the two major ganglion cell classes, the midget and the parasol cells. We report...

  9. Induction of growth and proliferation of fibroblast cells in magnetic field

    Directory of Open Access Journals (Sweden)

    Naghmeh Ezatti

    2015-02-01

    Full Text Available Background: Tissue engineering is generally defined as developing and changing the laboratory growth of molecules and cells in tissues or organs to replace and repair the damaged part of body. This study was carried out to stimulate the growth of cultured fibroblast cells by a physical electromagnetic method. Methods: First, an air-core coil was prepared and the cell culture plate was placed comfortably into the mold, then the plate containing the culture medium and human fibroblast cell along with air-core coil were placed in an incubator and then connected to the power supply. Thus, the sample underwent electromagnetic field at different times, and cell proliferation was studied by MTTassay. Results: Microscopic images indicated that the cells undergoing electromagnetic field (0.35 amps had a significant growth compared to the cells in control group in a definit range of stimulation. Conclusion: In conclusion, electromagnetic stimulation in a definite range led to cell proliferation and could be used as a positive factor in tissue engineering.

  10. Electric-field-induced change of alkali-metal vapor density in paraffin-coated cells

    CERN Document Server

    Kimball, D F Jackson; Ravi, K; Sharma, Arijit; Prabhudesai, Vaibhav S; Rangwala, S A; Yashchuk, V V; Balabas, M V; Budker, D

    2008-01-01

    Alkali vapor cells with antirelaxation coating (especially paraffin-coated cells) have been a central tool in optical pumping and atomic spectroscopy experiments for 50 years. We have discovered a dramatic change of the alkali vapor density in a paraffin-coated cell upon application of an electric field to the cell. A systematic experimental characterization of the phenomenon is carried out for electric fields ranging in strength from 0-8 kV/cm for paraffin-coated cells containing rubidium and cells containing cesium. The typical response of the vapor density to a rapid (duration < 100 ms) change in electric field of sufficient magnitude includes (a) a rapid (duration of < 100 ms) and significant increase in alkali vapor density followed by (b) a less rapid (duration of ~ 1 s) and significant decrease in vapor density (below the equilibrium vapor density), and then (c) a slow (duration of ~ 100 s) recovery of the vapor density to its equilibrium value. Measurements conducted after the alkali vapor densi...

  11. Sterilization of Escherichia coli cells by the application of pulsed magnetic field

    Institute of Scientific and Technical Information of China (English)

    LI Mei; QU Jiu-hui; PENG Yong-zhen

    2004-01-01

    The inactivation of microorganisms by pulsed magnetic field was studied. It was improved that theapplication of electromagnetic pulses evidently causes a lethal effect on E. coli cells suspended in phosphate buffersolution Na2 HPO4 / NaH2 PO4 (0.334/0.867 mmol/L). Experimental results indicated that the survivability( N/N0; whereN0 and N are the number of cells survived per milliliter before and after electromagnetic pulses application,respectively) of E. coli decreased with magnetic field intensity B and treatment time t. It was also found that themedium temperatures, the frequencies of pulse f, and the initial bacterial cell concentrations have determinateinfluences in destruction of E. coli cells by the application of magnetic pulses. The application of an magneticintensity B = 160 mT at pulses frequency f = 62 kHz and treatment time t = 16 h result in a considerable destructionlevels of E. coli cells ( N/N0 = 10-4 ). Possible mechanisms involved in sterilization of the magnetic field treatmentwere discussed. In order to shorten the treatment time, many groups of parallel inductive coil were used. Thepracticability test showed that the treatment time was shortened to 4 h with the application of three groups of parallelcoil when the survivability of E. coli cells was less than 0.01%; and the power consumption was about 0.2 kWh/m3 .

  12. Proliferation and differentiation of rat bone marrow stem cells by 400μT electromagnetic field.

    Science.gov (United States)

    Safari, Manouchehr; Jadidi, Majid; Baghian, Atefeh; Hasanzadeh, Hadi

    2016-01-26

    The interaction between environment electromagnetic field (EMF) and cells can effect on various physiological processes. EMF as an external inducing factor, could effect on proliferation or differentiation of cells. The purpose of this study was to evaluate the influence of the electromagnetic field on the viability, proliferation and differentiation rate of bone marrow stem cells (BMSCs) to neuron. BMSCs were obtained from 42 adult male rats. The cells incubated and cultured in 96-wells and 6-wells plates and exposed to electromagnetic field (40 or 400μT) with a selected waveform: AC (alternative current), rectified half wave (RHW) and rectified full wave (RFW), for a week. To assess the viability and proliferation rate of treated cells, MTT assay was done, and then immunocytochemistry staining Neu N was used to evaluate cell differentiation to neuron. Results showed that EMF decreases the viability and proliferation in treated groups. But in AC group's reduction was significant. Minimum viability and proliferation rate was observed in RHW 400μT group compared with sham. Immunocytochemistry showed that EMF can induce BMSC differentiation into neuron in AC 400μT and RFW 400μT. Evidences of this research support the hypothesis that EMF can induce differentiation of BMSCs to neuron.

  13. Evolution of bulgeless low surface brightness galaxies

    Science.gov (United States)

    Shao, X.; Hammer, F.; Yang, Y. B.; Liang, Y. C.

    Based on the Sloan Digital Sky Survey DR 7, we investigate the environment, morphology, and stellar population of bulgeless low surface-brightness (LSB) galaxies in a volume-limited sample with redshift ranging from 0.024 to 0.04 and M r LSB galaxies have more young stars and are more metal-poor than regular LSB galaxies. These results suggest that the evolution of LSB galaxies may be driven by their dynamics, including mergers rather than by their large-scale environment.

  14. Raman beam combining for laser brightness enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

    2015-10-27

    An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

  15. The radio properties of bright Seyfert galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Bertotti, G. (Centro Interuniversitario Regionale per l' Astrofisica e la Cosmologia (Italy) Centre for Advanced Research in Space Optics (Italy))

    1990-03-01

    The radio properties of a sample of 69 bright spectroscopically selected Seyfert galaxies, which suffers from little bias toward Markarian galaxies with strong UV excess. At variance with most of the earlier results, generally based on galaxy samples which are strongly biased toward the inclusion of Markarian objects, there is no clear evidence of a significant difference in the major radio properties (radio power, radio-to-optical luminosity ratio, radio spectral index and radio size) of type 1 and type 2 Seyferts. The resulting observational scenario appears now to be more consistent than before with the idea that Seyfert 2 galaxies are simply Seyfert 1 obscured objects. 70 refs.

  16. Monitoring of bright blazars with MAGIC telescope

    OpenAIRE

    Hsu, C. C.; Satalecka, K.; Thom, M; Backes, M.; Bernardini, E.; Bonnoli, G.; Galante, N.; Goebel, F; Lindfors, E.; Majumdar, P.; Stamerra, A.; Wagner, R. M.

    2009-01-01

    Blazars, a class of Active Galactic Nuclei (AGN) characterized by a close orientation of their relativistic outflows (jets) towards the line of sight, are a well established extragalactic TeV $\\gamma$-ray emitters. Since 2006, three nearby and TeV bright blazars, Markarian (Mrk) 421, Mrk 501 and 1ES 1959+650, are regularly observed by the MAGIC telescope with single exposures of 30 to 60 minutes. The sensitivity of MAGIC allows to establish a flux level of 30% of the Crab flux for each such o...

  17. Quantum bright soliton in a disorder potential

    OpenAIRE

    Sacha, K.; Delande, D; Zakrzewski, J.

    2009-01-01

    At very low temperature, a quasi-one-dimensional ensemble of atoms with attractive interactions tend to form a bright soliton. When exposed to a sufficiently weak external potential, the shape of the soliton is not modified, but its external motion is affected. We develop in detail the Bogoliubov approach for the problem, treating, in a non-perturbative way, the motion of the center of mass of the soliton. Quantization of this motion allows us to discuss its long time properties. In particula...

  18. Study of the combined action of gamma radiation and static electric fields in human cells

    International Nuclear Information System (INIS)

    The basic principle of radiotherapy is the one of maximizing damage to the tumor, while minimizing it in neighboring health tissues. Several strategies have been worked out aiming at increasing cellular radiosensitivity, and among them is the use of exogenous fields. Our goal in this work is the study in human cells of the effect resulting from the association of irradiation with exposure to exogenous static electric fields. The T47D cell line of breast cancer cells was irradiated with gammas in the 0 - 8 Gy doses range. The corresponding survival curve provided information on the radiosensitivity of this cell line. The rate of cell deaths per Gray in the 0 - 8 Gy range exhibited a maximum at 2 Gy, which corresponds to the most efficient irradiation dose. The viability of this T47D cells exposed to both gamma radiation and 1.250 V/cm static electric field (SEF) was about 12% lower than when only irradiated. The sole exposure of the cells to SEF by 24 and 72 hours didn't induce toxicity. Immunofluorescence runs carried out in irradiated normal MRC5 cell line of human lung fibroblast, without and with exposition to a SEF, have quantified the expression of the y- H2AX histone. The amount of phosphorylated histones was approximately 40% higher after irradiation with 2 Gy plus exposure to a SEF by 1 hour, showing that the electric field negatively interfered in the repairing process of the DNA double strand breaks. The flow cytometry analysis with FACS allowed the investigation of a possible interference of radiation and SEF in the cell distributions among the cellular cycle phases. It was found that in T47D cells treated with 1 and 2 Gy by 24 hours the SEF also negatively interfered in the DNA repairing process, as evidenced by the higher accumulation of cells in the S phase. Therefore, it would be possible to conclude that static and exogenous electric fields are able of negatively interfering in the cellular repair and, presumably, in DNA repair. (author)

  19. Genotoxic Effects of Superconducting Static Magnetic Fields (SMFs) on Wheat (Triticum aestivum) Pollen Mother Cells (PMCs)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Pingping; YIN Ruochun; CHEN Zhiyou; WU Lifang; YU Zengliang

    2007-01-01

    The effects of superconducting static magnetic fields (SMFs) on the pollen mother cells (PMCs) of wheat were investigated in order to evaluate the possible genotoxic effect of such non-ionizing radiation.The seeds of wheat were exposed to static magnetic fields with either different magnetic flux densities (0,1,3,5 and 7 Tesla) for 5 h or different durations (1,3 and 5 h) at a magnetic flux density of 7 Tesla.The seeds were germinated at 23℃ after exposure and the seedlings were transplanted into the field.The PMCs from young wheat ears were taken and slides were made following the conventional method.The genotoxic effect was evaluated in terms of micronucleus (MN),chromosomal bridge,lagging chromosome and fragments in PMCs.Although the exposed groups of a low field intensity (below 5 Tesla) showed no statistically significant difference in the aberration frequency compared with the unexposed control groups and sham exposed groups,a significant increase in the chromosomal bridge,lagging chromosome,triple-polar segregation or micronucleus was observed at a field strength of 5 Tesla or 7 Tesla,respectively.The analysis of dose-effect relationships indicated that the increased frequency of meiotic abnormal cells correlated with the flux density of the magnetic field and duration,but no linear relationship was observed.Such statistically significant differences indicated a potential genotoxic effect of high static magnetic fields above 5 T.

  20. Genotoxic Effects of Superconducting Static Magnetic Fields (SMFs) on Wheat (Triticum aestivum) Pollen Mother Cells (PMCs)

    International Nuclear Information System (INIS)

    The effects of superconducting static magnetic fields (SMFs) on the pollen mother cells (PMCs) of wheat were investigated in order to evaluate the possible genotoxic effect of such non-ionizing radiation. The seeds of wheat were exposed to static magnetic fields with either different magnetic flux densities (0, 1, 3, 5 and 7 Tesla) for 5 h or different durations (1, 3 and 5 h) at a magnetic flux density of 7 Tesla. The seeds were germinated at 23oC after exposure and the seedlings were transplanted into the field. The PMCs from young wheat ears were taken and slides were made following the conventional method. The genotoxic effect was evaluated in terms of micronucleus (MN), chromosomal bridge, lagging chromosome and fragments in PMCs. Although the exposed groups of a low field intensity (below 5 Tesla) showed no statistically significant difference in the aberration frequency compared with the unexposed control groups and sham exposed groups, a significant increase in the chromosomal bridge, lagging chromosome, triple-polar segregation or micronucleus was observed at a field strength of 5 Tesla or 7 Tesla, respectively. The analysis of dose-effect relationships indicated that the increased frequency of meiotic abnormal cells correlated with the flux density of the magnetic field and duration, but no linear relationship was observed. Such statistically significant differences indicated a potential genotoxic effect of high static magnetic fields above 5 T

  1. Genotoxic Effects of Superconducting Static Magnetic Fields (SMFs) on Wheat (Triticum aestivum) Pollen Mother Cells (PMCs)

    Science.gov (United States)

    Zhang, Pingping; Yin, Ruochun; Chen, Zhiyou; Wu, Lifang; Yu, Zengliang

    2007-04-01

    The effects of superconducting static magnetic fields (SMFs) on the pollen mother cells (PMCs) of wheat were investigated in order to evaluate the possible genotoxic effect of such non-ionizing radiation. The seeds of wheat were exposed to static magnetic fields with either different magnetic flux densities (0, 1, 3, 5 and 7 Tesla) for 5 h or different durations (1, 3 and 5 h) at a magnetic flux density of 7 Tesla. The seeds were germinated at 23oC after exposure and the seedlings were transplanted into the field. The PMCs from young wheat ears were taken and slides were made following the conventional method. The genotoxic effect was evaluated in terms of micronucleus (MN), chromosomal bridge, lagging chromosome and fragments in PMCs. Although the exposed groups of a low field intensity (below 5 Tesla) showed no statistically significant difference in the aberration frequency compared with the unexposed control groups and sham exposed groups, a significant increase in the chromosomal bridge, lagging chromosome, triple-polar segregation or micronucleus was observed at a field strength of 5 Tesla or 7 Tesla, respectively. The analysis of dose-effect relationships indicated that the increased frequency of meiotic abnormal cells correlated with the flux density of the magnetic field and duration, but no linear relationship was observed. Such statistically significant differences indicated a potential genotoxic effect of high static magnetic fields above 5 T.

  2. Frequency-Tunable Microwave Field Detection in an Atomic Vapor Cell

    CERN Document Server

    Horsley, Andrew

    2016-01-01

    We use an atomic vapor cell as a frequency tunable microwave field detector operating at frequencies from GHz to tens of GHz. We detect microwave magnetic fields from 2.3 GHz to 26.4 GHz, and measure the amplitude of the sigma+ component of an 18 GHz microwave field. Our proof-of-principle demonstration represents a four orders of magnitude extension of the frequency tunable range of atomic magnetometers from their previous dc to several MHz range. When integrated with a high resolution microwave imaging system, this will allow for the complete reconstruction of the vector components of a microwave magnetic field and the relative phase between them. Potential applications include near-field characterisation of microwave circuitry and devices, and medical microwave sensing and imaging.

  3. How electromagnetic fields can influence adult stem cells: positive and negative impacts.

    Science.gov (United States)

    Maziarz, Aleksandra; Kocan, Beata; Bester, Mariusz; Budzik, Sylwia; Cholewa, Marian; Ochiya, Takahiro; Banas, Agnieszka

    2016-01-01

    The electromagnetic field (EMF) has a great impact on our body. It has been successfully used in physiotherapy for the treatment of bone disorders and osteoarthritis, as well as for cartilage regeneration or pain reduction. Recently, EMFs have also been applied in in vitro experiments on cell/stem cell cultures. Stem cells reside in almost all tissues within the human body, where they exhibit various potential. These cells are of great importance because they control homeostasis, regeneration, and healing. Nevertheless, stem cells when become cancer stem cells, may influence the pathological condition. In this article we review the current knowledge on the effects of EMFs on human adult stem cell biology, such as proliferation, the cell cycle, or differentiation. We present the characteristics of the EMFs used in miscellaneous assays. Most research has so far been performed during osteogenic and chondrogenic differentiation of mesenchymal stem cells. It has been demonstrated that the effects of EMF stimulation depend on the intensity and frequency of the EMF and the time of exposure to it. However, other factors may affect these processes, such as growth factors, reactive oxygen species, and so forth. Exploration of this research area may enhance the development of EMF-based technologies used in medical applications and thereby improve stem cell-based therapy and tissue engineering. PMID:27086866

  4. The microbial cell surface electric field: life in an ion cloud

    Science.gov (United States)

    Yee, N.

    2005-05-01

    Electrical charge on microbial cell surfaces arises from the ionization of proton-active functional groups attached to cell wall polymers. In Gram-positive cell walls, ionizable functional groups are associated with peptidoglycan and secondary polymers such as teichoic or teichuronic acids. Carboxyl functional groups attached to the unlinked peptide crosslinks of peptidoglycan and phosphoryl groups associated with the teichoic acids can deprotonate to form negatively charged surface sites. These anionic functional groups generate charge in the cell wall which results in the formation of an electric field that surrounds the entire cell. The cell surface electric field controls the concentration and spatial distribution of ions and counterions at the cell-water interface, and strongly affects microbe-fluid and microbe-mineral interactions. Recently, we have used potentiometric titration, infrared spectroscopy, electrophoretic mobility, metal sorption experiments to characterize the surface electrical potential properties of the various Gram-positive and Gram-negative bacterial species. Potentiometric titration experiments show that the deprotonation of acidic cell wall functional groups generate surface charge density values typically ranging from 1.1 to 2.2 mol sites/g of bacteria. Spectroscopic measurements have confirmed that the dominant proton-active sites in the cell wall are carboxyl functional groups. Electrophoretic mobility experiments show that the magnitude of the electrostatic surface potential increases with increasing pH, and decreases with increasing ionic strength. Metal sorption experiments conducted with Ca(II), Sr(II) and Ba(II) exhibit strong ionic strength dependence, suggesting that high concentrations of metal ions are electrostatically bound to bacterial cell walls via outer-sphere complexation. We demonstrate that the electrostatic potential effects on ion sorption at the cell-water interface can be quantified using the Donnan model.

  5. Analysis of the influence of the cell geometry, orientation and cell proximity effects on the electric field distribution from direct RF exposure

    Science.gov (United States)

    Sebastián, J. L.; Muñoz, S.; Sancho, M.; Miranda, J. M.

    2001-01-01

    This paper shows the importance of using a cell model with the proper geometry, orientation and internal structure to study possible cellular effects from direct radiofrequency exposure. For this purpose, the electric field intensity is calculated, using the finite element numerical technique, in single- and multilayer spherical, cylindrical and ellipsoidal mammalian cell models exposed to linearly polarized electromagnetic plane waves of frequencies 900 and 2450 MHz. An extensive analysis is performed on the influence that the cell geometry and orientation with respect to the external field have in the value of the electric field induced in the membrane and cytoplasm. We also show the significant role that the cytoplasmic and extracellular bound water layers play in determining the electric field intensity for the cylindrical and ellipsoidal cell models. Finally, a study of the mutual interactions between cells shows that polarizing effects between cells significantly modify the values of field intensity within the cell.

  6. The effect of an external electric field on thermally-deposited thin CdS/CdTe-based solar cells

    Science.gov (United States)

    Wan, Ke Ming; Zhang, Yu Jun; Li, Ping; Wang, Gang; Xiang, Jin; Ding, Bao Fu; Alameh, Kamal; Song, Qun Liang

    2015-11-01

    Conventional and inverted thin CdS/CdTe-based solar cells are fabricated using thermal deposition techniques, and their performance under an external electric field is investigated. Results show that both positive and negative electric fields can change the performance of the developed solar cells and that the latter recover to their initial state after switching the external electric field off. Heat treatment experiments confirm the negligible impact of the temperature on the solar cell performance. Transient photocurrent experiments show that the carrier transfer efficiency is modulated directly by an external electric field. By taking into account the CdS nanodipole, the effect of an external electric field on the solar cell performance can be well explained. The results presented in this paper open the way toward the realization of solar cells through carrier separation by an electric field provided by the CdS nanodipoles rather than the solar cell junction.

  7. Assessment of Automated Analyses of Cell Migration on Flat and Nanostructured Surfaces

    DEFF Research Database (Denmark)

    Gradinaru, Cristian; Lopacinska, Joanna M.; Huth, Johannes;

    2012-01-01

    analysis. The fact that the segmentation routines of such programs are often challenged by nanostructured surfaces makes the question more pertinent. Here we illustrate how it is possible to track cells on bright field microscopy images with image analysis routines implemented in an open-source cell...

  8. Alkali-vapor cell with metal coated windows for efficient application of an electric field

    Science.gov (United States)

    Sarkisyan, D.; Sarkisyan, A. S.; Guéna, J.; Lintz, M.; Bouchiat, M.-A.

    2005-05-01

    We describe the implementation of a cylindrical T-shaped alkali-vapor cell for laser spectroscopy in the presence of a longitudinal electric field. The two windows are used as two electrodes of the high-voltage assembly, which is made possible by a metallic coating which entirely covers the inner and outer sides of the windows except for a central area to let the laser beams in and out of the cell. This allows very efficient application of the electric field, up to 2kV/cm in a rather dense superheated vapor, even when significant photoemission takes place at the windows during pulsed laser irradiation. The body of the cell is made of sapphire or alumina ceramic to prevent large currents resulting from surface conduction observed in cesiated glass cells. The technique used to attach the monocrystalline sapphire windows to the cell body causes minimal stress birefringence in the windows. In addition, reflection losses at the windows can be made very small. The vapor cell operates with no buffer gas and has no magnetic part. The use of this kind of cell has resulted in an improvement of the signal-to-noise ratio in the measurement of parity violation in cesium vapor underway at ENS, Paris. The technique can be applied to other situations where a brazed assembly would give rise to unacceptably large birefringence in the windows.

  9. Coronal bright points associated with minifilament eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Yang, Bo; Yang, Dan, E-mail: hjcsolar@ynao.ac.cn [Also at Graduate School of Chinese Academy of Sciences, Beijing, China. (China)

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 10{sup 9} cm{sup –3}. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  10. Sublimation in bright spots on (1) Ceres.

    Science.gov (United States)

    Nathues, A; Hoffmann, M; Schaefer, M; Le Corre, L; Reddy, V; Platz, T; Cloutis, E A; Christensen, U; Kneissl, T; Li, J-Y; Mengel, K; Schmedemann, N; Schaefer, T; Russell, C T; Applin, D M; Buczkowski, D L; Izawa, M R M; Keller, H U; O'Brien, D P; Pieters, C M; Raymond, C A; Ripken, J; Schenk, P M; Schmidt, B E; Sierks, H; Sykes, M V; Thangjam, G S; Vincent, J-B

    2015-12-10

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense. PMID:26659183

  11. At Bright Band Inside Victoria Crater

    Science.gov (United States)

    2007-01-01

    A layer of light-toned rock exposed inside Victoria Crater in the Meridiani Planum region of Mars appears to mark where the surface was at the time, many millions of years ago, when an impact excavated the crater. NASA's Mars Exploration Rover Opportunity drove to this bright band as the science team's first destination for the rover during investigations inside the crater. Opportunity's left front hazard-identification camera took this image just after the rover finished a drive of 2.25 meters (7 feet, 5 inches) during the rover's 1,305th Martian day, or sol, (Sept. 25, 2007). The rocks beneath the rover and its extended robotic arm are part of the bright band. Victoria Crater has a scalloped shape of alternating alcoves and promontories around the crater's circumference. Opportunity descended into the crater two weeks earlier, within an alcove called 'Duck Bay.' Counterclockwise around the rim, just to the right of the arm in this image, is a promontory called 'Cabo Frio.'

  12. Globe at Night - Sky Brightness Monitoring Network

    Science.gov (United States)

    Cheung, Sze Leung; Pun, Jason Chun Shing; SO, Chu-wing; Shibata, Yukiko; Walker, Constance Elaine; Agata, Hidehiko

    2015-08-01

    The Global at Night - Sky Brightness Monitoring Network (GaN-MN) is an international project for long-term monitoring of night sky conditions around the world. The GaN-MN consists of fixed monitoring stations each equipped with a Sky Quality Meter - Lensed Ethernet (SQM-LE), which is a specialized light sensor for night sky brightness (NSB) measurement. NSB data are continuously collected at high sampling frequency throughout the night, and these data will be instantly made available to the general public to provide a real-time snapshot of the global light pollution condition. A single data collection methodology, including data sampling frequency, data selection criteria, device design and calibration, and schemes for data quality control, was adopted to ensure uniformity in the data collected. This is essential for a systematic and global study of the level of light pollution. The data collected will also provide the scientific backbone in our efforts to contribute to dark sky conservation through education to the general public and policy makers. The GaN-MN project is endorsed by the IAU IYL Executive Committee Working Group as a major Cosmic Light program in the International Year of Light.

  13. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    ZHU ZengWei; ZHU Di; QU NingSong

    2008-01-01

    A new mechanical electrodeposition technology was proposed,and nanocrystal-line nickel deposit with bright and smooth surface was prepared in the bath without any additive agents.Unlike traditional methods,the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing.Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits,pinholes and nodules.Furthermore,comparing with the deposit prepared by tradi-tional methods,the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm.Every diffraction peak's intensity of the deposit was reduced,the preferential orientation degree of (200) decreased and those of (111) and (220) increased.The microhardness notably increased.The magnetic properties were also changed with decreased saturation magnetization and increased coercive force.It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.Key.words:electrodeposition,electroforming,hard particle,nanocrystalline,bright nickel deposits prepared by this technology.

  14. Coronal bright points associated with minifilament eruptions

    International Nuclear Information System (INIS)

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 109 cm–3. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  15. Subjective comparison of brightness preservation methods for local backlight dimming displays

    DEFF Research Database (Denmark)

    Korhonen, Jari; Mantel, Claire; Forchhammer, Søren

    2015-01-01

    Local backlight dimming is a popular technology in high quality Liquid Crystal Displays (LCDs). In those displays, the backlight is composed of contributions from several individually adjustable backlight segments, set at different backlight luminance levels in different parts of the screen......, according to the luma of the target image displayed on LCD. Typically, transmittance of the liquid crystal cells (pixels) located in the regions with dimmed backlight is increased in order to preserve their relative brightness with respect to the pixels located in the regions with bright backlight...... ordering to compare the relevant methods on a real-life LCD with a local backlight dimming capability. In general, our results show that locally adapted brightness preservation methods produce more preferred visual outcome than global methods, but dependency on the content is also observed. Based...

  16. A possible low-level explanation of "temporal dynamics of brightness induction and White's illusion"

    CERN Document Server

    Karmakar, Subhajit

    2009-01-01

    Based upon physiological observation on time dependent orientation selectivity in the cells of macaque's primary visual cortex together with the psychophysical studies on the tuning of orientation detectors in human vision we suggest that time dependence in brightness perception can be accommodated through the time evolution of cortical contribution to the orientation tuning of the ODoG filter responses. A set of Difference of Gaussians functions has been used to mimic the time dependence of orientation tuning. The tuning of orientation preference and its inversion at a later time have been considered in explaining qualitatively the temporal dynamics of brightness perception observed in "Brief presentations reveal the temporal dynamics of brightness induction and White's illusion" for 58 and 82 ms of stimulus exposure.

  17. Beam position monitors for the high brightness lattice

    International Nuclear Information System (INIS)

    Engineering developments associated with the high brightness lattice and the projected change in machine operating parameters will inherently affect the diagnostics systems and devices installed at present in the storage ring. This is particularly true of the beam position monitoring (BPI) system. The new sixteen unit cell lattice with its higher betatron tune values and the limited space available in the redesigned machine straights for fitting standard BPI vessels forces a fundamental re-evaluation of the beam position monitor system. The design aims for the new system are based on accepting the space limitations imposed while still providing the monitor points required to give good radial and vertical closed orbit plots. The locations of BPI's in the redesigned machine straights is illustrated. A description of the new BPI assemblies and their calibration is given. The BPI's use capacitance button type pick-ups; their response is described. (U.K.)

  18. Induction of Cell Death Mechanisms and Apoptosis by Nanosecond Pulsed Electric Fields (nsPEFs

    Directory of Open Access Journals (Sweden)

    Nova M. Sain

    2013-03-01

    Full Text Available Pulse power technology using nanosecond pulsed electric fields (nsPEFs offers a new stimulus to modulate cell functions or induce cell death for cancer cell ablation. New data and a literature review demonstrate fundamental and basic cellular mechanisms when nsPEFs interact with cellular targets. NsPEFs supra-electroporate cells creating large numbers of nanopores in all cell membranes. While nsPEFs have multiple cellular targets, these studies show that nsPEF-induced dissipation of ΔΨm closely parallels deterioration in cell viability. Increases in intracellular Ca2+ alone were not sufficient for cell death; however, cell death depended of the presence of Ca2+. When both events occur, cell death ensues. Further, direct evidence supports the hypothesis that pulse rise-fall times or high frequency components of nsPEFs are important for decreasing ΔΨm and cell viability. Evidence indicates in Jurkat cells that cytochrome c release from mitochondria is caspase-independent indicating an absence of extrinsic apoptosis and that cell death can be caspase-dependent and –independent. The Ca2+ dependence of nsPEF-induced dissipation of ΔΨm suggests that nanoporation of inner mitochondria membranes is less likely and effects on a Ca2+-dependent protein(s or the membrane in which it is embedded are more likely a target for nsPEF-induced cell death. The mitochondria permeability transition pore (mPTP complex is a likely candidate. Data demonstrate that nsPEFs can bypass cancer mutations that evade apoptosis through mechanisms at either the DISC or the apoptosome.

  19. Effects of 60-Hz fields, estradiol and xenoestrogens on human breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Dees, C.; Travis, C. [Oak Ridge National Lab., TN (United States); Garrett, S. [Oak Ridge Institute for Science and Education, Oak Ridge, TN (United States); Henley, D. [Univ. of Tennessee, Knoxville (United States)

    1996-10-01

    If exposure to xenoestrogens or electromagnetic fields (EMFs) such as 60 Hz contributes to the etiology of breast cancer, it is likely that they must stimulate the growth of breast cells, damage genetic material or enhance the effects of other mitogenic or mutagenic agents (co-promotion). Therefore, the ability of xenoestrogens or exposure to 60-Hz fields to stimulate the entry of growth-arrested human breast cancer cells into the cell cycle was determined using cyclin-dependent kinase 2 (Cdk2) activity, synthesis of cyclin D1 and cdc2 activity. Exposure of estrogen receptor-positive MCF-7 or T-47D cells to estrogen and xenoestrogens (DDT and Red No.3) increased Cdk2 and cyclin B1-cdc2 activity and cyclin D1 synthesis. Exposure of breast cancer cells to 12 mG or 1 or 9 G electromagnetic fields at 60 Hz failed to stimulate Cdk2 or cyclin B1-cdc2 activity or cyclin D1 synthesis. Simultaneous co-exposure of cells to 60-Hz fields and chemical promoters did not enhance Cdk2 activation above the levels produced by the chemical promoter alone. Estrogen and xenoestrogens also stimulated binding of the estrogen receptor to the estrogen receptor element but the EMF did not. Phorbol 12-myristate 13-acetate (PMA) induced phosphorylation of p53 and pRb105 in MCF-7 cells, but EMF exposure had no effect. DNA-damaging chemotherapeutic agents and Red Dye No. 3 were found to increase p53 site-specific DNA binding in breast cancer cells, but EMF exposure did not. These studies suggest that estrogen and xenoestrogens stimulate growth-arrested breast cancer cells to enter the growth cycle, but EMF exposure does not. Site-specific p53-DNA binding was increased in MCF-7 cells treated with DNA-damaging agents, but not by EMF exposure. EMF exposure does not appear to act as a promoter or DNA-damaging agent for human breast cancer cells in vitro. 34 refs., 10 figs.

  20. Cell Wall Regeneration by Protoplasts in the Weak Combined Magnetic Field

    Science.gov (United States)

    Nedukha, Olena; Bogatina, Nina; Kordyum, Elizabeth; Ovcharenko, Yu.; Vorobyeva, T.

    2008-06-01

    Role of gravity on growth of high plants has been studied for many years, but many questions on biogenesis of plant cell wall are investigated insufficiently, and require new experiments. We have studied regeneration of cell wall in the fused and separate protoplasts of tobacco and soyabean in the presence of the weak, alternating magnetic field that consisted of frequency of 32 Hz (for Ca2+ ; F=40 μT) or 75 Hz (for Mg2+; F=60 μT) in side μ-metal shield. We discovered that the combined magnetic field that was adjusted to the cyclotron frequency of Ca2+ or Mg2+ is changed the rate of cell wall regeneration. Light and confocal laser microscopy were used for the investigations.

  1. Effects of magnetic field configuration on rf sputtering for CdS/CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A.; Shao, M.; Fischer, A.; Grecu, D.; Jayamaha, U.; Contreras-Puente, G.; Bohn, R.G. [Univ. of Toledo, OH (United States)

    1996-12-31

    The authors report studies of solar cells prepared by rf planar magnetron sputtering in which the films were deposited using magnetic field structures ranging from approximately balanced to strongly unbalanced in the type II configuration. For films grown with the unbalanced configurations, they find much stronger photoluminescence and much better cell performance than for the balanced configuration. The CdTe films show differences in electrical performance depending on magnetic field as well. These effects are interpreted as arising from the enhanced electron and ion bombardment of the film growth interface for the unbalanced magnetrons. Using two unbalanced magnetrons the authors have fabricated an all-rf-sputtered cell with NREL-verified efficiency of 11.6% at air mass 1.5 illumination.

  2. Electric-field-enhanced nutrient consumption in dielectric biomaterials that contain anchorage-dependent cells.

    Science.gov (United States)

    Belfiore, Laurence A; Floren, Michael L; Belfiore, Carol J

    2012-02-01

    This research contribution addresses electric-field stimulation of intra-tissue mass transfer and cell proliferation in viscoelastic biomaterials. The unsteady state reaction-diffusion equation is solved according to the von Kármán-Pohlhausen integral method of boundary layer analysis when nutrient consumption and tissue regeneration occur in response to harmonic electric potential differences across a parallel-plate capacitor in a dielectric-sandwich configuration. The partial differential mass balance with diffusion and electro-kinetic consumption contains the Damköhler (Λ(2)) and Deborah (De) numbers. Zero-field and electric-field-sensitive Damköhler numbers affect nutrient boundary layer growth. Diagonal elements of the 2nd-rank diffusion tensor are enhanced in the presence of weak electric fields, in agreement with the formalism of equilibrium and nonequilibrium thermodynamics. Induced dipole polarization density within viscoelastic biomaterials is calculated via the real and imaginary components of the complex dielectric constant, according to the Debye equation, to quantify electro-kinetic stimulation. Rates of nutrient consumption under zero-field conditions are described by third-order kinetics that include local mass densities of nutrients, oxygen, and attached cells. Thinner nutrient boundary layers are stabilized at shorter dimensionless diffusion times when the zero-field intra-tissue Damköhler number increases above its initial-condition-sensitive critical value [i.e., {Λ(2)(zero-field)}(critical)≥53, see Eq. (23)], such that the biomaterial core is starved of essential ingredients required for successful proliferation. When tissue regeneration occurs above the critical electric-field-sensitive intra-tissue Damköhler number, the electro-kinetic contribution to nutrient consumption cannot be neglected. The critical electric-field-sensitive intra-tissue Damköhler number is proportional to the Deborah number.

  3. BRITE-Constellation: Nanosatellites for precision photometry of bright stars

    Science.gov (United States)

    Weiss, W. W.; Moffat, A. F. J.; Schwarzenberg-Czerny, A.; Koudelka, O. F.; Grant, C. C.; Zee, R. E.; Kuschnig, R.; Mochnacki, St.; Rucinski, S. M.; Matthews, J. M.; Orleański, P.; Pamyatnykh, A. A.; Pigulski, A.; Alves, J.; Guedel, M.; Handler, G.; Wade, G. A.; Scholtz, A. L.; Scholtz

    2014-02-01

    BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, brightness and temperature variations of stars brighter than V ~ 4, with precision and time coverage not possible from the ground. The current mission design consists of three pairs of 7 kg nanosats (hence ``Constellation'') from Austria, Canada and Poland carrying optical telescopes (3 cm aperture) and CCDs. One instrument in each pair is equipped with a blue filter; the other, a red filter. The first two nanosats (funded by Austria) are UniBRITE, designed and built by UTIAS-SFL (University of Toronto Institute for Aerospace Studies-Space Flight Laboratory) and its twin, BRITE-Austria, built by the Technical University Graz (TUG) with support of UTIAS-SFL. They were launched on 25 February 2013 by the Indian Space Agency, under contract to the Canadian Space Agency. Each BRITE instrument has a wide field of view (~ 24 degrees), so up to 15 bright stars can be observed simultaneously in 32 × 32 sub-rasters. Photometry (with reduced precision but thorough time sampling) of additional fainter targets will be possible through on-board data processing. A critical technical element of the BRITE mission is the three-axis attitude control system to stabilize a nanosat with very low inertia. The pointing stability is better than 1.5 arcminutes rms, a significant advance by UTIAS-SFL over any previous nanosatellite. BRITE-Constellation will primarily measure p- and g-mode pulsations to probe the interiors and ages of stars through asteroseismology. The BRITE sample of many of the brightest stars in the night sky is dominated by the most intrinsically luminous stars: massive stars seen at all evolutionary stages, and evolved medium-mass stars at the very end of their nuclear burning phases (cool giants and AGB stars). The Hertzsprung-Russell diagram for stars brighter than mag V=4 from which the BRITE-Constellation sample

  4. Analysis on the design and property of flow field plates of innovative direct methanol fuel cell.

    Science.gov (United States)

    Chang, Ho; Kao, Mu-Jung; Chen, Chih-Hao; Kuo, Chin-Guo; Lee, Kuang-Ying

    2014-10-01

    The paper uses technology of lithography process to etch flow fields on single side of a printed circuit board (PCB), and combines flow field plate with collector plate to make innovative anode flow field plates and cathode flow field plates required in direct methanol fuel cell (DMFC), and meanwhile makes membrane electrode assembly (MEA) and methanol fuel plate. The flow field plates are designed to be in the form of serpentine flow field. The paper measured the assembled DMFC to achieve the overall efficiency of DMFC under the conditions of different screw torques and different concentration, flow rate and temperature of methanol. Experimental results show that when the flow field width of flow field plate is 1 mm, the screw torque is 16 kgf/cm, and the concentration, flow rate and temperature of methanol-water are 1 M, 180 ml/h and 50 degrees C respectively, the prepared DMFC can have better power density of 5.5 mW/cm2, 5.4 mW/cm2, 11.2 mW/cm2 and 11.8 mW/cm2. Besides, the volume of the DMFC designed and assembled by the study is smaller than the generally existing DMFC by 40%. PMID:25942924

  5. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    Directory of Open Access Journals (Sweden)

    Kátia M. M. Eiras

    2005-12-01

    Full Text Available Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC(PODD, O(DC(PODP, OD(PODD, OD(PODP, ODHT(PODD, ODHT(PODP, OA/D(PODD, OA/D(PODP, OAD(PODD and O(ZeD(PO. Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to 90±0.5% ISO. Brightness stability was measured after each bleaching stage of the various sequences andexpressed as brightness loss in % ISO. The results indicate that pulps bleached with sequences ending with a peroxide stage havehigher brightness stability compared to those ending with a chlorine dioxide stage. Pulps bleached with a standard sequence, initiatingwith a (DC stage, show brightness stability similar to that of pulp bleached by an ECF (Elementary chlorine free sequence initiatingwith a regular D0 stage. ECF sequences, initiated with hot stages produce pulps with higher brightness stability than sequencesinitiating with a regular D0 stage. The profile across the bleaching sequences shows a tendency of increased brightness stability inalkaline stages containing peroxide and decreased stability in those stages containing chlorine and/or chlorine dioxide, parallelingpulp carbonyl group content.

  6. Physiological and Molecular Genetic Effects of Time-Varying Electromagnetic Fields on Human Neuronal Cells

    Science.gov (United States)

    Goodwin, Thomas J.

    2003-01-01

    The present investigation details the development of model systems for growing two- and three-dimensional human neural progenitor cells within a culture medium facilitated by a time-varying electromagnetic field (TVEMF). The cells and culture medium are contained within a two- or three-dimensional culture vessel, and the electromagnetic field is emitted from an electrode or coil. These studies further provide methods to promote neural tissue regeneration by means of culturing the neural cells in either configuration. Grown in two dimensions, neuronal cells extended longitudinally, forming tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time-varying electrical current was conducted. In the three-dimensional aspect, exposure to TVEMF resulted in the development of three-dimensional aggregates, which emulated organized neural tissues. In both experimental configurations, the proliferation rate of the TVEMF cells was 2.5 to 4.0 times the rate of the non-waveform cells. Each of the experimental embodiments resulted in similar molecular genetic changes regarding the growth potential of the tissues as measured by gene chip analyses, which measured more than 10,000 human genes simultaneously.

  7. An Alkali-Vapor Cell with Metal Coated Windows for Efficient Application of an Electric Field

    CERN Document Server

    Sarkisyan, D; Guena, J; Lintz, M; Bouchiat, M A; Sarkisyan, David; Gu\\'{e}na, Jocelyne; Lintz, Michel; Bouchiat, Marie-Anne

    2005-01-01

    We describe the implementation of a cylindrical T-shaped alkali-vapor cell for laser spectroscopy in the presence of a longitudinal electric field. The two windows are used as two electrodes of the high-voltage assembly, which is made possible by a metallic coating which entirely covers the inner and outer sides of the windows except for a central area to let the laser beams in and out of the cell. This allows very efficient application of the electric field, up to 2 kV/cm in a rather dense superheated vapor, even when significant photoemission takes place at the windows during pulsed laser irradiation. The body of the cell is made of sapphire or alumina ceramic to prevent large currents resulting from surface conduction observed in cesiated glass cells. The technique used to attach the monocrystalline sapphire windows to the cell body causes minimal stress birefringence in the windows. In addition, reflection losses at the windows can be made very small. The vapor cell operates with no buffer gas and has no ...

  8. Deformation of biological cells in the acoustic field of an oscillating bubble.

    Science.gov (United States)

    Zinin, Pavel V; Allen, John S

    2009-02-01

    In this work we develop a theoretical framework of the interaction of microbubbles with bacteria in the ultrasound field using a shell model of the bacteria, following an approach developed previously [P. V. Zinin, Phys. Rev. E 72, 61907 (2005)]. Within the shell model, the motion of the cell in an ultrasonic field is determined by the motion of three components: the internal viscous fluid, a thin elastic shell, and the surrounding viscous fluid. Several conclusions can be drawn from the modeling of sound interaction with a biological cell: (a) the characteristics of a cell's oscillations in an ultrasonic field are determined both by the elastic properties of the shell the viscosities of all components of the system, (b) for dipole quadrupole oscillations the cell's shell deforms due to a change in the shell area this oscillation depends on the surface area modulus K{A} , (c) the relative change in the area has a maximum at frequency f{K} approximately 1/2pi square root[K{A}(rhoa;{3})] , where a is the cell's radius and rho is its density. It was predicted that deformation of the cell wall at the frequency f{K} is high enough to rupture small bacteria such as E . coli in which the quality factor of natural vibrations is less than 1 (Q1) , the area deformation has a strong peak near a resonance frequency f{K} however, the value of the deformation near the resonance frequency is not high enough to produce sufficient mechanical effect. The theoretical framework developed in this work can be extended for describing the deformation of a biological cell under any arbitrary, external periodic force including radiation forces unduced by acoustical (acoustical levitation) or optical waves (optical tweezers). PMID:19391781

  9. Root responses to soil physical conditions; growth dynamics from field to cell.

    Science.gov (United States)

    Bengough, A Glyn; Bransby, M Fraser; Hans, Joachim; McKenna, Stephen J; Roberts, Tim J; Valentine, Tracy A

    2006-01-01

    Root growth in the field is often slowed by a combination of soil physical stresses, including mechanical impedance, water stress, and oxygen deficiency. The stresses operating may vary continually, depending on the location of the root in the soil profile, the prevailing soil water conditions, and the degree to which the soil has been compacted. The dynamics of root growth responses are considered in this paper, together with the cellular responses that underlie them. Certain root responses facilitate elongation in hard soil, for example, increased sloughing of border cells and exudation from the root cap decreases friction; and thickening of the root relieves stress in front of the root apex and decreases buckling. Whole root systems may also grow preferentially in loose versus dense soil, but this response depends on genotype and the spatial arrangement of loose and compact soil with respect to the main root axes. Decreased root elongation is often accompanied by a decrease in both cell flux and axial cell extension, and recent computer-based models are increasing our understanding of these processes. In the case of mechanical impedance, large changes in cell shape occur, giving rise to shorter fatter cells. There is still uncertainty about many aspects of this response, including the changes in cell walls that control axial versus radial extension, and the degree to which the epidermis, cortex, and stele control root elongation. Optical flow techniques enable tracking of root surfaces with time to yield estimates of two-dimensional velocity fields. It is demonstrated that these techniques can be applied successfully to time-lapse sequences of confocal microscope images of living roots, in order to determine velocity fields and strain rates of groups of cells. In combination with new molecular approaches this provides a promising way of investigating and modelling the mechanisms controlling growth perturbations in response to environmental stresses.

  10. Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

    Science.gov (United States)

    Ruan, Hanxia; Wu, Chaoqun; Liu, Shuliang; Chen, Tao

    2015-12-01

    Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray's Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

  11. Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

    Science.gov (United States)

    Ruan, Hanxia; Wu, Chaoqun; Liu, Shuliang; Chen, Tao

    2016-10-01

    Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray's Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

  12. Effect of weak static magnetic fields on the development of cultured skeletal muscle cells.

    Science.gov (United States)

    Surma, Sergei V; Belostotskaya, Galina B; Shchegolev, Boris F; Stefanov, Vasily E

    2014-12-01

    We studied the effect produced on the development and functional activity of skeletal muscle cells from newborn Wistar rats in primary culture by weak static magnetic fields (WSMF; 60-400 µT) with a high capacity of penetrating the biological media. To reduce the impact of external magnetic fields, cells were cultured at 37 °C in a multilayered shielding chamber with the attenuation coefficient equal to 160. WSMF inside the chamber was created by a circular permanent magnet. We found that the application of WSMF with the magnetic field strength only a few times that of the geomagnetic field can accelerate the development of skeletal muscle cells, resulting in the formation of multinuclear hypertrophied myotubes. WSMF was shown to induce 1.5- to 3.5-fold rise in the concentration of intracellular calcium [Ca(2+)]i due to the release of Ca(2+) from the sarcoplasmic reticulum (SR) through ryanodine receptors (RyR), which increases in the maturation of myotubes. We also found that fully differentiated myotubes at late stages of development were less sensitive to WSMF, manifesting a gradual decrease in the frequency of contractions. However, myotubes at the stage when electromechanical coupling was forming dramatically reduced the frequency of contractions during the first minutes of their exposure to WSMF.

  13. Modelling Solar and Stellar Brightness Variabilities

    Science.gov (United States)

    Yeo, K. L.; Shapiro, A. I.; Krivova, N. A.; Solanki, S. K.

    2016-04-01

    Total and spectral solar irradiance, TSI and SSI, have been measured from space since 1978. This is accompanied by the development of models aimed at replicating the observed variability by relating it to solar surface magnetism. Despite significant progress, there remains persisting controversy over the secular change and the wavelength-dependence of the variation with impact on our understanding of the Sun's influence on the Earth's climate. We highlight the recent progress in TSI and SSI modelling with SATIRE. Brightness variations have also been observed for Sun-like stars. Their analysis can profit from knowledge of the solar case and provide additional constraints for solar modelling. We discuss the recent effort to extend SATIRE to Sun-like stars.

  14. Hybrid quantum repeater using bright coherent light.

    Science.gov (United States)

    van Loock, P; Ladd, T D; Sanaka, K; Yamaguchi, F; Nemoto, Kae; Munro, W J; Yamamoto, Y

    2006-06-23

    We describe a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent-light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and postselection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. Finally, the entanglement is stored in a nuclear-spin-based quantum memory. With our system, qubit-communication rates approaching 100 Hz over 1280 km with fidelities near 99% are possible for reasonable local gate errors.

  15. Brightness temperature for 166 radio sources

    Institute of Scientific and Technical Information of China (English)

    Jun-Hui Fan; Yong Huang; Yu-Hai Yuan; Jiang-He Yang; Yi Liu; Jun Tao; Ying Gao; Tong-Xu Hua; Rui-Guang Lin; Jiang-Shui Zhang; Jing-Yi Zhang; Yi-Ping Qin

    2009-01-01

    Using the database of the University of Michigan Radio Astronomy Observatory (UMRAO) at three radio frequencies (4.8, 8 and 14.5 GHz), we determined the short-term variability timescales for 166 radio sources. The timescales are 0.15d (2007+777) to 176.17d (0528-250) with an average timescale of △tobs=17.1±16.5d for the whole sample. The timescales are used to calculate the brightness temperatures, TB. The value of log TB is in the range of log TB = 10.47 to 19.06 K. In addition, we also estimated the boosting factor for the sources. The correlation between the polarization and the Doppler factor is also discussed.

  16. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  17. Considerations for high-brightness electron sources

    International Nuclear Information System (INIS)

    Particle accelerators are now used in many areas of physics research and in industrial and medical applications. New uses are being studied to address major societal needs in energy production, materials research, generation of intense beams of radiation at optical and suboptical wavelengths, treatment of various kinds of waste, and so on. Many of these modern applications require a high intensity beam at the desired energy, along with a very good beam quality in terms of the beam confinement, aiming, or focusing. Considerations for ion and electron accelerators are often different, but there are also many commonalties, and in fact, techniques derived for one should perhaps more often be considered for the other as well. We discuss some aspects of high-brightness electron sources here from that point of view. 6 refs

  18. Dark Skies, Bright Kids Year 7

    Science.gov (United States)

    Bittle, Lauren E.; Johnson, Kelsey E.; Borish, H. Jacob; Burkhardt, Andrew; Firebaugh, Ariel; Hancock, Danielle; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; Prager, Brian; Pryal, Matthew; Sokal, Kimberly R.; Troup, Nicholas William; Wenger, Trey

    2016-01-01

    We present updates from our seventh year of operation including new club content, continued assessments, and our fifth annual Star Party. Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.

  19. On high brightness temperature of pulsar giant pulses

    CERN Document Server

    Kontorovich, V M

    2009-01-01

    Giant pulses observed in a number of pulsars show a record brightness temperature which corresponds to the high energy density of 10^15 erg/cm^3. Comparable densities of energy in the radio-frequency region are attainable in a cavity-resonator being the pulsar internal vacuum gap. Energy emission through the breaks accidentally appearing in the magnetosphere of open field lines corresponds to the giant pulses. The emitted energy is defined by the break area, which causes a power dependence of break occurrence probability. The observed localization of giant pulses as to the average pulse is explained by radiation through a waveguide near the magnetic axis or through a slot on the border of the open field lines. Separate discharges may be superimposed on the radiation through the breaks forming the fine structure of giant pulses with duration up to some nanoseconds. Coulomb repulsion of particles in the puncture spark in the gap leads to spark rotation around its axis in the crossed fields, which provokes the a...

  20. Dynamic changes of [Ca2+]i in cerebellar granule cells exposed to pulsed electric fields

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Intracellular free Ca2+ concentration ([Ca2+]i) in embryonic chick cerebellar granule cells loaded with fluo-3/AM and exposed to a single pulsed electric field was investigated using a confocal laser scanning microscope and fluorescent microscope equipped with CCD video imaging system.The results showed that [Ca2+]i increased immediately and rose to the peak rapidly as the cells exposed to a single pulsed electric field.The amplitude and rate of the increases of [Ca2+]i depend on the intensity of external electric field.In the presence of Ca2+ chelant EGTA or Ca2+ channels blocker La3+ in the pulsation solutions,the increase of [Ca2+]i was still observable.It was also observed that [Ca2+]i of different intracellular areas in the cell elevated simultaneously while the peak of the increase of [Ca2+]i in the poles of the cell preceded to the peak in its somata and recovered to a plateau within a short time.

  1. Dynamic changes of [Ca2+]i in cerebellar granule cells exposed to pulsed electric fields

    Institute of Scientific and Technical Information of China (English)

    陈雅; 王彦; 孙彤; 张锦珠; 景向红; 李瑞午

    2000-01-01

    Intracellular free Ca2+ concentration ([Ca2+]i) in embryonic chick cerebellar granule cells loaded with fluo-3/AM and exposed to a single pulsed electric field was investigated using a confocal laser scanning microscope and fluorescent microscope equipped with CCD video imaging system. The results showed that [Ca2+]i increased immediately and rose to the peak rapidly as the cells exposed to a single pulsed electric field. The amplitude and rate of the increases of [Ca2+]i depend on the intensity of external electric field. In the presence of Ca2+ chelant EGTA or Ca2+ channels blocker La3+ in the pulsation solutions, the increase of [Ca2+]i was still observable. It was also observed that [Ca2+]i of different intracellular areas in the cell elevated simultaneously while the peak of the increase of [Ca2+]i in the poles of the cell preceded to the peak in its somata and recovered to a plateau within a short time.

  2. The Effect of 217 Hz Magnetic Field of Cell Phone with Different Intensities on Apoptosis of Normal and Cancerous Cells Treated with Chemotherapy Drug

    Directory of Open Access Journals (Sweden)

    Mahsa Mansourian

    2012-03-01

    Full Text Available Background: According to the increasing development of home and business electronic equipment in today's world, the biological effects of ELF magnetic fields have been studied at two molecular-cellular and animal- human levels. Considering the therapeutic viewpoint of this study regarding the effects of low-frequency fields of mobile phone, the effect of acute exposure to this field on chemotherapy will be studied.Materials and Methods: In this experimental study, based on measurement of the intensity of the magnetic fields from mobile phones in another research, flux densities of magnetic field of 159.44, 93.25 and 120µ tesla with frequency of 217Hz was generated in magnetic field generator system, and the apoptosis level in K562 cancer cells and healthy cells of lymphocytes was assessed after exposure to field using flow cytometry method. This evaluation method was also performed for the cells treated with bleomycin after exposure to this field.Results: 217 Hz magnetic field exposure significantly increases the rate of apoptosis percentage (p > 0.05 in K562 cancer cells and in two intensities of 120 and 159.44µ tesla compared to the control group, but such effect is not observed in lymphocyte cells. Bleomycin-induced apoptosis percentage following exposure to the mentioned magnetic field shows no significant difference compared to the group of treatment with drug and without field exposure. This lack of significant difference is observed between the groups of drug after field exposure and field alone as well as between groups exposed to field and groups treated with bleomycin.Conclusion: Study results showed that 217 Hz magnetic field of mobile phone can induce apoptosis on cancer cells, but it has no effect on healthy cells. Thus, in order to use mobile phone as an effective factor in their treatment, some studies should be conducted at animal-human level.

  3. Exploration of molecular pathways mediating electric field-directed Schwann cell migration by RNA-seq.

    Science.gov (United States)

    Yao, Li; Li, Yongchao; Knapp, Jennifer; Smith, Peter

    2015-07-01

    In peripheral nervous systems, Schwann cells wrap around axons of motor and sensory neurons to form the myelin sheath. Following spinal cord injury, Schwann cells regenerate and migrate to the lesion and are involved in the spinal cord regeneration process. Transplantation of Schwann cells into injured neural tissue results in enhanced spinal axonal regeneration. Effective directional migration of Schwann cells is critical in the neural regeneration process. In this study, we report that Schwann cells migrate anodally in an applied electric field (EF). The directedness and displacement of anodal migration increased significantly when the strength of the EF increased from 50 mV/mm to 200 mV/mm. The EF did not significantly affect the cell migration speed. To explore the genes and signaling pathways that regulate cell migration in EFs, we performed a comparative analysis of differential gene expression between cells stimulated with an EF (100 mV/mm) and those without using next-generation RNA sequencing, verified by RT-qPCR. Based on the cut-off criteria (FC > 1.2, q < 0.05), we identified 1,045 up-regulated and 1,636 down-regulated genes in control cells versus EF-stimulated cells. A Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis found that compared to the control group, 21 pathways are down-regulated, while 10 pathways are up-regulated. Differentially expressed genes participate in multiple cellular signaling pathways involved in the regulation of cell migration, including pathways of regulation of actin cytoskeleton, focal adhesion, and PI3K-Akt. PMID:25557037

  4. The three-dimensional structures of X-ray bright points

    Science.gov (United States)

    Parnell, C. E.; Priest, E. R.; Golub, L.

    1994-01-01

    Recently, the Convergin Flux Model has been proposed for X-ray bright points and cancelling magnetic features. The aim of this piece of work is to try and model theoretically specific X-ray bright points in the framework of the Converging Flux Model. The observational data used includes a magnetogram showing the normal component of the magnetic field at the photosphere and a high-resolution soft X-ray image from NIXT showing the brightenings in the lower solar corona. By approximating the flux concentrations in the magnetograms with poles of the appropriate sign and sense, the overlying three-dimensional potential field structure is calculated. Deduction of plausible motions of the flux sources are made which produce brightenings of the observed shape due to reconnection between neighbouring flux regions. Also the three-dimensional separatrix and separator structure and the way the magnetic field lines reconnect in three dimensions is deduced.

  5. Dynamic effects and applications for nanosecond pulsed electric fields in cells and tissues

    Science.gov (United States)

    Beebe, Stephen J.; Blackmore, Peter F.; Hall, Emily; White, Jody A.; Willis, Lauren K.; Fauntleroy, Laura; Kolb, Juergen F.; Schoenbach, Karl H.

    2005-04-01

    Nanosecond, high intensity pulsed electric fields [nsPEFs] that are below the plasma membrane [PM] charging time constant have decreasing effects on the PM and increasing effects on intracellular structures and functions as the pulse duration decreases. When human cell suspensions were exposed to nsPEFs where the electric fields were sufficiently intense [10-300ns, adipocytes including decreased cell size and number, caspase activation, DNA fragmentation, and/or cytochrome c release into the cytoplasm. Phosphatidylserine externalization was observed as a biological response to nsPEFs in 3T3-L1 preadipocytes and p53-wildtype and -null human colon carcinoma cells. B10.2 mouse fibrosarcoma tumors that were exposed to nsPEFs ex vivo and in vivo exhibited DNA fragmentation, elevated caspase activity, and reduced size and weight compared to contralateral sham-treated control tumors. When nsPEF conditions were below thresholds for apoptosis and classical PM electroporation, non-apoptotic responses were observed similar to those initiated through PM purinergic receptors in HL-60 cells and thrombin in human platelets. These included Ca2+ mobilization from intracellular stores [endoplasmic reticulum] and subsequently through store-operated Ca2+ channels in the PM. In addition, platelet activation measured as aggregation responses were observed in human platelets. Finally, when nsPEF conditions followed classical electroporation-mediated transfection, the expression intensity and number of GFP-expressing cells were enhanced above cells exposed to electroporation conditions alone. These studies demonstrate that application of nsPEFs to cells or tissues can modulate cell-signaling mechanisms with possible applications as a new basic science tool, cancer treatment, wound healing, and gene therapy.

  6. A 21-cm line study of NGC 5963, an SC galaxy with a low-surface brightness disk

    Science.gov (United States)

    Bosma, A.; Athanassoula, E.; van der Hulst, J. M.

    1988-06-01

    Results are presented from a detailed 21-cm line study of the Sc galaxy NGC 5963. The extent of the H I emission is found to be roughly coincident with the optical image, the latter being of much lower surface brightness than normal for Sc galaxies. The velocity field shows little deviation from axial symmetry, and the derived rotation curve is typical for Sc galaxies about twice as bright as NGC 5963. A composite mass model is presented using the observed light distribution to calculate a rotation curve for the luminous part of the galaxy (assuming a constant M/L-ratio with radius); this calculated rotation curve is compared to the observed one to derive a rotation law for a dark halo. Comparison with Sc galaxies having normal disk surface brightnesses suggests that the halo in NGC 5963 is more concentrated than in normal Scs with similar rotation curves. The origin of the low surface brightness of the disk is discussed.

  7. Variability, Brightness Temperature, Superluminal Motion, Doppler Boosting, and Related Issues

    CERN Document Server

    Kellermann, K I

    2003-01-01

    We review the observations of rapid flux density variations in compact radio sources, and discuss the inverse Compton limit to the maximum brightness temperature of incoherent synchrotron sources in comparison with recent VLBA observations. The apparent agreement of the theoretical brightness temperature limit due to inverse Compton cooling and the brightness temperatures observed by early VLBI observations appears to have been fortuitous. VLBA observations have greatly improved the quality of the data, but many of the early issues remain unresolved.

  8. AC electric field induced dipole-based on-chip 3D cell rotation.

    Science.gov (United States)

    Benhal, Prateek; Chase, J Geoffrey; Gaynor, Paul; Oback, Björn; Wang, Wenhui

    2014-08-01

    The precise rotation of suspended cells is one of the many fundamental manipulations used in a wide range of biotechnological applications such as cell injection and enucleation in nuclear transfer (NT) cloning. Noticeably scarce among the existing rotation techniques is the three-dimensional (3D) rotation of cells on a single chip. Here we present an alternating current (ac) induced electric field-based biochip platform, which has an open-top sub-mm square chamber enclosed by four sidewall electrodes and two bottom electrodes, to achieve rotation about the two axes, thus 3D cell rotation. By applying an ac potential to the four sidewall electrodes, an in-plane (yaw) rotating electric field is generated and in-plane rotation is achieved. Similarly, by applying an ac potential to two opposite sidewall electrodes and the two bottom electrodes, an out-of-plane (pitch) rotating electric field is generated and rolling rotation is achieved. As a prompt proof-of-concept, bottom electrodes were constructed with transparent indium tin oxide (ITO) using the standard lift-off process and the sidewall electrodes were constructed using a low-cost micro-milling process and then assembled to form the chip. Through experiments, we demonstrate rotation of bovine oocytes of ~120 μm diameter about two axes, with the capability of controlling the rotation direction and the rate for each axis through control of the ac potential amplitude, frequency, and phase shift, and cell medium conductivity. The maximum observed rotation rate reached nearly 140° s⁻¹, while a consistent rotation rate reached up to 40° s⁻¹. Rotation rate spectra for zona pellucida-intact and zona pellucida-free oocytes were further compared and found to have no effective difference. This simple, transparent, cheap-to-manufacture, and open-top platform allows additional functional modules to be integrated to become a more powerful cell manipulation system.

  9. A bright neutron source driven by relativistic transparency of solids

    Science.gov (United States)

    Roth, M.; Jung, D.; Falk, K.; Guler, N.; Deppert, O.; Devlin, M.; Favalli, A.; Fernandez, J.; Gautier, D. C.; Geissel, M.; Haight, R.; Hamilton, C. E.; Hegelich, B. M.; Johnson, R. P.; Kleinschmidt, A.; Merrill, F.; Schaumann, G.; Schoenberg, K.; Schollmeier, M.; Shimada, T.; Taddeucci, T.; Tybo, J. L.; Wagner, F.; Wender, S. A.; Wilde, C. H.; Wurden, G. A.

    2016-03-01

    Neutrons are a unique tool to alter and diagnose material properties and excite nuclear reactions with a large field of applications. It has been stated over the last years, that there is a growing need for intense, pulsed neutron sources, either fast or moderated neutrons for the scientific community. Accelerator based spallation sources provide unprecedented neutron fluxes, but could be complemented by novel sources with higher peak brightness that are more compact. Lasers offer the prospect of generating a very compact neutron source of high peak brightness that could be linked to other facilities more easily. We present experimental results on the first short pulse laser driven neutron source powerful enough for applications in radiography. For the first time an acceleration mechanism (BOA) based on the concept of relativistic transparency has been used to generate neutrons. This mechanism not only provides much higher particle energies, but also accelerated the entire target volume, thereby circumventing the need for complicated target treatment and no longer limited to protons as an intense ion source. As a consequence we have demonstrated a new record in laser-neutron production, not only in numbers, but also in energy and directionality based on an intense deuteron beam. The beam contained, for the first time, neutrons with energies in excess of 100 MeV and showed pronounced directionality, which makes then extremely useful for a variety of applications. The results also address a larger community as it paves the way to use short pulse lasers as a neutron source. They can open up neutron research to a broad academic community including material science, biology, medicine and high energy density physics as laser systems become more easily available to universities and therefore can complement large scale facilities like reactors or particle accelerators. We believe that this has the potential to increase the user community for neutron research largely.

  10. Human embryonic and induced pluripotent stem cell research trends: complementation and diversification of the field.

    Science.gov (United States)

    Kobold, Sabine; Guhr, Anke; Kurtz, Andreas; Löser, Peter

    2015-05-12

    Research in human induced pluripotent stem cells (hiPSCs) is rapidly developing and there are expectations that this research may obviate the need to use human embryonic stem cells (hESCs), the ethics of which has been a subject of controversy for more than 15 years. In this study, we investigated approximately 3,400 original research papers that reported an experimental use of these types of human pluripotent stem cells (hPSCs) and were published from 2008 to 2013. We found that research into both cell types was conducted independently and further expanded, accompanied by a growing intersection of both research fields. Moreover, an in-depth analysis of papers that reported the use of both cell types indicates that hESCs are still being used as a "gold standard," but in a declining proportion of publications. Instead, the expanding research field is diversifying and hESC and hiPSC lines are increasingly being used in more independent research and application areas.

  11. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    OpenAIRE

    Kátia M. M. Eiras; Jorge Luiz Colodette; Ana Márcia M. L. Carvalho

    2005-01-01

    Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC)(PO)DD, O(DC)(PO)DP, OD(PO)DD, OD(PO)DP, ODHT(PO)DD, ODHT(PO)DP, OA/D(PO)DD, OA/D(PO)DP, OAD(PO)DD and O(Ze)D(PO). Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to...

  12. Switching Characteristics of Phase Change Memory Cell Integrated with Metal-Oxide Semiconductor Field Effect Transistor

    Institute of Scientific and Technical Information of China (English)

    XU Cheng; CHEN Bomy; LIU Bo; CHEN Yi-Feng; LIANG Shuang; SONG Zhi-Tang; FENG Song-Lin; WAN Xu-Dong; YANG Zuo-Ya; XIE Joseph

    2008-01-01

    A Ge2Sb2Te5 based phase change memory device cell integrated with metal-oxide semiconductor field effect transistor (MOSFET) is fabricated using standard 0.18 μm complementary metal-oxide semiconductor process technology.It shows steady switching characteristics in the dc current-voltage measurement.The phase changing phenomenon from crystalline state to amorphous state with a voltage pulse altitude of 2.0 V and pulse width of 50 ns is also obtained.These results show the feasibility of integrating phase change memory cell with MOSFET.

  13. Signaling networks and cell motility: a computational approach using a phase field description.

    Science.gov (United States)

    Marth, Wieland; Voigt, Axel

    2014-07-01

    The processes of protrusion and retraction during cell movement are driven by the turnover and reorganization of the actin cytoskeleton. Within a reaction-diffusion model which combines processes along the cell membrane with processes within the cytoplasm a Turing type instability is used to form the necessary polarity to distinguish between cell front and rear and to initiate the formation of different organizational arrays within the cytoplasm leading to protrusion and retraction. A simplified biochemical network model for the activation of GTPase which accounts for the different dimensionality of the cell membrane and the cytoplasm is used for this purpose and combined with a classical Helfrich type model to account for bending and stiffness effects of the cell membrane. In addition streaming within the cytoplasm and the extracellular matrix is taken into account. Combining these phenomena allows to simulate the dynamics of cells and to reproduce the primary phenomenology of cell motility. The coupled model is formulated within a phase field approach and solved using adaptive finite elements. PMID:23835784

  14. Investigating the impact of electromagnetic fields on human cells: A thermodynamic perspective

    Science.gov (United States)

    Lucia, Umberto; Ponzetto, Antonio; Deisboeck, Thomas S.

    2016-02-01

    The consequences of the interactions of electromagnetic waves, as used in conventional MRI technology, with human cells are not fully understood. To analyze these interactions, a novel thermodynamic approach is presented that is based on the relationship between electromagnetic and thermodynamic quantities. The theoretical results indicate that the waves' impact is largest at high magnetic field strengths and at low frequencies. This is the first step towards a clinically useful framework to quantitatively assess MRI impact including a potential trade-off between the desired increase in spatial resolution that higher magnetic field strengths yield for diagnostic purposes and the danger this may pose for cell membranes, and by extension, for the tissues investigated.

  15. Two beam energy exchange in hybrid liquid crystal cells with photorefractive field controlled boundary conditions

    Science.gov (United States)

    Reshetnyak, V. Yu.; Pinkevych, I. P.; Subota, S. I.; Evans, D. R.

    2016-09-01

    We develop a theory describing energy gain when two light beams intersect in a hybrid nematic liquid crystal (LC) cell with photorefractive crystalline substrates. A periodic space-charge field induced by interfering light beams in the photorefractive substrates penetrates into the LC layer and reorients the director. We account for two main mechanisms of the LC director reorientation: the interaction of the photorefractive field with the LC flexopolarization and the director easy axis at the cell boundaries. It is shown that the resulting director grating is a sum of two in-phase gratings: the flexoelectric effect driven grating and the boundary-driven grating. Each light beam diffracts from the induced gratings leading to an energy exchange between beams. We evaluate the signal beam gain coefficient and analyze its dependence on the director anchoring energy and the magnitude of the director easy axis modulation.

  16. Evidence of magnetic field switch-off in Particle In Cell simulations of collisionless magnetic reconnection with guide field

    Science.gov (United States)

    Innocenti, M. E.; Goldman, M. V.; Newman, D. L.; Markidis, S.; Lapenta, G.

    2015-12-01

    The long term evolution of large domain Particle In Cell simulations of collisionless magnetic reconnection is investigated following observations that show two possible outcomes for collisionless reconnection: towards a Petschek-like configuration (Gosling 2007) or towards multiple X points (Eriksson et al. 2014). In the simulations presented here and described in [Innocenti2015*], a mixed scenario develops. At earlier time, plasmoids are emitted, disrupting the formation of Petschek-like structures. Later, an almost stationary monster plasmoid forms, preventing the emission of other plasmoids. A situation reminding of Petschek's switch-off then ensues. Switch-off is obtained through a slow shock / rotational discontinuity (SS/RD) compound structure, with the rotation discontinuity downstreamthe slow shock. Two external slow shocks located in correspondence of the separatrices reduce the in plane tangential component of the magnetic field, but not to zero. Two transitions reminding of rotational discontinuities in the internal part of the exhausts then perform the final switch-off. Both the slow shocks and the rotational discontinuities are characterized as such through the analysis of their Rankine-Hugoniot jump conditions. A moderate guide field is used to suppress the development of the firehose instability in the exhaust that prevented switch off in [Liu2012]. Compound SS/RD structures, with the RD located downstream the SS, have been observed in both the solar wind and the magnetosphere in Wind and Geotail data respectively [Whang1998, Whang2004]. Ion trajectiories across the SS/RD structure are followed and the kinetic origin of the SS/RD structure is investigated. * Innocenti, Goldman, Newman, Markidis, Lapenta, Evidence of magnetic field switch-off in collisionless magnetic reconnection, accepted in Astrophysical Journal Letters, 2015 Acknowledgements: NERSC, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of

  17. Study of the selective effect on cells induced by nanosecond pulsed electric field with the resistor-capacitor circuit model

    Institute of Scientific and Technical Information of China (English)

    Xu Fei; Xiao Dengming; Li Zhaozhi

    2009-01-01

    A resistor-capacitor (RC) circuit model is proposed to study the effect of nanosecond pulsed electric field on cells according to the structure and electrical parameters of cells. After a nanosecond step field has been applied, the variation of voltages across cytomembrane and mitochondria membrane both in normal and in malignant cells are studied with this model. The time for selectively targeting the mitochondria membrane and malignant cell can be evaluated much easily with curves that show the variation of voltage across each membrane with time. Ramp field is the typical field applied in electrobiology. The voltages across each membrane induced by ramp field are analyzed with this model. To selectively target the mitochondria membrane, proper range of ramp slope is needed. It is relatively difficult to decide the range of a slope to selectively affect the malignant cell. Under some conditions, such a range even does not exist.

  18. Activation of Schwann cells in vitro by magnetic nanocomposites via applied magnetic field

    Directory of Open Access Journals (Sweden)

    Liu Z

    2014-12-01

    Full Text Available Zhongyang Liu,1,* Liangliang Huang,1,* Liang Liu,1,* Beier Luo,2,* Miaomiao Liang,3 Zhen Sun,1 Shu Zhu,1 Xin Quan,1 Yafeng Yang,1 Teng Ma,1 Jinghui Huang,1 Zhuojing Luo1 1Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi’an, 2Department of Orthopaedics, Changhai Hospital, Second Military Medical University, Shanghai, 3Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi’an, People’s Republic of China *These authors contributed equally to this work Abstract: Schwann cells (SCs are attractive seed cells in neural tissue engineering, but their application is limited by attenuated biological activities and impaired functions with aging. Therefore, it is important to explore an approach to enhance the viability and biological properties of SCs. In the present study, a magnetic composite made of magnetically responsive magnetic nanoparticles (MNPs and a biodegradable chitosan–glycerophosphate polymer were prepared and characterized. It was further explored whether such magnetic nanocomposites via applied magnetic fields would regulate SC biological activities. The magnetization of the magnetic nanocomposite was measured by a vibrating sample magnetometer. The compositional characterization of the magnetic nanocomposite was examined by Fourier-transform infrared and X-ray diffraction. The tolerance of SCs to the magnetic fields was tested by flow-cytometry assay. The proliferation of cells was examined by a 5-ethynyl-2-deoxyuridine-labeling assay, a PrestoBlue assay, and a Live/Dead assay. Messenger ribonucleic acid of BDNF, GDNF, NT-3, and VEGF in SCs was assayed by quantitative real-time polymerase chain reaction. The amount of BDNF, GDNF, NT-3, and VEGF secreted from SCs was determined by enzyme-linked immunosorbent assay. It was found that magnetic nanocomposites containing 10% MNPs showed a cross-section diameter of 32.33±1.81 µm, porosity of 80.41%±0.72%, and

  19. 60 Hz electric field changes the membrane potential during burst phase in pancreatic β-cells: in silico analysis.

    Science.gov (United States)

    Neves, Gesilda F; Silva, José R F; Moraes, Renato B; Fernandes, Thiago S; Tenorio, Bruno M; Nogueira, Romildo A

    2014-06-01

    The production, distribution and use of electricity can generate low frequency electric and magnetic fields (50-60 Hz). Considering that some studies showed adverse effects on pancreatic β-cells exposed to these fields; the present study aimed to analyze the effects of 60 Hz electric fields on membrane potential during the silent and burst phases in pancreatic β-cells using a mathematical model. Sinusoidal 60 Hz electric fields with amplitude ranging from 0.5 to 4 mV were applied on pancreatic β-cells model. The sinusoidal electric field changed burst duration, inter-burst intervals (silent phase) and spike sizes. The parameters above presented dose-dependent response with the voltage amplitude applied. In conclusion, theoretical analyses showed that a 60 Hz electric field with low amplitudes changes the membrane potential in pancreatic β-cells.

  20. Cutaneous papilloma and squamous cell carcinoma therapy utilizing nanosecond pulsed electric fields (nsPEF.

    Directory of Open Access Journals (Sweden)

    Dong Yin

    Full Text Available Nanosecond pulsed electric fields (nsPEF induce apoptotic pathways in human cancer cells. The potential therapeutic effective of nsPEF has been reported in cell lines and in xenograft animal tumor model. The present study investigated the ability of nsPEF to cause cancer cell death in vivo using carcinogen-induced animal tumor model, and the pulse duration of nsPEF was only 7 and 14 nano second (ns. An nsPEF generator as a prototype medical device was used in our studies, which is capable of delivering 7-30 nanosecond pulses at various programmable amplitudes and frequencies. Seven cutaneous squamous cell carcinoma cell lines and five other types of cancer cell lines were used to detect the effect of nsPEF in vitro. Rate of cell death in these 12 different cancer cell lines was dependent on nsPEF voltage and pulse number. To examine the effect of nsPEF in vivo, carcinogen-induced cutaneous papillomas and squamous cell carcinomas in mice were exposed to nsPEF with three pulse numbers (50, 200, and 400 pulses, two nominal electric fields (40 KV/cm and 31 KV/cm, and two pulse durations (7 ns and 14 ns. Carcinogen-induced cutaneous papillomas and squamous carcinomas were eliminated efficiently using one treatment of nsPEF with 14 ns duration pulses (33/39 = 85%, and all remaining lesions were eliminated after a 2nd treatment (6/39 = 15%. 13.5% of carcinogen-induced tumors (5 of 37 were eliminated using 7 ns duration pulses after one treatment of nsPEF. Associated with tumor lysis, expression of the anti-apoptotic proteins Bcl-xl and Bcl-2 were markedly reduced and apoptosis increased (TUNEL assay after nsPEF treatment. nsPEF efficiently causes cell death in vitro and removes papillomas and squamous cell carcinoma in vivo from skin of mice. nsPEF has the therapeutic potential to remove human squamous carcinoma.

  1. Advances in a Rapidly Emerging Field of Hair Follicle Stem Cell Research

    OpenAIRE

    Bukvić Mokos, Zrinka; Lazić Mosler, Elvira

    2014-01-01

    Human skin maintains the ability to regenerate during adulthood, as it constantly renews itself throughout adult life, and the hair follicle (HF) undergoes a perpetual cycle of growth and degeneration. The study of stem cells (SCs) in the epidermis and skin tissue engineering is a rapidly emerging field, where advances have been made in both basic and clinical research. Advances in basic science include the ability to assay SCs of the epidermis in vivo, identification of an independent interf...

  2. Effect of piezoelectric field on carrier dynamics in InGaN-based solar cells

    Science.gov (United States)

    Lee, Seunga; Honda, Yoshio; Amano, Hiroshi

    2016-01-01

    To understand the effect of piezoelectric fields on carrier dynamics, we numerically investigated a simple p-GaN/i-\\text{I}{{\\text{n}}x}\\text{G}{{\\text{a}}1-x}\\text{N} /n-GaN solar cell structure. A reliable simulation model was obtained by comparing the experimental and simulated results in advance. The same p-i-n InGaN structures were re-simulated with and without the piezoelectric field effect, as spontaneous polarization remained unchanged. The sample with the piezoelectric field effect showed higher short current density ({{J}\\text{sc}} ), a staircase-like feature in its I-V curve, and higher open circuit voltage ({{V}\\text{oc}} ) with a lower fill factor (F.F.) and reduced conversion efficiency (C.E.) than the sample with no piezoelectric fields. In addition, with increasing In fraction (x), the {{V}\\text{oc}} value gradually increased while the {{J}\\text{sc}} value significantly decreased, correspondingly leading to a reduction in C.E. and F.F. values of the structure with the piezoelectric field effect. To solve the current loss problem, we applied various piezoelectric field elimination techniques to the simulated structures.

  3. Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host Stars

    CERN Document Server

    Bastien, Fabienne A; Pepper, Joshua

    2014-01-01

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, logg. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure logg to a high accuracy of ~0.1-0.2 dex (Bastien et al. 2013). Here, we use flicker measurements of 289 bright (Kepmag<13) candidate planet-hosting stars with Teff=4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, an astrophysical bias exists that contaminates the stellar sample with evolved stars: nearly 50%...

  4. Extremely Low Frequency Magnetic Fields Induce Spermatogenic Germ Cell Apoptosis: Possible Mechanism

    Directory of Open Access Journals (Sweden)

    Sang-Kon Lee

    2014-01-01

    Full Text Available The energy generated by an extremely low frequency electromagnetic field (ELF-EMF is too weak to directly induce genotoxicity. However, it is reported that an extremely low frequency magnetic field (ELF-MF is related to DNA strand breakage and apoptosis. The testes that conduct spermatogenesis through a dynamic cellular process involving meiosis and mitosis seem vulnerable to external stress such as heat, MF exposure, and chemical or physical agents. Nevertheless the results regarding adverse effects of ELF-EMF on human or animal reproductive functions are inconclusive. According to the guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP; 2010 for limiting exposure to time-varying MF (1 Hz to 100 kHz, overall conclusion of epidemiologic studies has not consistently shown an association between human adverse reproductive outcomes and maternal or paternal exposure to low frequency fields. In animal studies there is no compelling evidence of causal relationship between prenatal development and ELF-MF exposure. However there is increasing evidence that EL-EMF exposure is involved with germ cell apoptosis in testes. Biophysical mechanism by which ELF-MF induces germ cell apoptosis has not been established. This review proposes the possible mechanism of germ cell apoptosis in testes induced by ELF-MF.

  5. Unconventional Specimen Preparation Techniques Using High Resolution Low Voltage Field Emission Scanning Electron Microscopy to Study Cell Motility, Host Cell Invasion, and Internal Cell Structures in Toxoplasma gondii

    Science.gov (United States)

    Schatten, Heide; Ris, Hans

    2002-04-01

    Apicomplexan parasites employ complex and unconventional mechanisms for cell locomotion, host cell invasion, and cell division that are only poorly understood. While immunofluorescence and conventional transmission electron microscopy have been used to answer questions about the localization of some cytoskeletal proteins and cell organelles, many questions remain unanswered, partly because new methods are needed to study the complex interactions of cytoskeletal proteins and organelles that play a role in cell locomotion, host cell invasion, and cell division. The choice of fixation and preparation methods has proven critical for the analysis of cytoskeletal proteins because of the rapid turnover of actin filaments and the dense spatial organization of the cytoskeleton and its association with the complex membrane system. Here we introduce new methods to study structural aspects of cytoskeletal motility, host cell invasion, and cell division of Toxoplasma gondii, a most suitable laboratory model that is representative of apicomplexan parasites. The novel approach in our experiments is the use of high resolution low voltage field emission scanning electron microscopy (LVFESEM) combined with two new specimen preparation techniques. The first method uses LVFESEM after membrane extraction and stabilization of the cytoskeleton. This method allows viewing of actin filaments which had not been possible with any other method available so far. The second approach of imaging the parasite's ultrastructure and interactions with host cells uses semithick sections (200 nm) that are resin de-embedded (Ris and Malecki, 1993) and imaged with LVFESEM. This method allows analysis of structural detail in the parasite before and after host cell invasion and interactions with the membrane of the parasitophorous vacuole as well as parasite cell division.

  6. High Brightness Neutron Source for Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

    2008-12-08

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  7. Highly conductive composites for fuel cell flow field plates and bipolar plates

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Bor Z; Zhamu, Aruna; Song, Lulu

    2014-10-21

    This invention provides a fuel cell flow field plate or bipolar plate having flow channels on faces of the plate, comprising an electrically conductive polymer composite. The composite is composed of (A) at least 50% by weight of a conductive filler, comprising at least 5% by weight reinforcement fibers, expanded graphite platelets, graphitic nano-fibers, and/or carbon nano-tubes; (B) polymer matrix material at 1 to 49.9% by weight; and (C) a polymer binder at 0.1 to 10% by weight; wherein the sum of the conductive filler weight %, polymer matrix weight % and polymer binder weight % equals 100% and the bulk electrical conductivity of the flow field or bipolar plate is at least 100 S/cm. The invention also provides a continuous process for cost-effective mass production of the conductive composite-based flow field or bipolar plate.

  8. Threshold and saturation properties of the field-induced twist cell with two parameters weak anchoring boundaries

    Institute of Scientific and Technical Information of China (English)

    Guan Rong-Hua; Sun Yu-Bao

    2006-01-01

    On the basis of two-parameter formula of weak surface coupling anchoring energy of nematic liquid crystals proposed by Zhao et al recently, the general torque equilibrium equation and boundary conditions of the director have been obtained and the threshold field as well as the saturation field of the field-induced twist cell have been analysed for three kinds of configurations, i.e. homogeneous, splay and Pi cells formed by different rubbing conditions and pretilt angles. The results indicated that the polar anchoring has no effect on the threshold field. It is determined only by the twist anchoring and pretilt angle. But, the polar anchoring and twist anchoring are coupling with each other and have a great influence on the saturation field. The formulae for calculating the threshold field and saturation field are given.These results will be very useful in understanding surface physics and the design of liquid crystal cells.

  9. Ultra-bright alkylated graphene quantum dots

    Science.gov (United States)

    Feng, Lan; Tang, Xing-Yan; Zhong, Yun-Xin; Liu, Yue-Wen; Song, Xue-Huan; Deng, Shun-Liu; Xie, Su-Yuan; Yan, Jia-Wei; Zheng, Lan-Sun

    2014-10-01

    Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The photocatalytic rate is ca. 5.9 times higher than that of pure P25, indicating that AGQDs could harness the visible spectrum of sunlight for energy conversion or environmental therapy.Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The

  10. Mesenchymal stem cells that located in the electromagnetic fields improves rat model of Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Majid Jadidi

    2016-07-01

    Full Text Available Objective(s: The main characteristic of mesenchymal stem cells (MSCs is their ability to produce other cell types. Electromagnetic field (EMF stimulates differentiation of MSCs into other cells. In this study, we investigated whether EMF can effect on the differentiation of MSCs into dopaminergic (DA neurons. Materials and Methods: An EMF with a frequency of 50 Hz and two intensities of 40 and 400 µT 1hr/day was generated around the cells for a week. Afterwards, these cells were injected into the left ventricle of Parkinsonian rats. The rats survived for 2 weeks, and then sampling was performed. Results: The injected cells differentiated into DA neurons and sporadically settled in the substantia nigra pars compacta (SNpc. Transplanted rats exhibited significant partial correction apomorphine-induced rotational behavior compared to Parkinsonian rats (5.0±0.1 vs 7.57±0.08. Results demonstrated that endogenous serum and brain derived neurotrophic factor (BDNF were altered in all experimental groups. The greatest increase was in group of 400 µT EMF in comparison with Parkinsonian rats (398±15 vs. 312±11.79 pg ⁄ mg. Current study have shown that 6-Hydroxydopamine can cause severe loss of dopaminergic neurons (68±6.58, but injected MSCs that exposed to 40 and 400 µT EMF increased dopaminergic neurons in SNpc ( 108±2.33  & 126±3.89 (P

  11. Plasmon-enhanced photocathode for high brightness and high repetition rate x-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Polyakov, Aleksandr; Senft, Christoph; Thompson, K. F.; Feng, J.; Cabrini, S.; Schuck, P. J.; Padmore, Howard; Peppernick, Samuel J.; Hess, Wayne P.

    2013-02-11

    High brightness electron sources are at the heart of anew generation of x-ray sources based on the Free ElectronLaser (FEL) as well as in Energy Recovery Linac (ERL) and Inverse Compton Scattering (ICS) sources.The source of electrons consists of a photoinjector, comprised of a laser-driven photocathode in a high gradient electric field produced by an rf cavity. The function of the rf cavity is to provide a field sufficient for acceleration of electrons to relativistic velocity over a small distance, thus minimizing effects of the space-charge. Even so, the dense electron beam required for high brightness suffers from a space charge field that chirps and reshapes the electron pulse increasing beam emittance and thus reducing the overall brightness. This emittance growth can be avoided if the initial distribution of electrons is pancake shaped, with a semicircular transverse intensity profile. In this case, the electron distribution develops under its space charge field from a pancake into a uniformly filled ellipsoidal beam. This condition, referred to as the blowout regime, requires ultrashort pulses less than 100 fs long and has been successfully demonstrated recently in a high gradient photoinjector.

  12. Bright Transients from Black Hole - Neutron Star Mergers

    CERN Document Server

    D'Orazio, Daniel J; Murray, Norman W; Price, Larry

    2016-01-01

    Direct detection of black hole-neutron star (BHNS) pairs is anticipated with the advent of aLIGO. Electromagnetic counterparts may be crucial for a confident gravitational-wave detection as well as for extraction of astronomical information. Yet BHNS star pairs are notoriously dark and so inaccessible to telescopes. Contrary to this expectation, a bright electromagnetic transient can occur in the final moments before merger as long as the neutron star is highly magnetized. The orbital motion of the neutron star magnet creates a Faraday flux and corresponding power available for luminosity. A spectrum of curvature radiation ramps up until the rapid injection of energy ignites a fireball, which would appear as an energetic blackbody peaking in the X-ray to gamma-rays for neutron star field strengths ranging from $10^{12}$G to $10^{16}$G respectively and a $10M_{\\odot}$ black hole. The fireball event may last from a few milliseconds to a few seconds depending on the NS magnetic field strength, and may be observa...

  13. QUIET-SUN NETWORK BRIGHT POINT PHENOMENA WITH SIGMOIDAL SIGNATURES

    Energy Technology Data Exchange (ETDEWEB)

    Chesny, D. L.; Oluseyi, H. M. [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Orange, N. B. [OrangeWave Innovative Science, LLC, Moncks Corner, SC 29461 (United States); Champey, P. R. [Department of Optical Science and Engineering, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  14. Effects of ELF magnetic fields on protein expression profile of human breast cancer cell MCF7

    Institute of Scientific and Technical Information of China (English)

    LI; Han; ZENG; Qunli; WENG; Yu; LU; Deqiang; JIANG; Huai; XU

    2005-01-01

    Extremely Low Frequency Magnetic Fields (ELF MF) has been considered as a "possible human carcinogen" by International Agency for Research on Cancer (IARC) while credible mechanisms of its carcinogenicity remain unknown. In this study, a proteomics approach was employed to investigate the changes of protein expression profile induced by ELF MF in human breast cancer cell line MCF7, in order to determine ELF MF-responsive proteins. MCF7 cells were exposed to 50 Hz, 0.4 mT ELF MF for 24 h and the changes of protein profile were examined using two dimensional electrophoresis. Up to 6 spots have been statistically significantly altered (their expression levels were changed at least 5 fold up or down) compared with sham-exposed group. 19 ones were only detected in exposure group while 19 ones were missing. Three proteins were identified by LC-IT Tandem MS as RNA binding protein regulatory subunit、Proteasome subunit beta type 7 precursor and Translationally Controlled Tumor Protein. Our finding showed that 50 Hz, 0.4 mT ELF MF alternates the protein profile of MCF7 cell and may affect many physiological functions of normal cell and 2-DE coupled with MS is a promising approach to elucidating cellular effects of electromagnetic fields.

  15. Cost-effective and Rapid Blood Analysis on a Cell-phone

    OpenAIRE

    Zhu, Hongying; Sencan, Ikbal; Wong, Justin; Dimitrov, Stoyan; Tseng, Derek; Nagashima, Keita; Ozcan, Aydogan

    2013-01-01

    We demonstrate a compact and cost-effective imaging cytometry platform installed on a cell-phone for the measurement of the density of red and white blood cells as well as hemoglobin concentration in human blood samples. Fluorescent and bright-field images of blood samples are captured using separate optical attachments to the cell-phone and are rapidly processed through a custom-developed smart application running on the phone for counting of blood cells and determining hemoglobin density. W...

  16. The effects of applied electric fields on Micrasterias. I. Morphogenesis and the pattern of cell wall deposition.

    Science.gov (United States)

    Brower, D L; McIntosh, J R

    1980-04-01

    Applied electric fields of approximately 14 V/cm have profound effects on the morphogenesis of the unicellular green alga, Micrasterias denticulata. This field corresponds to a potential drop of 15-40 mV across lobes oriented perpendicular to the applied field. These lobes show a galvanotropism toward the cathode. Lobes growing parallel to the field are stunted to varying degrees, depending on their orientation. As shown by other investigators, most cell wall material is normally deposited at the tips of growing lobes. If, however, cell expansion is osmotically inhibited in electric fields, wall material also accumulates along the cathode-facing (CF) sides of lobes oriented perpendicular to the field. Similarly, in cells growing under the influence of an applied field, radioactively labelled glucose and the methyl groups from methionine are incorporated along the CF sides of lobes as well as the lobe tips. This is also true when the label is added immediately after cells are removed from the fields, indicating that the wall-depositing machinery itself has been temporarily altered by the field. These results demonstrate that applied electric fields can be a valuable tool in elucidating the mechanisms of growth localization in Micrasterias cells. PMID:7400236

  17. The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field.

    Science.gov (United States)

    Nguyen, The Hong Phong; Pham, Vy T H; Nguyen, Song Ha; Baulin, Vladimir; Croft, Rodney J; Phillips, Brian; Crawford, Russell J; Ivanova, Elena P

    2016-01-01

    The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8T. PMID:27391488

  18. The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field

    Science.gov (United States)

    Pham, Vy T. H.; Nguyen, Song Ha; Baulin, Vladimir; Croft, Rodney J.; Phillips, Brian; Crawford, Russell J.

    2016-01-01

    The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8T. PMID:27391488

  19. The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field.

    Science.gov (United States)

    Nguyen, The Hong Phong; Pham, Vy T H; Nguyen, Song Ha; Baulin, Vladimir; Croft, Rodney J; Phillips, Brian; Crawford, Russell J; Ivanova, Elena P

    2016-01-01

    The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8T.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Karoline M. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Guhathakurta, Puragra [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Beaton, Rachael L.; Majewski, Steven R.; Ostheimer, James C.; Patterson, Richard J. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Bullock, James; Tollerud, Erik J. [Center for Cosmology, Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697 (United States); Geha, Marla C. [Astronomy Department, Yale University, New Haven, CT 06520 (United States); Kalirai, Jason S. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Kirby, Evan N. [California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Tanaka, Mikito; Chiba, Masashi, E-mail: kgilbert@astro.washington.edu [Astronomical Institute, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)

    2012-11-20

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

  1. Dark and bright vortex solitons in electromagnetically induced transparent media

    International Nuclear Information System (INIS)

    We show that dark and bright vortex solitons can exist in three-state electromagnetically induced transparent media under some appropriate conditions. We also analyse the stability of the dark and bright vortex solitons. This work may provide other research opportunities in nonlinear optical experiments and may result in a substantial impact on technology

  2. Low dimensional neutron moderators for enhanced source brightness

    DEFF Research Database (Denmark)

    Mezei, Ferenc; Zanini, Luca; Takibayev, Alan;

    2014-01-01

    for cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared...

  3. Surface photometry of bulge dominated low surface brightness galaxies

    NARCIS (Netherlands)

    Beijersbergen, M; de Blok, WJG; van der Hulst, JM

    1999-01-01

    We present results of broad band BVRI observations of a sample of galaxies with a low surface brightness (LSB) disk and a bulge. These galaxies are well described as exponential disks and exponential bulges with no preferred value for either scale length or central surface brightness. The median B b

  4. Analysis of Bright Harvest Remote Analysis for Residential Solar Installations

    Energy Technology Data Exchange (ETDEWEB)

    Nangle, John [National Renewable Energy Lab. (NREL), Golden, CO (United States); Simon, Joseph [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-06-17

    Bright Harvest provides remote shading analysis and design products for residential PV system installers. The National Renewable Energy Laboratory (NREL) through the NREL Commercialization Assistance Program, completed comparative assessments between on-site measurements and remotely calculated values to validate the accuracy of Bright Harvest’s remote shading and power generation.

  5. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.; Butterfield, Karla [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.

    2016-03-01

    Kaplan Thompson Architects (KTA) has specialized in sustainable, energy-efficient buildings, and they have designed several custom, zero-energy homes in New England. These zero-energy projects have generally been high-end, custom homes with budgets that could accommodate advanced energy systems. In an attempt to make zero energy homes more affordable and accessible to a larger demographic, KTA explored modular construction as way to provide high-quality homes at lower costs. In the mid-2013, KTA formalized this concept when they launched BrightBuilt Home (BBH). The BBH mission is to offer a line of architect-designed, high-performance homes that are priced to offer substantial savings off the lifetime cost of a typical home and can be delivered in less time. For the past two years, CARB has worked with BBH and Keiser Homes (the primary modular manufacturer for BBH) to discuss challenges related to wall systems, HVAC, and quality control. In Spring of 2014, CARB and BBH began looking in detail on a home to be built in Lincolnville, ME by Black Bros. Builders. This report details the solution package specified for this modular plan and the challenges that arose during the project.

  6. Lyman Alpha Mapping Project (LAMP) Brightness Maps

    Science.gov (United States)

    Retherford, Kurt D.; Gladstone, G.; Stern, S.; Egan, A. F.; Miles, P. F.; Parker, J. W.; Greathouse, T. K.; Davis, M. W.; Slater, D. C.; Kaufmann, D. E.; Versteeg, M. H.; Feldman, P. D.; Hurley, D. M.; Pryor, W. R.; Hendrix, A. R.

    2010-10-01

    The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is designed to map the lunar albedo at far-UV wavelengths. LAMP primarily measures interplanetary Hydrogen Lyman-alpha sky-glow and far-UV starlight reflected from the night-side lunar surface, including permanently shadowed regions (PSRs) near the poles. Dayside observations are also obtained. Brightness maps sorted by wavelength (including the Lyman-alpha wavelength of 121.6 nm) are reported for the polar regions, with a few regions of interest reported in more detail. LAMP's spectral range of 58 nm to 196 nm includes a water ice spectral feature near 160 nm, which provides a diagnostic tool for detecting water on the lunar surface that is complementary to recent discoveries using infrared and radio frequency techniques. Progress towards producing far-UV albedo maps and searching for water ice signatures will be reported. We'll discuss how LAMP data may address questions regarding how water is formed on the moon, transported through the lunar atmosphere, and deposited in the PSRs.

  7. Dark Skies, Bright Kids Year 6

    Science.gov (United States)

    Liss, Sandra; Troup, Nicholas William; Johnson, Kelsey E.; Barcos-Munoz, Loreto D.; Beaton, Rachael; Bittle, Lauren; Borish, Henry J.; Burkhardt, Andrew; Corby, Joanna; Dean, Janice; Hancock, Danielle; King, Jennie; Prager, Brian; Romero, Charles; Sokal, Kimberly R.; Stierwalt, Sabrina; Wenger, Trey; Zucker, Catherine

    2015-01-01

    Now entering our sixth year of operation, Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in central Virginia through fun, hands-on activities that introduce basic Astronomy concepts beyond Virginia's Standards of Learning. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.DSBK has amassed over 15,000 contact hours since 2009 and we continue to broaden our impact. One important step we have taken in the past year is to establish a graduate student led assessment program to identify and implement directed learning goals for DSBK outreach. The collection of student workbooks, observations, and volunteer surveys indicates broad scale success for the program both in terms of student learning and their perception of science. The data also reveal opportunities to improve our organizational and educational practices to maximize student achievement and overall volunteer satisfaction for DSBK's future clubs and outreach endeavors.

  8. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new mechanical electrodeposition technology was proposed, and nanocrystalline nickel deposit with bright and smooth surface was prepared in the bath without any additive agents. Unlike traditional methods, the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing. Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits, pinholes and nodules. Furthermore, comparing with the deposit prepared by traditional methods, the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm. Every diffraction peak’s intensity of the deposit was reduced, the preferential orientation degree of (200) decreased and those of (111) and (220) increased. The microhardness notably increased. The magnetic properties were also changed with decreased saturation magnetization and increased coercive force. It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.

  9. Chromatic variations suppress suprathreshold brightness variations.

    Science.gov (United States)

    Kingdom, Frederick A A; Bell, Jason; Gheorghiu, Elena; Malkoc, Gokhan

    2010-01-01

    Most objects in natural scenes are suprathreshold in both color (chromatic) and luminance contrast. How salient is each dimension? We have developed a novel method employing a stimulus similar to that used by B. C. Regan and J. D. Mollon (1997) who studied the relative saliencies of the two chromatic cardinal directions. Our stimuli consist of left- and right-oblique modulations of color and/or luminance defined within a lattice of circles. In the "separated" condition, the two modulations were presented separately as forced-choice pairs, and the task was to indicate which was more salient. In the "combined" condition, the two orthogonal-in-orientation modulations were added, and the task was to indicate the more salient orientation. The ratio of color to luminance contrast at the PSE was calculated for both conditions. Across color directions, 48% more luminance contrast relative to color contrast was required to achieve a PSE in the "combined" compared to the "separated" condition. A second experiment showed that the PSE difference was due to the luminance being masked by the color, rather than due to superior color grouping. We conclude that suprathreshold brightness variations are masked by suprathreshold color variations. PMID:20884478

  10. Intercomparisons of Nine Sky Brightness Detectors

    Directory of Open Access Journals (Sweden)

    Henk Spoelstra

    2011-10-01

    Full Text Available Nine Sky Quality Meters (SQMs have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across the Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from −16% to +20%. Intercalibration reduces this to 0.5%, and −7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m2 on 12 April, and the largest value was 5.94 ± 0.03 mcd/m2 on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  11. PNAS Plus: Origin of first cells at terrestrial, anoxic geothermal fields

    Science.gov (United States)

    Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.

    2012-04-01

    All cells contain much more potassium, phosphate, and transition metals than modern (or reconstructed primeval) oceans, lakes, or rivers. Cells maintain ion gradients by using sophisticated, energy-dependent membrane enzymes (membrane pumps) that are embedded in elaborate ion-tight membranes. The first cells could possess neither ion-tight membranes nor membrane pumps, so the concentrations of small inorganic molecules and ions within protocells and in their environment would equilibrate. Hence, the ion composition of modern cells might reflect the inorganic ion composition of the habitats of protocells. We attempted to reconstruct the "hatcheries" of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells. These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K+, Zn2+, Mn2+, and phosphate. Thus, protocells must have evolved in habitats with a high K+/Na+ ratio and relatively high concentrations of Zn, Mn, and phosphorous compounds. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapor-dominated zones of inland geothermal systems. Under the anoxic, CO2-dominated primordial atmosphere, the chemistry of basins at geothermal fields would resemble the internal milieu of modern cells. The precellular stages of evolution might have transpired in shallow ponds of condensed and cooled geothermal vapor that were lined with porous silicate minerals mixed with metal sulfides and enriched in K+, Zn2+, and phosphorous compounds.

  12. Effects of 60 Hz electromagnetic field exposure on testicular germ cell apoptosis in mice

    Institute of Scientific and Technical Information of China (English)

    JinSangLee; SangSeokAhn; KyeongCheonJung; Yoon-WonKim; SangKonLee

    2004-01-01

    Aim:To evaluate the effects of 60 Hz extremely low frequency (ELF) elelctromagnetic field (EMF) exposure on germ cell apoptosis in the testis of mice.Methods:Adult male BALB/c mice (7 weeks of age) were exposed to a 60 Hz EMF of 0.1 mT or 0.5 mT for 24 h/day.A sham-exposed group served as the control.After 8 weeks of exposure,the mice were sacrificed.Germ cell apoptosis in the testis was assessed by histopathological examination,the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) and flow cytometric examination of isolated spermatogenic cells stained with 7 aminoactinomycin D (7-AAD).Results:EMF exposure did not significantly affect the body and testis weights,but significantly increased the incidence of germ cell death.The distinguishing morphological feature of EMF exposure was a decrement in the number of well organized seminiferous tubules.Quantitative analysis of TUNEL-positive germ cells showed a significantly higher apoptotic rate in the 0.5 mT exposed mice than that in the sham controls (P<0.05),while the difference between the two exposed groups was insignificant.The TUNEL-positive cells were mainly spermatogonia.In flow cytometryanalysis,the percentage of live cells [forward scatter count (FSC)hgh7-AAD-] was lower in the exposed groups than that in the controls (Figure 5A),but the decrease in viability was not statistically significant.Conclusion:Continuousexposure to ELF EMF may induce testicular germ cell apoptosis in mice.(Asian J Androl 2004 Mar;6:29-34)

  13. Endothelial Cell Morphology and Migration are Altered by Changes in Gravitational Fields

    Science.gov (United States)

    Melhado, Caroline; Sanford, Gary; Harris-Hooker, Sandra

    1997-01-01

    vascular cells. However, few studies have been directed at assessing the effect of altered gravitational field on vascular cell fiction and metabolism, Using image analysis we examined how bovine aortic endothelial cells altered their morphological characteristics and their response to a denudation injury when cells were subjected to simulated microgravity and hypergravity.

  14. Magnetophotocurrent in Organic Bulk Heterojunction Photovoltaic Cells at Low Temperatures and High Magnetic Fields

    Science.gov (United States)

    Khachatryan, B.; Devir-Wolfman, A. H.; Tzabari, L.; Tessler, N.; Vardeny, Z. V.; Ehrenfreund, E.

    2016-04-01

    We study high-field (up to B ˜8.5 T ) magnetophotocurrent (MPC) related to photogenerated polaron pairs (PPs) in the temperature range T =10 - 320 K in organic bulk heterojunction photovoltaic cells. We find that in the high-field regime (B >1 T ), MPC (B ) response increases with B for temperature T >200 K but decreases with B at T <200 K . MPC (B ) response does not saturate even at the highest field studied, at all T . We attribute the observed high-field MPC (B ) response to two competing mechanisms within the PP spin states: (a) a spin-mixing mechanism caused by the difference in the donor-acceptor (or positive-negative polarons) g factors (the so-called "Δ g mechanism"), and (b) the spin polarization induced by thermal population of the PP Zeeman split levels. The nonsaturating MPC (B ) response at high fields and high temperatures indicates that there exist charge-transfer excitons (CTEs) with decay time in the subnanosecond time domain. With decreasing temperature, the CTE decay time sharply increases, thereby promoting an increase of the thermal spin-polarization contribution to the MPC (B ) response.

  15. Ferroelectric field effect of the bulk heterojunction in polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meng; Ma, Heng, E-mail: hengma@henannu.edu.cn; Liu, Hairui; Jiang, Yurong [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007 (China); Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007 (China); Niu, Heying; Amat, Adil [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007 (China)

    2014-06-23

    A ferroelectric field effect in the bulk heterojunction was found when an external electric field (EEF) was applied on the active layer of polymer solar cells (PSCs) during the annealing process of the active layer spin-coated with poly(3-hexylthiophene):[6,6]-phenyl-C{sub 61} butyric acid methyl ester. For one direction field, the short circuit current density of PSCs was improved from 7.2 to 8.0 mA/cm{sup 2}, the power conversion efficiency increased from 2.4% to 2.8%, and the incident photon-to-current conversion efficiency increased from 42% to 49% corresponding to the different EEF magnitude. For an opposite direction field, the applied EEF brought a minus effect on the performance mentioned above. EEF treatment can orientate molecular ordering of the polymer, and change the morphology of the active layer. The authors suggest a explanation that the ferroelectric field has been built in the active layer, and therefore it plays a key role in PSCs system. A needle-like surface morphology of the active film was also discussed.

  16. Bright patches on chernozems - from space to surface and soil properties

    Science.gov (United States)

    Smetanova, Anna; Burian, Libor; Holec, Juraj; Minár, Jozef

    2016-04-01

    The bright patches on chernozems can be easily visually distinguished in the aerial images, due to their bright colour contrasting with the dark colour of the surrounding chernozems. They present a typical feature of the loess hilly lands in the Danube Lowland. They reffer predominantely to the areas where (i) the soil substrate - loess is tilled, (ii) the transitional AC horizon of chernozems is tilled, (iii) or one of them, or both are mixed into the plough layer during tillage. They are usually categorized as eroded chernozems or regosols. To the lower extent, the accumulation patches might occur, if the loess material redeposited from upper part of the slope in the colluvium is tilled. This study focuses on uncovering the soil properties of bright patches, identified on different scales - spatial and temporal, combining three methods - the remote sensing, morphometric analysis and soil mapping. In the area of 31 km² (located in the Trnavska pahorkatina Hilly Land, south of Trnava), the bright patches were identified using visual analysis of georeferenced aerial images from 1949 and 2004, representing two types of landscape structure characteristic for the 20th Century. In 1949 small, in one direction elongated fields, with mean size 0.008 km2 prevailed, while in 2004 the mean size of a field was 0.28 km2. The morphometric analysis was performed based on DEM derived from topographical maps (scale 1:10 000). Soil sampling in the first phase of the project was performed in a subset of the patches in small agriculture catchment (0.28 km2), situated in one single field (in 2004). The percussion drilling or hand augering (with undisturbed structure) were used in order to describe the depth of the soil horizons and the soil properties. Together 365 bright patches covering 3.2% of the study area (31 km²) were identified in 1949; while it was twice more in 2004 (776 patches), when they covered approximately 12% of the same area. The bright patches were predominantly

  17. BRIGHT BROADBAND AFTERGLOWS OF GRAVITATIONAL WAVE BURSTS FROM MERGERS OF BINARY NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Gao He; Ding Xuan; Wu Xuefeng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang Bing [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States); Dai Zigao, E-mail: xfwu@pmo.ac.cn, E-mail: zhang@physics.unlv.edu, E-mail: dzg@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-07-10

    If double neutron star mergers leave behind a massive magnetar rather than a black hole, then a bright early afterglow can follow the gravitational wave burst (GWB) even if there is no short gamma-ray burst (SGRB)-GWB association or if there is an association but the SGRB does not beam toward Earth. Besides directly dissipating the proto-magnetar wind, as suggested by Zhang, here we suggest that the magnetar wind could push the ejecta launched during the merger process and, under certain conditions, would reach a relativistic speed. Such a magnetar-powered ejecta, when interacting with the ambient medium, would develop a bright broadband afterglow due to synchrotron radiation. We study this physical scenario in detail and present the predicted X-ray, optical, and radio light curves for a range of magnetar and ejecta parameters. We show that the X-ray and optical light curves usually peak around the magnetar spin-down timescale ({approx}10{sup 3}-10{sup 5} s), reaching brightnesses readily detectable by wide-field X-ray and optical telescopes, and remain detectable for an extended period. The radio afterglow peaks later, but is much brighter than the case without a magnetar energy injection. Therefore, such bright broadband afterglows, if detected and combined with GWBs in the future, would be a probe of massive millisecond magnetars and stiff equations of state for nuclear matter.

  18. Using a New Sky Brightness Monitor to Observe the Annular Solar Eclipse on 15 January 2010

    CERN Document Server

    Liu, Y; Zhang, X -F; Liu, N -P

    2012-01-01

    For the future development of Chinese Giant Solar Telescope (CGST) in Western China, a new sky brightness monitor (SBM) has been produced for the site survey for CGST. To critically examine the performance and sensitivity of SBM, we used it in the observation of the annular solar eclipse in Dali City, Yunnan, on 15 January 2010. The observation met good weather condition with almost clear sky during the eclipse. The SBM measurement translates into the solar illuminance changes at a level of 2.4 \\times 10-4I s-1 during the eclipse. The time of the minimal sky brightness in the field of view (FOV) is found consistent with the time of maximum eclipse. Two local sky regions in the FOV are chosen to make time series of calibrated skylight profiles. The evolution of the sky brightness thus calibrated also shows good consistency with the eclipse, particularly between the second and the third contacts. The minimal sky brightness in each local sky region took place within half a minute from the corresponding predicted...

  19. MODIS BRIGHTNESS TEMPERATURE DATA ASSIMILATION UNDER CLOUDY CONDITIONS: METHODS AND IDEAL TESTS

    Institute of Scientific and Technical Information of China (English)

    DING Wei-yu; WAN Qi-lin; ZHANG Chen-zhong; CHEN Zi-tong; HUANG Yan-yan

    2010-01-01

    Clouds have important effects on the infrared radiances transmission in that the inclusion of cloud effects in data assimilation can not only improve the quality of the assimilated atmospheric parameters greatly, but also minimize the initial error of cloud parameters by adjusting part of the infrared radiances data. On the basis of the Grapes-3D-var (Global and Regional Assimilation and Prediction Enhanced System), cloud liquid water, cloud ice water and cloud cover are added as the governing variables in the assimilation. Under the conditions of clear sky, partly cloudy cover and totally cloudy cover, the brightness temperature of 16 MODIS channels are assimilated respectively in ideal tests. Results show that when the simulated background brightness temperatures are lower than the observation, the analyzed field will increase the simulated brightness temperature by increasing its temperature and reducing its moisture, cloud liquid water, cloud ice water, and cloud cover. The simulated brightness temperature can be reduced if adjustment is made in the contrary direction. The adjustment of the temperature and specific humidity under the clear sky conditions conforms well to the design of MODIS channels, but it is weakened for levels under cloud layers. The ideal tests demonstrate that by simultaneously adding both cloud parameters and atmospheric parameters as governing variables during the assimilation of infrared radiances, both the cloud parameters and atmospheric parameters can be adjusted using the observed infrared radiances and conventional meteorological elements to make full use of the infrared observations.

  20. Interpreting Central Surface Brightness and Color Profiles in Elliptical Galaxies

    Science.gov (United States)

    Silva, David R.; Wise, Michael W.

    1996-01-01

    Hubble Space Telescope imagery has revealed dust features in the central regions of many (50%--80%) nearby bright elliptical galaxies. If these features are an indication of an underlying smooth diffuse dust distribution, then the interpretation of central surface brightness and color profiles in elliptical galaxies becomes significantly more difficult. In this Letter, diagnostics for constraining the presence of such an underlying central dust distribution are presented. We show that easily detectable central color gradients and flattened central surface brightness profiles can be induced by even small amounts of smoothly distributed dust (~100 M⊙). Conversely, combinations of flat surface brightness profiles and flat color gradients or steep surface brightness profiles and steep color gradients are unlikely to be caused by dust. Taken as a whole, these results provide a simple observational tautology for constraining the existence of smooth diffuse dust distributions in the central regions of elliptical galaxies.

  1. Rapid Brightness Variations as a Tool to Enhance Satellite Detectability

    Science.gov (United States)

    Laas-Bourez, Myrtille; Klotz, Alain; Ducrotte, Etienne; Boer, Michel; Blanchet, Gwendoline

    2009-03-01

    To preserve the space environment for future generations and ensure the safety of space missions, we have to improve our knowledge of the debris at all altitudes. Since 2004, we have started to observe and study satellites and debris on the geostationary orbit. We use a network of robotic telescopes called TAROT (Télescopes Action Rapide pour les Objets Transitoires - Rapid Action Telescope for Transient Objects) which are located in France and Chile. This system processes the data in real time. Its wide field of view is useful for detection, systematic survey and to follow both catalogued and uncatalogued objects. The TAROTs are 25 cm telescopes with a wide field of view of 1.86deg x 1.86deg. It can detect objects up to 17th magnitude with an integration time of 30 seconds, corresponding to an object of 50cm in the geostationary belt with a 0.2 albedo. Tiny debris are also dangerous for space mission and satellites. To detect them, we need either to increase the TAROT sensitivity or to observe them in optimal light conditions.Last year we detected very important magnitude variations from several geostationary satellites during observations close to equinoxes. The brightness of a geostationary satellite evolves during the night and during the year, depending on the angle between the observer, the satellite and the sun. Geostationary satellites will be brighter near March 1st and of October 10th, at their exit of the shade. In this period the sun crosses the equatorial plan of the Earth, the enlightened surface will reach a maximum during a limited periods of time (about 30 minutes), provoking a short, bright flash. This phenomenon is used in two ways: first, it allows to detect smaller objects, which are usually below the detection limit, enhancing the sensitivity of the survey. Secondly, for longer objects the light curve during and outside the °ash contains information on the object intrinsic geometry and reflectivity. In this paper we discuss how the various

  2. Demonstration of a bright and compact source of tripartite nonclassical light

    OpenAIRE

    Allevi, Alessia; Bondani, Maria; Paris, Matteo G. A.; Andreoni, Alessandra

    2008-01-01

    We experimentally demonstrate the nonclassical photon number correlations expected in tripartite continuous variable states obtained by parametric processes. Our scheme involves a single nonlinear crystal, where two interlinked parametric interactions take place simultaneously, and represents a bright and compact source of a sub-shot-noise tripartite light field. We analyze the effects of the pump intensities on the numbers of detected photons and on the amount of noise reduction in some deta...

  3. Release and fate of fluorocarbons in a shredder residue landfill cell: 2. Field investigations.

    Science.gov (United States)

    Scheutz, Charlotte; Fredenslund, Anders M; Nedenskov, Jonas; Kjeldsen, Peter

    2010-11-01

    The shredder residues from automobiles, home appliances and other metal containing products are often disposed in landfills, as recycling technologies for these materials are not common in many countries. Shredder waste contains rigid and soft foams from cushions and insulation panels blown with fluorocarbons. The objective of this study was to determine the gas composition, attenuation, and emission of fluorocarbons in a monofill shredder residue landfill cell by field investigation. Landfill gas generated within the shredder waste primarily consisted of CH(4) (27%) and N(2) (71%), without CO(2), indicating that the gas composition was governed by chemical reactions in combination with anaerobic microbial reactions. The gas generated also contained different fluorocarbons (up to 27 μg L(-1)). The presence of HCFC-21 and HCFC-31 indicated that anaerobic degradation of CFC-11 occurred in the landfill cell, as neither of these compounds has been produced for industrial applications. This study demonstrates that a landfill cell containing shredder waste has a potential for attenuating CFC-11 released from polyurethane (PUR) insulation foam in the cell via aerobic and anaerobic biodegradation processes. In deeper, anaerobic zones of the cell, reductive dechlorination of CFCs to HCFCs was evident, while in the shallow, oxic zones, there was a high potential for biooxidation of both methane and lesser chlorinated fluorocarbons. These findings correlated well with both laboratory results (presented in a companion paper) and surface emission measurements that, with the exception from a few hot spots, indicated that surface emissions were negative or below detection. PMID:20444588

  4. Locally resolved measurements in a segmented HTPEM fuel cell with straight flow-fields

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, C. [Zentrum fuer BrennstoffzellenTechnik (ZBT), GmbH (Centre for Fuel Cell Technology), Carl-Benz-Str. 201, D-47057 Duisburg (Germany); University of Duisburg-Essen, Institut fuer Energie- und Umweltverfahrenstechnik, Lotharstr. 1, D-47048 Duisburg (Germany); Siegel Schleimer Ingenieurs-Conseils s.a r.l. - Engineering and research, 2A, rue d' Ehlerange, L-3918 Mondercange (Luxembourg); Bandlamudi, G.; Heinzel, A. [Zentrum fuer BrennstoffzellenTechnik (ZBT), GmbH (Centre for Fuel Cell Technology), Carl-Benz-Str. 201, D-47057 Duisburg (Germany); University of Duisburg-Essen, Institut fuer Energie- und Umweltverfahrenstechnik, Lotharstr. 1, D-47048 Duisburg (Germany); Filusch, F. [Zentrum fuer BrennstoffzellenTechnik (ZBT), GmbH (Centre for Fuel Cell Technology), Carl-Benz-Str. 201, D-47057 Duisburg (Germany)

    2011-08-15

    Significant advances have been reported in building and testing of high-temperature polymer electrolyte membrane (HTPEM) fuel cells and stacks during recent years. Quantity distribution measurement techniques (e.g. current density, temperature and electrochemical impedance spectroscopy (EIS)) using segmented cells are commonly used to characterise low-temperature PEM (LTPEM) fuel cells. Performing these measurements at higher temperatures is more difficult and a relatively new process. For this study, a fully operational segmented HTPEM fuel cell using a straight flow-field configuration was designed, constructed and tested. The cathode side bipolar half-plate consisted of 36 exchangeable segments, whereas, the anode side bipolar half-plate was not segmented. The cell was operated at various operating temperatures with various anode gas compositions and air (no backpressure). In addition to the experimental results, a simple computational fluid dynamics model based on COMSOL Multiphysics {sup registered} 3.5a was used to support the observed behaviour during segmented measurements. The computational domain consisted of the cathode side gas channels and the porous media. All of the boundary conditions and gas properties were defined in a manner similar to the experimental investigations. Some of the theoretical results were compared to the experimental results and conclusions were drawn. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Modular design for narrow scintillating cells with MRS photodiodes in strong magnetic field for ILC detector

    Science.gov (United States)

    Beznosko, D.; Blazey, G.; Dyshkant, A.; Rykalin, V.; Schellpffer, J.; Zutshi, V.

    2006-08-01

    The experimental results for the narrow scintillating elements with effective area about 20 cm 2 are reported. The elements were formed from the single piece of scintillator and were read out via wavelength shifting (WLS) fibers with the Metal/Resistor/Semiconductor (MRS) photodiodes on both ends of each fiber. The count rates were obtained using radioactive source 90Sr, with threshold at about three photoelectrons in each channel and quad coincidences (double coincidences between sensors on each fiber and double coincidences between two neighboring fibers). The formation of the cells from the piece of scintillator by using grooves is discussed, and their performances were tested using the radioactive source by measuring the photomutiplier current using the same WLS fiber. Because effective cell area can be readily enlarged or reduced, this module may be used as an active element for calorimeter or muon system for the design of the future electron-positron linear collider detector. Experimental verification of the performance of the MRS photodiode in a strong magnetic field of 9 T, and the impact a magnet quench at 9.5 T are reported. The measurement method used is described. The results confirm the expectations that the MRS photodiode is insensitive to a strong magnetic field and therefore applicable to calorimetry in the presence of magnetic field. The overall result is of high importance for large multi-channel systems.

  6. Response Properties of a Newly Identified Tristratified Narrow Field Amacrine Cell in the Mouse Retina.

    Directory of Open Access Journals (Sweden)

    G S Newkirk

    Full Text Available Amacrine cells were targeted for whole cell recording using two-photon fluorescence microscopy in a transgenic mouse line in which the promoter for dopamine receptor 2 drove expression of green fluorescent protein in a narrow field tristratified amacrine cell (TNAC that had not been studied previously. Light evoked a multiphasic response that was the sum of hyperpolarizing and depolarization synaptic inputs consistent with distinct dendritic ramifications in the off and on sublamina of the inner plexiform layer. The amplitude and waveform of the response, which consisted of an initial brief hyperpolarization at light onset followed by recovery to a plateau potential close to dark resting potential and a hyperpolarizing response at the light offset varied little over an intensity range from 0.4 to ~10^6 Rh*/rod/s. This suggests that the cell functions as a differentiator that generates an output signal (a transient reduction in inhibitory input to downstream retina neurons that is proportional to the derivative of light input independent of its intensity. The underlying circuitry appears to consist of rod and cone driven on and off bipolar cells that provide direct excitatory input to the cell as well as to GABAergic amacrine cells that are synaptically coupled to TNAC. Canonical reagents that blocked excitatory (glutamatergic and inhibitory (GABA and glycine synaptic transmission had effects on responses to scotopic stimuli consistent with the rod driven component of the proposed circuit. However, responses evoked by photopic stimuli were paradoxical and could not be interpreted on the basis of conventional thinking about the neuropharmacology of synaptic interactions in the retina.

  7. Numerical Analysis of Novel Back Surface Field for High Efficiency Ultrathin CdTe Solar Cells

    Directory of Open Access Journals (Sweden)

    M. A. Matin

    2013-01-01

    Full Text Available This paper numerically explores the possibility of high efficiency, ultrathin, and stable CdTe cells with different back surface field (BSF using well accepted simulator AMPS-1D (analysis of microelectronics and photonic structures. A modified structure of CdTe based PV cell SnO2/Zn2SnO4/CdS/CdTe/BSF/BC has been proposed over reference structure SnO2/Zn2SnO4/CdS/CdTe/Cu. Both higher bandgap materials like ZnTe and Cu2Te and low bandgap materials like As2Te3 and Sb2Te3 have been used as BSF to reduce minority carrier recombination loss at the back contact in ultra-thin CdTe cells. In this analysis the highest conversion efficiency of CdTe based PV cell without BSF has been found to be around 17% using CdTe absorber thickness of 5 μm. However, the proposed structures with different BSF have shown acceptable efficiencies with an ultra-thin CdTe absorber of only 0.6 μm. The proposed structure with As2Te3 BSF showed the highest conversion efficiency of 20.8% ( V,  mA/cm2, and . Moreover, the proposed structures have shown improved stability in most extents, as it was found that the cells have relatively lower negative temperature coefficient. However, the cell with ZnTe BSF has shown better overall stability than other proposed cells with temperature coefficient (TC of −0.3%/°C.

  8. Occurrence of BOOP outside radiation field after radiation therapy for small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hamanishi, Tohru; Oida, Kazukiyo [Tenri Hospital, Nara (Japan); Morimatu, Takafumi (and others)

    2001-09-01

    We report a case of bronchiolitis obliterans organizing pneumonia (BOOP) that occurred outside the radiation field after radiation therapy for small cell lung cancer. A 74-year-old woman received chemotherapy and a total of 60 Gy of radiation therapy to the right hilum and mediastinum for small cell carcinoma of the suprahilar area of the right lung. Radiation pneumonitis developed within the radiation port 3 months after the completion of radiation therapy. She complained of cough and was admitted 7 months after completion of the radiation therapy. Chest radiography and computed tomography demonstrated peripheral alveolar opacities outside the radiation field on the side contralateral to that receiving the radiation therapy. Bronchoalveolar lavage showed that the total cell count was increased, with a markedly increased percentage of lymphocytes. Transbronchial lung biopsy revealed a histologic pattern consistent with BOOP. Treatment with corticosteroids resulted in rapid improvement of the symptoms and complete resolution of the radiographic abnormalities of the left lung. Although some cases of BOOP following radiation therapy for breast cancer have been reported, none of BOOP after radiation therapy for lung cancer have appeared in the literature. (author)

  9. Calcium signalling in human neutrophil cell lines is not affected by low-frequency electromagnetic fields.

    Science.gov (United States)

    Golbach, Lieke A; Philippi, John G M; Cuppen, Jan J M; Savelkoul, Huub F J; Verburg-van Kemenade, B M Lidy

    2015-09-01

    We are increasingly exposed to low-frequency electromagnetic fields (LF EMFs) by electrical devices and power lines, but if and how these fields interact with living cells remains a matter of debate. This study aimed to investigate the potential effect of LF EMF exposure on calcium signalling in neutrophils. In neutrophilic granulocytes, activation of G-protein coupled receptors leads to efflux of calcium from calcium stores and influx of extracellular calcium via specialised calcium channels. The cytoplasmic rise of calcium induces cytoskeleton rearrangements, modified gene expression patterns, and cell migration. If LF EMF modulates intracellular calcium signalling, this will influence cellular behaviour and may eventually lead to health problems. We found that calcium mobilisation upon chemotactic stimulation was not altered after a short 30 min or long-term LF EMF exposure in human neutrophil-like cell lines HL-60 or PLB-985. Neither of the two investigated wave forms (Immunent and 50 Hz sine wave) at three magnetic flux densities (5 μT, 300 μT, and 500 μT) altered calcium signalling in vitro. Gene-expression patterns of calcium-signalling related genes also did not show any significant changes after exposure. Furthermore, analysis of the phenotypical appearance of microvilli by scanning electron microscopy revealed no alterations induced by LF EMF exposure. The findings above indicate that exposure to 50 Hz sinusoidal or Immunent LF EMF will not affect calcium signalling in neutrophils in vitro.

  10. Lithium-Ion Battery Cell Cycling and Usage Analysis in a Heavy-Duty Truck Field Study

    OpenAIRE

    Pontus Svens; Mårten Behm; Göran Lindbergh

    2015-01-01

    This paper presents results from a field test performed on commercial power-optimized lithium-ion battery cells cycled on three heavy-duty trucks. The goal with this study was to age battery cells in a hybrid electric vehicle (HEV) environment and find suitable methods for identifying cell ageing. The battery cells were cycled on in-house developed equipment intended for testing on conventional vehicles by emulating an HEV environment. A hybrid strategy that allows battery usage to vary with...

  11. Lithium-Ion Battery Cell Cycling and Usage Analysis in a Heavy-Duty Truck Field Study

    OpenAIRE

    Pontus Svens; Mårten Behm; Göran Lindbergh

    2015-01-01

    This paper presents results from a field test performed on commercial power-optimized lithium-ion battery cells cycled on three heavy-duty trucks. The goal with this study was to age battery cells in a hybrid electric vehicle (HEV) environment and find suitable methods for identifying cell ageing. The battery cells were cycled on in-house developed equipment intended for testing on conventional vehicles by emulating an HEV environment. A hybrid strategy that allows battery usage to vary withi...

  12. Dark Skies, Bright Kids! Year 5

    Science.gov (United States)

    Prager, Brian; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Bittle, L.; Borish, H.; Burkhardt, A.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Graninger, D.; Lauck, T.; Liss, S.; Oza, A.; Peacock, S.; Romero, C.; Sokal, K. R.; Stierwalt, S.; Walker, L.; Wenger, T.; Zucker, C.

    2014-01-01

    Our public outreach group Dark Skies, Bright Kids! (DSBK) fosters science literacy in Virginia by bringing a hands-on approach to astronomy that engages children's natural excitement and curiosity. We are an entirely volunteer-run group based out of the Department of Astronomy at the University of Virginia and we enthusiastically utilize astronomy as a 'gateway science.' We create long-term relationships with students during an 8 to 10 week long, after-school astronomy club at under served elementary schools in neighboring counties, and we visited 3 different schools in 2013. Additionally, we organize and participate in science events throughout the community. The fifth year of DSBK was marked by surpassing 10,000 contact hours in Spring 2013 Semester and by ringing in the fall semester with our biggest, most successful star party to date. We hosted the Third Annual Central Virginia Star Party, free and open to the community to encourage families to enjoy astronomy together. Nearly four hundred people of all ages attended, double the number from previous years. Joining with local astronomical societies, we offered an enlightening and exciting night with resources rarely accessible to the public, such as an IR camera and a portable planetarium. With numerous telescopes pointed at the sky, and a beautifully clear night with views of the Milky Way, the International Space Station, and numerous meteors, the star party was a fantastic opportunity to introduce many of our guests to the natural wonders of our night sky and enjoy some of the darkest skies on the eastern seaboard.

  13. Dark Skies, Bright Kids! Year 3

    Science.gov (United States)

    Whelan, David G.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R. L.; Borish, J.; Corby, J. F.; Dorsey, G.; Gugliucci, N. E.; Prager, B. J.; Ries, P. A.; Romero, C. E.; Sokal, K. R.; Tang, X.; Walker, L. M.; Yang, A. J.; Zasowski, G.

    2012-01-01

    Dark Skies, Bright Kids! (DSBK) is a program that brings astronomy education to elementary schools throughout central Virginia. In a relaxed, out-of-classroom atmosphere, we are able to foster the innate curiosity that young students have about science and the world around them. We target schools that are under-served due to their rural locale or special needs students, demonstrating that science is a fun and creative process to a segment of the population that might not otherwise be exposed to astronomy. Families are included in the learning experience during semi-annual `star parties'. Since last January, we have expanded the breadth and depth of our educational capabilities. We have developed new programs for use in our digital planetarium. We held the first Central Virginia Star Party, providing an atmosphere where local children from multiple schools were able to share their love for astronomy. Local government and University officials were also invited so that they could experience our focused science outreach. Most recently, we have become part of Ivy Creek School's Club Day activities, bringing our program to a new segment of the elementary school system in Albemarle County: those that have `low-incidence' disabilities, requiring special attention. We continue to develop a curriculum for after-school programs that functions as either a series of one-time activities or several months of focused outreach at one school. Many of these activities are provided on our website, http://www.astro.virginia.edu/dsbk/, for the wider astronomical community, including the new planetarium work. We have extended our book project to include two bilingual astronomy books called `Snapshots of the Universe,' one in Spanish and English, the other in French and English. These books introduce young people to some of the many wonders of the Universe through art and captions developed by DSBK volunteers.

  14. Analysis of the effect of a 60 Hz AC field on histamine release by rat peritoneal mast cells.

    Science.gov (United States)

    Price, J A; Strattan, R D

    1998-01-01

    Reports have indicated effects of electromagnetic fields on inflammatory processes in vivo. To begin a systematic approach toward separating and examining the many components of such responses, we created and tested a temperature-controlled device to develop 5 mT 60 Hz magnetic fields for studies of the effects of fields on mast cells, a key component in acute inflammatory responses. Such fields have been reported to modulate cell activity, including changes in membrane function, in various systems. The magnetic field was generated using a solenoid and calibrated with an induction probe. Tests of mast cell function were determined by histamine release response to stimulation by compound 48/80, using both an "expose then test" and a "test during exposure" protocol. Aliquots not treated with 48/80 were used to evaluate field treatment effects on spontaneous histamine release. Freshly harvested rat peritoneal mast cells were exposed to the magnetic field for periods of 30 min to 2 h at 37 degrees C. They showed no significant degranulation during treatment, nor did they show reduced sensitivity to the degranulating agent 48/80. These observations are consistent with a model in which such processes are exclusively reflexive by the cells using field-independent membrane systems. This observation is very useful and was needed before examining longer term exposures in which gene expression in the cells might be influenced; this is the first such report of in vitro exposure of purified mast cells under these conditions and will further the study of the effects of electromagnetic fields on cell types active in acute inflammation.

  15. Microbial electricity generation in rice paddy fields: recent advances and perspectives in rhizosphere microbial fuel cells.

    Science.gov (United States)

    Kouzuma, Atsushi; Kaku, Nobuo; Watanabe, Kazuya

    2014-12-01

    Microbial fuel cells (MFCs) are devices that use living microbes for the conversion of organic matter into electricity. MFC systems can be applied to the generation of electricity at water/sediment interfaces in the environment, such as bay areas, wetlands, and rice paddy fields. Using these systems, electricity generation in paddy fields as high as ∼80 mW m(-2) (based on the projected anode area) has been demonstrated, and evidence suggests that rhizosphere microbes preferentially utilize organic exudates from rice roots for generating electricity. Phylogenetic and metagenomic analyses have been conducted to identify the microbial species and catabolic pathways that are involved in the conversion of root exudates into electricity, suggesting the importance of syntrophic interactions. In parallel, pot cultures of rice and other aquatic plants have been used for rhizosphere MFC experiments under controlled laboratory conditions. The findings from these studies have demonstrated the potential of electricity generation for mitigating methane emission from the rhizosphere. Notably, however, the presence of large amounts of organics in the rhizosphere drastically reduces the effect of electricity generation on methane production. Further studies are necessary to evaluate the potential of these systems for mitigating methane emission from rice paddy fields. We suggest that paddy-field MFCs represent a promising approach for harvesting latent energy of the natural world. PMID:25394406

  16. On the origin of the deviation from the first order kinetics in inactivation of microbial cells by pulsed electric fields

    CERN Document Server

    Lebovka, N I

    2003-01-01

    A computer model was developed for estimation of the kinetics of microbial inactivation by pulsed electric field. The model is based on the electroporation theory of individual membrane damage, where spherical cell geometry and distribution of cell sizes are assumed. The variation of microbial cell sizes was assumed to follow a statistical probability distribution of the Gaussian type. Surviving kinetics was approximated by Weibull equation. The dependencies of two Weibull parameters (shape textit{n} and time $tau $, respectively) versus electric field intensity E and width of cell diameters distribution was studied.

  17. The lowest spatial frequency channel determines brightness perception.

    Science.gov (United States)

    Perna, A; Morrone, M C

    2007-05-01

    This study investigates the role played by individual spatial scales in determining the apparent brightness of greyscale patterns. We measured the perceived difference in brightness across an edge in the presence of notch filtering and high-pass filtering for two stimulus configurations, one that elicits the perception of transparency and one that appears opaque. For both stimulus configurations, the apparent brightness of the surfaces delimited by the border decreased monotonically with progressive (ideal) high-pass filtering, with a critical cut-off at 1 c/deg. Using two octave ideal notch filtering, the maximum detrimental effect on apparent brightness was observed at about 1c/deg. Critical frequencies for apparent brightness did not vary with contrast, viewing distance, or surface size, suggesting that apparent brightness is determined by the channel tuned at 1 c/deg. Modelling the data with the local energy model [Morrone, M. C., & Burr, D. C. (1988). Feature detection in human vision: a phase dependent energy model. Proceedings of the Royal Society (London), B235, 221-245] at 1c/deg confirmed the suggestion that this channel mediates apparent brightness for both opaque and transparent borders, with no need for pooling or integration across spatial channels. PMID:17395237

  18. A novel design for a flow field configuration, of a direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Shou-Shing; Wu, Ho-Chieh; Her, Bing-Shyan [Department of Mechanical and Electro Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424 (China)

    2010-05-15

    We proposed and tested a new and novel arrangement for a direct methanol fuel cell consisting of one inlet for a methanol solution and four outlets for oxidant gas (air), in both the anode and cathode flow fields. It utilizes different operating temperatures of 40 C and 60 C, and different methanol solution flow rates of 5 ml min{sup -1}, 10 ml min{sup -1}, and 20 ml min{sup -1}. Test results indicate a significant reduction in produced CO{sub 2} gas in the anode flow channels and product water in the cathode flow channels; consequently, cell performance can be greatly improved. Furthermore, methanol crossover can also be avoided and reduced. (author)

  19. Numerical Analysis of Novel Back Surface Field for High Efficiency Ultrathin CdTe Solar Cells

    OpenAIRE

    M. A. Matin; Tomal, M. U.; Robin, A. M.; Amin, N.

    2013-01-01

    This paper numerically explores the possibility of high efficiency, ultrathin, and stable CdTe cells with different back surface field (BSF) using well accepted simulator AMPS-1D (analysis of microelectronics and photonic structures). A modified structure of CdTe based PV cell SnO2/Zn2SnO4/CdS/CdTe/BSF/BC has been proposed over reference structure SnO2/Zn2SnO4/CdS/CdTe/Cu. Both higher bandgap materials like ZnTe and Cu2Te and low bandgap materials like As2Te3 and Sb2Te3 have been used as BSF ...

  20. An efficient method for performance improvement of organometal halide perovskite solar cell via external electric field

    OpenAIRE

    Gong, Xiu; MA, HENG; JIANG, YU-RONG; Li, Meng; Wang, Zhao-Kui; Soga, Tetsuo

    2015-01-01

    An effective method, performed adding external electric field (EEF) on CH3NH3PbI3-xClx (OPIC) perovskite layer during the annealing process, is proposed to improve the performance of the solar cell. By harmonizing EEF direction with the hole/electron modified layer, a significant improvement on the short circuit current and fill factor is obtained. Using the simplest planar device, the largest positive EEF of 2.5*10^6 V/m makes PCE increase from 12.86 to 14.33, whose increment reaches 11.4% c...

  1. Strong synergy of heat and modulated electromagnetic field in tumor cell killing

    Energy Technology Data Exchange (ETDEWEB)

    Andocs, Gabor [Frederic Joliot Curie National Research Inst. for Radiobiology and Radiohygiene, Budapest (Hungary)]|[St. Istvan Univ., Budapest (Hungary). Dept. of Pharmacology and Toxicology; Renner, Helmut [Klinikum Nuernberg (Germany). Clinic of Radiooncology; Balogh, Lajos [Frederic Joliot Curie National Research Inst. for Radiobiology and Radiohygiene, Budapest (Hungary); Fonyad, Laszlo [Semmelweis Univ., Budapest (Hungary). 1. Dept. of of Pathology and Experimental Cancer Research; Jakab, Csaba [St. Istvan Univ., Budapest (Hungary). Dept. of Pathology; Szasz, Andras [St. Istvan Univ., Goedoelloe (Hungary). Biotechnics Dept.

    2009-02-15

    Hyperthermia is an emerging complementary method in radiooncology. Despite many positive studies and comprehensive reviews, the method is not widely accepted as a combination to radiotherapy. Modulated electrohyperthermia (mEHT; capacitive, electric field modulated, 13.56 MHz) has been used in clinical practice for almost 2 decades in Germany, Austria and Hungary. This in vivo study in nude mice xenograft tumors compares mEHT with 'classic' radiative hyperthermia (radHT). Nude mice were xenografted with HT29 human colorectal carcinoma cells. 28 mice in four groups with seven animals each and two tumors per animal (totally 56 tumors) were included in the present study: group 1 as untreated control; group 2 treated with radHT at 42 C; group 3 treated with mEHT at identical 42 C; group 4 treated with mEHT at 38 C (by intensively cooling down the tumor). 24 h after treatment, animals were sacrificed and the tumor cross sections studied by precise morphological methods for the respective relative amount of 'dead' tumor cells. The effect of mEHT established a double effect as a synergy between the purely thermal (temperature-dependent) and nonthermal (not directly temperature-dependent) effects. The solely thermal enhancement ratio (TER) of cell killing was shown to be 2.9. The field enhancement ratio (FER) at a constant temperature of 42 C was measured as 3.2. Their complex application significantly increased the therapeutic enhancement to 9.4. mEHT had a remarkable cancer cell-killing effect in a nude mice xenograft model. (orig.)

  2. Surface brightness fluctuation distances for nearby dwarf elliptical galaxies

    CERN Document Server

    Jerjen, H; Takalo, L; Coleman, M; Valtonen, M J; Jerjen, Helmut; Rekola, Rami; Takalo, Leo; Coleman, Matthew; Valtonen, Mauri

    2001-01-01

    We obtained B and R-band CCD images for the dwarf elliptical (dE) galaxies DDO44, UGC4998, KK98_77, DDO71, DDO113, and UGC7356 at the NOT. Using Fourier analysis technique we measure stellar R-band surface brightness fluctuations (SBFs) and magnitudes in 29 different fields of the galaxies. Independent tip of the red giant branch distances for DDO44, KK98_77, DDO71 are used to convert their set of apparent into absolute SBF magnitudes. The results are combined with the local (B-R) colours and compared with the (B-R)-\\bar{M}_R relation for mainly old, metal-poor stellar populations as predicted by Worthey's population synthesis models using Padova isochrones. While the colour dependency of the theoretical relation is confirmed by the empirical data, we find a systematic zero point offset between observations and theory in the sense that models are too faint by 0.13+-0.02 mag. Based on these findings we establish a new semiempirical calibration of the SBF method as distance indicator for dE galaxies with an est...

  3. The new world atlas of artificial night sky brightness

    CERN Document Server

    Falchi, Fabio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

    2016-01-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75{\\deg}N and 60{\\deg}S, 88% of Europe, and almost half of the United States experience light-polluted nights.

  4. An Ultraviolet imager to study bright UV sources

    CERN Document Server

    Mathew, Joice; Sarpotdar, Mayuresh; Sreejith, A G; Safonova, Margarita; Murthy, Jayant

    2016-01-01

    We have designed and developed a compact ultraviolet imaging payload to fly on a range of possible platforms such as high altitude balloon experiments, cubesats, space missions, etc. The primary science goals are to study the bright UV sources (mag < 10) and also to look for transients in the Near UV (200 - 300 nm) domain. Our first choice is to place this instrument on a spacecraft going to the Moon as part of the Indian entry into Google lunar X-Prize competition. The major constraints for the instrument are, it should be lightweight (< 2Kg), compact (length < 50cm) and cost effective. The instrument is an 80 mm diameter Cassegrain telescope with a field of view of around half a degree designated for UV imaging. In this paper we will discuss about the various science cases that can be performed by having observations with the instrument on different platforms. We will also describe the design, development and the current state of implementation of the instrument. This includes opto-mechanical and e...

  5. Temporal development of open-circuit bright photovoltaic solitons

    Institute of Scientific and Technical Information of China (English)

    Zhang Lei; Lu Ke-Qing; Zhang Mei-Zhi; Liu Xue-Ming; Zhang Yan-Peng

    2008-01-01

    This paper investigates the temporal behaviour of open-circuit bright photovoltaic spatial solitons by using numerical techniques. It shows that when the intensity ratio of the soliton, the ratio between the soliton peak intensity and the dark irradiance, is small, the quasi-steady-state soliton width decreases monotonically with the increase of τ, where τis the parameter correlated with the time, that when the intensity ratio of the soliton is big, the quasi-steady-state soliton width decreases with the increase of τ and then increases with τ and that the formation time of the steady-state solitons is not correlated with the intensity ratio of the soliton. It finds that the local nonlinear effect increases with the photovoltaic field, which behaves as that the width of soliton beams is small and the self-focusing quasi-period is short. On the other hand, we also discuss that both the time and the temperature have an effect on the beam bending.

  6. Physical characteristics of bright Class I methanol masers

    CERN Document Server

    Leurini, S; Walmsley, C M

    2016-01-01

    Class I CH$_3$OH masers trace interstellar shocks. They have received little attention mostly as a consequence of their low luminosities; this situation has changed recently and Class I masers are now routinely used as signposts of outflows. The recent detection of polarisation in Class I lines now makes it possible to obtain information on magnetic fields in shocks. We make use of newly calculated collisional rates to investigate the excitation of Class I masers and to reconcile their observed properties with model results. We performed LVG calculations with a plane-parallel slab geometry to compute the pump and loss rates which regulate the interactions of the different maser systems with the maser reservoir. We study the dependence of the pump rate, the loss rate, and the inversion efficiency of the pumping scheme of Class I masers on the physics of the gas. Bright Class I masers are mainly high-temperature high-density structures with maser emission measures corresponding to high CH$_3$OH abundances close...

  7. The new world atlas of artificial night sky brightness.

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

    2016-06-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights. PMID:27386582

  8. The new world atlas of artificial night sky brightness

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C. M.; Elvidge, Christopher D.; Baugh, Kimberly; Portnov, Boris A.; Rybnikova, Nataliya A.; Furgoni, Riccardo

    2016-01-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution—artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world’s land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights. PMID:27386582

  9. Kinematics of magnetic bright features in the solar photosphere

    CERN Document Server

    Jafarzadeh, Shahin; Cameron, R H; Barthol, P; Rodriguez, J Blanco; Iniesta, J C del Toro; Gandorfer, A; Gizon, L; Hirzberger, J; Knoelker, M; Pillet, V Martinez; Suarez, D Orozco; Riethmueller, T L; Schmidt, W; van Noort, M

    2016-01-01

    Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of the turbulent flows. We study the migration and dispersal of magnetic bright features (MBFs) in intergranular areas observed at high-spatial resolution with Sunrise/IMaX. We describe the flux dispersal of individual MBFs as a diffusion process whose parameters are computed for various areas in the quiet Sun and the vicinity of active regions from seeing-free data. We find that magnetic concentrations are best described as random walkers close to network areas (diffusion index, gamma=1.0), travelers with constant speeds over a supergranule (gamma=1.9-2.0), and decelerating movers in the vicinity of flux-emergence and/or within active regions (gamma=1.4-1.5). The three types of regions host MBFs with mean diffusion coefficients of 130 km^2/s, 80-90 km^2/s, and 25-70 km^2/s, respectively. The MBFs in these three types of regions are found to display a distinct ki...

  10. Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis.

    Science.gov (United States)

    Zhang, Yanjun; Clausmeyer, Jan; Babakinejad, Babak; López Córdoba, Ainara; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V; Korchev, Yuri

    2016-03-22

    Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements. PMID:26816294

  11. Extra-Low-Frequency Magnetic Fields alter Cancer Cells through Metabolic Restriction

    CERN Document Server

    Li, Ying

    2012-01-01

    Background: Biological effects of extra-low-frequency (ELF) magnetic fields (MF) have lacked a credible mechanism of interaction between MFs and living material. Objectives: Examine the effect of ELF-MFs on cancer cells. Methods: Five cancer cell lines were exposed to ELF-MFs within the range of 0.025 to 5 microT, and the cells were examined for karyotype changes after 6 days. Results: All cancer cells lines lost chromosomes from MF exposure, with a mostly flat dose-response. Constant MF exposures for three weeks allow a rising return to the baseline, unperturbed karyotypes. From this point, small MF increases or decreases are again capable of inducing karyotype contractions. Our data suggests that the karyotype contractions are caused by MF interference with mitochondria's ATP synthase (ATPS), compensated by the action of AMP-activated Protein Kinase (AMPK). The effects of MFs are similar to those of the ATPS inhibitor oligomycin. They are amplified by metformin, an AMPK stimulator, and attenuated by resisti...

  12. Induction of chondrogenic differentiation of human adipose-derived stem cells by low frequency electric field

    Science.gov (United States)

    Mardani, Mohammad; Roshankhah, Shiva; Hashemibeni, Batool; Salahshoor, Mohammadreza; Naghsh, Erfan; Esfandiari, Ebrahim

    2016-01-01

    Background: Since when the cartilage damage (e.g., with the osteoarthritis) it could not be repaired in the body, hence for its reconstruction needs cell therapy. For this purpose, adipose-derived stem cells (ADSCs) is one of the best cell sources because by the tissue engineering techniques it can be differentiated into chondrocytes. Chemical and physical inducers is required order to stem cells to chondrocytes differentiating. We have decided to define the role of electric field (EF) in inducing chondrogenesis process. Materials and Methods: A low frequency EF applied the ADSCs as a physical inducer for chondrogenesis in a 3D micromass culture system which ADSCs were extracted from subcutaneous abdominal adipose tissue. Also enzyme-linked immunosorbent assay, methyl thiazolyl tetrazolium, real time polymerase chain reaction and flowcytometry techniques were used for this study. Results: We found that the 20 minutes application of 1 kHz, 20 mv/cm EF leads to chondrogenesis in ADSCs. Although our results suggest that application of physical (EF) and chemical (transforming growth factor-β3) inducers at the same time, have best results in expression of collagen type II and SOX9 genes. It is also seen EF makes significant decreased expression of collagens type I and X genes. Conclusion: The low frequency EF can be a good motivator to promote chondrogenic differentiation of human ADSCs. PMID:27308269

  13. Outlook Bright for Computers in Chemistry.

    Science.gov (United States)

    Baum, Rudy M.

    1981-01-01

    Discusses the recent decision to close down the National Resource for Computation in Chemistry (NRCC), implications of that decision, and various alternatives in the field of computational chemistry. (CS)

  14. Sky Brightness Measurements at Haleakala, 1955-2002

    Science.gov (United States)

    LaBonte, Barry

    2003-11-01

    Measurements of the brightness of the clear daytime sky at Haleakala, Maui are presented for the interval 1955 through 2002. The observations are made near the direction of the Sun, where forward scattering off aerosols dominates the sky brightness. The Haleakala summit at 3054 m is normally above the inversion layer. The Haleakala sky is dark; the observed brightness per airmass has a median of 10 millionths of the solar disk and a mode of 5 millionths, with Rayleigh scattering contributing 1 millionth. There is no demonstrable long-term trend in the data.

  15. Biophysical Studies of Nanosecond Pulsed Electric Field Induced Cell Membrane Permeabilization

    Science.gov (United States)

    Wu, Yu-Hsuan

    Nanosecond megavolts-per-meter pulsed electric field (nsPEF) offers a non-invasive manipulation of intracellular organelles and functions of biological cells. Accordingly, nsPEF is a potential technique for biophysical research and cancer therapy, and is of growing interest. Although, the application of nsPEF has shown electroperturbation on cell plasma membranes and intracellular membranes as well, the mechanisms underlying the electropermeabilization are still not clear. In this thesis, we systematically study nsPEFs (5 and 30 ns) induced membrane permeability change in biological cell in-vitro with different pulse parameters. In Chapter 3, we investigate the nsPEF-induced intracellular membrane permeabilization of mitochondria which play key roles in activating apoptosis in mammalian cells. The results show the evidences of nsPEF-induced membrane permeability increase in mitochondria, and suggest that nsPEF is a potential technology for cancer cell ablation without delivery of drug or gene into cells. In Chapter 2, 4 and 6, we study the properties of nsPEF-induced plasma membrane permeabilization. In the beginning, the change of plasma membrane permeability is studied by uptake of YO-PRO-1 and propidium iodide, fluorescent dyes specifically used as indicators of plasma membrane permeabilization. However, the detection is limited by the fluorescent emission efficiency and detector capability. To increase the detection sensitivity, we later develop a method based on cell volume change due to regulation of osmotic balance that causes water and small ions transport through plasma membrane. We find that even a single 10 MV/m pulse of 5 ns duration produces measureable cell swelling. The results demonstrate that cell swelling is susceptible to nsPEF and can detect membrane permeabilization more easily and precisely than fluorescent dyes. We compare the effects of different pulse parameters (pulse duration, pulse number, electric field amplitude and pulse repetition

  16. High Brightness, High Average Current Injector Development at Cornell

    CERN Document Server

    Sinclair, C K

    2005-01-01

    Cornell University is constructing a 100 mA average current, high brightness electron injector for a planned Energy Recovery Linac (ERL) hard X-ray synchrotron radiation source. This injector will employ a very high voltage DC gun with a negative electron affinity photoemission cathode. Relatively long duration electron pulses from the photocathode will be drift bunched, and accelerated to 5-15 MeV with five two-cell, 1300 MHz superconducting cavities. The total beam power will be limited to 575 kW by the DC and RF power sources. A genetic algorithm based computational optimization of this injector has resulted in simulated rms normalized emittances of 0.1 mm-mrad at 80 pC/bunch, and 0.7 mm-mrad at 1 nC/bunch. The many technical issues and their design solutions will be discussed. Construction of the gun and the SRF cavities is well underway. The schedule for completion, and the planned measurements, will be presented.

  17. RF sputtered CdS/CdTe solar cells: Effects of magnetic field, RF power, target morphology, and substrate temperature

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A.D.; Shao, M.; Tabory, C.N.; Feng, Z.; Fischer, A.; Matulionis, I.; Bohn, R.G. [Univ. of Toledo, OH (United States). Dept. of Physics and Astronomy

    1994-12-31

    In this paper the authors present a study of the influence of substrate temperature, RF power, target erosion, and magnetic field configuration on RF sputtering of CdTe and CdS. These sputtering parameters are shown to affect deposition rate, film morphology, photoluminescence efficiency, and cell performance. The magnetic field shape and strength affects the charged particle flux on the growing film and appears to have a strong influence on the final cell performance.

  18. Effects of Magnetic Fluid Hyperthermia Induced by An Alternative Magnetic Field on Human Carcinoma A549 Cell in vitro

    Directory of Open Access Journals (Sweden)

    Guoqing WANG

    2011-03-01

    Full Text Available Background and objective Magnetic fluid hyperthermia (MFH is a method of heat therapy using nanometer techniques and hyperthermia. It has the advantage of high specificity of targeting. The aim of this study is to detect the effects of MFH induced by an alternating magnetic field on human being carcinoma A549 cells in vitro. Methods A human adenocarcinoma cell line A549 was cultured with various concentrations of ferroferric oxide (Fe3O4 magnetic fluid (1.5-6.0 mg/mL and exposed to an alternative magnetic field (AMF for 30 min. And then the optical density (OD of viable cell, cytotocixity index, growth curve of cells, morphologic changes of cell, cell cycle and aposptosis were measured. Results The proliferation of the A549 cells were remarkably inhibited, the OD value of viable cells decreased and cytotoxity index (CI increased; Apoptosis of the A549 cells were observed to have cell shrinkage, chromatin condensation, margination, unclear fragmentation and intact cell membrane by light and electron microscopy; The cells were inhibited in the stage S. Conclusion MFH induced by AMF could inhibit the proliferation, which promotes apoptosis and arrest at S stage of the A549 cells.

  19. Stimulation of osteogenic differentiation in human osteoprogenitor cells by pulsed electromagnetic fields: an in vitro study

    Directory of Open Access Journals (Sweden)

    Jansen Justus HW

    2010-08-01

    Full Text Available Abstract Background Although pulsed electromagnetic field (PEMF stimulation may be clinically beneficial during fracture healing and for a wide range of bone disorders, there is still debate on its working mechanism. Mesenchymal stem cells are likely mediators facilitating the observed clinical effects of PEMF. Here, we performed in vitro experiments to investigate the effect of PEMF stimulation on human bone marrow-derived stromal cell (BMSC metabolism and, specifically, whether PEMF can stimulate their osteogenic differentiation. Methods BMSCs derived from four different donors were cultured in osteogenic medium, with the PEMF treated group being continuously exposed to a 15 Hz, 1 Gauss EM field, consisting of 5-millisecond bursts with 5-microsecond pulses. On culture day 1, 5, 9, and 14, cells were collected for biochemical analysis (DNA amount, alkaline phosphatase activity, calcium deposition, expression of various osteoblast-relevant genes and activation of extracellular signal-regulated kinase (ERK signaling. Differences between treated and control groups were analyzed using the Wilcoxon signed rank test, and considered significant when p Results Biochemical analysis revealed significant, differentiation stage-dependent, PEMF-induced differences: PEMF increased mineralization at day 9 and 14, without altering alkaline phosphatase activity. Cell proliferation, as measured by DNA amounts, was not affected by PEMF until day 14. Here, DNA content stagnated in PEMF treated group, resulting in less DNA compared to control. Quantitative RT-PCR revealed that during early culture, up to day 9, PEMF treatment increased mRNA levels of bone morphogenetic protein 2, transforming growth factor-beta 1, osteoprotegerin, matrix metalloproteinase-1 and -3, osteocalcin, and bone sialoprotein. In contrast, receptor activator of NF-κB ligand expression was primarily stimulated on day 14. ERK1/2 phosphorylation was not affected by PEMF stimulation

  20. The Use of Solar Cell in Ground Water Irrigation to Support Agricultural Cultivation in Rainfed Field

    Directory of Open Access Journals (Sweden)

    Delvi Yanti

    2016-02-01

    Full Text Available This research aims at developing the use of solar cell to water the ground water irrigation in order to support agricultural cultivation in rain-fed field. The location of this research was agricultural land (ricefield in Singkarak village, X Koto Singkarak sub-district, Solok district. This research was conducted with the design and technical test of ground water irrigation with solar cell, the analysis of irrigation water demand with crop-wat and the analysis of financial feasibility. The result of analysis showed that the potential of solar energy in Singkarak village could be used to activate the water pump of irrigation. The result of measurement showed that battery which its capacity was 12 V and 100 Ah needed four hours to be charged by five units of 50 Wp panel PV. Battery as the source of power was able to activate water pump of 125 Watt for 7,52 hours and mean debit that was able to be pumped is 17,45 litre/minute. From 24 periods of plantation time planned in rain-fed field, there were only three periods of plantation that the operational hours of their water pumps were able to be covered by the battery namely January 2, February 2, and November 2. Based on the result of financial analysis, these three periods of plantation were financially feasible in their implementation because the value of B/C ratio > 1 and NPV > 0.

  1. Toward Intraoperative Detection of Disseminated Tumor Cells in Lymph Nodes with Silicon Nanowire Field Effect Transistors.

    Science.gov (United States)

    Tran, Duy P; Winter, Marnie A; Wolfrum, Bernhard; Stockmann, Regina; Yang, Chih-Tsung; Pourhassan-Moghaddam, Mohammad; Offenhäusser, Andreas; Thierry, Benjamin

    2016-02-23

    Within an hour, as little as one disseminated tumor cell (DTC) per lymph node can be quantitatively detected using an intraoperative biosensing platform based on silicon nanowire field-effect transistors (SiNW FET). It is also demonstrated that the integrated biosensing platform is able to detect the presence of circulating tumor cells (CTCs) in the blood of colorectal cancer patients. The presence of DTCs in lymph nodes and CTCs in peripheral blood is highly significant as it is strongly associated with poor patient prognosis. The SiNW FET sensing platform out-performed in both sensitivity and rapidity not only the current standard method based on pathological examination of tissue sections but also the emerging clinical gold standard based on molecular assays. The possibility to achieve accurate and highly sensitive analysis of the presence of DTCs in the lymphatics within the surgery time frame has the potential to spare cancer patients from an unnecessary secondary surgery, leading to reduced patient morbidity, improving their psychological wellbeing and reducing time spent in hospital. This study demonstrates the potential of nanoscale field-effect technology in clinical cancer diagnostics. PMID:26859618

  2. Quantum bright solitons in a quasi-one-dimensional optical lattice

    Science.gov (United States)

    Barbiero, Luca; Salasnich, Luca

    2014-06-01

    We study a quasi-one-dimensional attractive Bose gas confined in an optical lattice with a superimposed harmonic potential by analyzing the one-dimensional Bose-Hubbard Hamiltonian of the system. Starting from the three-dimensional many-body quantum Hamiltonian, we derive strong inequalities involving the transverse degrees of freedom under which the one-dimensional Bose-Hubbard Hamiltonian can be safely used. To have a reliable description of the one-dimensional ground state, which we call a quantum bright soliton, we use the density-matrix-renormalization-group (DMRG) technique. By comparing DMRG results with mean-field (MF) ones, we find that beyond-mean-field effects become relevant by increasing the attraction between bosons or by decreasing the frequency of the harmonic confinement. In particular, we find that, contrary to the MF predictions based on the discrete nonlinear Schrödinger equation, average density profiles of quantum bright solitons are not shape-invariant. We also use the time-evolving-block-decimation method to investigate the dynamical properties of bright solitons when the frequency of the harmonic potential is suddenly increased. This quantum quench induces a breathing mode whose period crucially depends on the final strength of the superimposed harmonic confinement.

  3. Predicting electroporation of cells in an inhomogeneous electric field based on mathematical modeling and experimental CHO-cell permeabilization to propidium iodide determination.

    Science.gov (United States)

    Dermol, Janja; Miklavčič, Damijan

    2014-12-01

    High voltage electric pulses cause electroporation of the cell membrane. Consequently, flow of the molecules across the membrane increases. In our study we investigated possibility to predict the percentage of the electroporated cells in an inhomogeneous electric field on the basis of the experimental results obtained when cells were exposed to a homogeneous electric field. We compared and evaluated different mathematical models previously suggested by other authors for interpolation of the results (symmetric sigmoid, asymmetric sigmoid, hyperbolic tangent and Gompertz curve). We investigated the density of the cells and observed that it has the most significant effect on the electroporation of the cells while all four of the mathematical models yielded similar results. We were able to predict electroporation of cells exposed to an inhomogeneous electric field based on mathematical modeling and using mathematical formulations of electroporation probability obtained experimentally using exposure to the homogeneous field of the same density of cells. Models describing cell electroporation probability can be useful for development and presentation of treatment planning for electrochemotherapy and non-thermal irreversible electroporation.

  4. Brookhaven Lab physicists Edward Beebe and Alexander Pikin win 'Brightness Award' for achievement in ion source physics and technology

    CERN Document Server

    2003-01-01

    "Edward Beebe and Alexander Pikin, physicists at the U.S. Department of Energy's Brookhaven National Laboratory, have been awarded the Ion Source Prize, known as the "Brightness Award," which recognizes and encourages innovative and significant recent achievements in the fields of ion source physics and technology" (1 page).

  5. Visible Color and Photometry of Bright Materials on Vesta

    Science.gov (United States)

    Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

    2012-01-01

    The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

  6. Bright Prospect for the Polyester Industrial Filament Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Some large companies from Americaand Europe have constructed plantsin China or established long-termstable cooperation relationship withChinese enterprises. A bright devel-opment prospect has therefore beenbrought to the polyester industrial fila-ment sector in China.

  7. SMEX03 SSM/I Brightness Temperature Data, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  8. SMEX03 SSM/I Brightness Temperature Data, Georgia

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  9. Ultra High Brightness/Low Cost Fiber Coupled Packaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The focus of the proposed effort is maximizing the brightness of fiber coupled laser diode pump sources at a minimum cost. The specific innovation proposed is to...

  10. Ablation effects of noninvasive radiofrequency field-induced hyperthermia on liver cancer cells

    Directory of Open Access Journals (Sweden)

    Kaiyun Chen

    2016-05-01

    Full Text Available To have in-depth analysis of clinical ablation effect of noninvasive radiofrequency field-induced hyperthermia on liver cancer cells, this paper collected liver cancer patients’ treatment information from 10 hospitals during January 2010 and December 2011, from which 1050 cases of patients were randomly selected as study object of observation group who underwent noninvasive radiofrequency field-induced hyperthermia treatment; in addition, 500 cases of liver cancer patients were randomly selected as study object of control group who underwent clinical surgical treatment. After treatment was completed, three years of return visit were done, survival rates of the two groups of patients after 1 year, 2 years, and 3 years were compared, and clinical effects of radiofrequency ablation of liver cancer were evaluated. Zoom results show that the two groups are similar in terms of survival rate, and the difference is without statistical significance. 125 patients in observation group had varying degrees of adverse reactions, while 253 patients in control group had adverse reactions. There was difference between groups P < 0.05, with significant statistical significance. It can be concluded that radiofrequency ablation of liver cancer is more secure. Therefore, the results of this study fully demonstrate that liver cancer treatment with noninvasive radiofrequency field-induced hyperthermia is with safety effect and satisfactory survival rate, thus with relatively high clinical value in clinical practice.

  11. Theoretical prediction of a bright pattern of reflective flakes in a precessing sphere

    International Nuclear Information System (INIS)

    Non-trivial bright patterns of reflective flakes recently observed experimentally and numerically in a precessing sphere are reproduced theoretically by the use of a small flat-plate model of flakes with diffusion effects of Brownian motion and the asymptotic velocity field in the double limit of large Reynolds numbers and small Poincaré numbers. It is shown that what is visualized by flakes is not the local flow field but the overall contribution of the velocity gradient, induced by the conical shear layers, over the whole orbit of flakes. It is suggested that Brownian motion plays a significant role to the orientation distribution of flakes. (paper)

  12. Beam dynamics in an initial part of a high Brightness electron linac

    CERN Document Server

    Ayzatsky, M I; Dovbnya-Kushnir, V A

    2001-01-01

    The paper is focused on problems of obtained a bright electron beam in a system that includes a grid-controlled electron gun,a klystron type type subharmonical buncher, a standing wave fundamental buncher with increasing accelerating field and a short travelling wave accelerating section. Beam focusing is provided by a longitudinal solenoidal magnetic field.It was shown that the proposed system can provide electron bunches with a peak current more than 100 A and normalized r.m.s. emittance no more than phi centre dot mm centre dot mrad.

  13. Dressed-state resonant coupling between bright and dark spins in diamond.

    Science.gov (United States)

    Belthangady, C; Bar-Gill, N; Pham, L M; Arai, K; Le Sage, D; Cappellaro, P; Walsworth, R L

    2013-04-12

    Under ambient conditions, spin impurities in solid-state systems are found in thermally mixed states and are optically "dark"; i.e., the spin states cannot be optically controlled. Nitrogen-vacancy (NV) centers in diamond are an exception in that the electronic spin states are "bright"; i.e., they can be polarized by optical pumping, coherently manipulated with spin-resonance techniques, and read out optically, all at room temperature. Here we demonstrate a scheme to resonantly couple bright NV electronic spins to dark substitutional-nitrogen (P1) electronic spins by dressing their spin states with oscillating magnetic fields. This resonant coupling mechanism can be used to transfer spin polarization from NV spins to nearby dark spins and could be used to cool a mesoscopic bath of dark spins to near-zero temperature, thus providing a resource for quantum information and sensing, and aiding studies of quantum effects in many-body spin systems. PMID:25167312

  14. Studying the lay of the land : views and experiences of professionals in the translational pluripotent stem cell field

    NARCIS (Netherlands)

    Habets, Michelle G J L; van Delden, Johannes J M; Bredenoord, Annelien L

    2016-01-01

    AIM: The inherent uncertainty of first-in-human trials, combined with the technical complexity of pluripotent stem cells (PSCs), makes early phase PSC studies ethically challenging. Conducting parallel bioethics research based on experiences and views of professionals in the stem cell field is there

  15. Analytically derived conversion of spectral band radiance to brightness temperature

    Energy Technology Data Exchange (ETDEWEB)

    Berk, Alexander [Spectral Sciences, Inc., 44th Avenue, Burlington, MA 01803 (United States)], E-mail: lex@spectral.com

    2008-05-15

    Simple analytic expressions for brightness temperature have been derived in terms of band response function spectral moments. Accuracy measures are also derived. Application of these formulas to GOES-12 Sounder thermal infrared bands produces brightness temperature residuals between -5.0 and 2.5 mK for a 150-400 K temperature range. The magnitude of residuals for the five ASTER Radiometer thermal infrared bands over the same temperature range is less than 0.22 mK.

  16. Night Sky Brightness and Light Pollution in Comunidad de Madrid

    OpenAIRE

    Zamorano Calvo, Jaime; Sánchez de Miguel, Alejandro; Gómez Castaño, José; Ocaña González, Francisco; Gallego Maestro, Jesús; Pila Díez, Berenice; Nievas Rosillo, Miguel; Tapia Ayuga, Carlos; Fernández Domínguez, Alberto; Pascual Ramírez, Sergio

    2013-01-01

    Preliminary results of a study of the night sky background brightness around the city of Madrid using Sky Quality Meter (SQM) photometers are presented. Data-retrieval methodology includes an automatic procedure to measure from a moving vehicle which allows to speed up the data gathering. The night sky brightness, an astronomical quality parameter that accounts for luminous flux from the sky, is closely related with the light pollution. The map with the spatial distribution of the night s...

  17. Supercontinuum generation with bright and dark solitons in optical fibers

    CERN Document Server

    Milián, Carles; Kudlinski, Alexandre; Skryabin, Dmitry V

    2016-01-01

    We study numerically and experimentally supercontinuum generation in optical fibers with dark and bright solitons simultaneously contributing into the spectral broadening and dispersive wave generation. We report a novel type of weak trapped radiation arising due to interaction of bright solitons with the dark soliton background. This radiation expresses itself as two pulses with the continuously shifting spectra constituting the short and long wavelength limits of the continuum. Our theoretical and experimental results are in good agreement.

  18. Facial Expression Recognition using Entropy and Brightness Features

    OpenAIRE

    Khan, Rizwan Ahmed; Meyer, Alexandre; Konik, Hubert; Bouakaz, Saïda

    2011-01-01

    International audience This paper proposes a novel framework for universal facial expression recognition. The framework is based on two sets of features extracted from the face image: entropy and brightness. First, saliency maps are obtained by state-of-the-art saliency detection algorithm i.e. "frequencytuned salient region detection". Then only localized salient facial regions from saliency maps are processed to extract entropy and brightness features. To validate the performance of sali...

  19. Millimeter-wave brightness temperatures of military vehicles

    Science.gov (United States)

    Nemarich, Joseph; Cassidy, Thomas W.; Shiner, R.; Agravante, Hiroshi H.; Dixon, David; Moffa, Philip; Quon, Bill H.; Yujiri, Larry; Dahlstrom, R.

    1999-07-01

    Millimeter wave (MMW) radiometers operating at 97 and 140 GHz were used to obtain passive MMW images and brightness temperatures of military vehicles at various altitudes and depression angles. The line-scanning radiometer system used for the measurements is described, and several passive MMW images are presented. The upper-bound MMW brightness temperatures of a number of different types of vehicles in an open area were determined and shown to have similar values at various depression angles.

  20. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    OpenAIRE

    Karachentsev, I. D.; Riepe, P.; Zilch, T.; Blauensteiner, M.; Elvov, M.; Hochleitner, P.; Hubl, B.; Kerschhuber, G.; Küppers, S.; Neyer, F.; Pölzl, R.; Remmel, P.; Schneider, O.; Sparenberg, R.; Trulson, U.

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their abs...