WorldWideScience

Sample records for bright field cell

  1. 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)

  2. 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.

  3. Fast automated yeast cell counting algorithm using bright-field and fluorescence microscopic images

    OpenAIRE

    Hong, Dongpyo; Lee, Gwanghee; Jung, Neon Cheol; Jeon, Moongu

    2013-01-01

    Background The faithful determination of the concentration and viability of yeast cells is important for biological research as well as industry. To this end, it is important to develop an automated cell counting algorithm that can provide not only fast but also accurate and precise measurement of yeast cells. Results With the proposed method, we measured the precision of yeast cell measurements by using 0%, 25%, 50%, 75% and 100% viability samples. As a result, the actual viability measured ...

  4. 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...

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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

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

    Science.gov (United States)

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

    2013-01-01

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

  12. The statistical distribution of magnetic field strength in G-band bright points

    CERN Document Server

    Criscuoli, Serena

    2013-01-01

    G-band bright points are small-sized features characterized by high photometric contrast. Theoretical investigations indicate that these features have associated magnetic field strengths between 1-2 kG. Results from observations instead lead to contradictory results, indicating magnetic fields of only kG strength in some and including hG strengths in others. In order to understand the differences between measurements reported in the literature, and to reconcile them with results from theory, we analyze the distribution of magnetic field strength of G-band bright features identified on synthetic images of the solar photosphere, and its sensitivity to observational and methodological effects. We investigate the dependence of magnetic field strength distributions of G-band bright points identified in 3D magnetohydrodynamic simulations on feature selection method, data sampling, alignment and spatial resolution. The distribution of magnetic field strength of G-band bright features shows two peaks, one at about 1....

  13. 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

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

    Science.gov (United States)

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

    2013-06-01

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

  15. 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.

  16. 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...

  17. Modeling of emissive properties and electron-optical parameters of ultrahigh brightness pointed field electron sources

    International Nuclear Information System (INIS)

    Full text: lt is well known that high brightness field electron sources are widely used in various electron probe analytical instruments and technological units. The reduced brightness (B) of electron probes formed by electron-optical systems (EOS) of those instruments and units may reach very high values (up to ∼ 108 A/(m2 sr V)). However, the known traditional applications do not exhaust the potentials of field (and thermal field) emission sources. Specifically, of considerable interest are the prospects for creating ultrahigh brightness electron beams. Forming electron beams with B >> 108 A/(m2 sr V) would make feasible development of a new class of electron probe instruments which will help to solve a number of current scientific and technological problems including those of micromechanics and microelectromechanics. Note that the main functional feature of such instruments is the possibility of in-depth analysis and surface modification of condensed matter exposed to an electronic beam whose power density (P) exceeds a threshold level necessary for the initiation of electron ablation. Since P ∞ B ∞ Bs, where Bs is the brightness of the electron source of EOS, the purpose of the present work was to study physical and technological aspects of the development of ultrahigh brightness pointed field electron sources. To solve the problem stated, one should first find an answer to the basic question, namely, whether Bs levels reached so far are maximum possible (or approach the physical limit for Bs) and, if not, how can we increase Bs of field emitters? To answer the above question, we studied emissive and electron-optical characteristics of various emitters in various modes of field emission, which include the following characteristic types of processes: Extended Schottky Emission, Thermal Field Emission (TFE), and finally ('pure') Field Emission. The numerical modeling of the electrostatic field potential distribution for a conventional electrode geometry in

  18. 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.

  19. High brightness field emission from printed carbon nanotubes in an S-band microwave gun

    Science.gov (United States)

    Wang, Qilong; Li, Xiangkun; Di, Yusong; Yu, Cairu; Zhang, Xiaobing; Li, Ming; Lei, Wei

    2016-02-01

    Printed carbon nanotubes (CNTs) were applied as cold cathode and placed into an S-band microwave gun operating at 2856 MHz with the pulse duration of 2.8 μs. High brightness field emission was demonstrated and the current density achieves the value more than 4.2 A/cm2. The emittance of field emission beam is calculated to be nearly 21 μm based on the beam profile of emission electrons monitored via yttrium aluminum garnet screen. The infrared image of printed CNTs confirms that the emitters in the center contributed more electrons and the heat generated during the large current density field emission. The results in the paper imply that randomly distributed printed CNTs have the potential to be applied as the high brightness electron sources for free electron lasers.

  20. 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.

  1. 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

  2. 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 ...

  3. 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.

  4. 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...

  5. 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...

  6. 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...

  7. Motion and Magnetic Flux Changes of Coronal Bright Points Relative to Supergranular Cell Boundaries

    Science.gov (United States)

    Yousefzadeh, M.; Safari, H.; Attie, R.; Alipour, N.

    2016-01-01

    To calculate the magnetic flux and the horizontal movement of coronal bright points (CBPs) in relation to supergranular cell boundaries, the time series of the SDO/HMI visible-light continuum images and SDO/AIA EUV images for 13 February 2011 have been studied. The supergranular lanes were detected in HMI continuum images using the automatic supergranular cell recognition method. The automatic identification and tracking method was applied for detecting the CBPs in AIA 193 Å images. By applying the ball-tracking method on HMI continuum images, the underlying flow fields were determined. By using the velocity fields and the automatic supergranular cell recognition method, the lanes and boundaries were detected. The locations of CBPs were projected on the photospheric co-spatial and co-temporal images. We found that about 90 % of the locations of CBPs correspond to the lane of the supergranular cell boundaries (network CBPs or NCBPs) of which about 40 % of them appeared at junctions. The remaining 10 % appeared within the supergranular regions (internetwork CBPs or INCBPs). The horizontal velocities for NCBPs and INCBPs were about 1.6±0.1 km s^{-1} and 1.7±0.1 km s^{-1}, respectively. Using the magnetic field extrapolation, we were able to detect the bipoles underlying CBPs, and we studied their magnetic evolution. The orientation of CBPs observed in the 171, 193, and 211 Å images and the orientation of their magnetic bipoles are positively correlated. For out of 50 INCBPs, 54 % showed cancellation, 32 % emergence, and 12 % complex flux changes. Out of 90 NCBPs, 60 % presented cancellation, 20 % showed emergence, and 20 % showed complex flux changes.

  8. 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, Jr.; 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.

  9. 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...

  10. 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. PMID:26440760

  11. Ageing is associated with a decline in peripheral blood CD56bright NK cells

    Directory of Open Access Journals (Sweden)

    Nayak Laxman

    2006-11-01

    Full Text Available Abstract Background Natural killer (NK cells are cytotoxic lymphocytes that lack CD3 and express variable levels of CD16, CD56 and CD57. In recent years NK cells have been categorised into two major groups based on the level of CD56 expression. This phenotypic classification correlates with functional activity as CD56bright NK cells are the major cytokine producing subset whereas CD56dim NK cells exhibit greater cytotoxic activity. Previous studies have revealed a reduction in total NK cell numbers in association with ageing and this study sought to determine the potential influence of ageing on the number of NK cell subsets within peripheral blood. Results The number of NK (CD56+CD3- cells within peripheral blood did not change with increasing age. The number of CD56dim NK cells also remained stable with ageing. In contrast the absolute number of CD56bright NK cells within peripheral blood declined by 48% with ageing from a mean of 15.6/μl in individuals aged 20–40 years to 8.1/μl in those aged 60+ years (p = 0.0004. Conclusion The number of CD56bright NK cells within peripheral blood declines with age. As this population plays a central role in cytokine secretion during the innate immune response this decline may contribute to impaired immune regulation in elderly individuals

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

    Science.gov (United States)

    Suran, Swathi; Bharadwaj, Krishna; Raghavan, Srinivasan; Varma, Manoj M.

    2016-04-01

    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 specific ions in the solution. It is anticipated that this technique will find use in applications ranging from single-nanoparticles resolved sensing to studying nanoscale fluid-solid interface phenomena.

  13. 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. PMID:27150100

  14. 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...

  15. Motion Vector Field Estimation Using Brightness Constancy Assumption and Epipolar Geometry Constraint

    Science.gov (United States)

    Hosseinyalamdary, S.; Yilmaz, A.

    2014-11-01

    In most Photogrammetry and computer vision tasks, finding the corresponding points among images is required. Among many, the Lucas-Kanade optical flow estimation has been employed for tracking interest points as well as motion vector field estimation. This paper uses the IMU measurements to reconstruct the epipolar geometry and it integrates the epipolar geometry constraint with the brightness constancy assumption in the Lucas-Kanade method. The proposed method has been tested using the KITTI dataset. The results show the improvement in motion vector field estimation in comparison to the Lucas-Kanade optical flow estimation. The same approach has been used in the KLT tracker and it has been shown that using epipolar geometry constraint can improve the KLT tracker. It is recommended that the epipolar geometry constraint is used in advanced variational optical flow estimation methods.

  16. 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

  17. Engineering the fano resonance and electromagnetically induced transparency in near-field coupled bright and dark metamaterial

    International Nuclear Information System (INIS)

    Near-field coupling between orthogonally twisted bright and dark mode resonances gives rise to sharp Fano-like resonances and electromagnetically induced transparency. We demonstrate that by varying the orientation of the near-field coupled bright and dark metamolecule with respect to the incident electric field, the shape and linewidth of the coupling induced transparency could be easily engineered. This particular aspect of the near-field coupled metamolecules could lead to engineered slow-light devices, narrow bandpass filters and ultrasensitive sensors. (paper)

  18. On the Relationship Between G-Band Bright Point Dynamics and Their Magnetic Field Strengths

    Science.gov (United States)

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

    2016-04-01

    G-band bright points (GBPs) are regarded as good manifestations of magnetic flux concentrations. We aim to investigate the relation 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 automatically identified and tracked in the G-band images, 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 analyzed the dynamics of each group of GBPs. 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 complex motion paths. This suggests that magnetic elements showing weaker magnetic field strengths move faster and farther along straighter paths, while stronger elements move more slowly in more erratic paths within a smaller region. The dynamic behaviors of GBPs with different longitudinal magnetic field strengths can be explained by that the stronger flux concentrations withstand the convective flows much better than weaker ones.

  19. On the Relationship Between G-Band Bright Point Dynamics and Their Magnetic Field Strengths

    Science.gov (United States)

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

    2016-04-01

    G-band bright points (GBPs) are regarded as good manifestations of magnetic flux concentrations. We aim to investigate the relation 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 automatically identified and tracked in the G-band images, 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 analyzed the dynamics of each group of GBPs. 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 complex motion paths. This suggests that magnetic elements showing weaker magnetic field strengths move faster and farther along straighter paths, while stronger elements move more slowly in more erratic paths within a smaller region. The dynamic behaviors of GBPs with different longitudinal magnetic field strengths can be explained by that the stronger flux concentrations withstand the convective flows much better than weaker ones.

  20. 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...

  1. Bright z ~ 3 Lyman break galaxies in deep wide field surveys

    Science.gov (United States)

    Bian, Fuyan

    In my thesis I investigate the luminous z ˜ 3 Lyman break galaxies in deep wide field surveys. In the first part of the thesis, I use the LBT/LUCIFER to observe a lensed high-redshift star-forming galaxy (J0900+2234) at z = 2.03. With the high S/N near-IR spectroscopic observations, I reveal the detailed physical properties of this high-redshift galaxy, including SFR, metallicity, dust extinction, dynamical mass, and electron number density. In the second part of the thesis, I select a large sample of LBGs at z ˜ 3 from our new LBT Bootes field survey, and study the bright end luminosity function (LF), stellar mass function (SMF) and clustering properties of bright LBGs (1L* < L < 2.5L*). Together with other LF and SMF measurements, the evolution of LF and SMF can be well described by continuously rising star formation history model. Using the clustering measurements in this work and other works, a tight relation between the average host galaxy halo mass and the galaxy star formation rate is found, which can be interpreted as arising from cold flow accretion. The relation also suggests that the cosmic star formation efficiency is about 5%-20% of the total cold flow mass. This cosmic star formation efficiency does not evolve with redshift (from z ˜ 5 to z ˜ 3), hosting dark matter halo mass (1011 -- 1013 M⊙ ), or galaxy luminosity (from 0.3L* to 3L* ). In the third and fourth parts, with the spectroscopic follow-up observations of the bright LBGs, I establish a sample of spectroscopically-confirmed ultraluminous LBGs (ULBGs) in NOAO Boo¨tes field. With this new ULBG sample, the rest-frame UV LF of LBG at M1700A = -23.0 was measured for the first time. I find that the ULBGs have larger outflow velocity, broader Lyalpha emission and ISM absorption line profiles, and more prominent C IV P-Cygni profile. This profile may imply a top-heavy IMF in these ULBGs. The ULBGs have larger stellar mass and SFR, but smaller dust extinction than the typical L* LBGs at z ˜ 2

  2. Ageing is associated with a decline in peripheral blood CD56bright NK cells

    OpenAIRE

    Nayak Laxman; Chan Y L Tracey; Khan Naeem; Chidrawar Shivani M; Moss Paul AH

    2006-01-01

    Abstract Background Natural killer (NK) cells are cytotoxic lymphocytes that lack CD3 and express variable levels of CD16, CD56 and CD57. In recent years NK cells have been categorised into two major groups based on the level of CD56 expression. This phenotypic classification correlates with functional activity as CD56bright NK cells are the major cytokine producing subset whereas CD56dim NK cells exhibit greater cytotoxic activity. Previous studies have revealed a reduction in total NK cell ...

  3. 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.

  4. Relation between the Sunrise photospheric magnetic field and the Ca II H bright features

    Science.gov (United States)

    Jafarzadeh, Shahin; Hirzberger, J.; Feller, A.; Lagg, A.; Solanki, S. K.; Pietarila, A.; Danilovic, S.; Riethmueller, T.; Barthol, P.; Berkefeld, T.; Gandorfer, A.; Knülker, M.; Martínez Pillet, V.; Schmidt, W.; Schüssler, M.; Title, A.

    Recent observations from the Sunrise balloon-borne solar telescope have enabled us to reach an unprecedented high spatial resolution on the solar surface with the near-ultraviolet photo-spheric and chromospheric images as well as the magnetograms. We use these high resolution observations to investigate the structure of the solar upper photosphere and lower chromosphere as well as their temporal evolutions. We study the relation between the inter-granular Ca II 397 nm bright structures in images obtained by the Sunrise Filter Imager (SuFI) and their corresponding photospheric vector magnetic field computed from the Imaging Magnetogram eXperiment (IMaX) observations. The targets under study are in a quiet Sun region and close to disc-centre.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. Theory of bright-field scanning transmission electron microscopy for tomography

    International Nuclear Information System (INIS)

    Radiation transport theory is applied to electron microscopy of samples composed of one or more materials. The theory, originally due to Goudsmit and Saunderson, assumes only elastic scattering and an amorphous medium dominated by atomic interactions. For samples composed of a single material, the theory yields reasonable parameter-free agreement with experimental data taken from the literature for the multiple scattering of 300-keV electrons through aluminum foils up to 25 μm thick. For thin films, the theory gives a validity condition for Beer's law. For thick films, a variant of Moliere's theory [V. G. Moliere, Z. Naturforschg. 3a, 78 (1948)] of multiple scattering leads to a form for the bright-field signal for foils in the multiple-scattering regime. The signal varies as [t ln(e1-2γt/τ)]-1 where t is the path length of the beam, τ is the mean free path for elastic scattering, and γ is Euler's constant. The Goudsmit-Saunderson solution interpolates numerically between these two limits. For samples with multiple materials, elemental sensitivity is developed through the angular dependence of the scattering. From the elastic scattering cross sections of the first 92 elements, a singular-value decomposition of a vector space spanned by the elastic scattering cross sections minus a delta function shows that there is a dominant common mode, with composition-dependent corrections of about 2%. A mathematically correct reconstruction procedure beyond 2% accuracy requires the acquisition of the bright-field signal as a function of the scattering angle. Tomographic reconstructions are carried out for three singular vectors of a sample problem with four elements Cr, Cu, Zr, and Te. The three reconstructions are presented jointly as a color image; all four elements are clearly identifiable throughout the image

  10. 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

  11. 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...

  12. 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.

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

    Science.gov (United States)

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

    2010-03-01

    Nanotubes and fullerene-like nanoparticles of various inorganic layered compounds have been studied extensively in recent years. Their characterisation on the atomic scale has proven essential for progress in synthesis as well as for the theoretical modelling of their physical properties. We show that with electron tomography it is possible to achieve a reliable reconstruction of the 3D structure of nested WS(2) or MoS(2) fullerene-like and nanotube structures with sub-nanometre resolution using electron microscopes that are not aberration-corrected. Model-based simulations were used to identify imaging parameters, under which structural features such as the shell structure can be retained in the tomogram reconstructed from bright-field micrographs. The isolation of a particle out of an agglomerate for the analysis of a single structure and its interconnection with other particles is facilitated through the tomograms. The internal structure of the layers within the particle alongside the shape and content of its internal void are reconstructed. The tomographic reconstruction yields insights regarding the growth process as well as structural defects, such as non-continuous layers, which relate to the lubrication properties. PMID:20644827

  14. 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

  15. 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.

  16. 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

  17. A laboratory 8 keV transmission full-field x-ray microscope with a polycapillary as condenser for bright and dark field imaging

    Energy Technology Data Exchange (ETDEWEB)

    Baumbach, S., E-mail: baumbach@rheinahrcampus.de; Wilhein, T. [Institute for X-Optics, University of Applied Sciences Koblenz, RheinAhrCampus Remagen, Joseph-Rovan-Allee 2, D-53424 Remagen (Germany); Kanngießer, B.; Malzer, W. [Institute for Optics and Atomic Physics, Technical University of Berlin, Hardenbergstrasse 36, D-10623 Berlin (Germany); Stiel, H. [Max-Born-Institute, Max-Born-Strasse 2A, D-12489 Berlin (Germany)

    2015-08-15

    This article introduces a laboratory setup of a transmission full-field x-ray microscope at 8 keV photon energy. The microscope operates in bright and dark field imaging mode with a maximum field of view of 50 μm. Since the illumination geometry determines whether the sample is illuminated homogeneously and moreover, if different imaging methods can be applied, the condenser optic is one of the most significant parts. With a new type of x-ray condenser, a polycapillary optic, we realized bright field imaging and for the first time dark field imaging at 8 keV photon energy in a laboratory setup. A detector limited spatial resolution of 210 nm is measured on x-ray images of Siemens star test patterns.

  18. 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

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

    OpenAIRE

    Farahnaz Mardanian; Moones Kazeroonizadeh; Bahman Rashidi

    2015-01-01

    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 ...

  20. 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.

  1. 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.

  2. 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...

  3. 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...

  4. 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.

  5. 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

  6. 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.

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

    OpenAIRE

    Broek, van den, W.; 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 health informatics is introduced. A compact state-of-the-art introduction on stress (reduction) is provided. A pragmatic solution for the pressing societal problem of illness due to chronic stress is pr...

  8. 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).

  9. Comparative quantification of umbilical cord blood CD34+ and CD34+ bright cells using the ProCount™-BD and ISHAGE protocols

    Directory of Open Access Journals (Sweden)

    P. Pranke

    2006-07-01

    Full Text Available The total number of CD34+ cells is the most relevant clinical parameter when selecting human umbilical cord blood (HUCB for transplantation. The objective of the present study was to compare the two most commonly used CD34+ cell quantification methods (ISHAGE protocol and ProCount™ - BD and analyze the CD34+ bright cells whose 7-amino actinomycin D (7AAD analysis suggests are apoptotic or dead cells. Twenty-six HUCB samples obtained at the Placental Blood Program of New York Blood Center were evaluated. The absolute numbers of CD34+ cells evaluated by the ISHAGE (with exclusion of 7AAD+ cells and ProCount™ (with exclusion of CD34+ bright cells were determined. Using the ISHAGE protocol we found 35.6 ± 19.4 CD34+ cells/µL and with the ProCount™ method we found 36.6 ± 23.2 CD34+ cells/µL. With the ProCount™ method, CD34+ bright cell counts were 9.3 ± 8.2 cells/µL. CD34+ bright and regular cells were individually analyzed by the ISHAGE protocol. Only about 1.8% of the bright CD34+ cells are alive, whereas a small part (19.0% is undergoing apoptosis and most of them (79.2% are dead cells. Our study showed that the two methods produced similar results and that 7AAD is important to exclude CD34 bright cells. These results will be of value to assist in the correct counting of CD34+ cells and to choose the best HUCB unit for transplantation, i.e., the unit with the greatest number of potentially viable stem cells for the reconstitution of bone marrow. This increases the likelihood of success of the transplant and, therefore, the survival of the patient.

  10. 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...

  11. 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

  12. 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.

  13. 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.

  14. 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...

  15. 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...

  16. 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...

  17. Rationale and design for PACE: patients with intermittent claudication injected with ALDH bright cells.

    Science.gov (United States)

    Perin, Emerson C; Murphy, Michael; Cooke, John P; Moyé, Lem; Henry, Timothy D; Bettencourt, Judy; Gahremanpour, Amir; Leeper, Nicholas; Anderson, R David; Hiatt, William R; Lima, Joao A; Venkatesh, Bharath; Sayre, Shelly L; Vojvodic, Rachel W; Taylor, Doris A; Ebert, Ray F; Hirsch, Alan T

    2014-11-01

    Peripheral artery disease (PAD) is recognized as a public health issue because of its prevalence, functional limitations, and increased risk of systemic ischemic events. Current treatments for claudication, the primary symptom in patients with PAD, have limitations. Cells identified using cytosolic enzyme aldehyde dehydrogenase (ALDH) may benefit patients with severe PAD but has not been studied in patients with claudication. PACE is a randomized, double-blind, placebo-controlled clinical trial conducted by the Cardiovascular Cell Therapy Research Network to assess the safety and efficacy of autologous bone marrow-derived ALDH(br) cells delivered by direct intramuscular injections in 80 patients with symptom-limiting intermittent claudication. Eligible patients will have a significant stenosis or occlusion of infrainguinal arteries and a resting ankle-brachial index less than 0.90 and will be randomized 1:1 to cell or placebo treatment with a 1-year follow-up. The primary end points are the change in peak walking time and leg collateral arterial anatomy, calf muscle blood flow, and tissue perfusion as determined by magnetic resonance imaging at 6 months compared with baseline. The latter 3 measurements are new physiologic lower extremity tissue perfusion and PAD imaging-based end points that may help to quantify the biologic and mechanistic effects of cell therapy. This trial will collect important mechanistic and clinical information on the safety and efficacy of ALDH(br) cells in patients with claudication and provide valuable insight into the utility of advanced magnetic resonance imaging end points. PMID:25440794

  18. 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.

  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. Loss of CCR7 expression on CD56(bright NK cells is associated with a CD56(dimCD16⁺ NK cell-like phenotype and correlates with HIV viral load.

    Directory of Open Access Journals (Sweden)

    Henoch S Hong

    Full Text Available NK cells are pivotal sentinels of the innate immune system and distinct subpopulations in peripheral blood have been described. A number of studies addressed HIV-induced alterations of NK cell phenotype and functionality mainly focusing on CD56(dimCD16⁺ and CD56⁻CD16⁺ NK cells. However, the impact of HIV-infection on CD56(bright NK cells is less well understood. Here we report a rise of CD56(bright NK cells in HIV-infected individuals, which lack CCR7-expression and strongly correlate with HIV viral load. CCR7⁻CD56(bright NK cells were characterized by increased cytolytic potential, higher activation states and a more differentiated phenotype. These cells thus acquired a number of features of CD56(dimCD16⁺ NK cells. Furthermore, CD56(bright NK cells from HIV patients exhibited higher degranulation levels compared to uninfected individuals. Thus, chronic HIV-infection is associated with a phenotypic and functional shift of CD56(bright NK cells, which provides a novel aspect of HIV-associated pathogenesis within the NK cell compartment.

  1. 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...... cofactor concentrations. Possible uses and limitations of this method for plant cell research are discussed....... of NAD(P)(+). After the addition of cofactors and substrates, activities of cytosolic as well as mitochondrial respiratory enzymes could be directly determined inside the permeabilized cells. However, at an AlaM concentration at which the cytoplasmic enzymes were maximally accessible, the vacuole...

  2. Migration of CD8+ T Cells into the Central Nervous System Gives Rise to Highly Potent Anti-HIV CD4dimCD8bright T Cells in a Wnt Signaling-Dependent Manner.

    Science.gov (United States)

    Richards, Maureen H; Narasipura, Srinivas D; Seaton, Melanie S; Lutgen, Victoria; Al-Harthi, Lena

    2016-01-01

    The role of CD8(+) T cells in HIV control in the brain and the consequences of such control are unclear. Approximately 3% of peripheral CD8(+) T cells dimly express CD4 on their surface. This population is known as CD4(dim)CD8(bright) T cells. We evaluated the role of CD4(dim)CD8(bright) and CD8 single positive T cells in HIV-infected brain using NOD/SCID/IL-2rcγ(-/-) mice reconstituted with human PBMCs (NSG-huPBMC). All three T cell populations (CD4 single positive, CD8 single positive, and CD4(dim)CD8(bright)) were found in NSG-huPBMC mouse brain within 2 wk of infection. Wnts secreted from astrocytes induced CD4(dim)CD8(bright) T cells by 2-fold in vitro. Injection of highly purified CD8 single positive T cells into mouse brain induced CD4(dim)CD8(bright) T cells by 10-fold, which were proliferative and exhibited a terminally differentiated effector memory phenotype. Brain CD4(dim)CD8(bright) T cells from HIV-infected mice exhibited anti-HIV-specific responses, as demonstrated by induction of CD107ab post exposure to HIV peptide-loaded targets. Further, higher frequency of CD4(dim)CD8(bright) T cells (R = -0.62; p ≤ 0.001), but not CD8 single positive T cells (R = -0.24; p ≤ 0.27), negatively correlated with HIV gag mRNA transcripts in HIV-infected NSG-huPBMC brain. Together, these studies indicate that single positive CD8(+) T cells entering the CNS during HIV infection can give rise to CD4(dim)CD8(bright) T cells, likely through a Wnt signaling-dependent manner, and that these cells are associated with potent anti-HIV control in the CNS. Thus, CD4(dim)CD8(bright) T cells are capable of HIV control in the CNS and may offer protection against HIV-associated neurocognitive disorders. PMID:26582945

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. A bright z=5.2 lensed submillimeter galaxy in the field of Abell 773: HLSJ091828.6+514223

    CERN Document Server

    Combes, F; Rawle, T D; Egami, E; Boone, F; Smail, I; Richard, J; Ivison, R J; Gurwell, M; Casey, C M; Omont, A; Alba, A Berciano; Dessauges-Zavadsky, M; Edge, A C; Fazio, G G; Kneib, J-P; Okabe, N; Pello, R; Perez-Gonzalez, P G; Schaerer, D; Smith, G P; Swinbank, A M; van der Werf, P

    2012-01-01

    During our Herschel Lensing Survey (HLS) of massive galaxy clusters, we have discovered an exceptionally bright submillimeter source, behind the z=0.22 cluster Abell 773, which appears to be a strongly lensed submillimeter galaxy (SMG) at z=5.2429. This source is unusual compared to most other lensed sources discovered by Herschel so far, both for its higher submm flux (\\sim 200mJy at 500micron) and its high redshift. The dominant lens is a foreground z=0.63 galaxy, not the cluster itself. From the continuum detected, we derive a far-infrared luminosity of LFIR= 1.1E14 /\\mu Lo, where \\mu is the magnification factor, likely \\sim 11. We report here the redshift identification through CO lines with the IRAM-30m, and the analysis of the gas excitation, based on CO(7-6), CO(6-5), CO(5-4) detected at IRAM and the CO(2-1) detected with the EVLA. All lines decompose in a wide and strong red component, and a narrower and weaker blue component, 540\\kms apart. Assuming the local ULIRG CO-to-H2 conversion ratio, the H2 m...

  8. 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

    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...... 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...... 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...

  9. 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...

  10. Effect of ATP sulfurylase overexpression in bright yellow 2 tobacco cells: regulation of ATP sulfurylase and SO4(-2) transport activities

    International Nuclear Information System (INIS)

    To determine if the ATP sulfurylase reaction is a regulatory step for the SO4(2-)-assimilation pathway in plants, an Arabidopsis thaliana ATP sulfurylase cDNA, APS2, was fused to the 355 promoter of the cauliflower mosaic virus and introduced by Agrobacterium tumefaciens-mediated transformation into isolated Bright Yellow 2 tobacco (Nicotiana tabacum) cells. The ATP sulfurylase activity in transgenic cells was 8-fold that in control cells, and was correlated with the expression of a specific polypeptide revealed by western analysis using an anti-ATP sulfurylase antibody. The molecular mass of this polypeptide agreed with that for the overexpressed mature protein. ATP sulfurylase overexpression had no effect on [35S]SO4(2-) influx or ATP sulfurylase activity regulation by S availability, except that ATP sulfurylase activity variations in response to S starvation in transgenic cells were 8 times higher than in the wild type. There were also no differences in cell growth or sensitivity to SeO4(2-) (a toxic SO4(2-) analog) between transgenic and wild-type cells. We propose that in Bright Yellow 2 tobacco cells, the ATP sulfurylase derepression by S deficiency may involve a posttranscriptional mechanism, and that the ATP sulfurylase abundance is not limiting for cell metabolism

  11. 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

  12. 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.

  13. OPTICAL-FAINT, FAR-INFRARED-BRIGHT HERSCHEL SOURCES IN THE CANDELS FIELDS: ULTRA-LUMINOUS INFRARED GALAXIES AT z > 1 AND THE EFFECT OF SOURCE BLENDING

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Haojing; Stefanon, Mauro; Ma, Zhiyuan [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Willner, S. P.; Ashby, Matthew L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Somerville, Rachel [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Davé, Romeel [University of the Western Cape, 7535 Bellville, Cape Town (South Africa); Pérez-González, Pablo G. [Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Cava, Antonio [Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Versoix (Switzerland); Wiklind, Tommy [Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago (Chile); Kocevski, Dale [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Rafelski, Marc [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Kartaltepe, Jeyhan [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Cooray, Asantha [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Koekemoer, Anton M.; Grogin, Norman A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2014-07-01

    The Herschel very wide field surveys have charted hundreds of square degrees in multiple far-IR (FIR) bands. While the Sloan Digital Sky Survey (SDSS) is currently the best resource for optical counterpart identifications over such wide areas, it does not detect a large number of Herschel FIR sources and leaves their nature undetermined. As a test case, we studied seven ''SDSS-invisible'', very bright 250 μm sources (S {sub 250} > 55 mJy) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields where we have a rich multi-wavelength data set. We took a new approach to decompose the FIR sources, using the near-IR or the optical images directly for position priors. This is an improvement over the previous decomposition efforts where the priors are from mid-IR data that still suffer from the problem of source blending. We found that in most cases the single Herschel sources are made of multiple components that are not necessarily at the same redshifts. Our decomposition succeeded in identifying and extracting their major contributors. We show that these are all ultra-luminous infrared galaxies at z ∼ 1-2 whose high L {sub IR} is mainly due to dust-obscured star formation. Most of them would not be selected as submillimeter galaxies. They all have complicated morphologies indicative of mergers or violent instability, and their stellar populations are heterogeneous in terms of stellar masses, ages, and formation histories. Their current ultra-luminous infrared galaxy phases are of various degrees of importance in their stellar mass assembly. Our practice provides a promising starting point for developing an automatic routine to reliably study bright Herschel sources.

  14. OPTICAL-FAINT, FAR-INFRARED-BRIGHT HERSCHEL SOURCES IN THE CANDELS FIELDS: ULTRA-LUMINOUS INFRARED GALAXIES AT z > 1 AND THE EFFECT OF SOURCE BLENDING

    International Nuclear Information System (INIS)

    The Herschel very wide field surveys have charted hundreds of square degrees in multiple far-IR (FIR) bands. While the Sloan Digital Sky Survey (SDSS) is currently the best resource for optical counterpart identifications over such wide areas, it does not detect a large number of Herschel FIR sources and leaves their nature undetermined. As a test case, we studied seven ''SDSS-invisible'', very bright 250 μm sources (S 250 > 55 mJy) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields where we have a rich multi-wavelength data set. We took a new approach to decompose the FIR sources, using the near-IR or the optical images directly for position priors. This is an improvement over the previous decomposition efforts where the priors are from mid-IR data that still suffer from the problem of source blending. We found that in most cases the single Herschel sources are made of multiple components that are not necessarily at the same redshifts. Our decomposition succeeded in identifying and extracting their major contributors. We show that these are all ultra-luminous infrared galaxies at z ∼ 1-2 whose high L IR is mainly due to dust-obscured star formation. Most of them would not be selected as submillimeter galaxies. They all have complicated morphologies indicative of mergers or violent instability, and their stellar populations are heterogeneous in terms of stellar masses, ages, and formation histories. Their current ultra-luminous infrared galaxy phases are of various degrees of importance in their stellar mass assembly. Our practice provides a promising starting point for developing an automatic routine to reliably study bright Herschel sources

  15. PROBING THE IGM/GALAXY CONNECTION. IV. THE LCO/WFCCD GALAXY SURVEY OF 20 FIELDS SURROUNDING UV-BRIGHT QUASARS

    International Nuclear Information System (INIS)

    We publish the survey for galaxies in 20 fields containing ultraviolet bright quasars (with zem ∼ 0.1-0.5) that can be used to study the association between galaxies and absorption systems from the low-z intergalactic medium (IGM). The survey is magnitude limited (R ∼ 19.5 mag) and highly complete out to 10' from the quasar in each field. It was designed to detect dwarf galaxies (L ∼ 0.1L*) at an impact parameter ρ ∼ 1 Mpc (z = 0.1) from a quasar. The complete sample (all 20 fields) includes R-band photometry for 84,718 sources and confirmed redshifts for 2800 sources. This includes 1198 galaxies with 0.005 em - 0.01) at a median redshift of 0.18, which may associated with IGM absorption lines. All of the imaging was acquired with cameras on the Swope 40'' telescope and the spectra were obtained via slit mask observations using the WFCCD spectrograph on the Dupont 100'' telescope at Las Campanas Observatory. This paper describes the data reduction, imaging analysis, photometry, and spectral analysis of the survey. We tabulate the principal measurements for all sources in each field and provide the spectroscopic data set online.

  16. 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.

  17. Computer simulation on spatial resolution of X-ray bright-field imaging by dynamical diffraction theory for a Laue-case crystal analyzer

    International Nuclear Information System (INIS)

    Recently, dark-field imaging (DFI) and bright-field imaging (BFI) have been proposed and applied to visualize X-ray refraction effects yielded in biomedical objects. In order to clarify the spatial resolution due to a crystal analyzer in Laue geometry, a program based on the Takagi-Taupin equation was modified to be used for carrying out simulations to evaluate the spatial resolution of images coming into a Laue angular analyzer (LAA). The calculation was done with a perfect plane wave for diffraction wave-fields, which corresponded to BFI, under the conditions of 35 keV and a diffraction index 440 for a 2100 μm thick LAA. As a result, the spatial resolution along the g-vector direction showed approximately 37.5 μm. 126 μm-thick LAA showed a spatial resolution better than 3.1 μm under the conditions of 13.7 keV and a diffraction index 220.

  18. 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.

  19. 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

  20. Optical-faint, Far-infrared-bright Herschel Sources in the CANDELS Fields: Ultra-Luminous Infrared Galaxies at z>1 and the Effect of Source Blending

    CERN Document Server

    Yan, Haojing; Ma, Zhiyuan; Willner, Steven; Somerville, Rachel; Ashby, Matthew; Dave, Romeel; Perez-Gonzalez, Pablo G; Cava, Antonio; Wiklind, Tommy; Kocevski, Dale; Rafelski, Marc; Kartaltepe, Jeyhan; Cooray, Asantha

    2013-01-01

    Optical counterpart identification is a critical link in maximizing the science returns of the Herschel very wide-field survey data. Currently, the Sloan Digital Sky Survey (SDSS) is the best resource for optical counterpart identifications over such wide areas. However a large number of very bright FIR sources are not detected in the SDSS, and their true nature remains to be determined. Using the public HerMES data, we studied seven such sources that are within the CANDELS fields. To deal with the source blending problem, we used the near-IR or the optical images directly for position priors and decomposed these FIR sources. This new appraoch is an improvement over the previous decomposition efforts where the position priors are derived from the mid-IR data that still suffer from the source blending problem in the first place, and can be applied to the regions where the mid-IR data are not available. We found that in most cases the single Herschel sources are made of multiple components that may or may not b...

  1. The influence of brightness on functional assessment by mferg: a study on scaffolds used in retinal cell transplantation in pigs.

    Science.gov (United States)

    Christiansen, A T; Kiilgaard, J F; Smith, M; Ejstrup, R; Wnek, G E; Prause, J U; Young, M J; Klassen, H; Kaplan, H; La Cour, M

    2012-01-01

    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. PMID:22550501

  2. 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...

  3. 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...

  4. Electric field control of the cell orientation

    Science.gov (United States)

    Westman, Christopher; Sabirianov, Renat

    2008-03-01

    Many physiological processes depend on the response of biological cells to external forces. The natural electric field at a wound controls the orientation of the cell and its division.[1] We model the cell as an elongated elliptical particle with given Young's modulus with surface charge distribution in the external electric field. Using this simple theoretical model that includes the forces due to electrostatics and the elasticity of cells, we calculated analytically the response of the cell orientation and its dynamics in the presence of time varying electric field. The calculations reflect many experimentally observed features. Our model predicts the response of the cellular orientation to a sinusoidally varying applied electric field as a function of frequency similar to recent stress-induced effects.[2] *Bing Song, Min Zhao, John V. Forrester, and Colin D. McCaig, ``Electrical cues regulate the orientation and frequency of cell division and the rate of wound healing in vivo'', PNAS 2002, vol. 99 , 13577-13582. *R. De, A. Zemel, and S.A. Safran, ``Dynamics of cell orientation'', Nature Physics 2007, vol.3, 655.

  5. 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...

  6. 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

  7. 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.

  8. BrightFocus Foundation

    Science.gov (United States)

    ... size: A A Contrast En Español Donate BrightFocus Foundation Alzheimer’s Disease Research Macular Degeneration Research National Glaucoma ... Bovenkamp, Ph.D., Scientific Program Officer for BrightFocus Foundation, about the basic science and therapeutic research the ...

  9. 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...

  10. 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.

  11. 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.

  12. 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

  13. Helmholtz bright and boundary solitons

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. 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...

  16. 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 ...

  17. 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...

  18. 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

  19. Flow-Driven Cell Migration under External Electric Fields

    Science.gov (United States)

    Li, Yizeng; Mori, Yoichiro; Sun, Sean X.

    2015-12-01

    Electric fields influence many aspects of cell physiology, including various forms of cell migration. Many cells are sensitive to electric fields, and they can migrate toward a cathode or an anode, depending on the cell type. In this Letter, we examine an actomyosin-independent mode of cell migration under electrical fields. Our theory considers a one-dimensional cell with water and ionic fluxes at the cell boundary. Water fluxes through the membrane are governed by the osmotic pressure difference across the cell membrane. Fluxes of cations and anions across the cell membrane are determined by the properties of the ion channels as well as the external electric field. Results show that without actin polymerization and myosin contraction, electric fields can also drive cell migration, even when the cell is not polarized. The direction of migration with respect to the electric field direction is influenced by the properties of ion channels, and are cell-type dependent.

  20. Improving brightness and photostability of green and red fluorescent proteins for live cell imaging and FRET reporting.

    Science.gov (United States)

    Bajar, Bryce T; Wang, Emily S; Lam, Amy J; Kim, Bongjae B; Jacobs, Conor L; Howe, Elizabeth S; Davidson, Michael W; Lin, Michael Z; Chu, Jun

    2016-01-01

    Many genetically encoded biosensors use Förster resonance energy transfer (FRET) to dynamically report biomolecular activities. While pairs of cyan and yellow fluorescent proteins (FPs) are most commonly used as FRET partner fluorophores, respectively, green and red FPs offer distinct advantages for FRET, such as greater spectral separation, less phototoxicity, and lower autofluorescence. We previously developed the green-red FRET pair Clover and mRuby2, which improves responsiveness in intramolecular FRET reporters with different designs. Here we report the engineering of brighter and more photostable variants, mClover3 and mRuby3. mClover3 improves photostability by 60% and mRuby3 by 200% over the previous generation of fluorophores. Notably, mRuby3 is also 35% brighter than mRuby2, making it both the brightest and most photostable monomeric red FP yet characterized. Furthermore, we developed a standardized methodology for assessing FP performance in mammalian cells as stand-alone markers and as FRET partners. We found that mClover3 or mRuby3 expression in mammalian cells provides the highest fluorescence signals of all jellyfish GFP or coral RFP derivatives, respectively. Finally, using mClover3 and mRuby3, we engineered an improved version of the CaMKIIα reporter Camuiα with a larger response amplitude. PMID:26879144

  1. High Brightness Test Stand

    International Nuclear Information System (INIS)

    The High Brightness Test Stand is a 2 MeV, less than or equal to 10 kA electron accelerator module. This accelerator module, designed as an upgrade prototype for the Advanced Test Accelerator (ATA), combines solid state nonlinear magnetic drives with state-of-the-art induction linac technology. The facility serves a dual role, as it not only provides a test bed for this new technology, but is used to develop high brightness electron optics. We will both further describe the accelerator, as well as present some of the preliminary electron optics measurements

  2. 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.

  3. 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.

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

    International Nuclear Information System (INIS)

    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

  5. Selection effects in the bivariate brightness distribution for spiral galaxies

    International Nuclear Information System (INIS)

    The joint distribution of total luminosity and characteristic surface brightness (the bivariate brightness distribution) is investigated for a complete sample of spiral galaxies in the Virgo cluster. The influence of selection and physical limits of various kinds on the apparent distribution are detailed. While the distribution of surface brightness for bright galaxies may be genuinely fairly narrow, faint galaxies exist right across the (quite small) range of accessible surface brightnesses so no statement can be made about the true extent of the distribution. The lack of high surface brightness bright galaxies in the Virgo sample relative to an overall RC2 sample (mostly field galaxies) supports the contention that the star-formation rate is reduced in the inner region of the cluster for environmental reasons. (author)

  6. 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

  7. 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.

  8. A Magnetic Bright Point Case Study

    Czech Academy of Sciences Publication Activity Database

    Utz, D.; Jurčák, Jan; Bellot Rubio, L.; del Toro Iniesta, J.C.; Thonhofer, S.; Hanslmeier, A.; Veronig, A.; Muller, R.; Lemmerer, B.

    2013-01-01

    Roč. 37, č. 2 (2013), s. 459-470. ISSN 1845-8319. [Hvar Astrophysical Colloquium /12./. Hvar, 03.09.2012-07.09.2012] R&D Projects: GA MŠk(CZ) MEB061109 Institutional support: RVO:67985815 Keywords : solar magnetic field * magnetic bright points * sunrise/IMaX Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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...

  15. High brightness electron sources

    International Nuclear Information System (INIS)

    High energy physics accelerators and free electron lasers put increased demands on the electron beam sources. This paper describes the present research on attaining intense bright electron beams using photoinjectors. Recent results from the experimental programs will be given. The performance advantages and difficulties presently faced by researchers will be discussed, and the following topics will be covered. Progress has been made in photocathode materials, both in lifetime and quantum efficiency. Cesium telluride has demonstrated significantly longer lifetimes than cesium antimonide at 10-8 torr. However, the laser system is more difficult because cesium telluride requires quadrupled YLF instead of the doubled YLF required for cesium antimonide. The difficulty in using photoinjectors is primarily the drive laser, in particular the amplitude stability. Finally, emittance measurements of photoinjector systems can be complicated by the non-thermal nature of the electron beam. An example of the difficulty in measuring beam emittance is given

  16. 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

  17. 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

  18. 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.

  19. 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

  20. Phase-field model for collective cell migration

    Science.gov (United States)

    Najem, Sara; Grant, Martin

    2016-05-01

    We construct a phase-field model for collective cell migration based on a Ginzburg-Landau free-energy formulation. We model adhesion, surface tension, repulsion, coattraction, and polarization, enabling us to follow the cells' morphologies and the effect of their membranes fluctuations on collective motion. We were able to measure the tissue surface tension as a function of the individual cell cortical tension and adhesion and identify a density threshold for cell-sheet formation.

  1. Recent star formation in the inner Galactic Bulge seen by ISOGAL. I - Classification of bright mid-IR sources in a test field

    CERN Document Server

    Schuller, F; Glass, I S; Omont, A; Price, S D; Schultheis, M

    2006-01-01

    Context: The stellar populations in the central region of the Galaxy are poorly known because of the high visual extinction and very great source density in this direction. Aims: To use recent infrared surveys for studying the dusty stellar objects in this region. Methods: We analyse the content of a 20x20 arcmin^2 field centred at (l,b)=(-0.27,-0.06) observed at 7 and 15 microns as part of the ISOGAL survey. These ISO observations are more than an order of magnitude better in sensitivity and spatial resolution than the IRAS observations. The sources are cross-associated with other catalogues to identify various types of objects. We then derive criteria to distinguish young objects from post-main sequence stars. Results: We find that a sample of about 50 young stellar objects and ultra-compact HII regions emerges, out of a population of evolved AGB stars. We demonstrate that the sources colours and spatial extents, as they appear in the ISOGAL catalogue, possibly complemented with MSX photometry at 21 microns...

  2. 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

  3. 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.

  4. 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.

  5. Investigation of back surface fields effect on bifacial solar cells

    Science.gov (United States)

    Sepeai, Suhaila; Sulaiman, M. Y.; Sopian, Kamaruzzaman; Zaidi, Saleem H.

    2012-11-01

    A bifacial solar cell, in contrast with a conventional monofacial solar cell, produces photo-generated current from both front and back sides. Bifacial solar cell is an attractive candidate for enhancing photovoltaic (PV) market competitiveness as well as supporting the current efforts to increase efficiency and lower material costs. This paper reports on the fabrication of bifacial solar cells using phosphorus-oxytrichloride (POCl3) emitter formation on p-type, nanotextured silicon (Si) wafer. Backside surface field was formed through Al-diffusion using conventional screen-printing process. Bifacial solar cells with a structure of n+pp+ with and without back surface field (BSF) were fabricated in which silicon nitride (SiN) anti reflection and passivation films were coated on both sides, followed by screen printing of Argentum (Ag) and Argentum/Aluminum (Ag/Al) on front and back contacts, respectively. Bifacial solar cells without BSF exhibited open circuit voltage (VOC) of 535 mV for front and 480 mV for back surface. With Al-alloyed BSF bifacial solar cells, the VOC improved to 580 mV for the front surface and 560 mV for the back surface. Simulation of bifacial solar cells using PC1D and AFORS software demonstrated good agreement with experimental results. Simulations showed that best bifacial solar cells are achieved through a combination of high lifetime wafer, low recombination back surface field, reduced contact resistance, and superior surface passivation.

  6. 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...

  7. 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.

  8. General purpose, field-portable cell-based biosensor platform.

    Science.gov (United States)

    Gilchrist, K H; Barker, V N; Fletcher, L E; DeBusschere, B D; Ghanouni, P; Giovangrandi, L; Kovacs, G T

    2001-09-01

    There are several groups of researchers developing cell-based biosensors for chemical and biological warfare agents based on electrophysiologic monitoring of cells. In order to transition such sensors from the laboratory to the field, a general-purpose hardware and software platform is required. This paper describes the design, implementation, and field-testing of such a system, consisting of cell-transport and data acquisition instruments. The cell-transport module is a self-contained, battery-powered instrument that allows various types of cell-based modules to be maintained at a preset temperature and ambient CO(2) level while in transit or in the field. The data acquisition module provides 32 channels of action potential amplification, filtering, and real-time data streaming to a laptop computer. At present, detailed analysis of the data acquired is carried out off-line, but sufficient computing power is available in the data acquisition module to enable the most useful algorithms to eventually be run real-time in the field. Both modules have sufficient internal power to permit realistic field-testing, such as the example presented in this paper. PMID:11544049

  9. 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

  10. Cell membrane potentials induced during exposure to EMP fields

    Energy Technology Data Exchange (ETDEWEB)

    Gailey, P.C.; Easterly, C.E.

    1994-09-01

    Internal current densities and electric fields induced in the human body during exposure to EMP fields are reviewed and used to predict resulting cell membrane potentials. Using several different approaches, membrane potentials of about 100 mV are predicted. These values are comparable to the static membrane potentials maintained by cells as a part of normal physiological function, but the EMP-induced potentials persist for only about 10 ns. Possible biological implications of EMP-induced membrane potentials including conformational changes and electroporation are discussed.

  11. 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

  12. 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...

  13. 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.

  14. Brightness of synchrotron radiation from undulators and bending magnets

    International Nuclear Information System (INIS)

    We consider the maximum of the Wigner distribution (WD) of synchrotron radiation (SR) fields as a possible definition of SR source brightness. Such figure of merit was originally introduced in the SR community by Kim. The brightness defined in this way is always positive and, in the geometrical optics limit, can be interpreted as maximum density of photon flux in phase space. For undulator and bending magnet radiation from a single electron, the WD function can be explicitly calculated. In the case of an electron beam with a finite emittance the brightness is given by the maximum of the convolution of a single electron WD function and the probability distribution of the electrons in phase space. In the particular case when both electron beam size and electron beam divergence dominate over the diffraction size and the diffraction angle, one can use a geometrical optics approach. However, there are intermediate regimes when only the electron beam size or the electron beam divergence dominate. In this asymptotic cases the geometrical optics approach is still applicable, and the brightness definition used here yields back once more the maximum photon flux density in phase space. In these intermediate regimes we find a significant numerical disagreement between exact calculations and the approximation for undulator brightness currently used in literature. We extend the WD formalism to a satisfactory theory for the brightness of a bending magnet. We find that in the intermediate regimes the usually accepted approximation for bending magnet brightness turns out to be inconsistent even parametrically.

  15. Full Field Supercritical Angle Fluorescence Microscopy for live cell imaging

    CERN Document Server

    Barroca, Thomas; Delahaye, Julie; Lévêque-Fort, Sandrine; Fort, Emmanuel

    2013-01-01

    We introduce a full field fluorescence imaging technique with axial confinement of about 100 nm at the sample/substrate interface. Contrary to standard surface imaging techniques, this confinement is obtained through emission filtering. This technique is based on supercritical emission selectivity. It can be implemented on any epifluorescence microscope with a commercial high numerical aperture objective and offers a real time surface imaging capability. This technique is of particular interest for live cell membrane and adhesion studies. Using HEK cells, we show that one can observe simultaneously the surface and in-depth cell phenomena.

  16. Flow field measurements in the cell culture unit

    Science.gov (United States)

    Walker, Stephen; Wilder, Mike; Dimanlig, Arsenio; Jagger, Justin; Searby, Nancy

    2002-01-01

    The cell culture unit (CCU) is being designed to support cell growth for long-duration life science experiments on the International Space Station (ISS). The CCU is a perfused loop system that provides a fluid environment for controlled cell growth experiments within cell specimen chambers (CSCs), and is intended to accommodate diverse cell specimen types. Many of the functional requirements depend on the fluid flow field within the CSC (e.g., feeding and gas management). A design goal of the CCU is to match, within experimental limits, all environmental conditions, other than the effects of gravity on the cells, whether the hardware is in microgravity ( micro g), normal Earth gravity, or up to 2g on the ISS centrifuge. In order to achieve this goal, two steps are being taken. The first step is to characterize the environmental conditions of current 1g cell biology experiments being performed in laboratories using ground-based hardware. The second step is to ensure that the design of the CCU allows the fluid flow conditions found in 1g to be replicated from microgravity up to 2g. The techniques that are being used to take these steps include flow visualization, particle image velocimetry (PIV), and computational fluid dynamics (CFD). Flow visualization using the injection of dye has been used to gain a global perspective of the characteristics of the CSC flow field. To characterize laboratory cell culture conditions, PIV is being used to determine the flow field parameters of cell suspension cultures grown in Erlenmeyer flasks on orbital shakers. These measured parameters will be compared to PIV measurements in the CSCs to ensure that the flow field that cells encounter in CSCs is within the bounds determined for typical laboratory experiments. Using CFD, a detailed simulation is being developed to predict the flow field within the CSC for a wide variety of flow conditions, including microgravity environments. Results from all these measurements and analyses of the

  17. 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.

  18. 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.

  19. 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...

  20. Brightness, coherence, and propagation characteristics of synchrotron radiation

    International Nuclear Information System (INIS)

    A formalism is presented by means of which the propagation and imaging characteristics of synchrotron radiation can be studied, taking into account the effects of diffraction, electron beam emittance, and the transverse and longitudinal extent of the source. An important quantity in this approach is the Wigner distribution of the electric fields, which can be interpreted as a phase-space distribution of photon flux, and thus can be identified with the brightness. When integrated over the angular variables, the brightness becomes the intensity distribution in the spatial variables and when integrated over the spatial variables, it becomes the intensity distribution in angular variables. The brightness so defined transforms through a general optical medium in exactly the same way as in the case of a collection of geometric rays. Finally, the brightness of different electrons adds in a simple way. Optical characteristics of various synchrotron radiation sources - bending magnets, wigglers and undulators, are analyzed using this formalism

  1. 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...

  2. Precise and long-term tracking of adipose-derived stem cells and their regenerative capacity via superb bright and stable organic nanodots.

    Science.gov (United States)

    Ding, Dan; Mao, Duo; Li, Kai; Wang, Xiaomin; Qin, Wei; Liu, Rongrong; Chiam, David Shunzhong; Tomczak, Nikodem; Yang, Zhimou; Tang, Ben Zhong; Kong, Deling; Liu, Bin

    2014-12-23

    Monitoring and understanding long-term fate and regenerative therapy of administrated stem cells in vivo is of great importance. Herein we report organic nanodots with aggregation-induced emission characteristics (AIE dots) for long-term tracking of adipose-derived stem cells (ADSCs) and their regenerative capacity in living mice. The AIE dots possess high fluorescence (with a high quantum yield of 25±1%), excellent biological and photophysical stabilities, low in vivo toxicity, and superb retention in living ADSCs with negligible interference on their pluripotency and secretome. These AIE dots also exhibit superior in vitro cell tracking capability compared to the most popular commercial cell trackers, PKH26 and Qtracker 655. In vivo quantitative studies with bioluminescence and GFP labeling as the controls reveal that the AIE dots can precisely and quantitatively report the fate of ADSCs and their regenerative capacity for 42 days in an ischemic hind limb bearing mouse model. PMID:25427294

  3. 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

  4. 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.

  5. 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

  6. Bright Transients discovered by PSST

    Science.gov (United States)

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

    2016-04-01

    Seven 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).

  7. 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).

  8. Electromechanical effects on multilayered cells in nonuniform rotating fields

    Science.gov (United States)

    Sebastián, José Luis; Muñoz, Sagrario; Sancho, Miguel; Martínez, Genoveva; Álvarez, Gabriel

    2011-07-01

    We use the Maxwell stress tensor to calculate the dielectrophoretic force and electrorotational torque acting on a realistic four-shelled model of the yeast Saccharomyces cerevisiae in a nonuniform rotating electric field generated by four coplanar square electrodes. The comparison of these results with numerical calculations of the dipolar and quadrupolar contributions obtained from an integral equation for the polarization charge density shows the effect of the quadrupole contribution in the proximity of the electrode plane. We also show that under typical experimental conditions the substitution of the multilayered cell by an equivalent cell with homogeneous permittivity underestimates the quadrupole contribution to the force and torque by 1 order of magnitude.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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 ...

  16. Phase cell cluster expansion for Euclidean field theories

    International Nuclear Information System (INIS)

    We adapt the cluster expansion first used to treat infrared problems for lattice models (a mass zero cluster expansion) to the usual field theory situation. The field is expanded in terms of spectral block spin functions and the cluster expansion given in terms of the expansion coefficients (phase cell variables); the other cluster expansion expresses correlation functions in terms of contributions from finite coupled subsets of these variables. Most of the present work is carried through in d space time dimensions (for phi42 the details of the cluster expansion are pursued and convergence is proven). Thus most of the results in this present work will apply to a treatment of phi43 to which we hope to return in a succeeding paper. Of particular interest in this paper is a substitute for the stability of the vaccum bound appropriate to this cluster expansion (for d = 2 and d = 3), and the new method for performing estimates with tree graphs. The phase cell cluster expansions have the renormalization group incorporated intimately into their structure. We hope they will be useful ultimately in treating four dimensional field theories

  17. 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.

  18. Electromagnetic field influences on cell surface potential and cell division in saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    The effect of electromagnetic field on cell surface potential and cell division were studied in s.cerevisiae. The strains used were, GM3 (a/gal 10,trp1, ura4, met 8, ade 5,7,les1, ilvl,arol D, suc-mal, cupr.)and ural (a/urap+w-c 321, R E 221, R) an electromagnetic field (h) .O.I.T, cell resistance (R) increased from 0.158 MΩ to 0.200 M Ω through 5 min. The magnetic field (MF) were switching off. The resistance spontaneously increased reaching 1.000 M Ω at the 9 Th min. However, slowly decrease occurred and reaching 0.560 M Omega at the 15 Th min. By using the MF after 15 min., the resistance value reaching 0.180 M OMEGA, through 15-25 min and cell potential (V) ranged between 130-240 mV. Cell culture, of two strains (same mating type) was used, the resistance, R., was 4000 M Ω and V; 600 mV with two cycles min, R; reached 3200 M Ω. On further cycle of (H) led to a huge sudden decrease of R; 0.176 M Ω the cell numbers were depended, upon the cell potential, due to the application of (H). For the first strain used, cell number decreased from 2x106 cells/ml to 1.5x106 cells/ml and from 2.1x108 cells/ml to 1.7x108 cells/ml after 5 min exposure to (H) for culture incubated at 30 degree on log and stationary phases respectively. While, the cell number in ural was decreased from 3.5x106 cells/ml and from 1.78x108 cells/ ml. to 1.71x108 cells/ml through 5 min exposure to (H) for culture incubated at 30 degree on log and stationary phases respectively

  19. Silicon solar cells with polysilicon emitters and back surface fields

    Science.gov (United States)

    Du, Jiang; Berndt, Lyall P.; Tarr, N. Garry

    2010-06-01

    The first solar cells using in-situ doped polysilicon contacts to form both emitter and back surface field (BSF) regions are reported. The use of polysilicon contacts permits extremely low thermal budget processing (maximum 850°C 5 sec for dopant activation), preserving substrate properties. The effectiveness of the BSF is best seen with backside illumination, where the photocurrent under natural sunlight is found to be over 30% of that obtained with frontside illumination, even though the substrate thickness is comparable to the minority carrier diffusion length. The applicability of the structure to bifacial operation is considered.

  20. 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.

  1. Scintillation camera brightness calibration apparatus

    International Nuclear Information System (INIS)

    Circuitry is described for calibrating the brightness of a cathode ray tube display and recording apparatus comprising: 1) intensity control means for adjusting the intensity of the cathode ray tube beam; 2) light sensitive means disposed to receive light emitted from the cathode ray tube and generating a first electrical signal having a magnitude dependent upon the intensity of the emitted light; 3) reference signal generating means for generating a second electrical signal of predetermined magnitude; and 4) electrical signal comparison means coupled to the light sensitive means and the reference signal generating means for comparing the magnitude of the first and second electrical signals. (author)

  2. 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

  3. 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.

  4. Self-Sealing Wet Chemistry Cell for Field Analysis

    Science.gov (United States)

    Beegle, Luther W.; Soto, Juancarlos; Lasnik, James; Roark, Shane

    2012-01-01

    In most analytical investigations, there is a need to process complex field samples for the unique detection of analytes, especially when detecting low concentration organic molecules that may identify extraterrestrial life. Wet chemistry based instruments are the techniques of choice for most laboratory- based analysis of organic molecules due to several factors including less fragmentation of fragile biomarkers, and ability to concentrate target species resulting in much lower limits of detection. Development of an automated wet chemistry preparation system that can operate autonomously on Earth and is also designed to operate under Martian ambient conditions will demonstrate the technical feasibility of including wet chemistry on future missions. An Automated Sample Processing System (ASPS) has recently been developed that receives fines, extracts organics through solvent extraction, processes the extract by removing non-organic soluble species, and delivers sample to multiple instruments for analysis (including for non-organic soluble species). The key to this system is a sample cell that can autonomously function under field conditions. As a result, a self-sealing sample cell was developed that can autonomously hermetically seal fines and powder into a container, regardless of orientation of the apparatus. The cap is designed with a beveled edge, which allows the cap to be self-righted as the capping motor engages. Each cap consists of a C-clip lock ring below a crucible O-ring that is placed into a groove cut into the sample cap.

  5. High brightness angled cavity quantum cascade lasers

    International Nuclear Information System (INIS)

    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−2 sr−1 is obtained, which marks the brightest QCL to date

  6. 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.

  7. Fuel cell progress and its application in field of transportation in China

    International Nuclear Information System (INIS)

    'Full text:' The paper presents the latest fuel cell technology progress in China and its application in field of transportation. The units who are engaged in fuel cell technology and fuel cell products will be introduced and their applications in light fuel cell vehicles and fuel cell cars as well as fuel cell buses will be included. (author)

  8. Ion Transport within High Electric Fields in Nanogap Electrochemical Cells.

    Science.gov (United States)

    Xiong, Jiewen; Chen, Qianjin; Edwards, Martin A; White, Henry S

    2015-08-25

    Ion transport near an electrically charged electrolyte/electrode interface is a fundamental electrochemical phenomenon that is important in many electrochemical energy systems. We investigated this phenomenon using lithographically fabricated thin-layer electrochemical cells comprising two Pt planar electrodes separated by an electrolyte of nanometer thickness (50-200 nm). By exploiting redox cycling amplification, we observed the influence of the electric double layer on transport of a charged redox couple within the confined electrolyte. Nonclassical steady-state peak shaped voltammograms for redox cycling of the ferrocenylmethyltrimethylammonium redox couple (FcTMA(+/2+)) at low concentrations of supporting electrolyte (≤10 mM) results from electrostatic interactions between the redox ions and the charged Pt electrodes. This behavior contrasts to sigmoidal voltammograms with a diffusion-limited plateau observed in the same electrochemical cells in the presence of sufficient electrolyte to screen the electrode surface charge (200 mM). Moreover, steady-state redox cycling was depressed significantly within the confined electrolyte as the supporting electrolyte concentration was decreased or as the cell thickness was reduced. The experimental results are in excellent agreement with predictions from finite-element simulations coupling the governing equations for ion transport, electric fields, and the redox reactions. Double layer effects on ion transport are generally anticipated in highly confined electrolyte and may have implications for ion transport in thin layer and nanoporous energy storage materials. PMID:26190513

  9. 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.

  10. Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

    Science.gov (United States)

    Marcos-Campos, I.; Asín, L.; Torres, T. E.; Marquina, C.; Tres, A.; Ibarra, M. R.; Goya, G. F.

    2011-05-01

    In this work, the capability of primary, monocyte-derived dendritic cells (DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a strategy to induce selective cell death in these MNP-loaded DCs using external alternating magnetic fields (AMFs) is reported. No significant decrease in the cell viability of MNP-loaded DCs, compared to the control samples, was observed after five days of culture. The number of MNPs incorporated into the cytoplasm was measured by magnetometry, which confirmed that 1-5 pg of the particles were uploaded per cell. The intracellular distribution of these MNPs, assessed by transmission electron microscopy, was found to be primarily inside the endosomic structures. These cells were then subjected to an AMF for 30 min and the viability of the blank DCs (i.e. without MNPs), which were used as control samples, remained essentially unaffected. However, a remarkable decrease of viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was observed after the same 30 min exposure to an AMF. The same results were obtained using MNPs having either positive (NH2 + ) or negative (COOH - ) surface functional groups. In spite of the massive cell death induced by application of AMF to MNP-loaded DCs, the number of incorporated magnetic particles did not raise the temperature of the cell culture. Clear morphological changes at the cell structure after magnetic field application were observed using scanning electron microscopy. Therefore, local damage produced by the MNPs could be the main mechanism for the selective cell death of MNP-loaded DCs under an AMF. Based on the ability of these cells to evade the reticuloendothelial system, these complexes combined with an AMF should be considered as a potentially powerful tool for tumour therapy.

  11. Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

    International Nuclear Information System (INIS)

    In this work, the capability of primary, monocyte-derived dendritic cells (DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a strategy to induce selective cell death in these MNP-loaded DCs using external alternating magnetic fields (AMFs) is reported. No significant decrease in the cell viability of MNP-loaded DCs, compared to the control samples, was observed after five days of culture. The number of MNPs incorporated into the cytoplasm was measured by magnetometry, which confirmed that 1-5 pg of the particles were uploaded per cell. The intracellular distribution of these MNPs, assessed by transmission electron microscopy, was found to be primarily inside the endosomic structures. These cells were then subjected to an AMF for 30 min and the viability of the blank DCs (i.e. without MNPs), which were used as control samples, remained essentially unaffected. However, a remarkable decrease of viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was observed after the same 30 min exposure to an AMF. The same results were obtained using MNPs having either positive (NH2+) or negative (COOH-) surface functional groups. In spite of the massive cell death induced by application of AMF to MNP-loaded DCs, the number of incorporated magnetic particles did not raise the temperature of the cell culture. Clear morphological changes at the cell structure after magnetic field application were observed using scanning electron microscopy. Therefore, local damage produced by the MNPs could be the main mechanism for the selective cell death of MNP-loaded DCs under an AMF. Based on the ability of these cells to evade the reticuloendothelial system, these complexes combined with an AMF should be considered as a potentially powerful tool for tumour therapy.

  12. Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

    Energy Technology Data Exchange (ETDEWEB)

    Marcos-Campos, I; AsIn, L; Torres, T E; Tres, A; Ibarra, M R; Goya, G F [Instituto de Nanociencia de Aragon (INA), Mariano Esquillor s/n, CP 50018, Zaragoza (Spain); Marquina, C, E-mail: goya@unizar.es [Condensed Matter Department, Sciences Faculty, University of Zaragoza, 50009 (Spain)

    2011-05-20

    In this work, the capability of primary, monocyte-derived dendritic cells (DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a strategy to induce selective cell death in these MNP-loaded DCs using external alternating magnetic fields (AMFs) is reported. No significant decrease in the cell viability of MNP-loaded DCs, compared to the control samples, was observed after five days of culture. The number of MNPs incorporated into the cytoplasm was measured by magnetometry, which confirmed that 1-5 pg of the particles were uploaded per cell. The intracellular distribution of these MNPs, assessed by transmission electron microscopy, was found to be primarily inside the endosomic structures. These cells were then subjected to an AMF for 30 min and the viability of the blank DCs (i.e. without MNPs), which were used as control samples, remained essentially unaffected. However, a remarkable decrease of viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was observed after the same 30 min exposure to an AMF. The same results were obtained using MNPs having either positive (NH{sub 2}{sup +}) or negative (COOH{sup -}) surface functional groups. In spite of the massive cell death induced by application of AMF to MNP-loaded DCs, the number of incorporated magnetic particles did not raise the temperature of the cell culture. Clear morphological changes at the cell structure after magnetic field application were observed using scanning electron microscopy. Therefore, local damage produced by the MNPs could be the main mechanism for the selective cell death of MNP-loaded DCs under an AMF. Based on the ability of these cells to evade the reticuloendothelial system, these complexes combined with an AMF should be considered as a potentially powerful tool for tumour therapy.

  13. The Physics and Applications of High Brightness Beams: Working Group A Summary on High Brightness Beam Production

    International Nuclear Information System (INIS)

    Working group A was devoted to high brightness beam production and characterization. The presentations and discussions could be categorized as cathode physics, new photoinjector designs, computational modeling of high brightness beams, and new experimental methods and results. Several novel injector and cathode designs were presented. However, a standard 1.5 cell rf photoinjector is still the most common source for high brightness beams. New experimental results and techniques were presented and thoroughly discussed. The brightest beam produced in a rf photoinjector published at the time of the workshop is approximately 2 1014 A/(m-rad)2 at Sumitomo Heavy Industries in Japan with 1 nC of charge, a 9 ps FWHM long laser pulse and a normalized transverse emittance of 1.2 pm. The emittance was achieved by utilizing a temporally flat laser pulse which decreased the emittance by an estimated factor of 2 from the beam produced with a Gaussian pulse shape with an identical pulse length

  14. VERITAS Observations under Bright Moonlight

    CERN Document Server

    ,

    2015-01-01

    The presence of moonlight is usually a limiting factor for imaging atmospheric Cherenkov telescopes due to the high sensitivity of the camera photomultiplier tubes (PMTs). In their standard configuration, the extra noise limits the sensitivity of the experiment to gamma-ray signals and the higher PMT currents also accelerates PMT aging. Since fall 2012, observations have been carried out with VERITAS under bright moonlight (Moon illumination $> 35\\%$), in two observing modes, by reducing the voltage applied to the PMTs and with UV bandpass filters, which allow observations up to $\\sim80\\%$ Moon illumination resulting in $29\\%$ more observing time over the course of the year. In this presentation, we provide details of these new observing modes and their performance relative to the standard VERITAS observations.

  15. [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

  16. Enhancing the brightness of high current electron guns

    International Nuclear Information System (INIS)

    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

  17. The lowest surface brightness disc galaxy known

    International Nuclear Information System (INIS)

    The discovery of a galaxy with a prominent bulge and a dominant extremely low surface brightness disc component is reported. The profile of this galaxy is very similar to the recently discovered giant low surface brightness galaxy Malin 1. The disc central surface brightness is found to be ∼ 26.4 Rμ, some 1.5 mag fainter than Malin 1 and thus by far the lowest yet observed. (author)

  18. The surface brightness of 1550 galaxies in Fornax: automated galaxy surface photometry: Pt. 2

    International Nuclear Information System (INIS)

    A survey of a complete sample of galaxies in the region of the Fornax cluster is presented. Measurements with the Automatic Plate Measuring machine are used to derive the observed distribution of galaxy surface brightness for 1550 objects. Corrections for surface brightness dependent selection effects are then made in order to estimate the true distribution. It is found that the sample (with 16.6 ≤ Msub(APM) ≤ 19.1) is divided into two distinct populations. The 'normal' galaxies with extrapolated central surface brightness Ssub(x) ≤ 22.5 Bμ form a uniformly distributed background of field galaxies. Low surface brightness galaxies (Ssub(x) ≥ 22.5 Bμ), on the other hand, are strongly clumped about the cluster centre. There appear to be few low surface brightness field galaxies. (author)

  19. 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.

  20. 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

  1. Cell growth, intracellular calcium concentration and metabolic cooperation measured in cells exposed to 50 Hz electromagnetic fields

    International Nuclear Information System (INIS)

    Colony-forming efficiency, DNA/protein and DNA/cell were measured in cells exposed to magnetic fields of 0.2 and 1 mT at a frequency of 50 Hz. Intracellular calcium concentrations were measured in cells exposed to 0.3 and 1 mT at 50 Hz. Metabolic cooperation was measured in cells exposed to 1 mT at 50 Hz. No significant effects of the fields were observed. 20 refs., 10 figs

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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)

  8. 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.

  9. Soliton Fay identities. II. Bright soliton case

    OpenAIRE

    Vekslerchik, V. E.

    2015-01-01

    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.

  10. 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.

  11. Galaxy selection and the surface brightness distribution

    CERN Document Server

    McGaugh, S S; Schombert, J M

    1995-01-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney (1976) suggested that the constancy of disk central surface brightness noticed by Freeman (1970) was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (\\ie approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity ...

  12. 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.

  13. 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.

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

    OpenAIRE

    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. Technological advances, like high resolution microscopy together with the possibility to address different membrane components via specific labeling now allows researchers to investigate cell membra...

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

    Science.gov (United States)

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

    2016-02-01

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

  16. 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

  17. 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.

  18. 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.

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

    OpenAIRE

    Tahereh Pourmirjafari Firoozabadi; Zeinab Shankayi; Azam Izadi; Seyed Mohammad Pourmirjafari Firoozabadi

    2015-01-01

    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...

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

    Science.gov (United States)

    Pourmirjafari Firoozabadi, Tahereh; Shankayi, Zeinab; Izadi, Azam; Pourmirjafari Firoozabadi, Seyed Mohammad

    2015-01-01

    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. PMID:25685747

  1. 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.

  2. 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

  3. 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.

  4. Tuning nano electric field to affect restrictive membrane area on localized single cell nano-electroporation

    Science.gov (United States)

    Santra, Tuhin Subhra; Wang, Pen-Cheng; Chang, Hwan-You; Tseng, Fan-Gang

    2013-12-01

    Interaction of electric field with biological cells is an important phenomenon for field induced drug delivery system. We demonstrate a selective and localized single cell nano-electroporation (LSCNEP) by applying an intense electric field on a submicron region of the single cell membrane, which can effectively allow high efficient molecular delivery but low cell damage. The delivery rate is controlled by adjusting transmembrane potential and manipulating membrane status. Thermal and ionic influences are deteriorated from the cell membrane by dielectric passivation. Either reversible or irreversible by LSCNEP can fully controlled with potential applications in medical diagnostics and biological studies.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

  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. 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

  13. Performance of the high brightness linac for the Advanced Free Electron Laser Initiative at Los Alamos

    Science.gov (United States)

    Sheffield, R. L.; Austin, R. H.; Chan, K. D. C.; Gierman, S. M.; Kinross-Wright, J. M.; Kong, S. H.; Nguyen, D. C.; Russell, S. J.; Timmer, C. A.

    1993-08-01

    The AFEL accelerator has produced beams of greater than 2 x 10(exp 12) A/m(exp 2) at 1 nC (brightness = 2*I/(var epsilon)(exp 2), with I greater than 100 A and (var epsilon) of than 2(pi) mm-mrad normalized ms emittance). The 1300 MHz standing-wave accelerator uses on-axis coupling cells. The electron source is a photoinjector with a CsK2Sb photocathode. The photoinjector is an integral part of a single 11-cell accelerator structure. The accelerator operates between 12 and 18 MeV. The beam emittance growth in the accelerator is minimized by using a photoinjector, a focusing solenoid to correct the emittance growth due to space charge, and a special design of the coupling slots between accelerator cavities to minimize quadrupole effects. This paper describes the experimental results and compares those results with PARMELA simulation. The simulation code PARMELA was modified for this effort. This modified version uses SUPERFISH files for the accelerator cavity fields, MAFIA files for the fields due to the coupling slots in the accelerator cells, and POISSON files for the solenoid field in the gun region.

  14. 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.

  15. 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.

  16. Surface Brightness Profiles of Seyfert Galaxies

    CERN Document Server

    Tugay, A V

    2014-01-01

    We built r-band surface brightness profiles by SDSS data for 16 Seyfert galaxies observed in Crimean Astrophysical Observatory. Obtained profiles can be used for finding more accurate lightcurves for these galaxies.

  17. 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...

  18. 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...

  19. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    The intrinsic surface brightness Ssub(e) of 500 disc galaxies (0<=T<=9) drawn from the Second Reference Catalogue is computed and it is shown that Ssub(e) does not correlate significantly with Msub(B), (B-V) or type. This is consistent with the notion that there is a heavy selection bias in favour of disc galaxies with that particular surface brightness which allows inclusion in the catalogue over the largest volume of space. (author)

  20. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    It is proposed that Freeman's discovery that the extrapolated central surface brightness of spiral galaxies is approximately constant can be simply explained if the galaxies contain a spheroidal component which dominates the light in their outer isophotes. Calculations of an effective central surface brightness indicate a wide spread of values. This requires either a wide spread in disc properties or significant spheroidal components or, most probably, both. (author)

  1. 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

  2. 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.

  3. Wave and Wind Direction Effects on SFMR Brightness Temperatures

    Science.gov (United States)

    Holbach, Heather; Uhlhorn, Eric; Bourassa, Mark

    2015-04-01

    Surface winds in a tropical cyclone are essential for determining its strength. Currently the Stepped-Frequency Microwave Radiometer (SFMR) and Global Positioning System (GPS) dropwindsondes are the main instruments used for obtaining in situ surface wind measurements. The platforms for these instruments are the National Oceanographic and Atmospheric Administration (NOAA) P-3 and Air Force C-130J hurricane hunter aircraft. The SFMR measures sea surface microwave brightness temperatures at six frequencies ranging from 4.7 to 7.2 GHz. Surface wind speed estimates are obtained from these brightness temperatures by using a retrieval algorithm that employs a geophysical model function relating surface emissivity and wind speed. The SFMR is designed to obtain a single nadir track of surface wind speeds directly beneath the aircraft during level flight and not when turning because of the complexity of the wave field and foam distribution when the SFMR views the surface off-nadir or during aircraft rolls. However, the effects of the wave field on the measurements can be investigated using measurements obtained during the 2008 and 2014 Atlantic hurricane seasons. An SFMR module was flown in precipitation-free regions of the tropical cyclones to collect data at specified roll angles of 15°, 30°, 45°, and 60° in some cases. Excess brightness temperatures are then calculated with respect to zero wind speed values and independent of wind direction. An asymmetry is found in the resulting excess brightness temperatures. It is hypothesized that this asymmetry is caused by the direction of wave propagation and the angle at which the wave field is viewed by the SFMR. Wind direction may also play a role in the asymmetry. To analyze the asymmetry further measurement from WindSat will be used. Once the relationship is determined between surface wind speed, brightness temperature, and incidence angle a technique will be developed to obtain a surface wind speed when the aircraft is

  4. 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...

  5. 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 ...

  6. 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...

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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...

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

    OpenAIRE

    2014-01-01

    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 ra...

  16. 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. ...

  17. Adapting High Brightness Relativistic Electron Beams for Ultrafast Science

    Science.gov (United States)

    Scoby, Cheyne Matthew

    This thesis explores the use of ultrashort bunches generated by a radiofrequency electron photoinjector driven by a femtosecond laser. Rf photoinjector technology has been developed to generate ultra high brightness beams for advanced accelerators and to drive advanced light source applications. The extremely good quality of the beams generated by this source has played a key role in the development of 4th generation light sources such as the Linac Coherent Light Source, thus opening the way to studies of materials science and biological systems with high temporal and spatial resolution. At the Pegasus Photoinjector Lab, we have developed the application of a BNL/SLAC/UCLA 1.6-cell rf photoinjector as a tool for ultrafast science in its own right. It is the aim of this work to explore the generation of ultrashort electron bunches, give descriptions of the novel ultrafast diagnostics developed to be able to characterize the electron bunch and synchronize it with a pump laser, and share some of the scientific results that were obtained with this technology at the UCLA Pegasus laboratory. This dissertation explains the requirements of the drive laser source and describes the principles of rf photoinjector design and operation necessary to produce electron bunches with an rms longitudinal length < 100 femtoseconds containing 107 - 108 electrons per bunch. In this condition, when the laser intensity is sufficiently high, multiphoton photoemission is demonstrated to be more efficient in terms of charge yield than single photon photoemission. When a short laser pulse hits the cathode the resulting beam dynamics are dominated by a strong space charge driven longitudinal expansion which leads to the creation of a nearly ideal uniformly filled ellipsoidal distribution. These beam distributions are characterized by linear space charge forces and hence by high peak brightness and small transverse emittances. This regime of operation of the RF photoinjector is also termed the

  18. Numerical Modeling of Electromagnetic Field in the Biological Cell

    Czech Academy of Sciences Publication Activity Database

    Vlachová-Hutová, E.; Kříž, P.; Gescheidtová, E.; Bartušek, Karel

    Cambridge: The Electromagnetics Academy, 2014, s. 1890-1894. ISBN 978-1-934142-28-8. [PIERS 2014. Progress In Electromagnetics Research Symposium /35./. Guangzhou (CN), 25.08.2014-28.08.2014] R&D Projects: GA ČR GAP102/12/1104 Institutional support: RVO:68081731 Keywords : electromagnetic field * iological ell * numerical modeling Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  19. Field tests and examinations in cell of French fuel assemblies

    International Nuclear Information System (INIS)

    This paper presents the field tests carried out on more than 70 assemblies and those realized at the hot laboratory on a whole assembly of 25 rods taken from pressurized water power plants operating in France: dimension examination; fission gas release; oxidation and hydridation of cans

  20. Physics design of the high brightness linac for the advanced free-electron laser initiative at Los Alamos

    Science.gov (United States)

    Sheffield, R. L.; Browman, M. J.; Carlsten, B. E.; Young, L. M.

    1992-07-01

    Free-electron lasers and high energy physics accelerators have increased the demand for very high brightness electron-beam sources. This paper describes the design of an accelerator that can produce beams of greater than 7×1011A/m2 (brightness equal to 21/ɛ2, with ɛ = 90% normalized emittance, equivalent to four times the rms emittance). The beam emittance growth in the accelerator is minimized by: producing a short electron bunch in a high gradient rf cavity, using a focusing solenoid to correct the emittance growth caused by space charge, and designing the coupling slots between accelerator cavities to minimize quadrupole effects. The simulation code PARMELA was modified for this design effort. This modified version uses SUPERFISH output files for the accelerator cavity fields, MAFIA output files for the 3-D perturbation fields caused by the coupling slots in the accelerator cells, and POISSON output files for the solenoid field in the gun region. The results from simulations are, at 2.3 nC, a peak current of 180 A and a 90% emittance of 6.4π mm mrad, and, at 4 nC a peak current of 300 A and a 90% emittance of 9.4π mrad. The exit energy from the linac is 20 MeV for both cases. A magnetic pulse compressor can be used to further increase the peak current.

  1. Cancer cell imaging by stable wet near-field scanning optical microscope with resonance tracking method

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyoung-Duck [Sungkyunkwan University, Suwon (Korea, Republic of); Inha University, Incheon (Korea, Republic of); Park, Doo-Jae; Jeong, Mun-Seok [Sungkyunkwan University, Suwon (Korea, Republic of); Choi, Geun-Chang [Seoul National University, Seoul (Korea, Republic of); Lee, Seung-Gol [Inha University, Incheon (Korea, Republic of); Byeon, Clare-Chisu [Kyungpook National University, Daegu (Korea, Republic of); Choi, Soo-Bong [Incheon National University, Incheon (Korea, Republic of)

    2014-05-15

    We report on a successful topographical and optical imaging of various cancer cells in liquid and in air by using a stable wet near-field scanning optical microscope that utilizes a resonance tracking method. We observed a clear dehydration which gives rise to a decrease in the cell volume down to 51%. In addition, a micro-ball lens effect due to the round-shaped young cancer cells was observed from near-field imaging, where the refractive index of young cancer cells was deduced.

  2. Cancer cell imaging by stable wet near-field scanning optical microscope with resonance tracking method

    International Nuclear Information System (INIS)

    We report on a successful topographical and optical imaging of various cancer cells in liquid and in air by using a stable wet near-field scanning optical microscope that utilizes a resonance tracking method. We observed a clear dehydration which gives rise to a decrease in the cell volume down to 51%. In addition, a micro-ball lens effect due to the round-shaped young cancer cells was observed from near-field imaging, where the refractive index of young cancer cells was deduced.

  3. 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.

  4. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.; Houlihan, John; Mullane, Mark; O'Neill, Eamonn

    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....... Large apertures result in high order transverse modes, filamentation and spatio-temporal instabilities, all of which degrade spatial coherence and therefore brightness. We shall describe a combined assault on three fronts: (1) minimise aperture size required for a given power by maximising the facet...... damage threshold, (2) for a given aperture, minimise self-focusing and filamentation by minimising the effective nonlinear coefficient (the alpha parameter), and (3) for a given aperture and nonlinear coefficient, develop optical cavities and propagation structures to suppress filamentation and high...

  5. 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....... Large apertures result in high order transverse modes, filamentation and spatio-temporal instabilities, all of which degrade spatial coherence and therefore brightness. We shall describe a combined assault on three fronts: (1) minimise aperture size required for a given power by maximising the facet...... damage threshold, (2) for a given aperture, minimise self-focusing and filamentation by minimising the effective nonlinear coefficient (the alpha parameter), and (3) for a given aperture and nonlinear coefficient, develop optical cavities and propagation structures to suppress filamentation and high...

  6. Potassium ion influx measurements on cultured Chinese hamster cells exposed to 60-hertz electromagnetic fields

    International Nuclear Information System (INIS)

    Potassium ion influx was measured by monitoring 42KCl uptake by Chinese hamster ovary (CHO) cells grown in suspension culture and exposed in the culture medium to 60-Hz electromagnetic fields up to 2.85 V/m. In the presence of the field CHO cells exhibited two components of uptake, the same as previously observed for those grown under normal conditions; both these components of influx were decreased when compared to sham-exposed cells. Although decreases were consistently observed in exposed cells when plotted as loge of uptake, the differences between the means of the calculated fluxes of exposed and sham-exposed cells were quite small (on the order of 4-7%). When standard deviations were calculated, there was no significant difference between these means; however, when time-paired uptake data were analyzed, the differences were found to be statistically significant. Cells exposed only to the magnetic field exhibited similar small decreases in influx rates when compared to sham-exposed cells, suggesting that the reduction in K+ uptake could be attributed to the magnetic field. Additionally, intracellular K+ levels were measured over a prolonged exposure period (96 h), and no apparent differences in intracellular K+ levels were observed between field-exposed and sham-exposed cultures. These results indicate that high-strength electric fields have a small effect on the rate of transport of potassium ions but no effect on long-term maintenance of intracellular K+

  7. Immunohistochemical staining of human sperm cells in smears from sexual assault cases

    DEFF Research Database (Denmark)

    Christoffersen, S.

    2011-01-01

    significantly decreases the time used to screen smears. By further using an EnVision+ (DAKO) protocol, it was possible to create an immunohistochemical staining method to visualize sperm cells in bright-field microscopy with the same level of certainty as when using SPERM HY-LITER (TM)....... sperm cells. In this work the goal was to develop a procedure to rapidly visualize human sperm cells in smear slides with the use of bright-field microscopy. Using SPERM HY-LITER (TM) by Independent Forensics, human sperm cells are visualized using a fluorescently labeled mouse antibody which...

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. Discovery program for bright quasars: preliminary results

    International Nuclear Information System (INIS)

    A program has been undertaken to obtain a complete sample of bright quasars on the basis of ultraviolet color excess. Spectroscopic examination of candidates selected from two-color Schmidt telescope films has yielded four new quasars brighter than B = 16/sup m/5, with the candidate list containing two more previously identified. Magnitudes, color indices, and redshifts are presented for the new discoveries, along with positions and finding charts. Although the sample is not yet complete, these first results suggest that bright quasars have a low surface density

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

    International Nuclear Information System (INIS)

    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. The 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 because of its ability to resist the 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 effective single-mode operation. (paper)

  16. 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

  17. 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

  18. 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.

  19. Development of pierce type high-brightness electron gun

    International Nuclear Information System (INIS)

    A Pierce type electron gun has been developed. High voltage of 200kV DC is effective for the purpose of high brightness. A compact insulation gas tank of 600mmx600mmφ, and a very simple structure of high voltage feeding is realized by insulation designing using an electric field analysis. At the test bench experiments, high voltage of 200kV was achieved, which justifies our design. After a measurement of electron beam characteristics, the gun has been installed into linac system and operated stably. (author)

  20. 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.

  1. 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.

  2. 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)

  3. A new magnetic white dwarf discovered during the Large Bright Quasar Survey

    International Nuclear Information System (INIS)

    A previously unknown magnetic white dwarf has been discovered as part of the Large, Bright Quasar Survey (Foltz et al., 1988). The absorption features are identified with transitions of hydrogen and are analyzed in the context of high-field Zeeman models to derive a polar dipole field strength of 24 x 10 to the 6th G at the stellar surface. 11 refs

  4. Cell death induced by application of time-varying magnetic fields on nanoparticle-loaded dendritic cells

    CERN Document Server

    Marcos-Campos, I; Torres, T E; Marquina, C; Tres, A; Ibarra, M R; Goya, G F

    2010-01-01

    Aim: To assess the capability of monocyte-derived dendritic cells (DCs) to take Fe3O4 magnetic nanoparticles (MNPs), keeping their viability. To provoke cell death on these MNPs-loaded DCs using an external alternating magnetic field (AMF). Material & methods: Peripheral blood mononuclear cells were isolated from normal blood and platelets removed by centrifugation. Immunoselected CD14+ cells were cultured for 5 days, and the resulting cell phenotype was determined against several markers using flow cytometry. Co-cultures of DCs and MNPs were done overnight. The amount of Fe3O4 nanoparticles incorporated by DCs was quantified by magnetization measurements. MNPs-loaded DCs were exposed to AMF for 30 min and then cell viability was measured using trypan blue and FACS (annexin-propidium iodide) protocols. Morphological changes were investigated using scanning electron microscopy. Results: No significant decrease in cell viability of MNP/loaded DCs was observed up to five days, as compared against control sam...

  5. FACTORS AFFECTING DIELECTROPHORETIC SEPARATION OF CELLS USING HIGH-GRADIENT ELECTRIC FIELD STRENGTH SYSTEM

    Directory of Open Access Journals (Sweden)

    Z. ZAINAL ABIDIN

    2008-04-01

    Full Text Available An investigation on dielectrophoretic separation of cells has been conducted using high-gradient electric field system (HGES. The HGES system consisted of two concentric cylindrical electrodes whereby the space between them was filled with glass beads. The glass beads were found to distort the electric field generated between the two electrodes and thus creating a high field gradient sites that produce dielectrophoretic force for cells collection. In order to study the effectiveness of the system in separating the cells, a series of experiments have been conducted. Here, yeast cells were introduced into the system and the number of cells collected was measured. The effects of voltage, flow rate, type of matrix, height of matrix and sample concentration have been investigated. In addition, the electric field analysis for the HGES has also been carried out using FEMLAB. Results show that the cells collection is influenced by the effect at the condition with and without electric field. Further analysis on the investigating factors enabled one to predict optimum values for voltage, flow rate, type of matrix, and height of matrix and sample concentration in order to improve the efficiency of the system by reducing the effect when no field is applied.

  6. Lattice Development for Pep-X High Brightness Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Nosochkov, Yuri; /SLAC; Cai, Yunhai; /SLAC; Wang, Min-Huey; /SLAC

    2010-08-25

    Design of PEP-X high brightness light source machine is under development at SLAC. The PEP-X is a proposed replacement for the PEP-II in the existing 2.2 km tunnel. Two of the PEP-X six arcs contain DBA type lattice providing 30 dispersion free straights suitable for 3.5 m long undulators. The lattice contains TME cells in the other four arcs and 89.3 m wiggler in a long straight section yielding a horizontal emittance of {approx}0.1 nm-rad at 4.5 GeV. The recent lattice modifications are aimed at increasing the predicted brightness and improving beam dynamic properties. The standard DBA cells are modified into supercells for providing low-{beta} undulator straights. The DBA and TME cell phase advance is better optimized. Harmonic sextupoles are added to minimize the sextupole driven resonance effects and amplitude dependent tune shift. Finally, the injection scheme is changed from vertical to horizontal plane in order to avoid large vertical amplitudes of injected beam within small vertical aperture of undulators.

  7. 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.

  8. 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...

  9. 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

  10. Brightness versus roughness: a multiscale approach

    International Nuclear Information System (INIS)

    A link between roughness and brightness is sought for brass specimens that were superfinished, sandblasted and brushed. Only the blasting conditions are varied in order to get different roughness and brightness. First, a relation between roughness and brightness is sought for specimens that were superfinished and sandblasted. The best relation is obtained using the mean height of the motifs, calculated using a low-pass filter and cut-off length equal to 30 μm, with a logarithmic–logarithmic model. Then, the same type of relation is determined after superfinishing sandblasting and brushing. The core material volume Vmc, computed using a high-pass filter with a cut-off length of 60 μm and a linear–logarithmic relationship, gives the best results. A relation between roughness and brightness that is common to both the pre-brushing state and post-brushing state is identified: the best roughness parameter is the arithmetic mean deviation Sa using a high-pass filter with a cut-off of 15 μm, with a logarithmic–logarithmic relationship. Finally, it is shown that the use of these filtering conditions enables us to verify the model of Beckmann and Spizzichino for the examined specimens. This scale corresponds to the end of the fractal regime and is close to the end of the signal correlation. (paper)

  11. Discussion of high brightness rf linear accelerators

    International Nuclear Information System (INIS)

    The fundamental aspects of high-brightness rf linacs are outlined, showing the breadth and complexity of the technology and indicating that synergism with advancements in other areas is important. Areas of technology reviewed include ion sources, injectors, rf accelerator structures, beam dynamics, rf power, and automatic control

  12. Disassembly of actin structures by nanosecond pulsed electric field is a downstream effect of cell swelling

    OpenAIRE

    Pakhomov, Andrei G.; Xiao, Shu; Pakhomova, Olga N.; Semenov, Iurii; Kuipers, Marjorie A.; Ibey, Bennett L.

    2014-01-01

    Disruption of the actin cytoskeleton structures was reported as one of the characteristic effects of nanosecond-duration pulsed electric field (nsPEF) in both mammalian and plant cells. We utilized CHO cells that expressed the monomeric fluorescent protein (mApple) tagged to actin to test if nsPEF modifies the cell actin directly or as a consequence of cell membrane permeabilization. A train of four 600-ns pulses at 19.2 kV/cm (2 Hz) caused immediate cell membrane poration manifested by YO-PR...

  13. Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells

    Czech Academy of Sciences Publication Activity Database

    Havrdová, M.; Poláková, K.; Skopalík, J.; Vůjtek, M.; Mokdad, A.; Homolková, M.; Tuček, J.; Nebesářová, Jana; Zbořil, R.

    2014-01-01

    Roč. 67, DEC 2014 (2014), s. 149-154. ISSN 0968-4328 Institutional support: RVO:60077344 Keywords : Field emission scanning electronmicroscopy (FE-SEM) * Stem cells * Iron oxide nanoparticles * Cellular morphology * Endosomes * Cell uptake Subject RIV: FD - Oncology ; Hematology Impact factor: 1.988, year: 2014

  14. 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

  15. ORIENTATION REQUIREMENT TO DETECT MAGNETIC FIELD-INDUCTED ALTERATION OF GAP JUNCTION COMMUNICATION IN EPITHELIAL CELLS

    Science.gov (United States)

    ORIENTATION REQUIREMENT TO DETECT MAGNETIC FIELD-INDUCED ALTERATION OF GAP JUNCTION COMMUNICATION IN EPITHELIAL CELLS. OBJECTIVE: We have shown that functional gap junction communication as measured by Lucifer yellow dye transfer (DT) in Clone-9 rat liver epithelial cells, c...

  16. 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.

  17. Electric field-directed cell shape changes, displacement, and cytoskeletal reorganization are calcium dependent

    OpenAIRE

    1988-01-01

    C3H/10T1/2 mouse embryo fibroblasts were stimulated by a steady electric field ranging up to 10 V/cm. Some cells elongated and aligned perpendicular to the field direction. A preferential positional shift toward the cathode was observed which was inhibited by the calcium channel blocker D-600 and the calmodulin antagonist trifluoperazine. Rhodaminephalloidin labeling of actin filaments revealed a field- induced disorganization of the stress fiber pattern, which was reduced when stimulation wa...

  18. Orientation of Red Blood Cells and Rouleaux Disaggregation in Interference Laser Fields

    OpenAIRE

    Kruchenok, J. V.; Bushuk, S. B.; Kurilo, G. I.; Nemkovich, N. A.; Rubinov, A. N.

    2005-01-01

    The effect of interference laser fields on red blood cells (RBCs) was investigated both theoretically and experimentally. The optical trapping and orientation of individual RBC in interference fringes were observed. It was found that RBC rouleaux undergo disaggregation under the action of interference laser fields. To describe the effect of RBC orientation in interference fringes, we used the equation for torque exerted on a discoid dielectric particle in a gradient light field. The experimen...

  19. 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

  20. 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...

  1. Conservation of an ion beam brightness. Study of a non brightness disturbing lens

    International Nuclear Information System (INIS)

    Experimental studies of ion sources prove that large initial brightnesses can be obtained by using the plasma expansion principle. However these brightnesses are usually spoiled by the beam focusing and accelerating systems. A high intensity focusing set up is first theoretically studied, then numerically determined by use of a 7094 IBM computer. Aberrations have been minimized. It has then been possible to construct a set up conserving the source initial brightness. For a 100 mA beam the focusing voltage is 150 kV, the beam study has been done for 350 keV beam final energy. Given is a discussion of results. (author)

  2. 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

  3. 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]-...

  4. 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...

  5. Integrated Field Testing of Fuel Cells and Micro-Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Jerome R. Temchin; Stephen J. Steffel

    2005-11-01

    A technical and economic evaluation of the prospects for the deployment of distributed generation on Long Beach Island, New Jersey concluded that properly sited DG would defer upgrading of the electric power grid for 10 years. This included the deployment of fuel cells or microturbines as well as reciprocating engines. The implementation phase of this project focused on the installation of a 120 kW CHP microturbine system at the Harvey Cedars Bible Conference in Harvey Cedars, NJ. A 1.1 MW generator powered by a gas-fired reciprocating engine for additional grid support was also installed at a local substation. This report contains installation and operation issues as well as the utility perspective on DG deployment.

  6. 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.

  7. 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.

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

    International Nuclear Information System (INIS)

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

  9. 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.

  10. Measurement of the efficiency of cell membrane electroporation using pulsed ac fields

    International Nuclear Information System (INIS)

    Electroporation is a long-established technique used to deliver molecules to cells. Most in vivo electroporation protocols entail applying square-wave, or monotonically-decreasing pulses but relatively few have explored the use of pulsed ac fields. This study measures the efficiency of electroporation in human kidney embryonal cells, using pulsed ac electric fields of peak amplitude 30-200 kV m-1. The results indicate that optimum electroporation efficiencies of up to 70% can be achieved using pulses at frequencies of 20-160 kHz. Increasing the field strength results in higher electroporation efficiency, but also increases cell kill. This study confirms that efficient electroporation may be achieved using pulsed ac fields. This finding raises the possibility of a wider range of clinical and laboratory applications based on ac technology and avoiding the use of invasive needle electrodes

  11. Digitized quantitative electroencephalographic patterns applied as magnetic fields inhibit melanoma cell proliferation in culture.

    Science.gov (United States)

    Karbowski, Lukasz M; Harribance, Sean L; Buckner, Carly A; Mulligan, Bryce P; Koren, Stanley A; Lafrenie, Robert M; Persinger, Michael A

    2012-08-15

    Weak (1 μT) physiologically patterned magnetic fields produce changes in behavioral, physiological, and cellular activity. In the present experiments 12 temporal samples of the electroencephalographic anomaly and normal activity of a person (SLH) whose proximity reliably affected the brain activity of others were extracted from QEEG data, digitized, and presented as equivalent magnetic field patterns to B16 mouse melanoma cells. Only two of the patterns, both originating from the primary source (right temporal lobe) of the EEG anomaly reduced the cell growth by one-third compared to the other patterns extracted from his QEEG or sham field exposures. In previous experiments these EEG transients were also associated with marked increases in photon emissions from the right side of SLH's head. The results suggest that the intrinsic complexity of electroencephalographic patterns of some people, when amplified appropriately and applied as computer-generated magnetic fields in the three spatial planes, could diminish cancer cell growth. PMID:22750152

  12. 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

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

    Science.gov (United States)

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

    2014-01-01

    Exact explicit rogue-wave solutions of intricate structures are presented for the long-wave-short-wave resonance equation. These vector parametric solutions feature coupled dark- and bright-field counterparts of the Peregrine soliton. Numerical simulations show the robustness of dark and bright rogue waves in spite of the onset of modulational instability. Dark fields originate from the complex interplay between anomalous dispersion and the nonlinearity driven by the coupled long wave. This unusual mechanism, not available in scalar nonlinear wave equation models, can provide a route to the experimental realization of dark rogue waves in, for instance, negative index media or with capillary-gravity waves. PMID:24580164

  14. 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,...

  15. 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....

  16. Order reconstruction in inverse twisted nematic cell with an applied electric field

    Science.gov (United States)

    Sun, Yang; Ye, Wenjiang; Zhang, Zhidong

    2016-05-01

    Order reconstruction in an inverse twisted nematic (ITN) liquid crystal cell with an applied electric field is investigated based on Landau-de Gennes theory and the two-dimensional finite-difference iterative method. Twice eigenvalue exchange in three-axis layer configuration, thrice eigenvalue exchange in four-axis layer configuration, and negative order parameter uniaxial twisted state exist in this cell, which can be described by the order parameter tensor Q in equilibrium state. The twice eigenvalue exchange also has two degenerate configurations with reduced electric field E from 0.8 to 2.8 in 10ξ cell (ξ is the biaxial correlation length). Moreover, two critical cell gaps dc** = 7 ξ and dc* = 12 ξ are included in the study of the ITN cell. When d �**, only the eigenvalue change state exists. When d ≥ dc*, only a positive order parameter uniaxial twisted state exists near the threshold electric field. When dc** electric field. Comparison of the eigenvalue exchange solutions of different cell gaps of 5ξ, 10ξ, and 20ξ shows that smaller cell gap can inhibit the complexity of the eigenvalue exchange solution and reduce the number of axis layers. This research provides a theoretical basis for the change of multi-axis layer defect and promotes the concept of eigenvalue exchange.

  17. 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.

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

    Science.gov (United States)

    Youngstedt, Shawn D; Kline, Christopher E; Elliott, Jeffrey A; Zielinski, Mark R; 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 in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect. PMID:27103935

  19. Optical measurements of strong microwave fields with Rydberg atoms in a vapor cell

    CERN Document Server

    Anderson, David A; Gordon, Joshua A; Butler, Miranda L; Holloway, Christopher L; Raithel, Georg

    2016-01-01

    We present a spectral analysis of Rydberg atoms in strong microwave fields using electromagnetically induced transparency (EIT) as an all-optical readout. The measured spectroscopic response enables optical, atom-based electric field measurements of high-power microwaves. In our experiments, microwaves are irradiated into a room-temperature rubidium vapor cell. The microwaves are tuned near the two-photon 65D-66D Rydberg transition and reach an electric field strength of 230V/m, about 20% of the microwave ionization threshold of these atoms. A Floquet treatment is used to model the Rydberg level energies and their excitation rates. We arrive at an empirical model for the field-strength distribution inside the spectroscopic cell that yields excellent overall agreement between the measured and calculated Rydberg EIT-Floquet spectra. Using spectral features in the Floquet maps we achieve an absolute strong-field measurement precision of 6%.

  20. Optical Measurements of Strong Microwave Fields with Rydberg Atoms in a Vapor Cell

    Science.gov (United States)

    Anderson, D. A.; Miller, S. A.; Raithel, G.; Gordon, J. A.; Butler, M. L.; Holloway, C. L.

    2016-03-01

    We present a spectral analysis of Rydberg atoms in strong microwave fields using electromagnetically induced transparency (EIT) as an all-optical readout. The measured spectroscopic response enables optical, atom-based electric-field measurements of high-power microwaves. In our experiments, microwaves are irradiated into a room-temperature rubidium vapor cell. The microwaves are tuned near the two-photon 65 D -66 D Rydberg transition and reach an electric-field strength of 230 V /m , about 20% of the microwave-ionization threshold of these atoms. A Floquet treatment is used to model the Rydberg-level energies and their excitation rates. We arrive at an empirical model for the field-strength distribution inside the spectroscopic cell that yields excellent overall agreement between the measured and calculated Rydberg EIT-Floquet spectra. Using spectral features in the Floquet maps, we achieve an absolute strong-field measurement precision of 6%.

  1. 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

  2. Effect of the combined action of gamma radiation and static fields in human cells

    International Nuclear Information System (INIS)

    Our goal 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 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 did not induce toxicity. Immunofluorescence runs carried out in irradiated normal MRC5 cell line of human lung fibroblast have quantified the expression of the g-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 showed 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. (author)

  3. 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...

  4. 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

  5. An ultra-bright atom laser

    International Nuclear Information System (INIS)

    We present a novel, ultra-bright atom laser and an ultra-cold thermal atom beam. Using rf-radiation we strongly couple the magnetic hyperfine levels of 87Rb atoms in a trapped Bose–Einstein condensate. The resulting time-dependent adiabatic potential forms a trap, which at low rf-frequencies opens just below the condensate and thus allows an extremely bright well-collimated atom laser beam to emerge. As opposed to traditional atom lasers based on weak coupling of the magnetic hyperfine levels, this technique allows us to outcouple atoms at an arbitrarily large rate. We achieve a flux of 4×107 atom s-1, a seven fold increase compared to the brightest atom lasers to date. Furthermore, we demonstrate by two orders of magnitude the coldest thermal atom beam (200 nK). (paper)

  6. 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.

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

    International Nuclear Information System (INIS)

    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. (paper)

  8. 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.

  9. 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.

  10. 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.

  11. Spectral Characterization of Bright Materials on Vesta

    Science.gov (United States)

    Capaccioni, Fabrizio; DeSanctis, M. C.; Ammannito, E.; Li, Jian-Yang; Longobardo, A.; Mittlefehldt, David W.; Palomba, E.; Pieters, C. M.; Schroeder, S. E.; Tosi, F.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.

    2012-01-01

    The surface of Vesta, as observed by the camera and imaging spectrometer onboard the Dawn spacecraft, displays large surface diversity in terms of its geology and mineralogy with noticeably dark and bright areas on the surface often associated with various geological features and showing remarkably different forms. Here we report our initial attempt to spectrally characterize the areas that are distinctively brighter than their surroundings.

  12. 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...

  13. Bright vortex solitons in Bose Condensates

    OpenAIRE

    Adhikari, Sadhan K.

    2003-01-01

    We suggest the possibility of observing and studying bright vortex solitons in attractive Bose-Einstein condensates in three dimensions with a radial trap. Such systems lie on the verge of critical stability and we discuss the conditions of their stability. We study the interaction between two such solitons. Unlike the text-book solitons in one dimension, the interaction between two radially trapped and axially free three-dimensional solitons is inelastic in nature and involves exchange of pa...

  14. Mesenchymal stem cell-induced 3D displacement field of cell-adhesion matrices with differing elasticities.

    Science.gov (United States)

    Morita, Yasuyuki; Kawase, Naoki; Ju, Yang; Yamauchi, Takashi

    2016-07-01

    Cells maintain homeostasis and perform various functions by interacting mechanically with a cell-adhesive matrix. Regarding cellular differentiation, it has been found that matrix elasticity can determine the differentiation lineage of mesenchymal stem cells (MSCs). Direct quantitative measurements of the mechanical interaction between MSCs and matrix for differentiation, however, have yet to be reported. Herein, the displacement field of the cell-adhesive matrix was observed quantitatively using a digital volume correlation (DVC) method. Maximum displacement and cellular traction stress were analyzed when the MSC differentiated into a neuron-like cell or an osteoblast-like cell on a soft or hard elastic matrix, respectively. The function of non-muscle myosin II (NMM II), which plays an important role in intracellular cytoskeletal dynamics, was investigated during cellular differentiation. The mechanical interaction (maximum displacement and subjected area of the matrix) between the cell and matrix was dependent on matrix elasticity. It has also been shown that the mechanical interaction between the intracellular cytoskeleton and cell-adhesion matrix is indispensable for cellular differentiation. This work provides the first quantitative visualization of the mechanical interaction between MSCs and the cell-adhesion matrix for differentiation. PMID:26945874

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

    International Nuclear Information System (INIS)

    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-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.

  16. Origin of bright flares in SFXTs

    CERN Document Server

    Postnov, K; Sidoli, L; Paizis, A

    2014-01-01

    In the settling accretion theory, which is applicable to quasi-spherical accreting slowly rotating magnetized neutron stars with X-ray luminosity $L_x\\lesssim 4\\times 10^{36}$~erg/s, bright X-ray flares ($\\sim 10^{38}-10^{40}$~ergs) observed in supergiant fast X-ray transients (SFXT) may be produced by sporadic capture of magnetized stellar-wind plasma from the early-type supergiant. At sufficiently low steady accretion rates ($\\lesssim 10^{15}$~g/s) through the shell around the neutron star magnetosphere at the settling accretion stage, magnetic reconnection can temporarily enhance the magnetospheric plasma entry rate, resulting in copious production of X-ray photons, strong Compton cooling, and ultimately in unstable accretion of the entire shell. A bright flare develops on the free-fall time scale in the shell, $R_B^{3/2}/\\sqrt{GM}\\sim 10^3-10^4$~s ($R_B$ is the classical Bondi capture radius), and the typical energy released in an SFXT bright flare corresponds to the mass of the shell.

  17. 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

  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. The surface brightness of spiral galaxies: Pt. 4

    International Nuclear Information System (INIS)

    Using measurements from IRAS correlations are found between optical surface brightness and both infrared-to-optical flux ratio and infrared colour temperature, in the sense that galaxies with high surface brightness have higher FIR emission and higher temperatures. (author)

  20. 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:.

  1. 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.

  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. Driven-mirror formation of a two-cell field-reversed configuration

    International Nuclear Information System (INIS)

    Improved plasma confinement on open field lines in field reversed configurations (FRC's) may prove to be of importance, as suggested by recent experiments on the control of the n=2 rotational instability. Multiple mirrors have been suggested as one way to accomplish this improved confinement. To study the formation of multiple-cell FRC's, driven magnetic mirrors have been added to the High Beta Q Machine (HBQM) at three axial positions along the theta pinch coil. We report here on measurements of the reconnection process in the region between the cells and also at one end of the coil

  5. 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...

  6. 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...

  7. Star formation and the surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    The (blue) surface brightness of spiral galaxies is significantly correlated with their Hα linewidth. This can be most plausibly interpreted as a correlation of surface brightness with star formation rate. There is also a significant difference in surface brightness between galaxies forming stars in a grand design spiral pattern and those with floc star formation regions. (author)

  8. 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.

  9. Reversible and irreversible electroporation of cell suspensions flowing through a localized DC electric field.

    Science.gov (United States)

    Korohoda, Włodzimierz; Grys, Maciej; Madeja, Zbigniew

    2013-03-01

    Experiments on reversible and irreversible cell electroporation were carried out with an experimental setup based on a standard apparatus for horizontal electrophoresis, a syringe pump with regulated cell suspension flow velocity and a dcEF power supply. Cells in suspension flowing through an orifice in a barrier inserted into the electrophoresis apparatus were exposed to defined localized dcEFs in the range of 0-1000 V/cm for a selected duration in the range 10-1000 ms. This method permitted the determination of the viability of irreversibly electroperforated cells. It also showed that the uptake by reversibly electroperforated cells of fluorescent dyes (calcein, carboxyfluorescein, Alexa Fluor 488 Phalloidin), which otherwise do not penetrate cell membranes, was dependent upon the dcEF strength and duration in any given single electrical field exposure. The method yields reproducible results, makes it easy to load large volumes of cell suspensions with membrane non-penetrating substances, and permits the elimination of irreversibly electroporated cells of diameter greater than desired. The results concur with and elaborate on those in earlier reports on cell electroporation in commercially available electroporators. They proved once more that the observed cell perforation does not depend upon the thermal effects of the electric current upon cells. In addition, the method eliminates many of the limitations of commercial electroporators and disposable electroporation chambers. It permits the optimization of conditions in which reversible and irreversible electroporation are separated. Over 90% of reversibly electroporated cells remain viable after one short (less than 400 ms) exposure to the localized dcEF. Experiments were conducted with the AT-2 cancer prostate cell line, human skin fibroblasts and human red blood cells, but they could be run with suspensions of any cell type. It is postulated that the described method could be useful for many purposes in

  10. 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...

  11. 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 ...

  12. Multiwavelength investigations of co-evolution of bright custer galaxies

    CERN Document Server

    Hashimoto, Yasuhiro; Boehringer, Hans

    2014-01-01

    We report a systematic multi-wavelength investigation of environments of the brightest cluster galaxies (BCGs), using the X-ray data from the Chandra archive, and optical images taken with 34'x 27' field-of-view Subaru Suprime-Cam. Our goal is to help understand the relationship between the BCGs and their host clusters, and between the BCGs and other galaxies, to eventually address a question of the formation and co-evolution of BCGs and the clusters. Our results include: 1) Morphological variety of BCGs, or the second or the third brightest galaxy (BCG2, BCG3), is comparable to that of other bright red sequence galaxies, suggesting that we have a continuous variation of morphology between BCGs, BCG2, and BCG3, rather than a sharp separation between the BCG and the rest of the bright galaxies. 2) The offset of the BCG position relative to the cluster centre is correlated to the degree of concentration of cluster X-ray morphology (Spearman rho = -0.79), consistent with an interpretation that BCGs tend to be of...

  13. 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...

  14. 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...

  15. 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.

  16. Differentiation imbalance in single Oesophageal progenitor cells causes clonal immortalization and field change

    Science.gov (United States)

    Alcolea, Maria P.; Greulich, Philip; Wabik, Agnieszka; Frede, Julia; Simons, Benjamin D.; Jones, Philip H.

    2014-01-01

    Multiple cancers may arise from within a clonal region of preneoplastic epithelium, a phenomenon termed ‘field change’1, 2. However, it is not known how field change develops. Here we investigate this question using lineage tracing to track the behaviour of scattered single oesophageal epithelial progenitor cells expressing a mutation that inhibits the Notch signaling pathway. Notch is frequently subject to inactivating mutation in squamous cancers3-6. Quantitative analysis reveals that cell divisions which produce two differentiated daughters are absent in mutant progenitors. As a result mutant clones are no longer lost by differentiation and become functionally immortal. In addition, mutant cells promote the differentiation of neighbouring wild type cells, which are then lost from the tissue. These effects lead to clonal expansion, with mutant cells eventually replacing the entire epithelium. Furthermore, Notch inhibition in progenitors carrying p53 stabilizing mutations creates large confluent regions of doubly mutant epithelium. Field change is thus a consequence of imbalanced differentiation in individual progenitor cells. PMID:24814514

  17. 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 .

  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. 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

  20. Orientation of red blood cells and rouleaux disaggregation in interference laser fields.

    Science.gov (United States)

    Kruchenok, J V; Bushuk, S B; Kurilo, G I; Nemkovich, N A; Rubinov, A N

    2005-01-01

    The effect of interference laser fields on red blood cells (RBCs) was investigated both theoretically and experimentally. The optical trapping and orientation of individual RBC in interference fringes were observed. It was found that RBC rouleaux undergo disaggregation under the action of interference laser fields. To describe the effect of RBC orientation in interference fringes, we used the equation for torque exerted on a discoid dielectric particle in a gradient light field. The experimental results are in agreement with the predictions of the developed theoretical model. PMID:23345885

  1. 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.

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

    International Nuclear Information System (INIS)

    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. (author)

  3. Conventional and 360 degree electron tomography of a micro-crystalline silicon solar cell

    DEFF Research Database (Denmark)

    Duchamp, Martial; Ramar, Amuthan; Kovács, András; Kasama, Takeshi; Haug, F. -J.; Newcomb, S. B.; Ballif, C.; Dunin-Borkowski, Rafal E.

    2011-01-01

    Bright-field (BF) and annular dark-field (ADF) electron tomography in the transmission electron microscope (TEM) are used to characterize elongated porous regions or cracks (simply referred to as cracks thereafter) in micro-crystalline silicon (μc-Si:H) solar cell. The limitations of inferring th...

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. The Bright Quasar 3C 273

    OpenAIRE

    Courvoisier, Thierry J. -L.

    1998-01-01

    We review the observed properties of the bright quasar 3C~273 and discuss the implications of these observations for the emission processes and in view of gaining a more global understanding of the object. Continuum and line emission are discussed. The emission from the radio domain to gamma rays are reviewed. Emphasis is given to variability studies across the spectrum as a means to gain some understanding on the relationships between the emission components. 3C~273 has a small scale jet and...

  11. 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...

  12. Design of flow-field patterns for proton exchange membrane fuel cell application

    International Nuclear Information System (INIS)

    Fuel cells are electrochemical devices that produce electricity at high efficiency without combustion. Fuel cells are emerging as viable candidates as power sources in many applications, including road vehicles, small-scale power stations, and possibly even portable electronics. This paper addresses the design of flow-field patterns for proton exchange membrane fuel cell (PEMFC). The PEMFC is a low-temperature fuel cell, in which a proton conductive polymer membrane is used as the electrolyte. In PEMFC, flow-field pattern is one important thing that effects the performance of PEMFC. This paper present three types of flow-field pattern that will be consider to be testing using CFD analysis and by experimental. The design look detail on to their shape and dimension to get the best pattern in term of more active electrode area compare to electrode area that will be used. Another advantage and disadvantage for these three type of flow-field patterns from literature also compared in this paper

  13. Modulation of monocytic leukemia cell function and survival by highgradient magnetic fields and mathematical modeling studies

    Czech Academy of Sciences Publication Activity Database

    Zablotskyy, Vitaliy A.; Syrovets, T.; Schmidt, Z.W.; Dejneka, Alexandr; Simmet, T.

    2014-01-01

    Roč. 35, č. 10 (2014), s. 3164-3171. ISSN 0142-9612 Grant ostatní: AV ČR(CZ) M100101219 Institutional support: RVO:68378271 Keywords : magnetic field * cell proliferation * leukemia * apoptosis * modeling Subject RIV: BO - Biophysics Impact factor: 8.557, year: 2014

  14. Understanding dielectrophoretic trapping of neuronal cells: modelling electric field, electrode-liquid interface and fluid flow

    International Nuclear Information System (INIS)

    By application of dielectrophoresis neuronal cells can be trapped successfully. Several trapping experiments have been performed using a quadrupole electrode structure at different amplitudes (1, 3, and 5 Vpp) and frequencies (10-50 MHz). Due to the high conductivity of the suspending medium negative dielectrophoretic forces are created. The dielectrophoretic force is determined by the gradient of the electric field. However, the electrode-liquid interfaces are responsible for decreased electric field strengths, and thus decreased field gradients, inside the medium, especially at lower frequencies. Circuit modelling is used to determine the frequency-dependent electric field inside the medium. The creation of an electric field in high conductivity of the medium results in local heating, which in turn induces fluid flow. This flow also drives the neurons and was found to enhance the trapping effect of the dielectrophoretic force. With the use of finite element modelling, this aspect was investigated. The results show that the dielectrophoretic force is dominating just above the substrate. When the upward dielectrophoretic force is large enough to levitate the cells, they may be dragged along with the fluid flow. The result is that more cells may be trapped than expected on the basis of dielectrophoresis alone. (author)

  15. 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.

  16. Acute exposure to a 60 Hz magnetic field increases DNA strand breaks in rat brain cells

    Energy Technology Data Exchange (ETDEWEB)

    Lai, H.; Singh, N.P. [Univ. of Washington, Seattle, WA (United States)

    1997-05-01

    Acute exposure of rats to a 60 Hz magnetic field caused a dose-dependent increase in DNA strand breaks in brain cells of the animals (assayed by a microgel electrophoresis method at 4 h postexposure). An increase in single-strand DNA breaks was observed after exposure to magnetic fields of 0.1, 0.25, and 0.5 mT, whereas an increase in double-strand DNA breaks was observed at 0.25 and 0.5 mT. Because DNA strand breaks may affect cellular functions, lead to carcinogenesis and cell death, and be related to onset of neurodegenerative diseases, the data may have important implications for the possible health effects of exposure to 60 Hz magnetic fields.

  17. Bright tunable femtosecond x-ray emission from laser irradiated micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Tong-Pu, E-mail: tongpu@nudt.edu.cn; Hu, Li-Xiang; Yin, Yan; Shao, Fu-Qiu; Zhuo, Hong-Bin; Ma, Yan-Yun; Yang, Xiao-Hu [College of Science, National University of Defense Technology, Changsha 410073 (China); Luo, Wen [School of Nuclear Science and Technology, University of South China, Hengyang 421001 (China); Pukhov, Alexander [Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf (Germany)

    2014-09-15

    It is demonstrated that bright femtosecond X-rays can be obtained by irradiating a moderate laser onto a helium micro-droplet. The laser ponderomotive force continuously sweeps electrons from the droplets and accelerates them forward. The electrons exposed in the outrunning laser field oscillate transversely and emit photons in the forward direction. The total flux of photons with energies above 1 keV is as high as 10{sup 9}/shot which is about 10-fold enhancement compared with betatron oscillation under similar laser conditions. The maximum achieved peak brightness is up to 10{sup 21} photons/s/mm{sup 2}/mrad{sup 2}/0.1%BW. By adjusting laser and droplet parameters, we can get tunable X-rays with required brightness and energy.

  18. Dynamics of cell and tissue growth acquired by means of extended field of view lensfree microscopy.

    Science.gov (United States)

    Momey, F; Coutard, J-G; Bordy, T; Navarro, F; Menneteau, M; Dinten, J-M; Allier, C

    2016-02-01

    In this paper, we discuss a new methodology based on lensfree imaging to perform wound healing assay with unprecedented statistics. Our video lensfree microscopy setup is a simple device featuring only a CMOS sensor and a semi coherent illumination system. Yet it is a powerful mean for the real-time monitoring of cultivated cells. It presents several key advantages, e.g. integration into standard incubator, compatibility with standard cell culture protocol, simplicity and ease of use. It can perform the follow-up in a large field of view (25 mm(2)) of several crucial parameters during the culture of cells i.e. their motility, their proliferation rate or their death. Consequently the setup can gather large statistics both in space and time. Here we uses this facility in the context of wound healing assay to perform label-free measurements of the velocities of the fronts of proliferation of the cell layer as a function of time by means of particle image velocimetry (PIV) processing. However, for such tissue growth experiments, the field of view of 25 mm(2) remains not sufficient and results can be biased depending on the position of the device with respect to the recipient of the cell culture. Hence, to conduct exhaustive wound healing assays, we propose to enlarge the field of view up to 10 cm(2) through a raster scan, by moving the source/sensor with respect to the Petri dish. We have performed acquisitions of wound healing assay (keratinocytes HaCaT) both in real-time (25 mm(2)) and in final point (10 cm(2)) to assess the combination of velocimetry measurements and final point wide field imaging. In the future, we aim at combining directly our extended field of view acquisitions (>10 cm(2)) with real time ability inside the incubator. PMID:26977359

  19. 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.)

  20. Dual-modality wide-field photothermal quantitative phase microscopy and depletion of cell populations

    Science.gov (United States)

    Turko, Nir A.; Barnea, Itay; Blum, Omry; Korenstein, Rafi; Shaked, Natan T.

    2015-03-01

    We review our dual-modality technique for quantitative imaging and selective depletion of populations of cells based on wide-field photothermal (PT) quantitative phase imaging and simultaneous PT cell extermination. The cells are first labeled by plasmonic gold nanoparticles, which evoke local plasmonic resonance when illuminated by light in a wavelength corresponding to their specific plasmonic resonance peak. This reaction creates changes of temperature, resulting in changes of phase. This phase changes are recorded by a quantitative phase microscope (QPM), producing specific imaging contrast, and enabling bio-labeling in phase microscopy. Using this technique, we have shown discrimination of EGFR over-expressing (EGFR+) cancer cells from EGFR under-expressing (EGFR-) cancer cells. Then, we have increased the excitation power in order to evoke greater temperatures, which caused specific cell death, all under real-time phase acquisition using QPM. Close to 100% of all EGFR+ cells were immediately exterminated when illuminated with the strong excitation beam, while all EGFR- cells survived. For the second experiment, in order to simulate a condition where circulating tumor cells (CTCs) are present in blood, we have mixed the EGFR+ cancer cells with white blood cells (WBCs) from a healthy donor. Here too, we have used QPM to observe and record the phase of the cells as they were excited for selective visualization and then exterminated. The WBCs survival rate was over 95%, while the EGFR+ survival rate was under 5%. The technique may be the basis for real-time detection and controlled treatment of CTCs.

  1. 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.

  2. 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.'

  3. 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

  4. Effect of Pulsatile Electric Field on Cultured Muscle Cells in Vitro

    Directory of Open Access Journals (Sweden)

    Aki Nakajima

    2012-02-01

    Full Text Available An effect of an electric field on proliferation and on differentiation of cultured muscle cells has been studied in vitro. C2C12 (the mouse myoblast cell line originated with the cross-striated muscle of C3H mouse was exposed to electric stimuli. In the first experiment, the adhered cells were exposed to the electric field between two electrodes made of platinum wire of 0.2 mm diameter dipped in the medium at 37 degrees Celsius for 72 hours. The electric pulses at a period of one second with a pulse width of 0.1 second were generated with a function generator. Variation was made on the pulse amplitude < 12 V. The number of adhered cells was counted after exposure to electric stimulation. In the second experiment, the cells were cultivated for 96 hours without electric stimulation in an incubator, after electric stimulation of 0.1 V for 72 hours. After incubation, the movement of myotubes was observed with electric stimulation at a period of one second with a pulse width of one millisecond of 30 V. The experimental results show that cells adhere and proliferate under electric pulses lower than 8 V, and that differentiation accelerates with the electric pulses of 0.1 V.

  5. 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.

  6. 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

  7. Induction of Oxidation in Living Cells by Time-Varying Electromagnetic Fields

    Science.gov (United States)

    Stolc, Viktor

    2015-01-01

    We are studying how biological systems can harness quantum effects of time varying electromagnetic (EM) waves as the time-setting basis for universal biochemical organization via the redox cycle. The effects of extremely weak EM field on the biochemical redox cycle can be monitored through real-time detection of oxidation-induced light emissions of reporter molecules in living cells. It has been shown that EM fields can also induce changes in fluid transport rates through capillaries (approximately 300 microns inner diameter) by generating annular proton gradients. This effect may be relevant to understanding cardiovascular dis-function in spaceflight, beyond the ionosphere. Importantly, we show that these EM effects can be attenuated using an active EM field cancellation device. Central for NASA's Human Research Program is the fact that the absence of ambient EM field in spaceflight can also have a detrimental influence, namely via increased oxidative damage, on DNA replication, which controls heredity.

  8. 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

  9. 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

  10. 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.

  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

    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.

  12. Meso-beta scale perturbations of the wind field by thunderstorm cells

    Science.gov (United States)

    Ulanski, S. L.; Heymsfield, G. M.

    1986-01-01

    Data from the high density storm-scale rawinsonde network of the Severe Environmental Storms and Mesoscale Experiment revealed temporal and spatial changes in the divergence fields of the troposphere in response to severe storm evolution on May 2, 1979; these changes were detectable on the meso-beta scale. This unique set of data was subsequently used to study the evolution of the wind, divergence and vertical motion fields in the presence of intense convection. Mid- and upper-tropospheric divergence was superimposed over low-level convergence. The divergence, which has a maximum value of .0004/s, occurred 75 to 100 km upwind as well as over the tornadic cells. To the south of the storm cells, the kinematic pattern was in reverse, upper level convergence was superimposed over low-level divergence. A vertical motion doublet was found to ascend over the squall line and descend about 70 km south of the squall line. It is suggested that the following effects are accountable for the nature of the kinematic fields: (1) blocking of tropospheric environmental flow by the storm cells, (2) anvil outflows, particularly from the tornadic cells, and (3) divergence from the exit region of the jet stream.

  13. New Distant Comet Headed for Bright Encounter

    Science.gov (United States)

    1995-08-01

    How Impressive Will Comet Hale-Bopp Become in 1997 ? A very unusual comet was discovered last month, on its way from the outer reaches of the solar system towards the Sun. Although it is still situated beyond the orbit of Jupiter, it is so bright that it can be observed in even small telescopes. It has been named `Hale-Bopp' after the discoverers and is already of great interest to cometary astronomers. No less than seven telescopes have been used at the ESO La Silla observatory for the first observations of the new object. Together with data gathered at other sites, their aim is to elucidate the nature of this comet and also to determine whether there is reason to hope that it will become a bright and beautiful object in the sky from late 1996 and well into 1997. Further observations are now being planned at ESO and elsewhere to monitor closely the behaviour of this celestial visitor during the coming months. Discovery circumstances The comet was discovered on 23 July 1995, nearly simultaneously by two American amateur astronomers, Alan Hale of Cloudcroft (New Mexico) and Thomas Bopp of Glendale (Arizona). Although the chronology is slightly uncertain, it appears that Hale first saw it some 10 - 20 minutes before Bopp, at 06:10 - 06:15 UT on that day. In any case, he informed the IAU Central Bureau for Astronomical Telegrams (CBAT) in Cambridge (Massachussetts) about his discovery by email already at 06:50 UT, while Bopp's message was filed more than 2 hours later, after he had driven back to his home, 140 km from where he had been observing. Upon receipt of these messages, Brian Marsden at the CBAT assigned the designation `1995 O1' (indicating that it is the first comet found in the second half of July 1995). After further sightings had been made by other observers, and according to the venerable astronomical tradition, the new object was named after the discoverers. The magnitude, reported as 10.5 by Hale, is not unusual for a comet that is discovered within

  14. 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.

  15. Review of bipolar plates in PEM fuel cells: flow field designs, materials and manufacturing techniques

    International Nuclear Information System (INIS)

    The polymer electrolyte membrane (PEM) fuel cell is a promising candidate as zero-emission power source for transport and stationary cogeneration applications due to its high efficiency, low temperature operation, high power density, fast start-up, and system robustness. Bipolar plate is a vital component of PEM fuel cells, which supplies fuel and oxidant to reactive sites, removes reaction products, collects produced current and provides mechanical support for the cells in the stack. Bipolar plates constitute more than 60% of the weight and 30% of the total cost in a fuel cell stack. For this reason, the weight, volume and cost of the fuel cell stack can be reduced significantly by improving layout configuration of flow field and use of light weight materials. Different combinations of materials, flow field layouts and fabrication techniques have been developed for these plates to achieve aforementioned functions efficiently, with the aim of obtaining high performance and economic advantages. The present paper presents a comprehensive review of these combinations and their pros and cons. (author)

  16. A novel ultrasonic resonance field device for the retention of animal cells.

    Science.gov (United States)

    Doblhoff-Dier, O; Gaida, T; Katinger, H; Burger, W; Gröschl, M; Benes, E

    1994-01-01

    This article describes two types of flow-through cell retention devices based on the concept of layered piezoelectric resonators. A single-chamber device is compared to a novel optimized steam-sterilizable prototype ultrasonic cell separator with improved acoustic design and an integrated cooling circuit, eliminating the problem of local temperature increase caused by the high amplitudes necessary to achieve the separation of animal cells with low acoustic contrast. This setup yields highly reproducible results and is ideal for studying the long-term effects of ultrasonic sound fields and separation efficiency. The novel two-chamber system has the potential for scaleability due to the reduction in thermal and acoustic flow, increased field stability, and separation efficiency. Finally, the effect of power input on separation and cell viability is reported. Such flow-through cell retention systems could be used as systems to retain biomass within the fermentor or as a substitute for centrifugation, with the major advantage of eliminating high-speed rotational motion. PMID:7765096

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. 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...

  10. Photoinduced Charge Transport in a BHJ Solar Cell Controlled by an External Electric Field

    OpenAIRE

    Yongqing Li; Yanting Feng; Mengtao Sun

    2015-01-01

    This study investigated theoretical photoinduced charge transport in a bulk heterojunction (BHJ) solar cell controlled by an external electric field. Our method for visualizing charge difference density identified the excited state properties of photoinduced charge transfer, and the charge transfer excited states were distinguished from local excited states during electronic transitions. Furthermore, the calculated rates for the charge transfer revealed that the charge transfer was strongly i...

  11. Fast wide-field photothermal and quantitative phase cell imaging with optical lock-in detection

    OpenAIRE

    Eldridge, Will J.; Meiri, Amihai; Sheinfeld, Adi; Rinehart, Matthew T.; Wax, Adam

    2014-01-01

    We present a fast, wide-field holography system for detecting photothermally excited gold nanospheres with combined quantitative phase imaging. An interferometric photothermal optical lock-in approach (POLI) is shown to improve SNR for detecting nanoparticles (NPs) on multiple substrates, including a monolayer of NPs on a silanized coverslip, and NPs bound to live cells. Furthermore, the set up allowed for co-registered quantitative phase imaging (QPI) to be acquired in an off-axis holographi...

  12. 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.

  13. 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...

  14. Study of Three-Dimensional Image Brightness Loss in Stereoscopy

    Directory of Open Access Journals (Sweden)

    Hsing-Cheng Yu

    2015-10-01

    Full Text Available When viewing three-dimensional (3D images, whether in cinemas or on stereoscopic televisions, viewers experience the same problem of image brightness loss. This study aims to investigate image brightness loss in 3D displays, with the primary aim being to quantify the image brightness degradation in the 3D mode. A further aim is to determine the image brightness relationship to the corresponding two-dimensional (2D images in order to adjust the 3D-image brightness values. In addition, the photographic principle is used in this study to measure metering values by capturing 2D and 3D images on television screens. By analyzing these images with statistical product and service solutions (SPSS software, the image brightness values can be estimated using the statistical regression model, which can also indicate the impact of various environmental factors or hardware on the image brightness. In analysis of the experimental results, comparison of the image brightness between 2D and 3D images indicates 60.8% degradation in the 3D image brightness amplitude. The experimental values, from 52.4% to 69.2%, are within the 95% confidence interval

  15. Separation of platelets from other blood cells in continuous-flow by dielectrophoresis field-flow-fractionation

    OpenAIRE

    Piacentini, Niccolò; Mernier, Guillaume; Tornay, Raphaël; Renaud, Philippe

    2011-01-01

    We present a microfluidic device capable of separating platelets from other blood cells in continuous flow using dielectrophoresis field-flow-fractionation. The use of hydrodynamic focusing in combination with the application of a dielectrophoretic force allows the separation of platelets from red blood cells due to their size difference. The theoretical cell trajectory has been calculated by numerical simulations of the electrical field and flow speed, and is in agreement with the experiment...

  16. 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.

  17. The Role of Direct Current Electric Field-Guided Stem Cell Migration in Neural Regeneration.

    Science.gov (United States)

    Yao, Li; Li, Yongchao

    2016-06-01

    Effective directional axonal growth and neural cell migration are crucial in the neural regeneration of the central nervous system (CNS). Endogenous currents have been detected in many developing nervous systems. Experiments have demonstrated that applied direct current (DC) electric fields (EFs) can guide axonal growth in vitro, and attempts have been made to enhance the regrowth of damaged spinal cord axons using DC EFs in in vivo experiments. Recent work has revealed that the migration of stem cells and stem cell-derived neural cells can be guided by DC EFs. These studies have raised the possibility that endogenous and applied DC EFs can be used to direct neural tissue regeneration. Although the mechanism of EF-directed axonal growth and cell migration has not been fully understood, studies have shown that the polarization of cell membrane proteins and the activation of intracellular signaling molecules are involved in the process. The application of EFs is a promising biotechnology for regeneration of the CNS. PMID:27108005

  18. 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

  19. 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...

  20. Static magnetic fields modulate X-ray-induced DNA damage in human glioblastoma primary cells

    International Nuclear Information System (INIS)

    Although static magnetic fields (SMFs) are used extensively in the occupational and medical fields, few comprehensive studies have investigated their possible genotoxic effect and the findings are controversial. With the advent of magnetic resonance imaging-guided radiation therapy, the potential effects of SMFs on ionizing radiation (IR) have become increasingly important. In this study we focused on the genotoxic effect of 80 mT SMFs, both alone and in combination with (i.e. preceding or following) X-ray (XR) irradiation, on primary glioblastoma cells in culture. The cells were exposed to: (1) SMFs alone; (2) XRs alone; (3) XR, with SMFs applied during recovery; (4) SMFs both before and after XR irradiation. XR-induced DNA damage was analyzed by Single Cell Gel Electrophoresis assay (comet assay) using statistical tools designed to assess the tail DNA (TD) and tail length (TL) as indicators of DNA fragmentation. Mitochondrial membrane potential, known to be affected by IR, was assessed using the JC-1 mitochondrial probe. Our results showed that exposure of cells to 5 Gy of XR irradiation alone led to extensive DNA damage, which was significantly reduced by post-irradiation exposure to SMFs. The XR-induced loss of mitochondrial membrane potential was to a large extent averted by exposure to SMFs. These data suggest that SMFs modulate DNA damage and/or damage repair, possibly through a mechanism that affects mitochondria. (author)

  1. 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 Zhengping

    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.

  2. 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

  3. The relation between isolated tree brightness temperature and grass background brightness temperature

    Science.gov (United States)

    Krusinger, A. E.

    1983-08-01

    This study involves thermal infrared measurement for the determination of the diurnal and seasonal aspects of the relations between isolated evergreen tress and a cut grass background and between a large truck brightness temperature and cut grass, uncut grass, and bare soil backgrounds. Seasonal changes in the tree brightness temperature-background brightness temperature contrast ranged from 4 to 5 C in February and March to 1 to 2 C in July. At night, the thermal contrast between trees and background was found to vary inversely with long wave incoming radiation, which is a measure of cloudiness. A study of the change in the thermal contrast during the night showed that, during clear weather, the contrast was at a peak a few hours after sundown and decreased the rest of the night. In overcast conditions, a reduced contrast peak occurred at sundown and very gradually diminished through the night. Isothermal conditions were found to occur in the early mornings, and the time of these occurrences changed seasonally, in a systematic manner.

  4. 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%...

  5. 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

  6. 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.

  7. 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

  8. 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.

  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. Color and brightness uniformity compensation of a multi-projection 3D display

    Science.gov (United States)

    Lee, Jin-Ho; Park, Juyong; Nam, Dongkyung; Park, Du-Sik

    2015-09-01

    Light-field displays are good candidates in the field of glasses-free 3D display for showing real 3D images without decreasing the image resolution. Light-field displays can create light rays using a large number of projectors in order to express the natural 3D images. However, in light-field displays using multi-projectors, the compensation is very critical due to different characteristics and arrangement positions of each projector. In this paper, we present an enhanced 55- inch, 100-Mpixel multi-projection 3D display consisting of 96 micro projectors for immersive natural 3D viewing in medical and educational applications. To achieve enhanced image quality, color and brightness uniformity compensation methods are utilized along with an improved projector configuration design and a real-time calibration process of projector alignment. For color uniformity compensation, projected images from each projector are captured by a camera arranged in front of the screen, the number of pixels based on RGB color intensities of each captured image is analyzed, and the distributions of RGB color intensities are adjusted by using the respective maximum values of RGB color intensities. For brightness uniformity compensation, each light-field ray emitted from a screen pixel is modeled by a radial basis function, and compensating weights of each screen pixel are calculated and transferred to the projection images by the mapping relationship between the screen and projector coordinates. Finally, brightness compensated images are rendered for each projector. Consequently, the display shows improved color and brightness uniformity, and consistent, exceptional 3D image quality.

  11. Quiet-Sun Network Bright Point Phenomena with Sigmoidal Signatures

    Science.gov (United States)

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.; Champey, P. R.

    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.

  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. Photometry of very bright stars with Kepler and K2 smear data

    Science.gov (United States)

    Pope, B. J. S.; White, T. R.; Huber, D.; Murphy, S. J.; Bedding, T. R.; Caldwell, D. A.; Sarai, A.; Aigrain, S.; Barclay, T.

    2016-01-01

    High-precision time series photometry with the Kepler satellite has been crucial to our understanding both of exoplanets, and via asteroseismology, of stellar physics. After the failure of two reaction wheels, the Kepler satellite has been repurposed as Kepler-2 (K2), observing fields close to the ecliptic plane. As these fields contain many more bright stars than the original Kepler field, K2 provides an unprecedented opportunity to study nearby objects amenable to detailed follow-up with ground-based instruments. Due to bandwidth constraints, only a small fraction of pixels can be downloaded, with the result that most bright stars which saturate the detector are not observed. We show that engineering data acquired for photometric calibration, consisting of collateral `smear' measurements, can be used to reconstruct light curves for bright targets not otherwise observable with Kepler/K2. Here we present some examples from Kepler Quarter 6 and K2 Campaign 3, including the δ Scuti variables HD 178875 and 70 Aqr, and the red giant HR 8500 displaying solar-like oscillations. We compare aperture and smear photometry where possible, and also study targets not previously observed. These encouraging results suggest this new method can be applied to most Kepler and K2 fields.

  14. 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)

  15. 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

  16. Local Field Potentials Encode Place Cell Ensemble Activation during Hippocampal Sharp Wave Ripples.

    Science.gov (United States)

    Taxidis, Jiannis; Anastassiou, Costas A; Diba, Kamran; Koch, Christof

    2015-08-01

    Whether the activation of spiking cell ensembles can be encoded in the local field potential (LFP) remains unclear. We address this question by combining in vivo electrophysiological recordings in the rat hippocampus with realistic biophysical modeling, and explore the LFP of place cell sequence spiking ("replays") during sharp wave ripples. We show that multi-site perisomatic LFP amplitudes, in the ∼150-200 Hz frequency band, reliably reflect spatial constellations of spiking cells, embedded within non-spiking populations, and encode activation of local place cell ensembles during in vivo replays. We find spatiotemporal patterns in the LFP, which remain consistent between sequence replays, in conjunction with the ordered activation of place cell ensembles. Clustering such patterns provides an efficient segregation of replay events from non-replay-associated ripples. This work demonstrates how spatiotemporal ensemble spiking is encoded extracellularly, providing a window for efficient, LFP-based detection and monitoring of structured population activity in vivo. PMID:26247865

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Bright visible light emission from graphene

    Science.gov (United States)

    Kim, Young Duck; Kim, Hakseong; Cho, Yujin; Ryoo, Ji Hoon; Park, Cheol-Hwan; Kim, Pilkwang; Kim, Yong Seung; Lee, Sunwoo; Li, Yilei; Park, Seung-Nam; Shim Yoo, Yong; Yoon, Duhee; Dorgan, Vincent E.; Pop, Eric; Heinz, Tony F.; Hone, James; Chun, Seung-Hyun; Cheong, Hyeonsik; Lee, Sang Wook; Bae, Myung-Ho; Park, Yun Daniel

    2015-08-01

    Graphene and related two-dimensional materials are promising candidates for atomically thin, flexible and transparent optoelectronics. In particular, the strong light-matter interaction in graphene has allowed for the development of state-of-the-art photodetectors, optical modulators and plasmonic devices. In addition, electrically biased graphene on SiO2 substrates can be used as a low-efficiency emitter in the mid-infrared range. However, emission in the visible range has remained elusive. Here, we report the observation of bright visible light emission from electrically biased suspended graphene devices. In these devices, heat transport is greatly reduced. Hot electrons (˜2,800 K) therefore become spatially localized at the centre of the graphene layer, resulting in a 1,000-fold enhancement in thermal radiation efficiency. Moreover, strong optical interference between the suspended graphene and substrate can be used to tune the emission spectrum. We also demonstrate the scalability of this technique by realizing arrays of chemical-vapour-deposited graphene light emitters. These results pave the way towards the realization of commercially viable large-scale, atomically thin, flexible and transparent light emitters and displays with low operation voltage and graphene-based on-chip ultrafast optical communications.

  2. 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.

  3. 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

  4. Energy balance in a bright active prominence

    International Nuclear Information System (INIS)

    The transitions between ten levels and hydrogen atom continuum and 4S, 3D, 4P, Ca+ terms in a bright active prominence are considered. The role of electron impacts and solar radiation scattering taking account of optical thicknesses in all frequencies is considered. It has been found that hydrogen atoms and calcium ions radiate approximately equal amount of energy: 2.4x107 and 1.3x107 erg/cm2xs., respectively. The hydrogen atom radiation is by 2/3 due to solar radiation scattering, the contribution of the scattered radiation for various series and separate lines being unequal. The radiation in the n, k lines and in Ca+ infrared lines is almost completely ensured by electron impacts. Only the tenth part of the necessary energy is added on account of the solar radiation absorption. The total prominence radiation is half ensured due to solar radiation scattering. Approximately the same amount of energ is taken from the electron gas. The higher is q, the more significant becomes the role of electron impacts in hydrogen atom excitation and ionization. The q prominence duty factor value is near to unity

  5. 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.

  6. Magnetic flux supplement to coronal bright points

    CERN Document Server

    Mou, Chaozhou; Xia, Lidong; Madjarska, Maria S; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong

    2015-01-01

    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 analyse longitudinal magnetograms from the Helioseismic and Magnetic Imager to investigate the photospheric magnetic flux evolution of 70 BPs. From images taken in the 193 A passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs' lifetimes vary from 2.7 to 58.8 hours. 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 a MBF can involve more than one of these processes. Out of the 70 cases, flux emergence is the main process of a 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 \\AA\\ passband varie...

  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. 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.

  9. 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...

  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. 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.

  12. Osteoblastic differentiation and stress response of human mesenchymal stem cells exposed to alternating current electric fields

    Directory of Open Access Journals (Sweden)

    Kaplan David L

    2011-01-01

    Full Text Available Abstract Background Electric fields are integral to many biological events, from maintaining cellular homeostasis to embryonic development to healing. The application of electric fields offers substantial therapeutic potential, while optimal dosing regimens and the underlying mechanisms responsible for the positive clinical impact are poorly understood. Methods The purpose of this study was to track the differentiation profile and stress response of human bone marrow derived mesenchymal stem cells (hMSCs undergoing osteogenic differentiation during exposure to a 20 mV/cm, 60 kHz electric field. Morphological and biochemical changes were imaged using endogenous two-photon excited fluorescence (TPEF and quantitatively assessed through eccentricity calculations and extraction of the redox ratio from NADH, FAD and lipofuscin contributions. Real time reverse transcriptase-polymerase chain reactions (RT-PCR were used to track osteogenic differentiation markers, namely alkaline phosphatase (ALP and collagen type 1 (col1, and stress response markers, such as heat shock protein 27 (hsp27 and heat shock protein 70 (hsp70. Comparisons of collagen deposition between the stimulated hMSCs and controls were examined through second harmonic generation (SHG imaging. Results Quantitative differences in cell morphology, as described through an eccentricity ratio, were found on days 2 and days 5 (p Conclusions Electrical stimulation is a useful tool to improve hMSC osteogenic differentiation, while heat shock proteins may reveal underlying mechanisms, and optical non-invasive imaging may be used to monitor the induced morphological and biochemical changes.

  13. Immunotropic potency of microwave fields: preliminary studies on immunocompetent cells exposed in vitro

    International Nuclear Information System (INIS)

    Exposure in radiofrequency (RF) and microwave (MW) fields can influence the function of the immune system, but the data available on the immunotropic potency of RF/MW radiation are still full of uncertainties and controversies. In the available literature there exist no reports on complex assessment of function and responsiveness of the immune system. All investigations have been aimed to evaluate selected, fragmentary reaction of the system and/or functional response of immunocompetent cells in RF/MW-exposed subjects. However, at the present state of knowledge it is not possible to conclude about the possible immunotropic potencies of RF/MW radiation. The undisturbed defensive, tolerogenic, and proregenerative activities of the immune system are commonly recognised as one of the most important homeostatic functions of the organism. Thus, basic immunoregulatory activities which can be observed and precisely quantified in microcultures of immune cells separated from the human blood, represent a unique and objective model for the investigation of possible immunotropic effects of electromagnetic fields (EMFs). To determine the potential immunomodulatory influences of EMFs, the immunotropic effects of pulse modulated microwave (1300 MHz) were investigated in the cultures of blood mononuclear cells from sixteen healthy donors

  14. Intrinsic brightness temperatures of blazar jets at 15 GHz

    Directory of Open Access Journals (Sweden)

    Hovatta Talvikki

    2013-12-01

    Full Text Available We have developed a new Bayesian Markov Chain Monte Carlo method to deconvolve light curves of blazars into individual flares, including proper estimation of the fit errors. We use the method to fit 15GHzlight curves obtained within the OVRO 40-m blazar monitoring program where a large number of AGN have been monitored since 2008 in support of the Fermi Gamma-Ray Space Telescope mission. The time scales obtained from the fitted models are used to calculate the variability brightness temperature of the sources. Additionally, we have calculated brightness temperatures of a sample of these objects using Very Long Baseline Array data from the MOJAVE survey. Combining these two data sets enables us to study the intrinsic brightness temperature distribution in these blazars at 15 GHz. Our preliminary results indicate that the mean intrinsic brightness temperature in a sample of 14 sources is near the equipartition brightness temperature of ~ 1011K.

  15. 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...

  16. 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.

  17. 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...

  18. L Band Brightness Temperature Observations over a Corn Canopy during the Entire Growth Cycle

    OpenAIRE

    Alicia T. Joseph; Rogier van der Velde; O’Neill, Peggy E.; Choudhury, Bhaskar J.; Lang, Roger H.; Kim, Edward J.; Timothy Gish

    2010-01-01

    During a field campaign covering the 2002 corn growing season, a dual polarized tower mounted L-band (1.4 GHz) radiometer (LRAD) provided brightness temperature (TB) measurements at preset intervals, incidence and azimuth angles. These radiometer measurements were supported by an extensive characterization of land surface variables including soil moisture, soil temperature, vegetation biomass, and surface roughness. In the period May 22 to August 30, ten days of radiometer and ground measurem...

  19. Genotoxic effects of 50 Hz magnetic fields on human blood cells

    International Nuclear Information System (INIS)

    Full text: The possible health hazard of exposure to extremely low frequency magnetic fields (ELFMFs) has became an issue of considerable public concern. Although many epidemiological studies have been done, a definite correlation between exposure to environmental ELFMFs and cancer has not been found.. According to several investigations, ELF fields cannot directly damage DNA or cause mutations (NRPB,1992; Verschaeve 1995). On the other hand few studies have addressed the possibility that ELF magnetic fields could be able to enhance the genotoxic effect of known chemical or physical mutagens (Hintenlang, 1993; Maes et al., 2000). The aim of the present study is to investigate the potential genotoxic effect of ELFMFs alone or in combination with X rays on human blood cells. Four different cytogenetic tests (chromosome aberration, cytokinesis-block micronucleus, sister chromatid exchange and comet assay) have been applied. Human blood samples were exposed to 50 Hz, 1 mT uniform magnetic field generated by a Helmholtz coil system, in incubator. Whole blood samples from three healthy donors (30-40 years) were exposed to ELF MFs for 2 h and further blood samples from other three donors were diluted in culture medium in absence of phytoemoagglutinin and then exposed for 48 h to ELF fields. A sham control consisting on a same current system, with the coils activated in anti-parallel direction was used. A positive control (1 Gy of X-rays) were also included. A potential synergistic effect between ELF and X-rays (1 Gy) exposures was also investigated. Results did not show any significant differences between 2 h ELFMFs-exposed and unexposed samples for each cytogenetic endpoints analyzed. Similarly, the combined treatments failed to indicate the presence of any synergistic effect between the ELF magnetic fields and the physical mutagen. Results from the 48 h exposure time are currently being processed. (author)

  20. Non-uniform electric field-induced yeast cell electrokinetic behavior

    Directory of Open Access Journals (Sweden)

    Flavio Humberto Fernández Morales

    2010-05-01

    Full Text Available Common dielectrophoresis (c-DEP, i.e. neutral matter motion induced by non-uniform electric fields has become a basic pheno-menon of biochips intended for medical, biological and chemical assays, especially when they imply bioparticle handling. This paper deals with modelling and experimental verification of a castellated, c-DEP-based, microelectrode array intended to handle biological objects. The proposed microsystem was developed employing platinum electrodes patterned by lift-off, silicon micro-machining and photoresin patterning techniques. Saccharomyces cerevisiae were used as test bioparticles for experimental verifi-cation. Yeast cells were repelled toward electrode bays and toward interelectrodic gaps tor frequencies around 20 MHz where there is minimum electric field strength, corresponding to a negative dielectrophoretic phenomenon. Yeast cell agglomerations were observed around electrode edges for frequencies of around 2 MHz where there is maximum electric field strength, thereby verifying the positive dielectrophoretic phenomenon. Bioparticles were separated from the electrode edges when the working fre-quency was reduced and they were dragged towards the electrode centre, remaining there while the frequency was low enough. Such atypical pattern may be explained due to the occurrence of positive dielectrophoresis overlap with electrohydrodynamic effects (i.e. the viscous drag force acting on the particles was greater than the dielectrophoretic force at frequencies where positi-ve dielectrophoresis should occur. The experiments illustrated microsystem convenience in microhandling biological objects, the-reby providing these microarrays’ possible use with other cells. Liquid motion resulting from electrohydrodynamic effects must also be taken into account when designing bioparticle micromanipulators, and could be used as a mechanism for cleaning electrode surfaces.

  1. Action of 50 Hz magnetic fields on cyclic AMP and intercellular communication in monolayers and spheroids of mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Schimmelpfeng, J.; Stein, J.C.; Dertinger, H. [Research Center Karlsruhe (Germany). Inst. of Toxicology

    1995-12-31

    To investigate the influence of physiological parameters such as cell density and three-dimensional cell contact on the biological action of a 2mT/50 Hz magnetic field, mouse fibroblasts were exposed as monolayers and as multicellular spheroids. Changes in cyclic AMP content of cells and alterations in gap junction-mediated intercellular communication were measured immediately after 5 min of exposure to the field. In monolayers of intermediate cell density (1 {times} 10{sup 5} cells/cm{sup 2}), the field treatment caused an increase in cAMP to 121% of the control level, whereas, at 3 {times} 10{sup 5} cells/cm{sup 2} (near confluence), a decrease to 88% of the unexposed cells was observed. Furthermore, field exposure stimulated gap-junction communication to 160% of the control level as determined by Lucifer yellow dye exchange. In spheroids, alterations in the radial profile of cellular cAMP were observed that were due both to field-induced local cAMP changes and to increased gap-junction permeability for this second messenger, the latter causing radial cAMP gradients to be flattened. The results indicate a strong dependence of field action on physiological parameters of the system exposed.

  2. High-field-strength MR imaging evaluation of stroke in the sickle cell population

    International Nuclear Information System (INIS)

    Stroke is a well-known but understudied complication of sickle cell disease (SCD). The authors have studied the incidence and patterns of clinical and subclinical stroke in 73 SCD patients. The patients underwent formal neurologic evaluation and high-field strength, heavily T2-weighted axial cranial MR imaging (TR = 3,500 msec, TE = 80 msec). Eighteen of the 73 patients had clinical strokes, acute, nonconvulsive neurologic events with lateralizing neurological signs lasting 1 hour. All but two of these patients demonstrated focal MR imaging abnormalities. The remaining 55 patients were controls. Ten percent of them had focal MR imaging abnormalities suggesting subclinical stroke. A feature of the SCD population is the preponderance of strokes in the distal field and watershed distribution

  3. Electric cell voltage at etching and deposition of metals under an inhomogeneous constant magnetic field

    Directory of Open Access Journals (Sweden)

    O.Yu. Gorobets

    2014-12-01

    Full Text Available The self-organized electric cell voltage of the physical circuit is calculated at etching and deposition of metals at the surface of a magnetized ferromagnetic electrode in an electrolyte without passing an external electrical current. This self-organized voltage arises due to the inhomogeneous distribution of concentration of the effectively dia- or paramagnetic cluster components of an electrolyte at the surface of a ferromagnetic electrode under the effect of inhomogeneous magnetostatic fields. The current density and Lorentz force are calculated in an electrolyte in the vicinity of the magnetized steel ball-shaped electrode. The Lorentz force causes the rotation of an electrolyte around the direction of an external magnetic field.

  4. Effects of an electromagnetic field on intracellular calcium oscillations in a cell with external noise

    International Nuclear Information System (INIS)

    Intracellular calcium ion concentration oscillation in a cell subjected to external noise and irradiated by an electromagnetic field is considered. The effects of the intensity E0, the polar angle θ and the frequency ω of the external electric field on steady-state probability distribution and the mean Ca2+ concentration, respectively, are investigated by a numerical calculation method. The results indicate that (i) variation of ω cannot affect the intracellular calcium oscillation; (ii) the steady-state probability distribution presents a meaningful modification due to the variations of E0 and θ, while variation of θ does not affect the steady-state probability distribution under the condition of a small E0, and E0 cannot affect the steady-state probability distribution either when θ = π/2; (iii) the mean Ca2+ concentration increases as E0 increases when θ 0 increasing when θ = π/2, but it increases with θ increasing when E0 is small. (general)

  5. A Parallelized 3D Particle-In-Cell Method With Magnetostatic Field Solver And Its Applications

    Science.gov (United States)

    Hsu, Kuo-Hsien; Chen, Yen-Sen; Wu, Men-Zan Bill; Wu, Jong-Shinn

    2008-10-01

    A parallelized 3D self-consistent electrostatic particle-in-cell finite element (PIC-FEM) code using an unstructured tetrahedral mesh was developed. For simulating some applications with external permanent magnet set, the distribution of the magnetostatic field usually also need to be considered and determined accurately. In this paper, we will firstly present the development of a 3D magnetostatic field solver with an unstructured mesh for the flexibility of modeling objects with complex geometry. The vector Poisson equation for magnetostatic field is formulated using the Galerkin nodal finite element method and the resulting matrix is solved by parallel conjugate gradient method. A parallel adaptive mesh refinement module is coupled to this solver for better resolution. Completed solver is then verified by simulating a permanent magnet array with results comparable to previous experimental observations and simulations. By taking the advantage of the same unstructured grid format of this solver, the developed PIC-FEM code could directly and easily read the magnetostatic field for particle simulation. In the upcoming conference, magnetron is simulated and presented for demonstrating the capability of this code.

  6. Collisionless Reconnection in the Large Guide Field Regime: Gyrokinetic Versus Particle-in-Cell Simulations

    CERN Document Server

    TenBarge, J M; Karimabadi, H; Howes, G G; Dorland, W

    2013-01-01

    Results of the first validation of large guide field, $B_g / \\delta B_0 \\gg 1$, gyrokinetic simulations of magnetic reconnection at a fusion and solar corona relevant $\\beta_i = 0.01$ and solar wind relevant $\\beta_i = 1$ are presented, where $\\delta B_0$ is the reconnecting field. Particle-in-cell (PIC) simulations scan a wide range of guide magnetic field strength to test for convergence to the gyrokinetic limit. The gyrokinetic simulations display a high degree of morphological symmetry, to which the PIC simulations converge when $\\beta_i B_g / \\delta B_0 \\gtrsim 1$ and $B_g / \\delta B_0 \\gg 1$. In the regime of convergence, the reconnection rate, relative energy conversion, and overall magnitudes are found to match well between the PIC and gyrokinetic simulations, implying that gyrokinetics is capable of making accurate predictions well outside its regime of formal applicability. These results imply that in the large guide field limit many quantities resulting from the nonlinear evolution of reconnection ...

  7. 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

  8. Stray magnetic field influence on the CPT resonance in a coated Rb vacuum cell

    Science.gov (United States)

    Taskova, E.; Alipieva, E.; Todorov, G.

    2016-03-01

    Interaction of a resonant laser beam with an atomic absorption medium creates population redistribution and interference between atomic levels. This anisotropy of the medium is experimentally observed as coherent population trapping (CPT) or electromagnetically induced transparency (EIT). Due to the small sub-natural width of the CPT and EIT resonances, they find wide applications in metrology, quantum optics, atom cooling. A non-compensated stray magnetic field (SMF) can change the shape and sign of the resonance or destroy it completely. In this work, we present an experimental and theoretical investigation of the influence of a stray magnetic field on the CPT resonances obtained on Zeeman sublevels of the D1 line of 87Rb in a paraffin-coated vacuum cell. The role is clarified of the polarization moments with different rank in creating the integral registered fluorescent signal in the presence of a stray magnetic field. It is shown that a transverse magnetic field plays an important role in changing the shape of the signal.

  9. 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 ...

  10. 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)

  11. 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...

  12. Photometry of Very Bright Stars with Kepler and K2 Smear Data

    CERN Document Server

    Pope, Benjamin; Huber, Daniel; Murphy, Simon; Bedding, Tim; Caldwell, Douglas; Sarai, Aleksa; Aigrain, Suzanne; Barclay, Thomas

    2015-01-01

    High-precision time series photometry with the Kepler satellite has been crucial to our understanding both of exoplanets, and via asteroseismology, of stellar physics. After the failure of two reaction wheels, the Kepler satellite has been repurposed as Kepler-2 (K2), observing fields close to the ecliptic plane. As these fields contain many more bright stars than the original Kepler field, K2 provides an unprecedented opportunity to study nearby objects amenable to detailed follow-up with ground-based instruments. Due to bandwidth constraints, only a small fraction of pixels can be downloaded, with the result that most bright stars which saturate the detector are not observed. We show that engineering data acquired for photometric calibration, consisting of collateral `smear' measurements, can be used to reconstruct light curves for bright targets not otherwise observable with Kepler/K2. Here we present some examples from Kepler Quarter 6 and K2 Campaign 3, including the delta Scuti variables HD 178875 and 7...

  13. 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...

  14. Single-Cell Quantification of Cytosine Modifications by Hyperspectral Dark-Field Imaging.

    Science.gov (United States)

    Wang, Xiaolei; Cui, Yi; Irudayaraj, Joseph

    2015-12-22

    Epigenetic modifications on DNA, especially on cytosine, play a critical role in regulating gene expression and genome stability. It is known that the levels of different cytosine derivatives are highly dynamic and are regulated by a variety of factors that act on the chromatin. Here we report an optical methodology based on hyperspectral dark-field imaging (HSDFI) using plasmonic nanoprobes to quantify the recently identified cytosine modifications on DNA in single cells. Gold (Au) and silver (Ag) nanoparticles (NPs) functionalized with specific antibodies were used as contrast-generating agents due to their strong local surface plasmon resonance (LSPR) properties. With this powerful platform we have revealed the spatial distribution and quantity of 5-carboxylcytosine (5caC) at the different stages in cell cycle and demonstrated that 5caC was a stably inherited epigenetic mark. We have also shown that the regional density of 5caC on a single chromosome can be mapped due to the spectral sensitivity of the nanoprobes in relation to the interparticle distance. Notably, HSDFI enables an efficient removal of the scattering noises from nonspecifically aggregated nanoprobes, to improve accuracy in the quantification of different cytosine modifications in single cells. Further, by separating the LSPR fingerprints of AuNPs and AgNPs, multiplex detection of two cytosine modifications was also performed. Our results demonstrate HSDFI as a versatile platform for spatial and spectroscopic characterization of plasmonic nanoprobe-labeled nuclear targets at the single-cell level for quantitative epigenetic screening. PMID:26505210

  15. Dark Skies, Bright Kids: Year 2

    Science.gov (United States)

    Carlberg, Joleen K.; Johnson, K.; Lynch, R.; Walker, L.; Beaton, R.; Corby, J.; de Messieres, G.; Drosback, M.; Gugliucci, N.; Jackson, L.; Kingery, A.; Layman, S.; Murphy, E.; Richardson, W.; Ries, P.; Romero, C.; Sivakoff, G.; Sokal, K.; Trammell, G.; Whelan, D.; Yang, A.; Zasowski, G.

    2011-01-01

    The Dark Skies, Bright Kids (DSBK) outreach program brings astronomy education into local elementary schools in central Virginia's Southern Albemarle County through an after-school club. Taking advantage of the unusually dark night skies in the rural countryside, DSBK targets economically disadvantaged schools that tend to be underserved due to their rural locale. The goals of DSBK are to foster children's natural curiosity, demonstrate that science is a fun and creative process, challenge students' conceptions of what a scientist is and does, and teach some basic astronomy. Furthermore, DSBK works to assimilate families into students' education by holding family observing nights at the school. Now in its third semester, DSBK has successfully run programs at two schools with very diverse student populations. Working with these students has helped us to revise our activities and to create new ones. A by-product of our work has been the development of lesson plans, complete with learning goals and detailed instructions, that we make publically available on our website. This year we are expanding our repertoire with our new planetarium, which allows us to visualize topics in novel ways and supplements family observing on cloudy nights. The DSBK volunteers have also created a bilingual astronomy artbook --- designed, written, and illustrated by UVa students --- that we will publish and distribute to elementary schools in Virginia. Our book debuted at the last AAS winter meeting, and since then it has been extensively revised and updated with input from many individuals, including parents, professional educators, and a children's book author. Because the club is currently limited to serving a few elementary schools, this book will be part of our efforts to broaden our impact by bringing astronomy to schools we cannot go to ourselves and reaching out to Spanish-speaking communities at the same time.

  16. 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.

  17. 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.

  18. Strong synergy of heat and modulated electromagnetic field in tumor cell killing

    International Nuclear Information System (INIS)

    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.)

  19. 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.)

  20. 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.

  1. 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

  2. Effects of Static Magnetic Field on Growth of Leptospire, Leptospira interrogans serovar canicola: Immunoreactivity and Cell Division

    OpenAIRE

    Triampo, Wannapong; Doungchawee, Galayanee; Triampo, Darapond; Wong-Ekkabut, Jirasak; Tang, I-Ming

    2004-01-01

    The effects of the exposure of the bacterium, Leptospira interrogans serovar canicola to a constant magnetic field with magnetic flux density from a permanent ferrite magnet = 140 mT were studied. Changes in Leptospira cells after their exposure to the field were determined on the basis of changes in their growth behavior and agglutination immunoreactivity with a homologous antiserum using darkfield microscopy together with visual imaging. The data showed that the exposed Leptospira cells hav...

  3. Electric Equivalent Models of Intrinsic Recombination Velocities of a Bifacial Silicon Solar Cell under Frequency Modulation and Magnetic Field Effect

    OpenAIRE

    Nd. Thiam; A. Diao; NDiaye, M; Dieng, A.; Thiam, A.; Sarr, M.; A.S. Maiga; G. Sissoko

    2012-01-01

    In this study, we present a theoretical study of the photogenerated charge carriers in the base of an illuminated n+-p-p+ crystalline silicon solar cell under an external magnetic field. By solving the charge carriers’ continuity equation, the dependence of diffusion coefficient and the photocurrent density on the frequency modulation and magnetic field, is studied. Hence, the study of intrinsic recombination velocities at the junction Sfo1 and rear side Sbo1 of the solar cell, leads to elect...

  4. 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

  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. A universal threshold for the formation of bright galaxies

    CERN Document Server

    Zhao, HongSheng; Dobbs, Clare

    2008-01-01

    The tight correlation between galaxy bulges and their central black hole masses likely emerges in a phase of rapid collapse and starburst at high redshift. The correlation is due to the balance of gravity on gas with the feedback force from starbursts and the wind from the black hole. The tightness suggests a universal scale of gravity on gas during this phase. The scalar field in some co-variant versions of MOND can create the mirage of a Newtonian effective dark halo with a "dark" gravity being a nearly universal value ~ (1.2/alpha)* 10^{-10} m sec^-2 for bright galaxies, where alpha ~ 1-3 is a fundamental constant in the Lagrangian of the theory. A dark gravity of similar order of magnitude which is insensitive to redshift can also be generated by the real 1/r cusps of Cold Dark Matter (CDM) halos. However the values generally have a larger scatter, which increases with the mass of the galaxies and adiabatic contraction effects of gas collapse. We show with a toy analytical model and a hydrodynamical simul...

  7. 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...

  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. 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...

  10. 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

  11. 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...

  12. Clarinet laser: Semiconductor laser design for high-brightness applications

    Science.gov (United States)

    Borruel, Luis; Esquivias, Ignacio; Moreno, Pablo; Krakowski, Michel; Auzanneau, Sophie Charlotte; Calligaro, Michel; Parillaud, Olivier; Lecomte, Michel; Sujecki, Slawomir; Wykes, Jim; Larkins, Eric C.

    2005-09-01

    High-power and high-brightness continuous-wave (cw) operation has been achieved with an optimized design of fully index-guided tapered laser emitting at 975 nm. The device achieves simultaneously negligible astigmatism and stable low divergence in the lateral axis at high-power operation. By using a quasi-three-dimensional simulation model, the different mechanisms modifying the slow axis beam divergence at high power have been carefully balanced in the clarinet design, easing the use of collective optics in laser bars. The devices consist of a relatively long ridge-waveguide filtering section coupled to a relatively short tapered section with an aperture angle of 2°. InGaAs /InGaAsP lasers were fabricated with this design, demonstrating an output power of 1 W cw, a maximum wall-plug efficiency of 50%, negligible astigmatism, a slow-axis far-field divergence (measured at 1/e2) of 5° at 1 W and beam quality parameter M2<3.

  13. 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.

  14. 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.

  15. 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)

  16. Lamp spectrum and spatial brightness at photopic levels

    DEFF Research Database (Denmark)

    Fotios, Steve; Atli, Deniz; Cheal, Chris; Houser, Kevin; Logadóttir, Ásta

    2015-01-01

    lower illuminance with potential reductions in energy consumption. Consideration of experimental design was used to review 70 studies of spatial brightness. Of these, the 19 studies considered to provide credible evidence of SPD effects were used to explore metrics for predicting the effect of SPD but......Light sources are available in a variety of spectral power distributions (SPDs) and this affects spatial brightness in a manner not predicted by quantities such as illuminance. Tuning light source SPD to better match the sensitivity of visual perception may allow the same spatial brightness but at...

  17. First magnitude a book of the bright sky

    CERN Document Server

    Kaler, James B

    2012-01-01

    "First Magnitude" is an entry-level book for readers with brightly lit skies. Its purpose is to show them that all is not lost, that they can still enjoy personal astronomy and have an appreciation of the heavens no matter where they live. It concentrates on the Sun, Moon, the five bright planets, and on the 23 brightest stars, which are visible from just about anywhere. The book concludes with bright ephemeral phenomena: meteors, comets, and exploding stars. The concept is a platform for introducing the reader to the wonders of the nighttime and daytime skies and serves as an introduction to

  18. Electric currents and fields induced in cells in the human brain by radiation from hand-held cellular telephones

    Science.gov (United States)

    King, Ronold W. P.

    2000-01-01

    After a review of recent work on the interaction of electromagnetic fields from cellular telephones with the human head, the structural and radiating properties of two common types of transceivers are determined. These include the impedance and current amplitude distribution of the antennas. The tangential electric field maintained by the antennas on the adjacent surface of the head is next determined. From this, the electric field propagating through the skull into the brain is analyzed and, from it, the electric field in spherical and long cylindrical cells is determined. It ranges from 27 to 13.5 V/m in the first 3 cm inside the skull. Of interest is the fact that the induced field in the interior of all cells, regardless of their shape, is the same as the incident field in the brain. It is hoped that biomedical scientists will review these results and determine possible biological effects.

  19. Comparison between pulsed-field and constant-field gel electrophoresis for measurement of DNA double-strand breaks in irradiated Chinese hamster ovary cells

    International Nuclear Information System (INIS)

    Pulsed-field gel electrophoresis (PFGE) is one of the most sensitive methods for detecting DNA double-strand breaks in mammalian cells. However, it has been observed that constant-field gel electrophoresis (CFGE), when optimized, can detect breaks with equal efficiency. The migration of DNA from the well and the separation of DNA molecules according to size appear to be different processes; only the latter requires the application of PFGE. CFGE is very sensitive and can detect DNA damage produced by less than 5Gy of radiation. Low voltage (ca.0.6V/cm) during electrophoresis appears to be essential for the migration of the largest fraction of DNA from the agarose plug containing the cells; the electrophoresis run time, cell density in the plug, agarose concentration, nature of detergent and extent of radiolabelling are less important. It is concluded that CFGE is equally sensitive but more rapid and economical than PFGE for the measurement of DNA damage. (author)

  20. Investigation of superparamagnetic (Fe3O4) nanoparticles and magnetic field exposures on CHO-K1 cell line

    Science.gov (United States)

    Coker, Zachary; Estlack, Larry; Hussain, Saber; Choi, Tae-Youl; Ibey, Bennett L.

    2016-03-01

    Rapid development in nanomaterial synthesis and functionalization has led to advanced studies in actuation and manipulation of cellular functions for biomedical applications. Often these actuation techniques employ externally applied magnetic fields to manipulate magnetic nanomaterials inside cell bodies in order to drive or trigger desired effects. While cellular interactions with low-frequency magnetic fields and nanoparticles have been extensively studied, the fundamental mechanisms behind these interactions remain poorly understood. Additionally, modern investigations on these concurrent exposure conditions have been limited in scope, and difficult to reproduce. This study presents an easily reproducible method of investigating the biological impact of concurrent magnetic field and nanoparticle exposure conditions using an in-vitro CHO-K1 cell line model, with the purpose of establishing grounds for in-depth fundamental studies of the mechanisms driving cellular-level interactions. Cells were cultured under various nanoparticle and magnetic field exposure conditions from 0 to 500 μg/ml nanoparticle concentrations, and DC, 50 Hz, or 100 Hz magnetic fields with 2.0 mT flux density. Cells were then observed by confocal fluorescence microscopy, and subject to biological assays to determine the effects of concurrent extreme-low frequency magnetic field and nanoparticle exposures on cellnanoparticle interactions, such as particle uptake and cell viability by MTT assay. Current results indicate little to no variation in effect on cell cultures based on magnetic field parameters alone; however, it is clear that deleterious synergistic effects of concurrent exposure conditions exist based on a significant decrease in cell viability when exposed to high concentrations of nanoparticles and concurrent magnetic field.