WorldWideScience

Sample records for space molecule detection

  1. Carbon Nanotube Biosensors for Space Molecule Detection and Clinical Molecular Diagnostics

    Science.gov (United States)

    Han, Jie

    2001-01-01

    Both space molecule detection and clinical molecule diagnostics need to develop ultra sensitive biosensors for detection of less than attomole molecules such as amino acids for DNA. However all the electrode sensor systems including those fabricated from the existing carbon nanotubes, have a background level of nA (nanoAmp). This has limited DNA or other molecule detection to nA level or molecules whose concentration is, much higher than attomole level. A program has been created by NASA and NCI (National Cancer Institute) to exploit the possibility of carbon nanotube based biosensors to solve this problem for both's interest. In this talk, I will present our effort on the evaluation and novel design of carbon nanotubes as electrode biosensors with strategies to minimize background currents while maximizing signal intensity.The fabrication of nanotube electrode arrays, immobilization of molecular probes on nanotube electrodes and in vitro biosensor testing will also be discussed.

  2. Space Detectives

    Science.gov (United States)

    Tyszka, Steph; Saraiva, Jose; Doran, Rosa

    2017-04-01

    NUCLIO is a Portuguese non-profit organization with a strong record of investing in science education and outreach. We have developed and implemented many activities mostly directed to a young audience, in a bid to awaken and reinforce the interest that young people devote to Astronomy and all things spatial. In this framework, we have created a week-long program called Space Detectives, supported by the Municipality of Cascais, based on a story-line that provided a number of challenges and opportunities for learning matters as diverse as the electro-magnetic spectrum, means of communication, space travel, the martian environment, coding and robotics. We report on the first session that took place in December 2016. We had as participants several kids aged 9 to 12, with a mixed background in terms of interest in the sciences. Their response varied from enthusiastic to somewhat less interested, depending on the nature of the subject and the way it was presented - a reaction not necessarily related to its complexity. This week was taken as something of a trial run, in preparation for the European Commission- funded project "Stories of Tomorrow", to be implemented in schools. The individual activities and the way they were related to the story-line, as well as the smooth transition from one to the next, were subject to an analysis that will allow for improvements in the next installments of this program. We believe this is an excellent approach to the goals of using Space and Astronomy as an anchor for generating and keeping interest in the scientific areas, and of finding new and richer ways of learning.

  3. Single-molecule manipulation and detection.

    Science.gov (United States)

    Zhao, Deyu; Liu, Siyun; Gao, Ying

    2018-01-25

    Compared to conventional ensemble methods, studying macromolecules at single-molecule level can reveal extraordinary clear and even surprising views for a biological reaction. In the past 20 years, single-molecule techniques have been undergoing a very rapid development, and these cutting edge technologies have revolutionized the biological research by facilitating single-molecule manipulation and detection. Here we give a brief review about these advanced techniques, including optical tweezers, magnetic tweezers, atomic force microscopy (AFM), hydrodynamic flow-stretching assay, and single-molecule fluorescence resonance energy transfer (smFRET). We are trying to describe their basic principles and provide a few examples of applications for each technique. This review aims to give a rather introductory survey of single-molecule techniques for audiences with biological or biophysical background. © The Author(s) 2018. Published by Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Momentum-space calculation of electron-molecule scattering

    International Nuclear Information System (INIS)

    McCarthy, I.E.; Rossi, A.M.

    1994-01-01

    The momentum-space calculation of electron-molecule elastic scattering is described and illustrated as the first step in a program of electron-molecule scattering that takes all reaction channels into account. The method is the analog for molecules of the integral-equation methods that have had essentially complete success for structurally simple atoms. Although scattering is a single-center problem in momentum space its multicentered nature in coordinate space results in the integral equations for different orbital angular momenta being coupled. There are no restrictions in principle on the nature of the target molecule. For illustrative purposes the static exchange calculation is supplemented by a phenomenological polarization potential that will be replaced by an ab initio optical potential and coupled electronic channels in the planned development of a general scattering method

  5. Single Molecule 3D Orientation in Time and Space

    NARCIS (Netherlands)

    Börner, Richard; Ehrlich, Nicky; Hohlbein, Johannes; Hübner, Christian G.

    2016-01-01

    Interactions between single molecules profoundly depend on their mutual three-dimensional orientation. Recently, we demonstrated a technique that allows for orientation determination of single dipole emitters using a polarization-resolved distribution of fluorescence into several detection

  6. Evolution of organic molecules under Mars-like UV radiation conditions in space and laboratory

    Science.gov (United States)

    Rouquette, L.; Stalport, F.; Cottin, H.; Coll, P.; Szopa, C.; Saiagh, K.; Poch, O.; Khalaf, D.; Chaput, D.; Grira, K.; Dequaire, T.

    2017-09-01

    The detection and identification of organic molecules at Mars are of prime importance, as some of these molecules are life precursors and components. While in situ planetary missions are searching for them, it is essential to understand how organic molecules evolve and are preserved at the surface of Mars. Indeed the harsh conditions of the environment of Mars such as ultraviolet (UV) radiation or oxidative processes could explain the low abundance and diversity of organic molecules detected by now [1]. In order to get a better understanding of the evolution of organic matter at the surface of Mars, we exposed organic molecules under a Mars-like UV radiation environment. Similar organic samples were exposed to the Sun radiation, outside the International Space Station (ISS), and under a UV lamp (martian pressure and temperature conditions) in the laboratory. In both experiments, organic molecules tend to photodegrade under Mars-like UV radiation. Minerals, depending on their nature, can protect or accelerate the degradation of organic molecules. For some molecules, new products, possibly photoresistant, seem to be produced. Finally, experimenting in space allow us to get close to in situ conditions and to validate our laboratory experiment while the laboratory experiment is essential to study the evolution of a large amount and diversity of organic molecules.

  7. Isolation and detection of small RNA molecules

    Czech Academy of Sciences Publication Activity Database

    Fulneček, Jaroslav

    2007-01-01

    Roč. 53, - (2007), s. 451-455 ISSN 1214-1178 R&D Projects: GA ČR(CZ) GA204/06/1432 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : small RNA molecules * electrophoresis Subject RIV: BO - Biophysics

  8. Detecting high-density ultracold molecules using atom–molecule collision

    International Nuclear Information System (INIS)

    Chen, Jun-Ren; Kao, Cheng-Yang; Chen, Hung-Bin; Liu, Yi-Wei

    2013-01-01

    Utilizing single-photon photoassociation, we have achieved ultracold rubidium molecules with a high number density that provides a new efficient approach toward molecular quantum degeneracy. A new detection mechanism for ultracold molecules utilizing inelastic atom–molecule collision is demonstrated. The resonant coupling effect on the formation of the X 1 Σ + g ground state 85 Rb 2 allows for a sufficient number of more deeply bound ultracold molecules, which induced an additional trap loss and heating of the co-existing atoms owing to the inelastic atom–molecule collision. Therefore, after the photoassociation process, the ultracold molecules can be investigated using the absorption image of the ultracold rubidium atoms mixed with the molecules in a crossed optical dipole trap. The existence of the ultracold molecules was then verified, and the amount of accumulated molecules was measured. This method detects the final produced ultracold molecules, and hence is distinct from the conventional trap loss experiment, which is used to study the association resonance. It is composed of measurements of the time evolution of an atomic cloud and a decay model, by which the number density of the ultracold 85 Rb 2 molecules in the optical trap was estimated to be >5.2 × 10 11 cm −3 . (paper)

  9. Molecules from Space and the Origin of Life

    Science.gov (United States)

    Bernstein Max P.; Sandford, Scott A.; Allamandola, Louis J.; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    There is a growing concensus among space scientists that frozen molecules from space helped to make the Earth the pleasant place that it is today, and helped Life start on Earth, and perhaps elsewhere. The chain of logic that led scientists to posit a connection between extraterrestrial molecules and the origin of life is as follows. 1) The rapidity with which life arose demands that conditions on Earth were conducive to the formation of life very early on. 2) There is reason to believe that comets and meteorites fell oil the Earth from its inception. 3) We now know that comets and meteorites are replete with complex organic compounds, some of which resemble those in living systems. 4) Perhaps the input of molecules from comets and meteorites provided crucial constituents to the primordial soup and Jump started life on Earth. 5) These molecules formed out in deep space long before the Earth ever existed, by processes that we can reproduce in the laboratory. 6) The fact that organic molecules are seen by astronomers throughout our galaxy and in others makes it seem likely that they were (and are) available to help start life in other planetary systems.

  10. Single Molecule Raman Detection of Enkephalin on Silver Colloidal Particles

    DEFF Research Database (Denmark)

    Kneipp, Katrin; Kneipp, Holger; Abdali, Salim

    2004-01-01

    the Raman signal the enkephalin molecules have been attached to silver colloidal cluster structures. The experiments demonstrate that the SERS signal of the strongly enhanced ring breathing vibration of phenylalanine at 1000 cm-1 can be used as “intrinsic marker” for detecting a single enkephalin molecule...... and for monitoring its diffusion on the surface of the silver colloidal cluster without using a specific label molecule....

  11. Novel approaches for single molecule activation and detection

    CERN Document Server

    Benfenati, Fabio; Torre, Vincent

    2014-01-01

    How can we obtain tools able to process and exchange information at the molecular scale In order to do this, it is necessary to activate and detect single molecules under controlled conditions. This book focuses on the generation of biologically-inspired molecular devices. These devices are based on the developments of new photonic tools able to activate and stimulate single molecule machines. Additionally, new light sensitive molecules can be selectively activated by photonic tools. These technological innovations will provide a way to control activation of single light-sensitive molecules, a

  12. Single Molecule Raman Detection of Enkephalin on Silver Colloidal Particles

    DEFF Research Database (Denmark)

    Kneipp, Katrin; Kneipp, Holger; Abdali, Salim

    2004-01-01

    Enkephalin, an endogeneous substance in the human brain showing morphine-like biological functions, has been detected at the single molecule level based on the surface-enhanced Raman signal of the ring breathing mode of phenylalanine, which is one building block of the molecule. For enhancing...... the Raman signal the enkephalin molecules have been attached to silver colloidal cluster structures. The experiments demonstrate that the SERS signal of the strongly enhanced ring breathing vibration of phenylalanine at 1000 cm-1 can be used as “intrinsic marker” for detecting a single enkephalin molecule...... and for monitoring its diffusion on the surface of the silver colloidal cluster without using a specific label molecule....

  13. Detecting and identifying small molecules in a nanopore flux capacitor.

    Science.gov (United States)

    Bearden, Samuel; McClure, Ethan; Zhang, Guigen

    2016-02-19

    A new method of molecular detection in a metallic-semiconductor nanopore was developed and evaluated with experimental and computational methods. Measurements were made of the charging potential of the electrical double layer (EDL) capacitance as charge-carrying small molecules translocated the nanopore. Signals in the charging potential were found to be correlated to the physical properties of analyte molecules. From the measured signals, we were able to distinguish molecules with different valence charge or similar valence charge but different size. The relative magnitude of the signals from different analytes was consistent over a wide range of experimental conditions, suggesting that the detected signals are likely due to single molecules. Computational modeling of the nanopore system indicated that the double layer potential signal may be described in terms of disruption of the EDL structure due to the size and charge of the analyte molecule, in agreement with Huckel and Debye's analysis of the electrical atmosphere of electrolyte solutions.

  14. Astronomers Discover First Negatively-charged Molecule in Space

    Science.gov (United States)

    2006-12-01

    Cambridge, MA - Astronomers have discovered the first negatively charged molecule in space, identifying it from radio signals that were a mystery until now. While about 130 neutral and 14 positively charged molecules are known to exist in interstellar space, this is the first negative molecule, or anion, to be found. "We've spotted a rare and exotic species, like the white tiger of space," said astronomer Michael McCarthy of the Harvard-Smithsonian Center for Astrophysics (CfA). By learning more about the rich broth of chemicals found in interstellar space, astronomers hope to explain how the young Earth converted these basic ingredients into the essential chemicals for life. This new finding helps to advance scientists' understanding of the chemistry of the interstellar medium, and hence the birthplaces of planets. McCarthy worked with CfA colleagues Carl Gottlieb, Harshal Gupta (also from the Univ. of Texas), and Patrick Thaddeus to identify the molecular anion known as C6H-: a linear chain of six carbon atoms with one hydrogen atom at the end and an "extra" electron. Such molecules were thought to be extremely rare because ultraviolet light that suffuses space easily knocks electrons off molecules. The large size of C6H-, larger than most neutral and all positive molecules known in space, may increase its stability in the harsh cosmic environment. "The discovery of C6H- resolves a long-standing enigma in astrochemistry: the apparent lack of negatively charged molecules in space," stated Thaddeus. The team first conducted laboratory experiments to determine exactly what radio frequencies to use in their search. Then, they used the National Science Foundation's Robert C. Byrd Green Bank Telescope to hunt for C6H- in celestial objects. In particular, they targeted locations in which previous searches had spotted unidentified radio signals at the appropriate frequencies. They found C6H- in two very different locations-a shell of gas surrounding the evolved red giant

  15. Detection of quorum sensing molecules from Vibrio harveyi and use ...

    African Journals Online (AJOL)

    This paper explores the extraction and detection processes of quorum sensing molecules such as N-aceyl homoserine lactone compounds (AHL) from marine Vibrio harveyi. The spent culture of V. harveyi was solvent partitioned for AHL, rotary evaporated and re-suspended in 50% acetonitrile then detected with reporter ...

  16. Single molecule DNA detection with an atomic vapor notch filter

    Energy Technology Data Exchange (ETDEWEB)

    Uhland, Denis; Rendler, Torsten; Widmann, Matthias; Lee, Sang-Yun [University of Stuttgart and Stuttgart Research Center of Photonic Engineering (SCoPE) and IQST, 3rd Physics Institute, Stuttgart (Germany); Wrachtrup, Joerg; Gerhardt, Ilja [University of Stuttgart and Stuttgart Research Center of Photonic Engineering (SCoPE) and IQST, 3rd Physics Institute, Stuttgart (Germany); Max Planck Institute for Solid State Research, Stuttgart (Germany)

    2015-12-01

    The detection of single molecules has facilitated many advances in life- and material-science. Commonly the fluorescence of dye molecules is detected, which are attached to a non-fluorescent structure under study. For fluorescence microscopy one desires to maximize the detection efficiency together with an efficient suppression of undesired laser leakage. Here we present the use of the narrow-band filtering properties of hot atomic sodium vapor to selectively filter the excitation light from the red-shifted fluorescence of dye labeled single-stranded DNA molecules. A statistical analysis proves an enhancement in detection efficiency of more than 15% in a confocal and in a wide-field configuration. (orig.)

  17. Biological Nanopores: Confined Spaces for Electrochemical Single-Molecule Analysis.

    Science.gov (United States)

    Cao, Chan; Long, Yi-Tao

    2018-02-20

    Nanopore sensing is developing into a powerful single-molecule approach to investigate the features of biomolecules that are not accessible by studying ensemble systems. When a target molecule is transported through a nanopore, the ions occupying the pore are excluded, resulting in an electrical signal from the intermittent ionic blockade event. By statistical analysis of the amplitudes, duration, frequencies, and shapes of the blockade events, many properties of the target molecule can be obtained in real time at the single-molecule level, including its size, conformation, structure, charge, geometry, and interactions with other molecules. With the development of the use of α-hemolysin to characterize individual polynucleotides, nanopore technology has attracted a wide range of research interest in the fields of biology, physics, chemistry, and nanoscience. As a powerful single-molecule analytical method, nanopore technology has been applied for the detection of various biomolecules, including oligonucleotides, peptides, oligosaccharides, organic molecules, and disease-related proteins. In this Account, we highlight recent developments of biological nanopores in DNA-based sensing and in studying the conformational structures of DNA and RNA. Furthermore, we introduce the application of biological nanopores to investigate the conformations of peptides affected by charge, length, and dipole moment and to study disease-related proteins' structures and aggregation transitions influenced by an inhibitor, a promoter, or an applied voltage. To improve the sensing ability of biological nanopores and further extend their application to a wider range of molecular sensing, we focus on exploring novel biological nanopores, such as aerolysin and Stable Protein 1. Aerolysin exhibits an especially high sensitivity for the detection of single oligonucleotides both in current separation and duration. Finally, to facilitate the use of nanopore measurements and statistical analysis

  18. Rationale for single molecule detection by means of Raman spectroscopy

    International Nuclear Information System (INIS)

    Gaponenko, S.V.; Guzatov, D.V.

    2009-01-01

    A consistent quantum electrodynamical description is proposed of Raman scattering of light by a molecule in a medium with a modified photon density of states. Enhanced local density of states near a metal nanobody is shown to increase a scattering rate by several orders of magnitude, thus providing a rationale for experimental detection of single molecules by means of Raman spectroscopy. For an ellipsoidal particle 10 14 -fold enhancement of the Raman scattering cross-section is obtained. (authors)

  19. Single-molecule imaging towards precise detection of individual photophysics

    International Nuclear Information System (INIS)

    Tani, Toshiro; Oda, Masaru; Mashimo, Kei; Tachibana, Fumi; Horiuchi, Hiromi

    2006-01-01

    We present our recent study of single fluorescent molecules with specific structure, i.e. tetramethylrhodamine derivative linked with a propyl chain onto silica glass surface. For fluorescent reagent in its synthesis, we used a mixture of two kinds of isomers, which provides a sample with single molecules photophysically different each other even if chemically the same. The isomeric structural difference so introduced in the molecules will provide rather small but probably distinctive photophysical difference, for example, in non-radiative relaxation rates, which we try to detect out with our improved single-molecule microscope imaging technique. To make clear the detectability of such weak inter- or intra-molecular interactions microscopically is significant for versatile applications of single-molecule detections in life science. Our present observation at room temperatures shows so far that such decoupled contributions can be discriminated in the histograms of the intensities of the observed fluorescent spots as broader but separated multi-component structures in the distribution under specific experimental configurations. We will discuss some of the prerequisite for such detections; suitable spatio-temporal resolutions with sufficient S/N ratio, algorithms for data analysis, etc. but also precise sample operations are inevitable

  20. Direct single-molecule dynamic detection of chemical reactions.

    Science.gov (United States)

    Guan, Jianxin; Jia, Chuancheng; Li, Yanwei; Liu, Zitong; Wang, Jinying; Yang, Zhongyue; Gu, Chunhui; Su, Dingkai; Houk, Kendall N; Zhang, Deqing; Guo, Xuefeng

    2018-02-01

    Single-molecule detection can reveal time trajectories and reaction pathways of individual intermediates/transition states in chemical reactions and biological processes, which is of fundamental importance to elucidate their intrinsic mechanisms. We present a reliable, label-free single-molecule approach that allows us to directly explore the dynamic process of basic chemical reactions at the single-event level by using stable graphene-molecule single-molecule junctions. These junctions are constructed by covalently connecting a single molecule with a 9-fluorenone center to nanogapped graphene electrodes. For the first time, real-time single-molecule electrical measurements unambiguously show reproducible large-amplitude two-level fluctuations that are highly dependent on solvent environments in a nucleophilic addition reaction of hydroxylamine to a carbonyl group. Both theoretical simulations and ensemble experiments prove that this observation originates from the reversible transition between the reactant and a new intermediate state within a time scale of a few microseconds. These investigations open up a new route that is able to be immediately applied to probe fast single-molecule physics or biophysics with high time resolution, making an important contribution to broad fields beyond reaction chemistry.

  1. Single molecule transistor based nanopore for the detection of nicotine

    Science.gov (United States)

    Ray, S. J.

    2014-12-01

    A nanopore based detection methodology was proposed and investigated for the detection of Nicotine. This technique uses a Single Molecular Transistor working as a nanopore operational in the Coulomb Blockade regime. When the Nicotine molecule is pulled through the nanopore area surrounded by the Source(S), Drain (D), and Gate electrodes, the charge stability diagram can detect the presence of the molecule and is unique for a specific molecular structure. Due to the weak coupling between the different electrodes which is set by the nanopore size, the molecular energy states stay almost unaffected by the electrostatic environment that can be realised from the charge stability diagram. Identification of different orientation and position of the Nicotine molecule within the nanopore area can be made from specific regions of overlap between different charge states on the stability diagram that could be used as an electronic fingerprint for detection. This method could be advantageous and useful to detect the presence of Nicotine in smoke which is usually performed using chemical chromatography techniques.

  2. Single molecule transistor based nanopore for the detection of nicotine

    Energy Technology Data Exchange (ETDEWEB)

    Ray, S. J., E-mail: ray.sjr@gmail.com [Institute of Materials Science, Technical University of Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany)

    2014-12-28

    A nanopore based detection methodology was proposed and investigated for the detection of Nicotine. This technique uses a Single Molecular Transistor working as a nanopore operational in the Coulomb Blockade regime. When the Nicotine molecule is pulled through the nanopore area surrounded by the Source(S), Drain (D), and Gate electrodes, the charge stability diagram can detect the presence of the molecule and is unique for a specific molecular structure. Due to the weak coupling between the different electrodes which is set by the nanopore size, the molecular energy states stay almost unaffected by the electrostatic environment that can be realised from the charge stability diagram. Identification of different orientation and position of the Nicotine molecule within the nanopore area can be made from specific regions of overlap between different charge states on the stability diagram that could be used as an electronic fingerprint for detection. This method could be advantageous and useful to detect the presence of Nicotine in smoke which is usually performed using chemical chromatography techniques.

  3. Detection of individual gas molecules adsorbed on graphene.

    Science.gov (United States)

    Schedin, F; Geim, A K; Morozov, S V; Hill, E W; Blake, P; Katsnelson, M I; Novoselov, K S

    2007-09-01

    The ultimate aim of any detection method is to achieve such a level of sensitivity that individual quanta of a measured entity can be resolved. In the case of chemical sensors, the quantum is one atom or molecule. Such resolution has so far been beyond the reach of any detection technique, including solid-state gas sensors hailed for their exceptional sensitivity. The fundamental reason limiting the resolution of such sensors is fluctuations due to thermal motion of charges and defects, which lead to intrinsic noise exceeding the sought-after signal from individual molecules, usually by many orders of magnitude. Here, we show that micrometre-size sensors made from graphene are capable of detecting individual events when a gas molecule attaches to or detaches from graphene's surface. The adsorbed molecules change the local carrier concentration in graphene one by one electron, which leads to step-like changes in resistance. The achieved sensitivity is due to the fact that graphene is an exceptionally low-noise material electronically, which makes it a promising candidate not only for chemical detectors but also for other applications where local probes sensitive to external charge, magnetic field or mechanical strain are required.

  4. Detecting single DNA molecule interactions with optical microcavities (Presentation Recording)

    Science.gov (United States)

    Vollmer, Frank

    2015-09-01

    Detecting molecules and their interactions lies at the heart of all biosensor devices, which have important applications in health, environmental monitoring and biomedicine. Achieving biosensing capability at the single molecule level is, moreover, a particularly important goal since single molecule biosensors would not only operate at the ultimate detection limit by resolving individual molecular interactions, but they could also monitor biomolecular properties which are otherwise obscured in ensemble measurements. For example, a single molecule biosensor could resolve the fleeting interaction kinetics between a molecule and its receptor, with immediate applications in clinical diagnostics. We have now developed a label-free biosensing platform that is capable of monitoring single DNA molecules and their interaction kinetics[1], hence achieving an unprecedented sensitivity in the optical domain, Figure 1. We resolve the specific contacts between complementary oligonucleotides, thereby detecting DNA strands with less than 2.4 kDa molecular weight. Furthermore we can discern strands with single nucleotide mismatches by monitoring their interaction kinetics. Our device utilizes small glass microspheres as optical transducers[1,2, 3], which are capable of increasing the number of interactions between a light beam and analyte molecules. A prism is used to couple the light beam into the microsphere. Ourr biosensing approach resolves the specific interaction kinetics between single DNA fragments. The optical transducer is assembled in a simple three-step protocol, and consists of a gold nanorod attached to a glass microsphere, where the surface of the nanorod is further modified with oligonucleotide receptors. The interaction kinetics of an oligonucleotide receptor with DNA fragments in the surrounding aqueous solution is monitored at the single molecule level[1]. The light remains confined inside the sphere where it is guided by total internal reflections along a

  5. Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids.

    Science.gov (United States)

    Byers, Joshua C; Paulose Nadappuram, Binoy; Perry, David; McKelvey, Kim; Colburn, Alex W; Unwin, Patrick R

    2015-10-20

    Single molecule electrochemical detection (SMED) is an extremely challenging aspect of electroanalytical chemistry, requiring unconventional electrochemical cells and measurements. Here, SMED is reported using a "quad-probe" (four-channel probe) pipet cell, fabricated by depositing carbon pyrolytically into two diagonally opposite barrels of a laser-pulled quartz quadruple-barreled pipet and filling the open channels with electrolyte solution, and quasi-reference counter electrodes. A meniscus forms at the end of the probe covering the two working electrodes and is brought into contact with a substrate working electrode surface. In this way, a nanogap cell is produced whereby the two carbon electrodes in the pipet can be used to promote redox cycling of an individual molecule with the substrate. Anticorrelated currents generated at the substrate and tip electrodes, at particular distances (typically tens of nanometers), are consistent with the detection of single molecules. The low background noise realized in this droplet format opens up new opportunities in single molecule electrochemistry, including the use of ionic liquids, as well as aqueous solution, and the quantitative assessment and analysis of factors influencing redox cycling currents, due to a precisely known gap size.

  6. Nanopore detection of DNA molecules in magnesium chloride solutions

    Science.gov (United States)

    Zhang, Yin; Liu, Lei; Sha, Jingjie; Ni, Zhonghua; Yi, Hong; Chen, Yunfei

    2013-05-01

    High translocation speed of a DNA strand through a nanopore is a major bottleneck for nanopore detection of DNA molecules. Here, we choose MgCl2 electrolyte as salt solution to control DNA mobility. Experimental results demonstrate that the duration time for straight state translocation events in 1 M MgCl2 solution is about 1.3 ms which is about three times longer than that for the same DNA in 1 M KCl solution. This is because Mg2+ ions can effectively reduce the surface charge density of the negative DNA strands and then lead to the decrease of the DNA electrophoretic speed. It is also found that the Mg2+ ions can induce the DNA molecules binding together and reduce the probability of straight DNA translocation events. The nanopore with small diameter can break off the bound DNA strands and increase the occurrence probability of straight DNA translocation events.

  7. Detection of quorum-sensing-related molecules in Vibrio scophthalmi

    Directory of Open Access Journals (Sweden)

    Riedel Kathrin

    2008-08-01

    Full Text Available Abstract Background Cell-to-cell communication (also referred to as quorum sensing based on N-acyl-homoserine lactones (AHLs is a widespread response to environmental change in Gram-negative bacteria. AHLs seem to be highly variable, both in terms of the acyl chain length and in the chemical structure of the radicals. Another quorum sensing pathway, the autoinducer-2-based system, is present both in Gram-positive and Gram-negative bacteria. In this study the presence of signal molecules belonging to both quorum sensing signalling pathways was analysed in the marine symbiotic species Vibrio scophthalmi. Results Three AHL-like signal molecules were detected in V. scophthalmi supernatants with the Agrobacterium tumefaciens sensor assay. This observation was further supported by the decrease in the presence of these signal molecules after cloning and expression of lactonase AiiA from Bacillus cereus in the V. scophthalmi strains. One of the signal molecules was identified as N-(3-hydroxy dodecanoyl-L-homoserine lactone. V. scophthalmi was also shown to carry a functional LuxS synthase. The coding sequence for a luxS-like gene was obtained showing a maximum similarity of 78% with Vibrio vulnificus. Analysis of the translated sequence revealed that the sequenced luxS gene carried the conserved domain, which is common to luxS sequences found in other species, and which is essential for LuxS enzymatic activity. Conclusion The data are consistent with the presence of quorum-sensing signal molecules from both AHL- and autoinducer 2-based quorum sensing systems in V. scophthalmi, which are homologous to others previously described in various Vibrio species. How this bacterium interacts with other bacteria and eukaryotic cells to compete ecologically with other intestinal bacteria present in the fish Scophthalmus maximus warrants further investigation.

  8. A new microcavity design for single molecule detection

    International Nuclear Information System (INIS)

    Steiner, M.; Schleifenbaum, F.; Stupperich, C.; Failla, A.V.; Hartschuh, A.; Meixner, A.J.

    2006-01-01

    We present a new microcavity design which allows for efficient detection of single molecules by measuring the molecular fluorescence emission coupled into a resonant cavity mode. The Fabry-Perot-type microresonator consists of two silver mirrors separated by a thin polymer film doped with dye molecules in ultralow concenctration. By slightly tilting one of the mirrors different cavity lengths can be selected within the same sample. Locally, on a μm scale, the microcavity still acts as a planar Fabry-Perot resonator. Using scanning confocal fluorescence microscopy, single emitters on resonance with a single mode of the microresonator can be spatially addressed. Our microcavity is demonstrated to be well-suited for investigating the coupling mechanism between single quantum emitters and single modes of the electromagnetic field. The microcavity layout could be integrated in a lab-on-a-microchip design for ultrasensitive microfluidic analytics and can be considered as an important improvement for single photon sources based on single molecules operating at room temperature

  9. Few molecule SERS detection using nanolens based plasmonic nanostructure: application to point mutation detection

    KAUST Repository

    Das, Gobind

    2016-10-27

    Advancements in nanotechnology fabrication techniques allow the possibility to design and fabricate a device with a minimum gap (<10 nm) between the composing nanostructures in order to obtain better control over the creation and spatial definition of plasmonic hot-spots. The present study is intended to show the fabrication of nanolens and their application to single/few molecules detection. Theoretical simulations were performed on different designs of real structures, including comparison of rough and smooth surfaces. Various molecules (rhodamine 6G, benzenethiol and BRCA1/BRCT peptides) were examined in this regard. Single molecule detection was possible for synthetic peptides, with a possible application in early detection of diseases. © The Royal Society of Chemistry.

  10. Fluorescence detection of organic molecules in the Jovian atmosphere.

    Science.gov (United States)

    Levine, J S; Rogowski, R S

    1975-07-01

    A search for fluorescent emission due to the presence of possible organic molecules in the Jovian atmosphere is described. We first consider natural Jovian fluorescent emission excited by precipitating auroral particles. Due to our lack of knowledge of the Jovian precipitation particle energies and fluxes we next consider fluorescent emission excited by a laser system aboard a Jupiter spacecraft. Laser-induced fluorescence is routinely used to monitor trace constituents and pollutants in the terrestrial atmosphere. Several spacecraft laser systems are currently under development. Our calculations indicate that laser-induced fluorescent detection is approximately two orders of magnitude more sensitive than rocket ultraviolet measurements of possible Jovian absorption features at 2600 A that have been attributed to the presence of adenine or benzene.

  11. Magnesium Sulfate as a Key Mineral for the Detection of Organic Molecules on Mars Using Pyrolysis

    Science.gov (United States)

    Francois, P.; Szopa, C.; Buch, A.; Coll, P.; McAdam, A. C.; Mahaffy, P. R.; Freissinet, C.; Glavin, D. P.; Navarro-Gonzalez, R.; Cabane, M.

    2016-01-01

    Pyrolysis of soil or rock samples is the preferred preparation technique used on Mars to search for organic molecules up today. During pyrolysis, oxichlorines present in the soil of Mars release oxidant species that alter the organic molecules potentially contained in the samples collected by the space probes.This process can explain the difficulty experienced by in situ exploration probes to detect organic materials in Mars soil samples until recently. Within a few months, the Curiosity rover should reach and analyze for the first time soils rich in sulfates which could induce a different behavior of the organics during the pyrolysis compared with the types of soils analyzed up today. For this reason, we systematically studied the pyrolysis of organic molecules trapped in magnesium sulfate, in the presence or absence of calcium perchlorate. Our results show that organics trapped in magnesium sulfate can undergo some oxidation and sulfuration during the pyrolysis. But these sulfates are also shown to protect organics trapped inside the crystal lattice and/or present in fluid inclusions from the oxidation induced by the decomposition of calcium perchlorate and probably other oxychlorine phases currently detected on Mars. Trapped organics may also be protected from degradation processes induced by other minerals present in the sample, at least until these organics are released from the pyrolyzed sulfate mineral (700C in our experiment). Hence, we suggest magnesium sulfate as one of the minerals to target in priority for the search of organic molecules by the Curiosity and ExoMars 2018 rovers.

  12. Singlet oxygen: photosensitized generation, detection and reaction with organic molecules

    International Nuclear Information System (INIS)

    Barik, Atanu; Indira Priyadarsini, K.; Hari Mohan; Bajaj, P.N.; Sapre, A.V.; Mittal, J.P.; Mukherjee, T.

    2006-10-01

    Singlet molecular oxygen ( 1 O 2 ) is an excited state of molecular oxygen, having antiparallel spin in the same π antibonding orbital. The study of singlet oxygen production and reactivity has emerged as a rich and diverse area, with implication in diverse fields, such as synthetic chemistry, polymer chemistry, photodynamic therapy, etc. There are several known methods to produce singlet oxygen, and also various techniques employed to detect it. Out of these, photosensitization method is the most popular one. In this article, photosensitized production of singlet oxygen from triplet oxygen and photosensitizers in presence of light, and its detection by the infrared luminescence at 1270 nm have been presented. Further, some results using different types of photosensitizers, effect of solvent on singlet oxygen quantum yields and lifetime have been discussed. The quenching rate constants of singlet oxygen have been determined with different types of organic molecules such as derivatives of thiourea and its analogues, hydroxy indoles and antioxidants and the results have been presented. (author)

  13. Analysis of complexity measures and information planes of selected molecules in position and momentum spaces.

    Science.gov (United States)

    Esquivel, Rodolfo O; Angulo, Juan Carlos; Antolín, Juan; Dehesa, Jesús S; López-Rosa, Sheila; Flores-Gallegos, Nelson

    2010-07-14

    The Fisher-Shannon and LMC shape complexities and the Shannon-disequilibrium, Fisher-Shannon and Fisher-disequilibrium information planes, which consist of two localization-delocalization factors, are computed in both position and momentum spaces for the one-particle densities of 90 selected molecules of various chemical types, at the CISD/6-311++G(3df,2p) level of theory. We found that while the two measures of complexity show general trends only, the localization-delocalization planes clearly exhibit chemically significant patterns. Several molecular properties (energy, ionization potential, total dipole moment, hardness, electrophilicity) are analyzed and used to interpret and understand the chemical nature of the composite information-theoretic measures above mentioned. Our results show that these measures detect not only randomness or localization but also pattern and organization.

  14. Evolution of organic molecules under Mars-like UV radiation conditions in space and laboratory

    OpenAIRE

    Rouquette, Laura; Stalport, Fabien; Cottin, Hervé; Coll, Patrice; Szopa, Cyril; Saiagh, Kafila; Poch, Olivier; Khalaf, Diana; Chaput, Didier; Grira, Katia; Dequaire, Tristan

    2017-01-01

    International audience; The detection and identification of organic molecules at Mars are of prime importance, as some of these molecules are life precursors and components. While in situ planetary missions are searching for them, it is essential to understand how organic molecules evolve and are preserved at the surface of Mars. Indeed the harsh conditions of the environment of Mars such as ultraviolet (UV) radiation or oxidative processes could explain the low abundance and diversity of org...

  15. Dr. K. Rangadhama Rao memorial lecture - 1979: Molecules in interstellar space

    International Nuclear Information System (INIS)

    Asundi, R.K.

    1980-01-01

    A large number of di- and polyatomic molecules including organic molecules involved in synthesis of amino-acids has been discovered in interstellar medium by radio frequency spectroscopy techniques during the last decade. Particularly significant among them are vinyl-cyanide (H 2 C=CHCN) having a double bond c = c and, the whole series of long chain linear molecules, HCN, HC 3 N, HC 5 N, HC 7 N and HC 9 N, the last being discovered in 1978 in interstellar space, but not yet on earth. A detailed knowledge of the state in which molecules are found existing in different parts of interstellar space is expected to throw useful light on the origin of celestial bodies like stars, etc. and of life as we know it. The study of interstellar molecules has thus become an area with a hectic pace of discovery for several disciplines of Science. (author)

  16. Methods for the selective detection of alkyne-presenting molecules and related compositions and systems

    Science.gov (United States)

    Valdez, Carlos A.; Vu, Alexander K.

    2017-10-17

    Provided herein are methods for selectively detecting an alkyne-presenting molecule in a sample and related detection reagents, compositions, methods and systems. The methods include contacting a detection reagent with the sample for a time and under a condition to allow binding of the detection reagent to the one or more alkyne-presenting molecules possibly present in the matrix to the detection reagent. The detection reagent includes an organic label moiety presenting an azide group. The binding of the azide group to the alkyne-presenting molecules results in emission of a signal from the organic label moiety.

  17. Molecules in Space: A Chemistry lab using Radio Astronomy

    Science.gov (United States)

    Lekberg, M. J.; Pratap, P.

    2000-12-01

    We present the results of a laboratory exercise developed with the support of the NSF Research Experiences for Teachers program at MIT Haystack Observatory. The exercise takes the students beyond the traditional test tubes of a chemistry laboratory into the interstellar medium, where the same principles that they study about in the classroom are found to hold. It also utilizes the true multi-disciplinary nature of radio astronomy and allows the students to realize how much can be learnt by studying the universe at various wavelengths. The astronomical chemistry laboratory is presented wherein students from Chelmsford High School in Massachusetts operate the 37-m telescope at Haystack Observatory via the internet to observe radio signals from galactic chemicals. The laboratory is designed to be the means by which students witness physical evidence for molecular and orbital shapes by observing the radio emission from rotating dipoles. The laboratory described is a lynch pin activity for an integrated unit that moves from the valance shell electron configurations through molecular and orbital geometry to an understanding that many physical and chemical properties of chemicals are ultimately dependent upon the shape/geometry and consequently, dipole of the molecule. Students are expected to interpret and evaluate the nature of molecular dipoles and account for the diversity of rotational spectra using their conceptual knowledge of bonding orbital theory and their knowledge of the electronic atom. Flexibility in the lab allows students to identify individual chemicals by cross referencing radio emission from the galactic sources they have chosen against a prepared catalogue listing or by choosing to "listen" for specific chemicals at exact frequencies. A teacher resource manual containing information and data on a variety of daytime galactic source and individual chemical flux densities of molecular candidates has been prepared. Collaborative exercises and activities

  18. Detection device for inside of space

    International Nuclear Information System (INIS)

    Kojima, Kosuke.

    1996-01-01

    A securing plate is disposed to a support column which can be inserted to a space, and a rotational member on which equipments for detection are loaded is disposed rotatably in the longitudinal direction of the support column at a predetermined distance from the securing plate. Shape memory alloy wires that shrink when current is supplied are stretched circumferentially each at a predetermined distance obliquely relative to the support column between the rotational member and the securing plate. In addition, there are disposed a sensor for detecting the rotational angle of the rotational member, a calculator for determining the deviation of the angle of the rotation based on the difference of the detected rotational angle and a predetermined rotational angle as a reference, a deviation counter for obtaining deviation count signals based on the deviation of the rotational angle, a D-A convertor for converting the deviation count signals to analog signals, a pulse width modulation device for duty ratio control based on the analog signals and output pulse signals, and a power amplifier for amplifying the pulse signals and applying them to the shape memory wires. Since the device is reduced in the size and weight, handling is facilitated, and the rotational angle can be controlled accurately. The device can be used for detection of an end plate in a pressure vessel. (N.H.)

  19. A simple hydrazine based molecule for selective detection of ...

    Indian Academy of Sciences (India)

    chemsci

    certain diseases like osteoporosis, osteosclerosis, dental fluorosis and skeletal fluorosis. In recent times, the sci- entific community is looking for chemoreceptors which can detect F. − in both chromogenic and photolumines- cent way, which is less expensive than the existing phys- ical methods for detection of fluoride and ...

  20. Successful Noninvasive Trisomy 18 Detection Using Single Molecule Sequencing

    NARCIS (Netherlands)

    van den Oever, Jessica M. E.; Balkassmi, Sahila; Johansson, Lennart F.; van Scheltema, Phebe N. Adama; Suijkerbuijk, Ron F.; Hoffer, Mariette J. V.; Sinke, Richard J.; Bakker, Egbert; Sikkema-Raddatz, Birgit; Boon, Elles M. J.

    BACKGROUND: Noninvasive trisomy 21 detection performed by use of massively parallel sequencing is achievable with high diagnostic sensitivity and low false-positive rates. Detection of fetal trisomy 18 and 13 has been reported as well but seems to be less accurate with the use of this approach. The

  1. Network Community Detection on Metric Space

    Directory of Open Access Journals (Sweden)

    Suman Saha

    2015-08-01

    Full Text Available Community detection in a complex network is an important problem of much interest in recent years. In general, a community detection algorithm chooses an objective function and captures the communities of the network by optimizing the objective function, and then, one uses various heuristics to solve the optimization problem to extract the interesting communities for the user. In this article, we demonstrate the procedure to transform a graph into points of a metric space and develop the methods of community detection with the help of a metric defined for a pair of points. We have also studied and analyzed the community structure of the network therein. The results obtained with our approach are very competitive with most of the well-known algorithms in the literature, and this is justified over the large collection of datasets. On the other hand, it can be observed that time taken by our algorithm is quite less compared to other methods and justifies the theoretical findings.

  2. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.

    2017-09-12

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  3. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Science.gov (United States)

    Sansinena, Jose-Maria [Los Alamos, NM; Redondo, Antonio [Los Alamos, NM; Olazabal, Virginia [Los Alamos, NM; Hoffbauer, Mark A [Los Alamos, NM; Akhadov, Elshan A [Los Alamos, NM

    2009-12-29

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  4. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2017-10-31

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  5. Nanofabrication of SERS Substrates for Single/Few Molecules Detection

    KAUST Repository

    Melino, Gianluca

    2015-05-04

    Raman spectroscopy is among the most widely employed methods to investigate the properties of materials in several fields of study. Evolution in materials science allowed us to fabricate suitable substrates, at the nanoscale, capable to enhance the electromagnetic field of the signals coming from the samples which at this range turn out to be in most cases singles or a few molecules. This particular variation of the classical technique is called SERS (Surface Enanched Raman Spectroscopy). In this work, the enhancement of the electromagnetic field is obtained by manipulation of the optical properties of metals with respect to their size. By using electroless deposition (bottom up technique), gold and silver nanoparticles were deposited in nanostructured patterns obtained on silicon wafers by means of electron beam lithography (top down technique). Rhodamine 6G in aqueous solution at extremely low concentration (10-8 M) was absorbed on the resultant dimers and the collection of the Raman spectra demonstrated the high efficiency of the substrates.

  6. Clearance Kinetics and Clearance Routes of Molecules From the Suprachoroidal Space After Microneedle Injection.

    Science.gov (United States)

    Chiang, Bryce; Wang, Ke; Ethier, C Ross; Prausnitz, Mark R

    2017-01-01

    To determine clearance kinetics and routes of clearance of molecules from the suprachoroidal space (SCS) of live New Zealand White rabbits. Suprachoroidal space collapse rate and pressure changes after microneedle injection into SCS were determined. Fluorescent fundus images were acquired to determine clearance rates of molecules ranging in size from 332 Da to 2 MDa. Microneedle injections of fluorescein were performed, and samples were taken from various sites over time to determine amount of fluorescein exiting the eye. Clearance transport was modeled theoretically and compared with experimental data. After injection, pressures in SCS and vitreous humor spiked and returned to baseline within 20 minutes; there was no difference between these two pressures. Suprachoroidal space collapse occurred within 40 minutes. One hour after fluorescein injection, 46% of fluorescein was still present in the eye, 15% had transported across sclera, 6% had been cleared by choroidal vasculature, and 4% had exited via leakage pathways. Characteristic clearance time increased in proportion with molecular radius, but total clearance of 2 MDa FITC-dextran was significantly slower (21 days) than smaller molecules. These data generally agreed with predictions from a theoretical model of molecular transport. Guided by experimental data in the context of model predictions, molecular clearance from SCS occurred in three regimes: (1) on a time scale of approximately 10 minutes, fluid and molecules exited SCS by diffusion into sclera and choroid, and by pressure-driven reflux via transscleral leakage sites; (2) in approximately 1 hour, molecules cleared from choroid by blood flow; and (3) in 1 to 10 hours, molecules cleared from sclera by diffusion and convection.

  7. Detection of a single enzyme molecule based on a solid-state nanopore sensor.

    Science.gov (United States)

    Tan, ShengWei; Gu, DeJian; Liu, Hang; Liu, QuanJun

    2016-04-15

    The nanopore sensor as a high-throughput and low-cost technology can detect a single molecule in a solution. In the present study, relatively large silicon nitride (Si3N4) nanopores with diameters of ∼28 and ∼88 nm were fabricated successfully using a focused Ga ion beam. We have used solid-state nanopores with various sizes to detect the single horseradish peroxidase (HRP) molecule and for the first time analyzed single HRP molecular translocation events. In addition, a real-time monitored single enzyme molecular biochemical reaction and a translocation of the product of enzyme catalysis substrates were investigated by using a Si3N4 nanopore. Our nanopore system showed a high sensitivity in detecting single enzyme molecules and a real-time monitored single enzyme molecular biochemical reaction. This method could also be significant for studying gene expression or enzyme dynamics at the single-molecule level.

  8. SISGR: Room Temperature Single-Molecule Detection and Imaging by Stimulated Emission Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xiaoliang Sunney [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology

    2017-03-13

    Single-molecule spectroscopy has made considerable impact on many disciplines including chemistry, physics, and biology. To date, most single-molecule spectroscopy work is accomplished by detecting fluorescence. On the other hand, many naturally occurring chromophores, such as retinal, hemoglobin and cytochromes, do not have detectable fluorescence. There is an emerging need for single-molecule spectroscopy techniques that do not require fluorescence. In the last proposal period, we have successfully demonstrated stimulated emission microscopy, single molecule absorption, and stimulated Raman microscopy based on a high-frequency modulation transfer technique. These first-of-a- kind new spectroscopy/microscopy methods tremendously improved our ability to observe molecules that fluorescence weakly, even to the limit of single molecule detection for absorption measurement. All of these methods employ two laser beams: one (pump beam) excites a single molecule to a real or virtual excited state, and the other (probe beam) monitors the absorption/emission property of the single. We extract the intensity change of the probe beam with high sensitivity by implementing a high-frequency phase-sensitive detection scheme, which offers orders of magnitude improvement in detection sensitivity over direct absorption/emission measurement. However, single molecule detection based on fluorescence or absorption is fundamentally limited due to their broad spectral response. It is important to explore other avenues in single molecule detection and imaging which provides higher molecular specificity for studying a wide variety of heterogeneous chemical and biological systems. This proposal aimed to achieve single-molecule detection sensitivity with near resonance stimulated Raman scattering (SRS) microscopy. SRS microscopy was developed in our lab as a powerful technique for imaging heterogeneous samples based on their intrinsic vibrational contrasts, which provides much higher molecular

  9. Exploring sets of molecules from patents and relationships to other active compounds in chemical space networks

    Science.gov (United States)

    Kunimoto, Ryo; Bajorath, Jürgen

    2017-09-01

    Patents from medicinal chemistry represent a rich source of novel compounds and activity data that appear only infrequently in the scientific literature. Moreover, patent information provides a primary focal point for drug discovery. Accordingly, text mining and image extraction approaches have become hot topics in patent analysis and repositories of patent data are being established. In this work, we have generated network representations using alternative similarity measures to systematically compare molecules from patents with other bioactive compounds, visualize similarity relationships, explore the chemical neighbourhood of patent molecules, and identify closely related compounds with different activities. The design of network representations that combine patent molecules and other bioactive compounds and view patent information in the context of current bioactive chemical space aids in the analysis of patents and further extends the use of molecular networks to explore structure-activity relationships.

  10. Generation, Detection and characterization of Gas-Phase Transition Metal containing Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Steimle, Timothy [Arizona State Univ., Tempe, AZ (United States)

    2015-12-15

    the number and nature of the unpaired electrons. Analysis of the hyperfine interactions (i.e. Fermi-contact, nuclear electric quadrupole, etc.) is particularly insightful because it results from the interaction of nuclei with non-zero spin and the chemically important valence electrons. The bulk of the spectroscopic techniques used in these studies exploit the sensitivity of laser induced fluorescence (LIF) detection. The spectroscopic schemes employed include: a) cw and pulsed laser field-free(FF) excitation and dispersed LIF (DLIF); b) optical Stark; c) optical Zeeman; d) pump/probe microwave double resonance (PPMODR); e) fluorescence lifetimes, and f) resonant and non-resonant two-photon ionization TOF mass spectrometry. Vibrational spacing, force constants and electronic states distributions are derived from the analysis of pulsed dye laser excitation and DLIF spectra. Geometric structure (bond lengths and angles) and hyperfine parameters are derived from the analysis of cw-laser LIF and PPMODR spectra. Permanent electric dipole moments, mel,, and magnetic dipole moments, mm, are derived from the analysis of optical Stark and Zeeman spectra, respectively. Transition moments are derived from the analysis of radiative lifetimes. A supersonic molecular beam sample of these ephemeral molecules is generated by skimming the products of either a laser ablation/reaction source or a d.c. discharge source.

  11. Nucleic acid detection technologies and marker molecules in bacterial diagnostics.

    Science.gov (United States)

    Scheler, Ott; Glynn, Barry; Kurg, Ants

    2014-05-01

    There is a growing need for quick and reliable methods for microorganism detection and identification worldwide. Although traditional culture-based technologies are trustworthy and accurate at a relatively low cost, they are also time- and labor-consuming and are limited to culturable bacteria. Those weaknesses have created a necessity for alternative technologies that are capable for faster and more precise bacterial identification from medical, food or environmental samples. The most common current approach is to analyze the nucleic acid component of analyte solution and determine the bacterial composition according to the specific nucleic acid profiles that are present. This review aims to give an up-to-date overview of different nucleic acid target sequences and respective analytical technologies.

  12. Hydrogen leak detection in the Space Shuttle

    Science.gov (United States)

    Barile, Ronald G

    1992-01-01

    This study focuses on a helium gas jet flowing into room air. Measurements of helium concentration and velocity in the jet-air mixture are reported. The objective is to learn about jet characteristics so that dynamically similar hydrogen leaks may be located in the Space Shuttle. The hazardous gas detection system (HGDS) in the mobile launch pad uses mass spectrometers to monitor the shuttle environment for leaks. The mass spectrometers are fed by long sample tubes which draw gas from the payload bay, mid body, aft engine compartment and external tank. The overall purpose of this study is to improve the HGDS especially in its potential for locating hydrogen leaks. A rapid-response leak detection experiment was designed, built, and tested, following on the work done in this program last summer. The apparatus included a Perkin Elmer MGA-1200 mass spectrometer and air velocity transducer, both monitored by a Macintosh IIFX computer using LabVIEW software. A jet of helium flowing into the lab air simulated a gas leak. Steady helium or hydrogen-nitrogen jets were logged for concentration and velocity, and the power spectral density of each was computed. Last year, large eddies and vortices were visually seen with Schlieren imaging, and they were detected in the time plots of the various instruments. The response time of the MGA-1200 was found in the range of 0.05 to 0.1 sec. Pulsed concentration waves were clearly detected at 25 cycles per sec by spectral analysis of MGA data. No peaks were detected in the power spectrum, so in the present study, 10 Hz bandwidth-averaged power levels were examined at regular frequency intervals. The practical consequences of last year's study are as follows: sampling frequency should be increased above the present rate of 1 sample per second so that transients could be observed and analyzed with frequency response methods. Many more experiments and conditions were observed in this second summer, including the effects of orifice diameter

  13. Conventional, molecular methods and biomarkers molecules in detection of septicemia

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Arabestani

    2015-01-01

    Full Text Available Sepsis is a leading cause of morbidity and mortality in hospitalized patients worldwide and based on studies, 30-40% of all cases of severe sepsis and septic shock results from the blood stream infections (BSIs. Identifying of the disease, performing laboratory tests, and consequently treatment are factors that required for optimum management of BSIs. In addition, applying precise and immediate identification of the etiologic agent is a prerequisite for specific antibiotic therapy of pathogen and thereby decreasing mortality rates. The diagnosis of sepsis is difficult because clinical signs of sepsis often overlap with other noninfectious cases of systemic inflammation. BSIs are usually diagnosed by performing a series of techniques such as blood cultures, polymerase chain reaction-based methods, and biomarkers of sepsis. Extremely time-consuming even to take up to several days is a major limitation of conventional methods. In addition, yielding false-negative results due to fastidious and slow-growing microorganisms and also in case of antibiotic pretreated samples are other limitations. In comparison, molecular methods are capable of examining a blood sample obtained from suspicious patient with BSI and gave the all required information to prescribing antimicrobial therapy for detected bacterial or fungal infections immediately. Because of an emergency of sepsis, new methods are being developed. In this review, we discussed about the most important sepsis diagnostic methods and numbered the advantage and disadvantage of the methods in detail.

  14. Detection of kinetic change points in piece-wise linear single molecule motion

    Science.gov (United States)

    Hill, Flynn R.; van Oijen, Antoine M.; Duderstadt, Karl E.

    2018-03-01

    Single-molecule approaches present a powerful way to obtain detailed kinetic information at the molecular level. However, the identification of small rate changes is often hindered by the considerable noise present in such single-molecule kinetic data. We present a general method to detect such kinetic change points in trajectories of motion of processive single molecules having Gaussian noise, with a minimum number of parameters and without the need of an assumed kinetic model beyond piece-wise linearity of motion. Kinetic change points are detected using a likelihood ratio test in which the probability of no change is compared to the probability of a change occurring, given the experimental noise. A predetermined confidence interval minimizes the occurrence of false detections. Applying the method recursively to all sub-regions of a single molecule trajectory ensures that all kinetic change points are located. The algorithm presented allows rigorous and quantitative determination of kinetic change points in noisy single molecule observations without the need for filtering or binning, which reduce temporal resolution and obscure dynamics. The statistical framework for the approach and implementation details are discussed. The detection power of the algorithm is assessed using simulations with both single kinetic changes and multiple kinetic changes that typically arise in observations of single-molecule DNA-replication reactions. Implementations of the algorithm are provided in ImageJ plugin format written in Java and in the Julia language for numeric computing, with accompanying Jupyter Notebooks to allow reproduction of the analysis presented here.

  15. Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide.

    Science.gov (United States)

    Belloche, Arnaud; Garrod, Robin T; Müller, Holger S P; Menten, Karl M

    2014-09-26

    The largest noncyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times that of its straight-chain structural isomer. This detection suggests that branched carbon-chain molecules may be generally abundant in the ISM. Our astrochemical model indicates that both isomers are produced within or upon dust grain ice mantles through the addition of molecular radicals, albeit via differing reaction pathways. The production of iso-propyl cyanide appears to require the addition of a functional group to a nonterminal carbon in the chain. Its detection therefore bodes well for the presence in the ISM of amino acids, for which such side-chain structure is a key characteristic. Copyright © 2014, American Association for the Advancement of Science.

  16. Communication: atomic force detection of single-molecule nonlinear optical vibrational spectroscopy.

    Science.gov (United States)

    Saurabh, Prasoon; Mukamel, Shaul

    2014-04-28

    Atomic Force Microscopy (AFM) allows for a highly sensitive detection of spectroscopic signals. This has been first demonstrated for NMR of a single molecule and recently extended to stimulated Raman in the optical regime. We theoretically investigate the use of optical forces to detect time and frequency domain nonlinear optical signals. We show that, with proper phase matching, the AFM-detected signals closely resemble coherent heterodyne-detected signals. Applications are made to AFM-detected and heterodyne-detected vibrational resonances in Coherent Anti-Stokes Raman Spectroscopy (χ((3))) and sum or difference frequency generation (χ((2))).

  17. Searching for Bio-Precursors and Complex Organic Molecules in Space using the GBT

    Science.gov (United States)

    Cordiner, M.; Charnley, S.; Kisiel, Z.

    2012-01-01

    Using the latest microwave receiver technology, large organic molecules with abundances as low as approx. 10(exp -11) times that of molecular hydrogen are detectable in cold interstellar clouds via their rotational emission line spectra. We report new observations to search for complex molecules, including molecules of possible pre-biotic importance, using the newly-commissioned Kband focal plane array (KFPA) of the NRAO Robert C. Byrd Green Bank Telescope. Spectra are presented of the dense molecular cloud TMC-1, showing strict upper limits on the level of emission from nitrogen-bearing rings pyrimidine, quinoline and iso-quinoline, carbon-chain oxides C60, C70, HC60 and HC70, and the carbon-chain anion C4H-. The typical RMS brightness temperature noise levels we achieved are approx. 1 mK at around 20 GHz.

  18. Detection of Individual Molecules and Ions by Carbon Nanotube-Based Differential Resistive Pulse Sensor.

    Science.gov (United States)

    Peng, Ran; Tang, Xiaowu Shirley; Li, Dongqing

    2018-04-01

    This paper presents a new method of sensing single molecules and cations by a carbon nanotube (CNT)-based differential resistive pulse sensing (RPS) technique on a nanofluidic chip. A mathematical model for multichannel RPS systems is developed to evaluate the CNT-based RPS signals. Individual cations, rhodamine B dye molecules, and ssDNAs are detected successfully with high resolution and high signal-to-noise ratio. Differentiating ssDNAs with 15 and 30 nucleotides are achieved. The experimental results also show that translocation of negatively charged ssDNAs through a CNT decreases the electrical resistance of the CNT channel, while translocation of positively charged cations and rhodamine B molecules increases the electrical resistance of the CNT. The CNT-based nanofluidic device developed in this work provides a new avenue for single-molecule/ion detection and offers a potential strategy for DNA sequencing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Detection of gas molecules on single Mn adatom adsorbed graphyne: a DFT-D study

    Science.gov (United States)

    Lu, Zhansheng; Lv, Peng; Ma, Dongwei; Yang, Xinwei; Li, Shuo; Yang, Zongxian

    2018-02-01

    As one of the prominent applications in intelligent systems, gas sensing technology has attracted great interest in both industry and academia. In the current study, the pristine graphyne (GY) without and with a single Mn atom is investigated to detect the gas molecules (CO, CH4, CO2, NH3, NO and O2). The pristine GY is promising to detect O2 molecules because of its chemical adsorption on GY with large electron transfer. The great stability of the Mn/GY is found, and the Mn atom prefers to anchor at the alkyne ring as a single atom. Upon single Mn atom anchoring, the sensitivity and selectivity of GY based gas sensors is significantly improved for various molecules, except CH4. The recovery time of the Mn/GY after detecting the gas molecules may help to appraise the detection efficiency for the Mn/GY. The current study will help to understand the mechanism of detecting the gas molecules, and extend the potentially fascinating applications of GY-based materials.

  20. Mass amplifying probe for sensitive fluorescence anisotropy detection of small molecules in complex biological samples.

    Science.gov (United States)

    Cui, Liang; Zou, Yuan; Lin, Ninghang; Zhu, Zhi; Jenkins, Gareth; Yang, Chaoyong James

    2012-07-03

    Fluorescence anisotropy (FA) is a reliable and excellent choice for fluorescence sensing. One of the key factors influencing the FA value for any molecule is the molar mass of the molecule being measured. As a result, the FA method with functional nucleic acid aptamers has been limited to macromolecules such as proteins and is generally not applicable for the analysis of small molecules because their molecular masses are relatively too small to produce observable FA value changes. We report here a molecular mass amplifying strategy to construct anisotropy aptamer probes for small molecules. The probe is designed in such a way that only when a target molecule binds to the probe does it activate its binding ability to an anisotropy amplifier (a high molecular mass molecule such as protein), thus significantly increasing the molecular mass and FA value of the probe/target complex. Specifically, a mass amplifying probe (MAP) consists of a targeting aptamer domain against a target molecule and molecular mass amplifying aptamer domain for the amplifier protein. The probe is initially rendered inactive by a small blocking strand partially complementary to both target aptamer and amplifier protein aptamer so that the mass amplifying aptamer domain would not bind to the amplifier protein unless the probe has been activated by the target. In this way, we prepared two probes that constitute a target (ATP and cocaine respectively) aptamer, a thrombin (as the mass amplifier) aptamer, and a fluorophore. Both probes worked well against their corresponding small molecule targets, and the detection limits for ATP and cocaine were 0.5 μM and 0.8 μM, respectively. More importantly, because FA is less affected by environmental interferences, ATP in cell media and cocaine in urine were directly detected without any tedious sample pretreatment. Our results established that our molecular mass amplifying strategy can be used to design aptamer probes for rapid, sensitive, and selective

  1. PAREMD: A parallel program for the evaluation of momentum space properties of atoms and molecules

    Science.gov (United States)

    Meena, Deep Raj; Gadre, Shridhar R.; Balanarayan, P.

    2018-03-01

    The present work describes a code for evaluating the electron momentum density (EMD), its moments and the associated Shannon information entropy for a multi-electron molecular system. The code works specifically for electronic wave functions obtained from traditional electronic structure packages such as GAMESS and GAUSSIAN. For the momentum space orbitals, the general expression for Gaussian basis sets in position space is analytically Fourier transformed to momentum space Gaussian basis functions. The molecular orbital coefficients of the wave function are taken as an input from the output file of the electronic structure calculation. The analytic expressions of EMD are evaluated over a fine grid and the accuracy of the code is verified by a normalization check and a numerical kinetic energy evaluation which is compared with the analytic kinetic energy given by the electronic structure package. Apart from electron momentum density, electron density in position space has also been integrated into this package. The program is written in C++ and is executed through a Shell script. It is also tuned for multicore machines with shared memory through OpenMP. The program has been tested for a variety of molecules and correlated methods such as CISD, Møller-Plesset second order (MP2) theory and density functional methods. For correlated methods, the PAREMD program uses natural spin orbitals as an input. The program has been benchmarked for a variety of Gaussian basis sets for different molecules showing a linear speedup on a parallel architecture.

  2. Improving Precision of Proximity Ligation Assay by Amplified Single Molecule Detection

    OpenAIRE

    Ke, Rongqin; Nong, Rachel Yuan; Fredriksson, Simon; Landegren, Ulf; Nilsson, Mats

    2013-01-01

    Proximity ligation assay (PLA) has been proven to be a robust protein detection method. The technique is characterized by high sensitivity and specificity, but the assay precision is probably limited by the PCR readout. To investigate this potential limitation and to improve precision, we developed a digital proximity ligation assay for protein measurement in fluids based on amplified single molecule detection. The assay showed significant improvements in precision, and thereby also detection...

  3. Space-based detection of space debris by photometric and polarimetric characteristics

    Science.gov (United States)

    Pang, Shuxia; Wang, Hu; Lu, Xiaoyun; Shen, Yang; Pan, Yue

    2017-10-01

    The number of space debris has been increasing dramatically in the last few years, and is expected to increase as much in the future. As the orbital debris population grows, the risk of collision between debris and other orbital objects also grows. Therefore, space debris detection is a particularly important task for space environment security, and then supports for space debris modeling, protection and mitigation. This paper aims to review space debris detection systematically and completely. Firstly, the research status of space debris detection at home and abroad is presented. Then, three kinds of optical observation methods of space debris are summarized. Finally, we propose a space-based detection scheme for space debris by photometric and polarimetric characteristics.

  4. Space Applications for Ensemble Detection and Analysis

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA makes extensive investments to circumvent the engineering challenges posed by naturally occurring random processes for which conventional statistics do not...

  5. Detection of Quorum Sensing Molecules and Biofilm Formation in Ralstonia solanacearum.

    Science.gov (United States)

    Kumar, J Shiva; Umesha, S; Prasad, K Shiva; Niranjana, P

    2016-03-01

    Many bacteria use small diffusible signaling molecules to communicate each other termed as quorum sensing (QS). Most Gram-negative bacteria use acyl homoserine lactone (AHL) as QS signal molecules. Using these signaling molecules, bacteria are able to express specific genes in response to population density. This work aimed to detect the production of QS signal molecules and biofilm formation in Ralstonia solanacearum isolated from various diseased tomato plants with symptoms of bacterial wilt. A total of 30 R. solanacearum strains were investigated for the production of QS signal molecules using Chromobacterium violaceum CV026 and Agrobacterium tumefaciens NT1 (pZLR4) biosensor systems. All 30 bacterial isolates from various bacterial wilt-affected tomato plants produced AHL molecules that induced the biosensor. The microtiter plate assay demonstrated that of the 30 bacterial isolates, 60 % formed biofilm, among which four isolates exhibited a higher degree of biofilm formation. The biofilm-inducing factor was purified from these four culture supernatants. The structure of the responsible molecule was solved using nuclear magnetic resonance and mass spectroscopy and was determined to be 2-hydroxy-4-((methylamino)(phenyl)methyl) cyclopentanone (HMCP), which was confirmed by chemical synthesis and NMR. The Confocal laser scanning microscopic analysis showed well-developed biofilm architecture of bacteria when treated with HMCP. The knowledge we obtained from this study will be useful for further researcher on the role of HMCP molecule in biofilm formation.

  6. On-nylon membrane detection of nucleic acid molecules by rolling circle amplification.

    Science.gov (United States)

    Xu, Xinhui; Zhang, Beibei; Gan, Ping; Wu, Jian; Dai, Wei; Zhang, Ling; Wang, Jinke

    2017-09-15

    Positively-charged nylon membrane (NM) is a general solid-phase support for nucleic acid detection due to its convenient immobilization of nucleic acid materials by direct electrostatic adherence and simple UV crosslinking. Rolling circle amplification (RCA) is a widely used isothermal DNA amplification technique for nucleic acid detection. Near-infrared fluorescence (NIRF) is a new fluorescence technique with high sensitivity due to low background. This study developed a simple method for detecting nucleic acid molecules by combining the advantages of NM, RCA and NIRF, named NIRF-based solid phase RCA on nylon membrane (NM-NIRF-sRCA). The detection system of this method only need two kinds of nucleic acid molecules: target-specific probes with a RCA primer (P) at their 3' end and a rolling circle (RC). The detection procedure consists of four steps: (1) immobilizing detected nucleic acids on NM by UV crosslinking; (2) hybridizing NM with specific probes and RC; (3) amplifying by a RCA reaction containing biotin-dUTP; (4) incubating NM with NIRF-labeled streptavidin and imaging with a NIRF imager. The method was fully testified by detecting oligonucleotides, L1 fragments of various HPV subtypes cloned in plasmid, and E.coli genomic DNA. This study thus provides a new facile method for detecting nucleic acid molecules. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. High sensitivity fluorescent single particle and single molecule detection apparatus and method

    Science.gov (United States)

    Mathies, Richard A.; Peck, Konan; Stryer, Lubert

    1990-01-01

    Apparatus is described for ultrasensitive detection of single fluorescent particles down to the single fluorescent molecule limit in a fluid or on a substrate comprising means for illuminating a predetermined volume of the fluid or area of the substrate whereby to emit light including background light from the fluid and burst of photons from particles residing in the area. The photon burst is detected in real time to generate output representative signal. The signal is received and the burst of energy from the fluorescent particles is distinguished from the background energy to provide an indication of the number, location or concentration of the particles or molecules.

  8. Outlier Detection with Space Transformation and Spectral Analysis

    DEFF Research Database (Denmark)

    Dang, Xuan-Hong; Micenková, Barbora; Assent, Ira

    2013-01-01

    Detecting a small number of outliers from a set of data observations is always challenging. In this paper, we present an approach that exploits space transformation and uses spectral analysis in the newly transformed space for outlier detection. Unlike most existing techniques in the literature w...

  9. Extensive survey of molecules related to wood formation and gravity for space agriculture.

    Science.gov (United States)

    Motohashi, Kyohei; Tomita-Yokotani, Kaori; Baba, Keiichi; Furukawa, Jun; Sato, Seigo; Suzuki, Toshisada; Hashimoto, Hirofumi; Yamashita, Masamichi; Japanese Space Tree Working Group

    Most, if not all, terrestrial subjects are under the influence of gravity. Since the gravitational force is proportional to the mass of subject, gravity is dominant for larger masses. The response of a plant against gravity is not an exception in this respect even it shows rather complicated features. For the angiosperm tree, its shape is determined by the forming tension wood, which induces more tensile stress in the xylem than in the normal wood. The mechanism of tension wood formation and its relevance to gravity have been extensively studied. Gibberellin is known to be responsible for this phenomenon in angiosperm tree, for example, the Japanese cherry tree, Prunus jamasakura. However, full understanding of the mechanisms has not yet been clarified. For an extensive survey of molecules related to tension wood formation, we induced an artificial tension wood formation and examined the tension wood formation by microscopic observations with double-staining. This enables the screening of really functional molecules in the space environment for future space agriculture. We demonstrated that Prunus incise is suitable for this research as a test material based on several reasons. We focused our attention in the region of the branch, i.e., the CosmoTree in CosmoBon, and established an experimental system to analyze the real functional factors of the tension wood. This study might ensure wood formation in a space environment and use woody plants as a material for space development. ("CosmoBon" is the Bonsai small tree for our space experiments. "CosmoTree" is a small branch/tree.)

  10. Space Object Detection in Video Satellite Images Using Motion Information

    Directory of Open Access Journals (Sweden)

    Xueyang Zhang

    2017-01-01

    Full Text Available Compared to ground-based observation, space-based observation is an effective approach to catalog and monitor increasing space objects. In this paper, space object detection in a video satellite image with star image background is studied. A new detection algorithm using motion information is proposed, which includes not only the known satellite attitude motion information but also the unknown object motion information. The effect of satellite attitude motion on an image is analyzed quantitatively, which can be decomposed into translation and rotation. Considering the continuity of object motion and brightness change, variable thresholding based on local image properties and detection of the previous frame is used to segment a single-frame image. Then, the algorithm uses the correlation of object motion in multiframe and satellite attitude motion information to detect the object. Experimental results with a video image from the Tiantuo-2 satellite show that this algorithm provides a good way for space object detection.

  11. Detecting and characterizing N-acyl-homoserine lactone signal molecules by thin-layer chromatography

    Science.gov (United States)

    Shaw, Paul D.; Ping, Gao; Daly, Sean L.; Cha, Chung; Cronan, John E.; Rinehart, Kenneth L.; Farrand, Stephen K.

    1997-01-01

    Many Gram-negative bacteria regulate gene expression in response to their population size by sensing the level of acyl-homoserine lactone signal molecules which they produce and liberate to the environment. We have developed an assay for these signals that couples separation by thin-layer chromatography with detection using Agrobacterium tumefaciens harboring lacZ fused to a gene that is regulated by autoinduction. With the exception of N-butanoyl-l-homoserine lactone, the reporter detected acyl-homoserine lactones with 3-oxo-, 3-hydroxy-, and 3-unsubstituted side chains of all lengths tested. The intensity of the response was proportional to the amount of the signal molecule chromatographed. Each of the 3-oxo- and the 3-unsubstituted derivatives migrated with a unique mobility. Using the assay, we showed that some bacteria produce as many as five detectable signal molecules. Structures could be assigned tentatively on the basis of mobility and spot shape. The dominant species produced by Pseudomonas syringae pv. tabaci chromatographed with the properties of N-(3-oxohexanoyl)-l-homoserine lactone, a structure that was confirmed by mass spectrometry. An isolate of Pseudomonas fluorescens produced five detectable species, three of which had novel chromatographic properties. These were identified as the 3-hydroxy- forms of N-hexanoyl-, N-octanoyl-, and N-decanoyl-l-homoserine lactone. The assay can be used to screen cultures of bacteria for acyl-homoserine lactones, for quantifying the amounts of these molecules produced, and as an analytical and preparative aid in determining the structures of these signal molecules. PMID:9177164

  12. Thermal Reactivity Of Organic Molecules With Perchlorates And The Detection Of Organics In Mars Samples With SAM Onboard Curiosity Rover

    Science.gov (United States)

    Szopa, C.; Millan, M.; Buch, A.; Freissinet, C.; Guzman, M.; Glavin, D. P.; Mahaffy, P. R.; Navarro-Gonzalez, R.

    2017-12-01

    The search for organic molecules at the Mars surface is a key objective to assess the potential for habitability of the planet and to find biomarkers. Both the past Viking landers and the Curiosity rover of today carry onboard instruments based on gas chromatography coupled to mass spectrometry with the aim to analyze the content of organics present in soil or rock samples. These instruments analyze the volatile compounds released from the samples submitted to thermal or chemical treatments. Even though these sample preparation processes are commonly used on Earth for their efficient extraction of organic materials from mineral matrixes, the presence of oxychlorines recently discovered in the Mars soil [1, 2] makes the process for space applications more complex and the results more difficult to interpret. Indeed, the release of volatile inorganic reactive molecules from oxychlorines during the sample heating process induces reactions of chlorination and oxidation of the organic molecules. For this reason, in an effort to contribute to the interpretation of the results obtained with the Viking/GCMS, and the MSL/SAM experiment our team currently operates on Mars, we started to study systematically the thermal reactivity of a series of organic molecules, of interest for Mars and life purposes, mixed with oxychlorines either detected or potentially present in the soil of Mars [3]. In this presentation, we will mainly focus on two sets of results that were obtained while studying the reactivity of calcium perchlorates with polyaromatic hydrocarbons, amino acids and carboxylic acids under pyrolytic conditions similar to those used in the SAM experiment. First of all, we will show the dependence of reactivity on the temperature of sublimation and decomposition of the individual components in the mixture and, secondly, we will discuss the detection of aromatic chlorinated species by SAM in samples collected at the Cumberland site from the results obtained in this study

  13. Single-molecule detection of dihydroazulene photo-thermal reaction using break junction technique

    Science.gov (United States)

    Huang, Cancan; Jevric, Martyn; Borges, Anders; Olsen, Stine T.; Hamill, Joseph M.; Zheng, Jue-Ting; Yang, Yang; Rudnev, Alexander; Baghernejad, Masoud; Broekmann, Peter; Petersen, Anne Ugleholdt; Wandlowski, Thomas; Mikkelsen, Kurt V.; Solomon, Gemma C.; Brøndsted Nielsen, Mogens; Hong, Wenjing

    2017-05-01

    Charge transport by tunnelling is one of the most ubiquitous elementary processes in nature. Small structural changes in a molecular junction can lead to significant difference in the single-molecule electronic properties, offering a tremendous opportunity to examine a reaction on the single-molecule scale by monitoring the conductance changes. Here, we explore the potential of the single-molecule break junction technique in the detection of photo-thermal reaction processes of a photochromic dihydroazulene/vinylheptafulvene system. Statistical analysis of the break junction experiments provides a quantitative approach for probing the reaction kinetics and reversibility, including the occurrence of isomerization during the reaction. The product ratios observed when switching the system in the junction does not follow those observed in solution studies (both experiment and theory), suggesting that the junction environment was perturbing the process significantly. This study opens the possibility of using nano-structured environments like molecular junctions to tailor product ratios in chemical reactions.

  14. Single-molecule detection of dihydroazulene photo-thermal reaction using break junction technique

    DEFF Research Database (Denmark)

    Huang, Cancan; Jevric, Martyn; Borges, Anders Christian

    2017-01-01

    a quantitative approach for probing the reaction kinetics and reversibility, including the occurrence of isomerization during the reaction. The product ratios observed when switching the system in the junction does not follow those observed in solution studies (both experiment and theory), suggesting......Charge transport by tunnelling is one of the most ubiquitous elementary processes in nature. Small structural changes in a molecular junction can lead to significant difference in the single-molecule electronic properties, offering a tremendous opportunity to examine a reaction on the single......-molecule scale by monitoring the conductance changes. Here, we explore the potential of the single-molecule break junction technique in the detection of photo-thermal reaction processes of a photochromic dihydroazulene/vinylheptafulvene system. Statistical analysis of the break junction experiments provides...

  15. Spins of adsorbed molecules investigated by the detection of Kondo resonance

    Science.gov (United States)

    Komeda, Tadahiro

    2014-12-01

    Surface magnetism has been one of the platforms to explore the magnetism in low dimensions. It is also a key component for the development of quantum information processes, which utilizes the spin degree of freedom. The Kondo resonance is a phenomenon that is caused by an interaction between an isolated spin and conduction electrons. First observed in the 1930s as an anomalous increase in the low-temperature resistance of metals embedded with magnetic atoms, the Kondo physics mainly studied the effects of bulk magnetic impurities in the resistivity. In the last 15 years it has undergone a revival by a scanning tunneling microscope (STM) which enables the measurement of the Kondo resonance at surfaces using an atomic scale point contact. The detection of the Kondo resonance can be a powerful tool to explore surface magnetism. In this article, I review recent studies of the surface spin of adsorbed molecules by the detection of the Kondo resonance. Researches on metal phthalocyanine (MPc) and porphyrin molecules will be examined. In addition, the Kondo resonance for double-decker lanthanoide Pc molecules will be discussed. Some of the double-decker Pc molecules show single-molecule magnet (SMM) behavior, which attracts attention as a material for electronic devices. For both classes, the ligand plays a crucial role in determining the parameters of the Kondo resonance, such as the Kondo temperature and the change of the shape from peak to Fano-dip. In addition, the spin in delocalized molecular orbital forms the Kondo resonance, which shows significant differences from the Kondo resonance formed by the metal spins. Since molecular orbital can be tuned in a flexible manner by the design of the molecule, the Kondo resonance formed by delocalized molecular orbital might expand the knowledge of this field.

  16. Tools for Detecting Causality in Space Systems

    Science.gov (United States)

    Johnson, J.; Wing, S.

    2017-12-01

    Complex systems such as the solar and magnetospheric envivonment often exhibit patterns of behavior that suggest underlying organizing principles. Causality is a key organizing principle that is particularly difficult to establish in strongly coupled nonlinear systems, but essential for understanding and modeling the behavior of systems. While traditional methods of time-series analysis can identify linear correlations, they do not adequately quantify the distinction between causal and coincidental dependence. We discuss tools for detecting causality including: granger causality, transfer entropy, conditional redundancy, and convergent cross maps. The tools are illustrated by applications to magnetospheric and solar physics including radiation belt, Dst (a magnetospheric state variable), substorm, and solar cycle dynamics.

  17. Marangoni Convection Assisted Single Molecule Detection with Nanojet Surface Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Chang, Te-Wei; Wang, Xinhao; Mahigir, Amirreza; Veronis, Georgios; Liu, Gang Logan; Gartia, Manas Ranjan

    2017-08-25

    Many single-molecule (SM) label-free techniques such as scanning probe microscopies (SPM) and magnetic force spectroscopies (MFS) provide high resolution surface topography information, but lack chemical information. Typical surface enhanced Raman spectroscopy (SERS) systems provide chemical information on the analytes, but lack spatial resolution. In addition, a challenge in SERS sensors is to bring analytes into the so-called "hot spots" (locations where the enhancement of electromagnetic field amplitude is larger than 10 3 ). Previously described methods of fluid transport around hot spots like thermophoresis, thermodiffusion/Soret effect, and electrothermoplasmonic flow are either too weak or detrimental in bringing new molecules to hot spots. Herein, we combined the resonant plasmonic enhancement and photonic nanojet enhancemnet of local electric field on nonplanar SERS structures, to construct a stable, high-resolution, and below diffraction limit platform for single molecule label-free detection. In addition, we utilize Marangoni convection (mass transfer due to surface tension gradient) to bring new analytes into the hotspot. An enhancement factor of ∼3.6 × 10 10 was obtained in the proposed system. Rhodamine-6G (R6G) detection of up to a concentration of 10 -12 M, an improvement of two orders of magnitude, was achieved using the nanojet effect. The proposed system could provide a simple, high throughput SERS system for single molecule analysis at high spatial resolution.

  18. Nanoantenna harmonic sensor: theoretical analysis of contactless detection of molecules with light

    KAUST Repository

    Farhat, Mohamed

    2015-09-25

    The nonlinear harmonic sensor is a popular wireless sensor and radiofrequency identification (RFID) technique, which allows high-performance sensing in a severe interference/clutter background by transmitting a radio wave and detecting its modulated higher-order harmonics. Here we introduce the concept and design of optical harmonic tags based on nonlinear nanoantennas that can contactlessly detect electronic (e.g. electron affinity) and optical (e.g. relative permittivity) characteristics of molecules. By using a dual-resonance gold-molecule–silver nanodipole antenna within the quantum mechanical realm, the spectral form of the second-harmonic scattering can sensitively reveal the physical properties of molecules, paving a new route towards optical molecular sensors and optical identification (OPID) of biological, genetic, and medical events for the \\'Internet of Nano-Things\\'.

  19. Blu-ray based optomagnetic aptasensor for detection of small molecules

    DEFF Research Database (Denmark)

    Yang, Jaeyoung; Donolato, Marco; Pinto, Alessandro

    2016-01-01

    the hydrodynamic size distribution of MNPs and their clusters. A commercial Blu-ray optical pickup unit is used for optical signal acquisition, which enables the establishment of a low-cost and miniaturized biosensing platform. Experimental results show that the degree of MNP clustering correlates well......This paper describes an aptamer-based optomagnetic biosensor for detection of a small molecule based on target binding-induced inhibition of magnetic nanoparticle (MNP) clustering. For the detection of a target small molecule, two mutually exclusive binding reactions (aptamer-target binding...... and aptamer-DNA linker hybridization) are designed. An aptamer specific to the target and a DNA linker complementary to a part of the aptamer sequence are immobilized onto separate MNPs. Hybridization of the DNA linker and the aptamer induces formation of MNP clusters. The target-to-aptamer binding on MNPs...

  20. Nanoantenna harmonic sensor: theoretical analysis of contactless detection of molecules with light

    International Nuclear Information System (INIS)

    Farhat, Mohamed; Cheng, Mark M C; Chen, Pai-Yen; Le, Khai Q

    2015-01-01

    The nonlinear harmonic sensor is a popular wireless sensor and radiofrequency identification (RFID) technique, which allows high-performance sensing in a severe interference/clutter background by transmitting a radio wave and detecting its modulated higher-order harmonics. Here we introduce the concept and design of optical harmonic tags based on nonlinear nanoantennas that can contactlessly detect electronic (e.g. electron affinity) and optical (e.g. relative permittivity) characteristics of molecules. By using a dual-resonance gold-molecule–silver nanodipole antenna within the quantum mechanical realm, the spectral form of the second-harmonic scattering can sensitively reveal the physical properties of molecules, paving a new route towards optical molecular sensors and optical identification (OPID) of biological, genetic, and medical events for the ‘Internet of Nano-Things’. (paper)

  1. Experimental Detection of Branching at a Conical Intersection in a Highly Fluorescent Molecule.

    Science.gov (United States)

    Brazard, Johanna; Bizimana, Laurie A; Gellen, Tobias; Carbery, William P; Turner, Daniel B

    2016-01-07

    Conical intersections are molecular configurations at which adiabatic potential-energy surfaces touch. They are predicted to be ubiquitous, yet condensed-phase experiments have focused on the few systems with clear spectroscopic signatures of negligible fluorescence, high photoactivity, or femtosecond electronic kinetics. Although rare, these signatures have become diagnostic for conical intersections. Here we detect a coherent surface-crossing event nearly two picoseconds after optical excitation in a highly fluorescent molecule that has no photoactivity and nanosecond electronic kinetics. Time-frequency analysis of high-sensitivity measurements acquired using sub-8 fs pulses reveals phase shifts of the signal due to branching of the wavepacket through a conical intersection. The time-frequency analysis methodology demonstrated here on a model compound will enable studies of conical intersections in molecules that do not exhibit their diagnostic signatures. Improving the ability to detect conical intersections will enrich the understanding of their mechanistic role in molecular photochemistry.

  2. Highly sensitive immunoassay of protein molecules based on single nanoparticle fluorescence detection in a nanowell

    Science.gov (United States)

    Han, Jin-Hee; Kim, Hee-Joo; Lakshmana, Sudheendra; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.

    2011-03-01

    A nanoarray based-single molecule detection system was developed for detecting proteins with extremely high sensitivity. The nanoarray was able to effectively trap nanoparticles conjugated with biological sample into nanowells by integrating with an electrophoretic particle entrapment system (EPES). The nanoarray/EPES is superior to other biosensor using immunoassays in terms of saving the amounts of biological solution and enhancing kinetics of antibody binding due to reduced steric hindrance from the neighboring biological molecules. The nanoarray patterned onto a layer of PMMA and LOL on conductive and transparent indium tin oxide (ITO)-glass slide by using e-beam lithography. The suspension of 500 nm-fluorescent (green emission)-carboxylated polystyrene (PS) particles coated with protein-A followed by BDE 47 polyclonal antibody was added to the chip that was connected to the positive voltage. The droplet was covered by another ITO-coated-glass slide and connected to a ground terminal. After trapping the particles into the nanowells, the solution of different concentrations of anti-rabbit- IgG labeled with Alexa 532 was added for an immunoassay. A single molecule detection system could quantify the anti-rabbit IgG down to atto-mole level by counting photons emitted from the fluorescent dye bound to a single nanoparticle in a nanowell.

  3. Highly sensitive, non-invasive detection of colorectal cancer mutations using single molecule, third generation sequencing

    Directory of Open Access Journals (Sweden)

    Giancarlo Russo

    2015-12-01

    We present the first study that applies the high read accuracy and depth of single molecule, real time, circular consensus sequencing (SMRT-CCS to the detection of mutations in stool DNA in order to provide a non-invasive, sensitive and accurate test for CRC. In stool DNA isolated from patients diagnosed with adenocarcinoma, we are able to detect mutations at frequencies below 0.5% with no false positives. This approach establishes a foundation for a non-invasive, highly sensitive assay to screen the population for CRC and the early stage adenomas that lead to CRC.

  4. Nanomaterial based electrochemical sensors for in vitro detection of small molecule metabolites.

    Science.gov (United States)

    Xiao, Fei; Wang, Lu; Duan, Hongwei

    2016-01-01

    Small molecule metabolites secreted by pathological processes can act as molecular biomarkers for clinical diagnosis. In vitro detection of the metabolites such as glucose and reactive oxygen species is of great significance for precise screening, monitoring and prognosis of metabolic disorders and relevant diseases such as cancer, and has been under intense research and development in clinical chemistry and molecular diagnostics. In this review, we summarize recent developments in nanomaterial based electrochemical (bio)sensors for in vitro detection of glucose and reactive oxygen species and the progress in utilizing lightweight and flexible electrodes and micro/nanoscale electrodes for flexible and miniaturized sensors. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Multiplexed profiling of secreted proteins for the detection of potential space biomarkers.

    Science.gov (United States)

    Dieriks, Birger; De Vos, Winnok H; Moreels, Marjan; Ghardi, Myriam; Hennekam, Raoul; Broers, Jos L V; Baatout, Sarah; van Oostveldt, Patrick

    2011-01-01

    Space travel exposes astronauts to a plethora of potentially detrimental conditions, such as cosmic radiation and microgravity. As both factors are hard to simulate on Earth, present knowledge remains limited. However, this knowledge is of vital importance, making space flight experiments a necessity for determining the biological effects and the underlying biochemical processes, especially when keeping future long-term interplanetary missions in mind. Instead of estimating the long-term effects, which usually implicate severe endpoints (e.g., cancer) and which are often difficult to attribute, research has shifted to finding representative biomarkers for rapid and sensitive detection of individual radiosensitivity. In this context, an appealing set of candidate markers is the group of secreted proteins, as they exert an intercellular signaling function and are easy to assess. We screened a subset of secreted proteins in cells exposed to space travel by means of multiplex bead array analysis. To determine the cell-specific signatures of the secreted molecules, we compared the conditioned medium of normal fibroblast cells to fibroblasts isolated from a patient with Hutchinson-Gilford Progeria syndrome, which are known to have a perturbed nuclear architecture and DNA damage response. Out of the 88 molecules screened, 20 showed a significant level increase or decrease, with a differential response to space conditions between the two cell types. Among the molecules that were retained, which may prove to be valuable biomarkers, are apolipoprotein C-III, plasminogen activator inhibitor type 1, β-2-microglobulin, ferritin, MMP-3, TIMP-1 and VEGF.

  6. Detection of molecules and cells using nuclear magnetic resonance with magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rümenapp, Christine, E-mail: ruemenapp@tum.de [Zentralinstitut für Medizintechnik (IMETUM), Technische Universität München, Garching (Germany); Gleich, Bernhard [Zentralinstitut für Medizintechnik (IMETUM), Technische Universität München, Garching (Germany); Mannherz, Hans Georg [Abteilung für Anatomie und Molekulare Embryologie, Ruhr Universität Bochum, Bochum (Germany); Haase, Axel [Zentralinstitut für Medizintechnik (IMETUM), Technische Universität München, Garching (Germany)

    2015-04-15

    For the detection of small molecules, proteins or even cells in vitro, functionalised magnetic nanoparticles and nuclear magnetic resonance measurements can be applied. In this work, magnetic nanoparticles with the size of 5–7 nm were functionalised with antibodies to detect two model systems of different sizes, the protein avidin and Saccharomyces cerevisiae as the model organism. The synthesised magnetic nanoparticles showed a narrow size distribution, which was determined using transmission electron microscopy and dynamic light scattering. The magnetic nanoparticles were functionalised with the according antibodies via EDC/NHS chemistry. The binding of the antigen to magnetic nanoparticles was detected through the change in the NMR T{sub 2} relaxation time at 0.5 T (≈21.7 MHz). In case of a specific binding the particles cluster and the T{sub 2} relaxation time of the sample changes. The detection limit in buffer for FITC-avidin was determined to be 1.35 nM and 10{sup 7} cells/ml for S. cerevisiae. For fluorescent microscopy the avidin molecules were labelled with FITC and for the detection of S. cerevisiae the magnetic nanoparticles were additionally functionalised with rhodamine. The binding of the particles to S. cerevisiae and the resulting clustering was also seen by transmission electron microscopy.

  7. Nanopore arrays in a silicon membrane for parallel single-molecule detection: DNA translocation.

    Science.gov (United States)

    Zhang, Miao; Schmidt, Torsten; Jemt, Anders; Sahlén, Pelin; Sychugov, Ilya; Lundeberg, Joakim; Linnros, Jan

    2015-08-07

    Optical nanopore sensing offers great potential in single-molecule detection, genotyping, or DNA sequencing for high-throughput applications. However, one of the bottle-necks for fluorophore-based biomolecule sensing is the lack of an optically optimized membrane with a large array of nanopores, which has large pore-to-pore distance, small variation in pore size and low background photoluminescence (PL). Here, we demonstrate parallel detection of single-fluorophore-labeled DNA strands (450 bps) translocating through an array of silicon nanopores that fulfills the above-mentioned requirements for optical sensing. The nanopore array was fabricated using electron beam lithography and anisotropic etching followed by electrochemical etching resulting in pore diameters down to ∼7 nm. The DNA translocation measurements were performed in a conventional wide-field microscope tailored for effective background PL control. The individual nanopore diameter was found to have a substantial effect on the translocation velocity, where smaller openings slow the translocation enough for the event to be clearly detectable in the fluorescence. Our results demonstrate that a uniform silicon nanopore array combined with wide-field optical detection is a promising alternative with which to realize massively-parallel single-molecule detection.

  8. Applications of a single-molecule detection in early disease diagnosis and enzymatic reaction study

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiangwei [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    Various single-molecule techniques were utilized for ultra-sensitive early diagnosis of viral DNA and antigen and basic mechanism study of enzymatic reactions. DNA of human papilloma virus (HPV) served as the screening target in a flow system. Alexa Fluor 532 (AF532) labeled single-stranded DNA probes were hybridized to the target HPV-16 DNA in solution. The individual hybridized molecules were imaged with an intensified charge-coupled device (ICCD) in two ways. In the single-color mode, target molecules were detected via fluorescence from hybridized probes only. This system could detect HPV-16 DNA in the presence of human genomic DNA down to 0.7 copy/cell and had a linear dynamic range of over 6 orders of magnitude. In the dual-color mode, fluorescence resonance energy transfer (FRET) was employed to achieve zero false-positive count. We also showed that DNA extracts from Pap test specimens did not interfere with the system. A surface-based method was used to improve the throughput of the flow system. HPV-16 DNA was hybridized to probes on a glass surface and detected with a total internal reflection fluorescence (TIRF) microscope. In the single-probe mode, the whole genome and target DNA were fluorescently labeled before hybridization, and the detection limit is similar to the flow system. In the dual-probe mode, a second probe was introduced. The linear dynamic range covers 1.44-7000 copies/cell, which is typical of early infection to near-cancer stages. The dual-probe method was tested with a crudely prepared sample. Even with reduced hybridization efficiency caused by the interference of cellular materials, we were still able to differentiate infected cells from healthy cells. Detection and quantification of viral antigen with a novel single-molecule immunosorbent assay (SMISA) was achieved. Antigen from human immunodeficiency virus type 1(HIV-1) was chosen to be the target in this study. The target was sandwiched between a monoclonal capture antibody and a

  9. Putting prions into focus: application of single molecule detection to the diagnosis of prion diseases.

    Science.gov (United States)

    Giese, A; Bieschke, J; Eigen, M; Kretzschmar, H A

    2000-01-01

    Prion diseases are characterized by the cerebral deposition of an aggregated pathological isoform of the prion protein (PrP(Sc)) which constitutes the principal component of the transmissible agent termed prion. In order to develop a highly sensitive method for the detection of PrP(Sc) aggregates in biological samples such as cerebrospinal fluid (CSF), we used a method based on Fluorescence Correlation Spectroscopy (FCS), a technique which allows detection of single fluorescently labeled molecules in solution. Within the FCS setup, fluorescent photons emitted by molecules passing an open volume element defined by the beam of an excitation laser focussed into a diffraction-limited spot are imaged confocally onto a single photon counting detector. Aggregates of PrP(Sc) could be labeled by co-aggregation of probe molecules such as monomeric recombinant PrP or PrP-specific antibodies tagged with a fluorescent dye. In addition to slow diffusion, labeled aggregates are characterized by high fluorescence intensity, which allows detection and quantification by analysis of fluorescence intensity distribution. To improve detection of rare target particles, the accessible volume element was increased by scanning for intensely fluorescent targets (SIFT). To further improve sensitivity and specificity, two different probes were used simultaneously in a two-color setup. In a diagnostic model system of CSF spiked with purified prion rods, dual-color SIFT was more sensitive than Western blot analysis. In addition, a PrP(Sc)-specific signal was also detected in a number of CSF samples derived from CJD patients but not in controls.

  10. Photofragment angular momentum polarization in the photolysis of symmetric top molecules: Production, detection, and rotational depolarization

    International Nuclear Information System (INIS)

    Shternin, Peter S.; Suits, Arthur G.; Vasyutinskii, Oleg S.

    2012-01-01

    Highlights: ► We describe the product polarization in the photolysis of symmetric top molecules. ► The polarization is written in terms of the anisotropy transforming coefficients. ► We studied the role of the angular momentum depolarization due to molecular rotation. ► We present a compact spherical tensor expression for the 2 + 1 REMPI absorption signal. - Abstract: We present the fully quantum mechanical distribution of the photofragment angular momentum polarization in the photolysis of an isotropic ensemble of symmetric top molecules. The distribution is written in terms of the recently established anisotropy transforming coefficients c k d q k K (P.S. Shternin, O.S. Vasyutinskii, Chem. Phys. 128 (2008) 194314) which contain all dynamical information on the photolysis dynamics and can be either determined from experiment, or calculated from theory. Explicit expressions for the coefficients c k d q k K for the case of photolysis of symmetric top molecules were obtained within the full quantum mechanical approach and then simplified using the quasiclassical approximation in the high-J limit. The role of the photofragment angular momentum depolarization due to molecular rotation was analyzed for three important particular cases: photolysis of diatomic molecules, photolysis of symmetric top molecules when the angular momentum polarization of atomic photofragments are detected, photolysis of symmetric top molecules when the angular momentum polarization of molecular photofragments are detected. The obtained rotation factors were compared with the results of previous studies. The paper also presents a compact spherical tensor expression for the 2 + 1 REMPI absorption signal which can be used for direct determination of the coefficients c k d q k K from experiment. A comparison was made between the anisotropy transforming coefficients c k d q k K and the polarization parameters A q K introduced very recently by (T.P. Rakitzis, A.J. Alexander, J. Chem. Phys

  11. Enhanced NMR signal detection of imino protons in RNA molecules containing 3' dangling nucleotides

    International Nuclear Information System (INIS)

    Amborski, Andrew N.; Johnson, Philip E.

    2008-01-01

    We present a method for improving the quality of nuclear magnetic resonance (NMR) spectra involving exchangeable protons near the base of the stem of RNA hairpin molecules. NMR spectra of five different RNA hairpins were compared. These hairpins consisted of a native RNA structure and four molecules each having different unpaired, or dangling, nucleotides at the 3' end. NMR experiments were acquired in water for each construct and the quality of the imino proton spectral regions were examined. The imino resonances near the base of the stem of the wild type RNA structure were not observed due to breathing motions. However, a significant increase in spectral quality for molecules with dangling 3' adenosine or guanosine nucleotides was observed, with imino protons detected in these constructs that were not observed in the wild type construct. A modest improvement in spectral quality was seen for the construct with a 3' unpaired uridine, whereas no significant improvement was observed for a 3' unpaired cytidine. This improvement in NMR spectral quality mirrors the increased thermodynamic stability observed for 3' unpaired nucleotides which is dependant on the stacking interactions of these nucleotides against the base of the stem. The use of a dangling 3' adenosine nucleotide represents an easy method to significantly improve the quality of NMR spectra of RNA molecules

  12. On the Detectability of CO Molecules in the Interstellar Medium via X-Ray Spectroscopy

    Science.gov (United States)

    Joachimi, Katerine; Gatuzz, Efrain; Garcia, Javier; Kallman, Timothy R.

    2016-01-01

    We present a study of the detectability of CO molecules in the Galactic interstellar medium using high-resolution X-ray spectra obtained with the XMM-Newton Reflection Grating Spectrometer. We analysed 10 bright low mass X-ray binaries (LMXBs) to study the CO contribution in their line of sights. A total of 25 observations were fitted with the ISMabs X-ray absorption model which includes photoabsorption cross-sections for Oi, Oii, Oiii and CO. We performed a Monte Carlo (MC) simulation analysis of the goodness of fit in order to estimate the significance of the CO detection. We determine that the statistical analysis prevents a significant detection of CO molecular X-ray absorption features, except for the lines of sight towards XTE J1718-330 and 4U 1636-53. In the case of XTE J1817-330, this is the first report of the presence of CO along its line of sight. Our results reinforce the conclusion that molecules have a minor contribution to the absorption features in the O K-edge spectral region. We estimate a CO column density lower limit to perform a significant detection with XMM-Newton of N(CO) greater than 6 x 10(exp 16) per sq cm for typical exposure times.

  13. Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules

    OpenAIRE

    El Sayed Shehata Nasr, Sameh

    2015-01-01

    [EN] Abstract The present PhD thesis entitled "Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules" is based on the application of supramolecular chemistry and material science principles for the development of optical chemosensors for anions and neutral molecules detection. The second chapter of this PhD thesis is devoted to the preparation of chemodosimeters for the chromo-fluorogenic detection of f...

  14. Topoisomerase I as a Biomarker: Detection of Activity at the Single Molecule Level

    DEFF Research Database (Denmark)

    Proszek, Joanna; Roy, Amit; Jakobsen, Ann-Katrine

    2014-01-01

    of hTopI cleavage-religation activity at the single molecule level, may be used to detect posttranslational enzymatic differences influencing CPT response. These differences cannot be detected by analysis of hTopI gene copy number, mRNA amount, or protein amount, and only become apparent upon measuring......Human topoisomerase I (hTopI) is an essential cellular enzyme. The enzyme is often upregulated in cancer cells, and it is a target for chemotherapeutic drugs of the camptothecin (CPT) family. Response to CPT-based treatment is dependent on hTopI activity, and reduction in activity, and mutations...... in hTopI have been reported to result in CPT resistance. Therefore, hTOPI gene copy number, mRNA level, protein amount, and enzyme activity have been studied to explain differences in cellular response to CPT. We show that Rolling Circle Enhanced Enzyme Activity Detection (REEAD), allowing measurement...

  15. Versatile single-molecule multi-color excitation and detection fluorescence setup for studying biomolecular dynamics

    KAUST Repository

    Sobhy, M. A.

    2011-11-07

    Single-molecule fluorescence imaging is at the forefront of tools applied to study biomolecular dynamics both in vitro and in vivo. The ability of the single-molecule fluorescence microscope to conduct simultaneous multi-color excitation and detection is a key experimental feature that is under continuous development. In this paper, we describe in detail the design and the construction of a sophisticated and versatile multi-color excitation and emission fluorescence instrument for studying biomolecular dynamics at the single-molecule level. The setup is novel, economical and compact, where two inverted microscopes share a laser combiner module with six individual laser sources that extend from 400 to 640 nm. Nonetheless, each microscope can independently and in a flexible manner select the combinations, sequences, and intensities of the excitation wavelengths. This high flexibility is achieved by the replacement of conventional mechanical shutters with acousto-optic tunable filter (AOTF). The use of AOTF provides major advancement by controlling the intensities, duration, and selection of up to eight different wavelengths with microsecond alternation time in a transparent and easy manner for the end user. To our knowledge this is the first time AOTF is applied to wide-field total internal reflection fluorescence (TIRF) microscopy even though it has been commonly used in multi-wavelength confocal microscopy. The laser outputs from the combiner module are coupled to the microscopes by two sets of four single-mode optic fibers in order to allow for the optimization of the TIRF angle for each wavelength independently. The emission is split into two or four spectral channels to allow for the simultaneous detection of up to four different fluorophores of wide selection and using many possible excitation and photoactivation schemes. We demonstrate the performance of this new setup by conducting two-color alternating excitation single-molecule fluorescence resonance energy

  16. Detection of tmRNA molecules on microarrays at low temperatures using helper oligonucleotides.

    Science.gov (United States)

    Kaplinski, Lauris; Scheler, Ott; Parkel, Sven; Palta, Priit; Toome, Kadri; Kurg, Ants; Remm, Maido

    2010-04-28

    The hybridization of synthetic Streptococcus pneumoniae tmRNA on a detection microarray is slow at 34 degrees C resulting in low signal intensities. We demonstrate that adding specific DNA helper oligonucleotides (chaperones) to the hybridization buffer increases the signal strength at a given temperature and thus makes the specific detection of Streptococcus pneumoniae tmRNA more sensitive. No loss of specificity was observed at low temperatures compared to hybridization at 46 degrees C. The effect of the chaperones can be explained by disruption of the strong secondary and tertiary structure of the target RNA by the selective hybridization of helper molecules. The amplification of the hybridization signal strength by chaperones is not necessarily local; we observed increased signal intensities in both local and distant regions of the target molecule. The sensitivity of the detection of tmRNA at low temperature can be increased by chaperone oligonucleotides. Due to the complexity of RNA secondary and tertiary structures the effect of any individual chaperone is currently not predictable.

  17. Detection of tmRNA molecules on microarrays at low temperatures using helper oligonucleotides

    Directory of Open Access Journals (Sweden)

    Palta Priit

    2010-04-01

    Full Text Available Abstract Background The hybridization of synthetic Streptococcus pneumoniae tmRNA on a detection microarray is slow at 34°C resulting in low signal intensities. Results We demonstrate that adding specific DNA helper oligonucleotides (chaperones to the hybridization buffer increases the signal strength at a given temperature and thus makes the specific detection of Streptococcus pneumoniae tmRNA more sensitive. No loss of specificity was observed at low temperatures compared to hybridization at 46°C. The effect of the chaperones can be explained by disruption of the strong secondary and tertiary structure of the target RNA by the selective hybridization of helper molecules. The amplification of the hybridization signal strength by chaperones is not necessarily local; we observed increased signal intensities in both local and distant regions of the target molecule. Conclusions The sensitivity of the detection of tmRNA at low temperature can be increased by chaperone oligonucleotides. Due to the complexity of RNA secondary and tertiary structures the effect of any individual chaperone is currently not predictable.

  18. Using Synthetic Nanopores for Single-Molecule Analyses: Detecting SNPs, Trapping DNA Molecules, and the Prospects for Sequencing DNA

    Science.gov (United States)

    Dimitrov, Valentin V.

    2009-01-01

    This work focuses on studying properties of DNA molecules and DNA-protein interactions using synthetic nanopores, and it examines the prospects of sequencing DNA using synthetic nanopores. We have developed a method for discriminating between alleles that uses a synthetic nanopore to measure the binding of a restriction enzyme to DNA. There exists…

  19. Numerical Study of Plasmonic Efficiency of Gold Nanostripes for Molecule Detection

    Directory of Open Access Journals (Sweden)

    Thomas Grosges

    2015-01-01

    Full Text Available In plasmonics, the accurate computation of the electromagnetic field enhancement is necessary in determining the amplitude and the spatial extension of the field around nanostructures. Here, the problem of the interaction between an electromagnetic excitation and gold nanostripes is solved. An optimization scheme, including an adaptive remeshing process with error estimator, is used to solve the problem through a finite element method. The variations of the electromagnetic field amplitude and the plasmonic active zones around nanostructures for molecule detection are studied in this paper taking into account the physical and geometrical parameters of the nanostripes. The evolution between the sizes and number of nanostripes is shown.

  20. In Situ Detection of Organic Molecules on the Martian Surface With the Mars Organic Molecule Analyzer (MOMA) on Exomars 2018

    Science.gov (United States)

    Li, Xiang; Brinckerhoff, William B.; Pinnick, Veronica T; van Amerom, Friso H. W.; Danell, Ryan M.; Arevalo, Ricardo D., Jr.; Getty, Stephanie; Mahaffy, Paul R.

    2015-01-01

    The Mars Organic Molecule Analyzer (MOMA) investigation on the 2018 ExoMars rover will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from radiative and oxidative degradation. The MOMA instrument is centered around a miniaturized linear ion trap (LIT) that facilitates two modes of operation: i) pyrolysisgas chromatography mass spectrometry (pyrGC-MS); and, ii) laser desorptionionization mass spectrometry (LDI-MS) at ambient Mars pressures. The LIT also enables the structural characterization of complex molecules via complementary analytical capabilities, such as multi-frequency waveforms (i.e., SWIFT) and tandem mass spectrometry (MSMS). When combined with the complement of instruments in the rovers Pasteur Payload, MOMA has the potential to reveal the presence of a wide range of organics preserved in a variety of mineralogical environments, and to begin to understand the structural character and potential origin of those compounds.

  1. Label-Free, Single Molecule Resonant Cavity Detection: A Double-Blind Experimental Study

    Directory of Open Access Journals (Sweden)

    Maria V. Chistiakova

    2015-03-01

    Full Text Available Optical resonant cavity sensors are gaining increasing interest as a potential diagnostic method for a range of applications, including medical prognostics and environmental monitoring. However, the majority of detection demonstrations to date have involved identifying a “known” analyte, and the more rigorous double-blind experiment, in which the experimenter must identify unknown solutions, has yet to be performed. This scenario is more representative of a real-world situation. Therefore, before these devices can truly transition, it is necessary to demonstrate this level of robustness. By combining a recently developed surface chemistry with integrated silica optical sensors, we have performed a double-blind experiment to identify four unknown solutions. The four unknown solutions represented a subset or complete set of four known solutions; as such, there were 256 possible combinations. Based on the single molecule detection signal, we correctly identified all solutions. In addition, as part of this work, we developed noise reduction algorithms.

  2. Probing non polar interstellar molecules through their protonated form: Detection of protonated cyanogen (NCCNH+).

    Science.gov (United States)

    Agúndez, M; Cernicharo, J; de Vicente, P; Marcelino, N; Roueff, E; Fuente, A; Gerin, M; Guélin, M; Albo, C; Barcia, A; Barbas, L; Bolaño, R; Colomer, F; Diez, M C; Gallego, J D; Gómez-González, J; López-Fernández, I; López-Fernández, J A; López-Pérez, J A; Malo, I; Serna, J M; Tercero, F

    2015-07-01

    Cyanogen (NCCN) is the simplest member of the series of dicyanopolyynes. It has been hypothesized that this family of molecules can be important constituents of interstellar and circumstellar media, although the lack of a permanent electric dipole moment prevents its detection through radioastronomical techniques. Here we present the first solid evidence of the presence of cyanogen in interstellar clouds through the detection of its protonated form toward the cold dark clouds TMC-1 and L483. Protonated cyanogen (NCCNH + ) has been identified through the J = 5 - 4 and J = 10 - 9 rotational transitions using the 40m radiotelescope of Yebes and the IRAM 30m telescope. We derive beam averaged column densities for NCCNH + of (8.6 ± 4.4) × 10 10 cm -2 in TMC-1 and (3.9 ± 1.8) × 10 10 cm -2 in L483, which translate to fairly low fractional abundances relative to H 2 , in the range (1-10) × 10 -12 . The chemistry of protonated molecules in dark clouds is discussed, and it is found that, in general terms, the abundance ratio between the protonated and non protonated forms of a molecule increases with increasing proton affinity. Our chemical model predicts an abundance ratio NCCNH + /NCCN of ~ 10 -4 , which implies that the abundance of cyanogen in dark clouds could be as high as (1-10) × 10 -8 relative to H 2 , i.e., comparable to that of other abundant nitriles such as HCN, HNC, and HC 3 N.

  3. Theoretical analysis of bimetallic nanorod dimer biosensors for label-free molecule detection

    Science.gov (United States)

    Das, Avijit; Talukder, Muhammad Anisuzzaman

    2018-02-01

    In this work, we theoretically analyze a gold (Au) core within silver (Ag) shell (Au@Ag) nanorod dimer biosensor for label-free molecule detection. The incident light on an Au@Ag nanorod strongly couples to localized surface plasmon modes, especially around the tip region. The field enhancement around the tip of a nanorod or between the tips of two longitudinally aligned nanorods as in a dimer can be exploited for sensitive detection of biomolecules. We derive analytical expressions for the interactions of an Au@Ag nanorod dimer with the incident light. We also study the detail dynamics of an Au@Ag nanorod dimer with the incident light computationally using finite difference time domain (FDTD) technique when core-shell ratio, relative position of the nanorods, and angle of incidence of light change. We find that the results obtained using the developed analytical model match well with that obtained using FDTD simulations. Additionally, we investigate the sensitivity of the Au@Ag nanorod dimer, i.e., shift in the resonance wavelength, when a target biomolecule such as lysozyme (Lys), human serum albumin (HSA), anti-biotin (Abn), human catalase (CAT), and human fibrinogen (Fb) protein molecules are attached to the tips of the nanorods.

  4. The Detection of Hot Cores and Complex Organic Molecules in the Large Magellanic Cloud

    Science.gov (United States)

    Sewiło, Marta; Indebetouw, Remy; Charnley, Steven B.; Zahorecz, Sarolta; Oliveira, Joana M.; van Loon, Jacco Th.; Ward, Jacob L.; Chen, C.-H. Rosie; Wiseman, Jennifer; Fukui, Yasuo; Kawamura, Akiko; Meixner, Margaret; Onishi, Toshikazu; Schilke, Peter

    2018-02-01

    We report the first extragalactic detection of the complex organic molecules (COMs) dimethyl ether (CH3OCH3) and methyl formate (CH3OCHO) with the Atacama Large Millimeter/submillimeter Array (ALMA). These COMs, together with their parent species methanol (CH3OH), were detected toward two 1.3 mm continuum sources in the N 113 star-forming region in the low-metallicity Large Magellanic Cloud (LMC). Rotational temperatures ({T}{rot}∼ 130 K) and total column densities ({N}{rot}∼ {10}16 cm‑2) have been calculated for each source based on multiple transitions of CH3OH. We present the ALMA molecular emission maps for COMs and measured abundances for all detected species. The physical and chemical properties of two sources with COMs detection, and the association with H2O and OH maser emission, indicate that they are hot cores. The fractional abundances of COMs scaled by a factor of 2.5 to account for the lower metallicity in the LMC are comparable to those found at the lower end of the range in Galactic hot cores. Our results have important implications for studies of organic chemistry at higher redshift.

  5. High Selective Gas Detection for small molecules based on Germanium selenide monolayer

    Science.gov (United States)

    Liu, Lian; Yang, Qun; Wang, Zeping; Ye, Huaiyu; Chen, Xianping; Fan, Xuejun; Zhang, Guoqi

    2018-03-01

    Predictive calculations based on density functional theory (DFT) are used here to study the electronic and optical properties of GeSe monolayer after adsorbing gas molecules (O2, NH3, SO2, H2, CO2, H2S, NO2, CH4, H2O, NO, CO). Our results reveal that for all the gas molecules considered, only NH3 is adsorbed on GeSe monolayer by physisorption. Whereas SO2 and NO2 are chemisorbed on GeSe monolayer with strong adsorption energies. In addition, the adsorption of O2, NO and NO2 distinctly enhances the optical absorbance and broaden the absorbance range of GeSe monolayer in visible light region. Also, it is found that the adsorption of H2S, NO and NH3 can reduce the work function of the GeSe monolayer. The results indicate that GeSe monolayer is not only a promising candidate for the sensing, capture, and storage of NH3, but also an anticipated disposable gas sensor or metal-free catalyst for detecting and catalyzing SO2 and NO2. Furthermore, it has excellent potential to be applied to optical sensors, solar cells, nanoelectronics or optoelectronics devices.

  6. A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

    Directory of Open Access Journals (Sweden)

    Stefanie Wolfram

    2014-10-01

    Full Text Available Molecular probes are widely used tools in chemical biology that allow tracing of bioactive metabolites and selective labeling of proteins and other biomacromolecules. A common structural motif for such probes consists of a reporter that can be attached by copper(I-catalyzed 1,2,3-triazole formation between terminal alkynes and azides to a reactive headgroup. Here we introduce the synthesis and application of the new thiazole-based, azide-tagged reporter 4-(3-azidopropoxy-5-(4-bromophenyl-2-(pyridin-2-ylthiazole for fluorescence, UV and mass spectrometry (MS detection. This small fluorescent reporter bears a bromine functionalization facilitating the automated data mining of electrospray ionization MS runs by monitoring for its characteristic isotope signature. We demonstrate the universal utility of the reporter for the detection of an alkyne-modified small molecule by LC–MS and for the visualization of a model protein by in-gel fluorescence. The novel probe advantageously compares with commercially available azide-modified fluorophores and a brominated one. The ease of synthesis, small size, stability, and the universal detection possibilities make it an ideal reporter for activity-based protein profiling and functional metabolic profiling.

  7. Aptamer/quantum dot-based simultaneous electrochemical detection of multiple small molecules

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Haixia [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Jiang Bingying [School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400040 (China); Xiang Yun, E-mail: yunatswu@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Zhang Yuyong; Chai Yaqin [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Ruo, E-mail: yuanruo@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2011-03-04

    A novel strategy for 'signal on' and sensitive one-spot simultaneous detection of multiple small molecular analytes based on electrochemically encoded barcode quantum dot (QD) tags is described. The target analytes, adenosine triphosphate (ATP) and cocaine, respectively, are sandwiched between the corresponding set of surface-immobilized primary binding aptamers and the secondary binding aptamer/QD bioconjugates. The captured QDs yield distinct electrochemical signatures after acid dissolution, whose position and size reflect the identity and level, respectively, of the corresponding target analytes. Due to the inherent amplification feature of the QD labels and the 'signal on' detection scheme, as well as the sensitive monitoring of the metal ions released upon acid dissolution of the QD labels, low detection limits of 30 nM and 50 nM were obtained for ATP and cocaine, respectively, in our assays. Our multi-analyte sensing system also shows high specificity to target analytes and promising applicability to complex sample matrix, which makes the proposed assay protocol an attractive route for screening of small molecules in clinical diagnosis.

  8. Detection of Facial Features in Scale-Space

    Directory of Open Access Journals (Sweden)

    P. Hosten

    2007-01-01

    Full Text Available This paper presents a new approach to the detection of facial features. A scale adapted Harris Corner detector is used to find interest points in scale-space. These points are described by the SIFT descriptor. Thus invariance with respect to image scale, rotation and illumination is obtained. Applying a Karhunen-Loeve transform reduces the dimensionality of the feature space. In the training process these features are clustered by the k-means algorithm, followed by a cluster analysis to find the most distinctive clusters, which represent facial features in feature space. Finally, a classifier based on the nearest neighbor approach is used to decide whether the features obtained from the interest points are facial features or not. 

  9. Methods for Detection of Families of Molecules in the Interstellar Medium

    Science.gov (United States)

    Langston, Glen

    2014-06-01

    We present a high velocity resolution (0.04 km/sec) molecular line survey of the Taurus Molecular Cloud in the frequency range 39 to 48 GHz with NSF's Robert C. Byrd Green Bank telescope (GBT). The observing method and data reduction process are outlined. We describe the method of obtaining the calibrated, averaged spectral line data online. The RMS survey sensitivity was slightly different for each 200MHz frequency band, and ranged from 0.02 to 0.15 K (T_B) for the different bands. A large number of molecular lines are detected, most of which have previously been associated with already known interstellar molecules. We present a summary processes to combine a number of lines of molecular species in order to identify new species.

  10. Metal-Organic Frameworks for Resonant-Gravimetric Detection of Trace-Level Xylene Molecules.

    Science.gov (United States)

    Xu, Tao; Xu, Pengcheng; Zheng, Dan; Yu, Haitao; Li, Xinxin

    2016-12-20

    As one of typical VOCs, xylene is seriously harmful to human health. Nowadays, however, there is really lack of portable sensing method to directly detect environmental xylene that has chemical inertness. Especially when the concentration of xylene is lower than the human olfactory threshold of 470 ppb, people are indeed hard to be aware of and avoid this harmful vapor. Herein the metal-organic framework (MOF) of HKUST-1 is first explored for sensing to the nonpolar molecule of p-xylene. And the sensing mechanism is identified that is via host-guest interaction of MOF with xylene molecule. By loading MOFs on mass-gravimetric resonant-cantilevers, sensing experiments for four MOFs of MOF-5, HKUST-1, ZIF-8, and MOF-177 approve that HKUST-1 has the highest sensitivity to p-xylene. The resonant-gravimetric sensing experiments with our HKUST-1 based sensors have demonstrated that trace-level p-xylene of 400 ppb can be detected that is lower than the human olfactory threshold of 470 ppb. We analyze that the specificity of HKUST-1 to xylene comes from Cu 2+ -induced moderate Lewis acidity and the "like dissolves like" interaction of the benzene ring. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to elucidate the adsorbing/sensing mechanism of HKUST-1 to p-xylene, where p-xylene adsorbing induced blue-shift phenomenon is observed that confirms the sensing mechanism. Our study also indicates that the sensor shows good selectivity to various kinds of common interfering gases. And the long-term repeatability and stability of the sensing material are also approved for the usage/storage period of two months. This research approves that the MOF materials exhibit potential usages for high performance chemical sensors applications.

  11. Detection, Characterization, and Biological Effect of Quorum-Sensing Signaling Molecules in Peanut-Nodulating Bradyrhizobia

    Directory of Open Access Journals (Sweden)

    Walter Giordano

    2012-03-01

    Full Text Available Bacteria of the genus Bradyrhizobium are able to establish a symbiotic relationship with peanut (Arachis hypogaea root cells and to fix atmospheric nitrogen by converting it to nitrogenous compounds. Quorum sensing (QS is a cell-cell communication mechanism employed by a variety of bacterial species to coordinate behavior at a community level through regulation of gene expression. The QS process depends on bacterial production of various signaling molecules, among which the N-acylhomoserine lactones (AHLs are most commonly used by Gram-negative bacteria. Some previous reports have shown the production of QS signaling molecules by various rhizobia, but little is known regarding mechanisms of communication among peanut-nodulating strains. The aims of this study were to identify and characterize QS signals produced by peanut-nodulating bradyrhizobial strains and to evaluate their effects on processes related to cell interaction. Detection of AHLs in 53 rhizobial strains was performed using the biosensor strains Agrobacterium tumefaciens NTL4 (pZLR4 and Chromobacterium violaceum CV026 for AHLs with long and short acyl chains, respectively. None of the strains screened were found to produce AHLs with short acyl chains, but 14 strains produced AHLs with long acyl chains. These 14 AHL-producing strains were further studied by quantification of β-galactosidase activity levels (AHL-like inducer activity in NTL4 (pZLR4. Strains displaying moderate to high levels of AHL-like inducer activity were subjected to chemical identification of signaling molecules by high-performance liquid chromatography coupled to mass spectrometry (LC-MS/MS. For each AHL-producing strain, we found at least four different AHLs, corresponding to N-hexanoyl-DL-homoserine lactone (C6, N-(3-oxodecanoyl-L-homoserine lactone (3OC10, N-(3-oxododecanoyl-L-homoserine lactone (3OC12, and N-(3-oxotetradecanoyl-L-homoserine lactone (3OC14. Biological roles of 3OC10, 3OC12, and 3OC14 AHLs

  12. A magnetic nanoparticle-clustering biosensor for blu-ray based optical detection of small-molecules

    DEFF Research Database (Denmark)

    Yang, Jaeyoung; Donolato, Marco; Antunes, Paula Soares Martins

    2014-01-01

    -cost instruments limit the advancement of MNP-based assays. We report here a novel MNP-clustering small-molecule assay on an optical readout platform to overcome the limitations aforementioned with the following improvements. First, a facile MNP-clustering assay applicable to diverse small-molecules was realized......In magnetic nanoparticle (MNP)-clustering assays, a target molecule is bound to multiple receptors tethered onto MNPs, triggering MNP-clustering and leading to changes in the size of clusters. However, sandwich-type clustering requires multiple binding-sites on a target molecule, which is often...... unavailable for small-molecules. Furthermore, measuring magnetic properties as signals is not intrinsically selective regarding MNP-cluster size. Thus, the detection of few MNP-clusters is readily interfered by background signals from predominantly-existing single MNPs. Additionally, bulky and high...

  13. Analytical Study of Colour Spaces for Plant Pixel Detection

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar

    2018-02-01

    Full Text Available Segmentation of regions of interest is an important pre-processing step in many colour image analysis procedures. Similarly, segmentation of plant objects in digital images is an important preprocessing step for effective phenotyping by image analysis. In this paper, we present results of a statistical analysis to establish the respective abilities of different colour space representations to detect plant pixels and separate them from background pixels. Our hypothesis is that the colour space representation for which the separation of the distributions representing object and background pixels is maximized is the best for the detection of plant pixels. The two pixel classes are modelled by Gaussian Mixture Models (GMMs. In our statistical modelling we make no prior assumptions on the number of Gaussians employed. Instead, a constant bandwidth mean-shift filter is used to cluster the data with the number of clusters, and hence the number of Gaussians, being automatically determined. We have analysed the following representative colour spaces: R G B , r g b , H S V , Y c b c r and C I E - L a b . We have analysed the colour space features from a two-class variance ratio perspective and compared the results of our model with this metric. The dataset for our empirical study consisted of 378 digital images (and their manual segmentations of a variety of plant species: Arabidopsis, tobacco, wheat, and rye grass, imaged under different lighting conditions, in either indoor or outdoor environments, and with either controlled or uncontrolled backgrounds. We have found that the best segmentation of plants is found using H S V colour space. This is supported by measures of Earth Mover Distance (EMD of the GMM distributions of plant and background pixels.

  14. Detection of NASBA amplified bacterial tmRNA molecules on SLICSel designed microarray probes.

    Science.gov (United States)

    Scheler, Ott; Kaplinski, Lauris; Glynn, Barry; Palta, Priit; Parkel, Sven; Toome, Kadri; Maher, Majella; Barry, Thomas; Remm, Maido; Kurg, Ants

    2011-02-28

    We present a comprehensive technological solution for bacterial diagnostics using tmRNA as a marker molecule. A robust probe design algorithm for microbial detection microarray is implemented. The probes were evaluated for specificity and, combined with NASBA (Nucleic Acid Sequence Based Amplification) amplification, for sensitivity. We developed a new web-based program SLICSel for the design of hybridization probes, based on nearest-neighbor thermodynamic modeling. A SLICSel minimum binding energy difference criterion of 4 kcal/mol was sufficient to design of Streptococcus pneumoniae tmRNA specific microarray probes. With lower binding energy difference criteria, additional hybridization specificity tests on the microarray were needed to eliminate non-specific probes. Using SLICSel designed microarray probes and NASBA we were able to detect S. pneumoniae tmRNA from a series of total RNA dilutions equivalent to the RNA content of 0.1-10 CFU. The described technological solution and both its separate components SLICSel and NASBA-microarray technology independently are applicative for many different areas of microbial diagnostics.

  15. Detection of NASBA amplified bacterial tmRNA molecules on SLICSel designed microarray probes

    Directory of Open Access Journals (Sweden)

    Toome Kadri

    2011-02-01

    Full Text Available Abstract Background We present a comprehensive technological solution for bacterial diagnostics using tmRNA as a marker molecule. A robust probe design algorithm for microbial detection microarray is implemented. The probes were evaluated for specificity and, combined with NASBA (Nucleic Acid Sequence Based Amplification amplification, for sensitivity. Results We developed a new web-based program SLICSel for the design of hybridization probes, based on nearest-neighbor thermodynamic modeling. A SLICSel minimum binding energy difference criterion of 4 kcal/mol was sufficient to design of Streptococcus pneumoniae tmRNA specific microarray probes. With lower binding energy difference criteria, additional hybridization specificity tests on the microarray were needed to eliminate non-specific probes. Using SLICSel designed microarray probes and NASBA we were able to detect S. pneumoniae tmRNA from a series of total RNA dilutions equivalent to the RNA content of 0.1-10 CFU. Conclusions The described technological solution and both its separate components SLICSel and NASBA-microarray technology independently are applicative for many different areas of microbial diagnostics.

  16. Detection of NASBA amplified bacterial tmRNA molecules on SLICSel designed microarray probes

    LENUS (Irish Health Repository)

    Scheler, Ott

    2011-02-28

    Abstract Background We present a comprehensive technological solution for bacterial diagnostics using tmRNA as a marker molecule. A robust probe design algorithm for microbial detection microarray is implemented. The probes were evaluated for specificity and, combined with NASBA (Nucleic Acid Sequence Based Amplification) amplification, for sensitivity. Results We developed a new web-based program SLICSel for the design of hybridization probes, based on nearest-neighbor thermodynamic modeling. A SLICSel minimum binding energy difference criterion of 4 kcal\\/mol was sufficient to design of Streptococcus pneumoniae tmRNA specific microarray probes. With lower binding energy difference criteria, additional hybridization specificity tests on the microarray were needed to eliminate non-specific probes. Using SLICSel designed microarray probes and NASBA we were able to detect S. pneumoniae tmRNA from a series of total RNA dilutions equivalent to the RNA content of 0.1-10 CFU. Conclusions The described technological solution and both its separate components SLICSel and NASBA-microarray technology independently are applicative for many different areas of microbial diagnostics.

  17. Single Molecule Arrays for ultra-sensitive detection of rat cytokines in serum.

    Science.gov (United States)

    Cohen, Limor; Xie, Liangxia; Xylas, Mark E; Walt, David R

    2018-01-01

    Rats are used as animal models for many human diseases. Cytokines can serve as biomarkers indicative of these diseases or disease states. Techniques for measuring cytokine expression levels often do not provide the sensitivity needed to measure these biomarkers in biological fluids because the concentrations of many cytokines are below the detection limits of conventional methods. In this paper, we present ultra-sensitive digital immunoassays using Single Molecule Arrays (Simoa) for seven rat cytokines: TNF-α, IL-10, IL-17F, GM-CSF, IFN-γ, IL-4, and IL-1α. These ultra-sensitive immunoassays have limits of detection (LODs) in the femtomolar range and provide the ability to measure rat cytokines in serum below the LODs of conventional immunoassays. We also measured these cytokines in healthy rat serum to obtain baseline levels. The ability to measure cytokines present at low concentrations in rat serum will facilitate future studies of disease using rats as animal models. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. [Detecting cardiac arrhythmias based on phase space analysis].

    Science.gov (United States)

    Sun, Rongrong; Wang, Yuanyuan; Yang, Su; Fang, Zuxiang

    2008-08-01

    It is important for cardiac therapy devices such as the automated external defibrillator to discriminate different cardiac disorders based on Electrocardiogram analysis. A phase space analysis based algorithm is proposed to detect cardiac arrhythmias effectively. Firstly, the phase space of the signal is reconstructed. Then from the viewpoint of geometry and information theory, the distribution entropy of the point density in the two-dimensional reconstructed phase space is calculated as the features in the further classification. Finally the nearest-neighbour method based on Mahalanobis distance is used to classify the sinus rhythm (SR), supraventricular tachyarrhythmia (SVTA), atrial flutter (AFL) and atrial fibrillation (AF). To evaluate the sensitivity, specificity and accuracy of this proposed method in the cardiac arrhythmias classification, the MIT-BIH arrhythmias database and the canine endocardial database are studied respectively. Experiment results demonstrate that the proposed method can detect SR, SVTA, AFL and AF signals rapidly and accurately with the simple computation. It promises to find application in automated devices for cardiac arrhythmias therapy.

  19. Detection of DNA damage by space radiation in human fibroblasts flown on the International Space Station

    Science.gov (United States)

    Lu, Tao; Zhang, Ye; Wong, Michael; Feiveson, Alan; Gaza, Ramona; Stoffle, Nicholas; Wang, Huichen; Wilson, Bobby; Rohde, Larry; Stodieck, Louis; Karouia, Fathi; Wu, Honglu

    2017-02-01

    Although charged particles in space have been detected with radiation detectors on board spacecraft since the discovery of the Van Allen Belts, reports on the effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation is challenging due to the low dose and low dose rate nature of the radiation environment, and due to the difficulty in distinguishing the radiation effects from microgravity and other space environmental factors. In astronauts, only a few changes, such as increased chromosome aberrations in their lymphocytes and early onset of cataracts, are attributed primarily to their exposure to space radiation. In this study, cultured human fibroblasts were flown on the International Space Station (ISS). Cells were kept at 37 °C in space for 14 days before being fixed for analysis of DNA damage with the γ-H2AX assay. The 3-dimensional γ-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed several foci that were larger and displayed a track pattern only in the Day 14 flight samples. To confirm that the foci data from the flight study was actually induced from space radiation exposure, cultured human fibroblasts were exposed to low dose rate γ rays at 37 °C. Cells exposed to chronic γ rays showed similar foci size distribution in comparison to the non-exposed controls. The cells were also exposed to low- and high-LET protons, and high-LET Fe ions on the ground. Our results suggest that in G1 human fibroblasts under the normal culture condition, only a small fraction of large size foci can be attributed to high-LET radiation in space.

  20. Gravitational Wave Detection by Interferometry (Ground and Space

    Directory of Open Access Journals (Sweden)

    Hough Jim

    2000-01-01

    Full Text Available Significant progress has been made in recent years on the development of gravitational wave detectors. Sources such as coalescing compact binary systems, low-mass X-ray binaries, stellar collapses and pulsars are all possible candidates for detection. The most promising design of gravitational wave detector uses test masses a long distance apart and freely suspended as pendulums on Earth or in drag-free craft in space. The main theme of this review is a discussion of the mechanical and optical principles used in the various long baseline systems being built around the world -- LIGO (USA, VIRGO (Italy/France, TAMA 300 (Japan and GEO 600 (Germany/UK -- and in LISA, a proposed space-borne interferometer.

  1. Detecting Darwinism from Molecules in the Enceladus Plumes, Jupiter's Moons, and Other Planetary Water Lagoons.

    Science.gov (United States)

    Benner, Steven A

    2017-09-01

    To the astrobiologist, Enceladus offers easy access to a potential subsurface biosphere via the intermediacy of a plume of water emerging directly into space. A direct question follows: If we were to collect a sample of this plume, what in that sample, through its presence or its absence, would suggest the presence and/or absence of life in this exotic locale? This question is, of course, relevant for life detection in any aqueous lagoon that we might be able to sample. This manuscript reviews physical chemical constraints that must be met by a genetic polymer for it to support Darwinism, a process believed to be required for a chemical system to generate properties that we value in biology. We propose that the most important of these is a repeating backbone charge; a Darwinian genetic biopolymer must be a "polyelectrolyte." Relevant to mission design, such biopolymers are especially easy to recover and concentrate from aqueous mixtures for detection, simply by washing the aqueous mixtures across a polycharged support. Several device architectures are described to ensure that, once captured, the biopolymer meets two other requirements for Darwinism, homochirality and a small building block "alphabet." This approach is compared and contrasted with alternative biomolecule detection approaches that seek homochirality and constrained alphabets in non-encoded biopolymers. This discussion is set within a model for the history of the terran biosphere, identifying points in that natural history where these alternative approaches would have failed to detect terran life. Key Words: Enceladus-Life detection-Europa-Icy moon-Biosignatures-Polyelectrolyte theory of the gene. Astrobiology 17, 840-851.

  2. An integrated system for optical and electrical detection of single molecules/particles inside a solid-state nanopore.

    Science.gov (United States)

    Shi, Xin; Gao, Rui; Ying, Yi-Lun; Si, Wei; Chen, Yunfei; Long, Yi-Tao

    2015-01-01

    Nanopore techniques have proven to be useful tools for single-molecule detection. The combination of optical detection and ionic current measurements enables a new possibility for the parallel readout of multiple nanopores without complex nanofluidics and embedded electrodes. In this study, we developed a new integrated system for the label-free optical and electrical detection of single molecules based on a metal-coated nanopore. The entire system, containing a dark-field microscopy system and an ultralow current detection system with high temporal resolution, was designed and fabricated. An Au-coated nanopore was used to generate the optical signal. Light scattering from a single Au-coated nanopore was measured under a dark-field microscope. A lab-built ultralow current detection system was designed for the correlated optical and electrical readout. This integrated system might provide more direct and detailed information on single analytes inside the nanopore compared with classical ionic current measurements.

  3. Fiber optic emerging technologies for detection of hydrogen in space applications

    Science.gov (United States)

    Kazemi, Alex A.

    2009-05-01

    Hydrogen detection in space application is very challenging; public acceptance of hydrogen fuel would require the integration of a reliable hydrogen safety sensor. For detecting leakage of cryogenic fluids in spaceport facilities, launch vehicle industry and aerospace agencies are currently relying heavily on the bulky mass spectrometers, which fill one or more equipment racks, and weigh several hundred kilograms. Optical hydrogen sensors are intrinsically safe since they produce no arc or spark in an explosive environment caused by the leakage of hydrogen. Safety remains a top priority since leakage of hydrogen in air during production, storage, transfer and distribution creates an explosive atmosphere for concentrations between 4% (v/v) - the lower explosive limit (LEL) and 74.5% (v/v) - the upper explosive limit (UEL) at room temperature and pressure. Being a very small molecule, hydrogen is prone to leakage through seals and micro-cracks. This paper describes the development of fiber optic emerging technologies for detection of hydrogen in space applications. These systems consisted of Micro Mirror, Fiber Bragg grating, Evanescent Optical Fiber and Colorimetric Technology. The paper would discuss the sensor design and performance data under field deployment conditions.

  4. Chemical polyglycosylation and nanolitre detection enables single-molecule recapitulation of bacterial sugar export

    Science.gov (United States)

    Kong, Lingbing; Almond, Andrew; Bayley, Hagan; Davis, Benjamin G.

    2016-05-01

    The outermost protective layer of both Gram-positive and Gram-negative bacteria is composed of bacterial capsular polysaccharides. Insights into the interactions between the capsular polysaccharide and its transporter and the mechanism of sugar export would not only increase our understanding of this key process, but would also help in the design of novel therapeutics to block capsular polysaccharide export. Here, we report a nanolitre detection system that makes use of the bilayer interface between two droplets, and we use this system to study single-molecule recapitulation of sugar export. A synthetic strategy of polyglycosylation based on tetrasaccharide monomers enables ready synthetic access to extended fragments of K30 oligosaccharides and polysaccharides. Examination of the interactions between the Escherichia coli sugar transporter Wza and very small amounts of fragments of the K30 capsular polysaccharide substrate reveal the translocation of smaller but not larger fragments. We also observe capture events that occur only on the intracellular side of Wza, which would complement coordinated feeding by adjunct biosynthetic machinery.

  5. Theoretical Investigation of Optical Detection and Recognition of Single Biological Molecules Using Coherent Dynamics of Exciton-Plasmon Coupling.

    Science.gov (United States)

    Sadeghi, S M; Hood, B; Patty, K D; Mao, C-B

    2013-08-20

    We use quantum coherence in a system consisting of one metallic nanorod and one semi-conductor quantum dot to investigate a plasmonic nanosensor capable of digital optical detection and recognition of single biological molecules. In such a sensor the adsorption of a specific molecule to the nanorod turns off the emission of the system when it interacts with an optical pulse having a certain intensity and temporal width. The proposed quantum sensors can count the number of molecules of the same type or differentiate between molecule types with digital optical signals that can be measured with high certainty. We show that these sensors are based on the ultrafast upheaval of coherent dynamics of the system and the removal of coherent blockage of energy transfer from the quantum dot to the nanorod once the adsorption process has occurred.

  6. Single molecule upconversion-linked immunosorbent assay with extended dynamic range for the sensitive detection of diagnostic biomarkers

    Czech Academy of Sciences Publication Activity Database

    Farka, Z.; Matthias, J. M.; Hlaváček, Antonín; Skládal, P.; Gorris, H H.

    2017-01-01

    Roč. 89, NOV (2017), s. 11825-11830 ISSN 0003-2700 R&D Projects: GA ČR(CZ) GBP206/12/G014 Institutional support: RVO:68081715 Keywords : photon upconversion * immunoassay * single molecule detection Subject RIV: CB - Analytical Chemistry , Separation OBOR OECD: Analytical chemistry Impact factor: 6.320, year: 2016

  7. Selective trace gas detection of complex molecules with a continuous wave optical parametric oscillator using a planar jet expansion

    NARCIS (Netherlands)

    Ngai, A.K.Y.; Persijn, S.T.; Harren, F.J.M.; Verbraak, H.; Linnartz, H.

    2007-01-01

    The authors present a trace gas detection method for complex molecules using continuous cavity ring-down spectroscopy in combination with a continuous wave optical parametric oscillator (tunability wavelength: 2.8-4.8 mu m; power: 1 W) sampling a supersonic planar jet expansion (nozzle dimension: 3

  8. Single molecule upconversion-linked immunosorbent assay with extended dynamic range for the sensitive detection of diagnostic biomarkers

    Czech Academy of Sciences Publication Activity Database

    Farka, Z.; Matthias, J. M.; Hlaváček, Antonín; Skládal, P.; Gorris, H H.

    2017-01-01

    Roč. 89, NOV (2017), s. 11825-11830 ISSN 0003-2700 R&D Projects: GA ČR(CZ) GBP206/12/G014 Institutional support: RVO:68081715 Keywords : photon upconversion * immunoassay * single molecule detection Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 6.320, year: 2016

  9. Automated Detection of Small Bodies by Space Based Observation

    Science.gov (United States)

    Bidstrup, P. R.; Grillmayer, G.; Andersen, A. C.; Haack, H.; Jorgensen, J. L.

    The number of known comets and asteroids is increasing every year. Up till now this number is including approximately 250,000 of the largest minor planets, as they are usually referred. These discoveries are due to the Earth-based observation which has intensified over the previous decades. Additionally larger telescopes and arrays of telescopes are being used for exploring our Solar System. It is believed that all near- Earth and Main-Belt asteroids of diameters above 10 to 30 km have been discovered, leaving these groups of objects as observationally complete. However, the cataloguing of smaller bodies is incomplete as only a very small fraction of the expected number has been discovered. It is estimated that approximately 1010 main belt asteroids in the size range 1 m to 1 km are too faint to be observed using Earth-based telescopes. In order to observe these small bodies, space-based search must be initiated to remove atmospheric disturbances and to minimize the distance to the asteroids and thereby minimising the requirement for long camera integration times. A new method of space-based detection of moving non-stellar objects is currently being developed utilising the Advanced Stellar Compass (ASC) built for spacecraft attitude determination by Ørsted, Danish Technical University. The ASC serves as a backbone technology in the project as it is capable of fully automated distinction of known and unknown celestial objects. By only processing objects of particular interest, i.e. moving objects, it will be possible to discover small bodies with a minimum of ground control, with the ultimate ambition of a fully automated space search probe. Currently, the ASC is being mounted on the Flying Laptop satellite of the Institute of Space Systems, Universität Stuttgart. It will, after a launch into a low Earth polar orbit in 2008, test the detection method with the ASC equipment that already had significant in-flight experience. A future use of the ASC based automated

  10. Homochirality in space – Selective enrichment of chiral molecules on chiral surfaces

    Directory of Open Access Journals (Sweden)

    Marloie G.

    2014-02-01

    $\\left\\{ {10\\,\\overline {10} } \\right\\}$ and the chiral molécule is lactic acid, HOCH(CH3COOH. In this theoretical work we rely on numerical simulations based on Density Functional Theory (DFT that proved efficient in the super-molecule and periodic approaches to this category of phenomena. In view of the different types of adsorption sites, a statistical treatment was necessary; it shows that (S-lactic acid is preferentially adsorbed with a selectivity of ~0.7 kcal/mol with respect to the (R isomer.

  11. Handling and Sensing of Single Enzyme Molecules: From Fluorescence Detection towards Nanoscale Electrical Measurements

    DEFF Research Database (Denmark)

    Mathwig, Klaus; Chi, Qijin; Lemay, Serge G.

    2016-01-01

    advances in all-electrical single enzyme studies with a focus on recent micro- and nanofluidic tools, which offer new ways of handling and studying small numbers of molecules or even single enzyme molecules. We particularly emphasize nanofluidic devices, which enable the integration of electrochemical...

  12. The Quest for Complex Molecules in Space. Searches for Cyanides Related to n-PROPYL Cyanide in SGR B2(N)

    Science.gov (United States)

    Müller, Holger S. P.; Schlemmer, S.; Belloche, A.; Menten, K. M.; Coutens, A.; Walters, A.; Grabow, J.-U.

    2011-06-01

    A molecular line survey was carried out with the IRAM 30 m telescope toward the prolific hot core Sgr B2(N) in order to explore its molecular complexity. The entire 3 mm range as well as selected regions at 2 and 1.3 mm were covered. Notable results include the detections of aminoacetonitrile, ethyl formate, n-propyl cyanide,^b and the singly substituted 13C isotopologs of vinyl cyanide. There exists a branched isomer of n-propyl cyanide: iso-propyl cyanide. A search for this isomer in our line survey required a laboratory spectroscopic investigation beforehand. Even though promising emission features have been found for this as well as other, related molecules, there are rather few uncontaminated lines. Overlap by other emission or some absorption features occurs frequently, and uncertainties about the position of the baseline also contribute to considering detections to be inconclusive. Nevertheless, the determination of upper limits or abundances among isomers and related molecules will help to constrain astrochemical pathways. We will present our results and discuss promising strategies to search for complex molecules in space. A. Belloche, K. M. Menten, C. Comito, H. S. P. Müller, P. Schilke, J. Ott, S. Thorwirth, C. Hieret, Astron. Astrophys. 482 (2008) 179. A. Belloche, R. T. Garrod, H. S. P. Müller, K. M. Menten, C. Comito, P. Schilke, Astron. Astrophys. 499 (2009), 215. H. S. P. Müller, A. Belloche, K. M. Menten, C. Comito, P. Schilke, J. Mol. Spectrosc. 251 (2008) 319. H. S. P. Müller, A. Coutens, A. Walters, J.-U. Grabow, S. Schlemmer, submitted to J. Mol. Spectrosc.

  13. Optical and Electrical Detection of Single Molecule Translocation through Carbon Nanotubes

    Science.gov (United States)

    Song, Weisi; Pang, Pei; He, Jin; Lindsay, Stuart

    2013-01-01

    Ion current through a single-walled carbon nanotube (SWCNT) was monitored at the same time as fluorescence was recorded from charged dye molecules translocating through the SWCNT. Fluorescence bursts generally follow ion-current peaks with a delay time consistent with diffusion from the end of the SWCNT to the fluorescence collection point. The fluorescence amplitude distribution of the bursts is consistent with single molecule signals. Thus each peak in the ion current flowing through the SWCNT is associated with the translocation of a single molecule. Ion current peaks (as opposed to blockades) were produced by both positively (Rhodamine 6G) and negatively (Alexa 546) charged molecules, showing that the charge filtering responsible for the current bursts is caused by the molecules themselves. PMID:23248975

  14. Histochemical detection of acetogenins and storage molecules in the endosperm of Annona macroprophyllata Donn Sm. seeds.

    Science.gov (United States)

    Laguna Hernández, G; Brechú-Franco, A E; De la Cruz-Chacón, I; González-Esquinca, A R

    2015-07-09

    Acetogenins (ACGs) are bioactive compounds with cytotoxic properties in different cell lines. They are antitumoural, antiparasitic, antimalarial, insecticidal, antimicrobial, antifungal and antibacterial. These secondary metabolites function in plant defence and are found in specific organelles and specific cells, thereby preventing toxicity to the plant itself and permitting site-specific defence. The aim of this work was to histochemically determine the in situ localisation of ACGs in the endosperm of Annona macroprophyllata seeds using Kedde's reagent. Additionally, the colocalisation of ACGs with other storage molecules was analysed. The seeds were analysed after 6 and 10 days of imbibition, when 1 or 2 cm of the radicle had emerged and metabolism was fully established. The seeds were then transversally cut in half at the midline and processed using different histological and histochemical techniques. Positive reactions with Kedde's reagent were only observed in fresh, unfixed sections that were preserved in water, and staining was found only in the large cells (the idioblasts) at the periphery of the endosperm. The ACGs' positive reaction with Sudan III corroborated their lipid nature. Paraffin sections stained with Naphthol Blue Black showed reactions in the endosperm parenchyma cells and stained the proteoplasts blue, indicating that they might correspond to storage sites for albumin-like proteins. Lugol's iodine, which is similar in chemical composition to Wagner's reagent, caused a golden brown reaction product in the cytoplasm of the idioblasts, which may indicate the presence of alkaloids. Based on these results, we propose that Kedde's reagent is an appropriate histochemical stain for detecting ACGs in situ in idioblasts and that idioblasts store ACGs and probably alkaloids. ACGs that are located in idioblasts found in restricted, peripheral areas of the endosperm could serve as a barrier that protects the seeds against insects and pathogen attack.

  15. Chromosomal Rainbows detect Oncogenic Rearrangements of Signaling Molecules in Thyroid Tumors

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Benjamin; Jossart, Gregg H.; Ito, Yuko; Greulich-Bode, Karin M.; Weier, Jingly F.; Munne, Santiago; Clark, Orlo H.; Weier, Heinz-Ulrich G.

    2010-08-19

    Altered signal transduction can be considered a hallmark of many solid tumors. In thyroid cancers the receptor tyrosine kinase (rtk) genes NTRK1 (Online Mendelian Inheritance in Man = OMIM *191315, also known as 'TRKA'), RET ('Rearranged during Transfection protooncogene', OMIM *164761) and MET (OMIM *164860) have been reported as activated, rearranged or overexpressed. In many cases, a combination of cytogenetic and molecular techniques allows elucidation of cellular changes that initiate tumor development and progression. While the mechanisms leading to overexpression of the rtk MET gene remain largely unknown, a variety of chromosomal rearrangements of the RET or NTKR1 gene could be demonstrated in thyroid cancer. Abnormal expressions in these tumors seem to follow a similar pattern: the rearrangement translocates the 3'-end of the rtk gene including the entire catalytic domain to an expressed gene leading to a chimeric RNA and protein with kinase activity. Our research was prompted by an increasing number of reports describing translocations involving ret and previously unknown translocation partners. We developed a high resolution technique based on fluorescence in situ hybridization (FISH) to allow rapid screening for cytogenetic rearrangements which complements conventional chromosome banding analysis. Our technique applies simultaneous hybridization of numerous probes labeled with different reporter molecules which are distributed along the target chromosome allowing the detection of cytogenetic changes at near megabase-pair (Mbp) resolution. Here, we report our results using a probe set specific for human chromosome 10, which is altered in a significant portion of human thyroid cancers (TC's). While rendering accurate information about the cytogenetic location of rearranged elements, our multi-locus, multi-color analysis was developed primarily to overcome limitations of whole chromosome painting (WCP) and chromosome banding

  16. Mechanochromic Fluorescent Probe Molecules for Damage Detection in Aerospace Polymers and Composites

    Science.gov (United States)

    Toivola, Ryan E.

    The detection of damage in aerospace composites can be improved by incorporation of mechanochromic fluorescent probe molecules into the polymers used in composite parts. This study focuses on a novel series of mechanochromic probes, AJNDE15 and AJNDE17, which are incorporated in structural epoxy resin DGEBA-DETA. Chapter 1 details the characterization of the DGEBA-DETA epoxy system used in this study. The important characteristics of DGEBA-DETA's response to mechanical loading will be discussed within the larger field of glassy amorphous polymer deformation. The mechanical, thermal, and chemical properties of DGEBA-DETA relevant to this work will be measured using standardized techniques and instrumentation. Chapters 2 and 3 focus on the mechanochromic probes AJNDE15 and AJNDE17 in the DGEBA-DETA system. Chapter 2 presents research designed to identify the mechanism through which the probes display mechanochromism. The possible mechanochromic mechanisms are introduced in a literature review. Research on these probes in DGEBA-DETA will be presented and discussed with respect to the possible mechanisms, and the mechanism that best fits the results will be identified as a mechanochemical reaction. Chapter 3 continues the analysis of the mechanochromism of the probes in DGEBA-DETA. The kinetics of the mechanochromic reaction will be studied and compared with the current understanding of glassy polymer deformation. Possible models for the molecular interactions responsible for mechanochromism in this system will be put forward. Research will be presented to evaluate the mechanochromism kinetics and for comparison with the behavior predicted by the models.

  17. Immunological detection of small organic molecules in the presence of perchlorates: relevance to the life marker chip and life detection on Mars.

    Science.gov (United States)

    Rix, Catherine S; Sims, Mark R; Cullen, David C

    2011-11-01

    The proposed ExoMars mission, due to launch in 2018, aims to look for evidence of extant and extinct life in martian rocks and regolith. Previous attempts to detect organic molecules of biological or abiotic origin on Mars have been unsuccessful, which may be attributable to destruction of these molecules by perchlorate salts during pyrolysis sample extraction techniques. Organic molecules can also be extracted and measured with solvent-based systems. The ExoMars payload includes the Life Marker Chip (LMC) instrument, capable of detecting biomarker molecules of extant and extinct Earth-like life in liquid extracts of martian samples with an antibody microarray assay. The aim of the work reported here was to investigate whether the presence of perchlorate salts, at levels similar to those at the NASA Phoenix landing site, would compromise the LMC extraction and detection method. To test this, we implemented an LMC-representative sample extraction process with an LMC-representative antibody assay and used these to extract and analyze a model sample that consisted of a Mars analog sample matrix (JSC Mars-1) spiked with a representative organic molecular target (pyrene, an example of abiotic meteoritic infall targets) in the presence of perchlorate salts. We found no significant change in immunoassay function when using pyrene standards with added perchlorate salts. When model samples spiked with perchlorate salts were subjected to an LMC-representative liquid extraction, immunoassays functioned in a liquid extract and detected extracted pyrene. For the same model sample matrix without perchlorate salts, we observed anomalous assay signals that coincided with yellow coloration of the extracts. This unexpected observation is being studied further. This initial study indicates that the presence of perchlorate salts, at levels similar to those detected at the NASA Phoenix landing site, is unlikely to prevent the LMC from extracting and detecting organic molecules from

  18. Interstellar PAH analogs in the laboratory: A step toward the identification and the quantification of organic molecules in space

    Science.gov (United States)

    Biennier, L.; Salama, F.; Gupta, M.; O'Keefe, A.

    In spite of recent progress in our understanding of the organic component of interstellar dust, little has been revealed about the identification and the quantification of large organic molecules in space (e.g., column densities of specific molecular species, physical and chemical processes of formation and destruction, etc...). Experimental studies of "true" cosmic organic analogs are essential to address theses issues. In our laboratory, we have developed a dedicated chamber to generate species under space-like conditions (i.e., free, cold, neutral and ionized species). The chamber is combined with a powerful state-of-the-art instrument to characterize the spectral fingerprints of these molecular species. Polycylic Aromatic Hydrocarbon (PAH) molecules are the precursors/building blocks of complex organic molecules and have been the first targets studied using this innovative approach. Our measurements provide data that can now be directly compared to astronomical spectra of the interstellar (IS) extinction curve and of the diffuse interstellar bands (DIBs), both tracers of cosmic organics. The harsh physical conditions of the diffuse IS medium - characterized by a low temperature, an absence of collisions and strong VUV radiation fields - are simulated in the laboratory by associating a free jet expansion with an ionizing discharge that altogether generate a cold plasma expansion in the chamber. The spectra of these organics are measured using two complementary high sensitivity techniques: Cavity Ring Down Spectroscopy (CRDS) and Multiplex Integrated Cavity Output Spectroscopy (MICOS). These two techniques have been applied to the measurement of the electronic spectrum of a set of representative PAHs such as the cold Naphthalene (C10H_8}) cation, neutral Methylnaphthalene (C11H10}), neutral and ionized Acenaphtene (C12H10), neutral Phenanthrene (C14H10), and neutral and ionized Pyrene (C16H10). These experiments provide unique information on the spectra of free

  19. Digital Microfluidics Assisted Sealing of Individual Magnetic Particles in Femtoliter-Sized Reaction Wells for Single-Molecule Detection.

    Science.gov (United States)

    Decrop, Deborah; Ruiz, Elena Pérez; Kumar, Phalguni Tewari; Tripodi, Lisa; Kokalj, Tadej; Lammertyn, Jeroen

    2017-01-01

    Digital microfluidics has emerged in the last years as a promising liquid handling technology for a variety of applications. Here, we describe in detail how to build up an electrowetting-on-dielectric-based digital microfluidic chip with unique advantages for performing single-molecule detection. We illustrate how superparamagnetic particles can be printed with very high loading efficiency (over 98 %) and single-particle resolution in the microwell array patterned in the Teflon-AF ® surface of the grounding plate of the chip. Finally, the potential of the device for its application to single-molecule detection is demonstrated by the ultrasensitive detection of the biotinylated enzyme β-Galactosidase captured on streptavidin-coated particles in the described platform.

  20. Optical system for object detection and delineation in space

    Science.gov (United States)

    Handelman, Amir; Shwartz, Shoam; Donitza, Liad; Chaplanov, Loran

    2018-01-01

    Object recognition and delineation is an important task in many environments, such as in crime scenes and operating rooms. Marking evidence or surgical tools and attracting the attention of the surrounding staff to the marked objects can affect people's lives. We present an optical system comprising a camera, computer, and small laser projector that can detect and delineate objects in the environment. To prove the optical system's concept, we show that it can operate in a hypothetical crime scene in which a pistol is present and automatically recognize and segment it by various computer-vision algorithms. Based on such segmentation, the laser projector illuminates the actual boundaries of the pistol and thus allows the persons in the scene to comfortably locate and measure the pistol without holding any intermediator device, such as an augmented reality handheld device, glasses, or screens. Using additional optical devices, such as diffraction grating and a cylinder lens, the pistol size can be estimated. The exact location of the pistol in space remains static, even after its removal. Our optical system can be fixed or dynamically moved, making it suitable for various applications that require marking of objects in space.

  1. Exotic Molecules in Space: A Coordinated Astronomical Laboratory and Theoretical Study

    Science.gov (United States)

    Stringfellow, Guy (Technical Monitor); Thaddeus, Patrick

    2004-01-01

    The final report covers the two year of a grant which represents a direct continuation of NASA NAG5-4050, with the same title as before. It is dedicated as before to the discovery and characterization of new astrophysical molecules. The four years (two of the original grant plus two years extension) have been extremely productive, yielding many new discoveries of astronomical interest at both radio and optical wavelengths, and the publication or submission of the 49 papers listed below. These articles have appeared or will soon appear in the leading refereed journals of astrophysics, chemical physics, physics, or molecular spectroscopy. One is a major invited review (#27) for Moleculur Physics. One of our other invited reviews published in Spectrochimica Acta in 2001 was recently awarded the Sir Harold Thompson Memorial Award, annually given to the best paper in that journal. Michael McCarthy has recently been awarded the Broida Prize.

  2. Gravitational Wave Detection by Interferometry (Ground and Space

    Directory of Open Access Journals (Sweden)

    Matthew Pitkin

    2011-07-01

    Full Text Available Significant progress has been made in recent years on the development of gravitational-wave detectors. Sources such as coalescing compact binary systems, neutron stars in low-mass X-ray binaries, stellar collapses and pulsars are all possible candidates for detection. The most promising design of gravitational-wave detector uses test masses a long distance apart and freely suspended as pendulums on Earth or in drag-free spacecraft. The main theme of this review is a discussion of the mechanical and optical principles used in the various long baseline systems in operation around the world - LIGO (USA, Virgo (Italy/France, TAMA300 and LCGT (Japan, and GEO600 (Germany/U.K. - and in LISA, a proposed space-borne interferometer. A review of recent science runs from the current generation of ground-based detectors will be discussed, in addition to highlighting the astrophysical results gained thus far. Looking to the future, the major upgrades to LIGO (Advanced LIGO, Virgo (Advanced Virgo, LCGT and GEO600 (GEO-HF will be completed over the coming years, which will create a network of detectors with the significantly improved sensitivity required to detect gravitational waves. Beyond this, the concept and design of possible future "third generation" gravitational-wave detectors, such as the Einstein Telescope (ET, will be discussed.

  3. Functionalisation of the hinge region in receptor molecules for explosive detection

    DEFF Research Database (Denmark)

    Krebs, Frederik C

    2003-01-01

    The functionalisation of the hinge region in a molecular tweezer molecule showing a strong binding to explosives is presented. Two versatile functional groups are introduced, a carboxylic acid and a bromine atom. (C) 2003 Elsevier Ltd. All rights reserved.......The functionalisation of the hinge region in a molecular tweezer molecule showing a strong binding to explosives is presented. Two versatile functional groups are introduced, a carboxylic acid and a bromine atom. (C) 2003 Elsevier Ltd. All rights reserved....

  4. Fast and efficient molecule detection in localization-based super-resolution microscopy by parallel adaptive histogram equalization.

    Science.gov (United States)

    Li, Yiming; Ishitsuka, Yuji; Hedde, Per Niklas; Nienhaus, G Ulrich

    2013-06-25

    In localization-based super-resolution microscopy, individual fluorescent markers are stochastically photoactivated and subsequently localized within a series of camera frames, yielding a final image with a resolution far beyond the diffraction limit. Yet, before localization can be performed, the subregions within the frames where the individual molecules are present have to be identified-oftentimes in the presence of high background. In this work, we address the importance of reliable molecule identification for the quality of the final reconstructed super-resolution image. We present a fast and robust algorithm (a-livePALM) that vastly improves the molecule detection efficiency while minimizing false assignments that can lead to image artifacts.

  5. New Molecular Detections in TMC-1 with the Green Bank Telescope: Carbon-Chain and Aromatic Molecules

    Science.gov (United States)

    Burkhardt, Andrew Michael

    2018-01-01

    Polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic nitrogen heterocycles PA(N)Hs are believed to be widespread throughout the Universe, and are likely responsible for the unidentified infrared bands. However, the individual detection of aromatic molecules has been limited to a single weak absorption feature of an infrared bending mode of benzene (c-C6H6). The cold core TMC-1 has long been a source of new molecular detections, particularly for unsaturated carbon-rich molecules that are appealing potential precursors of PA(N)Hs. Through deep observations with the Green Bank Telescope of TMC-1, we report the first rotational detection of an aromatic molecule, benzonitrile (c-C6H5CN), along with 8 new isotopologues of HC5N and HC7N and an entirely new molecular family (HC5O, HC7O). These new detections provide crucial insights to the formation of PAHs and the underlying carbon-chain chemistry of dark clouds.

  6. Single Molecule 3D Orientation in Time and Space: A 6D Dynamic Study on Fluorescently Labeled Lipid Membranes

    DEFF Research Database (Denmark)

    Börner, Richard; Ehrlich, Nicky; Hohlbein, Johannes

    2016-01-01

    . As the method is based on the detection of single photons, it additionally allows for performing fluorescence correlation spectroscopy (FCS) as well as dynamical anisotropy measurements thereby providing access to fast orientational dynamics down to the nanosecond time scale. The 3D orientation is particularly...... interesting in non-isotropic environments such as lipid membranes, which are of great importance in biology. We used giant unilamellar vesicles (GUVs) labeled with fluorescent dyes down to a single molecule concentration as a model system for both, assessing the robustness of the orientation determination...... simulations of the rotational dynamics of dipoles incorporated into lipid membranes. Our study offers a comprehensive view on the dye orientation behavior in a lipid membrane with high spatiotemporal resolution representing a six-dimensional fluorescence detection approach....

  7. Cathepsin G-mediated proteolytic degradation of MHC class I molecules to facilitate immune detection of human glioblastoma cells.

    Science.gov (United States)

    Palesch, David; Wagner, Johanna; Meid, Annika; Molenda, Nicole; Sienczyk, Marcin; Burkhardt, Jutta; Münch, Jan; Prokop, Lea; Stevanovic, Stefan; Westhoff, Mike-Andrew; Halatsch, Marc-Eric; Wirtz, Christian Rainer; Zimecki, Michal; Burster, Timo

    2016-03-01

    To mount an adaptive immune response, MHC I molecules present antigenic peptides to CTLs. Transcriptional reduction of MHC I molecules is a strategy of immune evasion, which impairs the detection of infected or tumorous cells by CTLs. Natural killer (NK) cells, on the other hand, eliminate target cells specifically in the absence of MHC I. Consequently, infected or tumorous cells partly retain their MHC I at the cell surface to avoid NK recognition. However, it remains unclear which protease degrades MHC I molecules and how these cells maintain a limited set of MHC I at the cell surface. Here, we demonstrate that cathepsin G (CatG), a serine protease, found in the endocytic compartment of APCs and, to a lesser extent, CatD and CatS proteolytically degrade MHC I molecules. Inhibition of CatG boosted MHC I expression at the cell surface of primary human immune cells. In contrast, human glioblastoma cells do not harbor active CatG and might have lost the ability to proteolytically degrade MHC I during tumorigenesis to avoid NK-mediated killing. Overexpression of CatG in glioblastoma cells resulted in a rapid and efficient MHC I degradation. In conclusion, CatG is an essential protease for regulating MHC I molecules and thus modulation of CatG activity might present a new avenue for therapeutic intervention.

  8. Fabrication of Chitosan-gold Nanocomposites Combined with Optical Fiber as SERS Substrates to Detect Dopamine Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jaewook; Kang, Ikjoong [Gachon Univ., Seongnam (Korea, Republic of)

    2014-01-15

    This research was aimed to fabricate an optical fiber-based SERS substrate which can detect dopamine neurotransmitters. Chitosan nanoparticles (NPs) were firstly anchored on the surface of optical fiber, and then gold layer was subseque N{sub T}ly deposited on the anchored chitosan NPs via electroless plating method. Finally, chitosan-gold nanocomposites combined with optical fiber reacted with dopamine molecules of 100-1500 mg/ day which is a standard daily dose for Parkinson's disease patientss. The amplified Raman signal at 1348 cm{sup -1} obtained from optical fiber-based SERS substrate was plotted versus dopamine concentrations (1-10 mM), demonstrating an approximate linearity of Y = 303.03X + 2385.8 (R{sup 2} = 0.97) with narrow margin errors. The optical fiber-based Raman system can be potentially applicable to in-vitro (or in-vivo) detection of probe molecules.

  9. Detection of single molecules with a scanning near-field optical microscope: Absorption and luminescence

    International Nuclear Information System (INIS)

    Plakhotnik, T.V.

    1995-01-01

    An analysis is given of the absorption and emission of single molecules located in the waist of a Gaussian beam with diameter smaller than the wavelength of light or near a conducting flat screen with a round aperture. The intensity of light in the far field was determined from the self-consistent solution of Maxwell's equations with appropriate boundary conditions. It is shown that the intensity, shape, and position of absorption and luminescence spectral lines measured in a broad beam significantly change if a molecule is located near the waist or the aperture. If their diameter is far smaller than the wavelength of light, then the presence of a molecule that is resonant with the exciting field results in an increase in the intensity of light in the far field, i.e., in negative absorption. 19 refs., 3 figs

  10. MOCCA: A 4k-Pixel Molecule Camera for the Position- and Energy-Resolving Detection of Neutral Molecule Fragments at CSR

    Science.gov (United States)

    Gamer, L.; Schulz, D.; Enss, C.; Fleischmann, A.; Gastaldo, L.; Kempf, S.; Krantz, C.; Novotný, O.; Schwalm, D.; Wolf, A.

    2016-08-01

    We present the design of MOCCA, a large-area particle detector that is developed for the position- and energy-resolving detection of neutral molecule fragments produced in electron-ion interactions at the Cryogenic Storage Ring at the Max Planck Institute for Nuclear Physics in Heidelberg. The detector is based on metallic magnetic calorimeters and consists of 4096 particle absorbers covering a total detection area of 44.8 mathrm {mm} × 44.8 mathrm {mm}. Groups of four absorbers are thermally coupled to a common paramagnetic temperature sensor where the strength of the thermal link is different for each absorber. This allows attributing a detector event within this group to the corresponding absorber by discriminating the signal rise times. A novel readout scheme further allows reading out all 1024 temperature sensors that are arranged in a 32 × 32 square array using only 16+16 current-sensing superconducting quantum interference devices. Numerical calculations taking into account a simplified detector model predict an energy resolution of Δ E_mathrm {FWHM} le 80 mathrm {eV} for all pixels of this detector.

  11. Comparison of enclosed space detection system with conventional methods

    International Nuclear Information System (INIS)

    Kercel, S.W.; Baylor, V.M.; Labaj, L.E.

    1997-01-01

    Enclosed Space Detection System (ESDS) is a fast, inexpensive, and reliable device for detecting human occupants hidden in vehicles. Operation requires less than two minutes. ESDS is used to foil attempts at smuggling illegal aliens, terrorists, and escaping prisoners. It is being tested at nuclear weapons facilities and has been operated at several prisons and international border crossings. ESDS is the first practical electronic alternative to physical searches of vehicles for hidden passengers. At critical checkpoints, a thorough physical search of a single fully loaded truck requires a team of from two to six people, and may take as long as eight hours. Despite this level of security, experience has shown that the search can occasionally be foiled. Due to the enormous time and expense of thorough physical searches of vehicles, they are seldom conducted at any but the most critical of locations, simply leaving many sites vulnerable to crime and terrorism. Prior to the development of the ESDS, the only other effective alternative to physical search was the use of specially-trained canines, which can be vastly superior to the physical search in both time and accuracy. However, as discussed in this paper, canine inspection is not really a competitive substitute for ESDS because canine reliability (80% at most) is not as high as that of the ESDS (99%+), while the costs, training requirements, and operator skill needed are significantly higher with canines than with the ESDS. In addition, the ESDS has straightforward self-diagnostic tests to ensure the system is operating correctly; such tests are not currently available with either canine or human inspectors. ESDS offers an attractive supplement or alternative to meet current security requirements for vehicle searches at portals at government, nuclear, industrial, and other facilities where concealed persons may pose a threat either by entering or leaving

  12. Comparison of enclosed space detection system with conventional methods

    Energy Technology Data Exchange (ETDEWEB)

    Kercel, S.W.; Baylor, V.M.; Labaj, L.E.

    1997-09-01

    Enclosed Space Detection System (ESDS) is a fast, inexpensive, and reliable device for detecting human occupants hidden in vehicles. Operation requires less than two minutes. ESDS is used to foil attempts at smuggling illegal aliens, terrorists, and escaping prisoners. It is being tested at nuclear weapons facilities and has been operated at several prisons and international border crossings. ESDS is the first practical electronic alternative to physical searches of vehicles for hidden passengers. At critical checkpoints, a thorough physical search of a single fully loaded truck requires a team of from two to six people, and may take as long as eight hours. Despite this level of security, experience has shown that the search can occasionally be foiled. Due to the enormous time and expense of thorough physical searches of vehicles, they are seldom conducted at any but the most critical of locations, simply leaving many sites vulnerable to crime and terrorism. Prior to the development of the ESDS, the only other effective alternative to physical search was the use of specially-trained canines, which can be vastly superior to the physical search in both time and accuracy. However, as discussed in this paper, canine inspection is not really a competitive substitute for ESDS because canine reliability (80% at most) is not as high as that of the ESDS (99%+), while the costs, training requirements, and operator skill needed are significantly higher with canines than with the ESDS. In addition, the ESDS has straightforward self-diagnostic tests to ensure the system is operating correctly; such tests are not currently available with either canine or human inspectors. ESDS offers an attractive supplement or alternative to meet current security requirements for vehicle searches at portals at government, nuclear, industrial, and other facilities where concealed persons may pose a threat either by entering or leaving.

  13. Theoretical Basis for Stochastic Optimization Starting from a Single Point in the Search Space Formed by Real DNA Molecules

    Science.gov (United States)

    Someya, Hiroshi; Yamamura, Masayuki; Sakamoto, Kensaku

    This paper discusses DNA-based stochastic optimizations under the constraint that the search starts from a given point in a search space. Generally speaking, a stochastic optimization method explores a search space and finds out the optimum or a sub-optimum after many cycles of trials and errors. This search process could be implemented efficiently by ``molecular computing'', which processes DNA molecules by the techniques of molecular biology to generate and evaluate a vast number of solution candidates at a time. We assume the exploration starting from a single point, and propose a method to embody DNA-based optimization under this constraint, because this method has a promising application in the research field of protein engineering. In this application, a string of nucleotide bases (a base sequence) encodes a protein possessing a specific activity, which could be given as a value of an objective function. Thus, a problem of obtaining a protein with the optimum or a sub-optimum about the desired activity corresponds to a combinatorial problem of obtaining a base sequence giving the optimum or a sub-optimum in the sequence space. Biologists usually modify a base sequence corresponding to a naturally occurring protein into another sequence giving a desired activity. In other words, they explore the space in the proximity of a natural protein as a start point. We first examined if the optimization methods that involve a single start point, such as simulated annealing, Gibbs sampler, and MH algorithms, can be implemented by DNA-based operations. Then, we proposed an application of genetic algorithm, and examined the performance of this application on a model fitness landscape by computer experiments. These experiments gave helpful guidelines in the embodiments of DNA-based stochastic optimization, including a better design of crossover operator.

  14. Space Shuttle Main Propulsion System Anomaly Detection: A Case Study

    Data.gov (United States)

    National Aeronautics and Space Administration — The space shuttle main engine (SSME) is part of the Main Propnlsion System (MPS) which is an extremely complex system containing several sub-systems and components,...

  15. Microfluidic Label-Free Sensing for Rapid Multiplexed Pathogen Detection in Space Missions

    Data.gov (United States)

    National Aeronautics and Space Administration — For the success of most space programs involving environmental control and waste water management, the rapid detection and identification of pathogens under resource...

  16. Ultra-Low Noise Quad Photoreceiver for Space Based Laser Interferometric Gravity Wave Detection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gravity wave detection using space-based long-baseline laser interferometric sensors imposes stringent noise requirements on the system components, including the...

  17. Highly sensitivity adhesion molecules detection in hereditary haemochromatosis patients reveals altered expression.

    LENUS (Irish Health Repository)

    Norris, S

    2012-02-01

    Several abnormalities in the immune status of patients with hereditary haemochromatosis (HH) have been reported, suggesting an imbalance in their immune function. This may include persistent production of, or exposure to, altered immune signalling contributing to the pathogenesis of this disorder. Adhesion molecules L-, E- and P-Selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) are some of the major regulators of the immune processes and altered levels of these proteins have been found in pathological states including cardiovascular diseases, arthritis and liver cancer. The aim of this study was to assess L-, E- and P-Selectin, ICAM-1 and VCAM-1 expression in patients with HH and correlate these results with HFE mutation status and iron indexes. A total of 139 subjects were diagnosed with HH (C282Y homozygotes = 87, C282Y\\/H63D = 26 heterozygotes, H63D homozygotes = 26), 27 healthy control subjects with no HFE mutation (N\\/N), 18 normal subjects heterozygous for the H63D mutation served as age-sex-matched controls. We observed a significant decrease in L-selectin (P = 0.0002) and increased E-selectin and ICAM-1 (P = 0.0006 and P = 0.0059) expression in HH patients compared with healthy controls. This study observes for the first time that an altered adhesion molecules profile occurs in patients with HH that is associated with specific HFE genetic component for iron overload, suggesting that differential expression of adhesion molecules may play a role in the pathogenesis of HH.

  18. Tentative detection of the nitrosylium ion in space

    Energy Technology Data Exchange (ETDEWEB)

    Cernicharo, J.; Tercero, B. [Departamento de Astrofísica, Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, E-28850 Madrid (Spain); Bailleux, S. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR 8523 CNRS, Université Lille 1, F-59655 Villeneuve d' Ascq Cedex (France); Alekseev, E. [Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Krasnoznamennaya ul. 4, Kharkov 61002 (Ukraine); Fuente, A.; Bachiller, R. [Observatorio Astronómico Nacional, Apdo. 112, E-28803 Alcalá de Henares (Spain); Roueff, E. [LERMA, Observatoire de Paris, CNRS UMR 8112. Place J. Janssen, F-92190 Meudon (France); Gerin, M. [LERMA, Observatoire de Paris, CNRS UMR8112 and Ecole Normale Superieure, 61 Avenue de l' Observatoire, F-75014 Paris (France); Treviño-Morales, S. P. [Instituto de Radio Astronomía Milimétrica (IRAM), Avenida Divina Pastora 7, Local 20, E-18012 Granada (Spain); Marcelino, N. [NRAO, 520 Edgemont Road, Charlottesville, VA 22902 (United States); Lefloch, B. [UJF-Grenoble/CNRS-INSU, Institut de Planétologie et d' Astrophysique de Grenoble (IPAG) UMR 5274, F-38041 Grenoble (France)

    2014-11-01

    We report the tentative detection in space of the nitrosylium ion, NO{sup +}. The observations were performed toward the cold dense core Barnard 1-b. The identification of the NO{sup +} J = 2-1 line is supported by new laboratory measurements of NO{sup +} rotational lines up to the J = 8-7 transition (953207.189 MHz), which leads to an improved set of molecular constants: B {sub 0} = 59597.1379(62) MHz, D {sub 0} = 169.428(65) kHz, and eQq {sub 0}(N) = –6.72(15) MHz. The profile of the feature assigned to NO{sup +} exhibits two velocity components at 6.5 and 7.5 km s{sup –1}, with column densities of 1.5 × 10{sup 12} and 6.5 × 10{sup 11} cm{sup –2}, respectively. New observations of NO and HNO, also reported here, allow us to estimate the following abundance ratios: X(NO)/X(NO{sup +}) ≅ 511, and X(HNO)/X(NO{sup +}) ≅ 1. This latter value provides important constraints on the formation and destruction processes of HNO. The chemistry of NO{sup +} and other related nitrogen-bearing species is investigated by the means of a time-dependent gas phase model which includes an updated chemical network according to recent experimental studies. The predicted abundance for NO{sup +} and NO is found to be consistent with the observations. However, that of HNO relative to NO is too high. No satisfactory chemical paths have been found to explain the observed low abundance of HNO. HSCN and HNCS are also reported here with an abundance ratio of ≅ 1. Finally, we have searched for NNO, NO{sub 2}, HNNO{sup +}, and NNOH{sup +}, but only upper limits have been obtained for their column density, except for the latter for which we report a tentative 3σ detection.

  19. A novel aptasensor based on single-molecule force spectroscopy for highly sensitive detection of mercury ions.

    Science.gov (United States)

    Li, Qing; Michaelis, Monika; Wei, Gang; Colombi Ciacchi, Lucio

    2015-08-07

    We have developed a novel aptasensor based on single-molecule force spectroscopy (SMFS) capable of detecting mercury ions (Hg(2+)) with sub-nM sensitivity. The single-strand (ss) DNA aptamer used in this work is rich in thymine (T) and readily forms T-Hg(2+)-T complexes in the presence of Hg(2+). The aptamer was conjugated to an atomic force microscope (AFM) probe, and the adhesion force between the probe and a flat graphite surface was measured by single-molecule force spectroscopy (SMFS). The presence of Hg(2+) ions above a concentration threshold corresponding to the affinity constant of the ions for the aptamer (about 5 × 10(9) M(-1)) could be easily detected by a change of the measured adhesion force. With our chosen aptamer, we could reach an Hg(2+) detection limit of 100 pM, which is well below the maximum allowable level of Hg(2+) in drinking water. In addition, this aptasensor presents a very high selectivity for Hg(2+) over other metal cations, such as K(+), Ca(2+), Zn(2+), Fe(2+), and Cd(2+). Furthermore, the effects of the ionic strength and loading rate on the Hg(2+) detection were evaluated. Its simplicity, reproducibility, high selectivity and sensitivity make our SMFS-based aptasensor advantageous with respect to other current Hg(2+) sensing methods. It is expected that our strategy can be exploited for monitoring the pollution of water environments and the safety of potentially contaminated food.

  20. Toward single-molecule detection with sensors based on propagating surface plasmons

    Czech Academy of Sciences Publication Activity Database

    Kvasnička, Pavel; Chadt, Karel; Vala, Milan; Bocková, Markéta; Homola, Jiří

    2012-01-01

    Roč. 37, č. 2 (2012), s. 163-165 ISSN 0146-9592 R&D Projects: GA AV ČR KAN200670701; GA MŠk OC09058; GA MŠk(CZ) LH11102 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical biosenzor * single molecule * surface plasmon microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.385, year: 2012

  1. Detecting level crossings without solving the Hamiltonian. II. Applications to atoms and molecules

    International Nuclear Information System (INIS)

    Bhattacharya, M.; Raman, C.

    2007-01-01

    A number of interesting phenomena occur at points where the energy levels of an atom or a molecule (anti) cross as a function of some parameter such as an external field. In a previous paper [M. Bhattacharya and C. Raman, Phys. Rev. Lett. 97, 140405 (2006)] we have outlined powerful mathematical techniques useful in identifying the parameter values at which such (avoided) crossings occur. In the accompanying article [M. Bhattacharya and C. Raman, Phys. Rev A 75, 033405 (2007)] we have developed the mathematical basis of these algebraic techniques in some detail. In this article we apply these level-crossing methods to the spectra of atoms and molecules in a magnetic field. In the case of atoms the final result is the derivation of a class of invariants of the Breit-Rabi Hamiltonian of magnetic resonance. These invariants completely describe the parametric symmetries of the Hamiltonian. In the case of molecules we present an indicator which can tell when the Born-Oppenheimer approximation breaks down without using any information about the molecular potentials other than the fact that they are real. We frame our discussion in the context of Feshbach resonances in the atom-pair 23 Na- 85 Rb which are of current interest

  2. Standoff Detection of Trace Molecules by Remote High Gain Backward Lasing in Air

    Science.gov (United States)

    2016-09-17

    lasing in air from numerous atomic species. Backward lasing may provide a high sensitivity method for the detection of greenhouse gases , gas leakage...backward lasing from natural constituents in air with the objective of developing revolutionary methods for standoff detection of trace gases . Backward...and Environment Congress, Canberra, Australia (2014), invited. 12. R. B. Miles and A. Dogariu, “"Flow Imaging and Standoff Detection by Dissociation

  3. Fiber optic microsensor technology for detection of hydrogen in space applications

    Science.gov (United States)

    Kazemi, Alex A.

    2008-04-01

    Optical hydrogen sensors are intrinsically safe since they produce no arc or spark in an explosive environment caused by the leakage of hydrogen. Safety remains a top priority since leakage of hydrogen in air during production, storage, transfer and distribution creates an explosive atmosphere for concentrations between 4% (v/v) - the lower explosive limit (LEL) and 74.5% (v/v) - the upper explosive limit (UEL) at room temperature and pressure. Being a very small molecule, hydrogen is prone to leakage through seals and micro-cracks. Hydrogen detection in space application is very challenging; public acceptance of hydrogen fuel would require the integration of a reliable hydrogen safety sensor. For detecting leakage of cryogenic fluids in spaceport facilities, Launch vehicle industry and aerospace agencies are currently relying heavily on the bulky mass spectrometers, which fill one or more equipment racks, and weigh several hundred kilograms. This paper describes the successful development and test of a multi-point fiber optic hydrogen sensor system during the static firing of an Evolved Expandable Launch Vehicle at NASA's Stennis Space Center. The system consisted of microsensors (optrodes) using hydrogen gas sensitive indicator incorporated onto an optically transparent porous substrate. The modular optoelectronics and multiplexing network system was designed and assembled utilizing a multi-channel optoelectronic sensor readout unit that monitored the hydrogen and temperature response of the individual optrodes in real-time and communicated this information via a serial communication port to a remote laptop computer. The paper would discuss the sensor design and performance data under field deployment conditions.

  4. Capture, unfolding, and detection of individual tRNA molecules using a nanopore device

    Directory of Open Access Journals (Sweden)

    Andrew M Smith

    2015-06-01

    Full Text Available Transfer RNAs (tRNA are the most common RNA molecules in cells and have critical roles as both translators of the genetic code and regulators of protein synthesis. As such, numerous methods have focused on studying tRNA abundance and regulation, with the most widely used methods being RNA-seq and microarrays. Though revolutionary to transcriptomics, these assays are limited by an inability to encode tRNA modifications in the requisite cDNA. These modifications are abundant in tRNA and critical to their function. Here we describe proof-of-concept experiments where individual tRNA molecules are examined as linear strands using a biological nanopore. This method utilizes an enzymatically ligated synthetic DNA adapter to concentrate tRNA at the lipid bilayer of the nanopore device and efficiently denature individual tRNA molecules as they are pulled through the α-hemolysin (α-HL nanopore. Additionally, the DNA adapter provides a loading site for ϕ29 DNA polymerase (ϕ29 DNAP, which acts as a brake on the translocating tRNA. This increases the dwell time of adapted tRNA in the nanopore, allowing us to identify the region of the nanopore signal that is produced by the translocating tRNA itself. Using adapter-modified E. coli tRNAfMet and tRNALys, we show that the nanopore signal during controlled translocation is dependent on the identity of the tRNA. This confirms that adapter-modified tRNA can translocate end-to-end through nanopores and provides the foundation for future work in direct sequencing of individual transfer RNA with a nanopore-based device.

  5. Capture, Unfolding, and Detection of Individual tRNA Molecules Using a Nanopore Device

    Science.gov (United States)

    Smith, Andrew M.; Abu-Shumays, Robin; Akeson, Mark; Bernick, David L.

    2015-01-01

    Transfer RNAs (tRNA) are the most common RNA molecules in cells and have critical roles as both translators of the genetic code and regulators of protein synthesis. As such, numerous methods have focused on studying tRNA abundance and regulation, with the most widely used methods being RNA-seq and microarrays. Though revolutionary to transcriptomics, these assays are limited by an inability to encode tRNA modifications in the requisite cDNA. These modifications are abundant in tRNA and critical to their function. Here, we describe proof-of-concept experiments where individual tRNA molecules are examined as linear strands using a biological nanopore. This method utilizes an enzymatically ligated synthetic DNA adapter to concentrate tRNA at the lipid bilayer of the nanopore device and efficiently denature individual tRNA molecules, as they are pulled through the α-hemolysin (α-HL) nanopore. Additionally, the DNA adapter provides a loading site for ϕ29 DNA polymerase (ϕ29 DNAP), which acts as a brake on the translocating tRNA. This increases the dwell time of adapted tRNA in the nanopore, allowing us to identify the region of the nanopore signal that is produced by the translocating tRNA itself. Using adapter-modified Escherichia coli tRNAfMet and tRNALys, we show that the nanopore signal during controlled translocation is dependent on the identity of the tRNA. This confirms that adapter-modified tRNA can translocate end-to-end through nanopores and provide the foundation for future work in direct sequencing of individual transfer RNA with a nanopore-based device. PMID:26157798

  6. High-harmonic homodyne detection of the ultrafast dissociation of Br2 molecules.

    Science.gov (United States)

    Wörner, H J; Bertrand, J B; Corkum, P B; Villeneuve, D M

    2010-09-03

    We report the time-resolved observation of the photodissociation of Br2 using high-harmonic generation (HHG) as a probe. The simultaneous measurement of the high-harmonic and ion yields shows that high harmonics generated by the electronically excited state interfere with harmonics generated by the ground state. The resulting homodyne effect provides a high sensitivity to the excited state dynamics. We present a simple theoretical model that accounts for the main observations. Our experiment paves the way towards the dynamic imaging of molecules using HHG.

  7. Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, C. Stefan; Ram, N. Bhargava; Janssen, Maurice H. M., E-mail: m.h.m.janssen@vu.nl [LaserLaB Amsterdam, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Powis, Ivan [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2013-12-21

    Here, we provide a detailed account of novel experiments employing electron-ion coincidence imaging to discriminate chiral molecules. The full three-dimensional angular scattering distribution of electrons is measured after photoexcitation with either left or right circular polarized light. The experiment is performed using a simplified photoelectron-photoion coincidence imaging setup employing only a single particle imaging detector. Results are reported applying this technique to enantiomers of the chiral molecule camphor after three-photon ionization by circularly polarized femtosecond laser pulses at 400 nm and 380 nm. The electron-ion coincidence imaging provides the photoelectron spectrum of mass-selected ions that are observed in the time-of-flight mass spectra. The coincident photoelectron spectra of the parent camphor ion and the various fragment ions are the same, so it can be concluded that fragmentation of camphor happens after ionization. We discuss the forward-backward asymmetry in the photoelectron angular distribution which is expressed in Legendre polynomials with moments up to order six. Furthermore, we present a method, similar to one-photon electron circular dichroism, to quantify the strength of the chiral electron asymmetry in a single parameter. The circular dichroism in the photoelectron angular distribution of camphor is measured to be 8% at 400 nm. The electron circular dichroism using femtosecond multiphoton excitation is of opposite sign and about 60% larger than the electron dichroism observed before in near-threshold one-photon ionization with synchrotron excitation. We interpret our multiphoton ionization as being resonant at the two-photon level with the 3s and 3p Rydberg states of camphor. Theoretical calculations are presented that model the photoelectron angular distribution from a prealigned camphor molecule using density functional theory and continuum multiple scattering X alpha photoelectron scattering calculations

  8. Detection of circulating methylated opioid binding protein/cell adhesion molecule-like gene as a biomarker for ovarian carcinoma.

    Science.gov (United States)

    Zhou, Feng; Ma, Min; Tao, Guohua; Chen, Xiang; Xie, Wei; Wang, Ying; Cao, Xingjian

    2014-01-01

    Hypermethylation of the opioid binding protein/cell adhesion molecule-like (OPCML) gene is frequently observed in ovarian carcinoma. We evaluated the detection of circulating hypermethylated OPCML for detecting ovarian carcinoma and assessing its prognosis. We studied 85 tissue samples including 45 ovarian cancer tissues and 40 normal ovarian tissues and blood samples from 45 ovarian cancer patients and 20 healthy individuals. Bisulfite sequencing and methylation-sensitive restriction enzyme-PCR (MSRE-PCR) were used to detect the frequency of OPCML hypermethylation. We detected that the frequency of OPCML hypermethylation for tissue and serum samples in ovarian carcinoma were 86.7% (39/45) and 80.0% (36/45), respectively, but none was detected in ovarian tissue and serum of healthy individuals. The frequency of OPCML hypermethylation in endometrioid carcinoma, serous cystadenocarcinoma, mucinous cystadenocarcinoma, clear cell carcinoma, and undifferentiated carcinoma were 80.0%, 85.5%, 50.0%, 80.0%, and 100%, respectively (p > 0.05). The frequencies of OPCML hypermethylation in patients were also different in terms of tumor differentiation degree. We detected hypermethylated OPCML in the sera of 50% of well differentiated, 62.5% of moderately differentiated, 93.1% of poorly differentiated tumors (p ovarian carcinoma diagnosis.

  9. Using Metal Complex Ion-Molecule Reactions in a Miniature Rectilinear Ion Trap Mass Spectrometer to Detect Chemical Warfare Agents

    Science.gov (United States)

    Graichen, Adam M.; Vachet, Richard W.

    2013-06-01

    The gas-phase reactions of a series of coordinatively unsaturated [Ni(L)n]y+ complexes, where L is a nitrogen-containing ligand, with chemical warfare agent (CWA) simulants in a miniature rectilinear ion trap mass spectrometer were investigated as part of a new approach to detect CWAs. Results show that upon entering the vacuum system via a poly(dimethylsiloxane) (PDMS) membrane introduction, low concentrations of several CWA simulants, including dipropyl sulfide (simulant for mustard gas), acetonitrile (simulant for the nerve agent tabun), and diethyl phosphite (simulant for nerve agents sarin, soman, tabun, and VX), can react with metal complex ions generated by electrospray ionization (ESI), thereby providing a sensitive means of detecting these compounds. The [Ni(L)n]2+ complexes are found to be particularly reactive with the simulants of mustard gas and tabun, allowing their detection at low parts-per-billion (ppb) levels. These detection limits are well below reported exposure limits for these CWAs, which indicates the applicability of this new approach, and are about two orders of magnitude lower than electron ionization detection limits on the same mass spectrometer. The use of coordinatively unsaturated metal complexes as reagent ions offers the possibility of further tuning the ion-molecule chemistry so that desired compounds can be detected selectively or at even lower concentrations.

  10. Flipping the switch: Tools for detecting small molecule inhibitors of staphylococcal virulence

    Directory of Open Access Journals (Sweden)

    Cassandra L. Quave

    2014-12-01

    Full Text Available Through the expression of the accessory gene regulator (agr quorum sensing cascade, S. aureus is able to produce an extensive array of enzymes, hemolysins and immunomodulators essential to its ability to spread through the host tissues and cause disease. Many have argued for the discovery and development of quorum sensing inhibitors (QSIs to augment existing antibiotics as adjuvant therapies. Here, we discuss the state-of-the-art tools that can be used to conduct screens for the identification of such QSIs. Examples include fluorescent reporters, MS-detection of autoinducing peptide (AIP production, agar plate methods for detection of hemolysins and lipase, HPLC-detection of hemolysins from supernatants, and cell-toxicity assays for detecting damage (or relief thereof against human keratinocyte (HaCat cells. In addition to providing a description of these various approaches, we also discuss their amenability to low-, medium- and high-throughput screening efforts for the identification of novel QSIs.

  11. Selective on site separation and detection of molecules in diluted solutions with super-hydrophobic clusters of plasmonic nanoparticles

    KAUST Repository

    Gentile, Francesco T.

    2014-01-01

    Super-hydrophobic surfaces are bio-inspired interfaces with a superficial texture that, in its most common evolution, is formed by a periodic lattice of silicon micro-pillars. Similar surfaces reveal superior properties compared to conventional flat surfaces, including very low friction coefficients. In this work, we modified meso-porous silicon micro-pillars to incorporate networks of metal nano-particles into the porous matrix. In doing so, we obtained a multifunctional-hierarchical system in which (i) at a larger micrometric scale, the super-hydrophobic pillars bring the molecules dissolved in an ultralow-concentration droplet to the active sites of the device, (ii) at an intermediate meso-scale, the meso-porous silicon film adsorbs the low molecular weight content of the solution and, (iii) at a smaller nanometric scale, the aggregates of silver nano-particles would measure the target molecules with unprecedented sensitivity. In the results, we demonstrated how this scheme can be utilized to isolate and detect small molecules in a diluted solution in very low abundance ranges. The presented platform, coupled to Raman or other spectroscopy techniques, is a realistic candidate for the protein expression profiling of biological fluids. © 2014 the Partner Organisations.

  12. Cell-based protein stabilization assays for the detection of interactions between small-molecule inhibitors and BRD4.

    Science.gov (United States)

    Schulze, Jessica; Moosmayer, Dieter; Weiske, Joerg; Fernández-Montalván, Amaury; Herbst, Christopher; Jung, Marie; Haendler, Bernard; Bader, Benjamin

    2015-02-01

    Bromodomain protein 4 (BRD4), a member of the bromodomain and extra-terminal (BET) protein family, acts as a central element in transcriptional elongation and plays essential roles in cell proliferation. Inhibition of BRD4 binding to acetylated histone tails via its two bromodomains, BD1 and BD2, with small-molecule inhibitors has been shown to be a valid strategy to prevent cancer growth. We have evaluated and established two novel assays that quantify the interaction of transfected BRD4 BD1 with chemical inhibitors inside cultured cells. Both methods are based on the principle of ligand-induced protein stabilization by which the binding of a small-molecule inhibitor stabilizes intracellular BRD4 BD1 and protects it from proteolytic degradation. We demonstrate the universal character of this principle by using two orthogonal, highly sensitive detection technologies for the quantification of BRD4 BD1 levels in cellular lysates: enzyme fragment complementation and time-resolved fluorescence resonance energy transfer (TR-FRET). Upon optimization of both assays to a miniaturized high-throughput format, the methods were validated by testing a set of small-molecule BET inhibitors and comparing the results with those from a cell-free binding assay and a biophysical thermal shift assay. In addition, point mutations were introduced into BRD4 BD1, and the corresponding mutants were characterized in the TR-FRET stabilization assay. © 2014 Society for Laboratory Automation and Screening.

  13. Data-Driven Techniques for Detecting Dynamical State Changes in Noisily Measured 3D Single-Molecule Trajectories

    Directory of Open Access Journals (Sweden)

    Christopher P. Calderon

    2014-11-01

    Full Text Available Optical microscopes and nanoscale probes (AFM, optical tweezers, etc. afford researchers tools capable of quantitatively exploring how molecules interact with one another in live cells. The analysis of in vivo single-molecule experimental data faces numerous challenges due to the complex, crowded, and time changing environments associated with live cells. Fluctuations and spatially varying systematic forces experienced by molecules change over time; these changes are obscured by “measurement noise” introduced by the experimental probe monitoring the system. In this article, we demonstrate how the Hierarchical Dirichlet Process Switching Linear Dynamical System (HDP-SLDS of Fox et al. [IEEE Transactions on Signal Processing 59] can be used to detect both subtle and abrupt state changes in time series containing “thermal” and “measurement” noise. The approach accounts for temporal dependencies induced by random and “systematic overdamped” forces. The technique does not require one to subjectively select the number of “hidden states” underlying a trajectory in an a priori fashion. The number of hidden states is simultaneously inferred along with change points and parameters characterizing molecular motion in a data-driven fashion. We use large scale simulations to study and compare the new approach to state-of-the-art Hidden Markov Modeling techniques. Simulations mimicking single particle tracking (SPT experiments are the focus of this study.

  14. Detection of trans-isomers of hydrocarbon residues of lipid molecules by IR absorption

    Science.gov (United States)

    Mikhalovsky, I. S.; Samoylov, M. V.; Wileishikova, N. P.

    2009-01-01

    IR spectroscopy is used for a comparative analysis of the trans-isomerization of double bonds in hydrocarbon residuals of lactic and hydrogenated lipids. The maximum of the absorption band of the trans-isomers for all the lipid samples is found to lie at 965 cm-1. An absorption band at 970 cm-1 is discovered in the spectra of the lactic lipids near the analytic band of the trans-isomers at 965 cm-1. Based on a gaussian approximation for their absorption spectral bands, the trans-isomer content in the lactic lipid samples is 10-11%. The absorption by lipid molecules at 970 cm-1 has to be taken into account when determining the trans-isomer content of fat and oil products.

  15. Single molecule Raman spectroscopic assay to detect transgene from GM plants.

    Science.gov (United States)

    Kadam, Ulhas S; Chavhan, Rahul L; Schulz, Burkhard; Irudayaraj, Joseph

    2017-09-01

    Substantial concerns have been raised for the safety of transgenics on human health and environment. Many organizations, consumer groups, and environmental agencies advocate for stringent regulations to avoid transgene products' contamination in food cycle or in nature. Here we demonstrate a novel approach using surface enhanced Raman spectroscopy (SERS) to detect and quantify transgene from GM plants. We show a highly sensitive and accurate quantification of transgene DNA from multiple transgenic lines of Arabidopsis. The assay allows us to detect and quantify the transgenes as low as 0.10 pg without need for PCR-amplification. This technology is relatively cheap, quick, simple, and suitable for detection at low target concentration. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Simulation analysis of debris detection and removal by space-based laser

    Science.gov (United States)

    Kang, Bo-kun; Jin, Xing; Chang, Hao

    2017-10-01

    With much more attention and utilizing paying to space resource, the detection and removal of space debris, the biggest threatened to the orbiting spacecraft, has become a research hotspot in recent years. In order to protect the important space assets, such as the international space station, it has been realized of simulation and system parameters' design, which contained debris' detection and removal by space-based pulse laser. Simulation results show that the determine time of detection laser and removal laser should be considered after judging weather debris is in the "clear window". As the increasing of detection pulse and removal pulse, the orbit element of space debris has a regular change, with the decreasing of single pulse velocity increment. The system of detection and removal of space debris designed as: detection laser power 50W, removal laser power 150kW, laser wavelength 1064nm, pulse width 10ns, frequency 100Hz. The research has a great significance of detection and removal of debris by space-based laser and engineering application.

  17. Universal sensor based on the spectroscopy of glow discharge for the detection of traces of atoms or molecules in air

    Science.gov (United States)

    Atutov, S. N.; Galeyev, A. E.; Plekhanov, A. I.; Yakovlev, A. V.

    2018-03-01

    A sensitive and versatile sensor for the detection of traces of atoms or molecules in air based on the emission spectroscopy of glow discharge in air has been developed and studied. The advantages of this sensor compared to other well-known methods are that it renders the use of ultrahigh vacuum or cryogenic temperatures superfluous. The sensor is insensitive to the presence of water vapor (for example, in exhaled air) because of the absence of strong water lines in the visible spectral range. It has a high spectral selectivity limited only by Doppler broadening of the emission lines. The high selectivity of the sensor combined with a wide spectral range allows the detection of many toxic impurities, which can be present in air. Moreover, the spectral range used covers almost all biomarkers in exhaled air, making the proposed sensor extremely interesting for medical applications. To our knowledge, the proposed method is the first based on a glow discharge in air.

  18. Single-molecule detection of chaperonin dynamics through polarization rotation modulation of CdSe QD luminescence imaging

    International Nuclear Information System (INIS)

    Tani, Toshiro; Oda, Masaru; Araki, Daisuke; Miyashita, Tatsuki; Nakajima, Koudai; Arita, Mayuno; Yohda, Masafumi

    2014-01-01

    We report our recent trials examining the single-molecule three-dimensional (3D) detection of protein conformational dynamics at room temperature. Using molecular chaperones as model proteins and cadmium selenide (CdSe) semiconductor quantum dots (QDs) as nanometer-scale probes, we monitored the temporal evolution of ATP-induced conformation changes with a total internal reflection fluorescence (TIRF) microscopy imaging technique in buffer solutions. The two-dimensional (2D) degenerate nature of the emission dipoles of the QDs, due to the uniaxial wurtzite crystal structure, made it possible to capture the 3D orientation using a polarization modulation technique in real time. The temporal resolution was half the period of analyzer rotation. Although still insufficient, the obtained signals suggest possible 3D detection of specific motions, which supports the two-step conformational changes triggered by ATP attachment. - Highlights: • We report our recent trials examining the single-molecule three-dimensional (3D) detection of protein conformational dynamics at room temperature. • Using molecular chaperones as model proteins and cadmium selenide (CdSe) semiconductor quantum dots (QDs) as nanometer-scale probes, we monitored the temporal evolution of ATP-induced conformation changes with a total internal reflection fluorescence (TIRF) microscopy imaging technique in buffer solutions. • The two-dimensional (2D) degenerate nature of the emission dipoles of the QDs, due to the uniaxial wurtzite crystal structure, made it possible to capture the 3D orientation using a polarization modulation technique in real time. • The temporal resolution was half the period of analyzer rotation. • Although still insufficient, the obtained signals suggest possible 3D detection of specific motions, which supports the two-step conformational changes triggered by ATP attachment

  19. Single molecule sequencing of free DNA from maternal plasma for noninvasive trisomy 21 detection

    NARCIS (Netherlands)

    van den Oever, Jessica M. E.; Balkassmi, Sahila; Verweij, E. Joanne; van Iterson, Maarten; van Scheltema, Phebe N. Adama; Oepkes, Dick; van Lith, Jan M. M.; Hoffer, Mariëtte J. V.; den Dunnen, Johan T.; Bakker, Egbert; Boon, Elles M. J.

    2012-01-01

    Noninvasive fetal aneuploidy detection by use of free DNA from maternal plasma has recently been shown to be achievable by whole genome shotgun sequencing. The high-throughput next-generation sequencing platforms previously tested use a PCR step during sample preparation, which results in

  20. Exploring both sequence detection and restriction endonuclease cleavage kinetics by recognition site via single-molecule microfluidic trapping.

    Science.gov (United States)

    Xu, Weilin; Muller, Susan J

    2011-02-07

    We demonstrate the feasibility of a single-molecule microfluidic approach to both sequence detection and obtaining kinetic information for restriction endonucleases on dsDNA. In this method, a microfluidic stagnation point flow is designed to trap, hold, and linearize double-stranded (ds) genomic DNA to which a restriction endonuclease has been pre-bound sequence-specifically. By introducing the cofactor magnesium, we determine the binding location of the enzyme by the cleavage process of dsDNA as in optical restriction mapping, however here the DNA need not be immobilized on a surface. We note that no special labeling of the enzyme is required, which makes it simpler than our previous scheme using stagnation point flows for sequence detection. Our accuracy in determining the location of the recognition site is comparable to or better than other single molecule techniques due to the fidelity with which we can control the linearization of the DNA molecules. In addition, since the cleavage process can be followed in real time, information about the cleavage kinetics, and subtle differences in binding and cleavage frequencies among the recognition sites, may also be obtained. Data for the five recognition sites for the type II restriction endonuclease EcoRI on λ-DNA are presented as a model system. While the roles of the varying fluid velocity and tension along the chain backbone on the measured kinetics remain to be determined, we believe this new method holds promise for a broad range of studies of DNA-protein interactions, including the kinetics of other DNA cleavage processes, the dissociation of a restriction enzyme from the cleaved substrate, and other macromolecular cleavage processes.

  1. Universal quantum dot-based sandwich-like immunoassay strategy for rapid and ultrasensitive detection of small molecules using portable and reusable optofluidic nano-biosensing platform

    International Nuclear Information System (INIS)

    Zhou, Liping; Zhu, Anna; Lou, Xuening; Song, Dan; Yang, Rong; Shi, Hanchang; Long, Feng

    2016-01-01

    A universal sandwich-like immunoassay strategy based on quantum-dots immunoprobe (QD-labeled anti-mouse IgG antibody) was developed for rapid and ultrasensitive detection of small molecules. A portable and reusable optofluidic nano-biosensing platform was applied to investigate the sandwich-like immunoassay mechanism and format of small molecules, as well as the binding kinetics between QD immunoprobe and anti-small molecule antibody. A two-step immunoassay method that involves pre-incubation mixture of different concentration of small molecule and anti-small molecule antibody, and subsequent introduction of QD immunoprobe into the optofluidic cell was conducted for small molecule determination. Compared with the one-step immunoassay method, the two-step immunoassay method can obtain higher fluorescence signal and higher sensitivity index, thus improving the nano-biosensing performance. Based on the proposed strategy, two mode targets, namely, microcystin-LR (MC-LR) and Bisphenol A (BPA) were tested with high sensitivity, rapidity, and ease of use. A higher concentration of small molecules in the sample led to less anti-small molecule antibody bound with antigen-carrier protein conjugate immobilized onto the sensor surface, and less QD immunoprobes bound with anti-small molecule antibody. This phenomenon lowered the fluorescence signal detected by nano-biosensing platform. Under optimal operating conditions, MC-LR and BPA exhibited a limit of detection of 0.003 and 0.04 μg/L, respectively. The LODs were better than those of the indirect competitive immunoassay method for small molecules via Cy5.5-labeled anti-small molecule antibody. The proposed QD-based sandwich-like immunoassay strategy was evaluated in spiked water samples, and showed good recovery, precision and accuracy without complicated sample pretreatments. All these results demonstrate that the new detection strategy could be readily applied to the other trace small molecules in real water samples

  2. Universal quantum dot-based sandwich-like immunoassay strategy for rapid and ultrasensitive detection of small molecules using portable and reusable optofluidic nano-biosensing platform

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Liping; Zhu, Anna; Lou, Xuening; Song, Dan; Yang, Rong [School of Environment and Natural Resources, Renmin University of China, Beijing (China); Shi, Hanchang [School of Environment, Tsinghua University, Beijing (China); Long, Feng, E-mail: longf04@ruc.edu.cn [School of Environment and Natural Resources, Renmin University of China, Beijing (China)

    2016-01-28

    A universal sandwich-like immunoassay strategy based on quantum-dots immunoprobe (QD-labeled anti-mouse IgG antibody) was developed for rapid and ultrasensitive detection of small molecules. A portable and reusable optofluidic nano-biosensing platform was applied to investigate the sandwich-like immunoassay mechanism and format of small molecules, as well as the binding kinetics between QD immunoprobe and anti-small molecule antibody. A two-step immunoassay method that involves pre-incubation mixture of different concentration of small molecule and anti-small molecule antibody, and subsequent introduction of QD immunoprobe into the optofluidic cell was conducted for small molecule determination. Compared with the one-step immunoassay method, the two-step immunoassay method can obtain higher fluorescence signal and higher sensitivity index, thus improving the nano-biosensing performance. Based on the proposed strategy, two mode targets, namely, microcystin-LR (MC-LR) and Bisphenol A (BPA) were tested with high sensitivity, rapidity, and ease of use. A higher concentration of small molecules in the sample led to less anti-small molecule antibody bound with antigen-carrier protein conjugate immobilized onto the sensor surface, and less QD immunoprobes bound with anti-small molecule antibody. This phenomenon lowered the fluorescence signal detected by nano-biosensing platform. Under optimal operating conditions, MC-LR and BPA exhibited a limit of detection of 0.003 and 0.04 μg/L, respectively. The LODs were better than those of the indirect competitive immunoassay method for small molecules via Cy5.5-labeled anti-small molecule antibody. The proposed QD-based sandwich-like immunoassay strategy was evaluated in spiked water samples, and showed good recovery, precision and accuracy without complicated sample pretreatments. All these results demonstrate that the new detection strategy could be readily applied to the other trace small molecules in real water samples

  3. Colorimetric sensor arrays based on pattern recognition for the detection of nitroaromatic molecules

    International Nuclear Information System (INIS)

    Lu, Wei; Dong, Xiao; Qiu, Lili; Yan, Zequn; Meng, Zihui; Xue, Min; He, Xuan; Liu, Xueyong

    2017-01-01

    Graphical abstract: A colorimetric sensor array based on four kinds molecularly imprinted photonic crystal (MIPC) was explored for the selective visual detection of TNT, 2,6-DNT, 2,4-DNT and 4-MNT. The color of individual sensor changed with the increasing concentration of the analytes, and a cross-responsive platform was evaluated by a “radar” pattern. With the assistance of principal component analysis (PCA), a separate response region contained 95.25% of significant characteristics for the detection of nitroaromatics was generated, which also promised high potential for the customized visual detection system of other harmful chemicals. - Highlights: • Nitroaromatics were visually detected by molecularly imprinted photonic crystal. • The adsorption capacity was calculated. • The cross responsive platform of sensor array was established and discussed. • The discrimination capability was promoted by principal component analysis. • This system had high potential to be used in other customed visual detection. - Abstract: This research demonstrated that, in a colorimetric sensor array, 2,4,6-trinitrotoluene (TNT), 2,6-dinitrotoluene (2,6-DNT), 2,4-dinitrotoluene (2,4-DNT) and 4-nitrotoluene (4-MNT) were identifiable through a unique pattern in a qualitative and semi-quantitative manner. The adsorption capacity of the molecularly imprinted colloidal particles (MICs) for their corresponding templates was 0.27 mmol TNT/g, 0.22 mmol 2,6-DNT/g, 0.31 mmol 2,4-DNT/g and 0.16 mmol 4-MNT/g, respectively. Every optical sensor utilized in the arrays contained three-dimensional molecularly imprinted photonic crystal (MIPC) sensor with different imprinted templates. The intelligent materials can display different colors from green to red to 20 mM corresponding nitroaromatics with varying diffraction red shifts of 84 nm (TNT), 46 nm (2,6-DNT), 54 nm (2,4-DNT) and 35 nm (4-MNT), respectively. With the assistance of principal component analysis (PCA) and rational design

  4. Colorimetric sensor arrays based on pattern recognition for the detection of nitroaromatic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei; Dong, Xiao [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing, 100081 (China); Qiu, Lili, E-mail: qiulili@bit.edu.cn [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing, 100081 (China); Yan, Zequn [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing, 100081 (China); Meng, Zihui, E-mail: m_zihui@yahoo.com [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing, 100081 (China); Xue, Min [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing, 100081 (China); He, Xuan; Liu, Xueyong [Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China)

    2017-03-15

    Graphical abstract: A colorimetric sensor array based on four kinds molecularly imprinted photonic crystal (MIPC) was explored for the selective visual detection of TNT, 2,6-DNT, 2,4-DNT and 4-MNT. The color of individual sensor changed with the increasing concentration of the analytes, and a cross-responsive platform was evaluated by a “radar” pattern. With the assistance of principal component analysis (PCA), a separate response region contained 95.25% of significant characteristics for the detection of nitroaromatics was generated, which also promised high potential for the customized visual detection system of other harmful chemicals. - Highlights: • Nitroaromatics were visually detected by molecularly imprinted photonic crystal. • The adsorption capacity was calculated. • The cross responsive platform of sensor array was established and discussed. • The discrimination capability was promoted by principal component analysis. • This system had high potential to be used in other customed visual detection. - Abstract: This research demonstrated that, in a colorimetric sensor array, 2,4,6-trinitrotoluene (TNT), 2,6-dinitrotoluene (2,6-DNT), 2,4-dinitrotoluene (2,4-DNT) and 4-nitrotoluene (4-MNT) were identifiable through a unique pattern in a qualitative and semi-quantitative manner. The adsorption capacity of the molecularly imprinted colloidal particles (MICs) for their corresponding templates was 0.27 mmol TNT/g, 0.22 mmol 2,6-DNT/g, 0.31 mmol 2,4-DNT/g and 0.16 mmol 4-MNT/g, respectively. Every optical sensor utilized in the arrays contained three-dimensional molecularly imprinted photonic crystal (MIPC) sensor with different imprinted templates. The intelligent materials can display different colors from green to red to 20 mM corresponding nitroaromatics with varying diffraction red shifts of 84 nm (TNT), 46 nm (2,6-DNT), 54 nm (2,4-DNT) and 35 nm (4-MNT), respectively. With the assistance of principal component analysis (PCA) and rational design

  5. The detection of small organic molecules based on novel functionalized surface plasmon resonance sensors

    Science.gov (United States)

    Zheng, Rui; Cameron, Brent D.

    2010-02-01

    The objective of this study was to develop rapid, inexpensive, and easily applied in vivo phenotyping strategies for characterizing drug-metabolizing phenotypes with reference to the cytochrome P450 (CYP) enzymes in biological fluids. Therefore, the accurate detection of low concentration of theophylline, which can be used as a probe for cytochrome P450 (CYP450) enzymes (e.g. CYP1A2) activity, could benefit drug-metabolizing studies. In this study, a portable, specific, and sensitive functionalized surface plasmon resonance (SPR) sensor using polyacrylamide molecularly imprinted polymers (MIPs) as the highly specific selector is developed for the detection of low concentration theophylline in the presence of other confounding components, such as, caffeine which has a very similar chemical structure.

  6. Micro-differential thermal analysis detection of adsorbed explosive molecules using microfabricated bridges

    DEFF Research Database (Denmark)

    Senesac, Larry R.; Yi, Dechang; Greve, Anders

    2009-01-01

    Although micromechanical sensors enable chemical vapor sensing with unprecedented sensitivity using variations in mass and stress, obtaining chemical selectivity using the micromechanical response still remains as a crucial challenge. Chemoselectivity in vapor detection using immobilized selective...... layers that rely on weak chemical interactions provides only partial selectivity. Here we show that the very low thermal mass of micromechanical sensors can be used to produce unique responses that can be used for achieving chemical selectivity without losing sensitivity or reversibility. We demonstrate...

  7. Detecting Image Splicing Using Merged Features in Chroma Space

    Directory of Open Access Journals (Sweden)

    Bo Xu

    2014-01-01

    Full Text Available Image splicing is an image editing method to copy a part of an image and paste it onto another image, and it is commonly followed by postprocessing such as local/global blurring, compression, and resizing. To detect this kind of forgery, the image rich models, a feature set successfully used in the steganalysis is evaluated on the splicing image dataset at first, and the dominant submodel is selected as the first kind of feature. The selected feature and the DCT Markov features are used together to detect splicing forgery in the chroma channel, which is convinced effective in splicing detection. The experimental results indicate that the proposed method can detect splicing forgeries with lower error rate compared to the previous literature.

  8. Deep Space Detectives: Searching for Planets Suitable for Life

    Science.gov (United States)

    Pallant, Amy; Damelin, Daniel; Pryputniewicz, Sarah

    2013-01-01

    This article describes the High-Adventure Science curriculum unit "Is There Life in Space?" This free online investigation, developed by The Concord Consortium, helps students see how scientists use modern tools to locate planets around distant stars and explore the probability of finding extraterrestrial life. This innovative curriculum…

  9. Unprivileged Black-Box Detection of User-space Keyloggers

    NARCIS (Netherlands)

    Ortolani, S.; Giuffrida, C.; Crispo, B.

    2012-01-01

    Software keyloggers are a fast growing class of invasive software often used to harvest confidential information. One of the main reasons for this rapid growth is the possibility for unprivileged programs running in user space to eavesdrop and record all the keystrokes typed by the users of a

  10. The influence of interdental spacing on the detection of proximal caries lesions in primary teeth

    Directory of Open Access Journals (Sweden)

    Tatiane Fernandes Novaes

    2012-08-01

    Full Text Available The aim of this study was to investigate the influence of interdental spacing on the performance of proximal caries detection methods in primary molars. In addition, aspects related to temporary tooth separation with orthodontic separators were evaluated. The proximal spaces between the posterior primary teeth (n = 344 of 76 children (4-12 years old were evaluated before and after temporary separation. Stainless steel strips with different standardized thicknesses were used to measure the presence of biological spacing and the spacing obtained after temporary separation with orthodontic rubber rings. First, the presence of proximal caries lesions was assessed by visual inspection, bitewing radiographs and a pen-type laser fluorescence device (DIAGNOdent pen. Visual inspection after temporary separation with separators was the reference standard method in checking the actual presence of caries. Multilevel analyses were performed considering different outcomes: the performance of the methods in detecting caries lesions and the spacing after temporary separation. The spacing did not influence the performance of the caries detection methods. The maximum spacing obtained with temporary tooth separation was 0.80 mm (mean ± standard deviation = 0.46 ± 0.13 mm. The temporary separation was more effective in the upper arch and less effective when an initial biological interdental spacing was present. The biological interdental spacing does not influence the performance of proximal caries detection methods in primary molars, and temporary tooth separation provides spacing narrower than 1.0 mm.

  11. The influence of interdental spacing on the detection of proximal caries lesions in primary teeth.

    Science.gov (United States)

    Novaes, Tatiane Fernandes; Matos, Ronilza; Celiberti, Paula; Braga, Mariana Minatel; Mendes, Fausto Medeiros

    2012-01-01

    The aim of this study was to investigate the influence of interdental spacing on the performance of proximal caries detection methods in primary molars. In addition, aspects related to temporary tooth separation with orthodontic separators were evaluated. The proximal spaces between the posterior primary teeth (n = 344) of 76 children (4-12 years old) were evaluated before and after temporary separation. Stainless steel strips with different standardized thicknesses were used to measure the presence of biological spacing and the spacing obtained after temporary separation with orthodontic rubber rings. First, the presence of proximal caries lesions was assessed by visual inspection, bitewing radiographs and a pen-type laser fluorescence device (DIAGNOdent pen). Visual inspection after temporary separation with separators was the reference standard method in checking the actual presence of caries. Multilevel analyses were performed considering different outcomes: the performance of the methods in detecting caries lesions and the spacing after temporary separation. The spacing did not influence the performance of the caries detection methods. The maximum spacing obtained with temporary tooth separation was 0.80 mm (mean ± standard deviation = 0.46 ± 0.13 mm). The temporary separation was more effective in the upper arch and less effective when an initial biological interdental spacing was present. The biological interdental spacing does not influence the performance of proximal caries detection methods in primary molars, and temporary tooth separation provides spacing narrower than 1.0 mm.

  12. Rapid identification of bio-molecules applied for detection of biosecurity agents using rolling circle amplification.

    Directory of Open Access Journals (Sweden)

    Jenny Göransson

    Full Text Available Detection and identification of pathogens in environmental samples for biosecurity applications are challenging due to the strict requirements on specificity, sensitivity and time. We have developed a concept for quick, specific and sensitive pathogen identification in environmental samples. Target identification is realized by padlock- and proximity probing, and reacted probes are amplified by RCA (rolling-circle amplification. The individual RCA products are labeled by fluorescence and enumerated by an instrument, developed for sensitive and rapid digital analysis. The concept is demonstrated by identification of simili biowarfare agents for bacteria (Escherichia coli and Pantoea agglomerans and spores (Bacillus atrophaeus released in field.

  13. Biomimetic Receptors for Bioanalyte Detection by Quartz Crystal Microbalances — From Molecules to Cells

    Directory of Open Access Journals (Sweden)

    Usman Latif

    2014-12-01

    Full Text Available A universal label-free detection of bioanalytes can be performed with biomimetic quartz crystal microbalance (QCM coatings prepared by imprinting strategies. Bulk imprinting was used to detect the endocrine disrupting chemicals (EDCs known as estradiols. The estrogen 17β-estradiol is one of the most potent EDCs, even at very low concentrations. A highly sensitive, selective and robust QCM sensor was fabricated for real time monitoring of 17β-estradiol in water samples by using molecular imprinted polyurethane. Optimization of porogen (pyrene and cross-linker (phloroglucinol levels leads to improved sensitivity, selectivity and response time of the estradiol sensor. Surface imprinting of polyurethane as sensor coating also allowed us to generate interaction sites for the selective recognition of bacteria, even in a very complex mixture of interfering compounds, while they were growing from their spores in nutrient solution. A double molecular imprinting approach was followed to transfer the geometrical features of natural bacteria onto the synthetic polymer to generate biomimetic bacteria. The use of biomimetic bacteria as template makes it possible to prepare multiple sensor coatings with similar sensitivity and selectivity. Thus, cell typing, e.g., differentiation of bacteria strains, bacteria growth profile and extent of their nutrition, can be monitored by biomimetic mass sensors. Obviously, this leads to controlled cell growth in bioreactors.

  14. Thermographic Leak Detection of the Space Shuttle Main Engine Nozzle

    Science.gov (United States)

    Walker, James L.; Russell, Samuel S.

    1999-01-01

    The Space Shuttle Main Engines Nozzles consist of over one thousand tapered Inconel coolant tubes brazed to a stainless steel structural jacket. Liquid Hydrogen flows through the tubing, from the aft to forward end of the nozzle, under high pressure to maintain a thermal balance between the rocket exhaust and the nozzle wall. Three potential problems occur within the SSME nozzle coolant tubes as a result of manufacturing anomalies and the highly volatile service environment including poor or incomplete bonding of the tubes to the structural jacket, cold wall leaks and hot wall leaks. Of these conditions the identification of cold wall leaks has been the most problematic. The methods and results presented in this summary addresses the thermographic identification of cold wall "interstitial" leaks between the structural jacket and coolant tubes of the Space Shuttle Main Engines Nozzles.

  15. Zika Virus Escapes NK Cell Detection by Upregulating Major Histocompatibility Complex Class I Molecules.

    Science.gov (United States)

    Glasner, Ariella; Oiknine-Djian, Esther; Weisblum, Yiska; Diab, Mohammad; Panet, Amos; Wolf, Dana G; Mandelboim, Ofer

    2017-11-15

    infection is largely unknown. Here we demonstrate that Zika virus infection is almost undetected by NK cells, as evidenced by the fact that the expression of activating ligands for NK cells is not induced following Zika infection. We identified a mechanism whereby Zika virus sensing via the RIGI-IRF3 pathway resulted in IFN-β-mediated upregulation of MHC-I molecules and inhibition of NK cell activity. Countering MHC class I upregulation and boosting NK cell activity may be employed as prophylactic measures to combat Zika virus infection. Copyright © 2017 American Society for Microbiology.

  16. A Fluorogenic Probe for the Catalyst-Free Detection of Azide-Tagged Molecules

    Science.gov (United States)

    Friscourt, Frédéric; Fahrni, Christoph J.; Boons, Geert-Jan

    2012-01-01

    Fluorogenic reactions in which non- or weakly-fluorescent reagents produce highly fluorescent products can be exploited to detect a broad range of compounds including biomolecules and materials. We describe a modified dibenzocyclooctyne that under catalyst-free conditions undergoes fast strain-promoted cycloadditions with azides to yield strongly fluorescent triazoles. The cycloaddition products are more than 1000-fold brighter compared to the starting cyclooctyne, exhibit large Stokes shift, and can be excited above 350 nm, which is required for many applications. Quantum mechanical calculations indicate that the fluorescence increase upon triazole formation is due to large differences in oscillator strengths of the S0 S1 transitions in the planar C2v-symmetric starting material compared to the symmetry-broken and non-planar cycloaddition products. The new fluorogenic probe was successfully employed for labeling of proteins modified by an azide moiety. PMID:23095037

  17. Quantitative carbon detector for enhanced detection of molecules in foods, pharmaceuticals, cosmetics, flavors, and fuels.

    Science.gov (United States)

    Beach, Connor A; Krumm, Christoph; Spanjers, Charles S; Maduskar, Saurabh; Jones, Andrew J; Dauenhauer, Paul J

    2016-03-07

    Analysis of trace compounds, such as pesticides and other contaminants, within consumer products, fuels, and the environment requires quantification of increasingly complex mixtures of difficult-to-quantify compounds. Many compounds of interest are non-volatile and exhibit poor response in current gas chromatography and flame ionization systems. Here we show the reaction of trimethylsilylated chemical analytes to methane using a quantitative carbon detector (QCD; the Polyarc™ reactor) within a gas chromatograph (GC), thereby enabling enhanced detection (up to 10×) of highly functionalized compounds including carbohydrates, acids, drugs, flavorants, and pesticides. Analysis of a complex mixture of compounds shows that the GC-QCD method exhibits faster and more accurate analysis of complex mixtures commonly encountered in everyday products and the environment.

  18. Analysis of gate underlap channel double gate MOS transistor for electrical detection of bio-molecules

    Science.gov (United States)

    Ajay; Narang, Rakhi; Saxena, Manoj; Gupta, Mridula

    2015-12-01

    In this paper, an analytical model for gate drain underlap channel Double-Gate Metal-Oxide-Semiconductor Field-Effect Transistor (DG-MOSFET) for label free electrical detection of biomolecules has been proposed. The conformal mapping technique has been used to derive the expressions for surface potential, lateral electric field, energy bands (i.e. conduction and valence band) and threshold voltage (Vth). Subsequently a full drain current model to analyze the sensitivity of the biosensor has been developed. The shift in the threshold voltage and drain current (after the biomolecules interaction with the gate underlap channel region of the MOS transistor) has been used as a sensing metric. All the characteristic trends have been verified through ATLAS (SILVACO) device simulation results.

  19. Construction of a reference plasmid molecule containing eight targets for the detection of genetically modified crops.

    Science.gov (United States)

    Wang, Xiumin; Teng, Da; Yang, Yalin; Tian, Fang; Guan, Qingfeng; Wang, Jianhua

    2011-04-01

    A standard plasmid containing eight targets was developed for quantitative detection of genetically modified (GM) soybeans and cotton. These eight targets were joined in tandem to form the pTLE8 plasmid with a length of 3,680 bp. This plasmid contains part of the endogenous soybean Lec1 gene, the Cauliflower mosaic virus (CaMV) 35S promoter, the Agrobacterium tumefaciens nopaline synthase (NOS) terminator, the PAT gene of the soybean line A2704-12, the event-specific 5'-junction region of Roundup-Ready Soya (RRS, 35SG), the Cry1A(c) gene from Bacillus thuringiensis (Bt), the endogenous cotton Sad1 gene, and a part of RRS EPSPS gene. The PCR efficiencies with pTLE8 as a calibrator ranged from 99.4% to 100.2% for the standard curves of the RRS EPSPS gene and the taxon-specific Lec1 gene (R(2)≥0.996). The limits of detection and quantification were nine and 15 copies, respectively. The standard deviation (SD) and relative standard deviation (RSD) values of repeatability were from 0.09 to 0.52 and from 0.28% to 2.11%, and those for reproducibility were from 0.12 to 1.15 and 0.42% to 3.85%, respectively. The average conversion factor (Cf) for the CRMs RRS quantification was 0.91. The RSD of the mean values for known samples ranged from 3.09% to 18.53%, and the biases were from 0.5% to 40%. These results show that our method using the pTLE8 plasmid as a reference material (RM) is reliable and feasible in the identification of GM soybeans, thus paving the way for the establishment of identification management systems for various products containing GMO components. © Springer-Verlag 2011

  20. Small-molecule fluorophores to detect cell-state switching in the context of high-throughput screening.

    Science.gov (United States)

    Wagner, Bridget K; Carrinski, Hyman A; Ahn, Young-Hoon; Kim, Yun Kyung; Gilbert, Tamara J; Fomina, Dina A; Schreiber, Stuart L; Chang, Young-Tae; Clemons, Paul A

    2008-04-02

    A small molecule capable of distinguishing the distinct states resulting from cellular differentiation would be of enormous value, for example, in efforts aimed at regenerative medicine. We screened a collection of fluorescent small molecules for the ability to distinguish the differentiated state of a mouse skeletal muscle cell line. High-throughput fluorescence-based screening of C2C12 myoblasts and myotubes resulted in the identification of six compounds with the desired selectivity, which was confirmed by high-content screening in the same cell states. The compound that resulted in the greatest fluorescence intensity difference between the cell states was used as the screening agent in a pilot screen of 84 kinase inhibitors, each present in four doses, for inhibition of myogenesis. Of the kinase inhibitors, 17 resulted in reduction of fluorescence at one or more concentrations; among the "hits" included known inhibitors of myogenesis, confirming that this compound is capable of detecting the differentiated myotube state. We suggest that the strategy of screening for screening agents reported here may be extended more broadly in the future.

  1. Simultaneous detection of mRNA and protein in single cells using immunofluorescence-combined single-molecule RNA FISH.

    Science.gov (United States)

    Kochan, Jakub; Wawro, Mateusz; Kasza, Aneta

    2015-10-01

    Although the concept of combining immunofluorescence (IF) with single-molecule RNA fluorescence in situ hybridization (smRNA FISH) seems obvious, the specific materials used during IF and smRNA FISH make it difficult to perform these procedures simultaneously on the same specimen. Even though there are reports where IF and smRNA FISH were combined with success, these were insufficient in terms of signal intensities, staining patterns, and GFP-compatibility, and a detailed exploration of the various factors that influence IF and smRNA FISH outcome has not been published yet. Here, we report a detailed study of conditions and reagents used in classic IF and smRNA FISH that allowed us to establish an easy, robust, and GFP-compatible procedure. Our protocol enables simultaneous detection of mRNA and protein quantity as well as the subcellular distribution of these molecules in single cells by combining an RNase-free modification of the IF technique and the more recent smRNA FISH method. Using this procedure, we have shown the direct interaction of RNase MCPIP1 with IL-6 mRNA. We also demonstrate the use of our protocol in heterogeneous cell population analysis, revealing cell-to-cell differences in mRNA and protein content.

  2. Development of a graphene oxide-based assay for the sequence-specific detection of double-stranded DNA molecules.

    Directory of Open Access Journals (Sweden)

    Anna Maria Giuliodori

    Full Text Available Graphene oxide (GO is a promising material for the development of cost-effective detection systems. In this work, we have devised a simple and rapid GO-based method for the sequence-specific identification of DNA molecules generated by PCR amplification. The csp genes of Escherichia coli, which share a high degree of sequence identity, were selected as paradigm DNA templates. All tested csp genes were amplified with unlabelled primers, which can be rapidly removed at the end of the PCR taking advantage of the preferential binding to GO of single-stranded versus duplex DNA molecules. The amplified DNAs (targets were heat-denatured and hybridized to a fluorescently-labelled single strand oligonucleotide (probe, which recognizes a region of the target DNAs displaying sequence variability. This interaction is extremely specific, taking place with high efficiency only when target and probe show perfect or near perfect matching. Upon GO addition, the unbound fraction of the probe was captured and its fluorescence quenched by the GO's molecular properties. On the other hand, the probe-target complexes remained in solution and emitted a fluorescent signal whose intensity was related to their degree of complementarity.

  3. Direct Determination of a Small-Molecule Drug, Valproic Acid, by an Electrically-Detected Microcantilever Biosensor for Personalized Diagnostics

    Directory of Open Access Journals (Sweden)

    Long-Sun Huang

    2015-01-01

    Full Text Available Direct, small-molecule determination of the antiepileptic drug, valproic acid, was investigated by a label-free, nanomechanical biosensor. Valproic acid has long been used as an antiepileptic medication, which is administered through therapeutic drug monitoring and has a narrow therapeutic dosage range of 50–100 μg·mL−1 in blood or serum. Unlike labeled and clinically-used measurement techniques, the label-free, electrical detection microcantilever biosensor can be miniaturized and simplified for use in portable or hand-held point-of-care platforms or personal diagnostic tools. A micromachined microcantilever sensor was packaged into the micro-channel of a fluidic system. The measurement of the antiepileptic drug, valproic acid, in phosphate-buffered saline and serum used a single free-standing, piezoresistive microcantilever biosensor in a thermally-controlled system. The measured surface stresses showed a profile over a concentration range of 50–500 μg·mL−1, which covered the clinically therapeutic range of 50–100 μg·mL−1. The estimated limit of detection (LOD was calculated to be 45 μg·mL−1, and the binding affinity between the drug and the antibody was measured at around 90 ± 21 μg·mL−1. Lastly, the results of the proposed device showed a similar profile in valproic acid drug detection with those of the clinically-used fluorescence polarization immunoassay.

  4. A Novel Approach of Sensitive Infrared Signal Detection for Space Applications

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop an innovative frequency up-conversion device that will efficiently convert the infrared signals into visible/near-infrared signals to enable detection of...

  5. Detection of wood cell wall porosity using small carbohydrate molecules and confocal fluorescence microscopy.

    Science.gov (United States)

    Donaldson, L A; Kroese, H W; Hill, S J; Franich, R A

    2015-09-01

    A novel approach to nanoscale detection of cell wall porosity using confocal fluorescence microscopy is described. Infiltration of cell walls with a range of nitrophenyl-substituted carbohydrates of different molecular weights was assessed by measuring changes in the intensity of lignin fluorescence, in response to the quenching effect of the 4-nitrophenyl group. The following carbohydrates were used in order of increasing molecular weight; 4-nitrophenyl β-D-glucopyrano-side (monosaccharide), 4-nitrophenyl β-D-lactopyranoside (disaccharide), 2-chloro-4-nitrophenyl β-D-maltotrioside (trisaccharide), and 4-nitrophenyl α-D-maltopentaoside (pentasaccharide). This technique was used to compare cell wall porosity in wood which had been dewatered to 40% moisture content using supercritical CO2, where cell walls remain fully hydrated, with kiln dried wood equilibrated to 12% moisture content. Infiltration of cell walls as measured by fluorescence quenching, was found to decrease with increasing molecular weight, with the pentasaccharide being significantly excluded compared to the monosaccharide. Porosity experiments were performed on blocks and sections to assess differences in cell wall accessibility. Dewatered and kiln dried wood infiltrated as blocks showed similar results, but greater infiltration was achieved by using sections, indicating that not all pores were easily accessible by infiltration from the lumen surface. In wood blocks infiltrated with 4-nitrophenyl α-D-maltopentaoside, quenching of the secondary wall was quite variable, especially in kiln dried wood, indicating limited connectivity of pores accessible from the lumen surface. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  6. Computational prediction of the spectroscopic parameters of methanediol, an elusive molecule for interstellar detection

    Energy Technology Data Exchange (ETDEWEB)

    Barrientos, Carmen; Redondo, Pilar; Largo, Antonio [Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, Campus Miguel Delibes, Paseo de Belén 7, E-47011 Valladolid (Spain); Martínez, Henar, E-mail: alargo@qf.uva.es [Departamento de Química Orgánica, Escuela de Ingenierías Industriales, Universidad de Valladolid, Campus Esgueva, Paseo del Cauce 59, E-47011 Valladolid (Spain)

    2014-04-01

    The molecular structure of methanediol has been investigated by means of quantum chemical calculations. Two conformers, corresponding to C{sub 2} and C {sub s} symmetries, respectively, were considered. The C{sub 2} conformer is found to lie about 1.7 (at 298 K) or 2.3 (at 0 K) kcal mol{sup –1} below the C {sub s} conformer. Predictions for their rotational constants, vibrational frequencies, IR intensities, and dipole moments have been provided. The lowest-lying isomer has a very low dipole moment, around 0.03 D, whereas the C {sub s} conformer has a relatively high dipole moment, namely, 2.7 D. The barrier for the C {sub s} →C{sub 2} process is predicted to be around 0.7-1 kcal mol{sup –1}. Based on the energetic results the proportion of the C{sub s} conformer is likely to be negligible under low temperature conditions, such as in the interstellar medium. Therefore, it is predicted that detection by radioastronomy of methanediol would be rather unlikely.

  7. EXOTIC METAL MOLECULES IN OXYGEN-RICH ENVELOPES: DETECTION OF AlOH (X1Σ+) IN VY CANIS MAJORIS

    International Nuclear Information System (INIS)

    Tenenbaum, E. D.; Ziurys, L. M.

    2010-01-01

    A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s -1 , as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H 2 was found to be ∼1 x 10 -7 for a source size of 0.26'' or 22 R * . In contrast, AlCl was not detected with f ≤ 5 x 10 -8 . AlOH is likely formed just beyond the photosphere via thermodynamic equilibrium chemistry and then disappears due to dust condensation. The AlOH/AlO abundance ratio found in VY CMa is ∼17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

  8. Ion-induced stacking of photosensitizer molecules can remarkably affect the luminescence detection of singlet oxygen in Candida albicans cells

    Science.gov (United States)

    Felgenträger, Ariane; Gonzales, Fernanda Pereira; Maisch, Tim; Bäumler, Wolfgang

    2013-04-01

    Singlet oxygen (O21) is an important reactive intermediate in photodynamic reactions, particularly in antimicrobial PDT (aPDT). The detection of O21 luminescence is frequently used to elucidate the role of O21 in various environments, particularly in microorganisms and human cells. When incubating the fungus, Candida albicans, with porphyrins XF73 (5,15-bis-[4-(3-Trimethylammonio-propyloxy)-phenyl]-porphyrin) or TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)-porphyrin tetra(p-toluenesulfonate)), the O21 luminescence signals were excellent for TMPyP. In case of XF73, the signals showed strange rise and decay times. Thus, O21 generation of XF73 was investigated and compared with TMPyP. Absorption spectroscopy of XF73 showed a change in absorption cross section when there was a change in the concentration from 1×10-6 M to 1×10-3 M indicating an aggregation process. The addition of phosphate buffered saline (PBS) substantially changed O21 luminescence in XF73 solution. Detailed experiments provided evidence that the PBS constituents NaCl and KCl caused the change of O21 luminescence. The results also indicate that Cl- ions may cause aggregation of XF73 molecules, which in turn enhances self-quenching of O21 via photosensitizer molecules. These results show that some ions, e.g., those present in cells in vitro or added by PBS, can considerably affect the detection and the interpretation of time-resolved luminescence signals of O21, particularly in in vitro and in vivo. These effects should be considered for any other photosensitizer used in photodynamic processes.

  9. Auditory Perception in an Open Space: Detection and Recognition

    Science.gov (United States)

    2015-06-01

    park traffic noise made by cars with gasoline engines . They reported that 9 out of 10 of their listeners could detect the diesel engine at Abouchacra...Human Factors. 1986;28(1):23–29. Lamancusa JS. Outdoor sound propagation. Noise Control. ME 458: Engineering Noise Control. State College (PA): Penn...ambient noise . Aberdeen Proving Ground (MD): Army Human Engineering Laboratory (US); 1965. HEL Letter Report 12. Morse PM, Ingård KU. Theoretical

  10. Extreme Water Deficit in Brazil Detected from Space

    Science.gov (United States)

    Vieira Getirana

    2016-01-01

    Extreme droughts have caused significant socioeconomic and environmental damage worldwide. In Brazil, ineffective energy development and water management policies have magnified the impacts of recent severe droughts, which include massive agricultural losses, water supply restrictions, and energy rationing. Spaceborne remote sensing data advance our understanding of the spatiotemporal variability of large-scale droughts and enhance the detection and monitoring of extreme water-related events. In this study, data derived from the Gravity Recovery and Climate Experiment (GRACE) mission are used to detect and quantify an extended major drought over eastern Brazil and provide estimates of impacted areas and region-specific water deficits. Two structural breakpoint detection methods were applied to time series of GRACE-based terrestrial water storage anomalies (TWSA), determining when two abrupt changes occurred. One, in particular, defines the beginning of the current drought. Using TWSA, a water loss rate of 26.1 cmyr21 over southeastern Brazil was detected from 2012 to 2015. Based on analysis of Global Land Data Assimilation System(GLDAS) outputs, the extreme drought is mostly related to lower-than-usual precipitation rates, resulting in high soil moisture depletion and lower-than-usual rates of evapotranspiration. A reduction of 2023 of precipitation over an extended period of 3 years is enough to raise serious water scarcity conditions in the country. Correlations between monthly time series of both grid-based TWSA and ground-based water storage measurements at 16 reservoirs located within southeastern Brazil varied from 0.42 to 0.82. Differences are mainly explained by reservoir sizes and proximity to the drought nucleus.

  11. Planetary-scale surface water detection from space

    Science.gov (United States)

    Donchyts, G.; Baart, F.; Winsemius, H.; Gorelick, N.

    2017-12-01

    Accurate, efficient and high-resolution methods of surface water detection are needed for a better water management. Datasets on surface water extent and dynamics are crucial for a better understanding of natural and human-made processes, and as an input data for hydrological and hydraulic models. In spite of considerable progress in the harmonization of freely available satellite data, producing accurate and efficient higher-level surface water data products remains very challenging. This presentation will provide an overview of existing methods for surface water extent and change detection from multitemporal and multi-sensor satellite imagery. An algorithm to detect surface water changes from multi-temporal satellite imagery will be demonstrated as well as its open-source implementation (http://aqua-monitor.deltares.nl). This algorithm was used to estimate global surface water changes at high spatial resolution. These changes include climate change, land reclamation, reservoir construction/decommissioning, erosion/accretion, and many other. This presentation will demonstrate how open satellite data and open platforms such as Google Earth Engine have helped with this research.

  12. Asteroid Detection Results Using the Space Surveillance Telescope

    Science.gov (United States)

    Ruprecht, Jessica D.; Ushomirsky, Gregory; Woods, Deborah F.; Viggh, Herbert E. M.; Varey, Jacob; Cornell, Mark E.; Stokes, Grant

    2015-11-01

    From 1998-2013, MIT Lincoln Laboratory operated a highly successful near-Earth asteroid search program using two 1-m optical telescopes located at the MIT Lincoln Laboratory Experimental Test Site (ETS) in Socorro, N.M. In 2014, the Lincoln Near-Earth Asteroid Research (LINEAR) program successfully transitioned operations from the two 1-m telescopes to the 3.5-m Space Surveillance Telescope (SST) located at Atom Site on White Sands Missile Range, N.M. This paper provides a summary of first-year performance and results for the LINEAR program with SST and provides an update on recent improvements to the moving-object pipeline architecture that increase utility of SST data for NEO discovery and improve sensitivity to fast-moving objects. Ruprecht et al. (2014) made predictions for SST NEO search productivity as a function of population model. This paper assesses the NEO search performance of SST in the first 1.5 years of operation and compares results to model predictions.This work is sponsored by the Defense Advanced Research Projects Agency and the National Aeronautics and Space Administration under Air Force Contract #FA8721-05-C-0002. The views, opinions, and/or findings contained in this article/presentation are those of the authors / presenters and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government. Distribution Statement A: Approved for public release, distribution unlimited.

  13. Detection of posture-induced constriction of the cervical cerebrospinal fluid space by scintiscanning

    Energy Technology Data Exchange (ETDEWEB)

    Otto, H.J. (Medizinische Akademie, Magdeburg (German Democratic Republic). Radiologische Klinik); Koch, R.D.; Krause, P. (Medizinische Akademie, Magdeburg (German Democratic Republic). Nervenklinik)

    1983-06-01

    Scintiscanning of the cervical cerebrospinal fluid space at maximum ante- and retroflexion in 24 patients revealed the method to be recommended for use in the case of cervical myelopathy when the polymorphous early symptoms appear and before myelography as well as for follow-up examination. The detection of posture-induced constriction of the lumen provides additional information and increases the sensitivity considerably because, particularly during retroflexion, minor inflammatory reactions lead to scintigraphically detectable reduction in the liquor space.

  14. Dynamical 3-Space: Gravitational Wave Detection and the Shnoll Effect

    Directory of Open Access Journals (Sweden)

    Rothall D. P.

    2013-10-01

    Full Text Available Shnoll has investigated the non-Poisson scatter of rate measurements in various phenomena such as biological and chemical reactions, radioactive decay, photodiode current leakage and germanium semiconductor noise, and attributed the scatter to cosmophysical factors. While Shnoll didn’t pinpoint the nature of the cosmophysical factors the Process Physics model of reality leads to a description of space, which is dynamic and fractal and exhibits reverberation eects, and which oers an explanation for the scattering anomaly. The work presented here shows a new way of generating the eects Shnoll discovered, through studying the phase dierence of RF EM waves travelling through a dual coaxial cable Gravitational Wave Detector experiment.

  15. Light Detection and Ranging (LIDAR) From Space - Laser Altimeters

    Science.gov (United States)

    Sun, Xiaoli

    2016-01-01

    Light detection and ranging, or lidar, is like radar but atoptical wavelengths. The principle of operation and theirapplications in remote sensing are similar. Lidars havemany advantages over radars in instrument designs andapplications because of the much shorter laser wavelengthsand narrower beams. The lidar transmitters and receiveroptics are much smaller than radar antenna dishes. Thespatial resolution of lidar measurement is much finer thanthat of radar because of the much smaller footprint size onground. Lidar measurements usually give a better temporalresolution because the laser pulses can be much narrowerthan radio frequency (RF) signals. The major limitation oflidar is the ability to penetrate clouds and ground surfaces.

  16. The formation of urea in space. I. Ion-molecule, neutral-neutral, and radical gas-phase reactions

    Science.gov (United States)

    Brigiano, Flavio Siro; Jeanvoine, Yannick; Largo, Antonio; Spezia, Riccardo

    2018-02-01

    Context. Many organic molecules have been observed in the interstellar medium thanks to advances in radioastronomy, and very recently the presence of urea was also suggested. While those molecules were observed, it is not clear what the mechanisms responsible to their formation are. In fact, if gas-phase reactions are responsible, they should occur through barrierless mechanisms (or with very low barriers). In the past, mechanisms for the formation of different organic molecules were studied, providing only in a few cases energetic conditions favorable to a synthesis at very low temperature. A particularly intriguing class of such molecules are those containing one N-C-O peptide bond, which could be a building block for the formation of biological molecules. Urea is a particular case because two nitrogen atoms are linked to the C-O moiety. Thus, motivated also by the recent tentative observation of urea, we have considered the synthetic pathways responsible to its formation. Aims: We have studied the possibility of forming urea in the gas phase via different kinds of bi-molecular reactions: ion-molecule, neutral, and radical. In particular we have focused on the activation energy of these reactions in order to find possible reactants that could be responsible for to barrierless (or very low energy) pathways. Methods: We have used very accurate, highly correlated quantum chemistry calculations to locate and characterize the reaction pathways in terms of minima and transition states connecting reactants to products. Results: Most of the reactions considered have an activation energy that is too high; but the ion-molecule reaction between NH2OHNH2OH2+ and formamide is not too high. These reactants could be responsible not only for the formation of urea but also of isocyanic acid, which is an organic molecule also observed in the interstellar medium.

  17. Equipartition of energy in a one-dimensional model of diatomic molecules. II. Maximal Lyapunov exponent and phase-space trajectory separation

    International Nuclear Information System (INIS)

    Monge, A.; Cohen, E.G.D.; Erpenbeck, J.J.

    1991-01-01

    The Lyapunov instability is studied numerically for a one-dimensional model of diatomic molecules with harmonic intramolecular and hard intermolecular interactions. Previous results are extended to characterize the equipartition regime in terms of the two parameters of the system, the number of molecules n and the vibrational frequency ω. When the system is in equipartition, we find the existence of a thermodynamic limit for the maximal Lyapunov exponent and a power-law behavior ω α , in analogy with the Fermi-Pasta-Ulam model. The separation of trajectories in phase space, investigated by considering the time dependence of the distance of initially close trajectories and by averaging over the phase space, is related to the maximal Lyapunov exponent and shown to be an alternative way to compute it when n is not too large. Multiple-precision arithmetic analysis for the model and its link to Lyapunov instability are also discussed

  18. Tunable PIE and synchronized gating detections by FastFLIM for quantitative microscopy measurements of fast dynamics of single molecules

    Science.gov (United States)

    Sun, Yuansheng; Coskun, Ulas; Ferreon, Allan Chris; Barbieri, Beniamino; Liao, Shih-Chu Jeff

    2016-03-01

    The crosstalk between two fluorescent species causes problems in fluorescence microscopy imaging, especially for quantitative measurements such as co-localization, Förster resonance energy transfer (FRET), fluorescence cross correlation spectroscopy (FCCS). In laser scanning confocal microscopy, the lasers can be switched on and off by acousto-optic tunable filters (AOTF) in the microsecond scale for alternative line scanning in order to avoid the crosstalk while minimizing the time delay between two lasers on the same pixel location. In contrast, the pulsed interleaved excitation (PIE) technique synchronizes two pulsed lasers of different wavelengths in the nanosecond scale to enable measuring superfast dynamics of two fluorescent species simultaneously and yet quantitatively without the crosstalk contamination. This feature is critical for many cell biology applications, e.g. accurate determination of stoichiometry in FRET measurements for studying protein-protein interactions or cell signal events, detection of weaker bindings in FCCS by eliminating the false cross correlation due to the crosstalk. The PIE has been used with the time correlated single photon counting (TCSPC) electronics. Here, we describe a novel PIE development using the digital frequency domain (DFD) technique -- FastFLIM, which provides tunable PIE setups and synchronized gating detections, tailored and optimized to specific applications. A few PIE setups by FastFLIM and measurement examples are described. Combined with the sensitivity of Alba and Q2 systems, the PIE allowed us to quantitatively measure the fast dynamics of single molecules.

  19. Research on capability of detecting ballistic missile by near space infrared system

    Science.gov (United States)

    Lu, Li; Sheng, Wen; Jiang, Wei; Jiang, Feng

    2018-01-01

    The infrared detection technology of ballistic missile based on near space platform can effectively make up the shortcomings of high-cost of traditional early warning satellites and the limited earth curvature of ground-based early warning radar. In terms of target detection capability, aiming at the problem that the formula of the action distance based on contrast performance ignores the background emissivity in the calculation process and the formula is only valid for the monochromatic light, an improved formula of the detecting range based on contrast performance is proposed. The near space infrared imaging system parameters are introduced, the expression of the contrastive action distance formula based on the target detection of the near space platform is deduced. The detection range of the near space infrared system for the booster stage ballistic missile skin, the tail nozzle and the tail flame is calculated. The simulation results show that the near-space infrared system has the best effect on the detection of tail-flame radiation.

  20. Object detection with DoG scale-space: a multiple kernel learning approach.

    Science.gov (United States)

    Nilufar, Sharmin; Ray, Nilanjan; Zhang, Hong

    2012-08-01

    Difference of Gaussians (DoG) scale-space for an image is a significant way to generate features for object detection and classification. While applying DoG scale-space features for object detection/classification, we face two inevitable issues: dealing with high dimensional data and selecting/weighting of proper scales. The scale selection process is mostly ad-hoc to date. In this paper, we propose a multiple kernel learning (MKL) method for both DoG scale selection/weighting and dealing with high dimensional scale-space data. We design a novel shift invariant kernel function for DoG scale-space. To select only the useful scales in the DoG scale-space, a novel framework of MKL is also proposed. We utilize a 1-norm support vector machine (SVM) in the MKL optimization problem for sparse weighting of scales from DoG scale-space. The optimized data-dependent kernel accommodates only a few scales that are most discriminatory according to the large margin principle. With a 2-norm SVM this learned kernel is applied to a challenging detection problem in oil sand mining: to detect large lumps in oil sand videos. We tested our method on several challenging oil sand data sets. Our method yields encouraging results on these difficult-to-process images and compares favorably against other popular multiple kernel methods.

  1. Efficient and automatic image reduction framework for space debris detection based on GPU technology

    Science.gov (United States)

    Diprima, Francesco; Santoni, Fabio; Piergentili, Fabrizio; Fortunato, Vito; Abbattista, Cristoforo; Amoruso, Leonardo

    2018-04-01

    In the last years, the increasing number of space debris has triggered the need of a distributed monitoring system for the prevention of possible space collisions. Space surveillance based on ground telescope allows the monitoring of the traffic of the Resident Space Objects (RSOs) in the Earth orbit. This space debris surveillance has several applications such as orbit prediction and conjunction assessment. In this paper is proposed an optimized and performance-oriented pipeline for sources extraction intended to the automatic detection of space debris in optical data. The detection method is based on the morphological operations and Hough Transform for lines. Near real-time detection is obtained using General Purpose computing on Graphics Processing Units (GPGPU). The high degree of processing parallelism provided by GPGPU allows to split data analysis over thousands of threads in order to process big datasets with a limited computational time. The implementation has been tested on a large and heterogeneous images data set, containing both imaging satellites from different orbit ranges and multiple observation modes (i.e. sidereal and object tracking). These images were taken during an observation campaign performed from the EQUO (EQUatorial Observatory) observatory settled at the Broglio Space Center (BSC) in Kenya, which is part of the ASI-Sapienza Agreement.

  2. Research Progress of Space-Time Adaptive Detection for Airborne Radar

    Directory of Open Access Journals (Sweden)

    Wang Yong-liang

    2014-04-01

    Full Text Available Compared with Space-Time Adaptive Processing (STAP, Space-Time Adaptive Detection (STAD employs the data in the cell under test and those in the training to form reasonable detection statistics and consequently decides whether the target exists or not. The STAD has concise processing procedure and flexible design. Furthermore, the detection statistics usually possess the Constant False Alarm Rate (CFAR property, and hence it needs no additional CFAR processing. More importantly, the STAD usually exhibits improved detection performance than that of the conventional processing, which first suppresses the clutter then adopts other detection strategy. In this paper, we first summarize the key strongpoint of the STAD, then make a classification for the STAD, and finally give some future research tracks.

  3. Bonded hydrogen and hydrogen bonding in reciprocal space. Simulation of diffraction by a water molecule and dimer

    NARCIS (Netherlands)

    Poorthuis, G.H.A.; Feil, D.; Feil, D.

    1994-01-01

    There seems to be increasing interest in the electron density distribution in molecules and crystals. In particular, the effect of polarization due to internal fields in condensed matter is studied. X-ray diffraction data can contribute to the knowledge required. As the effects of polarization on

  4. One Novel Multiple-Target Plasmid Reference Molecule Targeting Eight Genetically Modified Canola Events for Genetically Modified Canola Detection.

    Science.gov (United States)

    Li, Zhuqing; Li, Xiang; Wang, Canhua; Song, Guiwen; Pi, Liqun; Zheng, Lan; Zhang, Dabing; Yang, Litao

    2017-09-27

    Multiple-target plasmid DNA reference materials have been generated and utilized as good substitutes of matrix-based reference materials in the analysis of genetically modified organisms (GMOs). Herein, we report the construction of one multiple-target plasmid reference molecule, pCAN, which harbors eight GM canola event-specific sequences (RF1, RF2, MS1, MS8, Topas 19/2, Oxy235, RT73, and T45) and a partial sequence of the canola endogenous reference gene PEP. The applicability of this plasmid reference material in qualitative and quantitative PCR assays of the eight GM canola events was evaluated, including the analysis of specificity, limit of detection (LOD), limit of quantification (LOQ), and performance of pCAN in the analysis of various canola samples, etc. The LODs are 15 copies for RF2, MS1, and RT73 assays using pCAN as the calibrator and 10 genome copies for the other events. The LOQ in each event-specific real-time PCR assay is 20 copies. In quantitative real-time PCR analysis, the PCR efficiencies of all event-specific and PEP assays are between 91% and 97%, and the squared regression coefficients (R 2 ) are all higher than 0.99. The quantification bias values varied from 0.47% to 20.68% with relative standard deviation (RSD) from 1.06% to 24.61% in the quantification of simulated samples. Furthermore, 10 practical canola samples sampled from imported shipments in the port of Shanghai, China, were analyzed employing pCAN as the calibrator, and the results were comparable with those assays using commercial certified materials as the calibrator. Concluding from these results, we believe that this newly developed pCAN plasmid is one good candidate for being a plasmid DNA reference material in the detection and quantification of the eight GM canola events in routine analysis.

  5. A versatile method to design stem-loop primer-based quantitative PCR assays for detecting small regulatory RNA molecules.

    Directory of Open Access Journals (Sweden)

    Zsolt Czimmerer

    Full Text Available Short regulatory RNA-s have been identified as key regulators of gene expression in eukaryotes. They have been involved in the regulation of both physiological and pathological processes such as embryonal development, immunoregulation and cancer. One of their relevant characteristics is their high stability, which makes them excellent candidates for use as biomarkers. Their number is constantly increasing as next generation sequencing methods reveal more and more details of their synthesis. These novel findings aim for new detection methods for the individual short regulatory RNA-s in order to be able to confirm the primary data and characterize newly identified subtypes in different biological conditions. We have developed a flexible method to design RT-qPCR assays that are very sensitive and robust. The newly designed assays were tested extensively in samples from plant, mouse and even human formalin fixed paraffin embedded tissues. Moreover, we have shown that these assays are able to quantify endogenously generated shRNA molecules. The assay design method is freely available for anyone who wishes to use a robust and flexible system for the quantitative analysis of matured regulatory RNA-s.

  6. A dual-mode single-molecule fluorescence assay for the detection of expanded CGG repeats in Fragile X syndrome.

    Science.gov (United States)

    Cannon, Brian; Pan, Cynthia; Chen, Liangjing; Hadd, Andrew G; Russell, Rick

    2013-01-01

    Fragile X syndrome is the leading cause of inherited mental impairment and is associated with expansions of CGG repeats within the FMR1 gene. To detect expanded CGG repeats, we developed a dual-mode single-molecule fluorescence assay that allows acquisition of two parallel, independent measures of repeat number based on (1) the number of Cy3-labeled probes bound to the repeat region and (2) the physical length of the electric field-linearized repeat region, obtained from the relative position of a single Cy5 dye near the end of the repeat region. Using target strands derived from cell-line DNA with defined numbers of CGG repeats, we show that this assay can rapidly and simultaneously measure the repeats of a collection of individual sample strands within a single field of view. With a low occurrence of false positives, the assay differentiated normal CGG repeat lengths (CGG( N ), N = 23) and expanded CGG repeat lengths (CGG( N ), N = 118), representing a premutation disease state. Further, mixtures of these DNAs gave results that correlated with their relative populations. This strategy may be useful for identifying heterozygosity or for screening collections of individuals, and it is readily adaptable for screening other repeat disorders.

  7. Mass Spectrometry in Cosmetic Science: Advanced Ionization Techniques for Detecting Trace Molecules in or on Human Skin

    Science.gov (United States)

    Motoyama, Akira; Kihara, Keishi

    2017-01-01

    To provide safe and effective products to customers in the cosmetic industry, mass spectrometry (MS) is an indispensable analytical tool. In addition to its outstanding sensitivity and specificity, the method is applicable to a wide variety of compounds, which makes it irreplaceable for the development of cosmetics, which requires the analysis of complex systems. Because most cosmetic products are applied directly to the skin and function as they are designed, monitoring the molecular compositions of endogenous or exogenous compounds in or on the skin is crucial to ensure the safety and efficacy of a cosmetic product. Recent advancements in MS and ionization techniques, such as MS imaging and ambient ionization, now provide access to richer and deeper molecular information with less time and effort. This brief review discusses advanced ionization techniques that are currently used in the field of cosmetic science using two examples, namely, the use of desorption electrospray ionization and zero-volt paperspray ionization to detect trace molecules in or on human skin. PMID:28959516

  8. Label-free solution-based kinetic study of aptamer-small molecule interactions by kinetic capillary electrophoresis with UV detection revealing how kinetics control equilibrium.

    Science.gov (United States)

    Bao, Jiayin; Krylova, Svetlana M; Reinstein, Oren; Johnson, Philip E; Krylov, Sergey N

    2011-11-15

    Here we demonstrate a label-free solution-based approach for studying the kinetics of biopolymer-small molecule interactions. The approach utilizes kinetic capillary electrophoresis (KCE) separation and UV light absorption detection of the unlabeled small molecule. In this proof-of-concept work, we applied KCE-UV to study kinetics of interaction between a small molecule and a DNA aptamer. From the kinetic analysis of a series of aptamers, we found that dissociation rather than binding controls the stability of the complex. Because of its label-free features and generic nature, KCE-UV promises to become a practical tool for challenging kinetic studies of biopolymer-small molecule interactions.

  9. Interest Point Detection for Multispectral Remote Sensing Image Using Phase Congruency in Illumination Space

    Directory of Open Access Journals (Sweden)

    CHEN Min

    2016-02-01

    Full Text Available A robust interest point detection algorithm based on illumination space and phase congruency is proposed in this paper. Firstly, image illumination space is constructed by using a parameters adaptive method. Secondly, a phase congruency based interest point detection algorithm is adopted to compute candidate points in illumination space. Then, all interest point candidates are mapped back to the original image and a non-maximum suppression step is added to find final interest points. Finally, the feature scale values of all interest points are calculated based on the Laplacian function. The proposed algorithm combines the advantages of illumination space and phase congruency, which makes the proposed method robust to the radiation variation of multispectral images. The experimental results show that the proposed method performs better than other traditional methods in feature repeatability rate and repeated features number.

  10. Research on the new type of multi-functional satellite system for space debris detection

    Science.gov (United States)

    Guo, Linghua; Fu, Qiang; Jiang, Huilin; Xu, Xihe

    2017-05-01

    With the rapid development of space exploration and utilization, orbital debris increases dramatically, leading to great threat to human space activities and spacecraft security. In this paper, a new type of multi-functional space debris satellite system (MSDS) was put forward, which shared main optical system, and possessed functions of multidimensional information detection, polarized remote sensing and high rate transmission. The MSDS system can meet the requirements of detection and identification for the small orbital debris which is 1000km faraway, as well as the requirements of the data transmission by 50 Mbps to 2.5 Gbps@200-1000 km. At the same time, by the method of satellite orbital maneuver and attitude adjusting, the orbital debris information that is real-time, complex and refined, allweather can be acquired and transmitted by the new system. Such new type of multifunctional satellite system can provide important and effective technology for international orbital debris detection.

  11. Nanomechanical microcantilever operated in vibration modes with use of RNA aptamer as receptor molecules for label-free detection of HCV helicase.

    Science.gov (United States)

    Hwang, Kyo Seon; Lee, Sang-Myung; Eom, Kilho; Lee, Jeong Hoon; Lee, Yoon-Sik; Park, Jung Ho; Yoon, Dae Sung; Kim, Tae Song

    2007-11-30

    We report the nanomechanical microcantilevers operated in vibration modes (oscillation) with use of RNA aptamers as receptor molecules for label-free detection of hepatitis C virus (HCV) helicase. The nanomechanical detection principle is that the ligand-receptor binding on the microcantilever surface induces the dynamic response change of microcantilevers. We implemented the label-free detection of HCV helicase in the low concentration as much as 100 pg/ml from measuring the dynamic response change of microcantilevers. Moreover, from the recent studies showing that the ligand-receptor binding generates the surface stress on the microcantilever, we estimate the surface stress, on the oscillating microcantilevers, induced by ligand-receptor binding, i.e. binding between HCV helicase and RNA aptamer. In this article, it is suggested that the oscillating microcantilevers with use of RNA aptamers as receptor molecules may enable one to implement the sensitive label-free detection of very small amount of small-scale proteins.

  12. MHC-like molecules in some nonmammalian vertebrates can be detected by some cross-reactive xenoantisera

    DEFF Research Database (Denmark)

    Kaufman, J; Skjoedt, K; Salomonsen, J

    1990-01-01

    Rabbit antisera raised to human and chicken MHC molecules were used to immunoprecipitate cross-reactive molecules from biosynthetically and cell surface-labeled spleen and/or blood cells of representative vertebrate species. Five major points emerged: 1) There were many nonspecific cross-reaction......Rabbit antisera raised to human and chicken MHC molecules were used to immunoprecipitate cross-reactive molecules from biosynthetically and cell surface-labeled spleen and/or blood cells of representative vertebrate species. Five major points emerged: 1) There were many nonspecific cross...

  13. Detection of constitutive molecules on Histoplasma capsulatum yeasts through single chain variable antibody fragments displayed in M13 phages.

    Science.gov (United States)

    Romero-Martínez, Rafael; Curiel-Quesada, Everardo; Becerril-Luján, Baltazar; Flores-Carreón, Arturo; Pérez-Torres, Armando; Taylor, Maria Lucia

    2007-06-01

    A nonimmune library, containing single chain variable fragments (scFv) of immunoglobulin human genes displayed on the surface of M13 filamentous phages, was used to recognize molecules exposed on Histoplasma capsulatum yeasts' surface, during their growth in synthetic medium. The scFv clones were checked in their consistency by Dot-ELISA using HRP/anti-M13 conjugate, and they were tested to recognize molecules on H. Capsulatum yeasts' surface by ELISA in plates. Three out of 80 scFv cones (C2, C6, and C52) reacted consistently with H. capsulatum molecules, and they recognized molecules from both H. capsulatum morphologic phases. However, C6 and C52 clones reacted better with molecules on the surface of whole yeasts, with molecules from the yeasts' cell-wall extract, and with molecules released to the supernatant of the yeast culture. Mycelial supernatants from other fungi, as well as from a Mycobacterium filtrate, were not recognized by scFv phage monoclones. Monoclones C2, C6, and C52 recognized yeast molecules irrespective of the H. capsulatum strains used; the C6 clone revealed a specific immunohistochemistry reaction when tested against homologous and heterologous fungal infected tissues. The scFv clones isolated will be a useful toll to define the role of their target molecules in the host-parasite relationship of histoplasmosis.

  14. Detection of RET (rearranged during transfection) variants and their downstream signal molecules in RET rearranged lung adenocarcinoma patients.

    Science.gov (United States)

    Kim, Jeong-Oh; Shin, Jung-Young; Kim, Min Young; Son, Kyoung Hwa; Jung, Chan Kwon; Kim, Tae-Jung; Kim, Su Young; Park, Jae Kil; Sung, Sook Whan; Bae, Sang Ju; Min, Hyun Jung; Kang, Jin-Hyoung

    2018-03-01

    We screened resected tumor tissues from patients with lung cancer for EGFR mutations, ALK rearrangements, and rearranged during transfection (RET) gene variants (including RET rearrangements and the Kinesin Family Member 5B (KIF5B)-RET fusion gene) using various methods including reverse transcription polymerase chain reaction (RT-PCR), transcript assays, fluorescence in situ hybridization (FISH), and immunohistochemistry (IHC). We also examined the protein expression of associated downstream signaling molecules to assess the effect of these variants on patient outcome. We constructed a tissue microarray (TMA) comprising 581 resected tumor tissues from patients with lung adenocarcinoma and analyzed the microarray by both FISH (using RET break-apart and KIF5B-RET SY translocation probes) and a commercial RET transcript assay. We evaluated the expression of RET and RET-related signaling molecules, including p-AKT and p-ERK, by TMA -based IHC staining. Among the 581 specimens, 51 (8.8%) specimens harbored RET rearrangements, including 12 cases (2.1%) carrying a KIF5B-RET fusion gene. Surprisingly, RET expression was lower in KIF5B-RET fusion gene-positive than in RET wild-type specimens. We detected activating EGFR mutations in 11 (21.6%) of the 51 RET variant-positive specimens. Among the KIF5B-RET fusion gene-positive specimens, p-ERK expression was significantly lower in the EGFR mutation subgroup showing RET expression than in the EGFR mutation subgroup that did not express RET. Similarly, the RET rearrangement group showed significant variation in the expression level of p-AKT (P = 0.028) and p-ERK, whose expression remarkably increased in specimens not expressing RET. The expression of p-ERK markedly increased in the RET rearrangement group regardless of RET expression. This result suggests that a combination of RET and ERK inhibitors may be an effective treatment strategy for lung adenocarcinoma patients harboring RET variants. Copyright © 2018 Elsevier

  15. CMsearch: simultaneous exploration of protein sequence space and structure space improves not only protein homology detection but also protein structure prediction

    KAUST Repository

    Cui, Xuefeng

    2016-06-15

    Motivation: Protein homology detection, a fundamental problem in computational biology, is an indispensable step toward predicting protein structures and understanding protein functions. Despite the advances in recent decades on sequence alignment, threading and alignment-free methods, protein homology detection remains a challenging open problem. Recently, network methods that try to find transitive paths in the protein structure space demonstrate the importance of incorporating network information of the structure space. Yet, current methods merge the sequence space and the structure space into a single space, and thus introduce inconsistency in combining different sources of information. Method: We present a novel network-based protein homology detection method, CMsearch, based on cross-modal learning. Instead of exploring a single network built from the mixture of sequence and structure space information, CMsearch builds two separate networks to represent the sequence space and the structure space. It then learns sequence–structure correlation by simultaneously taking sequence information, structure information, sequence space information and structure space information into consideration. Results: We tested CMsearch on two challenging tasks, protein homology detection and protein structure prediction, by querying all 8332 PDB40 proteins. Our results demonstrate that CMsearch is insensitive to the similarity metrics used to define the sequence and the structure spaces. By using HMM–HMM alignment as the sequence similarity metric, CMsearch clearly outperforms state-of-the-art homology detection methods and the CASP-winning template-based protein structure prediction methods.

  16. Change detection for hyperspectral sensing in a transformed low-dimensional space

    Energy Technology Data Exchange (ETDEWEB)

    Foy, Bernard R [Los Alamos National Laboratory; Theiler, James [Los Alamos National Laboratory

    2010-01-01

    We present an approach to the problem of change in hyperspectral imagery that operates in a two-dimensional space. The coordinates in the space are related to Mahalanobis distances for the combined ('stacked') data and the individual hyperspectral scenes. Although it is only two-dimensional, this space is rich enough to include several well-known change detection algorithms, including the hyperbolic anomalous change detector, based on Gaussian scene clutter, and the EC-uncorrelated detector based on heavy-tailed (elliptically contoured) clutter. Because this space is only two-dimensional, adaptive machine learning methods can produce new change detectors without being stymied by the curse of dimensionality. We investigate, in particular, the utility of the support vector machine for learning boundaries in this 2-D space, and compare the performance of the resulting nonlinearly adaptjve detector to change detectors that have themselves shown good performance.

  17. Design of Hybrid Network Anomalies Detection System (H-NADS Using IP Gray Space Analysis

    Directory of Open Access Journals (Sweden)

    Yogendra Kumar JAIN

    2009-01-01

    Full Text Available In Network Security, there is a major issue to secure the public or private network from abnormal users. It is because each network is made up of users, services and computers with a specific behavior that is also called as heterogeneous system. To detect abnormal users, anomaly detection system (ADS is used. In this paper, we present a novel and hybrid Anomaly Detection System with the uses of IP gray space analysis and dominant scanning port identification heuristics used to detect various anomalous users with their potential behaviors. This methodology is the combination of both statistical and rule based anomaly detection which detects five types of anomalies with their three types of potential behaviors and generates respective alarm messages to GUI.

  18. Leak detection of the Space Station Freedom U.S. Lab vacuum system using reverse flow leak detection methodology

    Science.gov (United States)

    Moore, Jeffrey D.; Shepherd, James E.; Masden, Darrell E.

    1991-01-01

    A vacuum system leak detection technique (reverse flow leak detection) under development for use aboard Space Station Freedom is presented. The technique will be applied to the Vacuum System (VS) and Waste Gas Management Subsystem (WGMS) of the U.S. Lab Module. These two systems contain over 45.7 m of distributed vacuum tubing located in remote utility runs. Fluid flow calculations which utilize known system geometry and measured steady state pressure measurements from the VS and WGMS can be used to identify leak sites within +/- 38 cm. Exact leak position can then be pinpointed by conventional tracer gas leak detection in the identified region. Tests have been performed using a simple, unrestricted 12.8 m length of vacuum tubing with a calibrated air leak attached.

  19. Subunits of highly Fluorescent Protein R-Phycoerythrin as Probes for Cell Imaging and Single-Molecule Detection

    Energy Technology Data Exchange (ETDEWEB)

    Isailovic, Dragan [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    The purposes of our research were: (1) To characterize subunits of highly fluorescent protein R-Phycoerythrin (R-PE) and check their suitability for single-molecule detection (SMD) and cell imaging, (2) To extend the use of R-PE subunits through design of similar proteins that will be used as probes for microscopy and spectral imaging in a single cell, and (3) To demonstrate a high-throughput spectral imaging method that will rival spectral flow cytometry in the analysis of individual cells. We first demonstrated that R-PE subunits have spectroscopic and structural characteristics that make them suitable for SMD. Subunits were isolated from R-PE by high-performance liquid chromatography (HPLC) and detected as single molecules by total internal reflection fluorescence microscopy (TIRFM). In addition, R-PE subunits and their enzymatic digests were characterized by several separation and detection methods including HPLC, capillary electrophoresis, sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE) and HPLC-electrospray ionization mass spectrometry (ESI-MS). Favorable absorption and fluorescence of the R-PE subunits and digest peptides originate from phycoerythrobilin (PEB) and phycourobilin (PUB) chromophores that are covalently attached to cysteine residues. High absorption coefficients and strong fluorescence (even under denaturing conditions), broad excitation and emission fluorescence spectra in the visible region of electromagnetic spectrum, and relatively low molecular weights make these molecules suitable for use as fluorescence labels of biomolecules and cells. We further designed fluorescent proteins both in vitro and in vivo (in Escherichia coli) based on the highly specific attachment of PEB chromophore to genetically expressed apo-subunits of R-PE. In one example, apo-alpha and apo-beta R-PE subunits were cloned from red algae Polisiphonia boldii (P. boldii), and expressed in E. coli. Although expressed apo-subunits formed inclusion

  20. Inner-shell photoelectron angular distributions from fixed-in-space OCS molecules: comparison between experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, A V [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan); Institute of Physics, St Petersburg State University, 198504 St Petersburg (Russian Federation); Adachi, J [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan); Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Motoki, S [Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, (Japan); Takahashi, M [Institute for Molecular Science, Okazaki 444-8585 (Japan); Yagishita, A [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan); Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2005-10-28

    Photoelectron angular distributions (PADs) for O 1s, C 1s and S 2p{sub 1/2}, 2p{sub 3/2} ionization of OCS molecules have been measured in shape resonance regions. These PAD results are compared with the results for O 1s and C 1s ionization of CO molecules, and multi-scattering X{alpha} (MSX{alpha}) calculations. The mechanism of the PAD formation both for parallel and perpendicular transitions differs very significantly in these molecules and a step from a two-centre potential (CO) to a three-centre potential (OCS) plays a principal role in electron scattering and the formation of the resulting PAD. For parallel transitions, it is found that for the S 2p and O 1s ionization the photoelectrons are emitted preferentially in a hemisphere directed to the ionized S and O atom, respectively. In OCS O 1s ionization, the S-C fragment plays the role of a strong 'scatterer' for photoelectrons, and in the shape resonance region most intensities of the PADs are concentrated on the region directed to the O atom. The MSX{alpha} calculations for perpendicular transitions reproduce the experimental data, but not so well as in the case of parallel transitions. The results of PAD, calculated with different l{sub max} on different atomic centres, reveal the important role of the d (l = 2) partial wave for the S atom in the partial wave decompositions of photoelectron wavefunctions.

  1. High sensitivity surface plasmon resonance biosensor for detection of microRNA and small molecule based on graphene oxide-gold nanoparticles composites.

    Science.gov (United States)

    Li, Qing; Wang, Qing; Yang, Xiaohai; Wang, Kemin; Zhang, Hua; Nie, Wenyan

    2017-11-01

    A versatile and sensitive surface plasmon resonance (SPR) biosensor based on two layers of graphene oxide-gold nanoparticles (GO-AuNPs) composites was designed for the detection of microRNA (miRNA) and small molecule adenosine. The bottom layer, which acted as a functionalized substrate on the sensor chip, provided a high specific surface area convenient for the immobilization of capture DNA molecules. The upper layer served as a signal-amplification element. By employing these two layers of GO-AuNPs composites, the dual amplification strategy was achieved so that a measurement of miRNA-141 with a detection limit of 0.1fM was obtained. Moreover, the developed SPR biosensor showed decent selectivity toward miRNA-200 family members. Especially, the SPR biosensor demonstrated its applicability for the detection of miRNA-141 in cancer cell extractions, and the results obtained were consistent with those obtained by qRT-PCR. Interestingly, small molecule adenosine could also be detected using this SPR biosensor in combination with a split aptamer. Considering the superior sensitivity, selectivity and generality, this work promised much potential for the detection of various biomolecules. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. NEOSSat: a Canadian small space telescope for near Earth asteroid detection

    Science.gov (United States)

    Laurin, Denis; Hildebrand, Alan; Cardinal, Rob; Harvey, William; Tafazoli, Siamak

    2008-07-01

    Although there is some success in finding Near Earth asteroids from ground-based telescopes, there is a marked advantage in performing the search from space. The ability to search at closer elongations from the sun and being able to observe continuously, allowing quick revisits of new asteroids, are some of the unique benefits of a space platform. The Canadian Space Agency (CSA) together with Defense Research and Development Canada (DRDC) are planning a micro-satellite platform with a 15 cm telescope dedicated for near space surveillance. The NEOSSat (Near Earth Object Surveillance) spacecraft is expected to be able to detect 20 v magnitude objects with a 100 sec exposure, with a 0.85 deg FOV, on a 1024x1024 CCD, and sub arcsec pointing stability. For detection of NEO small bodies, it will be able to search an area from 45 degrees solar elongation and approximately 40 degrees north to south degrees in elevation. The observation strategy will be optimized to find as many asteroids as possible, based on recent models of asteroid population. Ground based telescopes will also be used to complement follow-ups for orbit determination when possible. The microsatellite is based on the CSA very successful MOST micro-satellite, operating since 2003. Baselined for launch in 2010, the NEOSSat is a shared project with DRDC to demonstrate the technology of an inexpensive space platform to detect High Earth Orbit (HEOSS) earth-orbiting satellites and debris.

  3. Edge detection and image segmentation of space scenes using fractal analyses

    Science.gov (United States)

    Cleghorn, Timothy F.; Fuller, J. J.

    1992-01-01

    A method was developed for segmenting images of space scenes into manmade and natural components, using fractal dimensions and lacunarities. Calculations of these parameters are presented. Results are presented for a variety of aerospace images, showing that it is possible to perform edge detections of manmade objects against natural background such as those seen in an aerospace environment.

  4. 3D shape detection of the indoor space based on 3D-Hough method

    OpenAIRE

    安齋, 達也; ANZAI, Tatsuya

    2013-01-01

    This paper describes methods for detecting the 3D shapes of the indoor space that is represented as a combination of planes such as a wall, desk, or whatnot. Detecting the planes makes it possible to perform calibration of multiple sensors and 3D mapping, and then produces various services such as the acquisition of life logs, AR interaction, and invader detection. This paper proposes and verifies three algorithms. First, it mentions a way to use2D-Hough.The proposed technique converts 3D dat...

  5. MHC-like molecules in some nonmammalian vertebrates can be detected by some cross-reactive xenoantisera

    DEFF Research Database (Denmark)

    Kaufman, J; Skjoedt, K; Salomonsen, J

    1990-01-01

    Rabbit antisera raised to human and chicken MHC molecules were used to immunoprecipitate cross-reactive molecules from biosynthetically and cell surface-labeled spleen and/or blood cells of representative vertebrate species. Five major points emerged: 1) There were many nonspecific cross......-reactions using these techniques, so various criteria were developed to distinguish these from true MHC-like molecules. 2) Only very small subpopulations of immunogen-specific antibodies cross-reacted with MHC-like molecules in other nonmammalian species. These subpopulations were different for each species...... and even within a species, sometimes being so limited as to behave like alloantisera. This led to a very scattered pattern of true cross-reactions that sometimes failed to reflect the properties of the bulk antibody population. 3) Antisera containing antibodies to class II beta- and class I alpha...

  6. Detection of the aromatic molecule benzonitrile (c-C6H5CN) in the interstellar medium.

    Science.gov (United States)

    McGuire, Brett A; Burkhardt, Andrew M; Kalenskii, Sergei; Shingledecker, Christopher N; Remijan, Anthony J; Herbst, Eric; McCarthy, Michael C

    2018-01-12

    Polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are thought to be widespread throughout the universe, because these classes of molecules are probably responsible for the unidentified infrared bands, a set of emission features seen in numerous Galactic and extragalactic sources. Despite their expected ubiquity, astronomical identification of specific aromatic molecules has proven elusive. We present the discovery of benzonitrile ( c -C 6 H 5 CN), one of the simplest nitrogen-bearing aromatic molecules, in the interstellar medium. We observed hyperfine-resolved transitions of benzonitrile in emission from the molecular cloud TMC-1. Simple aromatic molecules such as benzonitrile may be precursors for polycyclic aromatic hydrocarbon formation, providing a chemical link to the carriers of the unidentified infrared bands. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  7. Detection of the aromatic molecule benzonitrile (c-C6H5CN) in the interstellar medium

    Science.gov (United States)

    McGuire, Brett A.; Burkhardt, Andrew M.; Kalenskii, Sergei; Shingledecker, Christopher N.; Remijan, Anthony J.; Herbst, Eric; McCarthy, Michael C.

    2018-01-01

    Polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are thought to be widespread throughout the universe, because these classes of molecules are probably responsible for the unidentified infrared bands, a set of emission features seen in numerous Galactic and extragalactic sources. Despite their expected ubiquity, astronomical identification of specific aromatic molecules has proven elusive. We present the discovery of benzonitrile (c-C6H5CN), one of the simplest nitrogen-bearing aromatic molecules, in the interstellar medium. We observed hyperfine-resolved transitions of benzonitrile in emission from the molecular cloud TMC-1. Simple aromatic molecules such as benzonitrile may be precursors for polycyclic aromatic hydrocarbon formation, providing a chemical link to the carriers of the unidentified infrared bands.

  8. A Novel Line Space Voting Method for Vanishing-Point Detection of General Road Images

    Directory of Open Access Journals (Sweden)

    Zongsheng Wu

    2016-06-01

    Full Text Available Vanishing-point detection is an important component for the visual navigation system of an autonomous mobile robot. In this paper, we present a novel line space voting method for fast vanishing-point detection. First, the line segments are detected from the road image by the line segment detector (LSD method according to the pixel’s gradient and texture orientation computed by the Sobel operator. Then, the vanishing-point of the road is voted on by considering the points of the lines and their neighborhood spaces with weighting methods. Our algorithm is simple, fast, and easy to implement with high accuracy. It has been experimentally tested with over hundreds of structured and unstructured road images. The experimental results indicate that the proposed method is effective and can meet the real-time requirements of navigation for autonomous mobile robots and unmanned ground vehicles.

  9. A Novel Line Space Voting Method for Vanishing-Point Detection of General Road Images.

    Science.gov (United States)

    Wu, Zongsheng; Fu, Weiping; Xue, Ru; Wang, Wen

    2016-06-23

    Vanishing-point detection is an important component for the visual navigation system of an autonomous mobile robot. In this paper, we present a novel line space voting method for fast vanishing-point detection. First, the line segments are detected from the road image by the line segment detector (LSD) method according to the pixel's gradient and texture orientation computed by the Sobel operator. Then, the vanishing-point of the road is voted on by considering the points of the lines and their neighborhood spaces with weighting methods. Our algorithm is simple, fast, and easy to implement with high accuracy. It has been experimentally tested with over hundreds of structured and unstructured road images. The experimental results indicate that the proposed method is effective and can meet the real-time requirements of navigation for autonomous mobile robots and unmanned ground vehicles.

  10. Detection of IgE Reactivity to a Handful of Allergen Molecules in Early Childhood Predicts Respiratory Allergy in Adolescence.

    Science.gov (United States)

    Wickman, Magnus; Lupinek, Christian; Andersson, Niklas; Belgrave, Danielle; Asarnoj, Anna; Benet, Marta; Pinart, Mariona; Wieser, Sandra; Garcia-Aymerich, Judith; Baar, Alexandra; Pershagen, Göran; Simpson, Angela; Kull, Inger; Bergström, Anna; Melén, Erik; Hamsten, Carl; Antó, Josep M; Bousquet, Jean; Custovic, Adnan; Valenta, Rudolf; van Hage, Marianne

    2017-12-01

    Sensitization in early childhood may precede respiratory allergy in adolescence. IgE reactivity against 132 allergen molecules was evaluated using the MeDALL microarray in sera obtained from a random sample of 786 children at the age of 4, 8 and 16years in a population based birth cohort (BAMSE). Symptoms were analyzed by questionnaire at ages 4, 8 and 16years. Clinically and independent relevant allergen molecules accounting for ≥90% of IgE reactivities in sensitized individuals and at all time-points were identified as risk molecules and used to predict respiratory allergy. The data was replicated in the Manchester Asthma and Allergy Study (MAAS) birth cohort by studying IgE reactivity with the use of a commercial IgE microarray. Sera were obtained from children at the ages of 3, 5, 8 and 11years (N=248) and the outcome was studied at 11years. In the BAMSE cohort 4 risk molecules could be identified, i.e.: Ara h 1 (peanut), Bet v 1 (birch), Fel d 1 (cat), Phl p 1 (grass). For MAAS the corresponding number of molecules was 5: Der p 1 (dust mite), Der f 2 (dust mite), Phl p 1 (grass), Phl p 5 (grass), Fel d 1 (cat). In BAMSE, early IgE reactivity to ≥3 of 4 allergen molecules at four years predicted incident and persistent asthma and/or rhinitis at 16years (87% and 95%, respectively). The corresponding proportions in the MAAS cohort at 16years were 100% and 100%, respectively, for IgE reactivity to ≥3 of 5 risk molecules. IgE reactivity to a few allergen molecules early in life identifies children with a high risk of asthma and/or rhinitis at 16years. These findings will be of importance for developing preventive strategies for asthma and rhinitis in children. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  11. Space Debris Detection in Low Earth Orbit with the Sardinia Radio Telescope

    Directory of Open Access Journals (Sweden)

    Giacomo Muntoni

    2017-08-01

    Full Text Available Space debris are orbiting objects that represent a major threat for space operations. The most used countermeasure to face this threat is, by far, collision avoidance, namely the set of maneuvers that allow to avoid a collision with the space debris. Since collision avoidance is tightly related to the knowledge of the debris state (position and speed, the observation of the orbital debris is the key of the problem. In this work a bistatic radar configuration named BIRALET (BIstatic RAdar for LEO Tracking is used to detect a set of space debris at 410 MHz, using the Sardinia Radio Telescope as the receiver antenna. The signal-to-noise ratio, the Doppler shift and the frequency spectrum for each debris are reported.

  12. Detection and segmentation of intersection and branch structures in medical images using orientation space

    International Nuclear Information System (INIS)

    Chen, Jian; Sato, Yoshinobu; Tamura, Shinichi

    1999-01-01

    The purpose of this paper is to present appropriate line segmentation for intersections (X-junctions) and branches (T-junctions). In the local regions of intersections and branches, multiple orientations occur. We propose a novel representation called the ''orientation space'', which is derived by adding the orientation axis to the abscissa and the ordinate of the image. The orientation space representation is constructed by treating the orientation parameter, to which Gabor filters can be tuned, as a continuous variable. The problem of multiple orientation line segmentation is dealt with by thresholding 3D images of the orientation space and then detecting the connected components therein. In this way, X-junctions and T-junctions can be separated effectively. Experimental results obtained using synthesized and real biomedical images are presented. In particular, overlapping vessels in an X-ray coronary angiogram were well segmented by orientation space filtering. (author)

  13. Optimization of thermochemolysis analysis conditions for the in situ detection of organic compounds in Martian soil with the Mars Organic Molecule Analyzer (MOMA) experiment

    Science.gov (United States)

    Morisson, Marietta; Buch, Arnaud; Szopa, Cyril; Raulin, François; Stambouli, Moncef

    2017-04-01

    Martian surface is exposed to harsh radiative and oxidative conditions which are destructive for organic molecules. That is why the future ExoMars rover will examine the molecular composition of samples acquired from depths down to two meters below the Martian surface, where organics may have been protected from radiative and oxidative degradation. The samples will then be analyzed by the Pyrolysis-Gas Chromatography-Mass Spectrometry (Pyr-GC-MS) operational mode of the Mars Organic Molecule Analyzer (MOMA) instrument. To prevent thermal alteration of organic molecules during pyrolysis, thermochemolysis with tetramethylammonium hydroxide (TMAH) will extract the organics from the mineral matrix and methylate the polar functional groups, allowing the volatilization of molecules at lower temperatures and protecting the most labile chemical groups from thermal degradation. This study has been carried out on a Martian regolith analogue (JSC-Mars-1) with a high organic content with the aim of optimizing the thermochemolysis temperature within operating conditions similar to the MOMA experiment ones. We also performed Pyrolysis-GC-MS analysis as a comparison. The results show that, unlike pyrolysis alone - which mainly produces aromatics, namely thermally altered molecules - thermochemolysis allows the extraction and identification of numerous organic molecules of astrobiological interest. They also show that the main compounds start to be detectable at low thermochemolysis temperatures ranging from 400°C to 600°C. However, we noticed that the more the temperature increases, the more the chromatograms are saturated with thermally evolved molecules leading to many coelutions and making identification difficult.

  14. Methodological demonstration of laser beam pointing control for space gravitational wave detection missions.

    Science.gov (United States)

    Dong, Yu-Hui; Liu, He-Shan; Luo, Zi-Ren; Li, Yu-Qiong; Jin, Gang

    2014-07-01

    In space laser interferometer gravitational wave (G.W.) detection missions, the stability of the laser beam pointing direction has to be kept at 10 nrad/√Hz. Otherwise, the beam pointing jitter noise will dominate the noise budget and make the detection of G.W. impossible. Disturbed by the residue non-conservative forces, the fluctuation of the laser beam pointing direction could be a few μrad/√Hz at frequencies from 0.1 mHz to 10 Hz. Therefore, the laser beam pointing control system is an essential requirement for those space G.W. detection missions. An on-ground test of such beam pointing control system is performed, where the Differential Wave-front Sensing technique is used to sense the beams pointing jitter. An active controlled steering mirror is employed to adjust the beam pointing direction to compensate the jitter. The experimental result shows that the pointing control system can be used for very large dynamic range up to 5 μrad. At the interested frequencies of space G.W. detection missions, between 1 mHz and 1 Hz, beam pointing stability of 6 nrad/√Hz is achieved.

  15. Methodological demonstration of laser beam pointing control for space gravitational wave detection missions

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yu-Hui; Liu, He-Shan [National Microgravity Laboratory (NML), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100190 (China); Luo, Zi-Ren; Li, Yu-Qiong; Jin, Gang, E-mail: gajin@imech.ac.cn [National Microgravity Laboratory (NML), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-07-15

    In space laser interferometer gravitational wave (G.W.) detection missions, the stability of the laser beam pointing direction has to be kept at 10 nrad/√Hz. Otherwise, the beam pointing jitter noise will dominate the noise budget and make the detection of G.W. impossible. Disturbed by the residue non-conservative forces, the fluctuation of the laser beam pointing direction could be a few μrad/√Hz at frequencies from 0.1 mHz to 10 Hz. Therefore, the laser beam pointing control system is an essential requirement for those space G.W. detection missions. An on-ground test of such beam pointing control system is performed, where the Differential Wave-front Sensing technique is used to sense the beams pointing jitter. An active controlled steering mirror is employed to adjust the beam pointing direction to compensate the jitter. The experimental result shows that the pointing control system can be used for very large dynamic range up to 5 μrad. At the interested frequencies of space G.W. detection missions, between 1 mHz and 1 Hz, beam pointing stability of 6 nrad/√Hz is achieved.

  16. Highlight on the indigenous organic molecules detected on Mars by SAM and potential sources of artifacts and backgrounds generated by the sample preparation

    Science.gov (United States)

    Buch, A.; Belmahdi, I.; Szopa, C.; Freissinet, C.; Glavin, D. P.; Coll, P. J.; Cabane, M.; Millan, M.; Eigenbrode, J. L.; Navarro-Gonzalez, R.; Stern, J. C.; Pinnick, V. T.; Coscia, D.; Teinturier, S.; Stambouli, M.; Dequaire, T.; Mahaffy, P. R.

    2015-12-01

    and molecules that may constitute organic material precursors sources. References: [1] Mahaffy, P. et al. (2012) Space Sci Rev, 170, 401-478. [2] Glavin, D. et al. (2013), JGR. [3] Leshin L. et al. (2013), Science, [4] Williams, A.J., Eigenbrode, J.L.,m Floyd, M.M., Wilhelm, M.B., and Mahaffy, P.R., (2015), GSA. [5] Eigenbrode, J.L. et al. (2010), LPSC, abst.1460.

  17. TiO2/Gold nanocomposite as an extremely sensitive molecule sensor for NO2 detection: A DFT study

    Directory of Open Access Journals (Sweden)

    Amirali Abbasi

    2016-07-01

    Full Text Available First-principles calculations within density functional theory (DFT have been performed to investigate the interactions of NO2 molecules with TiO2/Gold nanocomposites in order to completely exploit the adsorption properties of these nanostructures. Given the need to further comprehend the behavior of the NO2 molecules positioned between the TiO2 nanoparticle and Au monolayer, we have geometrically optimized the complex systems consisting of the NO2 molecule oriented at appropriate positions between the nanoparticle and Au monolayer. The structural properties such as bond lengths, bond angles, adsorption energies and Mulliken population analysis and the electronic properties including the density of states and molecular orbitals have been also analyzed in detail. The results indicate that the interaction between NO2 and undoped TiO2-N/Gold nanocomposites is stronger than that between gas molecules and N-doped TiO2/Gold nanocomposites, which reveals that the pristine nanocomposite can react with NO2 molecule more efficiently. Therefore, the obtained results also suggest a theoretical basis for the potential applications of TiO2/Gold nanocomposites in gas sensing, which could help in the developing of novel TiO2 based advanced sensor devices.

  18. Redox Cycling Realized in Paper-Based Biochemical Sensor for Selective Detection of Reversible Redox Molecules Without Micro/Nano Fabrication Process.

    Science.gov (United States)

    Yamamoto, So; Uno, Shigeyasu

    2018-02-28

    This paper describes a paper-based biochemical sensor that realizes redox cycling with close interelectrode distance. Two electrodes, the generator and collector electrodes, can detect steady-state oxidation and reduction currents when suitable potential is held at each electrode. The sensor has two gold plates on both sides of a piece of chromatography paper and defines the interelectrode distance by the thickness of the paper (180 μm) without any micro-fabrication processes. Our proposed sensor geometry has successfully exhibited signatures of redox cycling. As a result, the concentration of ferrocyanide as reversible redox molecules was successfully quantified under the interference by ascorbic acid as a strong irreversible reducing agent. This was possible because the ascorbic acids are completely consumed by the irreversible reaction, while maintaining redox cycling of reversible ferrocyanide. This suggests that a sensor based on the redox cycling method will be suitable for detecting target molecules at low concentration.

  19. Detectability of CO2 Flux Signals by a Space-Based Lidar Mission

    Science.gov (United States)

    Hammerling, Dorit M.; Kawa, S. Randolph; Schaefer, Kevin; Doney, Scott; Michalak, Anna M.

    2015-01-01

    Satellite observations of carbon dioxide (CO2) offer novel and distinctive opportunities for improving our quantitative understanding of the carbon cycle. Prospective observations include those from space-based lidar such as the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. Here we explore the ability of such a mission to detect regional changes in CO2 fluxes. We investigate these using three prototypical case studies, namely the thawing of permafrost in the Northern High Latitudes, the shifting of fossil fuel emissions from Europe to China, and changes in the source-sink characteristics of the Southern Ocean. These three scenarios were used to design signal detection studies to investigate the ability to detect the unfolding of these scenarios compared to a baseline scenario. Results indicate that the ASCENDS mission could detect the types of signals investigated in this study, with the caveat that the study is based on some simplifying assumptions. The permafrost thawing flux perturbation is readily detectable at a high level of significance. The fossil fuel emission detectability is directly related to the strength of the signal and the level of measurement noise. For a nominal (lower) fossil fuel emission signal, only the idealized noise-free instrument test case produces a clearly detectable signal, while experiments with more realistic noise levels capture the signal only in the higher (exaggerated) signal case. For the Southern Ocean scenario, differences due to the natural variability in the ENSO climatic mode are primarily detectable as a zonal increase.

  20. Ultra-high-density 3D DNA arrays within nanoporous biocompatible membranes for single-molecule-level detection and purification of circulating nucleic acids

    Science.gov (United States)

    Aramesh, M.; Shimoni, O.; Fox, K.; Karle, T. J.; Lohrmann, A.; Ostrikov, K.; Prawer, S.; Cervenka, J.

    2015-03-01

    Extracellular nucleic acids freely circulating in blood and other physiologic fluids are important biomarkers for non-invasive diagnostics and early detection of cancer and other diseases, yet difficult to detect because they exist in very low concentrations and large volumes. Here we demonstrate a new broad-range sensor platform for ultrasensitive and selective detection of circulating DNA down to the single-molecule level. The biosensor is based on a chemically functionalized nanoporous diamond-like carbon (DLC) coated alumina membrane. The few nanometer-thick, yet perfect and continuous DLC-coating confers the chemical stability and biocompatibility of the sensor, allowing its direct application in biological conditions. The selective detection is based on complementary hybridization of a fluorescently-tagged circulating cancer oncomarker (a 21-mer nucleic acid) with covalently immobilized DNA on the surface of the membrane. The captured DNAs are detected in the nanoporous structure of the sensor using confocal scanning laser microscopy. The flow-through membrane sensor demonstrates broad-range sensitivity, spanning from 1015 molecules per cm2 down to single molecules, which is several orders of magnitude improvement compared to the flat DNA microarrays. Our study suggests that these flow-through type nanoporous sensors represent a new powerful platform for large volume sampling and ultrasensitive detection of different chemical biomarkers.Extracellular nucleic acids freely circulating in blood and other physiologic fluids are important biomarkers for non-invasive diagnostics and early detection of cancer and other diseases, yet difficult to detect because they exist in very low concentrations and large volumes. Here we demonstrate a new broad-range sensor platform for ultrasensitive and selective detection of circulating DNA down to the single-molecule level. The biosensor is based on a chemically functionalized nanoporous diamond-like carbon (DLC) coated

  1. Modeling Synthetic Spectra for Transiting Extrasolar Giant Planets: Detectability of H2S and PH3 with the James Webb Space Telescope

    Science.gov (United States)

    Wang, Dong; Miguel, Yamila; Lunine, Jonathan

    2017-12-01

    The James Webb Space Telescope (JWST)’s large aperture and wide wavelength coverage will enable it to collect the highest-quality transit spectra observed so far. For exoplanetary atmospheres we expect to retrieve the abundance of the most abundant molecules, such as H2O, CO, and CH4. Other molecules, such as H2S and PH3, have been observed in Jupiter and Saturn but their chemistry and detectability in strongly irradiated planets are largely unknown. In this paper, we make the first effort to study their spectral features in solar composition atmospheres, and evaluate their detectability with the JWST. We model the chemistry of phosphorus and sulfur in solar composition atmospheres. Our model includes the effect of vertical transport. Photochemistry effects are not included in our calculations. Using the abundance profiles, we model the JWST transmission and emission spectra for a K = 6.8 G-type star and for planets with cloud-free solar composition atmospheres. We find PH3 is detectable at 3σ from transmission spectra of the simulated atmosphere with {T}{eq} 1500 K using the NIRCam LW grism F322W2 mode with a total observing time of 24.0 hr. Our results specifically highlight the importance of including H2S for future abundance retrieval with the JWST. The presence of clouds and hazes challenges the detections of PH3 and H2S, but H2S features are still expected to be present in the emission spectra.

  2. Design of a low-temperature plasma (LTP) probe with adjustable output temperature and variable beam diameter for the direct detection of organic molecules.

    Science.gov (United States)

    Martínez-Jarquín, Sandra; Winkler, Robert

    2013-03-15

    The direct detection of organic molecules by mass spectrometry requires ionization methods which are compatible with ambient conditions. A relatively new strategy is the use of a free low-temperature plasma beam for ionization. The objective is to design a safe and adjustable plasma beam to enable optimal ionization and desorption parameters for specific molecules. A plasma probe based on a dielectric barrier discharge was designed, where the plasma is guided through an internal second tube. This setup permits different beam diameter settings and the control of the plasma temperature. The ionization and desorption of pure organic compounds, as well as their direct detection from roasted coffee beans, were tested. The presented plasma probe provides improved safety with respect to arcing, ozone generation and electric shock, compared with conventional designs. The functionality of previously reported devices is expanded. A defined plasma diameter can be set by choosing the appropriate insert, while the input voltage controls the plasma temperature. The variation of measurement parameters enables the optimized direct detection of target compounds from roasted coffee beans, such as caffeine, guaiacol and vanillin. The presented low-temperature plasma probe allows the fine-tuning of ionization and desorption parameters, according to the target molecules. Possible applications include: (1) The ambient ionization and desorption of organic compounds with different volatility and (2) The direct analysis of food products such as roasted coffee beans. Copyright © 2013 John Wiley & Sons, Ltd.

  3. The impact of the phase-space density on the indirect detection of dark matter

    International Nuclear Information System (INIS)

    Ferrer, Francesc; Hunter, Daniel R.

    2013-01-01

    We study the indirect detection of dark matter when the local dark matter velocity distribution depends upon position, as expected for the Milky Way and its dwarf spheroidal satellites, and the annihilation cross-section is not purely s-wave. Using a phase-space distribution consistent with the dark matter density profile, we present estimates of cosmic and gamma-ray fluxes from dark matter annihilations. The expectations for the indirect detection of dark matter can differ significantly from the usual calculation that assumes that the velocity of the dark matter particles follows a Maxwell-Boltzmann distribution

  4. Kepler Detected Gravity-Mode Period Spacings in a Red Giant Star

    DEFF Research Database (Denmark)

    Beck, P.G.; Bedding, Timothy R.; Mosser, Benoit

    2011-01-01

    Stellar interiors are inaccessible through direct observations. For this reason, helioseismologists made use of the Sun’s acoustic oscillation modes to tune models of its structure. The quest to detect modes that probe the solar core has been ongoing for decades. We report the detection of mixed ...... modes penetrating all the way to the core of an evolved star from 320 days of observations with the Kepler satellite. The period spacings of these mixed modes are directly dependent on the density gradient between the core region and the convective envelope....

  5. Evaluation of an Interferometric Sensor for In-Space Detection of Gas Leaks

    Science.gov (United States)

    Polzin, Kurt A.; Korman, Valentin; Sinko, John; Hendrickson, Adam

    2009-01-01

    Space mission planning often involves long-term storage of volatile liquids or high-pressure gases. These may include cryogenic fuels and oxidizers, high-pressure gases, and life-support-critical consumables. The risk associated with the storage of fluids and gases in space systems has long been an issue and the ability to retain these fluids is often tied to mission success. A leak in the storage or distribution system can cause many different problems, including a simple, but mission endangering, loss of inventory or, in severe cases, unbalanced thrust loads on a flight vehicle. Cryogenic propellants are especially difficult to store, especially over a long duration. The propellant can boil off and be lost through the insulating walls of the tank or simple thermal cycling of the fittings, valves, and propellant feed lines may unseat seals allowing the fluid to escape. Current NASA missions call for long-duration in-space storage of propellants, oxidizers, and life support supplies. Leaks of a scale detectable through a pressure drop in the storage tank are often catastrophic and have long been the focus of ground-based mitigation efforts where redundant systems are often employed. However, there is presently no technology available for detecting and monitoring low-level, but still mission-endangering, gas leaks in space. Standard in-space gas detection methods either have a very limited pressure range over which they operate effectively or are limited to certain gases. Mass spectrometer systems are able to perform the detection tasks, but their size, mass and use of high voltage, which could potentially lead to an arc that ignites a combustible propellent, severely limit their usefulness in a space system. In this paper, we present results from testing of the light-based interferometric gas monitoring and leak detection sensor shown in Fig. 1. The output of the sensor is an interference fringe pattern that is a function of the gas density, and commensurate index

  6. CMsearch: simultaneous exploration of protein sequence space and structure space improves not only protein homology detection but also protein structure prediction.

    Science.gov (United States)

    Cui, Xuefeng; Lu, Zhiwu; Wang, Sheng; Jing-Yan Wang, Jim; Gao, Xin

    2016-06-15

    Protein homology detection, a fundamental problem in computational biology, is an indispensable step toward predicting protein structures and understanding protein functions. Despite the advances in recent decades on sequence alignment, threading and alignment-free methods, protein homology detection remains a challenging open problem. Recently, network methods that try to find transitive paths in the protein structure space demonstrate the importance of incorporating network information of the structure space. Yet, current methods merge the sequence space and the structure space into a single space, and thus introduce inconsistency in combining different sources of information. We present a novel network-based protein homology detection method, CMsearch, based on cross-modal learning. Instead of exploring a single network built from the mixture of sequence and structure space information, CMsearch builds two separate networks to represent the sequence space and the structure space. It then learns sequence-structure correlation by simultaneously taking sequence information, structure information, sequence space information and structure space information into consideration. We tested CMsearch on two challenging tasks, protein homology detection and protein structure prediction, by querying all 8332 PDB40 proteins. Our results demonstrate that CMsearch is insensitive to the similarity metrics used to define the sequence and the structure spaces. By using HMM-HMM alignment as the sequence similarity metric, CMsearch clearly outperforms state-of-the-art homology detection methods and the CASP-winning template-based protein structure prediction methods. Our program is freely available for download from http://sfb.kaust.edu.sa/Pages/Software.aspx : xin.gao@kaust.edu.sa Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

  7. The bistatic radar capabilities of the Medicina radiotelescopes in space debris detection and tracking

    Science.gov (United States)

    Montebugnoli, S.; Pupillo, G.; Salerno, E.; Pluchino, S.; di Martino, M.

    2010-03-01

    An accurate measurement of the position and trajectory of the space debris fragments is of primary importance for the characterization of the orbital debris environment. The Medicina Radioastronomical Station is a radio observation facility that is here proposed as receiving part of a ground-based space surveillance system for detecting and tracking space debris at different orbital regions (from Low Earth Orbits up to Geostationary Earth Orbits). The proposed system consists of two bistatic radars formed by the existing Medicina receiving antennas coupled with appropriate transmitters. This paper focuses on the current features and future technical development of the receiving part of the observational setup. Outlines of possible transmitting systems will also be given together with the evaluation of the observation strategies achievable with the proposed facilities.

  8. Simple Signal Detection Algorithm for 4+12+16 APSK in Satellite and Space Communications

    Directory of Open Access Journals (Sweden)

    Jaeyoon Lee

    2010-09-01

    Full Text Available A 4+12+16 amplitude phase shift keying (APSK modulation outperforms other 32-APSK modulations in a nonlinear additive white Gaussian noise (AWGN channel because of its intrinsic robustness against AM/AM and AM/PM distortions caused by the nonlinear characteristics of a high-power amplifier. Thus, this modulation scheme has been adopted in the digital video broadcasting-satellite2 European standard. And it has been considered for high rate transmission of telemetry data on deep space communications in consultative committee for space data systems which provides a forum for discussion of common problems in the development and operation of space data systems. In this paper, we present an improved bits-to-symbol mapping scheme with a better bit error rate for a 4+12+16 APSK signal in a nonlinear AWGN channel and propose a simple signal detection algorithm for the 4+12+16 APSK from the presented bit mapping.

  9. Detection of IgE Reactivity to a Handful of Allergen Molecules in Early Childhood Predicts Respiratory Allergy in Adolescence

    Directory of Open Access Journals (Sweden)

    Magnus Wickman

    2017-12-01

    Interpretations: IgE reactivity to a few allergen molecules early in life identifies children with a high risk of asthma and/or rhinitis at 16 years. These findings will be of importance for developing preventive strategies for asthma and rhinitis in children.

  10. [Detection of the functionally active domains in the molecule of the lethal factor of the anthrax exotoxin].

    Science.gov (United States)

    Noskov, A N; Kravchenko, T B; Noskova, V P

    1996-01-01

    Three functional domains were revealed in the molecule of the lethal factor of B. anthracis. They are located in the linear structure of the molecula as follows: the associative domain occupies the area from Lys39 to Met242, the stabilizing domain from Leu517 to Lys614, and the effector domain still further to the COOH-terminal Lys mino acid.

  11. Detecting 3D Vegetation Structure with the Galileo Space Probe: Can a Distant Probe Detect Vegetation Structure on Earth?

    Directory of Open Access Journals (Sweden)

    Christopher E Doughty

    Full Text Available Sagan et al. (1993 used the Galileo space probe data and first principles to find evidence of life on Earth. Here we ask whether Sagan et al. (1993 could also have detected whether life on Earth had three-dimensional structure, based on the Galileo space probe data. We reanalyse the data from this probe to see if structured vegetation could have been detected in regions with abundant photosynthetic pigments through the anisotropy of reflected shortwave radiation. We compare changing brightness of the Amazon forest (a region where Sagan et al. (1993 noted a red edge in the reflectance spectrum, indicative of photosynthesis as the planet rotates to a common model of reflectance anisotropy and found measured increase of surface reflectance of 0.019 ± 0.003 versus a 0.007 predicted from only anisotropic effects. We hypothesize the difference was due to minor cloud contamination. However, the Galileo dataset had only a small change in phase angle (sun-satellite position which reduced the observed anisotropy signal and we demonstrate that theoretically if the probe had a variable phase angle between 0-20°, there would have been a much larger predicted change in surface reflectance of 0.1 and under such a scenario three-dimensional vegetation structure on Earth could possibly have been detected. These results suggest that anisotropic effects may be useful to help determine whether exoplanets have three-dimensional vegetation structure in the future, but that further comparisons between empirical and theoretical results are first necessary.

  12. Detecting 3D Vegetation Structure with the Galileo Space Probe: Can a Distant Probe Detect Vegetation Structure on Earth?

    Science.gov (United States)

    Doughty, Christopher E; Wolf, Adam

    2016-01-01

    Sagan et al. (1993) used the Galileo space probe data and first principles to find evidence of life on Earth. Here we ask whether Sagan et al. (1993) could also have detected whether life on Earth had three-dimensional structure, based on the Galileo space probe data. We reanalyse the data from this probe to see if structured vegetation could have been detected in regions with abundant photosynthetic pigments through the anisotropy of reflected shortwave radiation. We compare changing brightness of the Amazon forest (a region where Sagan et al. (1993) noted a red edge in the reflectance spectrum, indicative of photosynthesis) as the planet rotates to a common model of reflectance anisotropy and found measured increase of surface reflectance of 0.019 ± 0.003 versus a 0.007 predicted from only anisotropic effects. We hypothesize the difference was due to minor cloud contamination. However, the Galileo dataset had only a small change in phase angle (sun-satellite position) which reduced the observed anisotropy signal and we demonstrate that theoretically if the probe had a variable phase angle between 0-20°, there would have been a much larger predicted change in surface reflectance of 0.1 and under such a scenario three-dimensional vegetation structure on Earth could possibly have been detected. These results suggest that anisotropic effects may be useful to help determine whether exoplanets have three-dimensional vegetation structure in the future, but that further comparisons between empirical and theoretical results are first necessary.

  13. Combined Dimensionality Reduction in Search and Detection Spaces via Diffusion Mapping

    Science.gov (United States)

    Romanov, Dmitri; Smith, Stanley; Brady, John; Coifman, Ronald; Levis, Robert

    2008-03-01

    Strong-field control settings involve highly nonlinear processes. Typically, both search and detection spaces are high-dimensional (with dimension ˜100 each). This poses considerable problems to analysis and interpretation of the process-related data. Here, we use the recently developed nonlinear statistical method of diffusion mapping to effectively reduce the combined dimensionality of the search and detection space and to sample essential patterns in the lower-dimensional representation. The diffusion maps are constructed and analyzed for the case study of maximizing integrated intensity in a second harmonic generation experiment. The use of a sampling set of 1000 random pulses in the diffusion mapping is sufficient for effective dimensionality reduction and for revealing the inherent structure of the process-related data. Extrapolation of the low-dimensional diffusion-space pattern helps indicate the area in the search space that is most amenable to effective optimization. The diffusion-mapping algorithm is sufficiently fast and robust that may make it a valuable preprocessing tool for optimal pulse searching.

  14. Detection of macromolecules in desert cyanobacteria mixed with a lunar mineral analogue after space simulations.

    Science.gov (United States)

    Baqué, Mickael; Verseux, Cyprien; Rabbow, Elke; de Vera, Jean-Pierre Paul; Billi, Daniela

    2014-09-01

    In the context of future exposure missions in Low Earth Orbit and possibly on the Moon, two desert strains of the cyanobacterium Chroococcidiopsis, strains CCMEE 029 and 057, mixed or not with a lunar mineral analogue, were exposed to fractionated fluencies of UVC and polychromatic UV (200-400 nm) and to space vacuum. These experiments were carried out within the framework of the BIOMEX (BIOlogy and Mars EXperiment) project, which aims at broadening our knowledge of mineral-microorganism interaction and the stability/degradation of their macromolecules when exposed to space and simulated Martian conditions. The presence of mineral analogues provided a protective effect, preserving survivability and integrity of DNA and photosynthetic pigments, as revealed by testing colony-forming abilities, performing PCR-based assays and using confocal laser scanning microscopy. In particular, DNA and pigments were still detectable after 500 kJ/m(2) of polychromatic UV and space vacuum (10(-4) Pa), corresponding to conditions expected during one-year exposure in Low Earth Orbit on board the EXPOSE-R2 platform in the presence of 0.1 % Neutral Density (ND) filter. After exposure to high UV fluencies (800 MJ/m(2)) in the presence of minerals, however, altered fluorescence emission spectrum of the photosynthetic pigments were detected, whereas DNA was still amplified by PCR. The present paper considers the implications of such findings for the detection of biosignatures in extraterrestrial conditions and for putative future lunar missions.

  15. Grouped fuzzy SVM with EM-based partition of sample space for clustered microcalcification detection.

    Science.gov (United States)

    Wang, Huiya; Feng, Jun; Wang, Hongyu

    2017-07-20

    Detection of clustered microcalcification (MC) from mammograms plays essential roles in computer-aided diagnosis for early stage breast cancer. To tackle problems associated with the diversity of data structures of MC lesions and the variability of normal breast tissues, multi-pattern sample space learning is required. In this paper, a novel grouped fuzzy Support Vector Machine (SVM) algorithm with sample space partition based on Expectation-Maximization (EM) (called G-FSVM) is proposed for clustered MC detection. The diversified pattern of training data is partitioned into several groups based on EM algorithm. Then a series of fuzzy SVM are integrated for classification with each group of samples from the MC lesions and normal breast tissues. From DDSM database, a total of 1,064 suspicious regions are selected from 239 mammography, and the measurement of Accuracy, True Positive Rate (TPR), False Positive Rate (FPR) and EVL = TPR* 1-FPR are 0.82, 0.78, 0.14 and 0.72, respectively. The proposed method incorporates the merits of fuzzy SVM and multi-pattern sample space learning, decomposing the MC detection problem into serial simple two-class classification. Experimental results from synthetic data and DDSM database demonstrate that our integrated classification framework reduces the false positive rate significantly while maintaining the true positive rate.

  16. A modular CUDA-based framework for scale-space feature detection in video streams

    International Nuclear Information System (INIS)

    Kinsner, M; Capson, D; Spence, A

    2010-01-01

    Multi-scale image processing techniques enable extraction of features where the size of a feature is either unknown or changing, but the requirement to process image data at multiple scale levels imposes a substantial computational load. This paper describes the architecture and emerging results from the implementation of a GPGPU-accelerated scale-space feature detection framework for video processing. A discrete scale-space representation is generated for image frames within a video stream, and multi-scale feature detection metrics are applied to detect ridges and Gaussian blobs at video frame rates. A modular structure is adopted, in which common feature extraction tasks such as non-maximum suppression and local extrema search may be reused across a variety of feature detectors. Extraction of ridge and blob features is achieved at faster than 15 frames per second on video sequences from a machine vision system, utilizing an NVIDIA GTX 480 graphics card. By design, the framework is easily extended to additional feature classes through the inclusion of feature metrics to be applied to the scale-space representation, and using common post-processing modules to reduce the required CPU workload. The framework is scalable across multiple and more capable GPUs, and enables previously intractable image processing at video frame rates using commodity computational hardware.

  17. A systematic exploration of the micro-blog feature space for teens stress detection.

    Science.gov (United States)

    Zhao, Liang; Li, Qi; Xue, Yuanyuan; Jia, Jia; Feng, Ling

    2016-01-01

    In the modern stressful society, growing teenagers experience severe stress from different aspects from school to friends, from self-cognition to inter-personal relationship, which negatively influences their smooth and healthy development. Being timely and accurately aware of teenagers psychological stress and providing effective measures to help immature teenagers to cope with stress are highly valuable to both teenagers and human society. Previous work demonstrates the feasibility to sense teenagers' stress from their tweeting contents and context on the open social media platform-micro-blog. However, a tweet is still too short for teens to express their stressful status in a comprehensive way. Considering the topic continuity from the tweeting content to the follow-up comments and responses between the teenager and his/her friends, we combine the content of comments and responses under the tweet to supplement the tweet content. Also, such friends' caring comments like "what happened?", "Don't worry!", "Cheer up!", etc. provide hints to teenager's stressful status. Hence, in this paper, we propose to systematically explore the micro-blog feature space, comprised of four kinds of features [tweeting content features (FW), posting features (FP), interaction features (FI), and comment-response features (FC) between teenagers and friends] for teenager' stress category and stress level detection. We extract and analyze these feature values and their impacts on teens stress detection. We evaluate the framework through a real user study of 36 high school students aged 17. Different classifiers are employed to detect potential stress categories and corresponding stress levels. Experimental results show that all the features in the feature space positively affect stress detection, and linguistic negative emotion, proportion of negative sentences, friends' caring comments and teen's reply rate play more significant roles than the rest features. Micro-blog platform provides

  18. Quantum tunneling in real space: Tautomerization of single porphycene molecules on the (111) surface of Cu, Ag, and Au

    Science.gov (United States)

    Kumagai, Takashi; Ladenthin, Janina N.; Litman, Yair; Rossi, Mariana; Grill, Leonhard; Gawinkowski, Sylwester; Waluk, Jacek; Persson, Mats

    2018-03-01

    Tautomerization in single porphycene molecules is investigated on Cu(111), Ag(111), and Au(111) surfaces by a combination of low-temperature scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. It is revealed that the trans configuration is the thermodynamically stable form of porphycene on Cu(111) and Ag(111), whereas the cis configuration occurs as a meta-stable form. The trans → cis or cis → trans conversion on Cu(111) can be induced in an unidirectional fashion by injecting tunneling electrons from the STM tip or heating the surface, respectively. We find that the cis ↔ cis tautomerization on Cu(111) occurs spontaneously via tunneling, verified by the negligible temperature dependence of the tautomerization rate below ˜23 K. Van der Waals corrected DFT calculations are used to characterize the adsorption structures of porphycene and to map the potential energy surface of the tautomerization on Cu(111). The calculated barriers are too high to be thermally overcome at cryogenic temperatures used in the experiment and zero-point energy corrections do not change this picture, leaving tunneling as the most likely mechanism. On Ag(111), the reversible trans ↔ cis conversion occurs spontaneously at 5 K and the cis ↔ cis tautomerization rate is much higher than on Cu(111), indicating a significantly smaller tautomerization barrier on Ag(111) due to the weaker interaction between porphycene and the surface compared to Cu(111). Additionally, the STM experiments and DFT calculations reveal that tautomerization on Cu(111) and Ag(111) occurs with migration of porphycene along the surface; thus, the translational motion couples with the tautomerization coordinate. On the other hand, the trans and cis configurations are not discernible in the STM image and no tautomerization is observed for porphycene on Au(111). The weak interaction of porphycene with Au(111) is closest to the gas-phase limit and therefore the absence

  19. Topography of signaling molecules as detected by electron microscopy on plasma membrane sheets isolated from non-adherent mast cells

    Czech Academy of Sciences Publication Activity Database

    Lebduška, Pavel; Korb, Jan; Tůmová, Magda; Heneberg, Petr; Dráber, Petr

    2007-01-01

    Roč. 328, 1-2 (2007), s. 139-151 ISSN 0022-1759 R&D Projects: GA MŠk 1M0506; GA ČR GD204/05/H023; GA ČR GA301/06/0361 Institutional research plan: CEZ:AV0Z50520514 Keywords : plasma membrane * electron microscopy * topography of signaling molecules Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.947, year: 2007

  20. Detection of cold gas releases in space via low energy neutral atom imaging

    International Nuclear Information System (INIS)

    McComas, D.J.; Funsten, H.O.; Moore, K.R.; Scime, E.E.; Thomsen, M.F.

    1993-01-01

    Low energy neutral atoms (LENAs) are produced in space plasmas by charge exchange between the ambient magnetospheric plasma ions and cold neutral atoms. Under normal conditions these cold neutrals come from the terrestrial geocorona, a shroud of few-eV hydrogen atoms surrounding the Earth. As a consequence of this charge exchange, it has become possible to remotely image many regions of the magnetosphere for the first time utilizing recently developed LENA imaging technology. In addition to the natural hydrogen geocorona, conventional explosions and maneuvering thruster firings can also introduce large amounts of cold gas into the space environment. In this paper the authors examine whether such potentially clandestine activities could also be remotely observed for the first time via LENA imaging. First, they examine the fluxes of LENAs produced in the space environment from a conventional explosion. Then they review the present state of the art in the emerging field of LENA detection and imaging. Recent work has shown that LENAs can be imaged by first converting the neutrals to ions with ultra-thin (10s of angstrom) foils and then electrostatically analyzing these newly created ions to reject the large (> 10 10 cm -2 s -1 ) UV background to which the low energy detectors are sensitive. They conclude that the sensitivities for present LENA imager designs may be just adequate for detecting some man-made releases. With additional improvements in LENA detection capabilities, this technique could become an important new method for monitoring for conventional explosions, as well as other man-made neutral releases, in the space environment

  1. Molecule Matters

    Indian Academy of Sciences (India)

    is a very stable and inert molecule due to the formation of a triple bond between the two atoms. Surpris- ingly isoelectronic molecules are quite reactive making dinitrogen very useful and unique. Dinitrogen (N. 2. ) is such an innocuous molecule that you might not think it worthy of special attention. We take this molecule for.

  2. Silicon-bearing molecules in the shock L1157-B1: first detection of SiS around a Sun-like protostar

    Science.gov (United States)

    Podio, L.; Codella, C.; Lefloch, B.; Balucani, N.; Ceccarelli, C.; Bachiller, R.; Benedettini, M.; Cernicharo, J.; Faginas-Lago, N.; Fontani, F.; Gusdorf, A.; Rosi, M.

    2017-09-01

    The shock L1157-B1 driven by the low-mass protostar L1157-mm is a unique environment to investigate the chemical enrichment due to molecules released from dust grains. IRAM-30m and Plateau de Bure Interferometer observations allow a census of Si-bearing molecules in L1157-B1. We detect SiO and its isotopologues and, for the first time in a shock, SiS. The strong gradient of the [SiO/SiS] abundance ratio across the shock (from ≥180 to ˜25) points to a different chemical origin of the two species. SiO peaks where the jet impacts the cavity walls ([SiO/H2] ˜ 10-6), indicating that SiO is directly released from grains or rapidly formed from released Si in the strong shock occurring at this location. In contrast, SiS is only detected at the head of the cavity opened by previous ejection events ([SiS/H2] ˜ 2 × 10-8). This suggests that SiS is not directly released from the grain cores but instead should be formed through slow gas-phase processes using part of the released silicon. This finding shows that Si-bearing molecules can be useful to distinguish regions where grains or gas-phase chemistry dominates.

  3. Detectability of CO2 flux signals by a space-based lidar mission

    Science.gov (United States)

    Hammerling, Dorit M.; Kawa, S. Randolph; Schaefer, Kevin; Doney, Scott; Michalak, Anna M.

    2015-03-01

    Satellite observations of carbon dioxide (CO2) offer novel and distinctive opportunities for improving our quantitative understanding of the carbon cycle. Prospective observations include those from space-based lidar such as the active sensing of CO2 emissions over nights, days, and seasons (ASCENDS) mission. Here we explore the ability of such a mission to detect regional changes in CO2 fluxes. We investigate these using three prototypical case studies, namely, the thawing of permafrost in the northern high latitudes, the shifting of fossil fuel emissions from Europe to China, and changes in the source/sink characteristics of the Southern Ocean. These three scenarios were used to design signal detection studies to investigate the ability to detect the unfolding of these scenarios compared to a baseline scenario. Results indicate that the ASCENDS mission could detect the types of signals investigated in this study, with the caveat that the study is based on some simplifying assumptions. The permafrost thawing flux perturbation is readily detectable at a high level of significance. The fossil fuel emission detectability is directly related to the strength of the signal and the level of measurement noise. For a nominal (lower) fossil fuel emission signal, only the idealized noise-free instrument test case produces a clearly detectable signal, while experiments with more realistic noise levels capture the signal only in the higher (exaggerated) signal case. For the Southern Ocean scenario, differences due to the natural variability in the El Niño-Southern Oscillation climatic mode are primarily detectable as a zonal increase.

  4. Fire Detection Using tin Oxide Gas Sensors Installed in an Indoor Space

    Science.gov (United States)

    Shibata, Shin-Ichi; Higashino, Tsubasa; Sawada, Ayako; Oyabu, Takashi; Takei, Yoshinori; Nanto, Hidehito; Toko, Kiyoshi

    Many lives and facilities were lost by fire. Especially, there are many damages to elderly, toddlers and babies. In Japan, number of deaths over 65 years old reached to 53% in 2004. Number of over 81 years olds went to 20%. It takes for the elderly person more time to sense fire and also to evacuate to safe places. Although it is important to prevent the fire, it also needs to inform the fire breaking as early as possible. Human sense decreases with age and it is difficult to perceive the fire at an early stage. It is desired to develop a higher sensitive element for fire and its system which can detect fire at an early stage. In this experiment, tin oxide gas sensors were adopted to detect a smoldering fire at the early stage. Most common case of fire is the smoldering fire. The reliability of the sensor is higher and it is adopted in a gas alarm detector. The sensor can also detect slight amount of odor molecule. In our previous experiment, it became obvious that it was better to install the sensor to the ceiling to detect odor components generating from smoldering fire. Therefore, five sensors were installed in the ceiling away from each other and the method to detect the fire was examined. As a result, a characteristic was newly derived by adding the sensor outputs for one minute. The sensor output was input every 0.1s. The characteristic is called as the integrated characteristic. After that, the differential characteristic was derived using the integrated characteristic. The fire was determined using the differential characteristics. The materials causing a smoldering fire were woodchip, wallpaper and carpet as subjects. The system could detect the fire in several minutes for whole materials. The sensor is effective to detect the smoldering fire at an early stage. It is necessary to detect a cigarette smoke to distinguish as non fire. In this study, the discrimination was also examined using a quadratic function (ax2+b). The coefficients a and b were

  5. Action detection by double hierarchical multi-structure space-time statistical matching model

    Science.gov (United States)

    Han, Jing; Zhu, Junwei; Cui, Yiyin; Bai, Lianfa; Yue, Jiang

    2018-03-01

    Aimed at the complex information in videos and low detection efficiency, an actions detection model based on neighboring Gaussian structure and 3D LARK features is put forward. We exploit a double hierarchical multi-structure space-time statistical matching model (DMSM) in temporal action localization. First, a neighboring Gaussian structure is presented to describe the multi-scale structural relationship. Then, a space-time statistical matching method is proposed to achieve two similarity matrices on both large and small scales, which combines double hierarchical structural constraints in model by both the neighboring Gaussian structure and the 3D LARK local structure. Finally, the double hierarchical similarity is fused and analyzed to detect actions. Besides, the multi-scale composite template extends the model application into multi-view. Experimental results of DMSM on the complex visual tracker benchmark data sets and THUMOS 2014 data sets show the promising performance. Compared with other state-of-the-art algorithm, DMSM achieves superior performances.

  6. Detecting the solution space of vertex cover by mutual determinations and backbones.

    Science.gov (United States)

    Wei, Wei; Zhang, Renquan; Guo, Binghui; Zheng, Zhiming

    2012-07-01

    To solve the combinatorial optimization problems, especially the minimal Vertex-cover problem with high efficiency, is a significant task in theoretical computer science and many other subjects. Aiming at detecting the solution space of Vertex-cover, a new structure named mutual-determination is defined and discovered for Vertex-cover on general graphs, which results in the emergence of strong correlations among the unfrozen nodes. Based on the backbones and mutual-determinations with node ranks by leaf removal, we propose a Mutual-determination and Backbone Evolution Algorithm to achieve the reduced solution graph, which provides a graphical expression of the solution space of Vertex-cover. By this algorithm, the whole solution space and detailed structures such as backbones can be obtained strictly when there is no leaf-removal core on the given graph. Compared with the current algorithms, the Mutual-determination and Backbone Evolution Algorithm performs as well as the replica symmetry one in a certain interval but has a small gap higher than the replica symmetric breaking one and has a relatively small error for the exact results. The algorithm with the mutual-determination provides a new viewpoint to solve Vertex-cover and understand the organizations of the solution spaces, and the reduced solution graph gives an alternative way to catch detailed information of the ground/steady states.

  7. Coupling of background reduction with rolling circle amplification for highly sensitive protein detection via terminal protection of small molecule-linked DNA.

    Science.gov (United States)

    Wang, Qiong; Jiang, Bingying; Xie, Jiaqing; Xiang, Yun; Yuan, Ruo; Chai, Yaqin

    2013-10-07

    In this work, by coupling background current reduction with rolling circle amplification (RCA), we describe the development of an ultrasensitive electrochemical sensing method for protein detection based on a small molecule-linked DNA terminal protection strategy. Our detection platform employs a typical streptavidin (STV)-biotin interaction system. Biotin-linked single-stranded DNA (SH-ssDNA-biotin) is self-assembled on a gold electrode to capture the target protein, STV. The binding of STV with the biotin small molecule recognition element protects the SH-ssDNA-biotin against hydrolysis by exonuclease I (Exo I), while the unbound SH-ssDNA-biotin is effectively hydrolyzed and removed from the electrode surface. The bound STV further interacts with long, RCA-amplified biotin DNAs to facilitate the adsorption of numerous electroactive reporters, hexaammineruthenium(III) chloride (RuHex) via electrostatic interactions, which results in significantly amplified signals for the quantitative determination of STV. Moreover, the removal of the unbound SH-ssDNA-biotin probes from the sensing electrode obviates the accumulation of RuHex and leads to a highly minimized background current. The simultaneous RCA signal amplification and background current reduction is expected to significantly enhance the signal-to-noise ratio and to achieve ultrahigh sensitivity. The results reveal that the developed strategy provides a low detection limit of 0.4 pM with high selectivity.

  8. Direct detection of hundreds of exoplanets with a space-based mid-infrared interferometer

    Science.gov (United States)

    Quanz, S. P.; Kammerer, J.

    2017-09-01

    One of the long-term goals of exoplanet research is the (atmospheric) characterization of a sizeable sample of small, terrestrial planets in order to assess their potential habitability. In this context it is important to quantitatively assess the scientific return of various mission concepts in order to derive robust science requirements. While transit and secondary eclipse spectroscopy may provide data on a few systems, it seems questionable whether a larger planet sample can be investigated given that most planets do not transit in front of their host stars. Hence, direct detection methods may be required. Here we predict the exoplanet yield of a space-based mid-infrared nulling interferometer (akin to the Darwin mission concept) using a catalog of nearby stars and the planet occurrence rates found by NASA's Kepler mission. We find that a mission with the technical specifications of Darwin could detect >300 exoplanets (with radii between 0.5 and 6 Earth radii). Roughly 85 planets have radii between 0.5 and 1.75 Earth radii and equilibrium temperatures between 200 and 450 K and are prime targets for spectroscopic follow-up observations in the second phase of the mission investigating their potential habitability. Higher planet yields can be realized by further optimizing the observing strategy. We also compare the baseline planet yield of a space-based mid-infrared interferometer to that of a large space-based optical/IR telescope. We conclude that a Darwin-like mission concept should be put back on the long-term agenda of the exoplanet community and related space agencies.

  9. The local dark matter phase-space density and impact on WIMP direct detection

    International Nuclear Information System (INIS)

    Catena, Riccardo; Ullio, Piero

    2012-01-01

    We present a new determination of the local dark matter phase-space density. This result is obtained implementing, in the limit of isotropic velocity distribution and spherical symmetry, Eddington's inversion formula, which links univocally the dark matter distribution function to the density profile, and applying, within a Bayesian framework, a Markov Chain Monte Carlo algorithm to sample mass models for the Milky Way against a broad and variegated sample of dynamical constraints. We consider three possible choices for the dark matter density profile, namely the Einasto, NFW and Burkert profiles, finding that the velocity dispersion, which characterizes the width in the distribution, tends to be larger for the Burkert case, while the escape velocity depends very weakly on the profile, with the mean value we obtain being in very good agreement with estimates from stellar kinematics. The derived dark matter phase-space densities differ significantly — most dramatically in the high velocity tails — from the model usually taken as a reference in dark matter detection studies, a Maxwell-Boltzmann distribution with velocity dispersion fixed in terms of the local circular velocity and with a sharp truncation at a given value of the escape velocity. We discuss the impact of astrophysical uncertainties on dark matter scattering rates and direct detection exclusion limits, considering a few sample cases and showing that the most sensitive ones are those for light dark matter particles and for particles scattering inelastically. As a general trend, regardless of the assumed profile, when adopting a self-consistent phase-space density, we find that rates are larger, and hence exclusion limits stronger, than with the standard Maxwell-Boltzmann approximation. Tools for applying our result on the local dark matter phase-space density to other dark matter candidates or experimental setups are provided

  10. Current Progresses of Midass: Microbial Detection in Air System for Space

    Science.gov (United States)

    Abaibou, Hafid; Lasseur, Christophe; Mabilat, Claude; Storrs-Mabilat, Michele; Guy, Michel; Raffestin, Stephanie; Sole Bosquet, Jaume

    For the long term manned missions, microbial contamination is a major risk for crew members and hardware. This risk has first been documented by Russian scientists then by other organizations as a consequence of the contamination of metabolic consumables (water, air), and also the hardware degradation. Rapid molecular biology techniques offer an attractive alternative to traditional culture-based methods. They allow fast time to results for contamination detection and quick implementation of appropriate corrective action when required. However, to date, there are no such available system due to the technical challenges required to meet the sensitivity and specificity needs of the test and the requirement for full automation, from sampling to results interpretation. In response to this, over the last decade, the European Space Agency (ESA) and bioMérieux initiated a co-development of MIDASS, the world’s first fully automated system for the monitoring of the environmental microbial load in confined spaces, including clean rooms and hospital wards. The system is based on molecular technologies (sample preparation/amplification/detection) and enables rapid and simple determination of the microbiological contamination level in less than 3 hours. It relies on NASBA-amplification for the detection of selected micro-organisms (indicators or pathogens) at determined risk-levels (200 and 1 CFU /m3 air, respectively). Successful progresses were recently made for the space-application workpackage of this project: a lab-on-a-card design for air-testing in a first scope was endorsed by a successful ESA Preliminary Design Review, paving the way to spatialization steps (phases C and D). Data will be presented with regards to system design and biological performances.

  11. Study on detection of terrestrial and marine fractions in marine organic molecules by spectrophoto- and spectrofluorometric methods

    Science.gov (United States)

    Drozdowska, Violetta; Wróbel, Iwona; Piskozub, Jacek

    2017-04-01

    The sea surface is a highly productive and active interface between the sea and the atmosphere. Sea surface films are created by organic matter from sea and land sources and they dissipate due to loss of material at the sea surface, including microbial degradation, chemical and photo chemical processes, and loss due to absorption and adsorption onto particulates. However the surface microlayer is almost ubiquitous and cover most of the surface of the ocean, even under conditions of high turbulence. Surface active molecules (surfactants) present in the surface microlayer (SML) may modify the number of physical processes taking place there: among others they affect the depth of penetration of solar radiation and gas exchange. Therefore, research on the influence of surfactants on the sea surface properties become an important task, especially in coastal waters and in vicinity of the river mouths. Surfactants comprises a mixture of organic molecules rich in lipids, polymeric and humus whose proportions determine the various properties of the SML. A unique structure of the energy levels of the organic molecules results in a unique spectral distribution of the light intensity absorbed and emitted by the molecules. Hence, the absorption and fluorescence spectra of organic compounds may allow the identification of the sources of organic matter. Additionally, several absorption (E2:E3, S, SR) and fluorescence (fluorescence intensities at peaks: A, C, M, T, the ratio (M+T)/(A+C), HIX) indices help in describing the changes in molecular size and weight as well as composition of organic matter during the humification processes and caused by photobleaching and biodegradation. Investigations included the region of Gulf of Gdańsk, along a transect from the Vistula River outlet to open sea. The fluorescence and absorption measurements of the samples collected from a surface films and a subsurface layer (SS, a depth of 1 m) during three research cruises in Gulf of Gdańsk, the

  12. Exploration of Volatile Organic Molecules for Detection of the Brown Tree Snake and Other Non-Indigenous Species

    National Research Council Canada - National Science Library

    Nielsen, Bruce

    2004-01-01

    HQ PACAF submitted high ranked Environmental Safety and Occupational Health (ESOH) Need 1301, "Detect Brown Tree Snakes in Cargo and Craft to Prevent Spread to Other Areas of the Pacific and Mainland United States...

  13. Exploration of Volatile Organic Molecules for Detection of the Brown Tree Snake and Other Non-Indigenous Species

    National Research Council Canada - National Science Library

    Nielsen, Bruce

    2004-01-01

    ...." A reliable, portable, cost-effective device capable of detecting and locating the BTS in and around aircraft, ships, and cargo would greatly enhance the efforts to control the BTS and prevent...

  14. Detection and characterization of the tin dihydride (SnH2 and SnD2) molecule in the gas phase

    Science.gov (United States)

    Smith, Tony C.; Clouthier, Dennis J.

    2018-01-01

    The SnH2 and SnD2 molecules have been detected for the first time in the gas phase by laser-induced fluorescence (LIF) and emission spectroscopic techniques through the à 1B1-X ˜ 1A1 electronic transition. These reactive species were prepared in a pulsed electric discharge jet using (CH3)4Sn or SnH4/SnD4 precursors diluted in high pressure argon. Transitions to the electronic excited state of the jet-cooled molecules were probed with LIF, and the ground state energy levels were measured from single rovibronic level emission spectra. The LIF spectrum of SnD2 afforded sufficient rotational structure to determine the ground and excited state geometries: r0″ = 1.768 Å, θ0″ = 91.0°, r0' = 1.729 Å, θ0' = 122.9°. All of the observed LIF bands show evidence of a rotational-level-dependent predissociation process which rapidly decreases the fluorescence yield and lifetime with increasing rotational angular momentum in each excited vibronic level. This behavior is analogous to that observed in SiH2 and GeH2 and is suggested to lead to the formation of ground state tin atoms and hydrogen molecules.

  15. Effect of α variation on a prospective experiment to detect variation of me/mp in diatomic molecules

    International Nuclear Information System (INIS)

    Beloy, K.; Borschevsky, A.; Schwerdtfeger, P.; Flambaum, V. V.

    2011-01-01

    We consider the influence of variation in the fine structure constant α on a promising experiment proposed by DeMille et al. to search for variation in the electron-to-proton mass ratio μ using diatomic molecules [DeMille et al., Phys. Rev. Lett. 100, 043202 (2008)]. The proposed experiment involves spectroscopically probing the splitting between two nearly degenerate vibrational levels supported by different electronic potentials. Here we demonstrate that this splitting may be equally or more sensitive to variation in α as to variation in μ. For the anticipated experimental precision, this implies that the α variation may not be negligible, as previously assumed, and further suggests that the method could serve as a competitive means to search for α variation as well.

  16. Molecule nanoweaver

    Science.gov (United States)

    Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL; Diaz, Rocio [Chicago, IL; Vukovic, Lela [Westchester, IL

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  17. A hybrid color space for skin detection using genetic algorithm heuristic search and principal component analysis technique.

    Science.gov (United States)

    Maktabdar Oghaz, Mahdi; Maarof, Mohd Aizaini; Zainal, Anazida; Rohani, Mohd Foad; Yaghoubyan, S Hadi

    2015-01-01

    Color is one of the most prominent features of an image and used in many skin and face detection applications. Color space transformation is widely used by researchers to improve face and skin detection performance. Despite the substantial research efforts in this area, choosing a proper color space in terms of skin and face classification performance which can address issues like illumination variations, various camera characteristics and diversity in skin color tones has remained an open issue. This research proposes a new three-dimensional hybrid color space termed SKN by employing the Genetic Algorithm heuristic and Principal Component Analysis to find the optimal representation of human skin color in over seventeen existing color spaces. Genetic Algorithm heuristic is used to find the optimal color component combination setup in terms of skin detection accuracy while the Principal Component Analysis projects the optimal Genetic Algorithm solution to a less complex dimension. Pixel wise skin detection was used to evaluate the performance of the proposed color space. We have employed four classifiers including Random Forest, Naïve Bayes, Support Vector Machine and Multilayer Perceptron in order to generate the human skin color predictive model. The proposed color space was compared to some existing color spaces and shows superior results in terms of pixel-wise skin detection accuracy. Experimental results show that by using Random Forest classifier, the proposed SKN color space obtained an average F-score and True Positive Rate of 0.953 and False Positive Rate of 0.0482 which outperformed the existing color spaces in terms of pixel wise skin detection accuracy. The results also indicate that among the classifiers used in this study, Random Forest is the most suitable classifier for pixel wise skin detection applications.

  18. Comparison of Electrochemical Immunosensors and Aptasensors for Detection of Small Organic Molecules in Environment, Food Safety, Clinical and Public Security

    Directory of Open Access Journals (Sweden)

    Benoit Piro

    2016-02-01

    Full Text Available We review here the most frequently reported targets among the electrochemical immunosensors and aptasensors: antibiotics, bisphenol A, cocaine, ochratoxin A and estradiol. In each case, the immobilization procedures are described as well as the transduction schemes and the limits of detection. It is shown that limits of detections are generally two to three orders of magnitude lower for immunosensors than for aptasensors, due to the highest affinities of antibodies. No significant progresses have been made to improve these affinities, but transduction schemes were improved instead, which lead to a regular improvement of the limit of detections corresponding to ca. five orders of magnitude over these last 10 years. These progresses depend on the target, however.

  19. Raman spectroscopy as an effective screening method for detecting adulteration of milk with small nitrogen-rich molecules and sucrose.

    Science.gov (United States)

    Nieuwoudt, M K; Holroyd, S E; McGoverin, C M; Simpson, M C; Williams, D E

    2016-04-01

    Adulteration of milk for commercial gain is acknowledged as a serious issue facing the dairy industry. Several analytical techniques can be used to detect adulteration but they often require time-consuming sample preparation, expensive laboratory equipment, and highly skilled personnel. Here we show that Raman spectroscopy provides a simple, selective, and sensitive method for screening milk, specifically for small nitrogen-rich compounds, such as melamine, urea, ammonium sulfate, dicyandiamide, and for sucrose. Univariate and multivariate statistical methods were used to determine limits of detection and quantification from Raman spectra of milk spiked with 50 to 1,000 mg/L of the N-rich compounds and 0.25 to 4% sucrose. Partial least squares (PLS) calibration provided limit of detection minimum thresholds milk for these adulterants. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  20. Specific, sensitive, high-resolution detection of protein molecules in eukaryotic cells using metal-tagging transmission electron microscopy

    Science.gov (United States)

    Risco, Cristina; Sanmartín-Conesa, Eva; Tzeng, Wen-Pin; Frey, Teryl K.; Seybold, Volker; de Groot, Raoul J.

    2012-01-01

    Summary More than any other methodology, transmission electron microscopy (TEM) has contributed to our understanding of the architecture and organization of cells. With current detection limits approaching atomic resolution, it will ultimately become possible to ultrastructurally image intracellular macromolecular assemblies in situ. Presently, however, methods to unambiguously identify proteins within the crowded environment of the cell’s interior are lagging behind. We describe a novel approach, metal-tagging TEM (METTEM) that allows detection of intracellular proteins in mammalian cells with high specificity, exceptional sensitivity and at molecular scale resolution. In live cells treated with gold salts, proteins bearing a small metal-binding tag will form 1-nm gold nanoclusters, readily detectable in electron micrographs. The applicability and strength of METTEM is demonstrated by a study of Rubella virus replicase and capsid proteins, which revealed virus-induced cell structures not seen before. PMID:22579245

  1. Magnetic Iron Oxide Nanoparticles and a Polydiacetylene Coating to Create a Biocompatible and Stable Molecule for Use in Cancer Diagnostics and Early Detection in Molecular Medicine

    Science.gov (United States)

    Bhatnagar, Shweta

    Earlier cancer detection and diagnosis is essential to prevent cancer mortality in nanomedicine and nanotechnology. Fluorescence and magnetic signals provide a way for earlier detection through imaging systems. Magnetic iron oxide nanoparticles have a superparamagnetism feature that allows them to act as contrast agents that can be detected through a magnetic resonance imaging system. These iron oxide cores have a polymer coating around them to provide stability, prevent aggregation, and allow for biocompatibility within the body. In addition, these functional coatings can have ligands and peptides for detection and therapy purposes. One functional coating is a polydiacetylene coating due to its chromatic and optical properties. When polymerized, it has the ability to change color in the visible spectrum to blue (not a fluorescent signal) and when heated, it changes to a red color (fluorescent signal). This way a strong and stable layer is formed around the iron oxide cores. These coatings are placed on the iron cores using a modified dual solvent exchange method, in which DMSO is slowly replaced by water without the use of organic solvents previous used. In addition, these nanoparticles can then be PEGylated, which provides a more stable and water soluble compound in aqueous solutions. Measurements can be taken through dynamic light scattering for size distributions and zeta potential and the Nanodrop for absorbance. Ideal sizes are about 30 nm for MNPs. Moreover, for future directions, there can be more molecules attached to the coated layers to use for molecular detection and analysis.

  2. Molecular Signature of Pseudomonas aeruginosa with Simultaneous Nanomolar Detection of Quorum Sensing Signaling Molecules at a Boron-Doped Diamond Electrode

    Science.gov (United States)

    Buzid, Alyah; Shang, Fengjun; Reen, F. Jerry; Muimhneacháin, Eoin Ó.; Clarke, Sarah L.; Zhou, Lin; Luong, John H. T.; O'Gara, Fergal; McGlacken, Gerard P.; Glennon, Jeremy D.

    2016-07-01

    Electroanalysis was performed using a boron-doped diamond (BDD) electrode for the simultaneous detection of 2-heptyl-3-hydroxy-4-quinolone (PQS), 2-heptyl-4-hydroxyquinoline (HHQ) and pyocyanin (PYO). PQS and its precursor HHQ are two important signal molecules produced by Pseudomonas aeruginosa, while PYO is a redox active toxin involved in virulence and pathogenesis. This Gram-negative and opportunistic human pathogen is associated with a hospital-acquired infection particularly in patients with compromised immunity and is the primary cause of morbidity and mortality in cystic fibrosis (CF) patients. Early detection is crucial in the clinical management of this pathogen, with established infections entering a biofilm lifestyle that is refractory to conventional antibiotic therapies. Herein, a detection procedure was optimized and proven for the simultaneous detection of PYO, HHQ and PQS in standard mixtures, biological samples, and P. aeruginosa spiked CF sputum samples with remarkable sensitivity, down to nanomolar levels. Differential pulse voltammetry (DPV) scans were also applicable for monitoring the production of PYO, HHQ and PQS in P. aeruginosa PA14 over 8 h of cultivation. The simultaneous detection of these three compounds represents a molecular signature specific to this pathogen.

  3. Single-molecule detection of protein efflux from microorganisms using fluorescent single-walled carbon nanotube sensor arrays

    Science.gov (United States)

    Landry, Markita Patricia; Ando, Hiroki; Chen, Allen Y.; Cao, Jicong; Kottadiel, Vishal Isaac; Chio, Linda; Yang, Darwin; Dong, Juyao; Lu, Timothy K.; Strano, Michael S.

    2017-05-01

    A distinct advantage of nanosensor arrays is their ability to achieve ultralow detection limits in solution by proximity placement to an analyte. Here, we demonstrate label-free detection of individual proteins from Escherichia coli (bacteria) and Pichia pastoris (yeast) immobilized in a microfluidic chamber, measuring protein efflux from single organisms in real time. The array is fabricated using non-covalent conjugation of an aptamer-anchor polynucleotide sequence to near-infrared emissive single-walled carbon nanotubes, using a variable chemical spacer shown to optimize sensor response. Unlabelled RAP1 GTPase and HIV integrase proteins were selectively detected from various cell lines, via large near-infrared fluorescent turn-on responses. We show that the process of E. coli induction, protein synthesis and protein export is highly stochastic, yielding variability in protein secretion, with E. coli cells undergoing division under starved conditions producing 66% fewer secreted protein products than their non-dividing counterparts. We further demonstrate the detection of a unique protein product resulting from T7 bacteriophage infection of E. coli, illustrating that nanosensor arrays can enable real-time, single-cell analysis of a broad range of protein products from various cell types.

  4. Membrane Active Small Molecules Show Selective Broad Spectrum Antibacterial Activity with No Detectable Resistance and Eradicate Biofilms.

    Science.gov (United States)

    Hoque, Jiaul; Konai, Mohini M; Gonuguntla, Spandhana; Manjunath, Goutham B; Samaddar, Sandip; Yarlagadda, Venkateswarlu; Haldar, Jayanta

    2015-07-23

    Treating bacterial biofilms with conventional antibiotics is limited due to ineffectiveness of the drugs and higher propensity to develop bacterial resistance. Development of new classes of antibacterial therapeutics with alternative mechanisms of action has become imperative. Herein, we report the design, synthesis, and biological evaluations of novel membrane-active small molecules featuring two positive charges, four nonpeptidic amide groups, and variable hydrophobic/hydrophilic (amphiphilic) character. The biocides synthesized via a facile methodology not only displayed good antibacterial activity against wild-type bacteria but also showed high activity against various drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and β-lactam-resistant Klebsiella pneumoniae. Further, these biocides not only inhibited the formation of biofilms but also disrupted the established S. aureus and E. coli biofilms. The membrane-active biocides hindered the propensity to develop bacterial resistance. Moreover, the biocides showed negligible toxicity against mammalian cells and thus bear potential to be used as therapeutic agents.

  5. Extending the Generalised Pareto Distribution for Novelty Detection in High-Dimensional Spaces.

    Science.gov (United States)

    Clifton, David A; Clifton, Lei; Hugueny, Samuel; Tarassenko, Lionel

    2014-01-01

    Novelty detection involves the construction of a "model of normality", and then classifies test data as being either "normal" or "abnormal" with respect to that model. For this reason, it is often termed one-class classification. The approach is suitable for cases in which examples of "normal" behaviour are commonly available, but in which cases of "abnormal" data are comparatively rare. When performing novelty detection, we are typically most interested in the tails of the normal model, because it is in these tails that a decision boundary between "normal" and "abnormal" areas of data space usually lies. Extreme value statistics provides an appropriate theoretical framework for modelling the tails of univariate (or low-dimensional) distributions, using the generalised Pareto distribution (GPD), which can be demonstrated to be the limiting distribution for data occurring within the tails of most practically-encountered probability distributions. This paper provides an extension of the GPD, allowing the modelling of probability distributions of arbitrarily high dimension, such as occurs when using complex, multimodel, multivariate distributions for performing novelty detection in most real-life cases. We demonstrate our extension to the GPD using examples from patient physiological monitoring, in which we have acquired data from hospital patients in large clinical studies of high-acuity wards, and in which we wish to determine "abnormal" patient data, such that early warning of patient physiological deterioration may be provided.

  6. Papaya Tree Detection with UAV Images Using a GPU-Accelerated Scale-Space Filtering Method

    Directory of Open Access Journals (Sweden)

    Hao Jiang

    2017-07-01

    Full Text Available The use of unmanned aerial vehicles (UAV can allow individual tree detection for forest inventories in a cost-effective way. The scale-space filtering (SSF algorithm is commonly used and has the capability of detecting trees of different crown sizes. In this study, we made two improvements with regard to the existing method and implementations. First, we incorporated SSF with a Lab color transformation to reduce over-detection problems associated with the original luminance image. Second, we ported four of the most time-consuming processes to the graphics processing unit (GPU to improve computational efficiency. The proposed method was implemented using PyCUDA, which enabled access to NVIDIA’s compute unified device architecture (CUDA through high-level scripting of the Python language. Our experiments were conducted using two images captured by the DJI Phantom 3 Professional and a most recent NVIDIA GPU GTX1080. The resulting accuracy was high, with an F-measure larger than 0.94. The speedup achieved by our parallel implementation was 44.77 and 28.54 for the first and second test image, respectively. For each 4000 × 3000 image, the total runtime was less than 1 s, which was sufficient for real-time performance and interactive application.

  7. Improved galvanic replacement growth of Ag microstructures on Cu micro-grid for enhanced SERS detection of organic molecules

    International Nuclear Information System (INIS)

    Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

    2016-01-01

    Galvanic growth of Ag nano/micro-structures on Cu micro-grid was systematically studied for surface-enhanced Raman scattering (SERS) applications. Detailed characterizations via FE-SEM and HR-TEM showed that processing parameters, (reaction time, Ag + concentration, and PVP addition) all substantially affect thermodynamics/kinetics of the replacement reaction to yield substrates of significantly different microstructures/homogeneities and thus varied SERS performances (sensitivity, enhancement factor, and reproducibility) of the Ag substrates in the detection of R6G analyte. PVP as an additive was shown to notably alter nucleation/growth behaviors of the Ag crystals and promote the deposition of dense and uniform Ag films of nearly monodisperse polyhedrons/nanoplates through suppressing dendrites crystallization. Under optimized synthesis (50 mM of Ag + , 30 s of reaction, and 700 wt.% of PVP), Ag substrates exhibiting a high Raman signal enhancement factor of ~ 1.1 × 10 6 and a low relative standard deviation of ~ 0.13 in the repeated detection of 10 μM R6G were obtained. The facile deposition and excellent performance reported in this work may allow the Ag microstructures to find wider SERS applications. Moreover, growth mechanisms of the different Ag nano/micro-structures were discussed based on extensive FE-SEM and HR-TEM analysis. - Highlights: • A facile synthetic technique of growing SERS active Ag substrates onto Cu micro-grid has been systematically studied. • Changing processing parameters has yielded Ag crystals of various morphologies and SERS performances. • PVP additive was observed to suppress Ag dendrite crystallization for nearly monodispersed Ag polyhedrons/nanoplates. • PVP modified SERS substrate exhibits excellent EF and RSD values in the repeated detection of 10 μM R6G analyte.

  8. The Amazing Molecule Race: A WebQuest for 8th Grade Science

    Science.gov (United States)

    Soehl, Diana; Moats, S. J.; Langston, G. I.

    2009-01-01

    Did you ever wonder if life exists beyond Earth? The molecules that helped make up you and your friends are the same floating in outer space! The Race is ON to discover as many molecules in space as possible and to find the most important molecules for life: amino acids, DNA and RNA! As aspiring astronomers and astrobiologists, you will explore how these molecules are detected on Earth and in space. The `Search for Life’ is a pretty big task considering the size of the Universe. By learning how to find evidence of life forming molecules you will be able to provide conclusions that will shape policy regarding space missions, funding and technology development during your lifetime.

  9. Improved galvanic replacement growth of Ag microstructures on Cu micro-grid for enhanced SERS detection of organic molecules.

    Science.gov (United States)

    Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

    2016-04-01

    Galvanic growth of Ag nano/micro-structures on Cu micro-grid was systematically studied for surface-enhanced Raman scattering (SERS) applications. Detailed characterizations via FE-SEM and HR-TEM showed that processing parameters, (reaction time, Ag(+) concentration, and PVP addition) all substantially affect thermodynamics/kinetics of the replacement reaction to yield substrates of significantly different microstructures/homogeneities and thus varied SERS performances (sensitivity, enhancement factor, and reproducibility) of the Ag substrates in the detection of R6G analyte. PVP as an additive was shown to notably alter nucleation/growth behaviors of the Ag crystals and promote the deposition of dense and uniform Ag films of nearly monodisperse polyhedrons/nanoplates through suppressing dendrites crystallization. Under optimized synthesis (50mM of Ag(+), 30s of reaction, and 700 wt.% of PVP), Ag substrates exhibiting a high Raman signal enhancement factor of ~1.1 × 10(6) and a low relative standard deviation of ~0.13 in the repeated detection of 10 μM R6G were obtained. The facile deposition and excellent performance reported in this work may allow the Ag microstructures to find wider SERS applications. Moreover, growth mechanisms of the different Ag nano/micro-structures were discussed based on extensive FE-SEM and HR-TEM analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Event-specific qualitative and quantitative detection of five genetically modified rice events using a single standard reference molecule.

    Science.gov (United States)

    Kim, Jae-Hwan; Park, Saet-Byul; Roh, Hyo-Jeong; Shin, Min-Ki; Moon, Gui-Im; Hong, Jin-Hwan; Kim, Hae-Yeong

    2017-07-01

    One novel standard reference plasmid, namely pUC-RICE5, was constructed as a positive control and calibrator for event-specific qualitative and quantitative detection of genetically modified (GM) rice (Bt63, Kemingdao1, Kefeng6, Kefeng8, and LLRice62). pUC-RICE5 contained fragments of a rice-specific endogenous reference gene (sucrose phosphate synthase) as well as the five GM rice events. An existing qualitative PCR assay approach was modified using pUC-RICE5 to create a quantitative method with limits of detection correlating to approximately 1-10 copies of rice haploid genomes. In this quantitative PCR assay, the square regression coefficients ranged from 0.993 to 1.000. The standard deviation and relative standard deviation values for repeatability ranged from 0.02 to 0.22 and 0.10% to 0.67%, respectively. The Ministry of Food and Drug Safety (Korea) validated the method and the results suggest it could be used routinely to identify five GM rice events. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Progress in Fire Detection and Suppression Technology for Future Space Missions

    Science.gov (United States)

    Friedman, Robert; Urban, David L.

    2000-01-01

    Fire intervention technology (detection and suppression) is a critical part of the strategy of spacecraft fire safety. This paper reviews the status, trends, and issues in fire intervention, particularly the technology applied to the protection of the International Space Station and future missions beyond Earth orbit. An important contribution to improvements in spacecraft fire safety is the understanding of the behavior of fires in the non-convective (microgravity) environment of Earth-orbiting and planetary-transit spacecraft. A key finding is the strong influence of ventilation flow on flame characteristics, flammability limits and flame suppression in microgravity. Knowledge of these flow effects will aid the development of effective processes for fire response and technology for fire suppression.

  12. Analysis of Space Shuttle Ground Support System Fault Detection, Isolation, and Recovery Processes and Resources

    Science.gov (United States)

    Gross, Anthony R.; Gerald-Yamasaki, Michael; Trent, Robert P.

    2009-01-01

    As part of the FDIR (Fault Detection, Isolation, and Recovery) Project for the Constellation Program, a task was designed within the context of the Constellation Program FDIR project called the Legacy Benchmarking Task to document as accurately as possible the FDIR processes and resources that were used by the Space Shuttle ground support equipment (GSE) during the Shuttle flight program. These results served as a comparison with results obtained from the new FDIR capability. The task team assessed Shuttle and EELV (Evolved Expendable Launch Vehicle) historical data for GSE-related launch delays to identify expected benefits and impact. This analysis included a study of complex fault isolation situations that required a lengthy troubleshooting process. Specifically, four elements of that system were considered: LH2 (liquid hydrogen), LO2 (liquid oxygen), hydraulic test, and ground special power.

  13. The evaluation of phasemeter prototype performance for the space gravitational waves detection.

    Science.gov (United States)

    Liu, He-Shan; Dong, Yu-Hui; Li, Yu-Qiong; Luo, Zi-Ren; Jin, Gang

    2014-02-01

    Heterodyne laser interferometry is considered as the most promising readout scheme for future space gravitational wave detection missions, in which the gravitational wave signals disguise as small phase variances within the heterodyne beat note. This makes the phasemeter, which extracts the phase information from the beat note, the key device to this system. In this paper, a prototype of phasemeter based on digital phase-locked loop technology is developed, and the major noise sources which may contribute to the noise spectra density are analyzed in detail. Two experiments are also carried out to evaluate the performance of the phasemeter prototype. The results show that the sensitivity is achieved 2π μrad/√Hz in the frequency range of 0.04 Hz-10 Hz. Due to the effect of thermal drift, the noise obviously increases with the frequencies down to 0.1 mHz.

  14. Detection of gamma-ray bursts with the ECLAIRs instrument onboard the space mission SVOM

    International Nuclear Information System (INIS)

    Antier-Farfar, Sarah

    2016-01-01

    Discovered in the early 1970's, gamma-ray bursts (GRBs) are amazing cosmic phenomena appearing randomly on the sky and releasing large amounts of energy mainly through gamma-ray emission. Although their origin is still under debate, they are believed to be produced by some of the most violent explosions in the Universe leading to the formation of stellar black-holes. GRBs are detected by their prompt emission, an intense short burst of gamma-rays (from a few milliseconds to few minutes), and are followed by a lived-afterglow emission observed on longer timescales from the X-ray to the radio domain. My thesis participates to the development of the SVOM mission, which a Chinese-French mission to be launched in 2021, devoted to the study of GRBs and involving space and ground instruments. My work is focussed on the main instrument ECLAIRs, a hard X-ray coded mask imaging camera, in charge of the near real-time detection and localization of the prompt emission of GRBs. During my thesis, I studied the scientific performances of ECLAIRs and in particular the number of GRBs expected to be detected by ECLAIRs and their characteristics. For this purpose, I performed simulations using the prototypes of the embedded trigger algorithms combined with the model of the ECLAIRs instrument. The input data of the simulations include a background model and a synthetic population of gamma-ray bursts generated from existing catalogs (CGRO, HETE-2, Fermi and Swift). As a result, I estimated precisely the ECLAIRs detection efficiency of the algorithms and I predicted the number of GRBs to be detected by ECLAIRs: 40 to 70 GRBs per year. Moreover, the study highlighted that ECLAIRs will be particularly sensitive to the X-ray rich GRB population. My thesis provided additional studies about the localization performance, the rate of false alarm and the characteristics of the triggers of the algorithms. Finally, I also proposed two new methods for the detection of GRBs.The preliminary

  15. Polymerase-free measurement of microRNA-122 with single base specificity using single molecule arrays: Detection of drug-induced liver injury.

    Directory of Open Access Journals (Sweden)

    David M Rissin

    Full Text Available We have developed a single probe method for detecting microRNA from human serum using single molecule arrays, with sequence specificity down to a single base, and without the use of amplification by polymerases. An abasic peptide nucleic acid (PNA probe-containing a reactive amine instead of a nucleotide at a specific position in the sequence-for detecting a microRNA was conjugated to superparamagnetic beads. These beads were incubated with a sample containing microRNA, a biotinylated reactive nucleobase-containing an aldehyde group-that was complementary to the missing base in the probe sequence, and a reducing agent. When a target molecule with an exact match in sequence hybridized to the capture probe, the reactive nucleobase was covalently attached to the backbone of the probe by a dynamic covalent chemical reaction. Single molecules of the biotin-labeled probe were then labeled with streptavidin-β-galactosidase (SβG, the beads were resuspended in a fluorogenic enzyme substrate, loaded into an array of femtoliter wells, and sealed with oil. The array was imaged fluorescently to determine which beads were associated with single enzymes, and the average number of enzymes per bead was determined. The assay had a limit of detection of 500 fM, approximately 500 times more sensitive than a corresponding analog bead-based assay, with target specificity down to a single base mis-match. This assay was used to measure microRNA-122 (miR-122-an established biomarker of liver toxicity-extracted from the serum of patients who had acute liver injury due to acetaminophen, and control healthy patients. All patients with liver injury had higher levels of miR-122 in their serum compared to controls, and the concentrations measured correlated well with those determined using RT-qPCR. This approach allows rapid quantification of circulating microRNA with single-based specificity and a limit of quantification suitable for clinical use.

  16. Detection of low-energy antinuclei in space using an active-target particle detector

    Energy Technology Data Exchange (ETDEWEB)

    Poeschl, Thomas; Greenwald, Daniel; Konorov, Igor; Paul, Stephan [Physics Department E18, Technische Universitaet Muenchen (Germany); Losekamm, Martin [Physics Department E18, Technische Universitaet Muenchen (Germany); Institute of Astronautics, Technische Universitaet Muenchen (Germany)

    2015-07-01

    Measuring antimatter in space excellently probes various astrophysical processes. The abundances and energy spectra of antiparticles reveal a lot about the creation and propagation of cosmic-ray particles in the universe. Abnormalities in their spectra can reveal exotic sources or inaccuracies in our understanding of the involved processes. The measurement of antiprotons and the search for antideuterons and antihelium are optimal at low kinetic energies since background from high-energy cosmic-ray collisions is low. For this reason, we are developing an active-target particle detector capable of detecting ions and anti-ions in the energy range of 30-100 MeV per nucleon. The detector consists of 900 scintillating fibers coupled to silicon photomultipliers and is designed to operate on nanosatellites. The primary application of the detector will be the Antiproton Flux in Space (AFIS) mission, whose goal is the measurement of geomagnetically trapped antiprotons inside Earth's inner radiation belt. In this talk, we explain our particle identification technique and present results from first in-beam measurements with a prototype.

  17. Detecting kinematic boundary surfaces in phase space and particle mass measurements in SUSY-like events

    CERN Document Server

    Debnath, Dipsikha; Kilic, Can; Kim, Doojin; Matchev, Konstantin T.; Yang, Yuan-Pao

    2017-06-19

    We critically examine the classic endpoint method for particle mass determination, focusing on difficult corners of parameter space, where some of the measurements are not independent, while others are adversely affected by the experimental resolution. In such scenarios, mass differences can be measured relatively well, but the overall mass scale remains poorly constrained. Using the example of the standard SUSY decay chain $\\tilde q\\to \\tilde\\chi^0_2\\to \\tilde \\ell \\to \\tilde \\chi^0_1$, we demonstrate that sensitivity to the remaining mass scale parameter can be recovered by measuring the two-dimensional kinematical boundary in the relevant three-dimensional phase space of invariant masses squared. We develop an algorithm for detecting this boundary, which uses the geometric properties of the Voronoi tessellation of the data, and in particular, the relative standard deviation (RSD) of the volumes of the neighbors for each Voronoi cell in the tessellation. We propose a new observable, $\\bar\\Sigma$, which is ...

  18. Direct Generation and Detection of Quantum Correlated Photons with 3.2 um Wavelength Spacing.

    Science.gov (United States)

    Sua, Yong Meng; Fan, Heng; Shahverdi, Amin; Chen, Jia-Yang; Huang, Yu-Ping

    2017-12-13

    Quantum correlated, highly non-degenerate photons can be used to synthesize disparate quantum nodes and link quantum processing over incompatible wavelengths, thereby constructing heterogeneous quantum systems for otherwise unattainable superior performance. Existing techniques for correlated photons have been concentrated in the visible and near-IR domains, with the photon pairs residing within one micron. Here, we demonstrate direct generation and detection of high-purity photon pairs at room temperature with 3.2 um wavelength spacing, one at 780 nm to match the rubidium D2 line, and the other at 3950 nm that falls in a transparent, low-scattering optical window for free space applications. The pairs are created via spontaneous parametric downconversion in a lithium niobate waveguide with specially designed geometry and periodic poling. The 780 nm photons are measured with a silicon avalanche photodiode, and the 3950 nm photons are measured with an upconversion photon detector using a similar waveguide, which attains 34% internal conversion efficiency. Quantum correlation measurement yields a high coincidence-to-accidental ratio of 54, which indicates the strong correlation with the extremely non-degenerate photon pairs. Our system bridges existing quantum technology to the challenging mid-IR regime, where unprecedented applications are expected in quantum metrology and sensing, quantum communications, medical diagnostics, and so on.

  19. Detecting kinematic boundary surfaces in phase space: particle mass measurements in SUSY-like events

    CERN Document Server

    Debnath, Dipsikha; Kilic, Can; Kim, Doojin; Matchev, Konstantin T.; Yang, Yuan-Pao

    2017-06-19

    We critically examine the classic endpoint method for particle mass determination, focusing on difficult corners of parameter space, where some of the measurements are not independent, while others are adversely affected by the experimental resolution. In such scenarios, mass differences can be measured relatively well, but the overall mass scale remains poorly constrained. Using the example of the standard SUSY decay chain $\\tilde q\\to \\tilde\\chi^0_2\\to \\tilde \\ell \\to \\tilde \\chi^0_1$, we demonstrate that sensitivity to the remaining mass scale parameter can be recovered by measuring the two-dimensional kinematical boundary in the relevant three-dimensional phase space of invariant masses squared. We develop an algorithm for detecting this boundary, which uses the geometric properties of the Voronoi tessellation of the data, and in particular, the relative standard deviation (RSD) of the volumes of the neighbors for each Voronoi cell in the tessellation. We propose a new observable, $\\bar\\Sigma$, which is t...

  20. Upper ankle joint space detection on low contrast intraoperative fluoroscopic C-arm projections

    Science.gov (United States)

    Thomas, Sarina; Schnetzke, Marc; Brehler, Michael; Swartman, Benedict; Vetter, Sven; Franke, Jochen; Grützner, Paul A.; Meinzer, Hans-Peter; Nolden, Marco

    2017-03-01

    Intraoperative mobile C-arm fluoroscopy is widely used for interventional verification in trauma surgery, high flexibility combined with low cost being the main advantages of the method. However, the lack of global device-to- patient orientation is challenging, when comparing the acquired data to other intrapatient datasets. In upper ankle joint fracture reduction accompanied with an unstable syndesmosis, a comparison to the unfractured contralateral site is helpful for verification of the reduction result. To reduce dose and operation time, our approach aims at the comparison of single projections of the unfractured ankle with volumetric images of the reduced fracture. For precise assessment, a pre-alignment of both datasets is a crucial step. We propose a contour extraction pipeline to estimate the joint space location for a prealignment of fluoroscopic C-arm projections containing the upper ankle joint. A quadtree-based hierarchical variance comparison extracts potential feature points and a Hough transform is applied to identify bone shaft lines together with the tibiotalar joint space. By using this information we can define the coarse orientation of the projections independent from the ankle pose during acquisition in order to align those images to the volume of the fractured ankle. The proposed method was evaluated on thirteen cadaveric datasets consisting of 100 projections each with manually adjusted image planes by three trauma surgeons. The results show that the method can be used to detect the joint space orientation. The correlation between angle deviation and anatomical projection direction gives valuable input on the acquisition direction for future clinical experiments.

  1. N-doped graphene: an alternative carbon-based matrix for highly efficient detection of small molecules by negative ion MALDI-TOF MS.

    Science.gov (United States)

    Min, Qianhao; Zhang, Xiaoxia; Chen, Xueqin; Li, Siyuan; Zhu, Jun-Jie

    2014-09-16

    Gas-phase N-doped graphene (gNG) was synthesized by a modified thermal annealing method using gaseous melamine as nitrogen source and then for the first time applied as a matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for small molecule analysis. Unlike the complicated adducts produced in positive ion mode, MS spectra obtained on gNG matrix in negative ion mode was only featured by deprotonated molecule ion peaks without matrix interference. By the gNG assisted desorption/ionization (D/I) process, some applications were carried out on a wide range of low-molecular weight (MW) analytes including amino acids, fatty acids, peptides, anabolic androgenic steroids as well as anticancer drugs, with an extraordinary laser desorption/ionization (LDI) efficiency over traditional α-cyano-4-hydroxycinnamic acid (CHCA) and other carbon-based materials in the negative ion detection mode. By comparison of a series of graphene-based matrixes, two main factors of matrix gNG were unveiled to play a decisive role in assisting negative ion D/I process: a well-ordered π-conjugated system for laser absorption and energy transfer; pyridinic-doped nitrogen species functioning as deprotonation sites for proton capture on negative ionization. The good salt tolerance and high sensitivity allowed further therapeutic monitoring of anticancer drug nilotinib in the spiked human serum, a real case of biology. Signal response was definitely obtained between 1 mM and 1 μM, meeting the demand of assessing drug level in the patient serum. This work creates a new application branch for nitrogen-doped graphene and provides an alternative solution for small molecule analysis.

  2. Failure to detect variant (CRM+) plasma thromboplastin antecedent (factor XI) molecules in hereditary plasma thromboplastin antecedent deficiency: a study of 125 patients of several ethnic backgrounds.

    Science.gov (United States)

    Saito, H; Ratnoff, O D; Bouma, B N; Seligsohn, U

    1985-12-01

    Plasma samples of 125 patients from 80 kindreds with hereditary plasma thromboplastin antecedent (PTA, factor XI) deficiency were tested by factor XI radioimmunoassay (RIA) and electroimmunoassay (EIA) in an attempt to detect variant molecules. Ninety-six patients (70 kindreds) were Jewish, and 29 (10 kindreds) were of other ethnic backgrounds, namely, Japanese, black American, Korean, Arab, Indian, and English. Seventy-eight patients were homozygotes, and 47 were heterozygotes. Both non-Jewish homozygotes and heterozygotes had lower factor XI activity than respective Jewish subjects. Twenty-eight homozygotes whose factor XI clotting activities (XI:C) were 1.5% to 13% had factor XI-related antigen (XI:RAG) levels less than 10% by EIA. In 72 homozygotes, including 22 patients who were also tested with EIA, XI:C was 2.9% +/- 3.0% (mean +/- SD) and XI:RAG tested by RIA, 2.9% +/- 3.0%. In 47 heterozygotes, XI:C and XI:RAG tested by RIA were 51.9% +/- 16.6% and 51.0% +/- 16.2%, respectively. Similar results were obtained when only unrelated patients (62 homozygotes and 27 heterozygotes) were analyzed. There was a highly significant correlation between XI:C and XI:RAG (RIA) in 38 homozygotes and 47 heterozygotes (r = 0.94, n = 85, P less than 0.001). Thus, we failed to identify functionally abnormal factor XI molecules (CRM+ variant) in these patients with hereditary factor XI deficiency.

  3. Highly Efficient Electronic Sensitization of Non-oxidized Graphene Flakes on Controlled Pore-loaded WO3 Nanofibers for Selective Detection of H2S Molecules

    Science.gov (United States)

    Choi, Seon–Jin; Choi, Chanyong; Kim, Sang-Joon; Cho, Hee-Jin; Hakim, Meggie; Jeon, Seokwoo; Kim, Il–Doo

    2015-01-01

    Tailoring of semiconducting metal oxide nanostructures, which possess controlled pore size and concentration, is of great value to accurately detect various volatile organic compounds in exhaled breath, which act as potential biomarkers for many health conditions. In this work, we have developed a very simple and robust route for controlling both the size and distribution of spherical pores in electrospun WO3 nanofibers (NFs) via a sacrificial templating route using polystyrene colloids with different diameters (200 nm and 500 nm). A tentacle-like structure with randomly distributed pores on the surface of electrospun WO3 NFs were achieved, which exhibited improved surface area as well as porosity. Porous WO3 NFs with enhanced surface area exhibited high gas response (Rair/Rgas = 43.1 at 5 ppm) towards small and light H2S molecules. In contrast, porous WO3 NFs with maximized pore diameter showed a high response (Rair/Rgas = 2.8 at 5 ppm) towards large and heavy acetone molecules. Further enhanced sensing performance (Rair/Rgas = 65.6 at 5 ppm H2S) was achieved by functionalizing porous WO3 NFs with 0.1 wt% non-oxidized graphene (NOGR) flakes by forming a Schottky barrier (ΔΦ = 0.11) at the junction between the WO3 NFs (Φ = 4.56 eV) and NOGR flakes (Φ = 4.67 eV), which showed high potential for the diagnosis of halitosis.

  4. The microbe capture experiment in space: Fluorescence microscopic detection of microbes captured by aerogel

    Science.gov (United States)

    Sugino, Tomohiro; Yokobori, Shin-Ichi; Yang, Yinjie; Kawaguchi, Yuko; Okudaira, Kyoko; Tabata, Makoto; Kawai, Hideyuki; Hasegawa, Sunao; Yamagishi, Akihiko

    Microbes have been collected at the altitude up to about 70 km in the sampling experiment done by several groups[1]. We have also collected high altitude microbes, by using an airplane and balloons[2][3][4][5]. We collected new deinococcal strain (Deinococcus aetherius and Deinococ-cus aerius) and several strains of spore-forming bacilli from stratosphere[2][4][5]. However, microbe sampling in space has never been reported. On the other hand, "Panspermia" hy-pothesis, where terrestrial life is originated from outside of Earth, has been proposed[6][7][8][9]. Recent report suggesting existence of the possible microbe fossils in the meteorite of Mars origin opened the serious debate on the possibility of migration of life embedded in meteorites (and cosmic dusts)[10][11]. If we were able to find terrestrial microbes in space, it would suggest that the terrestrial life can travel between astronomical bodies. We proposed a mission "Tanpopo: Astrobiology Exposure and Micrometeoroid Capture Experiments" to examine possible inter-planetary migration of microbes, organic compounds and meteoroids on Japan Experimental Module of the International Space Station (ISS)[12]. Two of six sub themes in this mission are directly related to interplanetary migration of microbes. One is the direct capturing experi-ment of microbes (probably within the particles such as clay) in space by the exposed ultra-low density aerogel. Another is the exposure experiment to examine survivability of the microbes in harsh space environment. They will tell us the possibility of interplanetary migration of microbes (life) from Earth to outside of Earth (or vise versa). In this report, we will report whether aerogel that have been used for the collection of space debris and cosmic dusts can be used for microbe sampling in space. We will discuss how captured particles by aerogel can be detected with DNA-specific fluorescent dye, and how to distinguish microbes from other mate-rials (i.e. aerogel and

  5. A Selective Assay to Detect Chitin and Biologically Active Nano-Machineries for Chitin-Biosynthesis with Their Intrinsic Chitin-Synthase Molecules

    Directory of Open Access Journals (Sweden)

    Hildgund Schrempf

    2010-09-01

    Full Text Available A new assay system for chitin has been developed. It comprises the chitin-binding protein ChbB in fusion with a His-tag as well as with a Strep-tag, the latter of which was chemically coupled to horseradish peroxidase. With the resulting complex, minimal quantities of chitin are photometrically detectable. In addition, the assay allows rapid scoring of the activity of chitin-synthases. As a result, a refined procedure for the rapid purification of yeast chitosomes (nano-machineries for chitin biosynthesis has been established. Immuno-electronmicroscopical studies of purified chitosomes, gained from a yeast strain carrying a chitin-synthase gene fused to that for GFP (green-fluorescence protein, has led to the in situ localization of chitin-synthase-GFP molecules within chitosomes.

  6. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 4. Molecule Matters – van der Waals Molecules - History and Some Perspectives on Intermolecular Forces ... Author Affiliations. E Arunan1. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  7. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 4. Molecule Matters – van der Waals Molecules - History and Some Perspectives on Intermolecular Forces. E Arunan. Feature Article Volume 14 Issue 4 April 2009 pp 346-356 ...

  8. Role of near ultraviolet wavelength measurements in the detection and retrieval of absorbing aerosols from space

    Science.gov (United States)

    Mukai, Sonoyo; Fujito, Toshiyuki; Nakata, Makiko; Sano, Itaru

    2017-10-01

    Aerosol remote sensing by ultraviolet (UV) wavelength is established by a Total Ozone Mapping Spectrometer (TOMS) mounted on the long-life satellite Nimbus-7 and continues to make observations using Ozone monitoring instrument (OMI) located on the Aura satellite. For example, TOMS demonstrated that UV radiation (0.331 and 0.360 μm) could easily detect absorbing particles such as mineral dust or smoke aerosols. TOMS-AI (absorbing aerosol index) has been used to identify the absorbing aerosols from space. For an upcoming mission, JAXA/GCOM-C will have the polarization sensor SGLI boarded in December 2017. The SGLI has multi (19)-channels including near UV (0.380 μm) and violet (0.412 μm) wavelengths. This work intends to examine the role of near UV data in the detection of absorbing aerosols similar to TOMS-AI played. In practice, the measurements by GLI mounted on the short Japanese mission JAXA/ADEOS-2, whose data archive period was just 8 months from April to October in 2003, are available for simulation of SGLI data because ADEOS-2/GLI installed near UV and violet channels. First of all, the ratio of data at 0.412 μm to that at 0.380 μm is examined as an indicator to detect absorbing aerosols on a global scale during ADEOS-2 era. It is noted that our research group has developed an efficient algorithm for aerosol retrieval in hazy episodes (dense concentrations of atmospheric aerosols). It can be said that at least this work is an attempt to grasp the biomass burning plumes from the satellite.

  9. Wireless and simultaneous detections of multiple bio-molecules in a single sensor using Love wave biosensor.

    Science.gov (United States)

    Oh, Haekwan; Fu, Chen; Kim, Kunnyun; Lee, Keekeun

    2014-11-17

    A Love wave-based biosensor with a 440 MHz center frequency was developed for the simultaneous detection of two different analytes of Cartilage Oligomeric Matrix Protein (COMP) and rabbit immunoglobulin G (IgG) in a single sensor. The developed biosensor consists of one-port surface acoustic wave (SAW) reflective delay lines on a 41° YX LiNbO3 piezoelectric substrate, a poly(methyl methacrylate) (PMMA) waveguide layer, and two different sensitive films. The Love wave biosensor was wirelessly characterized using two antennas and a network analyzer. The binding of the analytes to the sensitive layers induced a large change in the time positions of the original reflection peaks mainly due to the mass loading effect. The assessed time shifts in the reflection peaks were matched well with the predicted values from coupling of mode (COM) modeling. The sensitivities evaluated from the sensitive films were ~15 deg/µg/mL for the rabbit IgG and ~1.8 deg/ng/mL for COMP.

  10. Wireless and Simultaneous Detections of Multiple Bio-Molecules in a Single Sensor Using Love Wave Biosensor

    Directory of Open Access Journals (Sweden)

    Haekwan Oh

    2014-11-01

    Full Text Available A Love wave-based biosensor with a 440 MHz center frequency was developed for the simultaneous detection of two different analytes of Cartilage Oligomeric Matrix Protein (COMP and rabbit immunoglobulin G (IgG in a single sensor. The developed biosensor consists of one-port surface acoustic wave (SAW reflective delay lines on a 41° YX LiNbO3 piezoelectric substrate, a poly(methyl methacrylate (PMMA waveguide layer, and two different sensitive films. The Love wave biosensor was wirelessly characterized using two antennas and a network analyzer. The binding of the analytes to the sensitive layers induced a large change in the time positions of the original reflection peaks mainly due to the mass loading effect. The assessed time shifts in the reflection peaks were matched well with the predicted values from coupling of mode (COM modeling. The sensitivities evaluated from the sensitive films were ~15 deg/µg/mL for the rabbit IgG and ~1.8 deg/ng/mL for COMP.

  11. Influence of the input database in detecting fire space-time clusters

    Science.gov (United States)

    Pereira, Mário; Costa, Ricardo; Tonini, Marj; Vega Orozco, Carmen; Parente, Joana

    2015-04-01

    Fire incidence variability is influenced by local environmental variables such as topography, land use, vegetation and weather conditions. These induce a cluster pattern of the fire events distribution. The space-time permutation scan statistics (STPSS) method developed by Kulldorff et al. (2005) and implemented in the SaTScanTM software (http://www.satscan.org/) proves to be able to detect space-time clusters in many different fields, even when using incomplete and/or inaccurate input data. Nevertheless, the dependence of the STPSS method on the different characteristics of different datasets describing the same environmental phenomenon has not been studied yet. In this sense, the objective of this study is to assess the robustness of the STPSS for detecting real clusters using different input datasets and to justify the obtained results. This study takes advantage of the existence of two very different official fire datasets currently available for Portugal, both provided by the Institute for the Conservation of Nature and Forests. The first one is the aggregated Portuguese Rural Fire Database PRFD (Pereira et al., 2011), which is based on ground measurements and provides detailed information about the ignition and extinction date/time and the area burnt by each fire in forest, scrubs and agricultural areas. However, in the PRFD, the fire location of each fire is indicated by the name of smallest administrative unit (the parish) where the ignition occurred. Consequently, since the application of the STPSS requires the geographic coordinates of the events, the centroid of the parishes was considered. The second fire dataset is the national mapping burnt areas (NMBA), which is based on satellite measurements and delivered in shape file format. The NMBA provides a detailed spatial information (shape and size of each fire) but the temporal information is restricted to the year of occurrence. Besides these differences, the two datasets cover different periods, they

  12. Infrared laser induced population transfer and parity selection in {sup 14}NH{sub 3}: A proof of principle experiment towards detecting parity violation in chiral molecules

    Energy Technology Data Exchange (ETDEWEB)

    Dietiker, P.; Miloglyadov, E.; Quack, M., E-mail: Martin@Quack.ch; Schneider, A.; Seyfang, G. [Physical Chemistry, ETH Zürich, CH-8093 Zürich (Switzerland)

    2015-12-28

    We have set up an experiment for the efficient population transfer by a sequential two photon—absorption and stimulated emission—process in a molecular beam to prepare quantum states of well defined parity and their subsequent sensitive detection. This provides a proof of principle for an experiment which would allow for parity selection and measurement of the time evolution of parity in chiral molecules, resulting in a measurement of the parity violating energy difference Δ{sub pv}E between enantiomers of chiral molecules. Here, we present first results on a simple achiral molecule demonstrating efficient population transfer (about 80% on the average for each step) and unperturbed persistence of a selected excited parity level over flight times of about 1.3 ms in the beam. In agreement with model calculations with and without including nuclear hyperfine structure, efficient population transfer can be achieved by a rather simple implementation of the rapid adiabatic passage method of Reuss and coworkers and considering also the stimulated Raman adiabatic passage technique of Bergmann and coworkers as an alternative. The preparation step uses two powerful single mode continuous wave optical parametric oscillators of high frequency stability and accuracy. The detection uses a sensitive resonantly enhanced multiphoton ionization method after free flight lengths of up to 0.8 m in the molecular beam. Using this technique, we were able to also resolve the nuclear hyperfine structure in the rovibrational levels of the ν{sub 1} and ν{sub 3} fundamentals as well as the 2ν{sub 4} overtone of {sup 14}NH{sub 3}, for which no previous data with hyperfine resolution were available. We present our new results on the quadrupole coupling constants for the ν{sub 1}, ν{sub 3}, and 2ν{sub 4} levels in the context of previously known data for ν{sub 2} and its overtone, as well as ν{sub 4}, and the ground state. Thus, now, {sup 14}N quadrupole coupling constants for all

  13. Interstellar molecules: guides for new chemistry.

    Science.gov (United States)

    Mandal, Swadhin K; Roesky, Herbert W

    2010-09-07

    Interstellar space is among the most remarkable chemical laboratories in the universe. The existence of many unstable species with low-valent main group elements in the interstellar medium inspired us to investigate the feasibility of laboratory synthesis of such unstable molecules. Particularly the lighter Group 14 element carbon plays a very important role in space astrochemistry. Low-valent carbon as well as silicon were detected in the interstellar environment. This article describes our recent efforts in developing amazing chemistry of heavier low-valent Group 14 elements. This study unravels that the disproportionation pathway of the low-valent Group 14 elements can be arrested by using a sterically protected ligand, then one can artificially generate the situation observed in the interstellar surrounding where the chance of disproportionation is very low as the molecules are extremely dilute.

  14. Detection of vascular cell adhesion molecule-1 expression with USPIO-enhanced molecular MRI in a mouse model of cerebral ischemia

    International Nuclear Information System (INIS)

    Frechou, M.; Beray-Berthat, V.; Plotkine, M.; Marchand-Leroux, C.; Margaill, I.; Raynaud, J.S.; Gombert, F.; Lancelot, E.; Ballet, S.; Robert, P.; Louin, G.; Meriaux, S.

    2013-01-01

    Vascular damage plays a critical role after stroke, leading notably to edema, hemorrhages and stroke recurrence. Tools to characterize the vascular lesion are thus a real medical need. In this context, the specific nano-particular contrast agent P03011, an USPIO (ultra-small superparamagnetic iron oxide) conjugated to a peptide that targets VCAM-1 (vascular cell adhesion molecule-1), was developed to detect this major component of the vascular inflammatory response. This study aimed to make the proof of concept of the capacity of this targeted USPIO to detect VCAM-1 with MRI after cerebral ischemia in mouse. The time course of VCAM-1 expression was first examined by immunohistochemistry in our model of cerebral ischemia-reperfusion. Secondly, P03011 or non-targeted USPIO P03007 were injected 5 h after ischemia (100 mmol iron kg -1 ; i.v.) and in vivo and ex vivo MRI were performed 24 h after ischemia onset. Double labeling immunofluorescence was then performed on brain slices in order to detect both USPIO and VCAM-1. VCAM-1 expression was significantly up-regulated 24 h after ischemia in our model. In animals receiving P03011, both in vivo and ex vivo MRI performed 24 h after ischemia onset showed hypointense foci which could correspond to iron particles. Histological analysis showed a co-localization of the targeted USPIO and VCAM-1. This study demonstrates that VCAM-1 detection is possible with the USPIO P03011 in a model of cerebral ischemia. This kind of contrast agent could be an interesting clinical tool to characterize ischemic lesions in terms of vascular damage. (authors)

  15. Implementation of a model based fault detection and diagnosis for actuation faults of the Space Shuttle main engine

    Science.gov (United States)

    Duyar, A.; Guo, T.-H.; Merrill, W.; Musgrave, J.

    1992-01-01

    In a previous study, Guo, Merrill and Duyar, 1990, reported a conceptual development of a fault detection and diagnosis system for actuation faults of the space shuttle main engine. This study, which is a continuation of the previous work, implements the developed fault detection and diagnosis scheme for the real time actuation fault diagnosis of the space shuttle main engine. The scheme will be used as an integral part of an intelligent control system demonstration experiment at NASA Lewis. The diagnosis system utilizes a model based method with real time identification and hypothesis testing for actuation, sensor, and performance degradation faults.

  16. Atkins' molecules

    CERN Document Server

    Atkins, Peters

    2003-01-01

    Originally published in 2003, this is the second edition of a title that was called 'the most beautiful chemistry book ever written'. In it, we see the molecules responsible for the experiences of our everyday life - including fabrics, drugs, plastics, explosives, detergents, fragrances, tastes, and sex. With engaging prose Peter Atkins gives a non-technical account of an incredible range of aspects of the world around us, showing unexpected connections, and giving an insight into how this amazing world can be understood in terms of the atoms and molecules from which it is built. The second edition includes dozens of extra molecules, graphical presentation, and an even more accessible and enthralling account of the molecules themselves.

  17. Interstellar Molecules

    Science.gov (United States)

    Solomon, Philip M.

    1973-01-01

    Radioastronomy reveals that clouds between the stars, once believed to consist of simple atoms, contain molecules as complex as seven atoms and may be the most massive objects in our Galaxy. (Author/DF)

  18. A scale space approach for unsupervised feature selection in mass spectra classification for ovarian cancer detection.

    Science.gov (United States)

    Ceccarelli, Michele; d'Acierno, Antonio; Facchiano, Angelo

    2009-10-15

    Mass spectrometry spectra, widely used in proteomics studies as a screening tool for protein profiling and to detect discriminatory signals, are high dimensional data. A large number of local maxima (a.k.a. peaks) have to be analyzed as part of computational pipelines aimed at the realization of efficient predictive and screening protocols. With this kind of data dimensions and samples size the risk of over-fitting and selection bias is pervasive. Therefore the development of bio-informatics methods based on unsupervised feature extraction can lead to general tools which can be applied to several fields of predictive proteomics. We propose a method for feature selection and extraction grounded on the theory of multi-scale spaces for high resolution spectra derived from analysis of serum. Then we use support vector machines for classification. In particular we use a database containing 216 samples spectra divided in 115 cancer and 91 control samples. The overall accuracy averaged over a large cross validation study is 98.18. The area under the ROC curve of the best selected model is 0.9962. We improved previous known results on the problem on the same data, with the advantage that the proposed method has an unsupervised feature selection phase. All the developed code, as MATLAB scripts, can be downloaded from http://medeaserver.isa.cnr.it/dacierno/spectracode.htm.

  19. Our Galactic Neighbor Hosts Complex Organic Molecules

    Science.gov (United States)

    Hensley, Kerry

    2018-03-01

    For the first time, data from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal the presence of methyl formate and dimethyl ether in a star-forming region outside our galaxy. This discovery has important implications for the formation and survival of complex organic compounds importantfor the formation of life in low-metallicity galaxies bothyoung and old.No Simple Picture of Complex Molecule FormationALMA, pictured here with the Magellanic Clouds above, has observed organic molecules in our Milky Way Galaxy and beyond. [ESO/C. Malin]Complex organic molecules (those with at least six atoms, one or more of which must be carbon) are the precursors to the building blocks of life. Knowing how and where complex organic molecules can form is a key part of understanding how life came to be on Earth and how it might arise elsewhere in the universe. From exoplanet atmospheres to interstellar space, complex organic molecules are ubiquitous in the Milky Way.In our galaxy, complex organic molecules are often found in the intense environments of hot cores clumps of dense molecular gas surrounding the sites of star formation. However, its not yet fully understood how the complex organic molecules found in hot cores come to be. One possibility is that the compounds condense onto cold dust grains long before the young stars begin heating their natal shrouds. Alternatively, they might assemble themselves from the hot, dense gas surrounding the blazing protostars.Composite infrared and optical image of the N 113 star-forming region in the LMC. The ALMA coverage is indicated by the gray line. Click to enlarge. [Sewio et al. 2018]Detecting Complexity, a Galaxy AwayUsing ALMA, a team of researchers led by Marta Sewio (NASA Goddard Space Flight Center) recently detected two complex organic molecules methyl formate and dimethyl ether for the first time in our neighboring galaxy, the Large Magellanic Cloud (LMC). Previous searches for organic molecules in the LMC detected

  20. Highly sensitive detection of mutations in CHO cell recombinant DNA using multi-parallel single molecule real-time DNA sequencing.

    Science.gov (United States)

    Cartwright, Joseph F; Anderson, Karin; Longworth, Joseph; Lobb, Philip; James, David C

    2018-02-10

    High-fidelity replication of biologic-encoding recombinant DNA sequences by engineered mammalian cell cultures is an essential pre-requisite for the development of stable cell lines for the production of biotherapeutics. However, immortalized mammalian cells characteristically exhibit an increased point mutation frequency compared to mammalian cells in vivo, both across their genomes and at specific loci (hotspots). Thus unforeseen mutations in recombinant DNA sequences can arise and be maintained within producer cell populations. These may affect both the stability of recombinant gene expression and give rise to protein sequence variants with variable bioactivity and immunogenicity. Rigorous quantitative assessment of recombinant DNA integrity should therefore form part of the cell line development process and be an essential quality assurance metric for instances where synthetic/multi-component assemblies are utilized to engineer mammalian cells, such as the assessment of recombinant DNA fidelity or the mutability of single-site integration target loci. Based on Pacific Biosciences (Menlo Park, CA) single molecule real-time (SMRT™) circular consensus sequencing (CCS) technology we developed a rDNA sequence analysis tool to process the multi-parallel sequencing of ∼40,000 single recombinant DNA molecules. After statistical filtering of raw sequencing data, we show that this analytical method is capable of detecting single point mutations in rDNA to a minimum single mutation frequency of 0.0042% (sequence. There was no discernable difference between the mutation frequencies of coding and non-coding DNA. The putative ratio of non-synonymous and synonymous changes within the open reading frames (ORFs) in the plasmid sequence indicates that natural selection does not impact upon the prevalence of these mutations. Here we have demonstrated the abundance of mutations that fall outside of the reported range of detection of next generation sequencing (NGS) and second

  1. Single molecules and nanotechnology

    CERN Document Server

    Vogel, Horst

    2007-01-01

    This book focuses on recent advances in the rapidly evolving field of single molecule research. These advances are of importance for the investigation of biopolymers and cellular biochemical reactions, and are essential to the development of quantitative biology. Written by leading experts in the field, the articles cover a broad range of topics, including: quantum photonics of organic dyes and inorganic nanoparticles their use in detecting properties of single molecules the monitoring of single molecule (enzymatic) reactions single protein (un)folding in nanometer-sized confined volumes the dynamics of molecular interactions in biological cells The book is written for advanced students and scientists who wish to survey the concepts, techniques and results of single molecule research and assess them for their own scientific activities.

  2. Combining local scaling and global methods to detect soil pore space

    Science.gov (United States)

    Martin-Sotoca, Juan Jose; Saa-Requejo, Antonio; Grau, Juan B.; Tarquis, Ana M.

    2017-04-01

    The characterization of the spatial distribution of soil pore structures is essential to obtain different parameters that will influence in several models related to water flow and/or microbial growth processes. The first step in pore structure characterization is obtaining soil images that best approximate reality. Over the last decade, major technological advances in X-ray computed tomography (CT) have allowed for the investigation and reconstruction of natural porous media architectures at very fine scales. The subsequent step is delimiting the pore structure (pore space) from the CT soil images applying a thresholding. Many times we could find CT-scan images that show low contrast at the solid-void interface that difficult this step. Different delimitation methods can result in different spatial distributions of pores influencing the parameters used in the models. Recently, new local segmentation method using local greyscale value (GV) concentration variabilities, based on fractal concepts, has been presented. This method creates singularity maps to measure the GV concentration at each point. The C-A method was combined with the singularity map approach (Singularity-CA method) to define local thresholds that can be applied to binarize CT images. Comparing this method with classical methods, such as Otsu and Maximum Entropy, we observed that more pores can be detected mainly due to its ability to amplify anomalous concentrations. However, it delineated many small pores that were incorrect. In this work, we present an improve version of Singularity-CA method that avoid this problem basically combining it with the global classical methods. References Martín-Sotoca, J.J., A. Saa-Requejo, J.B. Grau, A.M. Tarquis. New segmentation method based on fractal properties using singularity maps. Geoderma, 287, 40-53, 2017. Martín-Sotoca, J.J, A. Saa-Requejo, J.B. Grau, A.M. Tarquis. Local 3D segmentation of soil pore space based on fractal properties using singularity

  3. High Resolution Millimeter Wave Detection of Vertical Cracks in the Space Shuttle External Tank Spray-on-Foam Insulation (SOFI)

    Science.gov (United States)

    Kharkovsky, S.; Zoughi, R.; Hepburn, F.

    2007-03-01

    Space Shuttle Columbia's catastrophic failure, the separation of a piece of spray-on-foam insulation (SOFI) from the external tank (ET) in the Space Shuttle Discovery's flight in 2005 and crack detected in its ET foam prior to its successful launch in 2006 emphasize the need for effective nondestructive methods for inspecting the shuttle ET SOFI. Millimeter wave nondestructive testing methods have been considered as potential and effective inspection tools for evaluating the integrity of the SOFI. This paper presents recent results of an investigation for the purpose of detecting vertical cracks in SOFI panels using a focused millimeter wave (150 GHz) reflectometer. The presented images of the SOFI panels show the capability of this reflectometer for detecting tight vertical cracks (also as a function of crack opening dimension) in exposed SOFI panels and while covered by a piece of SOFI ramp simulating a more realistic and challenging situation.

  4. Reliability-aware iterative detection scheme (RAID) for distributed IDM space-time codes in relay systems

    Science.gov (United States)

    Lenkeit, Florian; Wübben, Dirk; Dekorsy, Armin

    2013-12-01

    In this article, distributed interleave-division multiplexing space-time codes (dIDM-STCs) are applied for multi-user two-hop decode-and-forward (DF) relay networks. In case of decoding errors at the relays which propagate to the destination, severe performance degradations can occur as the original detection scheme for common IDM-STCs does not take any reliability information about the first hop into account. Here, a novel reliability-aware iterative detection scheme (RAID) for dIDM-STCs is proposed. This new detection scheme takes the decoding reliability of the relays for each user into account for the detection at the destination. Performance evaluations show that the proposed RAID scheme clearly outperforms the original detection scheme and that in certain scenarios even a better performance than for adaptive relaying schemes can be achieved.

  5. MOLECULES IN {eta} CARINAE

    Energy Technology Data Exchange (ETDEWEB)

    Loinard, Laurent; Menten, Karl M.; Guesten, Rolf [Max-Planck Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Zapata, Luis A.; Rodriguez, Luis F. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 3-72, 58090 Morelia, Michoacan (Mexico)

    2012-04-10

    We report the detection toward {eta} Carinae of six new molecules, CO, CN, HCO{sup +}, HCN, HNC, and N{sub 2}H{sup +}, and of two of their less abundant isotopic counterparts, {sup 13}CO and H{sup 13}CN. The line profiles are moderately broad ({approx}100 km s{sup -1}), indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO{sup +} do not appear to be underabundant in {eta} Carinae. On the other hand, molecules containing nitrogen or the {sup 13}C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of {eta} Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.

  6. MOLECULES IN η CARINAE

    International Nuclear Information System (INIS)

    Loinard, Laurent; Menten, Karl M.; Güsten, Rolf; Zapata, Luis A.; Rodríguez, Luis F.

    2012-01-01

    We report the detection toward η Carinae of six new molecules, CO, CN, HCO + , HCN, HNC, and N 2 H + , and of two of their less abundant isotopic counterparts, 13 CO and H 13 CN. The line profiles are moderately broad (∼100 km s –1 ), indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO + do not appear to be underabundant in η Carinae. On the other hand, molecules containing nitrogen or the 13 C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of η Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.

  7. Adhesion molecules

    CERN Document Server

    Preedy, Victor R

    2016-01-01

    This book covers the structure and classification of adhesion molecules in relation to signaling pathways and gene expression. It discusses immunohistochemical localization, neutrophil migration, and junctional, functional, and inflammatory adhesion molecules in pathologies such as leukocyte decompression sickness and ischemia reperfusion injury. Highlighting the medical applications of current research, chapters cover diabetes, obesity, and metabolic syndrome; hypoxia; kidney disease; smoking, atrial fibrillation, and heart disease, the brain and dementia; and tumor proliferation. Finally, it looks at molecular imaging and bioinformatics, high-throughput technologies, and chemotherapy.

  8. a Prealiminary Study of Ship Detection from Uav Images Based on Color Space Conversion and Image Segmentation

    Science.gov (United States)

    Klimkowska, A. M.; Lee, I.

    2017-08-01

    Ship detection is an inherent process supporting tasks such as fishery management, ship search, marine traffic monitoring and control, and helps in the prevention of illegal activities. So far, sea and shore monitoring has been carried out by ship patrols and aircrafts along with sea vessel detection from data from space-borne platforms. Recently an increase interest in applying images delivered by UAV for marine application due to their advantages such as high spatial resolution, independence on time acquisition can be noticed. While investigating state of the art methods used for ship detection from different platforms using optical images, we found a significant problem with occurrence of a ship wake. This phenomena may prohibit correct detection of ship location and results in overestimating the ship size as the ship and its wake are often considered as being part of the same object in image or wakes are distinguished as a separate ship due to their possible similar brightness compared with sea vessel. In order to reduce the impact of ship wakes we investigated the behavior of images in different color spaces to provide data with little or almost no trace of ship wake. We took into consideration following color spaces: HSV, YCbCr, NTSC, XYZ and L*a*b and investigated each channel from new images. Finally we decided to use 2nd channel of L*a*b space where the ship wakes occurrence were significantly reduced. Object of interest were detected through the use of image segmentation. Applied method uses edge detection based on the gradient magnitude calculation. Afterwards several characteristics such as centroids, major and minor axis, size and orientation were calculated for later use to remove false positives and thus improve accuracy of the proposed method.

  9. A PREALIMINARY STUDY OF SHIP DETECTION FROM UAV IMAGES BASED ON COLOR SPACE CONVERSION AND IMAGE SEGMENTATION

    Directory of Open Access Journals (Sweden)

    A. M. Klimkowska

    2017-08-01

    Full Text Available Ship detection is an inherent process supporting tasks such as fishery management, ship search, marine traffic monitoring and control, and helps in the prevention of illegal activities. So far, sea and shore monitoring has been carried out by ship patrols and aircrafts along with sea vessel detection from data from space-borne platforms. Recently an increase interest in applying images delivered by UAV for marine application due to their advantages such as high spatial resolution, independence on time acquisition can be noticed. While investigating state of the art methods used for ship detection from different platforms using optical images, we found a significant problem with occurrence of a ship wake. This phenomena may prohibit correct detection of ship location and results in overestimating the ship size as the ship and its wake are often considered as being part of the same object in image or wakes are distinguished as a separate ship due to their possible similar brightness compared with sea vessel. In order to reduce the impact of ship wakes we investigated the behavior of images in different color spaces to provide data with little or almost no trace of ship wake. We took into consideration following color spaces: HSV, YCbCr, NTSC, XYZ and L*a*b and investigated each channel from new images. Finally we decided to use 2nd channel of L*a*b space where the ship wakes occurrence were significantly reduced. Object of interest were detected through the use of image segmentation. Applied method uses edge detection based on the gradient magnitude calculation. Afterwards several characteristics such as centroids, major and minor axis, size and orientation were calculated for later use to remove false positives and thus improve accuracy of the proposed method.

  10. DETECTABILITY OF FREE FLOATING PLANETS IN OPEN CLUSTERS WITH THE JAMES WEBB SPACE TELESCOPE

    International Nuclear Information System (INIS)

    Pacucci, Fabio; Ferrara, Andrea; D'Onghia, Elena

    2013-01-01

    Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate N-dot o (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρ * of the cluster: N-dot o =αρ ⋆ , with α = (23 ± 5) × 10 –6 pc 3 Myr –1 . For the Pleiades (M45), we predict that ∼26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ∼500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F ν (4.4 μm) ≈4 × 10 2  nJy, which would lead to a very clear detection (S/N ∼ 100) in only one hour of integration

  11. Detectability of Free Floating Planets in Open Clusters with the James Webb Space Telescope

    Science.gov (United States)

    Pacucci, Fabio; Ferrara, Andrea; D'Onghia, Elena

    2013-12-01

    Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate \\dot{N}_o (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρsstarf of the cluster: \\dot{N}_o = \\alpha \\rho _\\star, with α = (23 ± 5) × 10-6 pc3 Myr-1. For the Pleiades (M45), we predict that ~26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ~500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F ν (4.4 μm) ≈4 × 102 nJy, which would lead to a very clear detection (S/N ~ 100) in only one hour of integration.

  12. DETECTABILITY OF FREE FLOATING PLANETS IN OPEN CLUSTERS WITH THE JAMES WEBB SPACE TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Pacucci, Fabio; Ferrara, Andrea [Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy); D' Onghia, Elena [University of Wisconsin, 475 Charter St., Madison, WI 53706 (United States)

    2013-12-01

    Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate N-dot {sub o} (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρ{sub *} of the cluster: N-dot {sub o}=αρ{sub ⋆}, with α = (23 ± 5) × 10{sup –6} pc{sup 3} Myr{sup –1}. For the Pleiades (M45), we predict that ∼26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ∼500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F {sub ν} (4.4 μm) ≈4 × 10{sup 2} nJy, which would lead to a very clear detection (S/N ∼ 100) in only one hour of integration.

  13. Ultrahigh-sensitive detection of molecules produced in catalytic reactions by uni-atomic-composition bi-element clusters supported on solid substrate

    International Nuclear Information System (INIS)

    Yasumatsu, H; Fukui, N

    2013-01-01

    An apparatus has been developed for measuring catalytic activities of uni-atomic-composition bi-element clusters supported on a solid substrate. The cluster sample is prepared by irradiating a cluster-ion beam having the uni-atomic composition onto the substrate on a soft-landing condition in an ultra-high vacuum. The catalytic activity is measured by temperature-programmed desorption (TPD) mass analysis. Molecules at a density as low as 3 cm −3 have been detected with an ultrahigh-sensitive TPD mass spectrometer consisting of a cylindrical electron gun, a quadrupole mass filter and a micro-channel-plate ion-detector. The high reproducibility has been achieved by careful calibration of the TPD mass spectrometer. As a benchmark example, thermal oxidation of CO catalysed on Pt 30 disks supported on a silicon surface was studied. The CO 2 products have been successfully observed at the Pt 30 density as low as 3 × 10 12 clusters in a circular area of 8 mm in diameter at the ramping rate of the sample temperature as low as 0.3 K s −1 .

  14. Cryo-electron microscopy and single molecule fluorescent microscopy detect CD4 receptor induced HIV size expansion prior to cell entry

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Son [Deakin University, Victoria 3216 (Australia); CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Tabarin, Thibault [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Garvey, Megan; Pade, Corinna [Deakin University, Victoria 3216 (Australia); CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Rossy, Jérémie [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Monaghan, Paul; Hyatt, Alex [CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Böcking, Till [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Leis, Andrew [CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Gaus, Katharina, E-mail: k.gaus@unsw.edu.au [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Mak, Johnson, E-mail: j.mak@deakin.edu.au [Deakin University, Victoria 3216 (Australia); CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia)

    2015-12-15

    Viruses are often thought to have static structure, and they only remodel after the viruses have entered target cells. Here, we detected a size expansion of virus particles prior to viral entry using cryo-electron microscopy (cryo-EM) and single molecule fluorescence imaging. HIV expanded both under cell-free conditions with soluble receptor CD4 (sCD4) targeting the CD4 binding site on the HIV-1 envelope protein (Env) and when HIV binds to receptor on cellular membrane. We have shown that the HIV Env is needed to facilitate receptor induced virus size expansions, showing that the ‘lynchpin’ for size expansion is highly specific. We demonstrate that the size expansion required maturation of HIV and an internal capsid core with wild type stability, suggesting that different HIV compartments are linked and are involved in remodelling. Our work reveals a previously unknown event in HIV entry, and we propose that this pre-entry priming process enables HIV particles to facilitate the subsequent steps in infection. - Highlights: • Cell free viruses are able to receive external trigger that leads to apparent size expansion. • Virus envelope and CD4 receptor engagement is the lynchpin of virus size expansion. • Internal capsid organisation can influence receptor mediated virus size expansion. • Pre-existing virus-associated lipid membrane in cell free virus can accommodate the receptor mediated virus size expansion.

  15. Cryo-electron microscopy and single molecule fluorescent microscopy detect CD4 receptor induced HIV size expansion prior to cell entry

    International Nuclear Information System (INIS)

    Pham, Son; Tabarin, Thibault; Garvey, Megan; Pade, Corinna; Rossy, Jérémie; Monaghan, Paul; Hyatt, Alex; Böcking, Till; Leis, Andrew; Gaus, Katharina; Mak, Johnson

    2015-01-01

    Viruses are often thought to have static structure, and they only remodel after the viruses have entered target cells. Here, we detected a size expansion of virus particles prior to viral entry using cryo-electron microscopy (cryo-EM) and single molecule fluorescence imaging. HIV expanded both under cell-free conditions with soluble receptor CD4 (sCD4) targeting the CD4 binding site on the HIV-1 envelope protein (Env) and when HIV binds to receptor on cellular membrane. We have shown that the HIV Env is needed to facilitate receptor induced virus size expansions, showing that the ‘lynchpin’ for size expansion is highly specific. We demonstrate that the size expansion required maturation of HIV and an internal capsid core with wild type stability, suggesting that different HIV compartments are linked and are involved in remodelling. Our work reveals a previously unknown event in HIV entry, and we propose that this pre-entry priming process enables HIV particles to facilitate the subsequent steps in infection. - Highlights: • Cell free viruses are able to receive external trigger that leads to apparent size expansion. • Virus envelope and CD4 receptor engagement is the lynchpin of virus size expansion. • Internal capsid organisation can influence receptor mediated virus size expansion. • Pre-existing virus-associated lipid membrane in cell free virus can accommodate the receptor mediated virus size expansion.

  16. A storage ring for neutral molecules

    NARCIS (Netherlands)

    Crompvoets, F.M.H.

    2005-01-01

    Time-varying inhomogeneous electric fields can be used to manipulate the motion of neutral molecules in phase-space, i.e., position-momentum space, via their electric dipole moment. A theoretical background is given on the motion of the molecules in phase-space. As the forces exerted on the

  17. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Molecule Matters - Dinitrogen. A G Samuelson J Jabadurai. Volume 16 Issue 12 ... Author Affiliations. A G Samuelson1 J Jabadurai1. Department of Inroganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  18. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 13; Issue 5. Molecule Matters - N-Heterocyclic Carbenes - The Stable Form of R2 C: Anil J Elias. Feature Article Volume 13 Issue 5 May 2008 pp 456-467. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 9. Molecule Matters - A Chromium Compound with a Quintuple Bond. K C Kumara Swamy. Feature Article Volume 11 Issue 9 September 2006 pp 72-75. Fulltext. Click here to view fulltext PDF. Permanent link:

  20. Expiratory flow rate, breath hold and anatomic dead space influence electronic nose ability to detect lung cancer.

    Science.gov (United States)

    Bikov, Andras; Hernadi, Marton; Korosi, Beata Zita; Kunos, Laszlo; Zsamboki, Gabriella; Sutto, Zoltan; Tarnoki, Adam Domonkos; Tarnoki, David Laszlo; Losonczy, Gyorgy; Horvath, Ildiko

    2014-12-16

    Electronic noses are composites of nanosensor arrays. Numerous studies showed their potential to detect lung cancer from breath samples by analysing exhaled volatile compound pattern ("breathprint"). Expiratory flow rate, breath hold and inclusion of anatomic dead space may influence the exhaled levels of some volatile compounds; however it has not been fully addressed how these factors affect electronic nose data. Therefore, the aim of the study was to investigate these effects. 37 healthy subjects (44 ± 14 years) and 27 patients with lung cancer (60 ± 10 years) participated in the study. After deep inhalation through a volatile organic compound filter, subjects exhaled at two different flow rates (50 ml/sec and 75 ml/sec) into Teflon-coated bags. The effect of breath hold was analysed after 10 seconds of deep inhalation. We also studied the effect of anatomic dead space by excluding this fraction and comparing alveolar air to mixed (alveolar + anatomic dead space) air samples. Exhaled air samples were processed with Cyranose 320 electronic nose. Expiratory flow rate, breath hold and the inclusion of anatomic dead space significantly altered "breathprints" in healthy individuals (p 0.05). These factors also influenced the discrimination ability of the electronic nose to detect lung cancer significantly. We have shown that expiratory flow, breath hold and dead space influence exhaled volatile compound pattern assessed with electronic nose. These findings suggest critical methodological recommendations to standardise sample collections for electronic nose measurements.

  1. Cold guided beams of polar molecules

    International Nuclear Information System (INIS)

    Motsch, Michael

    2010-01-01

    spectroscopy of formaldehyde. First, ultraviolet absorption spectroscopy of the A 1 A 2 1 A 1 transition of formaldehyde is performed in a room-temperature gas to extract molecular constants. These findings are used to address single rotational states of guided molecules. Since the formaldehyde molecules dissociate upon ultraviolet excitation, the laser-frequency-dependent decrease in the number of guided molecules allows to extract the population of individual rotational states in the beam. With the source temperature set to 155 K, populations of rotational states exceeding 10% are observed, which validates the theoretical model of velocity filtering. Finally, Rayleigh scattering into an optical cavity is investigated as an alternative, non-destructive detection method for cold molecules. Comparing the rate of scattering into the fundamental cavity mode to that into the same mode under free-space conditions, an enhancement by a factor of up to 38 is observed for room-temperature gases. This Purcell-like enhancement is explained by interference of electromagnetic fields scattered by a classical driven dipole oscillator in the resonator. (orig.)

  2. Object-Based Change Detection in Urban Areas: The Effects of Segmentation Strategy, Scale, and Feature Space on Unsupervised Methods

    Directory of Open Access Journals (Sweden)

    Lei Ma

    2016-09-01

    Full Text Available Object-based change detection (OBCD has recently been receiving increasing attention as a result of rapid improvements in the resolution of remote sensing data. However, some OBCD issues relating to the segmentation of high-resolution images remain to be explored. For example, segmentation units derived using different segmentation strategies, segmentation scales, feature space, and change detection methods have rarely been assessed. In this study, we have tested four common unsupervised change detection methods using different segmentation strategies and a series of segmentation scale parameters on two WorldView-2 images of urban areas. We have also evaluated the effect of adding extra textural and Normalized Difference Vegetation Index (NDVI information instead of using only spectral information. Our results indicated that change detection methods performed better at a medium scale than at a fine scale where close to the pixel size. Multivariate Alteration Detection (MAD always outperformed the other methods tested, at the same confidence level. The overall accuracy appeared to benefit from using a two-date segmentation strategy rather than single-date segmentation. Adding textural and NDVI information appeared to reduce detection accuracy, but the magnitude of this reduction was not consistent across the different unsupervised methods and segmentation strategies. We conclude that a two-date segmentation strategy is useful for change detection in high-resolution imagery, but that the optimization of thresholds is critical for unsupervised change detection methods. Advanced methods need be explored that can take advantage of additional textural or other parameters.

  3. Simulation of space-borne tsunami detection using GNSS-Reflectometry applied to tsunamis in the Indian Ocean

    Directory of Open Access Journals (Sweden)

    R. Stosius

    2010-06-01

    Full Text Available Within the German-Indonesian Tsunami Early Warning System project GITEWS (Rudloff et al., 2009, a feasibility study on a future tsunami detection system from space has been carried out. The Global Navigation Satellite System Reflectometry (GNSS-R is an innovative way of using reflected GNSS signals for remote sensing, e.g. sea surface altimetry. In contrast to conventional satellite radar altimetry, multiple height measurements within a wide field of view can be made simultaneously. With a dedicated Low Earth Orbit (LEO constellation of satellites equipped with GNSS-R, densely spaced sea surface height measurements could be established to detect tsunamis. This simulation study compares the Walker and the meshed comb constellation with respect to their global reflection point distribution. The detection performance of various LEO constellation scenarios with GPS, GLONASS and Galileo as signal sources is investigated. The study concentrates on the detection performance for six historic tsunami events in the Indian Ocean generated by earthquakes of different magnitudes, as well as on different constellation types and orbit parameters. The GNSS-R carrier phase is compared with the PARIS or code altimetry approach. The study shows that Walker constellations have a much better reflection point distribution compared to the meshed comb constellation. Considering simulation assumptions and assuming technical feasibility it can be demonstrated that strong tsunamis with magnitudes (M ≥8.5 can be detected with certainty from any orbit altitude within 15–25 min by a 48/8 or 81/9 Walker constellation if tsunami waves of 20 cm or higher can be detected by space-borne GNSS-R. The carrier phase approach outperforms the PARIS altimetry approach especially at low orbit altitudes and for a low number of LEO satellites.

  4. [Detection and clinical value of epithelial cellular adhesion molecule (EpCAM) mRNA positive circulating tumor cells in metastatic breast cancer].

    Science.gov (United States)

    Yan, Ying; Cheng, Jian-ping; Di, Li-jun; Song, Guo-hong; Ren, Jun

    2012-04-18

    To test for circulating tumor cells (CTCs) relying on epithelial cellular adhesion molecule (EpCAM) expression in metastatic breast cancer by quantitative real-time reverse transcription-PCR. In the study,47 metastatic breast cancer patients were evaluated by quantitative real-time PCR for detecting EpCAM mRNA. In addition, analyses were carried out for their correlation with patients' clinicopathologic features, response, and the time to progression (TTP). The sensitivity of EpCAM mRNA in the metastatic breast cancer patients was about 40%. However, the specificity of EpCAM mRNA for 20 healthy controls was 100%. TTP was calculated, and compared with that between EpCAM mRNA-positive and EpCAM mRNA-negative groups. For the retrospective study, the median TTP was 7.1 months and 11.1 months (P=0.013) for patients with EpCAM mRNA-positive and EpCAM mRNA-negative, respectively, after the first cycle chemotherapy. Moreover, a statistically significant correlation was demonstrated between EpCAM mRNA and TTP in patients who underwent the first or the second-line chemotherapy (P=0.018), but there was no significance in the patients pretreated with two or more previous chemotherapy lines (P=0.471). This study provides evidence of the presence of EpCAM mRNA in approximately 40% of patients with metastatic breast cancer. There is a strong correlation between EpCAM mRNA results after the first cycle therapy and TTP in metastatic breast cancer patients, and EpCAM mRNA positive after chemotherapy may predict shorter TTP.

  5. Performance Evaluation of Target Detection with a Near-Space Vehicle-Borne Radar in Blackout Condition

    Directory of Open Access Journals (Sweden)

    Yanpeng Li

    2016-01-01

    Full Text Available Radar is a very important sensor in surveillance applications. Near-space vehicle-borne radar (NSVBR is a novel installation of a radar system, which offers many benefits, like being highly suited to the remote sensing of extremely large areas, having a rapidly deployable capability and having low vulnerability to electronic countermeasures. Unfortunately, a target detection challenge arises because of complicated scenarios, such as nuclear blackout, rain attenuation, etc. In these cases, extra care is needed to evaluate the detection performance in blackout situations, since this a classical problem along with the application of an NSVBR. However, the existing evaluation measures are the probability of detection and the receiver operating curve (ROC, which cannot offer detailed information in such a complicated application. This work focuses on such requirements. We first investigate the effect of blackout on an electromagnetic wave. Performance evaluation indexes are then built: three evaluation indexes on the detection capability and two evaluation indexes on the robustness of the detection process. Simulation results show that the proposed measure will offer information on the detailed performance of detection. These measures are therefore very useful in detecting the target of interest in a remote sensing system and are helpful for both the NSVBR designers and users.

  6. Performance Evaluation of Target Detection with a Near-Space Vehicle-Borne Radar in Blackout Condition.

    Science.gov (United States)

    Li, Yanpeng; Li, Xiang; Wang, Hongqiang; Deng, Bin; Qin, Yuliang

    2016-01-06

    Radar is a very important sensor in surveillance applications. Near-space vehicle-borne radar (NSVBR) is a novel installation of a radar system, which offers many benefits, like being highly suited to the remote sensing of extremely large areas, having a rapidly deployable capability and having low vulnerability to electronic countermeasures. Unfortunately, a target detection challenge arises because of complicated scenarios, such as nuclear blackout, rain attenuation, etc. In these cases, extra care is needed to evaluate the detection performance in blackout situations, since this a classical problem along with the application of an NSVBR. However, the existing evaluation measures are the probability of detection and the receiver operating curve (ROC), which cannot offer detailed information in such a complicated application. This work focuses on such requirements. We first investigate the effect of blackout on an electromagnetic wave. Performance evaluation indexes are then built: three evaluation indexes on the detection capability and two evaluation indexes on the robustness of the detection process. Simulation results show that the proposed measure will offer information on the detailed performance of detection. These measures are therefore very useful in detecting the target of interest in a remote sensing system and are helpful for both the NSVBR designers and users.

  7. Detection of Weak Spots in Benchmarks Memory Space by using PCA and CA

    Directory of Open Access Journals (Sweden)

    Abdul Kareem PARCHUR

    2010-12-01

    Full Text Available This paper describes the weak spots in SPEC CPU INT 2006 Benchmarks memory space by using Principal Component Analysis and Cluster Analysis. We used recently published SPEC CPU INT 2006 Benchmark scores of AMD Opteron 2000+ and AMD Opteron 8000+ series processors. The four most significant PCs, which are retained for 72.6% of the variance, PC2, PC3, and PC4 covers 26.5%, 2.9%, 0.91% and 0.019% variance respectively. The dendrogram is useful to identify the similarities and dissimilarities between the benchmarks in workload space. These results and analysis can be used by performance engineers, scientists and developers to better understand the benchmark behavior in workload space and to design a Benchmark Suite that covers the complete workload space.

  8. Enabling Global Lunar Sample Return and Life-Detection Studies Using a Deep-Space Gateway

    Science.gov (United States)

    Cohen, B. A.; Eigenbrode, J. A.; Young, K. E.; Bleacher, J. E.; Trainer, M. E.

    2018-02-01

    The Deep Space Gateway could uniquely enable a lunar robotic sampling campaign that would provide incredible science return as well as feed forward to Mars and Europa by testing instrument sterility and ability to distinguish biogenic signals.

  9. Ultra-Low Noise Quad Photoreceiver for Space Based Laser Interferometric Gravity Wave Detection, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design and develop 2x2 quad p-i-n InGaAs Photoreceivers having the following characteristics: (a) Active area diameter 0.75 mm; (b) Wavelength coverage...

  10. Kepler detected gravity-mode period spacings in a red giant star

    NARCIS (Netherlands)

    Beck, P.G.; Bedding, T.R.; Mosser, B.; Stello, D.; Garcia, R.A.; Kallinger, T.; Hekker, S.; Elsworth, Y.; Frandsen, S.; Carrier, F.; de Ridder, J.; Aerts, C.; White, T.R.; Huber, D.; Dupret, M. A.; Montalban, J.; Miglio, A.; Noels, A.; Chaplin, W.J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Gilliland, R.L.; Brown, T.M.; Kawaler, S.D.; Mathur, S.; Jenkins, J.M.

    2011-01-01

    Stellar interiors are inaccessible through direct observations. For this reason, helioseismologists made use of the Sun’s acoustic oscillation modes to tune models of its structure. The quest to detect modes that probe the solar core has been ongoing for decades. We report the detection of mixed

  11. On the Detection and Tracking of Space Debris Using the Murchison Widefield Array. I. Simulations and Test Observations Demonstrate Feasibility

    Science.gov (United States)

    Tingay, S. J.; Kaplan, D. L.; McKinley, B.; Briggs, F.; Wayth, R. B.; Hurley-Walker, N.; Kennewell, J.; Smith, C.; Zhang, K.; Arcus, W.; Bhat, N. D. R.; Emrich, D.; Herne, D.; Kudryavtseva, N.; Lynch, M.; Ord, S. M.; Waterson, M.; Barnes, D. G.; Bell, M.; Gaensler, B. M.; Lenc, E.; Bernardi, G.; Greenhill, L. J.; Kasper, J. C.; Bowman, J. D.; Jacobs, D.; Bunton, J. D.; deSouza, L.; Koenig, R.; Pathikulangara, J.; Stevens, J.; Cappallo, R. J.; Corey, B. E.; Kincaid, B. B.; Kratzenberg, E.; Lonsdale, C. J.; McWhirter, S. R.; Rogers, A. E. E.; Salah, J. E.; Whitney, A. R.; Deshpande, A.; Prabu, T.; Udaya Shankar, N.; Srivani, K. S.; Subrahmanyan, R.; Ewall-Wice, A.; Feng, L.; Goeke, R.; Morgan, E.; Remillard, R. A.; Williams, C. L.; Hazelton, B. J.; Morales, M. F.; Johnston-Hollitt, M.; Mitchell, D. A.; Procopio, P.; Riding, J.; Webster, R. L.; Wyithe, J. S. B.; Oberoi, D.; Roshi, A.; Sault, R. J.; Williams, A.

    2013-10-01

    The Murchison Widefield Array (MWA) is a new low-frequency interferometric radio telescope, operating in the benign radio frequency environment of remote Western Australia. The MWA is the low-frequency precursor to the Square Kilometre Array (SKA) and is the first of three SKA precursors to be operational, supporting a varied science mission ranging from the attempted detection of the Epoch of Reionization to the monitoring of solar flares and space weather. In this paper we explore the possibility that the MWA can be used for the purposes of Space Situational Awareness (SSA). In particular we propose that the MWA can be used as an element of a passive radar facility operating in the frequency range 87.5-108 MHz (the commercial FM broadcast band). In this scenario the MWA can be considered the receiving element in a bi-static radar configuration, with FM broadcast stations serving as non-cooperative transmitters. The FM broadcasts propagate into space, are reflected off debris in Earth orbit, and are received at the MWA. The imaging capabilities of the MWA can be used to simultaneously detect multiple pieces of space debris, image their positions on the sky as a function of time, and provide tracking data that can be used to determine orbital parameters. Such a capability would be a valuable addition to Australian and global SSA assets, in terms of southern and eastern hemispheric coverage. We provide a feasibility assessment of this proposal, based on simple calculations and electromagnetic simulations, that shows that the detection of sub-meter size debris should be possible (debris radius of >0.5 m to ~1000 km altitude). We also present a proof-of-concept set of observations that demonstrate the feasibility of the proposal, based on the detection and tracking of the International Space Station via reflected FM broadcast signals originating in southwest Western Australia. These observations broadly validate our calculations and simulations. We discuss some

  12. An Amplitude-Based Estimation Method for International Space Station (ISS) Leak Detection and Localization Using Acoustic Sensor Networks

    Science.gov (United States)

    Tian, Jialin; Madaras, Eric I.

    2009-01-01

    The development of a robust and efficient leak detection and localization system within a space station environment presents a unique challenge. A plausible approach includes the implementation of an acoustic sensor network system that can successfully detect the presence of a leak and determine the location of the leak source. Traditional acoustic detection and localization schemes rely on the phase and amplitude information collected by the sensor array system. Furthermore, the acoustic source signals are assumed to be airborne and far-field. Likewise, there are similar applications in sonar. In solids, there are specialized methods for locating events that are used in geology and in acoustic emission testing that involve sensor arrays and depend on a discernable phase front to the received signal. These methods are ineffective if applied to a sensor detection system within the space station environment. In the case of acoustic signal location, there are significant baffling and structural impediments to the sound path and the source could be in the near-field of a sensor in this particular setting.

  13. Dengue fever occurrence and vector detection by larval survey, ovitrap and MosquiTRAP: a space-time clusters analysis.

    Science.gov (United States)

    de Melo, Diogo Portella Ornelas; Scherrer, Luciano Rios; Eiras, Álvaro Eduardo

    2012-01-01

    The use of vector surveillance tools for preventing dengue disease requires fine assessment of risk, in order to improve vector control activities. Nevertheless, the thresholds between vector detection and dengue fever occurrence are currently not well established. In Belo Horizonte (Minas Gerais, Brazil), dengue has been endemic for several years. From January 2007 to June 2008, the dengue vector Aedes (Stegomyia) aegypti was monitored by ovitrap, the sticky-trap MosquiTRAP™ and larval surveys in an study area in Belo Horizonte. Using a space-time scan for clusters detection implemented in SaTScan software, the vector presence recorded by the different monitoring methods was evaluated. Clusters of vectors and dengue fever were detected. It was verified that ovitrap and MosquiTRAP vector detection methods predicted dengue occurrence better than larval survey, both spatially and temporally. MosquiTRAP and ovitrap presented similar results of space-time intersections to dengue fever clusters. Nevertheless ovitrap clusters presented longer duration periods than MosquiTRAP ones, less acuratelly signalizing the dengue risk areas, since the detection of vector clusters during most of the study period was not necessarily correlated to dengue fever occurrence. It was verified that ovitrap clusters occurred more than 200 days (values ranged from 97.0±35.35 to 283.0±168.4 days) before dengue fever clusters, whereas MosquiTRAP clusters preceded dengue fever clusters by approximately 80 days (values ranged from 65.5±58.7 to 94.0±14. 3 days), the former showing to be more temporally precise. Thus, in the present cluster analysis study MosquiTRAP presented superior results for signaling dengue transmission risks both geographically and temporally. Since early detection is crucial for planning and deploying effective preventions, MosquiTRAP showed to be a reliable tool and this method provides groundwork for the development of even more precise tools.

  14. Hotspot detection using space-time scan statistics on children under five years of age in Depok

    Science.gov (United States)

    Verdiana, Miranti; Widyaningsih, Yekti

    2017-03-01

    Some problems that affect the health level in Depok is the high malnutrition rates from year to year and the more spread infectious and non-communicable diseases in some areas. Children under five years old is a vulnerable part of population to get the malnutrition and diseases. Based on this reason, it is important to observe the location and time, where and when, malnutrition in Depok happened in high intensity. To obtain the location and time of the hotspots of malnutrition and diseases that attack children under five years old, space-time scan statistics method can be used. Space-time scan statistic is a hotspot detection method, where the area and time of information and time are taken into account simultaneously in detecting the hotspots. This method detects a hotspot with a cylindrical scanning window: the cylindrical pedestal describes the area, and the height of cylinder describe the time. Cylinders formed is a hotspot candidate that may occur, which require testing of hypotheses, whether a cylinder can be summed up as a hotspot. Hotspot detection in this study carried out by forming a combination of several variables. Some combination of variables provides hotspot detection results that tend to be the same, so as to form groups (clusters). In the case of infant health level in Depok city, Beji health care center region in 2011-2012 is a hotspot. According to the combination of the variables used in the detection of hotspots, Beji health care center is most frequently as a hotspot. Hopefully the local government can take the right policy to improve the health level of children under five in the city of Depok.

  15. Dengue Fever Occurrence and Vector Detection by Larval Survey, Ovitrap and MosquiTRAP: A Space-Time Clusters Analysis

    Science.gov (United States)

    de Melo, Diogo Portella Ornelas; Scherrer, Luciano Rios; Eiras, Álvaro Eduardo

    2012-01-01

    The use of vector surveillance tools for preventing dengue disease requires fine assessment of risk, in order to improve vector control activities. Nevertheless, the thresholds between vector detection and dengue fever occurrence are currently not well established. In Belo Horizonte (Minas Gerais, Brazil), dengue has been endemic for several years. From January 2007 to June 2008, the dengue vector Aedes (Stegomyia) aegypti was monitored by ovitrap, the sticky-trap MosquiTRAP™ and larval surveys in an study area in Belo Horizonte. Using a space-time scan for clusters detection implemented in SaTScan software, the vector presence recorded by the different monitoring methods was evaluated. Clusters of vectors and dengue fever were detected. It was verified that ovitrap and MosquiTRAP vector detection methods predicted dengue occurrence better than larval survey, both spatially and temporally. MosquiTRAP and ovitrap presented similar results of space-time intersections to dengue fever clusters. Nevertheless ovitrap clusters presented longer duration periods than MosquiTRAP ones, less acuratelly signalizing the dengue risk areas, since the detection of vector clusters during most of the study period was not necessarily correlated to dengue fever occurrence. It was verified that ovitrap clusters occurred more than 200 days (values ranged from 97.0±35.35 to 283.0±168.4 days) before dengue fever clusters, whereas MosquiTRAP clusters preceded dengue fever clusters by approximately 80 days (values ranged from 65.5±58.7 to 94.0±14. 3 days), the former showing to be more temporally precise. Thus, in the present cluster analysis study MosquiTRAP presented superior results for signaling dengue transmission risks both geographically and temporally. Since early detection is crucial for planning and deploying effective preventions, MosquiTRAP showed to be a reliable tool and this method provides groundwork for the development of even more precise tools. PMID:22848729

  16. Detection of Tuberculosis Infection Hotspots Using Activity Spaces Based Spatial Approach in an Urban Tokyo, from 2003 to 2011.

    Science.gov (United States)

    Izumi, Kiyohiko; Ohkado, Akihiro; Uchimura, Kazuhiro; Murase, Yoshiro; Tatsumi, Yuriko; Kayebeta, Aya; Watanabe, Yu; Ishikawa, Nobukatsu

    2015-01-01

    Identifying ongoing tuberculosis infection sites is crucial for breaking chains of transmission in tuberculosis-prevalent urban areas. Previous studies have pointed out that detection of local accumulation of tuberculosis patients based on their residential addresses may be limited by a lack of matching between residences and tuberculosis infection sites. This study aimed to identify possible tuberculosis hotspots using TB genotype clustering statuses and a concept of "activity space", a place where patients spend most of their waking hours. We further compared the spatial distribution by different residential statuses and describe urban environmental features of the detected hotspots. Culture-positive tuberculosis patients notified to Shinjuku city from 2003 to 2011 were enrolled in this case-based cross-sectional study, and their demographic and clinical information, TB genotype clustering statuses, and activity space were collected. Spatial statistics (Global Moran's I and Getis-Ord Gi* statistics) identified significant hotspots in 152 census tracts, and urban environmental features and tuberculosis patients' characteristics in these hotspots were assessed. Of the enrolled 643 culture-positive tuberculosis patients, 416 (64.2%) were general inhabitants, 42 (6.5%) were foreign-born people, and 184 were homeless people (28.6%). The percentage of overall genotype clustering was 43.7%. Genotype-clustered general inhabitants and homeless people formed significant hotspots around a major railway station, whereas the non-clustered general inhabitants formed no hotspots. This suggested the detected hotspots of activity spaces may reflect ongoing tuberculosis transmission sites and were characterized by smaller residential floor size and a higher proportion of non-working households. Activity space-based spatial analysis suggested possible TB transmission sites around the major railway station and it can assist in further comprehension of TB transmission dynamics in an

  17. Detection of renal tissue and urinary tract proteins in the human urine after space flight.

    Science.gov (United States)

    Pastushkova, Lyudmila Kh; Kireev, Kirill S; Kononikhin, Alexey S; Tiys, Evgeny S; Popov, Igor A; Starodubtseva, Natalia L; Dobrokhotov, Igor V; Ivanisenko, Vladimir A; Larina, Irina M; Kolchanov, Nicolay A; Nikolaev, Evgeny N

    2013-01-01

    The urine protein composition samples of ten Russian cosmonauts (male, aged of 35 up to 51) performed long flight missions and varied from 169 up to 199 days on the International Space Station (ISS) were analyzed. As a control group, urine samples of six back-up cosmonauts were analyzed. We used proteomic techniques to obtain data and contemporary bioinformatics approaches to perform the analysis. From the total number of identified proteins (238) in our data set, 129 were associated with a known tissue origin. Preflight samples contained 92 tissue-specific proteins, samples obtained on Day 1 after landing had 90 such proteins, while Day 7 samples offered 95 tissue-specific proteins. Analysis showed that consistently present proteins in urine (under physiological conditions and after space flight) are cubilin, epidermal growth factor, kallikrein-1, kininogen-1, megalin, osteopontin, vitamin K-dependent protein Z, uromodulin. Variably present proteins consists of: Na(+)/K(+) ATPase subunit gamma, β-defensin-1, dipeptidyl peptidase 4, maltasa-glucoamilasa, cadherin-like protein, neutral endopeptidase and vascular cell adhesion protein 1. And only three renal proteins were related to the space flight factors. They were not found in the pre-flight samples and in the back-up cosmonaut urine, but were found in the urine samples after space flight: AFAM (afamin), AMPE (aminopeptidase A) and AQP2 (aquaporin-2). This data related with physiological readaptation of water-salt balance. The proteomic analysis of urine samples in different phases of space missions with bioinformation approach to protein identification provides new data relative to biomechemical mechanism of kidney functioning after space flight.

  18. Detection of renal tissue and urinary tract proteins in the human urine after space flight.

    Directory of Open Access Journals (Sweden)

    Lyudmila Kh Pastushkova

    Full Text Available The urine protein composition samples of ten Russian cosmonauts (male, aged of 35 up to 51 performed long flight missions and varied from 169 up to 199 days on the International Space Station (ISS were analyzed. As a control group, urine samples of six back-up cosmonauts were analyzed. We used proteomic techniques to obtain data and contemporary bioinformatics approaches to perform the analysis. From the total number of identified proteins (238 in our data set, 129 were associated with a known tissue origin. Preflight samples contained 92 tissue-specific proteins, samples obtained on Day 1 after landing had 90 such proteins, while Day 7 samples offered 95 tissue-specific proteins. Analysis showed that consistently present proteins in urine (under physiological conditions and after space flight are cubilin, epidermal growth factor, kallikrein-1, kininogen-1, megalin, osteopontin, vitamin K-dependent protein Z, uromodulin. Variably present proteins consists of: Na(+/K(+ ATPase subunit gamma, β-defensin-1, dipeptidyl peptidase 4, maltasa-glucoamilasa, cadherin-like protein, neutral endopeptidase and vascular cell adhesion protein 1. And only three renal proteins were related to the space flight factors. They were not found in the pre-flight samples and in the back-up cosmonaut urine, but were found in the urine samples after space flight: AFAM (afamin, AMPE (aminopeptidase A and AQP2 (aquaporin-2. This data related with physiological readaptation of water-salt balance. The proteomic analysis of urine samples in different phases of space missions with bioinformation approach to protein identification provides new data relative to biomechemical mechanism of kidney functioning after space flight.

  19. On-Line Detection of Distributed Attacks from Space-Time Network Flow Patterns

    National Research Council Canada - National Science Library

    Baras, J. S; Cardenas, A. A; Ramezani, V

    2003-01-01

    .... The directionality of the change in a network flow is assumed to have an objective or target. The particular problem of detecting distributed denial of service attacks from distributed observations is presented as a working framework...

  20. Space Object Detection and Tracking Within a Finite Set Statistics Framework

    Science.gov (United States)

    2017-04-13

    detection statistics . . . . . . . 18 7 Estimated results using the standard JoTT filter. . . . . . . . . . . . . . . . . . . . . . . . 19 8 Estimated...Versions of the JoTT Filter The standard JoTT filter, requires the parameters for the detection statistics to be specified a priori, namely the...iteration, the median (Īblock) and standard deviation (σblock) of the pixel intensities are computed. Pixel intensities, which differ significantly from the

  1. Marginal space learning for medical image analysis efficient detection and segmentation of anatomical structures

    CERN Document Server

    Zheng, Yefeng

    2014-01-01

    Presents an award winning image analysis technology (Thomas Edison Patent Award, MICCAI Young Investigator Award) that achieves object detection and segmentation with state-of-the-art accuracy and efficiency Flexible, machine learning-based framework, applicable across multiple anatomical structures and imaging modalities Thirty five clinical applications on detecting and segmenting anatomical structures such as heart chambers and valves, blood vessels, liver, kidney, prostate, lymph nodes, and sub-cortical brain structures, in CT, MRI, X-Ray and Ultrasound.

  2. Prototype of microbolometer thermal infrared camera for forest fire detection from space

    Science.gov (United States)

    Guerin, Francois; Dantes, Didier; Bouzou, Nathalie; Chorier, Philippe; Bouchardy, Anne-Marie; Rollin, Joël.

    2017-11-01

    The contribution of the thermal infrared (TIR) camera to the Earth observation FUEGO mission is to participate; to discriminate the clouds and smoke; to detect the false alarms of forest fires; to monitor the forest fires. Consequently, the camera needs a large dynamic range of detectable radiances. A small volume, low mass and power are required by the small FUEGO payload. These specifications can be attractive for other similar missions.

  3. Enzyme molecules in solitary confinement.

    Science.gov (United States)

    Liebherr, Raphaela B; Gorris, Hans H

    2014-09-12

    Large arrays of homogeneous microwells each defining a femtoliter volume are a versatile platform for monitoring the substrate turnover of many individual enzyme molecules in parallel. The high degree of parallelization enables the analysis of a statistically representative enzyme population. Enclosing individual enzyme molecules in microwells does not require any surface immobilization step and enables the kinetic investigation of enzymes free in solution. This review describes various microwell array formats and explores their applications for the detection and investigation of single enzyme molecules. The development of new fabrication techniques and sensitive detection methods drives the field of single molecule enzymology. Here, we introduce recent progress in single enzyme molecule analysis in microwell arrays and discuss the challenges and opportunities.

  4. Flexible feature-space-construction architecture and its VLSI implementation for multi-scale object detection

    Science.gov (United States)

    Luo, Aiwen; An, Fengwei; Zhang, Xiangyu; Chen, Lei; Huang, Zunkai; Jürgen Mattausch, Hans

    2018-04-01

    Feature extraction techniques are a cornerstone of object detection in computer-vision-based applications. The detection performance of vison-based detection systems is often degraded by, e.g., changes in the illumination intensity of the light source, foreground-background contrast variations or automatic gain control from the camera. In order to avoid such degradation effects, we present a block-based L1-norm-circuit architecture which is configurable for different image-cell sizes, cell-based feature descriptors and image resolutions according to customization parameters from the circuit input. The incorporated flexibility in both the image resolution and the cell size for multi-scale image pyramids leads to lower computational complexity and power consumption. Additionally, an object-detection prototype for performance evaluation in 65 nm CMOS implements the proposed L1-norm circuit together with a histogram of oriented gradients (HOG) descriptor and a support vector machine (SVM) classifier. The proposed parallel architecture with high hardware efficiency enables real-time processing, high detection robustness, small chip-core area as well as low power consumption for multi-scale object detection.

  5. Observations of the Hubble Deep Field with the Infrared Space Observatory .2. Source detection and photometry

    DEFF Research Database (Denmark)

    Goldschmidt, P.; Oliver, S.J.; Serjeant, S.B.G.

    1997-01-01

    We present positions and fluxes of point sources found in the Infrared Space Observatory (ISO) images of the Hubble Deep Field (HDF) at 6.7 and 15 mu m. We have constructed algorithmically selected 'complete' flux-limited samples of 19 sources in the 15-mu m image, and seven sources in the 6.7-mu m...

  6. Unsupervised building detection from irregularly spaced LiDAR and aerial imagery

    Science.gov (United States)

    Shorter, Nicholas Sven

    As more data sources containing 3-D information are becoming available, an increased interest in 3-D imaging has emerged. Among these is the 3-D reconstruction of buildings and other man-made structures. A necessary preprocessing step is the detection and isolation of individual buildings that subsequently can be reconstructed in 3-D using various methodologies. Applications for both building detection and reconstruction have commercial use for urban planning, network planning for mobile communication (cell phone tower placement), spatial analysis of air pollution and noise nuisances, microclimate investigations, geographical information systems, security services and change detection from areas affected by natural disasters. Building detection and reconstruction are also used in the military for automatic target recognition and in entertainment for virtual tourism. Previously proposed building detection and reconstruction algorithms solely utilized aerial imagery. With the advent of Light Detection and Ranging (LiDAR) systems providing elevation data, current algorithms explore using captured LiDAR data as an additional feasible source of information. Additional sources of information can lead to automating techniques (alleviating their need for manual user intervention) as well as increasing their capabilities and accuracy. Several building detection approaches surveyed in the open literature have fundamental weaknesses that hinder their use; such as requiring multiple data sets from different sensors, mandating certain operations to be carried out manually, and limited functionality to only being able to detect certain types of buildings. In this work, a building detection system is proposed and implemented which strives to overcome the limitations seen in existing techniques. The developed framework is flexible in that it can perform building detection from just LiDAR data (first or last return), or just nadir, color aerial imagery. If data from both LiDAR and

  7. A Benchmark of Lidar-Based Single Tree Detection Methods Using Heterogeneous Forest Data from the Alpine Space

    Directory of Open Access Journals (Sweden)

    Lothar Eysn

    2015-05-01

    Full Text Available In this study, eight airborne laser scanning (ALS-based single tree detection methods are benchmarked and investigated. The methods were applied to a unique dataset originating from different regions of the Alpine Space covering different study areas, forest types, and structures. This is the first benchmark ever performed for different forests within the Alps. The evaluation of the detection results was carried out in a reproducible way by automatically matching them to precise in situ forest inventory data using a restricted nearest neighbor detection approach. Quantitative statistical parameters such as percentages of correctly matched trees and omission and commission errors are presented. The proposed automated matching procedure presented herein shows an overall accuracy of 97%. Method based analysis, investigations per forest type, and an overall benchmark performance are presented. The best matching rate was obtained for single-layered coniferous forests. Dominated trees were challenging for all methods. The overall performance shows a matching rate of 47%, which is comparable to results of other benchmarks performed in the past. The study provides new insight regarding the potential and limits of tree detection with ALS and underlines some key aspects regarding the choice of method when performing single tree detection for the various forest types encountered in alpine regions.

  8. A Design Space Exploration Framework for ANN-Based Fault Detection in Hardware Systems

    Directory of Open Access Journals (Sweden)

    Andreas G. Savva

    2017-01-01

    Full Text Available This work presents a design exploration framework for developing a high level Artificial Neural Network (ANN for fault detection in hardware systems. ANNs can be used for fault detection purposes since they have excellent characteristics such as generalization capability, robustness, and fault tolerance. Designing an ANN in order to be used for fault detection purposes includes different parameters. Through this work, those parameters are presented and analyzed based on simulations. Moreover, after the development of the ANN, in order to evaluate it, a case study scenario based on Networks on Chip is used for detection of interrouter link faults. Simulation results with various synthetic traffic models show that the proposed work can detect up to 96–99% of interrouter link faults with a delay less than 60 cycles. Added to this, the size of the ANN is kept relatively small and they can be implemented in hardware easily. Synthesis results indicate an estimated amount of 0.0523 mW power consumption per neuron for the implemented ANN when computing a complete cycle.

  9. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 12. Molecule Matters van der Waals Molecules - Noble Gas Clusters are London Molecules! E Arunan. Feature Article Volume 14 Issue 12 December 2009 pp 1210-1222 ...

  10. The clinical importance of expanded subarachnoid spaces detected by CT in early infancy

    International Nuclear Information System (INIS)

    Krusche, S.

    1982-01-01

    It depends on the clinical course and on follow-jup CT findings whether expansions of the subarachnoid space should be considered as pathological changes or as normal. There is no direct correlation between the degree of severity of the clinical symptoms on the one hand and the CT changes on the other. The clinical course and the follow-up CT images are found to be uncorrelated, too. CT findings alone are insufficient in predicting children's development. Especially in the case of unspecific changes, e.g. slight expansions of the subarachnoid space, cranial CT can only provide further proof of a suspected clinical diagnosis. The ventricular indices frequently used for CT interpretation can rarely be used as decision aids or as factors providing new information. (orig./MG) [de

  11. From Ground Truth to Space: Surface, Subsurface and Remote Observations Associated with Nuclear Test Detection

    Science.gov (United States)

    Sussman, A. J.; Anderson, D.; Burt, C.; Craven, J.; Kimblin, C.; McKenna, I.; Schultz-Fellenz, E. S.; Miller, E.; Yocky, D. A.; Haas, D.

    2016-12-01

    Underground nuclear explosions (UNEs) result in numerous signatures that manifest on a wide range of temporal and spatial scales. Currently, prompt signals, such as the detection of seismic waves provide only generalized locations and the timing and amplitude of non-prompt signals are difficult to predict. As such, research into improving the detection, location, and identification of suspect events has been conducted, resulting in advancement of nuclear test detection science. In this presentation, we demonstrate the scalar variably of surface and subsurface observables, briefly discuss current capabilities to locate, detect and characterize potential nuclear explosion locations, and explain how emergent technologies and amalgamation of disparate data sets will facilitate improved monitoring and verification. At the smaller scales, material and fracture characterization efforts on rock collected from legacy UNE sites and from underground experiments using chemical explosions can be incorporated into predictive modeling efforts. Spatial analyses of digital elevation models and orthoimagery of both modern conventional and legacy nuclear sites show subtle surface topographic changes and damage at nearby outcrops. Additionally, at sites where such technology cannot penetrate vegetative cover, it is possible to use the vegetation itself as both a companion signature reflecting geologic conditions and showing subsurface impacts to water, nutrients, and chemicals. Aerial systems based on RGB imagery, light detection and ranging, and hyperspectral imaging can allow for combined remote sensing modalities to perform pattern recognition and classification tasks. Finally, more remote systems such as satellite based synthetic aperture radar and satellite imagery are other techniques in development for UNE site detection, location and characterization.

  12. Detection of a contact barrier by a temperature-modulated space-charge-limited current technique

    Czech Academy of Sciences Publication Activity Database

    Zhivkov, I.; Biler, M.; Nešpůrek, Stanislav

    2007-01-01

    Roč. 9, č. 2 (2007), s. 483-485 ISSN 1454-4164. [International School on Condensed Matter Physics /14./. Varna, 17.09.2006-22.09.2006] R&D Projects: GA MŠk OC 138 Institutional research plan: CEZ:AV0Z40500505 Keywords : poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene] vinylene * space-charge-limited current * Schottky barrier Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.827, year: 2007

  13. A Study of Dim Object Detection for the Space Surveillance Telescope

    Science.gov (United States)

    2013-03-21

    philosophical conundrum. Thus statistically-based methods that decide the relative likelihood of condition are appropriate. Given the expense of...research were taken while the SST was located at Atom Site in the White Sands Missile Range, above 8000 feet. At the seeing conditions at the Atom Site...operator for transforming the operand into ( , )u v , the frequency space. This binary screen does not account for any obscurations or imperfections in

  14. A Fiber-Optic Sensor for Leak Detection in a Space Environment

    Science.gov (United States)

    Sinko, John E.; Korman, Valentin; Hendrickson, Adam; Polzin, Kurt A.

    2009-01-01

    A miniature fiber-optic, laser-based, interferometric leak detector is presented for application as a means to detect on-orbit gas leaks. The sensor employs a fiber-coupled modified Michelson interferometer to detect gas leaks by measuring an increase in gas density in the sensing region. Monitoring changes in the fringe pattern output by the interferometer allows for direct measurement of the gas density in the sensing region and, under the assumption of an equation of state, this can be used to obtain a pressure measurement. Measurements obtained over a pressure range from 20 mtorr to 760 torr using a prototypical interferometer on working gases of air, nitrogen, argon, and helium generally exhibit agreement with a theoretical prediction of the pressure increase required before an interference fringe completely moves over the detector. Additional measurements performed on various gases demonstrate the range of detectable species, measuring sub-torr pressure changes in the process. A high-fidelity measurement places the ultimate pressure resolution for this particular sensor configuration in the 10 mtorr range. Time-resolved data prove the capability of this sensor to detect fast gas flow phenomena associated with transients and pressure waves.

  15. An instrument for real time detection of contamination in space environmental tests chambers

    Science.gov (United States)

    Richmond, R. G.; Harmon, H. N.

    1972-01-01

    An instrument for in situ vacuum detection of surface reflectance changes at 1216A was designed. Using successive reflections, this instrument is more sensitive as an indicator of reflectance changes than similar instruments having only a single reflection. The selection of each component of the instrument and its operational performance is discussed.

  16. Using space-time features to improve detection of forest disturbances from Landsat time series

    NARCIS (Netherlands)

    Hamunyela, E.; Reiche, J.; Verbesselt, J.; Herold, M.

    2017-01-01

    Current research on forest change monitoring using medium spatial resolution Landsat satellite data aims for accurate and timely detection of forest disturbances. However, producing forest disturbance maps that have both high spatial and temporal accuracy is still challenging because of the

  17. Blowing snow detection in Antarctica, from space borne and ground-based remote sensing

    Science.gov (United States)

    Gossart, A.; Souverijns, N.; Lhermitte, S.; Lenaerts, J.; Gorodetskaya, I.; Schween, J. H.; Van Lipzig, N. P. M.

    2017-12-01

    Surface mass balance (SMB) strongly controls spatial and temporal variations in the Antarctic Ice Sheet (AIS) mass balance and its contribution to sea level rise. Currently, the scarcity of observational data and the challenges of climate modelling over the ice sheet limit our understanding of the processes controlling AIS SMB. Particularly, the impact of blowing snow on local SMB is not yet constrained and is subject to large uncertainties. To assess the impact of blowing snow on local SMB, we investigate the attenuated backscatter profiles from ceilometers at two East Antarctic locations in Dronning Maud Land. Ceilometers are robust ground-based remote sensing instruments that yield information on cloud base height and vertical structure, but also provide information on the particles present in the boundary layer. We developed a new algorithm to detect blowing snow (snow particles lifted by the wind from the surface to substantial height) from the ceilometer attenuated backscatter. The algorithm successfully allows to detect strong blowing snow signal from layers thicker than 15 m at the Princess Elisabeth (PE, (72°S, 23°E)) and Neumayer (70°S, 8° W) stations. Applying the algorithm to PE, we retrieve the frequency and annual cycle of blowing snow as well as discriminate between clear sky and overcast conditions during blowing snow. We further apply the blowing snow algorithm at PE to evaluate the blowing snow events detection by satellite imagery (Palm et al., 2011): the near-surface blowing snow layers are apparent in lidar backscatter profiles and enable snowdrift events detection (spatial and temporal frequency, height and optical depth). These data are processed from CALIPSO, at a high resolution (1x1 km digital elevation model). However, the remote sensing detection of blowing snow events by satellite is limited to layers of a minimal thickness of 20-30 m. In addition, thick clouds, mostly occurring during winter storms, can impede drifting snow

  18. Gravitational Wave (GW Classification, Space GW Detection Sensitivities and AMIGO (Astrodynamical Middle-frequency Interferometric GW Observatory

    Directory of Open Access Journals (Sweden)

    Ni Wei-Tou

    2018-01-01

    Full Text Available After first reviewing the gravitational wave (GW spectral classification. we discuss the sensitivities of GW detection in space aimed at low frequency band (100 nHz–100 mHz and middle frequency band (100 mHz–10 Hz. The science goals are to detect GWs from (i Supermassive Black Holes; (ii Extreme-Mass-Ratio Black Hole Inspirals; (iii Intermediate-Mass Black Holes; (iv Galactic Compact Binaries; (v Stellar-Size Black Hole Binaries; and (vi Relic GW Background. The detector proposals have arm length ranging from 100 km to 1.35×109 km (9 AU including (a Solar orbiting detectors and (b Earth orbiting detectors. We discuss especially the sensitivities in the frequency band 0.1-10 μHz and the middle frequency band (0.1 Hz–10 Hz. We propose and discuss AMIGO as an Astrodynamical Middlefrequency Interferometric GW Observatory.

  19. Quantum transport through aromatic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda, J. H., E-mail: judith.ojeda@uptc.edu.co [Instituto de Alta investigación, Universidad de Tarapaca, Casilla 7D Arica (Chile); Grupo de Física de Materiales, Escuela de Física, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Rey-González, R. R. [Departamento de Física, Universidad Nacional de Colombia, Bogotá D. C. (Colombia); Laroze, D. [Instituto de Alta investigación, Universidad de Tarapaca, Casilla 7D Arica (Chile)

    2013-12-07

    In this paper, we study the electronic transport properties through aromatic molecules connected to two semi-infinite leads. The molecules are in different geometrical configurations including arrays. Using a nearest neighbor tight-binding approach, the transport properties are analyzed into a Green's function technique within a real-space renormalization scheme. We calculate the transmission probability and the Current-Voltage characteristics as a function of a molecule-leads coupling parameter. Our results show different transport regimes for these systems, exhibiting metal-semiconductor-insulator transitions and the possibility to employ them in molecular devices.

  20. Applying the tools of chemistry (mass spectrometry and covalent modification by small molecule reagents) to the detection of prions and the study of their structure

    Science.gov (United States)

    Prions are molecular pathogens, able to convert a normal cellular prion protein PrPC into a prion PrPSc. The information necessary for this conversion is contained in the conformation of PrPSc. Mass spectrometry and small-molecule covalent reactions have recently been used to study prions. This w...

  1. OMG: Open Molecule Generator.

    Science.gov (United States)

    Peironcely, Julio E; Rojas-Chertó, Miguel; Fichera, Davide; Reijmers, Theo; Coulier, Leon; Faulon, Jean-Loup; Hankemeier, Thomas

    2012-09-17

    Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG), which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

  2. Terahertz Imaging and Backscatter Radiography Probability of Detection Study for Space Shuttle Foam Inspections

    Science.gov (United States)

    Ussery, Warren; Johnson, Kenneth; Walker, James; Rummel, Ward

    2008-01-01

    This slide presentation reviews the use of terahertz imaging and Backscatter Radiography in a probability of detection study of the foam on the external tank (ET) shedding and damaging the shuttle orbiter. Non-destructive Examination (NDE) is performed as one method of preventing critical foam debris during the launch. Conventional NDE methods for inspection of the foam are assessed and the deficiencies are reviewed. Two methods for NDE inspection are reviewed: Backscatter Radiography (BSX) and Terahertz (THZ) Imaging. The purpose of the Probability of Detection (POD) study was to assess performance and reliability of the use of BSX and or THZ as an appropriate NDE method. The study used a test article with inserted defects, and a sample of blanks included to test for false positives. The results of the POD study are reported.

  3. Fault Detection Algorithm based on Null-Space Analysis for On-Line Structural Health Monitoring

    OpenAIRE

    Yan, Ai-Min; Golinval, Jean-Claude; Marin, Frédéric

    2005-01-01

    Early diagnosis of structural damages or machinery malfunctions allows to reduce the maintenance cost of systems and to increase their reliability and safety. This paper addresses the damage detection problem by statistical analysis on output-only measurements of structures. The developed method is based on subspace analysis of the Hankel matrices constructed by vibration measurement data. The column active subspace of the Hankel matrix defined by the first principal components is orthonormal...

  4. Space Shuttle Main Engine Propellant Path Leak Detection Using Sequential Image Processing

    Science.gov (United States)

    Smith, L. Montgomery; Malone, Jo Anne; Crawford, Roger A.

    1995-01-01

    Initial research in this study using theoretical radiation transport models established that the occurrence of a leak is accompanies by a sudden but sustained change in intensity in a given region of an image. In this phase, temporal processing of video images on a frame-by-frame basis was used to detect leaks within a given field of view. The leak detection algorithm developed in this study consists of a digital highpass filter cascaded with a moving average filter. The absolute value of the resulting discrete sequence is then taken and compared to a threshold value to produce the binary leak/no leak decision at each point in the image. Alternatively, averaging over the full frame of the output image produces a single time-varying mean value estimate that is indicative of the intensity and extent of a leak. Laboratory experiments were conducted in which artificially created leaks on a simulated SSME background were produced and recorded from a visible wavelength video camera. This data was processed frame-by-frame over the time interval of interest using an image processor implementation of the leak detection algorithm. In addition, a 20 second video sequence of an actual SSME failure was analyzed using this technique. The resulting output image sequences and plots of the full frame mean value versus time verify the effectiveness of the system.

  5. Nearest Neighbor Search in the Metric Space of a Complex Network for Community Detection

    Directory of Open Access Journals (Sweden)

    Suman Saha

    2016-03-01

    Full Text Available The objective of this article is to bridge the gap between two important research directions: (1 nearest neighbor search, which is a fundamental computational tool for large data analysis; and (2 complex network analysis, which deals with large real graphs but is generally studied via graph theoretic analysis or spectral analysis. In this article, we have studied the nearest neighbor search problem in a complex network by the development of a suitable notion of nearness. The computation of efficient nearest neighbor search among the nodes of a complex network using the metric tree and locality sensitive hashing (LSH are also studied and experimented. For evaluation of the proposed nearest neighbor search in a complex network, we applied it to a network community detection problem. Experiments are performed to verify the usefulness of nearness measures for the complex networks, the role of metric tree and LSH to compute fast and approximate node nearness and the the efficiency of community detection using nearest neighbor search. We observed that nearest neighbor between network nodes is a very efficient tool to explore better the community structure of the real networks. Several efficient approximation schemes are very useful for large networks, which hardly made any degradation of results, whereas they save lot of computational times, and nearest neighbor based community detection approach is very competitive in terms of efficiency and time.

  6. Rapid and enhanced remote homology detection by cascading hidden Markov model searches in sequence space.

    Science.gov (United States)

    Kaushik, Swati; Nair, Anu G; Mutt, Eshita; Subramanian, Hari Prasanna; Sowdhamini, Ramanathan

    2016-02-01

    In the post-genomic era, automatic annotation of protein sequences using computational homology-based methods is highly desirable. However, often protein sequences diverge to an extent where detection of homology and automatic annotation transfer is not straightforward. Sophisticated approaches to detect such distant relationships are needed. We propose a new approach to identify deep evolutionary relationships of proteins to overcome shortcomings of the available methods. We have developed a method to identify remote homologues more effectively from any protein sequence database by using several cascading events with Hidden Markov Models (C-HMM). We have implemented clustering of hits and profile generation of hit clusters to effectively reduce the computational timings of the cascaded sequence searches. Our C-HMM approach could cover 94, 83 and 40% coverage at family, superfamily and fold levels, respectively, when applied on diverse protein folds. We have compared C-HMM with various remote homology detection methods and discuss the trade-offs between coverage and false positives. A standalone package implemented in Java along with a detailed documentation can be downloaded from https://github.com/RSLabNCBS/C-HMM SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online. mini@ncbs.res.in. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  7. Detection of extensive atmospheric showers at arrays of widely spaced detectors

    International Nuclear Information System (INIS)

    Anokhina, A.M.; Galkin, V.I.; Dedenko, L.G.; Nazarov, S.N.; Roganova, T.M.; Fedorova, G.F.

    1998-01-01

    Calculations that were performed on the basis of the quark-gluon-string model and which take into account interactions of neutral pions in the atmosphere and the Landau-Pomeranchuk-Migdal effect at high energies show that, at large distances from the axis of an extensive atmospheric shower, both the mean time delay and the time-pulse duration of the electron, muon, and Cherenkov-photon components of the shower may reach values of a few microseconds. To reduce errors both in the arrival direction of particles of primary cosmic radiation and in their energy, it is proposed to measure the duration of time pulses from all components carrying additional information about the distances to the shower axis, about hadron interactions at ultrahigh energies, and about the chemical composition of primary cosmic radiation. Arrays with 500-m spacing between detectors are preferable to those with 1500-m spacing, because the former allow time-pulse recording for all components at energies above 10 19 eV (for the latter, the energy threshold increases up to 10 20 eV)

  8. On low-complexity full-diversity detection of multi-user space-time coding

    KAUST Repository

    Ismail, Amr

    2013-06-01

    The incorporation of multiple input multiple output (MIMO) schemes in recent wireless communication standards paved the way to exploit the newly introduced dimension (i.e. space) to efficiently cancel the interference without requiring additional resources. In this paper, we focus on multiple input multiple ouitput (MIMO) multiple access channel (MAC) case and we answer the question about whether it is possible to suppress the interference in a MIMO MAC channel for completely blind users while achieving full-diversity with a simplified decoder in the affirmative. In fact, this goal can be attained by employing space-time block codes (STBC)s that achive full-diversity under partial interference cancellation (PIC). We derive sufficient conditions for a wide range of STBCs to achieve full-diversity under PIC group decoding with or without successive interference cancellation (SIC). Based on the provided design criteria we derive an upper-bound on the achievable rate for a class of codes. A two-user MIMO MAC interference cancellation scheme is presented and proved to achieve full-diversity under PIC group decoding. We compare our scheme to existing beamforming schemes with full or limit feedback. © 2013 IEEE.

  9. On Using a Space Telescope to Detect Weak-lensing Shear

    Science.gov (United States)

    Tung, Nathan; Wright, Edward

    2017-11-01

    Ignoring redshift dependence, the statistical performance of a weak-lensing survey is set by two numbers: the effective shape noise of the sources, which includes the intrinsic ellipticity dispersion and the measurement noise, and the density of sources that are useful for weak-lensing measurements. In this paper, we provide some general guidance for weak-lensing shear measurements from a “generic” space telescope by looking for the optimum wavelength bands to maximize the galaxy flux signal-to-noise ratio (S/N) and minimize ellipticity measurement error. We also calculate an effective galaxy number per square degree across different wavelength bands, taking into account the density of sources that are useful for weak-lensing measurements and the effective shape noise of sources. Galaxy data collected from the ultra-deep UltraVISTA Ks-selected and R-selected photometric catalogs (Muzzin et al. 2013) are fitted to radially symmetric Sérsic galaxy light profiles. The Sérsic galaxy profiles are then stretched to impose an artificial weak-lensing shear, and then convolved with a pure Airy Disk PSF to simulate imaging of weak gravitationally lensed galaxies from a hypothetical diffraction-limited space telescope. For our model calculations and sets of galaxies, our results show that the peak in the average galaxy flux S/N, the minimum average ellipticity measurement error, and the highest effective galaxy number counts all lie around the K-band near 2.2 μm.

  10. Application of Space Borne CO2 and Fluorescence Measurements to Detect Urban CO2 Emissions and Anthropogenic Influence on Vegetation

    Science.gov (United States)

    Paetzold, Johannes C.; Chen, Jia; Ruisinger, Veronika

    2017-04-01

    The Orbiting Carbon Observatory 2 (OCO-2) is a NASA satellite mission dedicated to make global, space-based observations of atmospheric, column-averaged carbon dioxide (XCO2). In addition, the OCO-2 also measures Solar Induced Chlorophyll Fluorescence (SIF). In our research we have studied the combination of OCO-2's XCO2 and SIF measurements for numerous urban areas on the different continents. Applying GIS and KML visualization techniques as well as statistical approaches we are able to reliably detect anthropogenic CO2 emissions in CO2 column concentration enhancements over urban areas. Moreover, we detect SIF decreases over urban areas compared to their rural vicinities. We are able to obtain those findings for urban areas on different continents, of diverse sizes, dissimilar topographies and urban constructions. Our statistical analysis finds robust XCO2 enhancements of up to 3 ppm for urban areas in Europe, Asia and North America. Furthermore, the analysis of SIF indicates that urban construction, population density and seasonality influence urban vegetation, which can be observed from space. Additionally, we find that OCO-2's SIF measurements have the potential to identify and approximate green areas within cities. For Berlin's Grunewald Forest as well as Mumbai's Sanjay Gandhi and Tungareshwar National Parks we observe enhancements in SIF measurements at sub-city scales.

  11. Optical phase-locked loop (OPLL) for free-space laser communications with heterodyne detection

    Science.gov (United States)

    Win, Moe Z.; Chen, Chien-Chung; Scholtz, Robert A.

    1991-01-01

    Several advantages of coherent free-space optical communications are outlined. Theoretical analysis is formulated for an OPLL disturbed by shot noise, modulation noise, and frequency noise consisting of a white component, a 1/f component, and a 1/f-squared component. Each of the noise components is characterized by its associated power spectral density. It is shown that the effect of modulation depends only on the ratio of loop bandwidth and data rate, and is negligible for an OPLL with loop bandwidth smaller than one fourth the data rate. Total phase error variance as a function of loop bandwidth is displayed for several values of carrier signal to noise ratio. Optimal loop bandwidth is also calculated as a function of carrier signal to noise ratio. An OPLL experiment is performed, where it is shown that the measured phase error variance closely matches the theoretical predictions.

  12. Single molecule tracking

    Science.gov (United States)

    Shera, E. Brooks

    1988-01-01

    A detection system is provided for identifying individual particles or molecules having characteristic emission in a flow train of the particles in a flow cell. A position sensitive sensor is located adjacent the flow cell in a position effective to detect the emissions from the particles within the flow cell and to assign spatial and temporal coordinates for the detected emissions. A computer is then enabled to predict spatial and temporal coordinates for the particle in the flow train as a function of a first detected emission. Comparison hardware or software then compares subsequent detected spatial and temporal coordinates with the predicted spatial and temporal coordinates to determine whether subsequently detected emissions originate from a particle in the train of particles. In one embodiment, the particles include fluorescent dyes which are excited to fluoresce a spectrum characteristic of the particular particle. Photones are emitted adjacent at least one microchannel plate sensor to enable spatial and temporal coordinates to be assigned. The effect of comparing detected coordinates with predicted coordinates is to define a moving sample volume which effectively precludes the effects of background emissions.

  13. Ion-Molecule Reaction Dynamics.

    Science.gov (United States)

    Meyer, Jennifer; Wester, Roland

    2017-05-05

    We review the recent advances in the investigation of the dynamics of ion-molecule reactions. During the past decade, the combination of single-collision experiments in crossed ion and neutral beams with the velocity map ion imaging detection technique has enabled a wealth of studies on ion-molecule reactions. These methods, in combination with chemical dynamics simulations, have uncovered new and unexpected reaction mechanisms, such as the roundabout mechanism and the subtle influence of the leaving group in anion-molecule nucleophilic substitution reactions. For this important class of reactions, as well as for many fundamental cation-molecule reactions, the information obtained with crossed-beam imaging is discussed. The first steps toward understanding micro-solvation of ion-molecule reaction dynamics are presented. We conclude with the presentation of several interesting directions for future research.

  14. Hexagonal boron nitride nanosheets as a multifunctional background-free matrix to detect small molecules and complicated samples by MALDI mass spectrometry.

    Science.gov (United States)

    Wang, Jianing; Sun, Jie; Wang, Jiyun; Liu, Huihui; Xue, Jinjuan; Nie, Zongxiu

    2017-07-18

    Here we report the innovation of using hexagonal boron nitride (h-BN) nanosheets as the first background-free matrix among the full laser pulse energy range for the analysis and imaging of small molecule metabolites and as an adsorbent for the enrichment of samples. Due to its totally free background and high efficiency as an adsorbent and matrix, h-BN has promising prospects in metabolomics, MALDI imaging, and environmental analysis.

  15. Magnetic Resonance Imaging of Neurotransmitter-Related Molecules.

    Science.gov (United States)

    Igarashi, Hironaka; Ueki, Satoshi; Ohno, Ken; Ohkubo, Masaki; Suzuki, Yuji

    2017-01-01

    Molecular imaging implies the method capable of pictorially displaying distribution of target molecules and their relative concentration in space. In clinical medicine, where non-invasiveness is mandatory, diagnostic molecular imaging has been considered virtually identical to positron emission tomography (PET). However, there is another powerful, apparently underutilized molecular imaging, namely, proton magnetic resonance spectroscopic imaging ( 1 H-MRSI). The technique can detect target molecules endogenous in brain in virtue of their own specific resonance frequencies (chemical shift) and can create quantitative images of each molecule. 1 H-MRSI is conventionally utilized for imaging relatively easily detectable molecules such as N-acetyl-aspartate or lactate. More recently, however, the method is extended into imaging of more challenging molecules such as glutamate or γ-aminobutyric acid (GABA). In this small review, we summarize basic concept of 1 H-MRSI and introduce an advanced technique, i.e. chemical exchange saturation transfer magnetic resonance imaging (CEST MRI), which made realistic glutamate imaging in vivo possible.

  16. Scientists Discover Sugar in Space

    Science.gov (United States)

    2000-06-01

    The prospects for life in the Universe just got sweeter, with the first discovery of a simple sugar molecule in space. The discovery of the sugar molecule glycolaldehyde in a giant cloud of gas and dust near the center of our own Milky Way Galaxy was made by scientists using the National Science Foundation's 12 Meter Telescope, a radio telescope on Kitt Peak, Arizona. "The discovery of this sugar molecule in a cloud from which new stars are forming means it is increasingly likely that the chemical precursors to life are formed in such clouds long before planets develop around the stars," said Jan M. Hollis of the NASA Goddard Space Flight Center in Greenbelt, MD. Hollis worked with Frank J. Lovas of the University of Illinois and Philip R. Jewell of the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, on the observations, made in May. The scientists have submitted their results to the Astrophysical Journal Letters. "This discovery may be an important key to understanding the formation of life on the early Earth," said Jewell. Conditions in interstellar clouds may, in some cases, mimic the conditions on the early Earth, so studying the chemistry of interstellar clouds may help scientists understand how bio-molecules formed early in our planet's history. In addition, some scientists have suggested that Earth could have been "seeded" with complex molecules by passing comets, made of material from the interstellar cloud that condensed to form the Solar System. Glycolaldehyde, an 8-atom molecule composed of carbon, oxygen and hydrogen, can combine with other molecules to form the more-complex sugars Ribose and Glucose. Ribose is a building block of nucleic acids such as RNA and DNA, which carry the genetic code of living organisms. Glucose is the sugar found in fruits. Glycolaldehyde contains exactly the same atoms, though in a different molecular structure, as methyl formate and acetic acid, both of which were detected previously in interstellar clouds

  17. Blind and semi-blind ML detection for space-time block-coded OFDM wireless systems

    KAUST Repository

    Zaib, Alam

    2014-01-01

    This paper investigates the joint maximum likelihood (ML) data detection and channel estimation problem for Alamouti space-time block-coded (STBC) orthogonal frequency-division multiplexing (OFDM) wireless systems. The joint ML estimation and data detection is generally considered a hard combinatorial optimization problem. We propose an efficient low-complexity algorithm based on branch-estimate-bound strategy that renders exact joint ML solution. However, the computational complexity of blind algorithm becomes critical at low signal-to-noise ratio (SNR) as the number of OFDM carriers and constellation size are increased especially in multiple-antenna systems. To overcome this problem, a semi-blind algorithm based on a new framework for reducing the complexity is proposed by relying on subcarrier reordering and decoding the carriers with different levels of confidence using a suitable reliability criterion. In addition, it is shown that by utilizing the inherent structure of Alamouti coding, the estimation performance improvement or the complexity reduction can be achieved. The proposed algorithms can reliably track the wireless Rayleigh fading channel without requiring any channel statistics. Simulation results presented against the perfect coherent detection demonstrate the effectiveness of blind and semi-blind algorithms over frequency-selective channels with different fading characteristics.

  18. Detection of Crohn Disease in Patients with Spondyloarthropathy: The SpACE Capsule Study.

    Science.gov (United States)

    Kopylov, Uri; Starr, Michael; Watts, Craig; Dionne, Serge; Girardin, Marc; Seidman, Ernest G

    2018-02-15

    Inflammatory bowel disease (IBD) is generally reported to be associated with spondylarthropathies (SpA) in 5%-15% of cases. Systematic colonoscopic assessment by protocol demonstrated mucosal inflammation characteristic of Crohn disease (CD) in up to one-third of patients with SpA. Video capsule endoscopy (CE) is a superior diagnostic tool to detect small bowel mucosal disease. Our study compared the accuracy of CE to standard colonoscopy for detection of inflammatory bowel lesions in patients with SpA, and to describe predictors of small bowel inflammation (SBI) in this cohort. Prospective cross-sectional study of adult patients followed for SpA. Patients were evaluated by CE and standard colonoscopy with biopsies. SBI was quantified using the Lewis Score. Additional screening tests included fecal calprotectin (FCP), C-reactive protein (CRP), and a diagnostic panel of serologic, inflammatory and genetic tests (SGI). There were 64 patients recruited (53% female, mean age 42 ± 13 yrs). Chronic gastrointestinal (GI) symptoms were present in 57%. CE revealed significant SBI in 27/64 (42.2%), compared to 7/64 (10.9%) by standard colonoscopy (p = 0.035). Elevated FCP was associated with small bowel CD (OR 4.5, 95% CI 1.01-19.9; p = 0.042). No correlation was observed with presence of GI symptoms, CRP, or SGI results. Finding CD led to a change in management in 65.2% of cases. CE uncovered SBI consistent with CD in 42.2% of patients with SpA, with a significant incremental yield over colonoscopy of 31%. FCP levels were significantly correlated with CE results, while GI symptoms and SGI results were poor predictors of SBI.

  19. An atomic model of brome mosaic virus using direct electron detection and real-space optimization

    Science.gov (United States)

    Wang, Zhao; Hryc, Corey F.; Bammes, Benjamin; Afonine, Pavel V.; Jakana, Joanita; Chen, Dong-Hua; Liu, Xiangan; Baker, Matthew L.; Kao, Cheng; Ludtke, Steven J.; Schmid, Michael F.; Adams, Paul D.; Chiu, Wah

    2014-09-01

    Advances in electron cryo-microscopy have enabled structure determination of macromolecules at near-atomic resolution. However, structure determination, even using de novo methods, remains susceptible to model bias and overfitting. Here we describe a complete workflow for data acquisition, image processing, all-atom modelling and validation of brome mosaic virus, an RNA virus. Data were collected with a direct electron detector in integrating mode and an exposure beyond the traditional radiation damage limit. The final density map has a resolution of 3.8 Å as assessed by two independent data sets and maps. We used the map to derive an all-atom model with a newly implemented real-space optimization protocol. The validity of the model was verified by its match with the density map and a previous model from X-ray crystallography, as well as the internal consistency of models from independent maps. This study demonstrates a practical approach to obtain a rigorously validated atomic resolution electron cryo-microscopy structure.

  20. An atomic model of brome mosaic virus using direct electron detection and real-space optimization.

    Science.gov (United States)

    Wang, Zhao; Hryc, Corey F; Bammes, Benjamin; Afonine, Pavel V; Jakana, Joanita; Chen, Dong-Hua; Liu, Xiangan; Baker, Matthew L; Kao, Cheng; Ludtke, Steven J; Schmid, Michael F; Adams, Paul D; Chiu, Wah

    2014-09-04

    Advances in electron cryo-microscopy have enabled structure determination of macromolecules at near-atomic resolution. However, structure determination, even using de novo methods, remains susceptible to model bias and overfitting. Here we describe a complete workflow for data acquisition, image processing, all-atom modelling and validation of brome mosaic virus, an RNA virus. Data were collected with a direct electron detector in integrating mode and an exposure beyond the traditional radiation damage limit. The final density map has a resolution of 3.8 Å as assessed by two independent data sets and maps. We used the map to derive an all-atom model with a newly implemented real-space optimization protocol. The validity of the model was verified by its match with the density map and a previous model from X-ray crystallography, as well as the internal consistency of models from independent maps. This study demonstrates a practical approach to obtain a rigorously validated atomic resolution electron cryo-microscopy structure.

  1. Experimental Study of Collision Detection Schema Used by Pilots During Closely Spaced Parallel Approaches

    Science.gov (United States)

    Pritchett, Amy R.; Hansman, R. John

    1996-01-01

    An experimental flight simulator study was conducted to examine the mental alerting logic and thresholds used by subjects to issue an alert and execute an avoidance maneuver. Subjects flew a series of autopilot landing approaches with traffic on a closely-spaced parallel approach; during some runs, the traffic would deviate towards the subject and the subject was to indicate the point when they recognized the potential traffic conflict, and then indicate a direction of flight for an avoidance maneuver. A variety of subjects, including graduate students, general aviation pilots and airline pilots, were tested. Five traffic displays were evaluated, with a moving map TCAS-type traffic display as a baseline. A side-task created both high and low workload situations. Subjects appeared to use the lateral deviation of the intruder aircraft from its approach path as the criteria for an alert regardless of the display available. However, with displays showing heading and/or trend information, their alerting thresholds were significantly lowered. This type of range-only schema still resulted in many near misses, as a high convergence rate was often established by the time of the subject's alert. Therefore, the properties of the intruder's trajectory had the greatest effect on the resultant near miss rate; no display system reliably caused alerts timely enough for certain collision avoidance. Subjects' performance dropped significantly on a side-task while they analyzed the need for an alert, showing alert generation can be a high workload situation at critical times. No variation was found between subjects with and with out piloting experience. These results suggest the design of automatic alerting systems should take into account the range-type alerting schema used by the human, such that the rationale for the automatic alert should be obvious to, and trusted by, the operator. Although careful display design may help generate pilot/automation trust, issues such as user non

  2. Population distribution of flexible molecules from maximum entropy analysis using different priors as background information: application to the Φ, Ψ-conformational space of the α-(1-->2)-linked mannose disaccharide present in N- and O-linked glycoproteins.

    Science.gov (United States)

    Säwén, Elin; Massad, Tariq; Landersjö, Clas; Damberg, Peter; Widmalm, Göran

    2010-08-21

    The conformational space available to the flexible molecule α-D-Manp-(1-->2)-α-D-Manp-OMe, a model for the α-(1-->2)-linked mannose disaccharide in N- or O-linked glycoproteins, is determined using experimental data and molecular simulation combined with a maximum entropy approach that leads to a converged population distribution utilizing different input information. A database survey of the Protein Data Bank where structures having the constituent disaccharide were retrieved resulted in an ensemble with >200 structures. Subsequent filtering removed erroneous structures and gave the database (DB) ensemble having three classes of mannose-containing compounds, viz., N- and O-linked structures, and ligands to proteins. A molecular dynamics (MD) simulation of the disaccharide revealed a two-state equilibrium with a major and a minor conformational state, i.e., the MD ensemble. These two different conformation ensembles of the disaccharide were compared to measured experimental spectroscopic data for the molecule in water solution. However, neither of the two populations were compatible with experimental data from optical rotation, NMR (1)H,(1)H cross-relaxation rates as well as homo- and heteronuclear (3)J couplings. The conformational distributions were subsequently used as background information to generate priors that were used in a maximum entropy analysis. The resulting posteriors, i.e., the population distributions after the application of the maximum entropy analysis, still showed notable deviations that were not anticipated based on the prior information. Therefore, reparameterization of homo- and heteronuclear Karplus relationships for the glycosidic torsion angles Φ and Ψ were carried out in which the importance of electronegative substituents on the coupling pathway was deemed essential resulting in four derived equations, two (3)J(COCC) and two (3)J(COCH) being different for the Φ and Ψ torsions, respectively. These Karplus relationships are denoted

  3. Extra-Solar Planetary Imager (ESPI) for Space Based Jovian Planetary Detection

    Science.gov (United States)

    Lyon, Rick G.; Melnick, Gary J.; Nisenson, Peter; Papaliolios, Costa; Ridgeway, Steve; Friedman, Edward; Gezari, Dan Y.; Harwit, Martin; Graf, Paul

    2002-01-01

    We report on out Extra-Solar Planetary Imager (ESPI) study for a recent Midex (NASA Medium Class Explorer Mission) proposal. Proposed for ESPI was a 1.5 x 1.5 square meter Jacquinot apodized square aperture telescope. The combination of apodization and a square aperture telescope significantly reduces the diffracted light from a bright central source over much of the telescope focal plane. As a result, observations of very faint astronomical objects next to bright sources with angular separations as small as 0.32 arcseconds become possible. This permits a sensitive search for exo-planets in reflected light. The system is capable of detecting a Jupiter-like planet in a relatively long-period orbit around as many as 160 to 175 stars with a signal-to-noise ratio greater than 5 in observations lasting maximally 100 hours per star. We discuss the effects of wavefront error, mirror speckle, pointing error and signal-to-noise issues, as well as the scalability of our ESPI study with respect to NASA's Terrestrial Planet Finder mission.

  4. Space-Based Detection of Missing Sulfur Dioxide Sources of Global Air Pollution

    Science.gov (United States)

    McLinden, Chris A.; Fioletov, Vitali; Shephard, Mark W.; Krotkov, Nick; Li, Can; Martin, Randall V.; Moran, Michael D.; Joiner, Joanna

    2016-01-01

    Sulfur dioxide is designated a criteria air contaminant (or equivalent) by virtually all developed nations. When released into the atmosphere, sulfur dioxide forms sulfuric acid and fine particulate matter, secondary pollutants that have significant adverse effects on human health, the environment and the economy. The conventional, bottom-up emissions inventories used to assess impacts, however, are often incomplete or outdated, particularly for developing nations that lack comprehensive emission reporting requirements and infrastructure. Here we present a satellite-based, global emission inventory for SO2 that is derived through a simultaneous detection, mapping and emission-quantifying procedure, and thereby independent of conventional information sources. We find that of the 500 or so large sources in our inventory, nearly 40 are not captured in leading conventional inventories. These missing sources are scattered throughout the developing world-over a third are clustered around the Persian Gulf-and add up to 7 to 14 Tg of SO2 yr(exp -1), or roughly 6-12% of the global anthropogenic source. Our estimates of national total emissions are generally in line with conventional numbers, but for some regions, and for SO2 emissions from volcanoes, discrepancies can be as large as a factor of three or more. We anticipate that our inventory will help eliminate gaps in bottom-up inventories, independent of geopolitical borders and source types.

  5. Tumor suppressor molecules and methods of use

    Science.gov (United States)

    Welch, Peter J.; Barber, Jack R.

    2004-09-07

    The invention provides substantially pure tumor suppressor nucleic acid molecules and tumor suppressor polypeptides. The invention also provides hairpin ribozymes and antibodies selective for these tumor suppressor molecules. Also provided are methods of detecting a neoplastic cell in a sample using detectable agents specific for the tumor suppressor nucleic acids and polypeptides.

  6. Novel Approaches to the Diagnosis of Chronic Disorders of Consciousness: Detecting Peripersonal Space by Using Ultrasonics.

    Science.gov (United States)

    Naro, Antonino; Chillura, Antonino; Portaro, Simona; Bramanti, Alessia; De Luca, Rosaria; Bramanti, Placido; Calabrò, Rocco Salvatore

    2018-01-01

    The assessment of behavioral responsiveness in patients suffering from chronic disorders of consciousness (DoC), including Unresponsive Wakefulness Syndrome (UWS) and Minimally Conscious State (MCS), is challenging. Even if a patient is unresponsive, he/she may be covertly aware in reason of a cognitive-motor dissociation, i.e., a preservation of cognitive functions despite a solely reflexive behavioral responsiveness. The approach of an external stimulus to the peripersonal space (PPS) modifies some biological measures (e.g., hand-blink reflex amplitude) to the purpose of defensive responses from threats. Such modulation depends on a top-down control of subcortical neural circuits, which can be explored through changes in cerebral blood flow velocity (CBFV), using functional transcranial Doppler (fTCD) and, thus, gaining useful, indirect information on brain connectivity. These data may be used for the DoC differential diagnosis. We evaluated the changes in CBFV by measuring the pulsatility index (PI) in 21 patients with DoC (10 patients with MCS and 11 with UWS) and 25 healthy controls (HC) during a passive movement and motor imagery (MI) task in which the hand of the subject approached and, then, moved away from the subject's face. In the passive movement task, the PI increased progressively in the HCs when the hand was moved toward the face and, then, it decreased when the hand was removed from the face. The PI increased when the hand was moved toward the face in patients with DoC, but then, it remained high when the hand was removed from the face and up to 30 s after the end of the movement in the patients with MCS (both MCS+ and MCS-) and 1 min in those with UWS, thus differentiating between patients with MCS and UWS. In the MI task, all the HCs, three out of four patients with MCS+, and one out of six patients with MCS- showed an increase-decrease PI change, whereas the remaining patients with MCS and all the patients with UWS showed no PI changes. Even

  7. Novel Approaches to the Diagnosis of Chronic Disorders of Consciousness: Detecting Peripersonal Space by Using Ultrasonics

    Directory of Open Access Journals (Sweden)

    Antonino Naro

    2018-02-01

    Full Text Available The assessment of behavioral responsiveness in patients suffering from chronic disorders of consciousness (DoC, including Unresponsive Wakefulness Syndrome (UWS and Minimally Conscious State (MCS, is challenging. Even if a patient is unresponsive, he/she may be covertly aware in reason of a cognitive-motor dissociation, i.e., a preservation of cognitive functions despite a solely reflexive behavioral responsiveness. The approach of an external stimulus to the peripersonal space (PPS modifies some biological measures (e.g., hand-blink reflex amplitude to the purpose of defensive responses from threats. Such modulation depends on a top-down control of subcortical neural circuits, which can be explored through changes in cerebral blood flow velocity (CBFV, using functional transcranial Doppler (fTCD and, thus, gaining useful, indirect information on brain connectivity. These data may be used for the DoC differential diagnosis. We evaluated the changes in CBFV by measuring the pulsatility index (PI in 21 patients with DoC (10 patients with MCS and 11 with UWS and 25 healthy controls (HC during a passive movement and motor imagery (MI task in which the hand of the subject approached and, then, moved away from the subject’s face. In the passive movement task, the PI increased progressively in the HCs when the hand was moved toward the face and, then, it decreased when the hand was removed from the face. The PI increased when the hand was moved toward the face in patients with DoC, but then, it remained high when the hand was removed from the face and up to 30 s after the end of the movement in the patients with MCS (both MCS+ and MCS− and 1 min in those with UWS, thus differentiating between patients with MCS and UWS. In the MI task, all the HCs, three out of four patients with MCS+, and one out of six patients with MCS− showed an increase–decrease PI change, whereas the remaining patients with MCS and all the patients with UWS showed no

  8. Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules

    Science.gov (United States)

    Cordiner, M. A.; Charnley, S. B.; Kisiel, Z.; McGuire, B. A.; Kuan, Y.-J.

    2017-12-01

    The 100 m Robert C. Byrd Green Bank Telescope K-band (KFPA) receiver was used to perform a high-sensitivity search for rotational emission lines from complex organic molecules in the cold interstellar medium toward TMC-1 (cyanopolyyne peak), focussing on the identification of new carbon-chain-bearing species as well as molecules of possible prebiotic relevance. We report a detection of the carbon-chain oxide species HC7O and derive a column density of (7.8+/- 0.9)× {10}11 cm-2. This species is theorized to form as a result of associative electron detachment reactions between oxygen atoms and C7H-, and/or reaction of C6H2 + with CO (followed by dissociative electron recombination). Upper limits are given for the related HC6O, C6O, and C7O molecules. In addition, we obtained the first detections of emission from individual 13C isotopologues of HC7N, and derive abundance ratios HC7N/HCCC13CCCCN = 110 ± 16 and HC7N/HCCCC13CCCN = 96 ± 11, indicative of significant 13C depletion in this species relative to the local interstellar elemental 12C/13C ratio of 60-70. The observed spectral region covered two transitions of HC11N, but emission from this species was not detected, and the corresponding column density upper limit is 7.4× {10}10 {{cm}}-2 (at 95% confidence). This is significantly lower than the value of 2.8× {10}11 {{cm}}-2 previously claimed by Bell et al. and confirms the recent nondetection of HC11N in TMC-1 by Loomis et al. Upper limits were also obtained for the column densities of malononitrile and the nitrogen heterocycles quinoline, isoquinoline, and pyrimidine.

  9. Detecting binary non-return-to-zero data in free-space optical communication systems using FPGAs

    Science.gov (United States)

    Bui, Vy; Tran, Lan; El-Araby, Esam; Namazi, Nader M.

    2014-06-01

    High bandwidth, fast deployment with relatively low cost implementation are some of the important advantages of free space optical (FSO) communications. However, the atmospheric turbulence has a substantial impact on the quality of a laser beam propagating through the atmosphere. A new method was presented in [1] and [2] to perform bit synchronization and detection of binary Non-Return-to-Zero (NRZ) data from a free-space optical (FSO) communication link. It was shown that, when the data is binary NRZ with no modulation, the Haar wavelet transformation can effectively reduce the scintillation noise. In this paper, we leverage and modify the work presented in [1] in order to provide a real-time streaming hardware prototype. The applicability of these concepts will be demonstrated through providing the hardware prototype using one of the state-of-the-art reconfigurable hardware, namely Field Programmable Gate Arrays, and highly productive high-level design tools such as System Generator for DSP from Xilinx.

  10. Detection Performance of Upgraded "Polished Panel" Optical Receiver Concept on the Deep-Space Network's 34 Meter Research Antenna

    Science.gov (United States)

    Vilnrotter, Victor A.

    2012-01-01

    The development and demonstration of a "polished panel" optical receiver concept on the 34 meter research antenna of the Deep Space Network (DSN) has been the subject of recent papers. This concept would enable simultaneous reception of optical and microwave signals by retaining the original shape of the main reflector for microwave reception, but with the aluminum panels polished to high reflectivity to enable focusing of optical signal energy as well. A test setup has been installed on the DSN's 34 meter research antenna at Deep Space Station 13 (DSS-13) of NASA's Goldstone Communications Complex in California, and preliminary experimental results have been obtained. This paper describes the results of our latest efforts to improve the point-spread function (PSF) generated by a custom polished panel, in an attempt to reduce the dimensions of the PSF, thus enabling more precise tracking and improved detection performance. The design of the new mechanical support structure and its operation are described, and the results quantified in terms of improvements in collected signal energy and optical communications performance, based on data obtained while tracking the planet Jupiter with the 34 meter research antenna at DSS-13.

  11. Detection of changes in cerebrospinal fluid space in idiopathic normal pressure hydrocephalus using voxel-based morphometry

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, Fumio; Asada, Takashi [University of Tsukuba, Clinical Neuroscience, Medical Sciences for Control of Pathological Process, Graduate School of Comprehensive Human Sciences, Tsukuba-shi, Ibaraki-ken (Japan); Sasaki, Makoto; Kudo, Kohsuke [Iwate Medical University, Advanced Medical Research Center, Morioka (Japan); Takahashi, Satoshi; Narumi, Shinsuke; Terayama, Yasuo [Iwate Medical University, Department of Neurology, Morioka (Japan); Matsuda, Hiroshi [Saitama Medical University International Medical Center, Department of Nuclear Medicine, Saitama (Japan)

    2010-05-15

    We attempted to detect alterations in the cerebrospinal fluid (CSF) space in patients with idiopathic normal pressure hydrocephalus (iNPH) using voxel-based morphometry (VBM). We obtained sagittal volume images of the entire head by three-dimensional T1-weighted magnetic resonance imaging and compared the regional distribution of CSF in 12 patients with iNPH, 14 patients with Alzheimer's disease (AD), and 17 healthy individuals using VBM with automatically extracted CSF objects. VBM demonstrated significant widening at the lateral ventricles and Sylvian fissures and narrowing of the CSF space at the high convexity/midline areas in iNPH patients, compared to the AD patients and healthy controls (p<0.05, after correction with a false-discovery rate). In addition, the ratio of the CSF volume in the lateral ventricle/Sylvian fissure area to that in the high convexity/midline area in iNPH patients (3.9{+-}1.2) was remarkably greater than that in AD patients (1.2{+-}0.3) and controls (0.9{+-}0.3; one-way ANOVA, p <0.001; post hoc Tukey's test, p < 0.001); we could discriminate iNPH patients from those in the other two groups without any overlap, when using a cutoff level of 1.9. VBM using CSF objects can be used to delineate the characteristic alteration of the CSF space in iNPH patients, which has been evaluated by visual interpretation. (orig.)

  12. A novel weld seam detection method for space weld seam of narrow butt joint in laser welding

    Science.gov (United States)

    Shao, Wen Jun; Huang, Yu; Zhang, Yong

    2018-02-01

    Structured light measurement is widely used for weld seam detection owing to its high measurement precision and robust. However, there is nearly no geometrical deformation of the stripe projected onto weld face, whose seam width is less than 0.1 mm and without misalignment. So, it's very difficult to ensure an exact retrieval of the seam feature. This issue is raised as laser welding for butt joint of thin metal plate is widely applied. Moreover, measurement for the seam width, seam center and the normal vector of the weld face at the same time during welding process is of great importance to the welding quality but rarely reported. Consequently, a seam measurement method based on vision sensor for space weld seam of narrow butt joint is proposed in this article. Three laser stripes with different wave length are project on the weldment, in which two red laser stripes are designed and used to measure the three dimensional profile of the weld face by the principle of optical triangulation, and the third green laser stripe is used as light source to measure the edge and the centerline of the seam by the principle of passive vision sensor. The corresponding image process algorithm is proposed to extract the centerline of the red laser stripes as well as the seam feature. All these three laser stripes are captured and processed in a single image so that the three dimensional position of the space weld seam can be obtained simultaneously. Finally, the result of experiment reveals that the proposed method can meet the precision demand of space narrow butt joint.

  13. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Molecule Matters van der Waals Molecules - Rg•••HF Complexes are Debye Molecules! E Arunan. Feature Article Volume 15 Issue 7 July 2010 pp 667-674. Fulltext. Click here to view fulltext PDF. Permanent link:

  14. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 12. Molecule Matters van der Waals Molecules - Noble Gas Clusters are London Molecules! E Arunan ... Author Affiliations. E Arunan1. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  15. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Molecule Matters van der Waals Molecules - Rg•••HF Complexes are Debye Molecules! E Arunan ... Author Affiliations. E Arunan1. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  16. Development of Eddy Current Technique for the Detection of Stress Corrosion Cracking in Space Shuttle Primary Reaction Control Thrusters

    Science.gov (United States)

    Wincheski, Buzz; Simpson, John; Koshti, Ajay

    2006-01-01

    A recent identification of stress corrosion cracking in the Space Shuttle Primary Reaction Control System (PRCS) thrusters triggered an extensive nondestructive evaluation effort to develop techniques capable of identifying such damage on installed shuttle hardware. As a part of this effort, specially designed eddy current probes inserted into the acoustic cavity were explored for the detection of such flaws and for evaluation of the remaining material between the crack tip and acoustic cavity. The technique utilizes two orthogonal eddy current probes which are scanned under stepper motor control in the acoustic cavity to identify cracks hidden with as much as 0.060 remaining wall thickness to the cavity. As crack growth rates in this area have been determined to be very slow, such an inspection provides a large safety margin for continued operation of the critical shuttle hardware. Testing has been performed on thruster components with both actual and fabricated defects. This paper will review the design and performance of the developed eddy current inspection system. Detection of flaws as a function of remaining wall thickness will be presented along with the proposed system configuration for depot level or on-vehicle inspection capabilities.

  17. Space space space

    CERN Document Server

    Trembach, Vera

    2014-01-01

    Space is an introduction to the mysteries of the Universe. Included are Task Cards for independent learning, Journal Word Cards for creative writing, and Hands-On Activities for reinforcing skills in Math and Language Arts. Space is a perfect introduction to further research of the Solar System.

  18. Caliste 64: detection unit of a spectro imager array for a hard x-ray space telescope

    Science.gov (United States)

    Limousin, O.; Meuris, A.; Lugiez, F.; Gevin, Olivier; Pinsard, F.; Blondel, C.; Le Mer, I.; Delagnes, E.; Vassal, M. C.; Soufflet, F.; Bocage, R.; Penquer, A.; Billot, M.

    2017-11-01

    In the frame of the hard X-ray Simbol-X observatory, a joint CNES-ASI space mission to be flown in 2014, a prototype of miniature Cd(Zn)Te camera equipped with 64 pixels has been designed. The device, called Caliste 64, is a spectro-imager with high resolution event timetagging capability. Caliste 64 integrates a Cd(Zn)Te semiconductor detector with segmented electrode and its front-end electronics made of 64 independent analog readout channels. This 1 × 1 × 2 cm3 camera, able to detect photons in the range from 2 keV up to 250 keV, is an elementary detection unit juxtaposable on its four sides. Consequently, large detector array can be made assembling a mosaic of Caliste 64 units. Electronics readout module is achieved by stacking four IDeF-X V1.1 ASICs, perpendicular to the detection plane. We achieved good noise performances, with a mean Equivalent Noise Charge of 65 electrons rms over the 64 channels. For the first prototypes, we chose Pt//CdTe//Al/Ti/Au Schottky detectors because of their very low dark current and excellent spectroscopic performances. Recently a Caliste 64 prototype has been also equipped with a 2 mm thick Au//CdZnTe//Au detector. This paper presents the performances of these four prototypes and demonstrates spectral performances better than 1 keV fwhm at 59.54 keV when the samples are moderately cooled down to -10°C.

  19. Sequence space coverage, entropy of genomes and the potential to detect non-human DNA in human samples

    Directory of Open Access Journals (Sweden)

    Maley Carlo C

    2008-10-01

    Full Text Available Abstract Background Genomes store information for building and maintaining organisms. Complete sequencing of many genomes provides the opportunity to study and compare global information properties of those genomes. Results We have analyzed aspects of the information content of Homo sapiens, Mus musculus, Drosophila melanogaster, Caenorhabditis elegans, Arabidopsis thaliana, Saccharomyces cerevisiae, and Escherichia coli (K-12 genomes. Virtually all possible (> 98% 12 bp oligomers appear in vertebrate genomes while 98% to D. melanogaster (12–17 bp, C. elegans (11–17 bp, A. thaliana (11–17 bp, S. cerevisiae (10–16 bp and E. coli (9–15 bp. Frequencies of unique oligomers in the genomes follow similar patterns. We identified a set of 2.6 M 15-mers that are more than 1 nucleotide different from all 15-mers in the human genome and so could be used as probes to detect microbes in human samples. In a human sample, these probes would detect 100% of the 433 currently fully sequenced prokaryotes and 75% of the 3065 fully sequenced viruses. The human genome is significantly more compact in sequence space than a random genome. We identified the most frequent 5- to 20-mers in the human genome, which may prove useful as PCR primers. We also identified a bacterium, Anaeromyxobacter dehalogenans, which has an exceptionally low diversity of oligomers given the size of its genome and its GC content. The entropy of coding regions in the human genome is significantly higher than non-coding regions and chromosomes. However chromosomes 1, 2, 9, 12 and 14 have a relatively high proportion of coding DNA without high entropy, and chromosome 20 is the opposite with a low frequency of coding regions but relatively high entropy. Conclusion Measures of the frequency of oligomers are useful for designing PCR assays and for identifying chromosomes and organisms with hidden structure that had not been previously recognized. This information may be used to detect

  20. Feature-space assessment of electrical impedance tomography coregistered with computed tomography in detecting multiple contrast targets

    International Nuclear Information System (INIS)

    Krishnan, Kalpagam; Liu, Jeff; Kohli, Kirpal

    2014-01-01

    Purpose: Fusion of electrical impedance tomography (EIT) with computed tomography (CT) can be useful as a clinical tool for providing additional physiological information about tissues, but requires suitable fusion algorithms and validation procedures. This work explores the feasibility of fusing EIT and CT images using an algorithm for coregistration. The imaging performance is validated through feature space assessment on phantom contrast targets. Methods: EIT data were acquired by scanning a phantom using a circuit, configured for injecting current through 16 electrodes, placed around the phantom. A conductivity image of the phantom was obtained from the data using electrical impedance and diffuse optical tomography reconstruction software (EIDORS). A CT image of the phantom was also acquired. The EIT and CT images were fused using a region of interest (ROI) coregistration fusion algorithm. Phantom imaging experiments were carried out on objects of different contrasts, sizes, and positions. The conductive medium of the phantoms was made of a tissue-mimicking bolus material that is routinely used in clinical radiation therapy settings. To validate the imaging performance in detecting different contrasts, the ROI of the phantom was filled with distilled water and normal saline. Spatially separated cylindrical objects of different sizes were used for validating the imaging performance in multiple target detection. Analyses of the CT, EIT and the EIT/CT phantom images were carried out based on the variations of contrast, correlation, energy, and homogeneity, using a gray level co-occurrence matrix (GLCM). A reference image of the phantom was simulated using EIDORS, and the performances of the CT and EIT imaging systems were evaluated and compared against the performance of the EIT/CT system using various feature metrics, detectability, and structural similarity index measures. Results: In detecting distilled and normal saline water in bolus medium, EIT as a stand

  1. Fluorescence spectroscopy of single molecules at room temperature and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Taekjip [Univ. of California, Berkeley, CA (United States)

    1996-12-01

    We performed fluorescence spectroscopy of single and pairs of dye molecules on a surface at room temperature. Near field scanning optical microscope (NSOM) and far field scanning optical microscope with multi-color excitation/detection capability were built. The instrument is capable of optical imaging with 100nm resolution and has the sensitivity necessary for single molecule detection. A variety of dynamic events which cannot be observed from an ensemble of molecules is revealed when the molecules are probed one at a time. They include (1) spectral jumps correlated with dark states, (2) individually resolved quantum jumps to and from the meta-stable triplet state, (3) rotational jumps due to desorption/readsorption events of single molecules on the surface. For these studies, a computer controlled optical system which automatically and rapidly locates and performs spectroscopic measurements on single molecules was developed. We also studied the interaction between closely spaced pairs of molecules. In particular, fluorescence resonance energy transfer between a single resonant pair of donor and acceptor molecules was measured. Photodestruction dynamics of the donor or acceptor were used to determine the presence and efficiency of energy transfer Dual molecule spectroscopy was extended to a non-resonant pair of molecules to obtain high resolution differential distance information. By combining NSOM and dual color scheme, we studied the co-localization of parasite proteins and host proteins on a human red blood cell membrane infected with malaria. These dual-molecule techniques can be used to measure distances, relative orientations, and changes in distances/orientations of biological macromolecules with very good spatial, angular and temporal resolutions, hence opening new capabilities in the study of such systems.

  2. Expression of the C- KIT Molecule in Acute Myeloid Leukemias: Implications of the Immuno phenotypes CD117 and CD15 in the Detection of Minimal Residual Disease

    International Nuclear Information System (INIS)

    Omar, S.

    2001-01-01

    Study of the c-kit proto-oncogene (CD117) may be of help for the identification of phenotypic profiles that are absent or present at very low frequencies on normal human blast cells and therefore might be of great value for the detection of leukemic cells displaying such immuno phenotypes in patients in complete remission. Design and methods: Ninety patients with acute myeloid leukemias, diagnosed according to FAB criteria and immunological marker studies, were studied for the dual expression on blast cells of the CD117/CD15 immuno phenotype co expression by direct immunofluorescence assay using dual staining combination flow cytometry. Results: In 69/90 acute myeloid leukemia patients analyzed (77%), blast cells expressed the CD117 antigen. Moreover, in 38 of them (42% of acute myeloid leukemia cases), leukemic blasts co expressed the CD117 and CD15 antigens. There was no significant correlation between the FAB classification and the CD117 and CD15 expression in acute myeloid leukemia cases. Conclusions: These results suggest that immunological methods for the detection of MRD based on the existence of aberrant phenotypes could be used in the majority of AML patients. This phenotype CD117/CD15, present in acute myeloid leukemia cases at a relatively high frequency (42%), represents an aberrant phenotype, because it was not detected on normal human blast cells, suggesting that the use of these combinations of monoclonal antibodies could be of help in detecting residual leukemic blasts among normal blast cells. The use of the CD117 antigen in different monoclonal antibodies combinations may be of great help for the detection of minimal residual disease in a high proportion of acute myeloid leukemia cases, especially in those patients displaying the CD117+/CD15+ immuno phenotype, because cells co expressing both antigens in normal blasts, if present, are at very low frequencies. The simultaneous assessment of two or more markers in single cells has facilitated the

  3. A cell-based MHC stabilization assay for the detection of peptide binding to the canine classical class I molecule, DLA-88.

    Science.gov (United States)

    Ross, Peter; Holmes, Jennifer C; Gojanovich, Gregory S; Hess, Paul R

    2012-12-15

    Identifying immunodominant CTL epitopes is essential for studying CD8+ T-cell responses in populations, but remains difficult, as peptides within antigens typically are too numerous for all to be synthesized and screened. Instead, to facilitate discovery, in silico scanning of proteins for sequences that match the motif, or binding preferences, of the restricting MHC class I allele - the largest determinant of immunodominance - can be used to predict likely candidates. The high false positive rate with this analysis ideally requires binding confirmation, which is obtained routinely by an assay using cell lines such as RMA-S that have defective transporter associated with antigen processing (TAP) machinery, and consequently, few surface class I molecules. The stabilization and resultant increased life-span of peptide-MHC complexes on the cell surface by the addition of true binders validates their identity. To determine whether a similar assay could be developed for dogs, we transfected a prevalent class I allele, DLA-88*50801, into RMA-S. In the BARC3 clone, the recombinant heavy chain was associated with murine β2-microglobulin, and importantly, could differentiate motif-matched and -mismatched peptides by surface MHC stabilization. This work demonstrates the potential to use RMA-S cells transfected with canine alleles as a tool for CTL epitope discovery in this species. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Epidemiological analysis, detection, and comparison of space-time patterns of Beijing hand-foot-mouth disease (2008-2012.

    Directory of Open Access Journals (Sweden)

    Jiaojiao Wang

    Full Text Available BACKGROUND: Hand, foot, and mouth disease (HFMD mostly affects the health of infants and preschool children. Many studies of HFMD in different regions have been published. However, the epidemiological characteristics and space-time patterns of individual-level HFMD cases in a major city such as Beijing are unknown. The objective of this study was to investigate epidemiological features and identify high relative risk space-time HFMD clusters at a fine spatial scale. METHODS: Detailed information on age, occupation, pathogen and gender was used to analyze the epidemiological features of HFMD epidemics. Data on individual-level HFMD cases were examined using Local Indicators of Spatial Association (LISA analysis to identify the spatial autocorrelation of HFMD incidence. Spatial filtering combined with scan statistics methods were used to detect HFMD clusters. RESULTS: A total of 157,707 HFMD cases (60.25% were male, 39.75% were female reported in Beijing from 2008 to 2012 included 1465 severe cases and 33 fatal cases. The annual average incidence rate was 164.3 per 100,000 (ranged from 104.2 in 2008 to 231.5 in 2010. Male incidence was higher than female incidence for the 0 to 14-year age group, and 93.88% were nursery children or lived at home. Areas at a higher relative risk were mainly located in the urban-rural transition zones (the percentage of the population at risk ranged from 33.89% in 2011 to 39.58% in 2012 showing High-High positive spatial association for HFMD incidence. The most likely space-time cluster was located in the mid-east part of the Fangshan district, southwest of Beijing. CONCLUSIONS: The spatial-time patterns of Beijing HFMD (2008-2012 showed relatively steady. The population at risk were mainly distributed in the urban-rural transition zones. Epidemiological features of Beijing HFMD were generally consistent with the previous research. The findings generated computational insights useful for disease surveillance, risk

  5. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    RESONANCE. February 2015. GENERAL ARTICLE. Single-Molecule Spectroscopy. Every Molecule is Different! Kankan Bhattacharyya. Keywords. Single-molecule ..... Resonance Energy. Transfer (FRET) is an elegant technique to measure the distance between a donor and an acceptor molecule. FRET refers to the.

  6. Molecule of the Month.

    Indian Academy of Sciences (India)

    Molecule of the Month. Corannulene - A Bucky Bowl. H Surya Prakash Rao. The structure, properties and synthesis of a bowl shaped molecule, which resembles a fragment of fullerene, are described here. Chemistry of aromatic molecules has a long history. Many molecules made up of multiple benzene-like rings have ...

  7. Online platform for applying space-time scan statistics for prospectively detecting emerging hot spots of dengue fever.

    Science.gov (United States)

    Chen, Chien-Chou; Teng, Yung-Chu; Lin, Bo-Cheng; Fan, I-Chun; Chan, Ta-Chien

    2016-11-25

    Cases of dengue fever have increased in areas of Southeast Asia in recent years. Taiwan hit a record-high 42,856 cases in 2015, with the majority in southern Tainan and Kaohsiung Cities. Leveraging spatial statistics and geo-visualization techniques, we aim to design an online analytical tool for local public health workers to prospectively identify ongoing hot spots of dengue fever weekly at the village level. A total of 57,516 confirmed cases of dengue fever in 2014 and 2015 were obtained from the Taiwan Centers for Disease Control (TCDC). Incorporating demographic information as covariates with cumulative cases (365 days) in a discrete Poisson model, we iteratively applied space-time scan statistics by SaTScan software to detect the currently active cluster of dengue fever (reported as relative risk) in each village of Tainan and Kaohsiung every week. A village with a relative risk >1 and p value dengue fever transmission on a weekly basis at the village level by using the routine surveillance data.

  8. Millimeter Wave Detection of Localized Anomalies in the Space Shuttle External Fuel Tank Insulating Foam and Acreage Heat Tiles

    Science.gov (United States)

    Kharkovsky, S.; Case, J. T.; Zoughi, R.; Hepburn, F.

    2005-01-01

    The Space Shuttle Columbia's catastrophic accident emphasizes the growing need for developing and applying effective, robust and life-cycle oriented nondestructive testing (NDT) methods for inspecting the shuttle external fuel tank spray on foam insulation (SOFI) and its protective acreage heat tiles. Millimeter wave NDT techniques were one of the methods chosen for evaluating their potential for inspecting these structures. Several panels with embedded anomalies (mainly voids) were produced and tested for this purpose. Near-field and far-field millimeter wave NDT methods were used for producing millimeter wave images of the anomalies in SOFI panel and heat tiles. This paper presents the results of an investigation for the purpose of detecting localized anomalies in two SOFI panels and a set of heat tiles. To this end, reflectometers at a relatively wide range of frequencies (Ka-band (26.5 - 40 GHz) to W-band (75 - 110 GHz)) and utilizing different types of radiators were employed. The results clearly illustrate the utility of these methods for this purpose.

  9. Automatic detection of microaneurysms in diabetic retinopathy fundus images using the L*a*b color space.

    Science.gov (United States)

    Navarro, Pedro J; Alonso, Diego; Stathis, Kostas

    2016-01-01

    We develop an automated image processing system for detecting microaneurysm (MA) in diabetic patients. Diabetic retinopathy is one of the main causes of preventable blindness in working age diabetic people with the presence of an MA being one of the first signs. We transform the eye fundus images to the L*a*b* color space in order to separately process the L* and a* channels, looking for MAs in each of them. We then fuse the results, and last send the MA candidates to a k-nearest neighbors classifier for final assessment. The performance of the method, measured against 50 images with an ophthalmologist's hand-drawn ground-truth, shows high sensitivity (100%) and accuracy (84%), and running times around 10 s. This kind of automatic image processing application is important in order to reduce the burden on the public health system associated with the diagnosis of diabetic retinopathy given the high number of potential patients that need periodic screening.

  10. Present status of the 4-m ILMT data reduction pipeline: application to space debris detection and characterization

    Science.gov (United States)

    Pradhan, Bikram; Delchambre, Ludovic; Hickson, Paul; Akhunov, Talat; Bartczak, Przemyslaw; Kumar, Brajesh; Surdej, Jean

    2018-04-01

    The 4-m International Liquid Mirror Telescope (ILMT) located at the ARIES Observatory (Devasthal, India) has been designed to scan at a latitude of +29° 22' 26" a band of sky having a width of about half a degree in the Time Delayed Integration (TDI) mode. Therefore, a special data-reduction and analysis pipeline to process online the large amount of optical data being produced has been dedicated to it. This requirement has led to the development of the 4-m ILMT data reduction pipeline, a new software package built with Python in order to simplify a large number of tasks aimed at the reduction of the acquired TDI images. This software provides astronomers with specially designed data reduction functions, astrometry and photometry calibration tools. In this paper we discuss the various reduction and calibration steps followed to reduce TDI images obtained in May 2015 with the Devasthal 1.3m telescope. We report here the detection and characterization of nine space debris present in the TDI frames.

  11. Detection of pigments of halophilic endoliths from gypsum: Raman portable instrument and European Space Agency's prototype analysis.

    Science.gov (United States)

    Culka, Adam; Osterrothová, Kateřina; Hutchinson, Ian; Ingley, Richard; McHugh, Melissa; Oren, Aharon; Edwards, Howell G M; Jehlička, Jan

    2014-12-13

    A prototype instrument, under development at the University of Leicester, for the future European Space Agency (ESA) ExoMars mission, was used for the analysis of microbial pigments within a stratified gypsum crust from a hypersaline saltern evaporation pond at Eilat (Israel). Additionally, the same samples were analysed using a miniaturized Raman spectrometer, featuring the same 532 nm excitation. The differences in the position of the specific bands, attributed to carotenoid pigments from different coloured layers, were minor when analysed by the ESA prototype instrument; therefore, making it difficult to distinguish among the different pigments. The portable Delta Nu Advantage instrument allowed for the discrimination of microbial carotenoids from the orange/green and purple layers. The purpose of this study was to complement previous laboratory results with new data and experience with portable or handheld Raman systems, even with a dedicated prototype Raman system for the exploration of Mars. The latter is equipped with an excitation wavelength falling within the carotenoid polyene resonance region. The ESA prototype Raman instrument detected the carotenoid pigments (biomarkers) with ease, although further detailed distinctions among them were not achieved. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  12. A Selective Assay to Detect Chitin and Biologically Active Nano-Machineries for Chitin-Biosynthesis with Their Intrinsic Chitin-Synthase Molecules

    OpenAIRE

    Herasimenka, Yury; Kotasinska, Marta; Walter, Stefan; Schrempf, Hildgund

    2010-01-01

    A new assay system for chitin has been developed. It comprises the chitin-binding protein ChbB in fusion with a His-tag as well as with a Strep-tag, the latter of which was chemically coupled to horseradish peroxidase. With the resulting complex, minimal quantities of chitin are photometrically detectable. In addition, the assay allows rapid scoring of the activity of chitin-synthases. As a result, a refined procedure for the rapid purification of yeast chitosomes (nano-machineries for chitin...

  13. Single-molecule analysis of lead(II)-binding aptamer conformational changes in an α-hemolysin nanopore, and sensitive detection of lead(II)

    International Nuclear Information System (INIS)

    Wang, Hai-Yan; Song, Ze-Yang; Zhang, Hui-Sheng; Chen, Si-Ping

    2016-01-01

    The α-hemolysin (αHL) nanopore is capable of analyzing DNA duplex and DNA aptamer as they can be electrophoretically driven into the vestibule from the cis entrance. The current study describes the competitive interaction induced by Pb 2+ that changes the secondary structure of DNA duplex in asymmetrical electrolyte solution. DNA duplex formed by the partial complementary DNA and DNA aptamer sequence produced unzipping blockages with the dwell unzipping time lasting 2.84 ± 0.7 ms. By cation-DNA interaction with Pb 2+ , the DNA duplex will unwind and then form Pb 2+ -stabilized-DNA aptamer, which will be captured and unfolded in vestibule. The pore conductance were reduced to 54 % and 94 % with mean dwell unfolding times of 165 ± 12 ms. The competitive behavior between Pb 2+ and single-strand DNA was further utilized to detect Pb 2+ in solution with a detection limit of 0.5 nM. This nanopore platform also provides a powerful tool for studying the cation-DNA interactions in DNA aptamer conformational changes. Thus, the results drawn from these studies provide insights into the applications of α-hemolysin nanopore as a molecular sieve to different DNA secondary structure in future application of nanopore analysis. (author)

  14. Space experiment "Rad Gene"-report 2; Detection of DNA damage and adaptive response activity of human cells exposed to space radiations

    Science.gov (United States)

    Ohnishi, Takeo; Takahashi, Akihisa; Su, Xiaoming; Suzuki, Masao; Tsuruoka, Chizuru; Suzuki, Hiromi; Shimazu, Toru; Seki, Masaya; Hashizume, Toko; Nagamatsu, Aiko; Omori, Katsunori; Ishioka, Noriaki

    To identify DNA damage induced by space radiations such as the high linear energy transfer (LET) particles, phospho-H2AX (γH2AX) foci formation was analyzed in human cells frozen in an International Space Station (ISS) freezer for 133 days. After recovering the frozen sample to the earth, the cells were cultured for 30 min, and then fixed. Here, we show a track of γH2AX positive foci in them by immuno-cytochemical methods. It is suggested that space radiations, especially high LET particles, induced DSBs as a track. From the formation of the tracks in nuclei, exposure dose rate was calculated to be 0.7 mSv per day as relatively high-energy space radiations of Fe-ions (500 MeV/u, 200 keV/µm). From the physical dosimetry with CR-39 and TLD, dose rate was 0.5 mSv per day. These values were similar between biological and physical dosimetries. In addition, the aim of this study was to clarify the effect of space radiations on the radio-adaptive response. After the frozen samples were returned to earth, the cells were cultured for 6 h, and then exposed to challenging X-irradiation doses of 1.2 Gy or 2 Gy. Cellular sensitivity, apoptosis, chromosome aberrations and mutation frequencies were scored. In the cells exposed to a space environment, all of radio-adaptive responses such as the induction of radio-resistance and the depression of radiation-induced apoptosis, chromosome aberrations and mutant frequencies investigated here were found in wtp53 cells, but not in the mp53 cells. These results confirmed that the cells exposed to a space environment were likely to the exposed cells to radiation by the specific low dose range (window; 20-100 mSv) which can lead to an adaptive response on ground-base experiments, and that the cells indicated the biological effects from the space-radiation exposure with such low doses in space.

  15. Single-Molecule Plasmon Sensing: Current Status and Future Prospects.

    Science.gov (United States)

    Taylor, Adam B; Zijlstra, Peter

    2017-08-25

    Single-molecule detection has long relied on fluorescent labeling with high quantum-yield fluorophores. Plasmon-enhanced detection circumvents the need for labeling by allowing direct optical detection of weakly emitting and completely nonfluorescent species. This review focuses on recent advances in single molecule detection using plasmonic metal nanostructures as a sensing platform, particularly using a single particle-single molecule approach. In the past decade two mechanisms for plasmon-enhanced single-molecule detection have been demonstrated: (1) by plasmonically enhancing the emission of weakly fluorescent biomolecules, or (2) by monitoring shifts of the plasmon resonance induced by single-molecule interactions. We begin with a motivation regarding the importance of single molecule detection, and advantages plasmonic detection offers. We describe both detection mechanisms and discuss challenges and potential solutions. We finalize by highlighting the exciting possibilities in analytical chemistry and medical diagnostics.

  16. Influence of the atmosphere on the space detection of ultra-high energy cosmic rays; Influence de l'atmosphere sur la detection spatiale des rayons cosmiques d'ultra-haute energie

    Energy Technology Data Exchange (ETDEWEB)

    Moreggia, S

    2007-06-15

    EUSO (Extreme Universe Space Observatory) is a project of ultra-high energy (> 10{sup 20} eV) cosmic rays detection from space. Its concept relies on the observation of fluorescence and Cerenkov photons emitted by extensive air showers from a telescope located on the International Space Station. A simulation software has been developed to study the characteristics of this innovative concept of detection. It deals with the different steps of the detection chain: extensive air shower development, emission of fluorescence and Cerenkov light, and radiative transfer to the telescope. A Monte-Carlo code has been implemented to simulate the propagation of photons through the atmosphere, dealing with multiple scattering in clear sky conditions as well as in presence of aerosols and clouds. With this simulation program, the impact of atmospheric conditions on the performance of a space-located detector has been studied. The precise treatment of photons propagation through the atmosphere has permitted to quantify the scattered light contribution to the detected signal. (author)

  17. The role of MEXART in the National Space Weather Laboratory of Mexico: Detection of solar wind, CMEs, ionosphere, active regions and flares.

    Science.gov (United States)

    Mejia-Ambriz, J.; Gonzalez-Esparza, A.; De la Luz, V.; Villanueva-Hernandez, P.; Andrade, E.; Aguilar-Rodriguez, E.; Chang, O.; Romero Hernandez, E.; Sergeeva, M. A.; Perez Alanis, C. A.; Reyes-Marin, P. A.

    2017-12-01

    The National Space Weather Laboratory - Laboratorio Nacional de Clima Espacial (LANCE) - of Mexico has different ground based instruments to study and monitor the space weather. One of these instruments is the Mexican Array Radio Telescope (MEXART) which is principally dedicated to remote sensing the solar wind and coronal mass ejections (CMEs) at 140 MHz, the instrument can detect solar wind densities and speeds from about 0.4 to 1 AU by modeling observations of interplanetary scintillation (IPS). MEXART is also able to detect ionospheric disturbances associated with transient space weather events by the analysis of ionospheric scintillation (IONS) . Additionally, MEXART has followed the Sun since the beginning of the current Solar Cycle 24 with records of 8 minutes per day, and occasionally, has partially detected the process of strong solar flares. Here we show the contributions of MEXART to the LANCE by reporting recent detections of CMEs by IPS, the arrive of transient events at Earth by IONS, the influence of active regions in the flux of the Sun at 140 MHz and the detection of a M6.5 class flare. Furthermore we report the status of a near real time analysis of IPS data for forecast purposes and the potential contribution to the Worldwide IPS Stations network (WIPSS), which is an effort to achieve a better coverage of the solar wind observations in the inner heliosphere.

  18. The status of molecules

    International Nuclear Information System (INIS)

    Barnes, T.

    1994-01-01

    The experimental and theoretical status of hadronic molecules, which are weakly-bound states of two or more hadrons are summarized. A brief history of the subject is given, and a few good candidates are discussed. Some signatures for molecules which may be of interest in the classification of possible molecule states are studied. It is shown that a more general understanding of 2 → 2 hadron-hadron scattering amplitudes will be crucial for molecule searches. A few more recent molecule candidates which are not well established as molecules but satisfy some of the expected signatures are also discussed. (author). 50 refs

  19. Double photoionisation spectra of molecules

    CERN Document Server

    Eland, John

    2017-01-01

    This book contains spectra of the doubly charged positive ions (dications) of some 75 molecules, including the major constituents of terrestrial and planetary atmospheres and prototypes of major chemical groups. It is intended to be a new resource for research in all areas of molecular spectroscopy involving high energy environments, both terrestrial and extra-terrestrial. All the spectra have been produced by photoionisation using laboratory lamps or synchrotron radiation and have been measured using the magnetic bottle time-of-flight technique by coincidence detection of correlated electron pairs. Full references to published work on the same species are given, though for several molecules these are the first published spectra. Double ionisation energies are listed and discussed in relation to the molecular electronic structure of the molecules. A full introduction to the field of molecular double ionisation is included and the mechanisms by which double photoionisation can occur are examined in detail. A p...

  20. Laboratory simulations of prebiotic molecule stability in the jarosite mineral group; end member evaluation of detection and decomposition behavior related to Mars sample return

    Energy Technology Data Exchange (ETDEWEB)

    J. Michelle Kotler; Nancy W. Hinman; C. Doc Richardson; Andrew G. Conly; Jill R. Scott

    2009-10-01

    Recently, the prebiotic amino acid glycine has been found associated with natural jarosite samples from various locations around the world. Since the discovery of jarosite on Mars, extensive research focuses on linking this mineral group with possible detection of biosignatures in the geologic record on Earth and Mars. Multiple analytical methods, including extraction and mass spectrometry techniques have identified glycine and other biomolecules in jarosite samples. The jarosite end members jarosite (sensu stricto-potassium jarosite), natrojarosite (sodium jarosite), and ammoniojarosite (ammonium jarosite) have different thermodynamic stabilities, decompose at different rates, and have potentially different susceptibilities to substitution. Planetary protection issues have led to the suggestion that samples returned from Mars would need to be heat-treated before they could be analyzed on Earth. Although heat treatment of the samples would in theory destroy any potential biosignatures, valuable information can be obtained during thermal treatment by employing gravimetric techniques. The relationship between the thermodynamic stability of the jarosite end members and the effect that glycine has on the thermal decomposition behavior of each end member was investigated using thermal gravimetric analysis. Thermal gravimetric analysis has been suggested as a method capable of providing the heat treatment necessary to provide planetary protection while still providing useful information about the original state and composition of the potentially returned materials. Introducing glycine into the synthesis procedure of the potassium, sodium and ammonium jarosite end-member has elucidated the effects that glycine has on the thermal stability of the mineral group. Potassium jarosite appears to be the least susceptible to the effects of glycine, with the sodium and ammonium end members showing marked changes in thermal decomposition behavior and decomposition rates. In

  1. CD molecules 2005: human cell differentiation molecules

    Czech Academy of Sciences Publication Activity Database

    Zola, H.; Swart, B.; Nicholson, I.; Aasted, B.; Bensussan, A.; Boumsell, L.; Buckley, C.; Clark, G.; Drbal, Karel; Engel, P.; Hart, D.; Hořejší, Václav; Isacke, C.; Macardle, P.; Malavasi, F.; Mason, D.; Olive, D.; Saalmüller, A.; Schlossman, S.F.; Schwartz-Albiez, R.; Simmons, P.; Tedder, T.F.; Uguccioni, M.; Warren, H.

    2005-01-01

    Roč. 106, č. 9 (2005), s. 3123-3126 ISSN 0006-4971 Institutional research plan: CEZ:AV0Z5052915 Keywords : CD molecules * leukocyte antigen Subject RIV: EC - Immunology Impact factor: 10.131, year: 2005

  2. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    GENERAL ARTICLE. Single-Molecule Spectroscopy. Every Molecule is Different! Kankan Bhattacharyya. Keywords. Single-molecule spectroscopy. (SMS), confocal microscopy,. FCS, sm-FRET, FLIM. 1 High-resolution spectrum re- fers to a spectrum consisting of very sharp lines. The sharp lines clearly display transitions to ...

  3. Radio observations of molecules in the interstellar gas

    International Nuclear Information System (INIS)

    Thaddeus, P.

    1981-01-01

    Most interstellar molecules are familiar stable compounds but nearly one-fifth are ions, radicals and acetylenic carbon chains so reactive in the laboratory that before being detected in space they had rarely been observed or were entirely unknown. The heavy atom backbone of the known interstellar molecules is a linear chain of C,N,O or S; rings and branched chains are missing. The most readily observed spectral lines of most interstellar molecules are rotational transitions at millimetre wavelengths. These are generally excited by H2 collisions. Maser line emission from OH, H2O, SiO and CH3OH-extremely intense, small sources, often polarized and sometimes time-dependent - are examples of nonequilibrium excitation. A number of rare isotopic species, particularly those of C,N and O are observed in interstellar molecules. Isotopic ratios differing from those on Earth by two- or threefold apparently exist, and in all but one case can be attributed to stellar nucleosynthesis since the formation of the Solar System. Molecular clouds are important in star formation and galactic structure: it is possible that all stars form in molecular clouds, and as these are largely restricted to the spiral arms, they provide a new and highly specific tracer of the large-scale structure of the galactic system. (author)

  4. Nanopore analytics: sensing of single molecules.

    Science.gov (United States)

    Howorka, Stefan; Siwy, Zuzanna

    2009-08-01

    In nanopore analytics, individual molecules pass through a single nanopore giving rise to detectable temporary blockades in ionic pore current. Reflecting its simplicity, nanopore analytics has gained popularity and can be conducted with natural protein as well as man-made polymeric and inorganic pores. The spectrum of detectable analytes ranges from nucleic acids, peptides, proteins, and biomolecular complexes to organic polymers and small molecules. Apart from being an analytical tool, nanopores have developed into a general platform technology to investigate the biophysics, physicochemistry, and chemistry of individual molecules (critical review, 310 references).

  5. Multi-input multioutput orthogonal frequency division multiplexing radar waveform design for improving the detection performance of space-time adaptive processing

    Science.gov (United States)

    Wang, Hongyan

    2017-04-01

    This paper addresses the waveform optimization problem for improving the detection performance of multi-input multioutput (MIMO) orthogonal frequency division multiplexing (OFDM) radar-based space-time adaptive processing (STAP) in the complex environment. By maximizing the output signal-to-interference-and-noise-ratio (SINR) criterion, the waveform optimization problem for improving the detection performance of STAP, which is subjected to the constant modulus constraint, is derived. To tackle the resultant nonlinear and complicated optimization issue, a diagonal loading-based method is proposed to reformulate the issue as a semidefinite programming one; thereby, this problem can be solved very efficiently. In what follows, the optimized waveform can be obtained to maximize the output SINR of MIMO-OFDM such that the detection performance of STAP can be improved. The simulation results show that the proposed method can improve the output SINR detection performance considerably as compared with that of uncorrelated waveforms and the existing MIMO-based STAP method.

  6. Trans-cis molecular photoswitching in interstellar Space*

    Science.gov (United States)

    Cuadrado, S.; Goicoechea, J. R.; Roncero, O.; Aguado, A.; Tercero, B.; Cernicharo, J.

    2016-01-01

    As many organic molecules, formic acid (HCOOH) has two conformers (trans and cis). The energy barrier to internal conversion from trans to cis is much higher than the thermal energy available in molecular clouds. Thus, only the most stable conformer (trans) is expected to exist in detectable amounts. We report the first interstellar detection of cis-HCOOH. Its presence in ultraviolet (UV) irradiated gas exclusively (the Orion Bar photodissociation region), with a low trans-to-cis abundance ratio of 2.8 ± 1.0, supports a photoswitching mechanism: a given conformer absorbs a stellar photon that radiatively excites the molecule to electronic states above the interconversion barrier. Subsequent fluorescent decay leaves the molecule in a different conformer form. This mechanism, which we specifically study with ab initio quantum calculations, was not considered in Space before but likely induces structural changes of a variety of interstellar molecules submitted to UV radiation. PMID:28003686

  7. Narrow CSF space at high convexity and high midline areas in idiopathic normal pressure hydrocephalus detected by axial and coronal MRI

    International Nuclear Information System (INIS)

    Sasaki, Makoto; Honda, Satoshi; Yuasa, Tatsuhiko; Iwamura, Akihide; Shibata, Eri; Ohba, Hideki

    2008-01-01

    The aim of this study was to determine the performance of axial and coronal magnetic resonance imaging (MRI) in detecting the narrowing of the cerebrospinal fluid (CSF) space at the high convexity and high midline areas, which is speculated to be one of the clinical characteristics of idiopathic normal pressure hydrocephalus (iNPH). We retrospectively examined axial and coronal T1-weighted images of 14 iNPH patients and 12 age-matched controls. The narrowness of the CSF space at the high convexity/midline was blindly evaluated by five raters using a continuous confidence rating scale for receiver operating characteristic (ROC) analysis. Axial and coronal imaging accurately determined the presence of the narrow cisterns/sulci at the high convexity/midline and was capable of predicting probable/definite iNPH with a high degree of accuracy. there were also no significant differences in the detection of this finding between the axial and coronal images. Both axial and coronal T1-weighted MRI can detect the narrow CSF space at the high convexity/midline accurately and may therefore facilitate clinicians in choosing a management strategy for iNPH patients. (orig.)

  8. Narrow CSF space at high convexity and high midline areas in idiopathic normal pressure hydrocephalus detected by axial and coronal MRI

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Makoto [Iwate Medical University, Department of Radiology, Morioka (Japan); Honda, Satoshi [St. Luke' s International Hospital, Department of Radiology, Tokyo (Japan); Yuasa, Tatsuhiko; Iwamura, Akihide [Kohnodai Hospital, National Center of Neurology and Psychiatry, Department of Neurology, Ichikawa (Japan); Shibata, Eri [Iwate Medical University, Department of Neuropsychiatry, Morioka (Japan); Ohba, Hideki [Iwate Medical University, Department of Neurology, Morioka (Japan)

    2008-02-15

    The aim of this study was to determine the performance of axial and coronal magnetic resonance imaging (MRI) in detecting the narrowing of the cerebrospinal fluid (CSF) space at the high convexity and high midline areas, which is speculated to be one of the clinical characteristics of idiopathic normal pressure hydrocephalus (iNPH). We retrospectively examined axial and coronal T1-weighted images of 14 iNPH patients and 12 age-matched controls. The narrowness of the CSF space at the high convexity/midline was blindly evaluated by five raters using a continuous confidence rating scale for receiver operating characteristic (ROC) analysis. Axial and coronal imaging accurately determined the presence of the narrow cisterns/sulci at the high convexity/midline and was capable of predicting probable/definite iNPH with a high degree of accuracy. there were also no significant differences in the detection of this finding between the axial and coronal images. Both axial and coronal T1-weighted MRI can detect the narrow CSF space at the high convexity/midline accurately and may therefore facilitate clinicians in choosing a management strategy for iNPH patients. (orig.)

  9. Formation of Ultracold Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Cote, Robin [Univ. of Connecticut, Storrs, CT (United States)

    2016-01-28

    Advances in our ability to slow down and cool atoms and molecules to ultracold temperatures have paved the way to a revolution in basic research on molecules. Ultracold molecules are sensitive of very weak interactions, even when separated by large distances, which allow studies of the effect of those interactions on the behavior of molecules. In this program, we have explored ways to form ultracold molecules starting from pairs of atoms that have already reached the ultracold regime. We devised methods that enhance the efficiency of ultracold molecule production, for example by tuning external magnetic fields and using appropriate laser excitations. We also investigates the properties of those ultracold molecules, especially their de-excitation into stable molecules. We studied the possibility of creating new classes of ultra-long range molecules, named macrodimers, thousand times more extended than regular molecules. Again, such objects are possible because ultra low temperatures prevent their breakup by collision. Finally, we carried out calculations on how chemical reactions are affected and modified at ultracold temperatures. Normally, reactions become less effective as the temperature decreases, but at ultracold temperatures, they can become very effective. We studied this counter-intuitive behavior for benchmark chemical reactions involving molecular hydrogen.

  10. The status of molecules

    International Nuclear Information System (INIS)

    Barnes, T.; Oak Ridge National Lab., TN; Tennessee Univ., Knoxville, TN

    1994-06-01

    This report summarizes the experimental and theoretical status of hadronic molecules, which are weakly-bound states of two or more hadrons. We begin with a brief history of the subject and discuss a few good candidates, and then abstract some signatures for molecules which may be of interest in the classification of possible molecule states. Next we argue that a more general understanding of 2 → 2 hadron-hadron scattering amplitudes will be crucial for molecule searches, and discuss some of our recent work in this area. We conclude with a discussion of a few more recent molecule candidates (notably the f o (1710)) which are not well established as molecules but satisfy some of the expected signatures. (Author)

  11. Ultracold Polar Molecules

    Science.gov (United States)

    2016-04-01

    AFRL-AFOSR-UK-TR-2016-0005 Ultracold Polar Molecules Jeremy Hutson UNIVERSITY OF DURHAM Final Report 04/01/2016 DISTRIBUTION A: Distribution approved...DATES COVERED (From - To) 15-Jan-2010 to 14-Jul-2015 4. TITLE AND SUBTITLE Final Report on Grant FA8655-10-1-3033 on Ultracold Polar Molecules 5a...formation of ultracold 87RbCs molecules in their rovibrational ground state by magnetoassociation followed by STIRAP, resulting in 14 papers acknowledging

  12. Dialkylresorcinols as bacterial signaling molecules.

    Science.gov (United States)

    Brameyer, Sophie; Kresovic, Darko; Bode, Helge B; Heermann, Ralf

    2015-01-13

    It is well recognized that bacteria communicate via small diffusible molecules, a process termed quorum sensing. The best understood quorum sensing systems are those that use acylated homoserine lactones (AHLs) for communication. The prototype of those systems consists of a LuxI-like AHL synthase and a cognate LuxR receptor that detects the signal. However, many proteobacteria possess LuxR receptors, yet lack any LuxI-type synthase, and thus these receptors are referred to as LuxR orphans or solos. In addition to the well-known AHLs, little is known about the signaling molecules that are sensed by LuxR solos. Here, we describe a novel cell-cell communication system in the insect and human pathogen Photorhabdus asymbiotica. We identified the LuxR homolog PauR to sense dialkylresorcinols (DARs) and cyclohexanediones (CHDs) instead of AHLs as signals. The DarABC synthesis pathway produces the molecules, and the entire system emerged as important for virulence. Moreover, we have analyzed more than 90 different Photorhabdus strains by HPLC/MS and showed that these DARs and CHDs are specific to the human pathogen P. asymbiotica. On the basis of genomic evidence, 116 other bacterial species are putative DAR producers, among them many human pathogens. Therefore, we discuss the possibility of DARs as novel and widespread bacterial signaling molecules and show that bacterial cell-cell communication goes far beyond AHL signaling in nature.

  13. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    D)> HBr (0.83 D) > HI (0.45 D) [8]. Hence, these molecules can and do induce a dipole moment in the rare gas atoms when the two interact. The induced dipole moment is proportional to the inducing field E and the proportionality constant is the polariz- ability, i.e., μ i. = αE. However, as mentioned above, dispersion.

  14. Cold Rydberg molecules

    Science.gov (United States)

    Raithel, Georg; Zhao, Jianming

    2017-04-01

    Cold atomic systems have opened new frontiers at the interface of atomic and molecular physics. These include research on novel types of Rydberg molecules. Three types of molecules will be reviewed. Long-range, homonuclear Rydberg molecules, first predicted in [1] and observed in [2], are formed via low-energy electron scattering of the Rydberg electron from a ground-state atom within the Rydberg atom's volume. The binding mostly arises from S- and P-wave triplet scattering. We use a Fermi model that includes S-wave and P-wave singlet and triplet scattering, the fine structure coupling of the Rydberg atom and the hyperfine structure coupling of the 5S1/2 atom (in rubidium [3]). The hyperfine structure gives rise to mixed singlet-triplet potentials for both low-L and high-L Rydberg molecules [3]. A classification into Hund's cases [3, 4, 5] will be discussed. The talk further includes results on adiabatic potentials and adiabatic states of Rydberg-Rydberg molecules in Rb and Cs. These molecules, which have even larger bonding length than Rydberg-ground molecules, are formed via electrostatic multipole interactions. The leading interaction term of neutral Rydberg-Rydberg molecules is between two dipoles, while for ionic Rydberg molecules it is between a dipole and a monopole. NSF (PHY-1506093), NNSF of China (61475123).

  15. Plasmonics-Nanofluidics Hydrid Metamaterial: An Ultrasensitive Platform for Infrared Absorption Spectroscopy and Quantitative Measurement of Molecules.

    Science.gov (United States)

    Le, Thu H H; Tanaka, Takuo

    2017-10-24

    One of the most attractive potentials of plasmonic metamaterials is the amplification of intrinsically weak signals such as molecular infrared absorption or Raman scattering for detection applications. This effect, however, is only effective when target molecules are located at the enhanced electromagnetic field of the plasmonic structures (i.e., hot-spots). It is thus of significance to control the spatial overlapping of molecules and hot-spots, yet it is a long-standing challenge, since it involves the handling of molecules in nanoscale spaces. Here a metamaterial consisting of a nanofluidic channel with a depth of several tens of nanometers sandwiched between plasmonic resonators and a metal film enables the controllable delivery of small molecules into the most enhanced field arising from the quadrupole mode of the structures, forming a plasmon-molecular coupled system. It offers an ultrasensitive platform for detection of IR absorption and molecular sensing. Notably, the precise handling of molecules in a fixed and ultrasmall (10-100 nm) gap also addressed some critical issues in IR spectroscopy such as quantitative measurement and measurement in aqueous solution. Moreover, a drastic change in the reflectance characteristic resulting from the strong coupling between molecules and plasmonic structures indicates that molecules can also be utilized as triggers for actively switching the optical property of metamaterials.

  16. Development of an Immunoperoxidase Monolayer Assay for the Detection of Antibodies against Peste des Petits Ruminants Virus Based on BHK-21 Cell Line Stably Expressing the Goat Signaling Lymphocyte Activation Molecule.

    Directory of Open Access Journals (Sweden)

    Jialin Zhang

    Full Text Available From 2013 to 2015, peste des petits ruminants (PPR broke out in more than half of the provinces of China; thus, the application and development of diagnostic methods are very important for the control of PPR. Here, an immunoperoxidase monolayer assay (IPMA was developed to detect antibodies against PPR. However, during IPMA development, we found that Vero cells were not the appropriate choice because staining results were not easily observed. Therefore, we first established a baby hamster kidney-goat signaling lymphocyte activation molecule (BHK-SLAM cell line that could stably express goat SLAM for at least 20 generations. Compared with Vero cells, the PPR-mediated cytopathic effect occurred earlier in BHK-SLAM cells, and large syncytia appeared after virus infection. Based on this cell line and recombinant PPR virus expressing the green fluorescent protein (GFP (rPPRV-GFP, an IPMA for PPR diagnosis was developed. One hundred and ninety-eight PPR serum samples from goats or sheep were tested by the IPMA and virus neutralization test (VNT. Compared with the VNT, the sensitivity and specificity of the IPMA were 91% and 100%, respectively, and the coincidence rate of the two methods was 95.5%. The IPMA assay could be completed in 4 h, compared with more than 6 d for the VNT using rPPRV-GFP, and it is easily performed, as the staining results can be observed under a microscope. Additionally, unlike the VNT, the IPMA does not require antigen purification, which will reduce its cost. In conclusion, the established IPMA will be an alternative method that replaces the VNT for detecting antibodies against PPRV in the field.

  17. Detection of Autoantibodies against Recombinant Desmoglein 1 and 3 Molecules in Patients with Pemphigus vulgaris: Correlation with Disease Extent at the Time of Diagnosis and during Follow-Up

    Directory of Open Access Journals (Sweden)

    Anna Belloni-Fortina

    2009-01-01

    Full Text Available The recent availability of cDNA clones for pemphigus antigens has allowed the production of recombinant desmoglein 1 and desmoglein 3 molecules and the development of an ELISA approach in order to determine levels of antibodies to them. The aim of the study was to determine the relationship between autoantibodies levels and the extent of both mucosal and skin lesions in 20 patients with pemphigus vulgaris at the time of diagnosis and during follow-up. For the detection of autoantibodies by ELISA we used the recombinant proteins expressing overlapping sequences with the entire extracellular desmoglein 1 and desmoglein 3 domains. We showed that in presence of mucosal lesions there was a correlation between extension of mucosal involvement and autoantiboidies titres against both desmoglein 1 and desmoglein 3, whereas in presence of skin lesions there was a statistically significant correlation between extension of skin lesions and autoantibodies titres against desmoglein 3, but not against desmoglein 1. A not negligible number of patients showed variations of the desmoglein 3 autoantibodies titre which did not correlate with the severity of both cutaneous and mucosal involvement. Similar results were obtained analyzing autoantibodies titres against desmoglein 1. In conclusion, we believe that the utilization of recombinant desmoglein 1 and desmoglein 3 proteins by ELISA should be used with caution to monitor disease severity and response to therapy, although it remains a high specific test for the initial diagnosis of pemphigus and the identification of a change in the clinical phenotype of this condition.

  18. A novel technique using DNA denaturation to detect multiply induced single-strand breaks in a hydrated plasmid DNA molecule by X-ray and 4He2+ ion irradiation

    International Nuclear Information System (INIS)

    Yokoya, A.; Shikazono, N.; Fujii, K.; Noguchi, M.; Urushibara, A.

    2011-01-01

    To detect multiple single-strand breaks (SSBs) produced in plasmid DNA molecules by direct energy deposition from radiation tracks, we have developed a novel technique using DNA denaturation by which irradiated DNA is analysed as single-strand DNA (SS-DNA). The multiple SSBs that arise in both strands of DNA, but do not induce a double-strand break, are quantified as loss of SS-DNA using agarose gel electrophoresis. We have applied this method to X-ray and 4 He 2+ ion-irradiated samples of fully hydrated pUC18 plasmid DNA. The fractions of both SS-DNA and closed circular DNA (CC-DNA) exponentially decrease with the increasing dose of X rays and 4 He 2+ ions. The efficiency of the loss of SS-DNA was half that of CC-DNA for both types of irradiation, indicating that one of two strands in DNA is not broken when one SSB is produced in CC-DNA by irradiation. Contrary to our initial expectation, these results indicate that SSBs are not multiply induced even by high linear energy transfer radiation distributed in both strands. (authors)

  19. Detection of mRNA molecules coding for neuropeptide hormones of the pond snail Lymnaea stagnalis by radioactive and non-radioactive in situ hybridization: a model study for mRNA detection

    Energy Technology Data Exchange (ETDEWEB)

    Dirks, R.W.; Raap, A.K.; Van Minnen, J.; Vreugdenhil, E.; Smit, A.B.; Van der Ploeg, M.

    1989-01-01

    To develop and optimize non-radioactive in situ hybridization techniques for mRNA detection, we used the neuropeptidergic system of the pond snail Lymnaea stagnalis as a biological model system. First, we investigated the in situ hybridization procedure using radioactive-labeled cDNA and synthetic oligonucleotide probes specific for egg-laying hormone (ELH) mRNA and molluscan insulin-like peptide (MIP) mRNA. The results show an intense grain deposit above the caudodorsal cells and light-green cells expressing, respectively, ELH mRNA and MIP mRNA. Good results with relation to signal strength and tissue morphology were obtained with freeze-dry paraformaldehyde vapor fixation. The necessity to perform tissue pre-treatment appeared to be dependent on the cell type of interest. The optimized in situ hybridization protocol proved to be applicable using probes that are either sulfonated/transaminated or labeled with acetylaminofluorene (AAF). In situ hybridization of such haptenized probes led to intense and specific staining of the cytoplasm of the caudodorsal cells. Egg-laying hormone mRNA appeared not to be homogeneously distributed in the cytoplasm but showed a patch-like pattern. Nuclear and axoplasmic staining for mRNA was also observed.

  20. Detection of mRNA molecules coding for neuropeptide hormones of the pond snail Lymnaea stagnalis by radioactive and non-radioactive in situ hybridization: a model study for mRNA detection.

    Science.gov (United States)

    Dirks, R W; Raap, A K; Van Minnen, J; Vreugdenhil, E; Smit, A B; Van der Ploeg, M

    1989-01-01

    To develop and optimize non-radioactive in situ hybridization techniques for mRNA detection, we used the neuropeptidergic system of the pond snail Lymnaea stagnalis as a biological model system. First, we investigated the in situ hybridization procedure using radioactive-labeled cDNA and synthetic oligonucleotide probes specific for egg-laying hormone (ELH) mRNA and molluscan insulin-like peptide (MIP) mRNA. The results show an intense grain deposit above the caudodorsal cells and light-green cells expressing, respectively, ELH mRNA and MIP mRNA. Good results with relation to signal strength and tissue morphology were obtained with freeze-dry paraformaldehyde vapor fixation. The necessity to perform tissue pre-treatment appeared to be dependent on the cell type of interest. The optimized in situ hybridization protocol proved to be applicable using probes that are either sulfonated/transaminated or labeled with acetylaminofluorene (AAF). In situ hybridization of such haptenized probes led to intense and specific staining of the cytoplasm of the caudodorsal cells. Egg-laying hormone mRNA appeared not to be homogeneously distributed in the cytoplasm but showed a "patch-like" pattern. Nuclear and axoplasmic staining for mRNA was also observed.

  1. Molecule of the Month

    Indian Academy of Sciences (India)

    Atoms in a molecule generally prefer, particularly among the neighbouring ones, certain optimmn geometrical relationships. These are manifested in specific ranges of bond lengths, bond angles, torsion angles etc. As it always happens, chemists are interested in making molecules where these 'standard relationships' are ...

  2. Molecule of the Month

    Indian Academy of Sciences (India)

    Cyclo bu tadiene (1) has been one of the most popular molecules for experimentalists and theoreticians. This molecule is unstable as . it is antiaromatic ( 4,n electrons in a cyclic array). Even though some highly substituted cyclobutadienes, for example, compound 2 and the Fe(CO)3 complex of cyclobutadiene (3) are ...

  3. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 2. Single-Molecule Spectroscopy: Every Molecule is Different! Kankan Bhattacharyya. General Article Volume 20 Issue 2 February 2015 pp 151-164. Fulltext. Click here to view fulltext PDF. Permanent link:

  4. Algebraic theory of molecules

    CERN Document Server

    Iachello, F

    1995-01-01

    1. The Wave Mechanics of Diatomic Molecules. 2. Summary of Elements of Algebraic Theory. 3. Mechanics of Molecules. 4. Three-Body Algebraic Theory. 5. Four-Body Algebraic Theory. 6. Classical Limit and Coordinate Representation. 8. Prologue to the Future. Appendices. Properties of Lie Algebras; Coupling of Algebras; Hamiltonian Parameters

  5. Molecule of the Month.

    Indian Academy of Sciences (India)

    described here. Chemistry of aromatic molecules has a long history. Many molecules made up of multiple benzene-like rings have been isolated or made in the laboratory over the years. These are called polycondensed aromatic hydrocarbons (PAH for short). ... a bowl like symmetric polycyclic aromatic hydrocarbon of the.

  6. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 2. Single-Molecule Spectroscopy: Every Molecule is Different! ... Author Affiliations. Kankan Bhattacharyya1. Department of Physical Chemistry, Indian Association for the Cultivation of Science Jadavpur, Kolkata 700 032 India.

  7. Electrons in Molecules

    Indian Academy of Sciences (India)

    “What are electrons doing in molecules?” This is a deceptively simple question that scientists have been trying to answer for more than eighty years. With the advent of quantum mechanics in 1926, it became clear that we must understand the dynamics of electronic motion in atoms, molecules and solids in order to explain ...

  8. ISOLATED MOLECULES IN METALS

    NARCIS (Netherlands)

    1992-01-01

    In this paper, some results obtained on the formation of isolated molecules of composition SnOx in silver and SnFx in copper-are reviewed. Hyperfine interaction and ion beam interaction techniques were used for the identification of these molecules.

  9. Molecule of the Month

    Indian Academy of Sciences (India)

    Nature is an excellent synthetic organic chemist. Using mild reaction conditions and a few elemental combinations, a large variety of complex molecules are made in and around us. The atoms are put together in precise arrangements to enable the molecules to carry out different tasks with remarkable specificity.

  10. Single Molecule Studies on Dynamics in Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Daniela Täuber

    2013-09-01

    Full Text Available Single molecule (SM methods are able to resolve structure related dynamics of guest molecules in liquid crystals (LC. Highly diluted small dye molecules on the one hand explore structure formation and LC dynamics, on the other hand they report about a distortion caused by the guest molecules. The anisotropic structure of LC materials is used to retrieve specific conformation related properties of larger guest molecules like conjugated polymers. This in particular sheds light on organization mechanisms within biological cells, where large molecules are found in nematic LC surroundings. This review gives a short overview related to the application of highly sensitive SM detection schemes in LC.

  11. Single molecule studies on dynamics in liquid crystals.

    Science.gov (United States)

    Täuber, Daniela; von Borczyskowski, Christian

    2013-09-26

    Single molecule (SM) methods are able to resolve structure related dynamics of guest molecules in liquid crystals (LC). Highly diluted small dye molecules on the one hand explore structure formation and LC dynamics, on the other hand they report about a distortion caused by the guest molecules. The anisotropic structure of LC materials is used to retrieve specific conformation related properties of larger guest molecules like conjugated polymers. This in particular sheds light on organization mechanisms within biological cells, where large molecules are found in nematic LC surroundings. This review gives a short overview related to the application of highly sensitive SM detection schemes in LC.

  12. Fault Analysis of Space Station DC Power Systems-Using Neural Network Adaptive Wavelets to Detect Faults

    Science.gov (United States)

    Momoh, James A.; Wang, Yanchun; Dolce, James L.

    1997-01-01

    This paper describes the application of neural network adaptive wavelets for fault diagnosis of space station power system. The method combines wavelet transform with neural network by incorporating daughter wavelets into weights. Therefore, the wavelet transform and neural network training procedure become one stage, which avoids the complex computation of wavelet parameters and makes the procedure more straightforward. The simulation results show that the proposed method is very efficient for the identification of fault locations.

  13. Gamma Large Area Silicon Telescope (GLAST): Applying silicon strip detector technology to the detection of gamma rays in space

    International Nuclear Information System (INIS)

    Atwood, W.B.

    1993-06-01

    The recent discoveries and excitement generated by space satellite experiment EGRET (presently operating on Compton Gamma Ray Observatory -- CGRO) have prompted an investigation into modern detector technologies for the next generation space based gamma ray telescopes. The GLAST proposal is based on silicon strip detectors as the open-quotes technology of choiceclose quotes for space application: no consumables, no gas volume, robust (versus fragile), long lived, and self triggerable. The GLAST detector basically has two components: a tracking module preceding a calorimeter. The tracking module has planes of crossed strip (x,y) 300 μm pitch silicon detectors coupled to a thin radiator to measure the coordinates of converted electron-positron pairs. The gap between the layers (∼5 cm) provides a lever arm for track fitting resulting in an angular resolution of <0.1 degree at high energy. The status of this R ampersand D effort is discussed including details on triggering the instrument, the organization of the detector electronics and readout, and work on computer simulations to model this instrument

  14. On the Stability of Deinoxanthin Exposed to Mars Conditions during a Long-Term Space Mission and Implications for Biomarker Detection on Other Planets

    Directory of Open Access Journals (Sweden)

    Stefan Leuko

    2017-09-01

    Full Text Available Outer space, the final frontier, is a hostile and unforgiving place for any form of life as we know it. The unique environment of space allows for a close simulation of Mars surface conditions that cannot be simulated as accurately on the Earth. For this experiment, we tested the resistance of Deinococcus radiodurans to survive exposure to simulated Mars-like conditions in low-Earth orbit for a prolonged period of time as part of the Biology and Mars experiment (BIOMEX project. Special focus was placed on the integrity of the carotenoid deinoxanthin, which may serve as a potential biomarker to search for remnants of life on other planets. Survival was investigated by evaluating colony forming units, damage inflicted to the 16S rRNA gene by quantitative PCR, and the integrity and detectability of deinoxanthin by Raman spectroscopy. Exposure to space conditions had a strong detrimental effect on the survival of the strains and the 16S rRNA integrity, yet results show that deinoxanthin survives exposure to conditions as they prevail on Mars. Solar radiation is not only strongly detrimental to the survival and 16S rRNA integrity but also to the Raman signal of deinoxanthin. Samples not exposed to solar radiation showed only minuscule signs of deterioration. To test whether deinoxanthin is able to withstand the tested parameters without the protection of the cell, it was extracted from cell homogenate and exposed to high/low temperatures, vacuum, germicidal UV-C radiation, and simulated solar radiation. Results obtained by Raman investigations showed a strong resistance of deinoxanthin against outer space and Mars conditions, with the only exception of the exposure to simulated solar radiation. Therefore, deinoxanthin proved to be a suitable easily detectable biomarker for the search of Earth-like organic pigment-containing life on other planets.

  15. Dynamics of Activated Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, Amy S. [Univ. of Maryland, College Park, MD (United States)

    2016-11-16

    Experimental studies have been performed to investigate the collisional energy transfer processes of gas-phase molecules that contain large amounts of internal energy. Such molecules are prototypes for molecules under high temperature conditions relevant in combustion and information about their energy transfer mechanisms is needed for a detailed understanding and modeling of the chemistry. We use high resolution transient IR absorption spectroscopy to measure the full, nascent product distributions for collisions of small bath molecules that relax highly vibrationally excited pyrazine molecules with E=38000 cm-1 of vibrational energy. To perform these studies, we developed new instrumentation based on modern IR light sources to expand our experimental capabilities to investigate new molecules as collision partners. This final report describes our research in four areas: the characterization of a new transient absorption spectrometer and the results of state-resolved collision studies of pyrazine(E) with HCl, methane and ammonia. Through this research we have gained fundamental new insights into the microscopic details of relatively large complex molecules at high energy as they undergo quenching collisions and redistribute their energy.

  16. Enhanced change detection index for disaster response, recovery assessment and monitoring of accessibility and open spaces (camp sites)

    Science.gov (United States)

    de Alwis Pitts, Dilkushi A.; So, Emily

    2017-05-01

    The availability of Very High Resolution (VHR) optical sensors and a growing image archive that is frequently updated, allows the use of change detection in post-disaster recovery and monitoring for robust and rapid results. The proposed semi-automated GIS object-based method uses readily available pre-disaster GIS data and adds existing knowledge into the processing to enhance change detection. It also allows targeting specific types of changes pertaining to similar man-made objects. This change detection method is based on pre/post normalized index, gradient of intensity, texture and edge similarity filters within the object and a set of training data. Once the change is quantified, based on training data, the method can be used automatically to detect change in order to observe recovery over time in large areas. Analysis over time can also contribute to obtaining a full picture of the recovery and development after disaster, thereby giving managers a better understanding of productive management practices.

  17. Electron correlation in molecules

    CERN Document Server

    Wilson, S

    2007-01-01

    Electron correlation effects are of vital significance to the calculation of potential energy curves and surfaces, the study of molecular excitation processes, and in the theory of electron-molecule scattering. This text describes methods for addressing one of theoretical chemistry's central problems, the study of electron correlation effects in molecules.Although the energy associated with electron correlation is a small fraction of the total energy of an atom or molecule, it is of the same order of magnitude as most energies of chemical interest. If the solution of quantum mechanical equatio

  18. Review of crystalline structures of some selected homologous series of rod-like molecules capable of forming liquid crystalline phases.

    Science.gov (United States)

    Zugenmaier, Peter

    2011-01-01

    The crystal structures of four homologous series of rod-like molecules are reviewed, two of which form hydrogen bonds and two with a symmetric chemical constitution. Many of the compounds investigated turn into liquid crystalline phases upon temperature increase. It is of valuable interest to know possible conformations and possible packing arrangements as prerequisites to model liquid crystalline structures. The hydrogen bonds of homologous series of pure 4-(ω-hydroxyalkyloxy)-4'-hydroxybiphenyl (HnHBP, n the alkyloxy tail length) are realized through head to tail arrangements of the hydroxyl groups and crystallize except one compound in chiral space groups without the molecules containing any asymmetric carbon. The hydrogen bonds of the homologous series of 4-substituted benzoic acids with various lengths of the tail provide dimers through strong polar bonding of adjacent carboxyl groups and thus provide the stiff part of a mesogenic unit prerequisite for liquid crystalline phases. The homologous series of dialkanoyloxybiphenyls (BP-n, n = 1, 19), of which nine compounds could be crystallized, show liquid crystalline behavior for longer alkane chain lengths, despite the high mobility of the alkane chain ends already detectable in the crystal phase. A single molecule, half a molecule or two half molecules form the asymmetric unit in a centrosymmetric space group. The homologous series of 1,4-terephthalidene-bis-N-(4'-n-alkylaniline) (TBAA-n) exhibit a large variety of packing arrangements in the crystalline state, with or without relying on the symmetry center within the molecules.

  19. Graph-theoretic analysis of discrete-phase-space states for condition change detection and quantification of information

    Science.gov (United States)

    Hively, Lee M.

    2014-09-16

    Data collected from devices and human condition may be used to forewarn of critical events such as machine/structural failure or events from brain/heart wave data stroke. By monitoring the data, and determining what values are indicative of a failure forewarning, one can provide adequate notice of the impending failure in order to take preventive measures. This disclosure teaches a computer-based method to convert dynamical numeric data representing physical objects (unstructured data) into discrete-phase-space states, and hence into a graph (structured data) for extraction of condition change.

  20. Scientists Toast the Discovery of Vinyl Alcohol in Interstellar Space

    Science.gov (United States)

    2001-10-01

    Astronomers using the National Science Foundation's 12 Meter Telescope at Kitt Peak, AZ, have discovered the complex organic molecule vinyl alcohol in an interstellar cloud of dust and gas near the center of the Milky Way Galaxy. The discovery of this long-sought compound could reveal tantalizing clues to the mysterious origin of complex organic molecules in space. Vinyl Alcohol and its fellow isomers "The discovery of vinyl alcohol is significant," said Barry Turner, a scientist at the National Radio Astronomy Observatory (NRAO) in Charlottesville, Va., "because it gives us an important tool for understanding the formation of complex organic compounds in interstellar space. It may also help us better understand how life might arise elsewhere in the Cosmos." Vinyl alcohol is an important intermediary in many organic chemistry reactions on Earth, and the last of the three stable members of the C2H4O group of isomers (molecules with the same atoms, but in different arrangements) to be discovered in interstellar space. Turner and his colleague A. J. Apponi of the University of Arizona's Steward Observatory in Tucson detected the vinyl alcohol in Sagittarius B -- a massive molecular cloud located some 26,000 light-years from Earth near the center of our Galaxy. The astronomers were able to detect the specific radio signature of vinyl alcohol during the observational period of May and June of 2001. Their results have been accepted for publication in the Astrophysical Journal Letters. Of the approximately 125 molecules detected in interstellar space, scientists believe that most are formed by gas-phase chemistry, in which smaller molecules (and occasionally atoms) manage to "lock horns" when they collide in space. This process, though efficient at creating simple molecules, cannot explain how vinyl alcohol and other complex chemicals are formed in detectable amounts. For many years now, scientists have been searching for the right mechanism to explain how the building