Science.gov

Sample records for beacons

  1. Silex Beacon

    NASA Astrophysics Data System (ADS)

    Malaise, D.; Renard, M.

    1992-06-01

    A beacon developed and breadboarded by the SPACEBEL Instrumentation in the framework of the ESA Semiconducter Intersatellite Experiment (Silex) is described. The Silex Beacon is a powerful source aboard the GEO terminal, used by the LEO terminal to locate the latter. The paper describes the general architecture of the Silex Beacon and the flight model design and discusses the future developments. The far field pattern obtained by the breadboard is presented.

  2. Molecular beacons.

    PubMed

    Tan, Weihong; Wang, Kemim; Drake, Timothy J

    2004-10-01

    This opinion covers the field of molecular beacons (MBs), in which nucleic acids are molecularly engineered to have unique functions for the investigation of biomolecules. Molecular beacons have been used in a variety of formats, and this review discusses four: first, in vitro RNA and DNA monitoring; second, biosensors and biochips based on MBs; third, real-time monitoring of genes and gene expression in living systems; and finally, the next generation of molecular beacons that will be highly useful for studies with proteins, molecular beacon aptamers. These unique applications have shown that MBs holds great potential in genomics and proteomics where real-time molecular recognition with high sensitivity and excellent specificity is critical.

  3. BEACON PROGRAM.

    ERIC Educational Resources Information Center

    Ford Foundation, New York, NY.

    THE GREAT CITIES SCHOOL IMPROVEMENT PROGRAM AT LUDLOW SCHOOL, IN A PREDOMINANTLY PUERTO RICAN AND NEGRO NEIGHBORHOOD, HAS BEEN LABLED "BEACON" (BE A CITIZEN OF OUR NATION). IT ENDEAVORS TO ENRICH THE EDUCATIONAL EXPERIENCE OF THE STUDENTS THEREBY DEVELOPING THEIR MAXIMUM POTENTIALS FOR ACHIEVEMENT, AND CONTRIBUTING TO THEIR USEFULNESS AS CITIZENS.…

  4. Personal Beacon

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The MicroPLB (personal locator beacon) is a search and rescue satellite-aided tracking (SARSAT) transmitter. When activated it emits a distress signal to a constellation of internationally operated satellites. The endangered person's identity and location anywhere on Earth is automatically forwarded to central monitoring stations around the world. It is accurate to within just a few meters. The user uses the device to download navigation data from a global positioning satellite receiver. After the download is complete, the MicroPLB functions as a self-locating beacon. Also, it is the only PLB to use a safe battery. In the past, other PLB devices have used batteries that have enough volatility to explode with extreme force. It was developed by Microwave Monolithic, Inc. through SBIR funding from Glenn Research Center and Goddard Space Flight Center.

  5. Neuronal beacon.

    PubMed

    Black, B; Mondal, A; Kim, Y; Mohanty, S K

    2013-07-01

    The controlled navigation of the axonal growth cone of a neuron toward the dendrite of its synaptic partner neuron is the fundamental process in forming neuronal circuitry. While a number of technologies have been pursued for axonal guidance over the past decades, they are either invasive or not controllable with high spatial and temporal resolution and are often limited by low guidance efficacy. Here, we report a neuronal beacon based on light for highly efficient and controlled guidance of cortical primary neurons.

  6. Tester for Distress Beacons

    NASA Technical Reports Server (NTRS)

    Wade, W. R.

    1986-01-01

    Distress beacons on aircraft and boats checked for proper operation with aid of onboard monitor. Monitor mounted in aircraft cockpit or at wheel of boat. Connected to beacon electronics by cable. Monitor used with interface circuitry in beacon, which acts as buffer so that operation of beacon is not adversely affected if monitor is removed or if connecting cable is accidentally short circuited.

  7. SILEX beacon equipment

    NASA Astrophysics Data System (ADS)

    Crepin, P. J.; Leblay, P.; Malaise, D.

    The design and breadboarding of the beacon of the SILEX experimental optical link between geosynchronous Earth orbit and low Earth orbit terminals are considered. The aim of the SILEX experiment is to establish an intersatellite optical telecommunication link. The beacon will provide a powerful continuous wave light beam to allow terminal telescope alignment during acquisition phase. The beacon consists of four parts: the beacon electronics, the beacon emission unit, the optical fiber harness, and the beacon head. The system is described, special attention being given to the optical features.

  8. Great Plains Beacon.

    ERIC Educational Resources Information Center

    Simpson, Mary-Margaret, Ed.

    1993-01-01

    The 7 newsletter issues presented here review the efforts of 10 Midwestern community colleges to achieve greater leadership diversity on their campuses. Called Beacon projects (or collectively, the Beacon Project) after the grant that provided the funding for these efforts, the projects described cover a wide range of approaches. Among them are…

  9. A digital beacon receiver

    NASA Technical Reports Server (NTRS)

    Ransome, Peter D.

    1988-01-01

    A digital satellite beacon receiver is described which provides measurement information down to a carrier/noise density ratio approximately 15 dB below that required by a conventional (phase locked loop) design. When the beacon signal fades, accuracy degrades gracefully, and is restored immediately (without hysteresis) on signal recovery, even if the signal has faded into the noise. Benefits of the digital processing approach used include the minimization of operator adjustments, stability of the phase measuring circuits with time, repeatability between units, and compatibility with equipment not specifically designed for propagation measuring. The receiver has been developed for the European Olympus satellite which has continuous wave (CW) beacons at 12.5 and 29.7 GHz, and a switched polarization beacon at 19.8 GHz approximately, but the system can be reconfigured for CW and polarization-switched beacons at other frequencies.

  10. Catalytic molecular beacons.

    PubMed

    Stojanovic, M N; de Prada, P; Landry, D W

    2001-06-01

    We have constructed catalytic molecular beacons from a hammerhead-type deoxyribozyme by a modular design. The deoxyribozyme was engineered to contain a molecular beacon stem-loop module that, when closed, inhibits the deoxyribozyme module and is complementary to a target oligonucleotide. Binding of target oligonucleotides opens the beacon stem-loop and allosterically activates the deoxyribozyme module, which amplifies the recognition event through cleavage of a doubly labeled fluorescent substrate. The customized modular design of catalytic molecular beacons allows for any two single-stranded oligonucleotide sequences to be distinguished in homogenous solution in a single step. Our constructs demonstrate that antisense conformational triggers based on molecular beacons can be used to initiate catalytic events. The selectivity of the system is sufficient for analytical applications and has potential for the construction of deoxyribozyme-based drug delivery tools specifically activated in cells containing somatic mutations.

  11. A Beacon for Baltimore

    NASA Technical Reports Server (NTRS)

    1980-01-01

    High on the mainmast of the clipper Pride of Baltimore, crew members have installed a NASA-developed satellite beacon which enables continual tracking of the ship as she roams the seas on goodwill tours. The simple 10-pound beacon affixed to Pride's mainmast allows Baltimore's Operational Sail to keep track of the ship on its voyages to distant places. Once every minute, the compact, battery powered unit sends a radio signal to NASA's Nimbus-6 research satellite where the frequency shift of successive signals provides information for computing the ship's latitude and longitude.

  12. Digital Controller For Emergency Beacon

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.

    1990-01-01

    Prototype digital controller intended for use in 406-MHz emergency beacon. Undergoing development according to international specifications, 406-MHz emergency beacon system includes satellites providing worldwide monitoring of beacons, with Doppler tracking to locate each beacon within 5 km. Controller turns beacon on and off and generates binary codes identifying source (e.g., ship, aircraft, person, or vehicle on land). Codes transmitted by phase modulation. Knowing code, monitor attempts to communicate with user, monitor uses code information to dispatch rescue team appropriate to type and locations of carrier.

  13. Olympus beacon receiver

    NASA Technical Reports Server (NTRS)

    Ostergaard, Jens

    1988-01-01

    A medium-size Beacon Receiving System for reception and processing of the B1 (20 GHz) and B2 (30 GHz) beacons from Olympus has been developed. Integration of B1 and B2 receiving equipment into one system using one antenna and a common computer for control and data processing provides the advantages of a compact configuration and synchronization of the two receiver chains. Range for co-polar signal attenuation meaurement is about 30 dB for both beacons, increasing to 40 dB for B2 if the receivers are synchronized to B1. The accuracy is better than 0.5 dB. Cross-polarization discriminations of the order of 10 to 30 dB may be determined with an accuracy of 1 to 2 dB. A number of radiometers for complementary measurements of atmospheric attenuation of 13 to 30 GHz has also been constructed. A small multi-frequency system for operation around 22 GHz and 31 GHz is presently under development.

  14. Molecular beacon sequence design algorithm.

    PubMed

    Monroe, W Todd; Haselton, Frederick R

    2003-01-01

    A method based on Web-based tools is presented to design optimally functioning molecular beacons. Molecular beacons, fluorogenic hybridization probes, are a powerful tool for the rapid and specific detection of a particular nucleic acid sequence. However, their synthesis costs can be considerable. Since molecular beacon performance is based on its sequence, it is imperative to rationally design an optimal sequence before synthesis. The algorithm presented here uses simple Microsoft Excel formulas and macros to rank candidate sequences. This analysis is carried out using mfold structural predictions along with other free Web-based tools. For smaller laboratories where molecular beacons are not the focus of research, the public domain algorithm described here may be usefully employed to aid in molecular beacon design.

  15. SILEX Beacon equipment

    NASA Astrophysics Data System (ADS)

    Crepin, Pierre-Jean; Leblay, Pierrick; Haller, Regine; Tremillon, Isabelle; Sonon, Jean-Pierre

    1990-07-01

    The design of this equipment based on the use of nineteen 500 mW laser diodes is presented. The Beacon is a powerful and collimated optical source based upon semi-conductor lasers. This equipment is implemented in the SILEX GEO2 terminal and its function is to provide a continuous wave light beam towards the LEO or GEO1 satellites during the acquisition phases. The design was experimentally validated with a functional breadboard, and test results demonstrated the feasibility of every performance required by the SILEX system.

  16. Tripartite molecular beacons.

    PubMed

    Nutiu, Razvan; Li, Yingfu

    2002-09-15

    Molecular beacons (MBs) are hairpin-like fluorescent DNA probes that have single-mismatch detection capability. Although they are extremely useful for many solution-based nucleic acid detections, MBs are expensive probes for applications that require the use of a large number of different DNA probes due to the high cost and tedious procedures associated with probe synthesis and purification. In addition, since both ends of MB probes are covalently modified with chromophores, they do not offer the flexibility for fluorophore change and the capability for surface immobilization through free DNA ends. In this report, we describe an alternative form of MB, denoted tripartite molecular beacon (TMB), that may help overcome these problems. A TMB uses an unmodified oligodeoxyribonucleotide that forms a MB-like structure with two universal single-stranded arms to bring on a universal pair of oligodeoxyribonucleotides modified separately with a fluorophore and a quencher. We found that TMBs are as effective as standard MBs in signaling the presence of matching nucleic acid targets and in precisely discriminating targets that differ by a single nucleotide. TMBs have the necessary flexibility that may make MBs more affordable for various nucleic acid detection applications.

  17. PNA beacons for duplex DNA.

    PubMed

    Kuhn, H; Demidov, V V; Gildea, B D; Fiandaca, M J; Coull, J C; Frank-Kamenetskii, M D

    2001-08-01

    We report here on the hybridization of peptide nucleic acid (PNA)-based molecular beacons (MB) directly to duplex DNA sites locally exposed by PNA openers. Two stemless PNA beacons were tested, both featuring the same recognition sequence and fluorophore-quencher pair (Fluorescein and DABCYL, respectively) but differing in arrangement of these groups and net electrostatic charge. It was found that one PNA beacon rapidly hybridized, with the aid of openers, to its complementary target within duplex DNA at ambient conditions via formation of a PD-like loop. In contrast, the other PNA beacon bound more slowly to preopened duplex DNA target and only at elevated temperatures, although it readily hybridized to single-stranded (ss) DNA target. Besides a higher selectivity of hybridization provided by site-specific PNA openers, we expect this approach to be very useful in those MB applications when denaturation of the duplex DNA analytes is unfavorable or undesirable. Furthermore, we show that PNA beacons are advantageous over DNA beacons for analyzing unpurified/nondeproteinized DNA samples. This feature of PNA beacons and our innovative hybridization strategy may find applications in emerging fluorescent DNA diagnostics.

  18. 47 CFR 97.203 - Beacon station.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Beacon station. 97.203 Section 97.203... SERVICE Special Operations § 97.203 Beacon station. (a) Any amateur station licensed to a holder of a Technician, General, Advanced or Amateur Extra Class operator license may be a beacon. A holder of...

  19. 47 CFR 97.203 - Beacon station.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Beacon station. 97.203 Section 97.203... SERVICE Special Operations § 97.203 Beacon station. (a) Any amateur station licensed to a holder of a Technician, General, Advanced or Amateur Extra Class operator license may be a beacon. A holder of...

  20. 47 CFR 97.203 - Beacon station.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Beacon station. 97.203 Section 97.203... SERVICE Special Operations § 97.203 Beacon station. (a) Any amateur station licensed to a holder of a Technician, General, Advanced or Amateur Extra Class operator license may be a beacon. A holder of...

  1. Hybridization kinetics and thermodynamics of molecular beacons.

    PubMed

    Tsourkas, Andrew; Behlke, Mark A; Rose, Scott D; Bao, Gang

    2003-02-15

    Molecular beacons are increasingly being used in many applications involving nucleic acid detection and quantification. The stem-loop structure of molecular beacons provides a competing reaction for probe-target hybridization that serves to increase probe specificity, which is particularly useful when single-base discrimination is desired. To fully realize the potential of molecular beacons, it is necessary to optimize their structure. Here we report a systematic study of the thermodynamic and kinetic parameters that describe the molecular beacon structure-function relationship. Both probe and stem lengths are shown to have a significant impact on the binding specificity and hybridization kinetic rates of molecular beacons. Specifically, molecular beacons with longer stem lengths have an improved ability to discriminate between targets over a broader range of temperatures. However, this is accompanied by a decrease in the rate of molecular beacon-target hybridization. Molecular beacons with longer probe lengths tend to have lower dissociation constants, increased kinetic rate constants, and decreased specificity. Molecular beacons with very short stems have a lower signal-to-background ratio than molecular beacons with longer stems. These features have significant implications for the design of molecular beacons for various applications.

  2. Building the San Francisco Beacons.

    PubMed

    Eldredge, Sue; Piha, Sam; Levin, Fodi

    2002-01-01

    San Francisco's Beacon Initiative is designed to foster youth development on a large scale. Its intermediary, Community Network for Youth Development, used a theory of change process to forge consensus and create a road map to guide this large collaborative toward its long-term goals.

  3. Autonomous navigation using lunar beacons

    NASA Technical Reports Server (NTRS)

    Khatib, A. R.; Ellis, J.; French, J.; Null, G.; Yunck, T.; Wu, S.

    1983-01-01

    The concept of using lunar beacon signal transmission for on-board navigation for earth satellites and near-earth spacecraft is described. The system would require powerful transmitters on the earth-side of the moon's surface and black box receivers with antennae and microprocessors placed on board spacecraft for autonomous navigation. Spacecraft navigation requires three position and three velocity elements to establish location coordinates. Two beacons could be soft-landed on the lunar surface at the limits of allowable separation and each would transmit a wide-beam signal with cones reaching GEO heights and be strong enough to be received by small antennae in near-earth orbit. The black box processor would perform on-board computation with one-way Doppler/range data and dynamical models. Alternatively, GEO satellites such as the GPS or TDRSS spacecraft can be used with interferometric techniques to provide decimeter-level accuracy for aircraft navigation.

  4. Switchable cucurbituril-bipyridine beacons.

    PubMed

    Sinha, Mantosh K; Reany, Ofer; Parvari, Galit; Karmakar, Ananta; Keinan, Ehud

    2010-08-01

    4-Aminobipyridine derivatives form strong inclusion complexes with cucurbit[6]uril, exhibiting remarkably large enhancements in fluorescence intensity and quantum yields. The remarkable complexation-induced pK(a) shift (DeltapK(a)=3.3) highlights the strong charge-dipole interaction upon binding. The reversible binding phenomenon can be used for the design of switchable beacons that can be incorporated into cascades of binding networks. This concept is demonstrated herein by three different applications: 1) a switchable fluorescent beacon for chemical sensing of transition metals and other ligands; 2) direct measurement of binding constants between cucurbit[6]uril and various nonfluorescent guest molecules; and 3) quantitative monitoring of biocatalytic reactions and determination of their kinetic parameters. The latter application is illustrated by the hydrolysis of an amide catalyzed by penicillin G acylase and by the elimination reaction of a beta-cabamoyloxy ketone catalyzed by aldolase antibody 38C2.

  5. Molecular beacons: an optimal multifunctional biological probe.

    PubMed

    Li, Yongsheng; Zhou, Xiaoyan; Ye, Duyun

    2008-09-01

    Molecular beacon technology is set up based on fluorescence resonance energy transfer (FRET) and the complementary pairing principles. These fluorescent molecular probes, which are very highly specific and sensitive, have now become one important tool in medical and biological researches. This review introduces the molecular beacons structure, principle, the main impact factors, the labeling of the molecular beacons, and research progress on molecular beacons fluorescent-label in the polymerase chain reaction (PCR), DNA sequence analysis, gene dynamic detection in living cells, protein (enzyme)-nucleic acid interactions and applications in clinical medicine.

  6. Locked nucleic acid molecular beacons.

    PubMed

    Wang, Lin; Yang, Chaoyong James; Medley, Colin D; Benner, Steven A; Tan, Weihong

    2005-11-16

    A novel LNA-MB (molecular beacon based on locked nucleic acid bases) has been designed and investigated. It exhibits very high melting temperature and is thermally stable, shows superior single base mismatch discrimination capability, and is stable against digestion by nuclease and has no binding with single-stranded DNA binding proteins. The LNA-MB will be widely useful in a variety of areas, especially for in vivo hybridization studies.

  7. Design of a molecular beacon PNA.

    PubMed

    Kitagawa, Fumihiko; Ohori, Youji; Ikeda, Hisafumi; Fujimori, Humihiro; Murakami, Yasuhumi; Nakamura, Yushin

    2002-01-01

    We have designed a novel dual-labeled PNA oligomer, having both a fluorescent dye and a quencher, by utilizing key compounds 1 and 2. We showed that the designed dual-labeled PNA oligomer works as a molecular beacon PNA. We also investigated the optimization of a stem-loop structure which can supersensitize the function as a molecular beacon PNA.

  8. Quantum dot molecular beacons for DNA detection.

    PubMed

    Cady, Nathaniel C

    2009-01-01

    Molecular beacons have become an important fluorescent probe for sequence-specific DNA detection. To improve the sensitivity and robustness of molecular beacon assays, fluorescent semiconductor quantum dots (QDs) are now being used as the fluorescent moiety for molecular beacon synthesis. Multiple linkage strategies can be used for attaching molecular beacon DNA to QDs, and multiple quenchers, including gold particles, can be used for fluorescence quenching. Covalent attachment of QDs to DNA can be achieved through amide linkage, and affinity-based attachment can be achieved with streptavidin-biotin linkage. We have shown that these linkage strategies can be used to successfully create quantum dot molecular beacons that can be used in DNA detection assays with high specificity.

  9. The ANTARES optical beacon system

    NASA Astrophysics Data System (ADS)

    Ageron, M.; Aguilar, J. A.; Albert, A.; Ameli, F.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardellier-Desages, F.; Aslanides, E.; Aubert, J.-J.; Auer, R.; Barbarito, E.; Basa, S.; Battaglieri, M.; Becherini, Y.; Beltramelli, J.; Bertin, V.; Bigi, A.; Billault, M.; Blaes, R.; de Botton, N.; Bouwhuis, M. C.; Bradbury, S. M.; Bruijn, R.; Brunner, J.; Burgio, G. F.; Busto, J.; Cafagna, F.; Caillat, L.; Calzas, A.; Capone, A.; Caponetto, L.; Carmona, E.; Carr, J.; Cartwright, S. L.; Castel, D.; Castorina, E.; Cavasinni, V.; Cecchini, S.; Ceres, A.; Charvis, P.; Chauchot, P.; Chiarusi, T.; Circella, M.; Colnard, C.; Compère, C.; Coniglione, R.; Cottini, N.; Coyle, P.; Cuneo, S.; Cussatlegras, A.-S.; Damy, G.; van Dantzig, R.; de Bonis, G.; de Marzo, C.; de Vita, R.; Dekeyser, I.; Delagnes, E.; Denans, D.; Deschamps, A.; Destelle, J.-J.; Dinkespieler, B.; Distefano, C.; Donzaud, C.; Drogou, J.-F.; Druillole, F.; Durand, D.; Ernenwein, J.-P.; Escoffier, S.; Falchini, E.; Favard, S.; Fehr, F.; Feinstein, F.; Ferry, S.; Fiorello, C.; Flaminio, V.; Fratini, K.; Fuda, J.-L.; Galeotti, S.; Gallone, J.-M.; Giacomelli, G.; Girard, N.; Gojak, C.; Goret, Ph.; Graf, K.; Hallewell, G.; Harakeh, M. N.; Hartmann, B.; Heijboer, A.; Heine, E.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hoffman, C.; Hogenbirk, J.; Hubbard, J. R.; Jaquet, M.; Jaspers, M.; de Jong, M.; Jouvenot, F.; Kalantar-Nayestanaki, N.; Kappes, A.; Karg, T.; Katz, U.; Keller, P.; Kok, E.; Kok, H.; Kooijman, P.; Kopper, C.; Korolkova, E. V.; Kouchner, A.; Kretschmer, W.; Kruijer, A.; Kuch, S.; Kudryavstev, V. A.; Lagier, P.; Lahmann, R.; Lamanna, G.; Lamare, P.; Lambard, G.; Languillat, J.-C.; Laschinsky, H.; Lavalle, J.; Le Guen, Y.; Le Provost, H.; Le van Suu, A.; Lefèvre, D.; Legou, T.; Lelaizant, G.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Louis, F.; Lucarelli, F.; Lyashuk, V.; Marcelin, M.; Margiotta, A.; Masullo, R.; Mazéas, F.; Mazure, A.; McMillan, J. E.; Megna, R.; Melissas, M.; Migneco, E.; Milovanovic, A.; Mongelli, M.; Montaruli, T.; Morganti, M.; Moscoso, L.; Musumeci, M.; Naumann-Godo, M.; Naumann, C.; Niess, V.; Noble, T.; Olivetto, C.; Ostasch, R.; Palanque-Delabrouille, N.; Payre, P.; Peek, H.; Perez, A.; Petta, C.; Piattelli, P.; Pillet, R.; Pineau, J.-P.; Poinsignon, J.; Popa, V.; Pradier, T.; Racca, C.; Randazzo, N.; van Randwijk, J.; Real, D.; van Rens, B.; Réthoré, F.; Rewiersma, P.; Riccobene, G.; Rigaud, V.; Ripani, M.; Roca, V.; Roda, C.; Rolin, J. F.; Rose, H. J.; Rostovtsev, A.; Roux, J.; Ruppi, M.; Russo, G. V.; Rusydi, G.; Salesa, F.; Salomon, K.; Sapienza, P.; Schmitt, F.; Schuller, J.-P.; Shanidze, R.; Sokalski, I.; Spona, T.; Spurio, M.; van der Steenhoven, G.; Stolarczyk, T.; Streeb, K.; Sulak, L.; Taiuti, M.; Tamburini, C.; Tao, C.; Terreni, G.; Thompson, L. F.; Urbano, F.; Valdy, P.; Valente, V.; Vallage, B.; Vaudaine, G.; Venekamp, G.; Verlaat, B.; Vernin, P.; de Vries-Uiterweerd, G.; van Wijk, R.; Wijnker, G.; de Witt Huberts, P.; Wobbe, G.; de Wolf, E.; Yao, A.-F.; Zaborov, D.; Zaccone, H.; Zornoza, J. D.; Zúñiga, J.

    2007-08-01

    ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three-dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular, when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.

  10. In vitro selection of molecular beacons.

    PubMed

    Rajendran, Manjula; Ellington, Andrew D

    2003-10-01

    While molecular beacons are primarily known as biosensors for the detection of nucleic acids, it has proven possible to adapt other nucleic acid binding species (aptamers) to function in a manner similar to molecular beacons, yielding fluorescent signals only in the presence of a cognate ligand. Unfortunately, engineering aptamer beacons requires a detailed knowledge of aptamer sequence and structure. In order to develop a general method for the direct selection of aptamer beacons we have first developed a selection method for molecular beacons. A pool of random sequence DNA molecules were immobilized via a capture oligonucleotide on an affinity column, and those variants that could be released from the column by a target oligonucleotide were amplified. After nine rounds of selection and amplification the elution characteristics of the population were greatly improved. A fluorescent reporter in the selected beacons was located adjacent to a DABCYL moiety in the capture oligonucleotide; addition of the target oligonucleotide led to release of the capture oligonucleotide and up to a 17-fold increase in fluorescence. Signaling was specific for the target oligonucleotide, and occurred via a novel mechanism, relative to designed molecular beacons. When the target oligonucleotide is bound it can form a stacked helical junction with an intramolecular hairpin in the selected beacon; formation of the intramolecular hairpin in turn leads to release of the capture oligonucleotide. The ability to select molecular beacons may prove useful for identifying available sites on complex targets, such as mRNAs, while the method for selection can be easily generalized to other, non-nucleic acid target classes.

  11. Uncertainty evaluation in BEACON power distribution monitoring

    SciTech Connect

    Morita, T.; Goldstein, N.P. )

    1989-11-01

    BEACON is an advanced operational core support package that has a three-dimensional nodal code as its cornerstone. The three-dimensional calculation includes all necessary pressurized water reactor feedback effects. The generation of the measured power distribution from the core instrumentation is one of the primary functions of the core-monitoring software. The purpose of this paper is to discuss evaluation of the uncertainty in the measured assembly power from the BEACON system. The study covers not only the normal operating conditions, but off-normal situations to demonstrate BEACON's applicability for that condition.

  12. Polyvalent carbocyanine molecular beacons for molecular recognitions.

    PubMed

    Ye, Yunpeng; Bloch, Sharon; Achilefu, Samuel

    2004-06-30

    Polyvalent carboxylate-terminating near-infrared (NIR) carbocyanine molecular beacons were prepared by homologation of reactive carboxyl groups of the beacon with imino diacetic acid. Their conjugation with unprotected d-(+)-glucosamine gave dendritic arrays of the carbohydrate on an inner NIR chromophore core. In vivo evaluation of the dendritic glucosamine constructs shows enhanced uptake in proliferating tumor cells relative to surrounding normal tissue. The structural framework of these polyvalent beacons permits the amplification by synergistic effects of a variety of bioactive motifs or chemical sensors in molecular recognition interactions without dramatic change of their desirable NIR spectral properties.

  13. Bootstrap beacon creation for overcoming the effects of beacon anisoplanatism in a laser beam projection system.

    PubMed

    Sergeyev, Aleksandr V; Piatrou, Piotr; Roggemann, Michael C

    2008-05-01

    We address the problem of using adaptive optics to deliver power from an airborne laser platform to a ground target through atmospheric turbulence under conditions of strong scintillation and anisoplanatism. We explore three options for creating a beacon for use in adaptive optics beam control: scattering laser energy from the target, using a single uncompensated Rayleigh beacon, and using a series of compensated Rayleigh beacons. We demonstrate that using a series of compensated Rayleigh beacons distributed along the path provides the best beam compensation.

  14. Inside Beacon Hill: Bertrand Russell as Schoolmaster.

    ERIC Educational Resources Information Center

    Jespersen, Shirley

    1987-01-01

    The author describes the life and theories of Bertrand Russell, founder of Beacon Hill School. Russell's educational theories centered on the personal autonomy of the student and democratization of the learning process. (CH)

  15. Direct selection of RNA beacon aptamers.

    PubMed

    Morse, Daniel P

    2007-07-20

    A method for the direct selection of RNA molecules that can be easily converted into beacon aptamers is presented. Beacon aptamers are fluorescently labeled nucleic acids that signal the presence of a specific ligand through changes in fluorescence intensity. Typically, ligand binding causes an increase in fluorescence intensity by inducing a conformational change that separates a fluorophore/quencher pair. The method presented here simultaneously selects for ligand binding and induction of an appropriate conformational change. The method was tested by selecting RNA molecules that can detect the aminoglycoside antibiotic tobramycin. After 14 rounds of selection, two sequence families emerged. Upon conversion into beacon aptamers, representatives of the two selected sequence families specifically detected tobramycin, while a negative control RNA that did not survive the selection protocol did not function as a tobramycin beacon aptamer.

  16. Building a million beacon map

    NASA Astrophysics Data System (ADS)

    Julier, Simon J.; Uhlmann, Jeffrey K.

    2001-10-01

    Many future missions for mobile robots demand multi-robot systems which are capable of operating in large environments for long periods of time. A critical capability is that each robot must be able to localize itself. However, GPS cannot be used in many environments (such as within city streets, under water, indoors, beneath foliage or extra-terrestrial robotic missions) where mobile robots are likely to become commonplace. A widely researched alternative is Simultaneous Localization and Map Building (SLAM): the vehicle constructs a map and, concurrently, estimates its own position. In this paper we consider the problem of building and maintaining an extremely large map (of one million beacons). We describe a fully distributed, highly scaleable SLAM algorithm which is based on distributed data fusion systems. A central map is maintained in global coordinates using the Split Covariance Intersection (SCI) algorithm. Relative and local maps are run independently of the central map and their estimates are periodically fused with the central map.

  17. Beacon data acquisition and display system

    DOEpatents

    Skogmo, D.G.; Black, B.D.

    1991-12-17

    A system for transmitting aircraft beacon information received by a secondary surveillance radar through telephone lines to a remote display includes a digitizer connected to the radar for preparing a serial file of data records containing position and identification information of the beacons detected by each sweep of the radar. This information is transmitted through the telephone lines to a remote computer where it is displayed. 6 figures.

  18. Beacon data acquisition and display system

    SciTech Connect

    Skogmo, David G.; Black, Billy D.

    1991-01-01

    A system for transmitting aircraft beacon information received by a secondary surveillance radar through telephone lines to a remote display includes a digitizer connected to the radar for preparing a serial file of data records containing position and identification information of the beacons detected by each sweep of the radar. This information is transmitted through the telephone lines to a remote computer where it is displayed.

  19. Laser Transmitter Aims At Laser Beacon

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James R.

    1993-01-01

    Transmitter part of developmental optical communication system. Compact, lightweight, partially-self-aiming laser transmitter built to verify some capabilities of developmental free-space optical communication system. Design capable of providing 0.5 Mbps data return over range equal to Moon-Earth distance. Breadboard of transmitting terminal constructed and tested in laboratory. Prototype transmitter includes receiving circuitry that keeps it aimed at beacon, once brought into initial alignment within about 1.7 degrees of line of sight to beacon.

  20. Searching for Cost-Optimized Interstellar Beacons

    NASA Technical Reports Server (NTRS)

    Benford, Gregory; Benford, James; Benford, Dominic

    2010-01-01

    What would SETI beacon transmitters be like if built by civilizations that had a variety of motives but cared about cost? In a companion paper, we presented how, for fixed power density in the far field, a cost-optimum interstellar beacon system could be built. Here, we consider how we should search for a beacon if it were produced by a civilization similar to ours. High-power transmitters could be built for a wide variety of motives other than the need for two-way communication, this would include beacons built to be seen over thousands of light-years. Extraterrestrial beacon builders would likely have to contend with economic pressures just as their terrestrial counterparts do. Cost, spectral lines near 1GHz, and interstellar scintillation favor radiating frequencies substantially above the classic "water hole." Therefore, the transmission strategy for a distant, cost-conscious beacon would be a rapid scan of the galactic plane with the intent to cover the angular space. Such pulses would be infrequent events for the receiver. Such beacons built by distant, advanced, wealthy societies would have very different characteristics from what SETI researchers seek. Future searches should pay special attention to areas along the galactic disk where SETI searches have seen coherent signals that have not recurred on the limited listening time intervals we have used. We will need to wait for recurring events that may arrive in intermittent bursts. Several new SETI search strategies have emerged from these ideas. We propose a new test for beacons that is based on the Life Plane hypotheses.

  1. Searching for cost-optimized interstellar beacons.

    PubMed

    Benford, Gregory; Benford, James; Benford, Dominic

    2010-06-01

    What would SETI beacon transmitters be like if built by civilizations that had a variety of motives but cared about cost? In a companion paper, we presented how, for fixed power density in the far field, a cost-optimum interstellar beacon system could be built. Here, we consider how we should search for a beacon if it were produced by a civilization similar to ours. High-power transmitters could be built for a wide variety of motives other than the need for two-way communication; this would include beacons built to be seen over thousands of light-years. Extraterrestrial beacon builders would likely have to contend with economic pressures just as their terrestrial counterparts do. Cost, spectral lines near 1 GHz, and interstellar scintillation favor radiating frequencies substantially above the classic "water hole." Therefore, the transmission strategy for a distant, cost-conscious beacon would be a rapid scan of the galactic plane with the intent to cover the angular space. Such pulses would be infrequent events for the receiver. Such beacons built by distant, advanced, wealthy societies would have very different characteristics from what SETI researchers seek. Future searches should pay special attention to areas along the galactic disk where SETI searches have seen coherent signals that have not recurred on the limited listening time intervals we have used. We will need to wait for recurring events that may arrive in intermittent bursts. Several new SETI search strategies have emerged from these ideas. We propose a new test for beacons that is based on the Life Plane hypotheses.

  2. Searching for cost-optimized interstellar beacons.

    PubMed

    Benford, Gregory; Benford, James; Benford, Dominic

    2010-06-01

    What would SETI beacon transmitters be like if built by civilizations that had a variety of motives but cared about cost? In a companion paper, we presented how, for fixed power density in the far field, a cost-optimum interstellar beacon system could be built. Here, we consider how we should search for a beacon if it were produced by a civilization similar to ours. High-power transmitters could be built for a wide variety of motives other than the need for two-way communication; this would include beacons built to be seen over thousands of light-years. Extraterrestrial beacon builders would likely have to contend with economic pressures just as their terrestrial counterparts do. Cost, spectral lines near 1 GHz, and interstellar scintillation favor radiating frequencies substantially above the classic "water hole." Therefore, the transmission strategy for a distant, cost-conscious beacon would be a rapid scan of the galactic plane with the intent to cover the angular space. Such pulses would be infrequent events for the receiver. Such beacons built by distant, advanced, wealthy societies would have very different characteristics from what SETI researchers seek. Future searches should pay special attention to areas along the galactic disk where SETI searches have seen coherent signals that have not recurred on the limited listening time intervals we have used. We will need to wait for recurring events that may arrive in intermittent bursts. Several new SETI search strategies have emerged from these ideas. We propose a new test for beacons that is based on the Life Plane hypotheses. PMID:20624057

  3. Monitoring helicase activity with molecular beacons.

    PubMed

    Belon, Craig A; Frick, David N

    2008-10-01

    A high-throughput, fluorescence-based helicase assay using molecular beacons is described. The assay is tested using the NS3 helicase encoded by the hepatitis C virus (HCV) and is shown to accurately monitor helicase action on both DNA and RNA. In the assay, a ssDNA oligonucleotide molecular beacon, featuring a fluorescent moiety attached to one end and a quencher attached to the other, is annealed to a second longer DNA or RNA oligonucleotide. Upon strand separation by a helicase and ATP, the beacon strand forms an intramolecular hairpin that brings the tethered fluorescent and quencher molecules into juxtaposition, quenching fluorescence. Unlike currently available real-time helicase assays, the molecular beacon-based helicase assay is irreversible. As such, it does not require the addition of extra DNA strands to prevent products from re-annealing. Several variants of the new assay are described and experimentally verified using both Cy3 and Cy5 beacons, including one based on a sequence from the HCV genome. The HCV genome-based molecular beacon helicase assay is used to demonstrate how such an assay can be used in high-throughput screens and to analyze HCV helicase inhibitors.

  4. Evaluation of acoustic beacon characteristics for navigation tasks.

    PubMed

    Tran, T V; Letowski, T; Abouchacra, K S

    2000-06-01

    The goal of the present study was to investigate the human factors issues related to acoustic beacons used for auditory navigation. Specific issues addressed were: (1) the effect of various beacon characteristics on human accuracy in turning toward the direction of the acoustic beacon; (2) the difference between real and virtual environments on human accuracy in turning toward the acoustic beacon; and (3) the perceived sound quality of various acoustic beacons. Three experiments were conducted in which acoustic beacons were presented in a background of 80 dBA pink noise. Results of the localization tasks revealed that (a) presentation mode (continuous versus pulsed beacon sound) did not affect the overall localization accuracy or number of front-back confusion errors; and (b) the type of acoustic beacon affected the size of localization error. Results of the sound quality assessment indicated that listeners had definite preferences regarding the type of sound being used as a beacon, with (a) non-speech beacons preferred over speech beacons, (b) a beacon repetition rate of 1.1 rps preferred over either the 0.7 or 2.5 rps rates, and (c) a continuous operation of a beacon preferred over a pulsed operation. Finally, sound quality ratings and localization errors were highly negatively correlated. This finding demonstrates the usefulness and practical values of sound quality judgements for audio display design and evaluation.

  5. Messaging with Cost-Optimized Interstellar Beacons

    NASA Technical Reports Server (NTRS)

    Benford, James; Benford, Gregory; Benford, Dominic

    2010-01-01

    On Earth, how would we build galactic-scale beacons to attract the attention of extraterrestrials, as some have suggested we should do? From the point of view of expense to a builder on Earth, experience shows an optimum trade-off. This emerges by minimizing the cost of producing a desired power density at long range, which determines the maximum range of detectability of a transmitted signal. We derive general relations for cost-optimal aperture and power. For linear dependence of capital cost on transmitter power and antenna area, minimum capital cost occurs when the cost is equally divided between antenna gain and radiated power. For nonlinear power-law dependence, a similar simple division occurs. This is validated in cost data for many systems; industry uses this cost optimum as a rule of thumb. Costs of pulsed cost-efficient transmitters are estimated from these relations by using current cost parameters ($/W, $/sq m) as a basis. We show the scaling and give examples of such beacons. Galactic-scale beacons can be built for a few billion dollars with our present technology. Such beacons have narrow "searchlight" beams and short "dwell times" when the beacon would be seen by an alien observer in their sky. More-powerful beacons are more efficient and have economies of scale: cost scales only linearly with range R, not as R(exp 2), so number of stars radiated to increases as the square of cost. On a cost basis, they will likely transmit at higher microwave frequencies, -10 GHz. The natural corridor to broadcast is along the galactic radius or along the local spiral galactic arm we are in. A companion paper asks "If someone like us were to produce a beacon, how should we look for it?"

  6. Messaging with cost-optimized interstellar beacons.

    PubMed

    Benford, James; Benford, Gregory; Benford, Dominic

    2010-06-01

    On Earth, how would we build galactic-scale beacons to attract the attention of extraterrestrials, as some have suggested we should do? From the point of view of expense to a builder on Earth, experience shows an optimum trade-off. This emerges by minimizing the cost of producing a desired power density at long range, which determines the maximum range of detectability of a transmitted signal. We derive general relations for cost-optimal aperture and power. For linear dependence of capital cost on transmitter power and antenna area, minimum capital cost occurs when the cost is equally divided between antenna gain and radiated power. For nonlinear power-law dependence, a similar simple division occurs. This is validated in cost data for many systems; industry uses this cost optimum as a rule of thumb. Costs of pulsed cost-efficient transmitters are estimated from these relations by using current cost parameters ($/W, $/m(2)) as a basis. We show the scaling and give examples of such beacons. Galactic-scale beacons can be built for a few billion dollars with our present technology. Such beacons have narrow "searchlight" beams and short "dwell times" when the beacon would be seen by an alien observer in their sky. More-powerful beacons are more efficient and have economies of scale: cost scales only linearly with range R, not as R(2), so number of stars radiated to increases as the square of cost. On a cost basis, they will likely transmit at higher microwave frequencies, approximately 10 GHz. The natural corridor to broadcast is along the galactic radius or along the local spiral galactic arm we are in. A companion paper asks "If someone like us were to produce a beacon, how should we look for it?"

  7. Messaging with Cost-Optimized Interstellar Beacons

    NASA Astrophysics Data System (ADS)

    Benford, James; Benford, Gregory; Benford, Dominic

    2010-06-01

    On Earth, how would we build galactic-scale beacons to attract the attention of extraterrestrials, as some have suggested we should do? From the point of view of expense to a builder on Earth, experience shows an optimum trade-off. This emerges by minimizing the cost of producing a desired power density at long range, which determines the maximum range of detectability of a transmitted signal. We derive general relations for cost-optimal aperture and power. For linear dependence of capital cost on transmitter power and antenna area, minimum capital cost occurs when the cost is equally divided between antenna gain and radiated power. For nonlinear power-law dependence, a similar simple division occurs. This is validated in cost data for many systems; industry uses this cost optimum as a rule of thumb. Costs of pulsed cost-efficient transmitters are estimated from these relations by using current cost parameters (/W, /m2) as a basis. We show the scaling and give examples of such beacons. Galactic-scale beacons can be built for a few billion dollars with our present technology. Such beacons have narrow "searchlight" beams and short "dwell times" when the beacon would be seen by an alien observer in their sky. More-powerful beacons are more efficient and have economies of scale: cost scales only linearly with range R, not as R2, so number of stars radiated to iincreases as the square of cost. On a cost basis, they will likely transmit at higher microwave frequencies, ˜10 GHz. The natural corridor to broadcast is along the galactic radius or along the local spiral galactic arm we are in. A companion paper asks "If someone like us were to produce a beacon, how should we look for it?"

  8. 33 CFR 62.23 - Beacons and buoys.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Beacons and buoys. 62.23 Section... UNITED STATES AIDS TO NAVIGATION SYSTEM The U.S. Aids to Navigation System § 62.23 Beacons and buoys. (a... navigation. The primary components of the U.S. Aids to Navigation System are beacons and buoys. (b)...

  9. 14 CFR 171.269 - Marker beacon performance requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Marker beacon performance requirements. 171.269 Section 171.269 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Landing System (ISMLS) § 171.269 Marker beacon performance requirements. ISMLS marker beacon...

  10. 33 CFR 62.23 - Beacons and buoys.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Beacons and buoys. 62.23 Section... UNITED STATES AIDS TO NAVIGATION SYSTEM The U.S. Aids to Navigation System § 62.23 Beacons and buoys. (a... navigation. The primary components of the U.S. Aids to Navigation System are beacons and buoys. (b)...

  11. 14 CFR 171.269 - Marker beacon performance requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Marker beacon performance requirements. 171.269 Section 171.269 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Landing System (ISMLS) § 171.269 Marker beacon performance requirements. ISMLS marker beacon...

  12. 33 CFR 62.23 - Beacons and buoys.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Beacons and buoys. 62.23 Section... UNITED STATES AIDS TO NAVIGATION SYSTEM The U.S. Aids to Navigation System § 62.23 Beacons and buoys. (a... navigation. The primary components of the U.S. Aids to Navigation System are beacons and buoys. (b)...

  13. 14 CFR 171.269 - Marker beacon performance requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Marker beacon performance requirements. 171.269 Section 171.269 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Landing System (ISMLS) § 171.269 Marker beacon performance requirements. ISMLS marker beacon...

  14. 14 CFR 171.269 - Marker beacon performance requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Marker beacon performance requirements. 171.269 Section 171.269 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Landing System (ISMLS) § 171.269 Marker beacon performance requirements. ISMLS marker beacon...

  15. 33 CFR 62.23 - Beacons and buoys.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Beacons and buoys. 62.23 Section... UNITED STATES AIDS TO NAVIGATION SYSTEM The U.S. Aids to Navigation System § 62.23 Beacons and buoys. (a... navigation. The primary components of the U.S. Aids to Navigation System are beacons and buoys. (b)...

  16. 33 CFR 62.23 - Beacons and buoys.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Beacons and buoys. 62.23 Section... UNITED STATES AIDS TO NAVIGATION SYSTEM The U.S. Aids to Navigation System § 62.23 Beacons and buoys. (a... navigation. The primary components of the U.S. Aids to Navigation System are beacons and buoys. (b)...

  17. 14 CFR 171.269 - Marker beacon performance requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Marker beacon performance requirements. 171.269 Section 171.269 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Landing System (ISMLS) § 171.269 Marker beacon performance requirements. ISMLS marker beacon...

  18. An aptamer beacon responsive to botulinum toxins.

    PubMed

    Bruno, John G; Richarte, Alicia M; Carrillo, Maria P; Edge, Allison

    2012-01-15

    Sixty candidate DNA aptamers were developed against botulinum neurotoxin (BoNT) type A light chain (LC) from ten rounds of selection, resulting in several identical sequences. Secondary structures of the identical aptamers were compared to structures of previously reported BoNT A DNA aptamers. A series of ten candidate loop structures were selected from this comparison as potential binding pockets and aptamer beacons. These candidate beacons were synthesized with 5'-TYE 665 and 3'-Iowa Black quencher labels for comparison of fluorescence levels as a function of BoNT A LC concentration. Only three of the ten candidates exhibited any fluorescence response to increasing levels of BoNT A LC. However, of the two most responsive candidates, one represented a subset loop of the larger more intensely fluorescent double-looped structure, designated Beacon 10. This beacon yielded a lower limit of detection of 1 ng/mL in buffer using a spectrofluorometer and a portable handheld fluorometer, but also responded substantially to BoNT A, B, E holotoxins and heavy or light chain components even in a dilute soil suspension, but not in 50% human serum. Beacon 10 did not respond strongly to a variety of other divergent peptides, suggesting that it is relatively specific to the level of botulinum toxins and is only useful for environmental testing. Beacon 10 also shared short sequence segments with other published BoNT aptamer DNA sequences, suggesting that these may be points of physical contact between the aptamers and BoNTs.

  19. The Los Alamos beacon receiver array

    SciTech Connect

    Carlos, R.C.; Massey, R.S. )

    1994-07-01

    The authors are interested in studying both the natural background of acoustic and acoustic-gravity waves, for which the sources are not generally known, as well as waves produced by known sources such as large explosions and launches of large rockets. The authors describe radio receivers that monitor transmissions from beacons on geosynchronous satellites. The receivers can detect perturbations of a 300--3,000 s period in the electron density integrated from beacon to receiver, for amplitudes as low as (1--2) [times] 10[sup 13] m[sup [minus]2]. Data are used in studies of atmospheric acoustic and acoustic-gravity waves.

  20. Photomultiplier reception of satellite beacon flashes.

    PubMed

    Abby, D G; Wirtanen, T E

    1969-03-01

    Experiments have been performed on the electrooptical detection of flashes from satellite-borne beacons for the purposes of establishing the time of flash at the observing site, measurement of received pulse shape, and relative measurement of received energy. Initial observations have been made of the beacons carried by the geodetic satellite GEOS-B. Time of flash has been obtained to a precision of 0.1 msec. Pulse shape and energy measurements have been made for various slant ranges and at various voltages on the photomultiplier circuits. Continued testing is directed toward microsecond timing of flash reception.

  1. DNAzyme amplification of molecular beacon signal.

    PubMed

    Tian, Ye; Mao, Chengde

    2005-09-15

    This paper reports an improved catalytic molecular beacon. Addition of the target oligonucleotide activates a DNA enzyme (DNAzyme), which, in turn, activates multiple copies of molecular beacons (MB) and gives rise to a strong fluorescence signal. In a previous design, the activated DNAzyme could oligomerize, especially dimerize, and result in inactivation of the DNAzyme. The current design avoids this problem, upon activated by the target DNA, the DNAzyme will stay constantly active. With the improved method, a detection of 10pM DNA has been demonstrated, which is 1000 times more sensitive than the method previously reported.

  2. Optimized linkage and quenching strategies for quantum dot molecular beacons.

    PubMed

    Cady, Nathaniel C; Strickland, Aaron D; Batt, Carl A

    2007-04-01

    Quantum dot (QD) molecular beacons were explored for sequence-specific DNA detection. The effectiveness of multiple linkage strategies and fluorescence quenchers were compared in hybridization-based assays. To compare linkage strategies, covalent amide linkage and streptavidin-biotin binding were used to link semiconductor QDs to molecular beacon DNA. Amide-linked beacons showed a 57% greater fluorescence increase than streptavidin-linked beacons when hybridized to 200 pmol of target DNA. The specificity of the molecular beacons, however, was similar for both linkage methods. Hybridization of both QD molecular beacons with non-complementary target DNA resulted in approximately 50% lower fluorescence intensity than hybridization with complementary DNA. The effectiveness of different quencher moieties was also evaluated. Iowa Black and 1.4 nm Nanogold-quenched molecular beacons exhibited approximately 2-fold greater fluorescence increases than dabcyl-quenched beacons when hybridized to complementary target. Specificity for target DNA was also confirmed through hybridization assays with non-complementary DNA. To provide insight into differences between the QD molecular beacons and the linkage strategies used, the hydrodynamic radius of each was measured. These measurements indicated that the larger radius of the streptavidin QDs (13.5 nm) than the carboxyl QDs (7 nm) could have a negative effect on FRET-based quenching for QD molecular beacons. These data outline the importance of choosing proper linkage methods and quencher moieties for creating high-quality QD molecular beacons.

  3. Evaluation of Skylab earth laser beacon imagery. [spaceborne photography

    NASA Technical Reports Server (NTRS)

    Piech, K. R.; Schott, J. R.

    1975-01-01

    During the Skylab 3 and 4 missions the Skylab spacecraft was illuminated by a low power argon ion and dye laser. The earth laser beacon was studied visually by the astronauts. In addition, they collected 35 mm hand-held color photographs of the beacons. Photographs are shown that were obtained on Skylab 3 and Skylab 4. The imagery collected during the Skylab mission was analyzed to evaluate the utility of beacon lasers as terrestial 'artificial stars' for space navigation. The analyses of the imagery revealed two unusual features of the earth laser beacon: (1) The beacon, even though of a low power (approximately 1 watt), is considerably brighter than any other terrain feature and is readily visible on imagery at a distance in excess of 1500 km (900 miles). (2) Another feature of the beacon is its large size. The typical beacon extends over about 5 resolution areas with a characteristic dimension of about 200 m.

  4. Aptamer beacons for the direct detection of proteins.

    PubMed

    Hamaguchi, N; Ellington, A; Stanton, M

    2001-07-15

    We have designed a new class of molecules, which we term aptamer beacons, for detecting a wide range of ligands. Similar to molecular beacons, aptamer beacons can adopt two or more conformations, one of which allows ligand binding. A fluorescence-quenching pair is used to report changes in conformation induced by ligand binding. An anti-thrombin aptamer was engineered into an aptamer beacon by adding nucleotides to the 5'-end which are complementary to nucleotides at the 3'-end of the aptamer. In the absence of thrombin, the added nucleotides will form a duplex with the 3'-end, forcing the aptamer beacon into a stem-loop structure. In the presence of thrombin, the aptamer beacon forms the ligand-binding structure. This conformational change causes a change in the distance between a fluorophore attached to the 5'-end and a quencher attached to the 3'-end. Aptamer beacon can be a sensitive tool for detecting proteins and other chemical compounds.

  5. Beacon interacts with cdc2/cdc28-like kinases.

    PubMed

    Kantham, Lakshmi; Kerr-Bayles, Lyndal; Godde, Nathan; Quick, Melissa; Webb, Ryan; Sunderland, Terry; Bond, Judy; Walder, Ken; Augert, Guy; Collier, Greg

    2003-04-25

    Previously we found elevated beacon gene expression in the hypothalamus of obese Psammomys obesus. Beacon administration into the lateral ventricle of P. obesus stimulated food intake and body weight gain. In the current study we used yeast two-hybrid technology to screen for proteins in the human brain that interact with beacon. CLK4, an isoform of cdc2/cdc28-like kinase family of proteins, was identified as a strong interacting partner for beacon. Using active recombinant proteins and a surface plasmon resonance based detection technique, we demonstrated that the three members of this subfamily of kinases (CLK1, 2, and 4) all interact with beacon. Based on the known sequence and functional properties of beacon and CLKs, we speculate that beacon could either modulate the function of key regulatory molecules such as PTP1B or control the expression patterns of specific genes involved in the central regulation of energy metabolism.

  6. Beacon Spacecraft Operations: Lessons in Automation

    NASA Technical Reports Server (NTRS)

    Sherwood, R.; Schlutsmeyer, A.; Sue, M.; Szijjarto, J.; Wyatt, E. J.

    2000-01-01

    A new approach to mission operations has been flight validated on NASA's Deep Space One (DS1) mission that launched in October 1998. The beacon monitor operations technology is aimed at decreasing the total volume of downlinked engineering telemetry by reducing the frequency of downlink and the volume of data received per pass.

  7. Distribution of beacon immunoreactivity in the rat brain.

    PubMed

    Wang, Fei; Tian, De-Run; Tian, Nan; Chen, Hui; Shi, Yu-Shun; Chang, Jaw-Kang; Yang, Jun; Yuan, Lan; Han, Ji-Sheng

    2006-01-01

    Beacon is a novel peptide isolated from the hypothalamus of Israeli sand rat. In the present study, we determined the distribution of beacon in the rat brain using immunohistochemical approach with a polyclonal antiserum directed against the synthetic C-terminal peptide fragment (47-73). The hypothalamus represented the major site of beacon-immunoreactive (IR) cell bodies that were concentrated in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON). Additional immunostained cells were found in the septum, bed nucleus of the stria terminalis, subfornical organ and subcommissural organ. Beacon-IR fibers were seen with high density in the internal layer of the median eminence and low to moderate density in the external layer. Significant beacon-IR fibers were also seen in the nucleus of the solitary tract and lateral reticular formation. The beacon neurons found in the PVN were further characterized by double label immunohistochemistry. Several beacon-IR neurons that resided in the medial PVN were shown to coexpress corticotrophin-releasing hormone (CRH) and most labeled beacon fibers in the external layer of median eminence coexist with CRH. The topographical distribution of beacon-IR in the brain suggests multiple biological activities for beacon in addition to its proposed roles in modulating feeding behaviors and pituitary hormone release.

  8. Antarctic field tests of SARSAT personal locater beacons

    NASA Technical Reports Server (NTRS)

    Bindschadler, Robert

    1987-01-01

    Field tests of SARSAT personal locater beacons were conducted in the Antarctic to assess the viability of using these beacons to increase the safety of Antarctic field parties. Data were collected on the extent to which dry or wet snow, melting conditions, crevasse walls and snow bridges affected the ability of the SARSAT satellite to calculate an accurate position of the beacon. Average response time between beacon turn on and alert reception in McMurdo was between 4 and 5 hours for these tests. It is concluded that the SARSAT system is viable for Antarctic operations and it is recommended that it be implemented for future field operations. Because of obstruction of line-of-sight between beacon and satellite degrades the accuracy of the location calculation (particularly in wet snow), it is further recommended that field parties have sufficient numbers of beacons to insure that in an emergency, one will be able to operate from the surface.

  9. Localization with a mobile beacon in underwater acoustic sensor networks.

    PubMed

    Lee, Sangho; Kim, Kiseon

    2012-01-01

    Localization is one of the most important issues associated with underwater acoustic sensor networks, especially when sensor nodes are randomly deployed. Given that it is difficult to deploy beacon nodes at predetermined locations, localization schemes with a mobile beacon on the sea surface or along the planned path are inherently convenient, accurate, and energy-efficient. In this paper, we propose a new range-free Localization with a Mobile Beacon (LoMoB). The mobile beacon periodically broadcasts a beacon message containing its location. Sensor nodes are individually localized by passively receiving the beacon messages without inter-node communications. For location estimation, a set of potential locations are obtained as candidates for a node's location and then the node's location is determined through the weighted mean of all the potential locations with the weights computed based on residuals.

  10. Privacy Risks from Genomic Data-Sharing Beacons.

    PubMed

    Shringarpure, Suyash S; Bustamante, Carlos D

    2015-11-01

    The human genetics community needs robust protocols that enable secure sharing of genomic data from participants in genetic research. Beacons are web servers that answer allele-presence queries--such as "Do you have a genome that has a specific nucleotide (e.g., A) at a specific genomic position (e.g., position 11,272 on chromosome 1)?"--with either "yes" or "no." Here, we show that individuals in a beacon are susceptible to re-identification even if the only data shared include presence or absence information about alleles in a beacon. Specifically, we propose a likelihood-ratio test of whether a given individual is present in a given genetic beacon. Our test is not dependent on allele frequencies and is the most powerful test for a specified false-positive rate. Through simulations, we showed that in a beacon with 1,000 individuals, re-identification is possible with just 5,000 queries. Relatives can also be identified in the beacon. Re-identification is possible even in the presence of sequencing errors and variant-calling differences. In a beacon constructed with 65 European individuals from the 1000 Genomes Project, we demonstrated that it is possible to detect membership in the beacon with just 250 SNPs. With just 1,000 SNP queries, we were able to detect the presence of an individual genome from the Personal Genome Project in an existing beacon. Our results show that beacons can disclose membership and implied phenotypic information about participants and do not protect privacy a priori. We discuss risk mitigation through policies and standards such as not allowing anonymous pings of genetic beacons and requiring minimum beacon sizes.

  11. Privacy Risks from Genomic Data-Sharing Beacons

    PubMed Central

    Shringarpure, Suyash S.; Bustamante, Carlos D.

    2015-01-01

    The human genetics community needs robust protocols that enable secure sharing of genomic data from participants in genetic research. Beacons are web servers that answer allele-presence queries—such as “Do you have a genome that has a specific nucleotide (e.g., A) at a specific genomic position (e.g., position 11,272 on chromosome 1)?”—with either “yes” or “no.” Here, we show that individuals in a beacon are susceptible to re-identification even if the only data shared include presence or absence information about alleles in a beacon. Specifically, we propose a likelihood-ratio test of whether a given individual is present in a given genetic beacon. Our test is not dependent on allele frequencies and is the most powerful test for a specified false-positive rate. Through simulations, we showed that in a beacon with 1,000 individuals, re-identification is possible with just 5,000 queries. Relatives can also be identified in the beacon. Re-identification is possible even in the presence of sequencing errors and variant-calling differences. In a beacon constructed with 65 European individuals from the 1000 Genomes Project, we demonstrated that it is possible to detect membership in the beacon with just 250 SNPs. With just 1,000 SNP queries, we were able to detect the presence of an individual genome from the Personal Genome Project in an existing beacon. Our results show that beacons can disclose membership and implied phenotypic information about participants and do not protect privacy a priori. We discuss risk mitigation through policies and standards such as not allowing anonymous pings of genetic beacons and requiring minimum beacon sizes. PMID:26522470

  12. Experimental demonstration of atmospheric compensation using multiple synthetic beacons.

    PubMed

    Murphy, D V; Primmerman, C A; Zollars, B G; Barclay, H T

    1991-11-15

    We present experimental results that demonstrate real-time, atmospheric-turbulence compensation of a bright star with the use of two synthetic beacons. Each beacon was used to measure the phase aberrations over only part of the telescope aperture, a configuration that is suitable for reducing focal-anisoplanatism error. To our knowledge, this is the first demonstration of atmospheric compensation with the use of multiple synthetic beacons.

  13. Validation of the Calypso Surface Beacon Transponder.

    PubMed

    Belanger, Maxwell; Saleh, Ziad; Volpe, Tom; Margiasso, Rich; Li, Xiang; Chan, Maria; Zhu, Xiaofeng; Tang, Xiaoli

    2016-01-01

    Calypso L-shaped Surface Beacon transponder has recently become available for clinical applications. We herein conduct studies to validate the Surface Beacon transponder in terms of stability, reproducibility, orientation sensitivity, cycle rate dependence, and respiratory waveform tracking accuracy. The Surface Beacon was placed on a Quasar respiratory phantom and positioned at the isocenter with its two arms aligned with the lasers. Breathing waveforms were simulated, and the motion of the transponder was tracked. Stability and drift analysis: sinusoidal waveforms (200 cycles) were produced, and the amplitudes of phases 0% (inhale) and 50% (exhale) were recorded at each breathing cycle. The mean and standard deviation (SD) of the amplitudes were calculated. Linear least-squares fitting was performed to access the possible amplitude drift over the breathing cycles. Reproducibility: similar setting to stability and drift analysis, and the phantom generated 100 cycles of the sinusoidal waveform per run. The Calypso system's was re-setup for each run. Recorded amplitude and SD of 0% and 50% phase were compared between runs to assess contribution of Calypso electromagnetic array setup variation. Beacon orientation sensitivity: the Calypso tracks sinusoidal phantom motion with a defined angular offset of the beacon to assess its effect on SD and peak-to-peak amplitude. Rate dependence: sinusoidal motion was generated at cycle rates of 1 Hz, .33 Hz, and .2 Hz. Peak-to-peak displacement and SDs were assessed. Respiratory waveform tracking accuracy: the phantom reproduced recorded breathing cycles (by volunteers and patients) were tracked by the Calypso system. Deviation in tracking position from produced waveform was used to calculate SD throughout entire breathing cycle. Stability and drift analysis: Mean amplitude ± SD of phase 0% or 50% were 20.01 ± 0.04 mm and -19.65 ± 0.08 mm, respectively. No clinically significant drift was detected with drift measured as 5.1

  14. Validation of the Calypso Surface Beacon Transponder.

    PubMed

    Belanger, Maxwell; Saleh, Ziad; Volpe, Tom; Margiasso, Rich; Li, Xiang; Chan, Maria; Zhu, Xiaofeng; Tang, Xiaoli

    2016-07-08

    Calypso L-shaped Surface Beacon transponder has recently become available for clinical applications. We herein conduct studies to validate the Surface Beacon transponder in terms of stability, reproducibility, orientation sensitivity, cycle rate dependence, and respiratory waveform tracking accuracy. The Surface Beacon was placed on a Quasar respiratory phantom and positioned at the isocenter with its two arms aligned with the lasers. Breathing waveforms were simulated, and the motion of the transponder was tracked. Stability and drift analysis: sinusoidal waveforms (200 cycles) were produced, and the amplitudes of phases 0% (inhale) and 50% (exhale) were recorded at each breathing cycle. The mean and standard deviation (SD) of the amplitudes were calculated. Linear least-squares fitting was performed to access the possible amplitude drift over the breathing cycles. Reproducibility: similar setting to stability and drift analysis, and the phantom generated 100 cycles of the sinusoidal waveform per run. The Calypso system's was re-setup for each run. Recorded amplitude and SD of 0% and 50% phase were compared between runs to assess contribution of Calypso electromagnetic array setup variation. Beacon orientation sensitivity: the Calypso tracks sinusoidal phantom motion with a defined angular offset of the beacon to assess its effect on SD and peak-to-peak amplitude. Rate dependence: sinusoidal motion was generated at cycle rates of 1 Hz, .33 Hz, and .2 Hz. Peak-to-peak displacement and SDs were assessed. Respiratory waveform tracking accuracy: the phantom reproduced recorded breathing cycles (by volunteers and patients) were tracked by the Calypso system. Deviation in tracking position from produced waveform was used to calculate SD throughout entire breathing cycle. Stability and drift analysis: Mean amplitude ± SD of phase 0% or 50% were 20.01 ± 0.04 mm and -19.65 ± 0.08 mm, respectively. No clinically significant drift was detected with drift measured as 5.1

  15. Development of a universal RNA beacon for exogenous gene detection.

    PubMed

    Guo, Yuanjian; Lu, Zhongju; Cohen, Ira Stephen; Scarlata, Suzanne

    2015-05-01

    Stem cell therapy requires a nontoxic and high-throughput method to achieve a pure cell population to prevent teratomas that can occur if even one cell in the implant has not been transformed. A promising method to detect and separate cells expressing a particular gene is RNA beacon technology. However, developing a successful, specific beacon to a particular transfected gene can take months to develop and in some cases is impossible. Here, we report on an off-the-shelf universal beacon that decreases the time and cost of applying beacon technology to select any living cell population transfected with an exogenous gene.

  16. Development of a Universal RNA Beacon for Exogenous Gene Detection

    PubMed Central

    Guo, Yuanjian; Lu, Zhongju; Cohen, Ira Stephen

    2015-01-01

    Stem cell therapy requires a nontoxic and high-throughput method to achieve a pure cell population to prevent teratomas that can occur if even one cell in the implant has not been transformed. A promising method to detect and separate cells expressing a particular gene is RNA beacon technology. However, developing a successful, specific beacon to a particular transfected gene can take months to develop and in some cases is impossible. Here, we report on an off-the-shelf universal beacon that decreases the time and cost of applying beacon technology to select any living cell population transfected with an exogenous gene. PMID:25769653

  17. Killer beacons for combined cancer imaging and therapy.

    PubMed

    Stefflova, Klara; Chen, Juan; Zheng, Gang

    2007-01-01

    Precisely localizing therapeutic agents in neoplastic areas would greatly improve their efficacy for killing tumor cells and reduce their toxicity to normal cells. Photodynamic therapy (PDT) is a promising cancer treatment modality, and near-infrared fluorescence imaging (NIRF-I) is a sensitive and noninvasive approach for in vivo cancer detection. This review focuses on the current efforts to engineer single molecule constructs that allow these two modalities to be combined to achieve a high level of selectivity for cancer treatment. The primary component of these so called killer beacons is a fluorescent photosensitizer responsible for both imaging and therapy. By attaching other components, e.g. various DNA- or peptide-based linkers, quenchers or cancer cell-specific delivery vehicles, their primary diagnostic and therapeutic functions as well as their target specificity and pharmacological properties can be modulated. This modular design makes these agents customizable, offering the ability to assemble a few simple and often interchangeable functional modules into beacons with totally different functions. This review will summarize following three types of killer beacons: photodynamic molecular beacons, traceable beacons and beacons with built-in apoptosis sensor. Despite the rapid progress in killer beacon development, numerous challenges remain before these beacons can be translated into clinics, such as photobleaching, delivery efficiency and cancer-specificity. In this review we outline the basic principles of killer beacons, the current achievements and future directions, including possible cancer targets and different therapeutic applications.

  18. Portable-Beacon Landing System for Helicopters

    NASA Technical Reports Server (NTRS)

    Davis, Thomas J.; Clary, George R.; Chisholm, John P.; Macdonald, Stanley L.

    1987-01-01

    Prototype beacon landing system (BLS) allows helicopters to make precise landings in all weather. BLS easily added to existing helicopter avionic equipment and readily deployed at remote sites. Small and light, system employs X-band radar and digital processing. Variety of beams pulsed sequentially by ground station after initial interrogation by weather radar of approaching helicopter. Airborne microprocessor processes pulses to determine glide slope, course deviation, and range.

  19. Experience with the BEACON core monitoring system

    SciTech Connect

    Beard, C.L. ); Icide, C.A. )

    1992-01-01

    The BEACON operational core support system was developed for use in pressurized water reactors to provide an integrated system to perform reactor core monitoring, core measurement reduction, core analysis and follow, and core predictions. It is based on the very fast and accurate three-dimensional SPNOVA nodal program. The experience to date has shown the importance of an accurate integrated system. The benefits accrued are greater for the total system than the benefits that are possible separately.

  20. Activation kinetics of zipper molecular beacons.

    PubMed

    Liu, Tracy W; Chen, Juan; Burgess, Laura; Wilson, Brian C; Zheng, Gang; Zhan, Lixin; Liu, Wing-Ki; Ha, Bae-Yeun

    2015-01-01

    Proteases play key roles in the regulation of normal cellular function, and thus, their deregulation leads to many disease states. Molecular beacons are promising protease-imaging probes for the detection and characterization of disease as well as for the evaluation of treatment. Inspired by this, we examined the efficiency of zipper molecular beacons (ZMBs) as imaging probes. First, we showed experimentally that the symmetrical ZMB (zip5e5r), bearing 5-arginine and 5-glutamate arms, is as efficient as the asymmetrical zip5e8r in enhancing cell uptake but without the dark toxicity exhibited by the asymmetric zipper. Also, zip5e5r was shown to dissociate more efficiently at pH’s greater than 5. Using a simple two-state binding model, we attributed this to a larger number of charge-pair conformations for zip5e8r. We then measured the ability of soluble matrix metalloproteinases (MMPs) to cleave zip5e5r, and compared their cleavage efficiency with the original photodynamic molecular beacon (PMB). Finally, as a first step toward understanding our observations quantitatively, we simulated the native structures of the peptides GPLGLARK and EGPLGLARRK with charged termini NH3(+) and COO(-) that approximate the PMB and ZMB (with one pair of arginine/glutamate electrostatic zipper), respectively. We concluded that inclusion of the zipper changes the native structure of the MBs, altering the cleavage efficiency of different MMPs.

  1. Beacon immunoreactivity in the rat hypothalamus.

    PubMed

    Ng, Y K; Brailoiu, G C; Dun, S L; Ling, E A; Yang, J; Chang, J K; Dun, N J

    2006-05-01

    Beacon (BC) is a peptide of 73 amino acids, whose gene expression was first reported in the hypothalamus of Psammomys obesus (or Israeli sand rat). To appreciate better the functional role of BC in normal rats and sand rats, the distribution of BC immunoreactivity (irBC) and its subcellular localization were studied in the brain of Sprague-Dawley rats. In the hypothalamus, intense staining was present in neurons of the supraoptic (SO), paraventricular (PVH), and accessory neurosecretory nuclei and in cell processes of median eminence. Double labeling of the hypothalamic sections with mouse monoclonal oxytocin (OT) antibody and rabbit polyclonal BC antiserum revealed that nearly all OT-immunoreactive cells from SO, PVH, and accessory neurosecretory nuclei were irBC. Double labeling of the sections with guinea pig vasopressin (VP) antiserum and BC antiserum showed that a population of VP-immunoreactive neurons was irBC. By immunoelectron microscopy, immunoreactive product was associated with mitochondrial membranes or appeared as electron-dense bodies in many PVH and SO neurons. Most of the neurosecretory granules were unstained for BC. Taken together, our results indicate the presence of beacon in the OT-containing neurons and a population of VP-containing neurons, mostly associated with mitochondrial membrane. Insofar as the amino acids sequence of beacon is identical to that of ubiquitin-like 5, it is possible that the distribution of BC immunoreactivity noted in our study is that of ubiquitin-like 5 peptide in the rat hypothalamus.

  2. 54. DETAIL OF GENERAL ELECTRIC AIRBORNE BEACON EQUIPMENT TEST SET ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. DETAIL OF GENERAL ELECTRIC AIRBORNE BEACON EQUIPMENT TEST SET (LEFT) AND ASSOCIATED GOULD BRUSH CHART RECORDERS (RIGHT). ELAPSED TIME COUNTER SITS ATOP AIRBORNE BEACON EQUIPMENT TEST SET. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  3. Beacons In Brief. P/PV In Brief. Issue 2

    ERIC Educational Resources Information Center

    Blank, Susan; Farley, Chelsea

    2004-01-01

    This second issue in P/PV's "In Brief" series focuses on the San Francisco Beacon Initiative and P/PV's recently released evaluation results. The Beacon Initiative established after-school programs in eight public schools in low-income San Francisco neighborhoods. P/PV's 36-month evaluation examined key developmental and academic outcomes.…

  4. Evaluation of the New York City Beacons. Phase I Findings.

    ERIC Educational Resources Information Center

    Warren, Constancia; Brown, Prudence; Freudenberg, Nicholas

    This report presents findings from Phase 1 of an evaluation of the New York City Beacons initiative, a school-community-family partnership model initiated in 1991. Beacons are community centers within public schools that offer activities and services to people of all ages before and after school, in the evenings, and on weekends. Research included…

  5. Enzymatic signal amplification of molecular beacons for sensitive DNA detection.

    PubMed

    Li, Jianwei Jeffery; Chu, Yizhuo; Lee, Benjamin Yi-Hung; Xie, Xiaoliang Sunney

    2008-04-01

    Molecular beacons represent a new family of fluorescent probes for nucleic acids, and have found broad applications in recent years due to their unique advantages over traditional probes. Detection of nucleic acids using molecular beacons has been based on hybridization between target molecules and molecular beacons in a 1:1 stoichiometric ratio. The stoichiometric hybridization, however, puts an intrinsic limitation on detection sensitivity, because one target molecule converts only one beacon molecule to its fluorescent form. To increase the detection sensitivity, a conventional strategy has been target amplification through polymerase chain reaction. Instead of target amplification, here we introduce a scheme of signal amplification, nicking enzyme signal amplification, to increase the detection sensitivity of molecular beacons. The mechanism of the signal amplification lies in target-dependent cleavage of molecular beacons by a DNA nicking enzyme, through which one target DNA can open many beacon molecules, giving rise to amplification of fluorescent signal. Our results indicate that one target DNA leads to cleavage of hundreds of beacon molecules, increasing detection sensitivity by nearly three orders of magnitude. We designed two versions of signal amplification. The basic version, though simple, requires that nicking enzyme recognition sequence be present in the target DNA. The extended version allows detection of target of any sequence by incorporating rolling circle amplification. Moreover, the extended version provides one additional level of signal amplification, bringing the detection limit down to tens of femtomolar, nearly five orders of magnitude lower than that of conventional hybridization assay.

  6. Multiplex detection of single-nucleotide variations using molecular beacons.

    PubMed

    Marras, S A; Kramer, F R; Tyagi, S

    1999-02-01

    We demonstrate that single-nucleotide differences in a DNA sequence can be detected in homogeneous assays using molecular beacons. In this method, the region surrounding the site of a sequence variation is amplified in a polymerase chain reaction and the identity of the variant nucleotide is determined by observing which of four differently colored molecular beacons binds to the amplification product. Each of the molecular beacons is perfectly complementary to one variant of the target sequence and each is labeled with a different fluorophore. To demonstrate the specificity of these assays, we prepared four template DNAs that only differed from one another by the identity of the nucleotide at one position. Four amplification reactions were prepared, each containing all four molecular beacons, but each initiated with only one of the four template DNAs. The results show that in each reaction a fluorogenic response was elicited from the molecular beacon that was perfectly complementary to the amplified DNA, but not from the three molecular beacons whose probe sequence mismatched the target sequence. The color of the fluorescence that appeared in each tube during the course of the amplification indicated which nucleotide was present at the site of variation. These results demonstrate the extraordinary specificity of molecular beacons. Furthermore, the results illustrate how the ability to label molecular beacons with differently colored fluorophores enables simple multiplex assays to be carried out for genetic analysis.

  7. A search for optical beacons: implications of null results.

    PubMed

    Blair, David G; Zadnik, Marjan G

    2002-01-01

    Over the past few years a series of searches for interstellar radio beacons have taken place using the Parkes radio telescope. Here we report hitherto unpublished results from a search for optical beacons from 60 solar-type stars using the Perth-Lowell telescope. We discuss the significance of the null results from these searches, all of which were based on the interstellar contact channel hypothesis. While the null results of all searches to date can be explained simply by the nonexistence of electromagnetically communicating life elsewhere in the Milky Way, four other possible explanations that do not preclude its existence are proposed: (1) Extraterrestrial civilizations desiring to make contact through the use of electromagnetic beacons have a very low density in the Milky Way. (2) The interstellar contact channel hypothesis is incorrect, and beacons exist at frequencies that have not yet been searched. (3) The search has been incomplete in terms of sensitivity and/or target directions: Beacons exist, but more sensitive equipment and/or more searching is needed to achieve success. (4) The search has occurred before beacon signals can be expected to have arrived at the Earth, and beacon signals may be expected in the future. Based on consideration of the technology required for extraterrestrial civilizations to identify target planets, we argue that the fourth possibility is likely to be valid and that powerful, easily detectable beacons could be received in coming centuries.

  8. A search for optical beacons: implications of null results.

    PubMed

    Blair, David G; Zadnik, Marjan G

    2002-01-01

    Over the past few years a series of searches for interstellar radio beacons have taken place using the Parkes radio telescope. Here we report hitherto unpublished results from a search for optical beacons from 60 solar-type stars using the Perth-Lowell telescope. We discuss the significance of the null results from these searches, all of which were based on the interstellar contact channel hypothesis. While the null results of all searches to date can be explained simply by the nonexistence of electromagnetically communicating life elsewhere in the Milky Way, four other possible explanations that do not preclude its existence are proposed: (1) Extraterrestrial civilizations desiring to make contact through the use of electromagnetic beacons have a very low density in the Milky Way. (2) The interstellar contact channel hypothesis is incorrect, and beacons exist at frequencies that have not yet been searched. (3) The search has been incomplete in terms of sensitivity and/or target directions: Beacons exist, but more sensitive equipment and/or more searching is needed to achieve success. (4) The search has occurred before beacon signals can be expected to have arrived at the Earth, and beacon signals may be expected in the future. Based on consideration of the technology required for extraterrestrial civilizations to identify target planets, we argue that the fourth possibility is likely to be valid and that powerful, easily detectable beacons could be received in coming centuries. PMID:12530240

  9. Molecular beacons as probes of RNA unfolding under native conditions.

    PubMed

    Hopkins, Julia F; Woodson, Sarah A

    2005-01-01

    Hybridization of fluorescent molecular beacons provides real-time detection of RNA secondary structure with high specificity. We used molecular beacons to measure folding and unfolding rates of the Tetrahymena group I ribozyme under native conditions. A molecular beacon targeted against 15 nt in the 5' strand of the P3 helix specifically hybridized with misfolded forms of the ribozyme, without invading the native tertiary structure. The beacon associated with the misfolded ribozyme 300 times more slowly than with an unstructured oligonucleotide containing the same target sequence, suggesting that the misfolded ribozyme core remains structured in the absence of Mg2+. The rate of beacon hybridization under native conditions revealed a linear relationship between the free energy of unfolding and Mg2+ concentration. A small fraction of the RNA population unfolded very rapidly, suggesting parallel unfolding in one step or through misfolded intermediates.

  10. Indoor Navigation using Direction Sensor and Beacons

    NASA Technical Reports Server (NTRS)

    Shields, Joel; Jeganathan, Muthu

    2004-01-01

    A system for indoor navigation of a mobile robot includes (1) modulated infrared beacons at known positions on the walls and ceiling of a room and (2) a cameralike sensor, comprising a wide-angle lens with a position-sensitive photodetector at the focal plane, mounted in a known position and orientation on the robot. The system also includes a computer running special-purpose software that processes the sensor readings to obtain the position and orientation of the robot in all six degrees of freedom in a coordinate system embedded in the room.

  11. Indwelling rumino-reticulum bolus radio beacon.

    PubMed

    Kath, G S; Egerton, J R; Geiger, R

    1985-01-01

    A miniature battery-powered radio beacon attached to a stainless steel bolus housing an osmotic pump is described. When the bolus, of sufficient size and density to be retained in the reticulum, is administered to ruminants the radio signal can be received, using a standard AM broadcast receiver up to a range of 1.5 m. The unit allows making a simple and inexpensive verification that the drug delivery system is still within the rumino-reticulum during long-term drug delivery studies and making an external estimation of the internal anatomic location of the device.

  12. Determining Locations by Use of Networks of Passive Beacons

    NASA Technical Reports Server (NTRS)

    Okino, Clayton; Gray, Andrew; Jennings, Esther

    2009-01-01

    Networks of passive radio beacons spanning moderate-sized terrain areas have been proposed to aid navigation of small robotic aircraft that would be used to explore Saturn s moon Titan. Such networks could also be used on Earth to aid navigation of robotic aircraft, land vehicles, or vessels engaged in exploration or reconnaissance in situations or locations (e.g., underwater locations) in which Global Positioning System (GPS) signals are unreliable or unavailable. Prior to use, it would be necessary to pre-position the beacons at known locations that would be determined by use of one or more precise independent global navigation system(s). Thereafter, while navigating over the area spanned by a given network of passive beacons, an exploratory robot would use the beacons to determine its position precisely relative to the known beacon positions (see figure). If it were necessary for the robot to explore multiple, separated terrain areas spanned by different networks of beacons, the robot could use a long-haul, relatively coarse global navigation system for the lower-precision position determination needed during transit between such areas. The proposed method of precise determination of position of an exploratory robot relative to the positions of passive radio beacons is based partly on the principles of radar and partly on the principles of radio-frequency identification (RFID) tags. The robot would transmit radar-like signals that would be modified and reflected by the passive beacons. The distance to each beacon would be determined from the roundtrip propagation time and/or round-trip phase shift of the signal returning from that beacon. Signals returned from different beacons could be distinguished by means of their RFID characteristics. Alternatively or in addition, the antenna of each beacon could be designed to radiate in a unique pattern that could be identified by the navigation system. Also, alternatively or in addition, sets of identical beacons could

  13. Diagnosis of Neisseria gonorrhoeae using molecular beacon.

    PubMed

    Sachdev, Divya; Patel, Achchhe Lal; Sonkar, Subash Chandra; Kumari, Indu; Saluja, Daman

    2015-01-01

    Neisseria gonorrhoeae is an important sexually transmitted diseases (STD) causing pathogen worldwide. Due to absence of an affordable diagnostic assay, routine screening of gonococcal infection becomes impossible in developing countries where infection rates are maximum. Treatment is given on the basis of symptoms alone which leads to spread of infection. Thus, development of a rapid, sensitive, specific, and PCR based visual diagnostic assay suitable for developing countries, required for better disease management, is aimed at in present study. Endocervical swabs were collected from patients visiting gynecology department of various hospitals in Delhi. In-house PCR based assay was developed and modified to visual assay using molecular beacon for end-point detection. It was evaluated against Roche AMPLICOR NG kit and rmp gene. Specificity of beacon was confirmed by competition experiments. Diagnostic test was 98.21% specific and 99.59% sensitive whereas negative and positive predicted value were 99.40% and 98.78%, respectively. We also observed that twice the concentration (2X) of premix was stable at 4°C for 4 months and dry swab samples gave concordant results with that of wet swabs. These features make the test best suitable for routine diagnosis of genital infections in developing countries.

  14. Using molecular beacons for cancer imaging and treatment.

    PubMed

    Stefflova, Klara; Chen, Juan; Zheng, Gang

    2007-01-01

    Molecular beacons are essentially all probes that illuminate particular cellular target or cells with similar characteristics. In this review we focus on those molecular beacons that use near-infrared fluorescence imaging (NIRF-I) to identify the unique cellular and metabolic markers characteristic of cancer. They employ various delivery and activation pathways, selectively or specifically targeting proliferating and immortal cancer cells. These beacons can either be used in an imaging step separate from therapy or they can intimately connect these two steps into a single process. Matching cancer therapy to NIRF-I is photodynamic therapy (PDT) that uses the light-triggered phototoxic properties of some porphyrin-based dyes. Guided by beacon's restored fluorescence, the PDT laser could be focused on affected sites, killing the cancer cells using the enhanced photoactivity of the same beacon. Or vice versa-the restored fluorescence from the cleaved beacon could be used as an indication of the beacon's own therapeutic success, imaging the post-PDT apoptotic cells.

  15. Molecular Beacon-Based MicroRNA Imaging During Neurogenesis.

    PubMed

    Lee, Jonghwan; Kim, Soonhag

    2016-01-01

    The fluorescence monitoring system for examining endogenous microRNA (miRNA) activity in cellular level provides crucial information on not only understanding a critical role of miRNA involving a variety of biological processes, but also evaluating miRNA expression patterns in a noninvasive manner. In this protocol, we report the details of a new procedure for a molecular beacon-based miRNA monitoring system, which includes the illustration scheme for miRNA detection strategy, exogenous miRNA detection, and measurement of endogenous miRNA expression level during neurogenesis. The fluorescence signal of miR-124a beacon quenched by BHQ2 was gradually recovered as increasing concentration of the miR-124a in tube. The functional work of miR-124a beacon was examined in intracellular environment, allowing for the internalization of the miR-124a beacon by lipofectamine, which resulted in activated fluorescent signals of the miR-124a beacon in the HeLa cells after the addition of synthetic miR-124a. The endogenous miR-124a expression level was detected by miR-124a beacon system during neurogenesis, showing brighter fluorescence intensity in cytoplasmic area of P19 cells after induction of neuronal differentiation by retinoic acid. The molecular beacon based-miRNA detection technique could be applicable to the simultaneous visualization of a variety of miRNA expression patterns using different fluorescence dyes. For the study of examining endogenous miRNA expression level using miRNA-beacon system, if cellular differentiation step is already prepared, transfection step of miR-124a beacon into P19 cells, and acquisition of activated fluorescence signal measured by confocal microscope can be conducted approximately within 6 h.

  16. Do rufous hummingbirds (Selasphorus rufus) use visual beacons?

    PubMed

    Hurly, T Andrew; Franz, Simone; Healy, Susan D

    2010-03-01

    Animals are often assumed to use highly conspicuous features of a goal to head directly to that goal ('beaconing'). In the field it is generally assumed that flowers serve as beacons to guide pollinators. Artificial hummingbird feeders are coloured red to serve a similar function. However, anecdotal reports suggest that hummingbirds return to feeder locations in the absence of the feeder (and thus the beacon). Here we test these reports for the first time in the field, using the natural territories of hummingbirds and manipulating flowers on a scale that is ecologically relevant to the birds. We compared the predictions from two distinct hypotheses as to how hummingbirds might use the visual features of rewards: the distant beacon hypothesis and the local cue hypothesis. In two field experiments, we found no evidence that rufous hummingbirds used a distant visual beacon to guide them to a rewarded location. In no case did birds abandon their approach to the goal location from a distance; rather they demonstrated remarkable accuracy of navigation by approaching to within about 70 cm of a rewarded flower's original location. Proximity varied depending on the size of the training flower: birds flew closer to a previously rewarded location if it had been previously signalled with a small beacon. Additionally, when provided with a beacon at a new location, birds did not fly directly to the new beacon. Taken together, we believe these data demonstrate that these hummingbirds depend little on visual characteristics to beacon to rewarded locations, but rather that they encode surrounding landmarks in order to reach the goal and then use the visual features of the goal as confirmation that they have arrived at the correct location.

  17. High efficiency low cost monolithic module for SARSAT distress beacons

    NASA Technical Reports Server (NTRS)

    Petersen, Wendell C.; Siu, Daniel P.

    1992-01-01

    The program objectives were to develop a highly efficient, low cost RF module for SARSAT beacons; achieve significantly lower battery current drain, amount of heat generated, and size of battery required; utilize MMIC technology to improve efficiency, reliability, packaging, and cost; and provide a technology database for GaAs based UHF RF circuit architectures. Presented in viewgraph form are functional block diagrams of the SARSAT distress beacon and beacon RF module as well as performance goals, schematic diagrams, predicted performances, and measured performances for the phase modulator and power amplifier.

  18. 4. DETAIL, CASTIRON BASE, SOUTH CORNER Mispillion Lighthouse, Beacon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. DETAIL, CAST-IRON BASE, SOUTH CORNER - Mispillion Lighthouse, Beacon Tower, South bank of Mispillion River at it confluence with Delaware River at northeast end of County Road 203, 7 miles east of Milford, Milford, Sussex County, DE

  19. 2. VIEW NORTHWEST, SOUTHEAST FRONT Mispillion Lighthouse, Beacon Tower, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW NORTHWEST, SOUTHEAST FRONT - Mispillion Lighthouse, Beacon Tower, South bank of Mispillion River at it confluence with Delaware River at northeast end of County Road 203, 7 miles east of Milford, Milford, Sussex County, DE

  20. Southeast (front) elevation Mispillion Lighthouse, Beacon Tower, South bank ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Southeast (front) elevation - Mispillion Lighthouse, Beacon Tower, South bank of Mispillion River at it confluence with Delaware River at northeast end of County Road 203, 7 miles east of Milford, Milford, Sussex County, DE

  1. 6. DETAIL, SOUTHEAST FRONT, SECOND STAGE Mispillion Lighthouse, Beacon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. DETAIL, SOUTHEAST FRONT, SECOND STAGE - Mispillion Lighthouse, Beacon Tower, South bank of Mispillion River at it confluence with Delaware River at northeast end of County Road 203, 7 miles east of Milford, Milford, Sussex County, DE

  2. GaAs monolithic RF modules for SARSAT distress beacons

    NASA Technical Reports Server (NTRS)

    Cauley, Michael A.

    1991-01-01

    Monolithic GaAs UHF components for use in SARSAT Emergency Distress beacons are under development by Microwave Monolithics, Inc., Simi Valley, CA. The components include a bi-phase modulator, driver amplifier, and a 5 watt power amplifier.

  3. Optical telecommunications: performance of the qualification model SILEX beacon

    NASA Astrophysics Data System (ADS)

    Renard, Michel; Dobie, Paul J.; Gollier, Jacques; Heinrichs, Theo; Woszczyk, Pawel; Sobeczko, Andre

    1995-04-01

    The Beacon is a powerful non-coherent CW infra-red laser source which is developed under the Semi-conductor Inter-satellite Link Experiment (SILEX). It will provide a high divergence beam used during the first tracking acquisition sequence of the Spot 4/Artemis optical communication link. The Beacon uses high efficiency anamorphic couplers to deliver output from 19 laser diodes into a single multi-mode Mixing Fiber, the exit of which is integrated at the focal plane of a collimator. Beacon output is maintained at the required level during unit life using an Optical Monitoring System and a Beacon output Tele-Command. The Engineering Qualification Model is now complete and overall performance with respect to the SILEX requirements is presented.

  4. Molecular beacons: fluorogenic probes for living cell study.

    PubMed

    Fang, Xiaohong; Mi, Yanming; Li, Jianwei Jeffery; Beck, Terry; Schuster, Sheldon; Tan, Weihong

    2002-01-01

    Molecular beacons are a new class of fluorescent probes that can report the presence of specific nucleic acids with high sensitivity and excellent specificity. In addition to their current wide applications in monitoring the progress of polymerase chain reactions, their unique properties make them promising probes for the detection and visualization of target biomolecules in living cells. This article is focused on our recent research in exploring the potential of using molecular beacon for living-cell studies in three important areas: the monitoring of mRNA in living cells, the development of ultrasmall DNA/RNA biosensors, and the novel approach of combining molecular beacon's signal transduction mechanism with aptamer's specificity for real-time protein detection. These applications demonstrate molecular beacon's unique properties in bioanalysis and bioassay development.

  5. Label-free molecular beacons for biomolecular detection.

    PubMed

    Tan, Xiaohong; Wang, Yi; Armitage, Bruce A; Bruchez, Marcel P

    2014-11-01

    Biomolecular detection and imaging methods provide quantitative measurements essential for biological research. In this context, molecular beacon based sensors have emerged as powerful, no-wash imaging agents, providing target-specific fluorescent activation for nucleic acids, proteins, and small molecules. Conventional molecular beacons require double-labeled DNA sequences, which are costly and time-consuming to prepare. To address this issue, we developed DNA based label-free molecular beacons consisting of two regions: a signal-generating region based on human telomeric G-quadruplex sequence that activates Thioflavin T fluorescence and a target recognition sequence designed to interact in a molecular beacon format. We demonstrated the utility of these probes for the selective detection of DNA, RNA, and protein. Multiple probes were applied against a single target to achieve improved brightness in fluorescence detection of nucleic acid targets. This label-free strategy provides a straightforward, cost-effective alternative to fluorescently labeled oligonucleotides in biomolecular detection and imaging.

  6. Optical telecommunications: expected performance of the beacon

    NASA Astrophysics Data System (ADS)

    Renard, Michel; Gollier, Jacques; Dobie, Paul J.; Heinrichs, Theo; Sobeczko, Andre

    1994-09-01

    The beacon is a powerful non-coherent CW laser source which is developed in the frame of the Semi-conductor Inter-satellite Link Experiment (SILEX). Its functionality is to provide a high divergence beam during the first tracking sequence. It is made up of 19 laser diodes coupled into one multi-mode fiber, the exit face of that fiber being integrated at the focal plane of a collimator. A breadboarding phase has been conducted at the beginning of the phase C/D in order to demonstrate that the requirement of 8 KW/Sr within a divergence of 11.75 mRd will be achieved. That phase is now completed and the overall breadboard performance is discussed in this paper with respect to the SILEX requirements.

  7. Molecular beacons: a novel optical diagnostic tool.

    PubMed

    Han, Su-Xia; Jia, Xi; Ma, Jin-lu; Zhu, Qing

    2013-04-01

    As a result of the efforts of the Human Genome Project and the rise in demand for molecular diagnostic assays, the development and optimization of novel hybridization probes have focused on speed, reliability, and accuracy in the identification of nucleic acids. Molecular beacons (MBs) are single-stranded, fluorophore-labeled nucleic acid probes that are capable of generating a fluorescent signal in the presence of target, but are dark in the absence of target. Because of the high specificity and sensitivity characteristics, MBs have been used in variety of fields. In this review, MBs are introduced and discussed as diagnostic tools in four sections: several technologies of MBs will be illustrated primarily; the limitation of MBs next; the third part is new fashions of MBs; and the last one is to present the application of MBs in disease diagnosis.

  8. Molecular beacons for detecting DNA binding proteins.

    PubMed

    Heyduk, Tomasz; Heyduk, Ewa

    2002-02-01

    We report here a simple, rapid, homogeneous fluorescence assay, the molecular beacon assay, for the detection and quantification of sequence-specific DNA-binding proteins. The central feature of the assay is the protein-dependent association of two DNA fragments each containing about half of a DNA sequence defining a protein-binding site. Protein-dependent association of DNA fragments can be detected by any proximity-based spectroscopic signal, such as fluorescence resonance energy transfer (FRET) between fluorochromes introduced into these DNA molecules. The assay is fully homogeneous and requires no manipulations aside from mixing of the sample and the test solution. It offers flexibility with respect to the mode of signal detection and the fluorescence probe, and is compatible with multicolor simultaneous detection of several proteins. The assay can be used in research and medical diagnosis and for high-throughput screening of drugs targeted to DNA-binding proteins.

  9. Reagentless, reusable, ultrasensitive electrochemical molecular beacon aptasensor.

    PubMed

    Radi, Abd-Elgawad; Acero Sánchez, Josep Lluis; Baldrich, Eva; O'Sullivan, Ciara K

    2006-01-11

    A bifunctional derivative of the thrombin-binding aptamer with a redox-active Fc moiety and a thiol group at the termini of the aptamer strand was synthesized. The ferrocene-labeled aptamer thiol was self-assembled through S-Au bonding on a polycrystalline gold electrode surface and the surface was blocked with 2-mercaptoethanol to form a mixed monolayer. By use of a fluorescent molecular beacon, the effect of counterions on quadruplex formation was established. The aptamer-modified electrode was characterized electrochemically by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The modified electrode showed a voltammetric signal due to a one-step redox reaction of the surface-confined ferrocenyl moiety of the aptamer immobilized on the electrode surface in 10 mM N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (HEPES) buffer of pH 8.0. An increase in the DPV current signal was evident after blocking with 2-mercaptoethanol, effectively removing aptamer nonspecifically absorbed rather than bound to electrode surface or due to the formation of the aptamer-thrombin affinity interaction. The impedance measurement, in agreement with the differential pulse voltammetry (DPV), showed decreased Faradaic resistances in the same sequence. The "signal-on" upon thrombin association could be attributed to a change in conformation from random coil-like configuration on the probe-modified film to the quadruplex structure. The DPV of the modified electrode showed a linear response of the Fc oxidation signal to the increase in the thrombin concentration in the range between 5.0 and 35.0 nM with a linear correlation of r = 0.9988 and a detection limit of 0.5 nM. The molecular beacon aptasensor was amenable to full regeneration by simply unfolding the aptamer in 1.0 M HCl, and could be regenerated 25 times with no loss in electrochemical signal upon subsequent thrombin binding.

  10. Optical telecommunications: performance of the protoflight model SILEX beacon

    NASA Astrophysics Data System (ADS)

    Renard, Michel; Dobie, Paul J.; Grodent, C.; Woszczyk, Pawel; Sobeczko, Andre

    1996-04-01

    The beacon is a powerful non-coherent cw infra-red laser source which will provide a high divergence beam used during the first tracking acquisition sequence of the Spot 4/Artemis optical communication link. The beacon uses high efficiency anamorphic couplers to deliver output from 19 laser diodes into a single multi-mode mixing fiber, the exit of which is integrated at the focal plane of a collimator. Beacon output is maintained at the required level (nominally 8 KW/Sr) during unit life using an optical monitoring system and a beacon output tele-command. Following successful environmental testing, the proto-flight model (PFM) has recently been delivered ready for integration onto the SILEX terminal. This paper describes the overall performance of the PFM beacon with respect to SILEX requirements. An improved beacon using 1.2 W laser diodes which will be capable of delivering up to 17 KW/Sr is currently under construction. An analysis of the design aspects to be considered when using high power laser diodes in this type of application is presented. Finally, a brief summary is given of SPACEBEL activities associated with high power and more compact optical communication units for future missions.

  11. Detection of adenovirus using PCR and molecular beacon.

    PubMed

    Poddar, S K

    1999-09-01

    The polymerase chain reaction (PCR) and a molecular beacon probe were used for the detection of Adenovirus. A 307 bp DNA fragment from a conserved region of the hexon gene was amplified. The specific molecular beacon was characterized with respect to its efficiency of quenching, and signal to noise ratio by spectrofluorometric analysis of its hybridization with virus specific complementary single stranded oligonucleotide target. Amplification was carried out in the presence of the molecular beacon probe, and the amplified target was detected by measurement of fluorescence signal in the post PCR sample. Separately, a 32P-labeled linear probe (having the same sequence as that of molecular beacon probe) was liquid-phase hybridized with the product of PCR performed in the absence of the molecular beacon. The virus specific target was then detected by electrophoresis of the hybridized product in a nondenaturing polyacrylamide gel and subsequent autoradiographic analysis. The detection limit of adenovirus by PCR in the presence of the molecular beacon probe was found to be similar to that obtained by labeled linear probe hybridization following PCR.

  12. Micropatterning of Aptamer Beacons to Create Cytokine-Sensing Surfaces.

    PubMed

    Tuleuova, Nazgul; Revzin, Alexander

    2010-12-01

    Aptamer beacons are DNA or RNA probes that bind proteins or small molecules of interest and emit signal directly upon interaction with the target analyte. This paper describes micropatterning of aptamer beacons for detection of IFN-γ-an important inflammatory cytokine. The beacon consisted of a fluorophore-labeled aptamer strand hybridized with a shorter, quencher-carrying complementary strand. Cytokine molecules were expected to displace quenching strands of the beacon, disrupting FRET effect and resulting in fluorescence signal. The glass substrate was first micropatterned with poly(ethylene glycol) (PEG) hydrogel microwells (35 μm diameter individual wells) so as to define sites for attachment of beacon molecules. PEG microwell arrays were then incubated with avidin followed by biotin-aptamer-fluorophore constructs. Subsequent incubation with quencher-carrying complementary strands resulted in formation of DNA duplex and caused quenching of fluorescence due to FRET effect. When exposed to IFN-γ, microwells changed fluorescence from low (quencher hybridized with fluorophore-carrying strand) to high (quenching strand displaced by cytokine molecules). The fluorescence signal was confined to microwells, was changing in real-time and was dependent on the concentration of IFN-γ. In the future, we plan to co-localize aptamer beacons and cells on micropatterned surfaces in order to monitor in real-time cytokine secretion from immune cells in microwells.

  13. Kinetic optimization of a protein-responsive aptamer beacon.

    PubMed

    Hall, Bradley; Cater, Sean; Levy, Matt; Ellington, Andrew D

    2009-08-15

    Aptamers have been utilized as biosensors because they can be readily adapted to sensor platforms and signal transduction schemes through both rational design and selection. One highly generalizable scheme for the generation of the so-called aptamer beacons involves denaturing the aptamer with antisense oligonucleotides. For example, rational design methods have been utilized to adapt anti-thrombin aptamers to function as biosensors by hybridizing an antisense oligonucleotide containing a quencher to the aptamer containing a fluorescent label. In the presence of thrombin, the binding equilibrium is shifted, the antisense oligonucleotide dissociates, and the beacon lights up. By changing the affinity of the antisense oligonucleotide for the aptamer beacon, it has proven possible to change the extent of activation of the beacon. More importantly, modulating interactions between the antisense oligonucleotide and the aptamer strongly influences the kinetics of activation. Comparisons across multiple, designed aptamer beacons indicate that there is a strong inverse correlation between the thermodynamics of hybridization and the speed of activation, a finding that should prove to be generally useful in the design of future biosensors. By pre-organizing the thrombin-binding quadruplex within the aptamer the speed of response can be greatly increased. By integrating these various interactions, we were ultimately able to design aptamer beacons that were activated by threefold within 1 min of the addition of thrombin.

  14. Shedding light on health and disease using molecular beacons.

    PubMed

    Tsourkas, Andrew; Bao, Gang

    2003-01-01

    The detection and identification of pathogens is often painstaking due to the low abundance of diseased cells in clinical samples. The genomic sequences of the pathogen can be amplified through methods such as the polymerase chain reaction and nucleic acid sequence-based amplification, but the nucleic acid targets are often lost among other unintended products of amplification. Novel nucleic acid probes known as molecular beacons have been developed allowing for the rapid and specific detection of genetic markers of a disease. Molecular beacons are hairpin-forming oligonucleotides labelled at one end with a quencher and at the other end with a fluorescent reporter dye. In the absence of target, the fluorescence is quenched. In the presence of target, the hairpin structure opens upon beacon/target hybridisation, resulting in the restoration of fluorescence. The ability to transduce target recognition into a fluorescence signal with high signal-to-background ratio, coupled with an improved specificity, has allowed molecular beacons to enjoy a wide range of biological and biomedical applications. Here, we describe the basic features of molecular beacons, review their applications in disease detection and diagnosis and discuss some of the issues and challenges of in vivo studies. The aim of this paper is to foster the development of new molecular beacon-based assays and to stimulate the application of this technology in laboratory and clinical studies of health and disease.

  15. Multiple systems for spatial learning: dead reckoning and beacon homing in rats.

    PubMed

    Shettleworth, Sara J; Sutton, Jennifer E

    2005-04-01

    Rats homed with food in a large lighted arena. Without visual cues, they used dead reckoning. When a beacon indicated the home, rats could also use the beacon. Homing did not differ in 2 groups of rats, 1 provided with the beacon and 1 without it; tests without the beacon gave no evidence that beacon learning overshadowed dead reckoning (Experiment 1). When the beacon was at the home for 1 group and in random locations for another, there was again no evidence of cue competition (Experiment 2). Dead reckoning experience did not block acquisition of beacon homing (Experiment 3). Beacon learning and dead reckoning do not compete for predictive value but acquire information in parallel and are used hierarchically.

  16. Development of Beacon technology. Quarterly report, July-September 1981

    SciTech Connect

    Not Available

    1982-06-01

    The BEACON process involves the catalytic deposition of carbon from a gas stream containing carbon monoxide, and subsequent exposure of this carbon to a gas stream containing hydrogen or steam at elevated temperature and pressure to produce methane. The steam gasification route currently is receiving the most attention. Multiple-cycle tests with K1 and K2 catalysts showed sustained activity and stable performance through thirty of the planned forty cycles. The tests will be completed next quarter. Steaming temperature screening tests on K2-based BEACON carbon supported the conclusion based on earlier testing with K1-based BEACON carbon that steam gasification at two temperature levels has significant advantages over steam gasification at a single temperature in terms of gasification rates and methane yields. Multiple-cycle testing of K2-based BEACON carbon was started in the 4-inch bench-scale fluid bed reactor. Catalyst C77 continued to have problems during multiple-cycle testing - loss of catalytic activity, possibly due to overheating, and poor fluidizability. Further modifications of the C77 catalyst preparation technique were tested. Catalyst C77-K2 showed no change in performance, and results with catalyst C77-K1 were generally disappointing. Laboratory experiments continued with catalyst C78. A variable differential pressure concept which does not require gas/solids separtion is now being considered for the transfer of BEACON solids between carbon deposition and carbon gasification reactors.

  17. Tiny molecular beacons for in vivo mRNA detection.

    PubMed

    Bratu, Diana P; Catrina, Irina E; Marras, Salvatore A E

    2011-01-01

    The molecular beacon technology is an established approach for visualizing native mRNAs in living cells. These probes need to efficiently hybridize to accessible RNA regions in order to spatially and temporally resolve the dynamic steps of the RNA life cycle. A refined method using two computer algorithms, mfold and RNAstructure, is described for choosing shorter, more abundant target regions for molecular beacon binding. The probes are redesigned as small hairpins and are synthesized from 2'-O-methyl RNA/LNA chimeric nucleic acids. These tiny molecular beacons are stable in the cellular environment and have a high affinity for binding to target RNAs. The user-friendly synthesis protocol and ability to couple to a variety of fluorophores make tiny molecular beacons the optimal technology to detect less abundant, highly structured RNAs, as well as small RNAs, such as microRNAs. As an example, tiny chimeric molecular beacons were designed to target regions of oskar mRNA, microinjected into living Drosophila melanogaster oocytes and imaged via spinning disc confocal microscopy.

  18. Optical bidirectional beacon based visible light communications.

    PubMed

    Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon Ho

    2015-10-01

    In an indoor bidirectional visible light communications (VLC), a line-of-sight (LOS) transmission plays a major role in obtaining adequate performance of a VLC system. Signals are often obstructed in the LOS transmission path, causing an effect called optical shadowing. In the absence of LOS, the performance of the VLC system degrades significantly and, in particular, at uplink transmission this degradation becomes severe due to design constraints and limited power at uplink devices. In this paper, a novel concept and design of an optical bidirectional beacon (OBB) is presented as an efficient model to counter the performance degradation in a non-line-of-sight (NLOS) VLC system. OBB is an independent operating bidirectional transceiver unit installed on walls, composed of red, green, and blue (RGB) light emitting diodes (LEDs), photodetectors (PDs) and color filters. OBB improves the coverage area in the form of providing additional or alternate paths for transmission and enhances the performance of the VLC system in terms of bit error rate (BER). To verify the effectiveness of the proposed system, simulations were carried out under optical shadowing conditions at various locations in an indoor environment. The simulation results and analysis show that the implementation of OBB improves the performance of the VLC system significantly, especially when the LOS bidirectional transmission paths are completely or partially obstructed.

  19. Molecular beacons with intrinsically fluorescent nucleotides.

    PubMed

    Martí, Angel A; Jockusch, Steffen; Li, Zengmin; Ju, Jingyue; Turro, Nicholas J

    2006-01-01

    We report the design, synthesis and characterization of a novel molecular beacon (MB-FB) which uses the fluorescent bases (FB) 2-aminopurine (AP) and pyrrolo-dC (P-dC) as fluorophores. Because the quantum yield of these FB depend on hybridization with complementary target, the fluorescent properties of MB-FB were tuned by placing the FB site specifically within the MB such that hybridization with complementary sequence switches from single strand to double strand for AP and vice versa for P-dC. The MB-FB produces a ratiometric fluorescence increase (the fluorescence emission of P-dC over that of AP in the presence and absence of complementary sequence) of 8.5 when excited at 310 nm, the maximum absorption of AP. This ratiometric fluorescence is increased to 14 by further optimizing excitation (325 nm). The fluorescence lifetime is also affected by the addition of target, producing a change in the long-lived component from 6.5 to 8.7 ns (Exc. 310 nm, Em. 450 nm). Thermal denaturation profiles monitored at 450 nm (P-dC emission) show a cooperative denaturation of the MB-FB with a melting temperature of 53 degrees C. The thermal denaturation profile of MB-FB hybridized with its target shows a marked fluorescence reduction at 53 degrees C, consistent with a transition from double stranded helix to random coil DNA.

  20. Molecular beacon lighting up on graphene oxide.

    PubMed

    Huang, Po-Jung Jimmy; Liu, Juewen

    2012-05-01

    A molecular beacon (MB) is comprised of a fluorophore and a quencher linked by a DNA hairpin. MBs have been widely used for homogeneous DNA detection. In addition to molecular quenchers, many nanomaterials such as graphene oxide (GO) also possess excellent quenching efficiency. Most reported fluorescent sensors relied on DNA probes physisorbed by GO, which may suffer from nonspecific probe displacement and false positive signal. In this work, we report the preparation and characterization of a MB using graphene oxide (GO) as quencher, where an amino and FAM (6-carboxyfluorescein) dual labeled DNA was covalently attached to GO via an amide linkage. A major challenge was to remove noncovalently attached probes due to strong DNA adsorption by GO. While DNA desorption was favored at low salt, high pH, high temperature, and by using organic solvents, the cDNA was required to achieve complete desorption of noncovalently linked DNA probes. The DNA adsorption energy was measured using isothermal titration calorimetry, revealing the heterogeneous nature of GO. The covalent probe has a detection limit of 2.2 nM using a sample volume of 0.05 mL. With a 2 mL sample, the detection limit can reach 150 pM. The covalent probe is highly resistant to nonspecific probe displacement and will find applications in serum and cellular samples where high probe stability is demanded.

  1. Chemical imaging sensor and laser beacon.

    PubMed

    Carrieri, Arthur H

    2003-05-20

    Design and functional aspects of PANSPEC, a panoramic-imaging chemical vapor sensor (PANSPEC is an abbreviation for infrared panoramic-viewing spectroradiometer), were advanced and its optical system reoptimized accordingly. The PANSPEC model unites camera and fused solid-state interferometer and photopolarimeter subsystems. The camera is an eye of the open atmosphere that collects, collimates, and images ambient infrared radiance from a panoramic field of view (FOV). The passive interferometer rapidly measures an infrared-absorbing (or infrared-emitting) chemical cloud traversing the FOV by means of molecular vibrational spectroscopy. The active photopolarimeter system provides a laser beam beacon. This beam carries identification (feature spectra measured by the interferometer) and heading (detector pixels disclosing these feature spectra) information on the hazardous cloud through a binary encryption of Mueller matrix elements. Interferometer and photopolarimeter share a common configuration of photoelastic modulation optics. PANSPEC was optimized for minimum aberrations and maximum resolution of image. The optimized design was evaluated for tolerances in the shaping and mounting of the optical system, stray light, and ghost images at the focal plane given a modulation transfer function metric.

  2. Beacons of Hope: New York City's School-Based Community Centers. Program Focus.

    ERIC Educational Resources Information Center

    McGillis, Daniel

    This Program Focus discusses the strategies of the Beacon Community Center Program (the Beacons), the history of its crime prevention programs, and general operations. It focuses on the activities of one particular program, Red Hook in Brooklyn (New York City), before analyzing the Beacons' potential for preventing crime. A core concept of the…

  3. A Place to Grow: Evaluation of the New York City Beacons. Final Report

    ERIC Educational Resources Information Center

    Warren, Constancia; Feist, Michelle; Nevarez, Nancy

    2002-01-01

    This study examined six Beacon centers, which are community centers located in public school buildings that offer a range of activities and services to participants of all ages, before and after school, in the evenings, and on weekends. Individual Beacons are managed by community-based organizations. The study examined how the Beacons provided…

  4. 14 CFR 171.321 - DME and marker beacon performance requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false DME and marker beacon performance... (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the..._regulations/ibr_locations.html. (b) MLS marker beacon equipment must meet the performance...

  5. 33 CFR 149.535 - What are the requirements for rotating beacons on platforms?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... rotating beacons on platforms? 149.535 Section 149.535 Navigation and Navigable Waters COAST GUARD... EQUIPMENT Aids to Navigation Lights on Platforms § 149.535 What are the requirements for rotating beacons on... rotating beacon that distinguishes the deepwater port from other surrounding offshore structures....

  6. 76 FR 17625 - Proposed Information Collection; Comment Request; Emergency Beacon Registrations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-30

    ... Beacon Registrations AGENCY: National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION... ships, aircraft, or individuals in distress if they are equipped with an emergency radio beacon. Persons purchasing a digital distress beacon, operating in the frequency range of 406.000 to 406.100 MHz,...

  7. 14 CFR 171.321 - DME and marker beacon performance requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false DME and marker beacon performance... (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the..._regulations/ibr_locations.html. (b) MLS marker beacon equipment must meet the performance...

  8. 33 CFR 149.535 - What are the requirements for rotating beacons on platforms?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... rotating beacons on platforms? 149.535 Section 149.535 Navigation and Navigable Waters COAST GUARD... EQUIPMENT Aids to Navigation Lights on Platforms § 149.535 What are the requirements for rotating beacons on... rotating beacon that distinguishes the deepwater port from other surrounding offshore structures....

  9. 76 FR 65216 - Beacon Medical Services, LLC, Aurora, CO; Notice of Negative Determination Regarding Application...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... (76 FR 40401). The workers of Beacon Medical Services are engaged in activities related ] to the... Employment and Training Administration Beacon Medical Services, LLC, Aurora, CO; Notice of Negative... apply for Trade Adjustment Assistance (TAA) applicable to workers and former workers of Beacon...

  10. 14 CFR 171.321 - DME and marker beacon performance requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false DME and marker beacon performance... (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the..._regulations/ibr_locations.html. (b) MLS marker beacon equipment must meet the performance...

  11. 33 CFR 149.535 - What are the requirements for rotating beacons on platforms?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... rotating beacons on platforms? 149.535 Section 149.535 Navigation and Navigable Waters COAST GUARD... EQUIPMENT Aids to Navigation Lights on Platforms § 149.535 What are the requirements for rotating beacons on... rotating beacon that distinguishes the deepwater port from other surrounding offshore structures....

  12. 33 CFR 149.580 - What are the requirements for a radar beacon?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false What are the requirements for a radar beacon? 149.580 Section 149.580 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Navigation Miscellaneous § 149.580 What are the requirements for a radar beacon? (a) A radar beacon...

  13. 14 CFR 171.321 - DME and marker beacon performance requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false DME and marker beacon performance... (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the..._regulations/ibr_locations.html. (b) MLS marker beacon equipment must meet the performance...

  14. 33 CFR 149.535 - What are the requirements for rotating beacons on platforms?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... rotating beacons on platforms? 149.535 Section 149.535 Navigation and Navigable Waters COAST GUARD... EQUIPMENT Aids to Navigation Lights on Platforms § 149.535 What are the requirements for rotating beacons on... rotating beacon that distinguishes the deepwater port from other surrounding offshore structures....

  15. 14 CFR 171.321 - DME and marker beacon performance requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false DME and marker beacon performance... (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the..._regulations/ibr_locations.html. (b) MLS marker beacon equipment must meet the performance...

  16. 33 CFR 149.580 - What are the requirements for a radar beacon?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false What are the requirements for a radar beacon? 149.580 Section 149.580 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Navigation Miscellaneous § 149.580 What are the requirements for a radar beacon? (a) A radar beacon...

  17. 33 CFR 149.535 - What are the requirements for rotating beacons on platforms?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... rotating beacons on platforms? 149.535 Section 149.535 Navigation and Navigable Waters COAST GUARD... EQUIPMENT Aids to Navigation Lights on Platforms § 149.535 What are the requirements for rotating beacons on... rotating beacon that distinguishes the deepwater port from other surrounding offshore structures....

  18. 33 CFR 149.580 - What are the requirements for a radar beacon?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false What are the requirements for a radar beacon? 149.580 Section 149.580 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Navigation Miscellaneous § 149.580 What are the requirements for a radar beacon? (a) A radar beacon...

  19. 33 CFR 149.580 - What are the requirements for a radar beacon?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false What are the requirements for a radar beacon? 149.580 Section 149.580 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Navigation Miscellaneous § 149.580 What are the requirements for a radar beacon? (a) A radar beacon...

  20. A Place To Grow: Evaluation of the New York City Beacons. Summary Report.

    ERIC Educational Resources Information Center

    Warren, Constancia; Feist, Michelle; Nevarez, Nancy

    This study examined six Beacon centers, which are community centers located in public school buildings that offer a range of activities and services to participants of all ages, before and after school, in the evenings, and on weekends. Individual Beacons are managed by community-based organizations. The study examined how the Beacons provided…

  1. 33 CFR 149.580 - What are the requirements for a radar beacon?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false What are the requirements for a radar beacon? 149.580 Section 149.580 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Navigation Miscellaneous § 149.580 What are the requirements for a radar beacon? (a) A radar beacon...

  2. A modified molecular beacon combining the properties of TaqMan probe.

    PubMed

    Kong, De-Ming; Gu, Long; Shen, Han-Xi; Mi, Huai-Feng

    2002-04-21

    A modified molecular beacon that possesses a stem-hairpin structure as seen in conventional molecular beacons and can be cleaved during PCR in designed, and it can specifically recognize the presence of the target and was obviously more sensitive than conventional molecular beacons.

  3. PNA HyBeacons for analysis of human mutations related to statin-induced myopathy

    PubMed Central

    Gale, Nittaya; Kocalka, Petr; Mardle, Charlotte

    2011-01-01

    Aminoalkyl and alkyne-tagged PNA HyBeacons have been synthesized, labeled with fluorescein via conventional amide bond or triazole formation (click chemistry) and used to detect single nucleotide polymorphisms (SNPs) implicated in statin-induced myopathy. The PNA HyBeacons gave much better mismatch/mutant discrimination than conventional DNA HyBeacons but smaller fluorescence changes on melting. PMID:22567191

  4. Comparison of BEACON and COMPARE reactor cavity subcompartment analyses

    SciTech Connect

    Burkett, M.W.; Idar, E.S.; Gido, R.G.; Lime, J.F.; Koestel, A.

    1984-04-01

    In this study, a more advanced best-estimate containment code, BEACON-MOD3A, was ued to calculate force and moment loads resulting from a high-energy blowdown for two reactor cavity geometries previously analyzed with the licensing computer code COMPARE-MOD1A. The BEACON force and moment loads were compared with the COMPARE results to determine the safety margins provided by the COMPARE code. The forces and moments calculated by the codes were found to be different, although not in any consistent manner, for the two reactor cavity geometries studied. Therefore, generic summary statements regarding margins cannot be made because of the effects of the detailed physical configuration. However, differences in the BEACON and COMPARE calculated forces and moments can be attributed to differences in the modeling assumptions used in the codes and the analyses.

  5. Molecular beacon real-time PCR detection of swine viruses.

    PubMed

    McKillen, John; Hjertner, Bernt; Millar, Andrena; McNeilly, Francis; Belák, Sándor; Adair, Brian; Allan, Gordon

    2007-03-01

    Rapid and reliable detection of viral pathogens is critical for the management of the diseases threatening the economic competitiveness of the swine farming industry worldwide. Molecular beacon assays are one type of real-time polymerase chain reaction (PCR) technology capable of fast, specific, sensitive, and reliable viral detection. In this paper, the development of molecular beacon assays as novel tools for the rapid detection of Aujeszky's disease virus, African swine fever virus, porcine circovirus type 2 and porcine parvovirus is described. The assays are capable of rapidly detecting 2 x 10(1) copies of target and are linear between 2 x 10(9) and 2 x 10(2) copies. They can detect virus specifically in clinical samples such as whole blood, serum and tissue. In comparison to conventional PCR they are either as sensitive or more sensitive. As such these molecular beacon assays represent a powerful tool for the detection of these viruses in swine.

  6. Near Infrared Imaging of Molecular Beacons in Cancers

    NASA Astrophysics Data System (ADS)

    Chance, Britton

    2001-03-01

    The recent demonstrations of the efficacy of the tumor to background contrast in breast cancer using the tricarbo-cyanine near infrared (NIR) agent with time domain 2-D imaging presages the greater efficacy of site-directed optical contrast agents for early detection of cancers which show contrast (tissue to background) of over 20 fold. Further increases of contrast are obtained with structures that quench the fluorescence until the agent is delivered, recognized, and opened by specific enzymatic activity of the tumor. These are termed ``Molecular Beacons". In order to image the localization of the Beacons, we employ light pen (< 40μ) scanning of the freeze trapped tumor in order to immobilize the tissue, to increase the fluorescence quantum yield and to limit the penetration of the excitation to a thin superficial layer (< 20μ). Precision milling of layers (> 20μ) in LN2 gives the desired 3D high resolution image of the location of the Beacon within in the cancer cell. Since cancer prevention is linked to early detection, the high signal to background obtainable with Molecular Beacons enables the detection of very early subsurface cancers, especially breast and prostate (NIH, UIP). Thus the fluorescent Beacon excites and emits in the NIR window and signals from several cm deep in breast are detected by diffusive wave optical tomography (DWOT). Detection of objects (< 1 mm) is achieved by phased array optical system using 0^O, 180^O 50 MHz modulation of pairs of laser diodes (780 nm) and fluorescence detection (> 800 nm) affording 0.2 mm object detection of even low Beacon concentrations. One, two, and 3-D localization is made possible by one, two, and three orthogonal phase array null planes.

  7. Omnidirectional beacon-localization using a catadioptric system.

    PubMed

    Shen, Thomas C; Drost, Robert J; Sadler, Brian M; Rzasa, John R; Davis, Christopher C

    2016-04-01

    We present a catadioptric beacon localization system that can provide mobile network nodes with omnidirectional situational awareness of neighboring nodes. In this system, a receiver composed of a hyperboloidal mirror and camera is used to estimate the azimuth, elevation, and range of an LED beacon. We provide a general framework for understanding the propagation of error in the angle-of-arrival estimation and then present an experimental realization of such a system. The situational awareness provided by the proposed system can enable the alignment of communication nodes in an optical wireless network, which may be particularly useful in addressing RF-denied environments. PMID:27136988

  8. Frequency Estimator Performance for a Software-Based Beacon Receiver

    NASA Technical Reports Server (NTRS)

    Zemba, Michael J.; Morse, Jacquelynne Rose; Nessel, James A.; Miranda, Felix

    2014-01-01

    As propagation terminals have evolved, their design has trended more toward a software-based approach that facilitates convenient adjustment and customization of the receiver algorithms. One potential improvement is the implementation of a frequency estimation algorithm, through which the primary frequency component of the received signal can be estimated with a much greater resolution than with a simple peak search of the FFT spectrum. To select an estimator for usage in a QV-band beacon receiver, analysis of six frequency estimators was conducted to characterize their effectiveness as they relate to beacon receiver design.

  9. Omnidirectional beacon-localization using a catadioptric system.

    PubMed

    Shen, Thomas C; Drost, Robert J; Sadler, Brian M; Rzasa, John R; Davis, Christopher C

    2016-04-01

    We present a catadioptric beacon localization system that can provide mobile network nodes with omnidirectional situational awareness of neighboring nodes. In this system, a receiver composed of a hyperboloidal mirror and camera is used to estimate the azimuth, elevation, and range of an LED beacon. We provide a general framework for understanding the propagation of error in the angle-of-arrival estimation and then present an experimental realization of such a system. The situational awareness provided by the proposed system can enable the alignment of communication nodes in an optical wireless network, which may be particularly useful in addressing RF-denied environments.

  10. Frequency Estimator Performance for a Software-Based Beacon Receiver

    NASA Technical Reports Server (NTRS)

    Zemba, Michael J.; Morse, Jacquelynne R.; Nessel, James A.

    2014-01-01

    As propagation terminals have evolved, their design has trended more toward a software-based approach that facilitates convenient adjustment and customization of the receiver algorithms. One potential improvement is the implementation of a frequency estimation algorithm, through which the primary frequency component of the received signal can be estimated with a much greater resolution than with a simple peak search of the FFT spectrum. To select an estimator for usage in a Q/V-band beacon receiver, analysis of six frequency estimators was conducted to characterize their effectiveness as they relate to beacon receiver design.

  11. Earth laser beacon sensor for earth-oriented geosynchronous satellites.

    PubMed

    Sepp, G

    1975-07-01

    Geosynchronous satellites are often required to maintain accurately their orientation with respect to a selected point at the earth surface. Precise attitude determination of these satellites may be achieved using a laser beacon from ground to the satellite as a directional reference. Four simple implementations of this principle are analyzed, and the influence of the cloudy atmosphere on the laser beacon and, therefore, on the accuracy of the method is discussed. All-weather operation is not possible; for normal cloudiness conditions, however, two analyzed systems (pulsed Nd:YAG laser with photomultiplier and CO(2) laser with cryogenic detector) appear to be feasible.

  12. Journey to the Beacon Award: the Georgetown University Hospital perspective.

    PubMed

    Jaworski Miller, Lisa; Corbett, Gina; Herold, Mary; Tavares, Doris; Kirchner, Lisa; Heath, Janie

    2005-06-01

    The medical intensive care unit (MICU) at Georgetown University Hospital in Washington, D.C., was among the first four hospitals to be awarded the Beacon Award from the American Association of Critical- Care Nurses. The Beacon Award is given to those units that prove, through a 42-question application, how they excel and serve as a guiding light to other intensive care units. The MICU's "journey" to the award prompted an introspective look into the unit, its policies, and its methods of providing the highest quality patient care, in an environment that is supportive to the nursing staff.

  13. Overshadowing of geometric cues by a beacon in a spatial navigation task.

    PubMed

    Redhead, Edward S; Hamilton, Derek A; Parker, Matthew O; Chan, Wai; Allison, Craig

    2013-06-01

    In three experiments, we examined whether overshadowing of geometric cues by a discrete landmark (beacon) is due to the relative saliences of the cues. Using a virtual water maze task, human participants were required to locate a platform marked by a beacon in a distinctively shaped pool. In Experiment 1, the beacon overshadowed geometric cues in a trapezium, but not in an isosceles triangle. The longer escape latencies during acquisition in the trapezium control group with no beacon suggest that the geometric cues in the trapezium were less salient than those in the triangle. In Experiment 2, we evaluated whether generalization decrement, caused by the removal of the beacon at test, could account for overshadowing. An additional beacon was placed in an alternative corner. For the control groups, the beacons were identical; for the overshadow groups, they were visually unique. Overshadowing was again found in the trapezium. In Experiment 3, we tested whether the absence of overshadowing in the triangle was due to the geometric cues being more salient than the beacon. Following training, the beacon was relocated to a different corner. Participants approached the beacon rather than the trained platform corner, suggesting that the beacon was more salient. These results suggest that associative processes do not fully explain cue competition in the spatial domain.

  14. Structure-function relationships of shared-stem and conventional molecular beacons.

    PubMed

    Tsourkas, Andrew; Behlke, Mark A; Bao, Gang

    2002-10-01

    Molecular beacons are oligonucleotide probes capable of forming a stem-loop hairpin structure with a reporter dye at one end and a quencher at the other end. Conventional molecular beacons are designed with a target-binding domain flanked by two complementary short arm sequences that are independent of the target sequence. Here we report the design of shared-stem molecular beacons with one arm participating in both stem formation when the beacon is closed and target hybridization when it is open. We performed a systematic study to compare the behavior of conventional and shared-stem molecular beacons by conducting thermodynamic and kinetic analyses. Shared-stem molecular beacons form more stable duplexes with target molecules than conventional molecular beacons; however, conventional molecular beacons may discriminate between targets with a higher specificity. For both conventional and shared-stem molecular beacons, increasing stem length enhanced the ability to differentiate between wild-type and mutant targets over a wider range of temperatures. Interestingly, probe-target hybridization kinetics were similar for both classes of molecular beacons and were influenced primarily by the length and sequence of the stem. These findings should enable better design of molecular beacons for various applications.

  15. Target discrimination by surface-immobilized molecular beacons designed to detect Francisella tularensis.

    PubMed

    Ramachandran, Akhilesh; Flinchbaugh, James; Ayoubi, Patricia; Olah, Glenn A; Malayer, Jerry R

    2004-02-15

    A molecular beacon (MB) array was designed based on unique regions of the 16S rRNA of the bacterium Francisella tularensis. Nucleic acid molecular beacons undergo a spontaneous fluorogenic conformational change when they hybridize to specific complementary targets. The array was printed on aldehyde glass or hydrogel slides and evaluated for functioning in presence of complementary oligonucleotide sequences, single-nucleotide mismatch sequences and multiple nucleotide mismatch sequences. Discriminating true target from mismatched targets was found to be dependent on type, number, and location of mismatches within the beacon (i.e. located in the stem or loop regions). Optimal conditions for molecular beacon deposition, and target hybridization were determined for oligonucleotide target mismatch discrimination. The beacon array was stable upon recharging by exposure to an alkaline solution, and repeatedly used. In addition, performance of the beacon array biosensor was compared with molecular beacons in homogeneous solution.

  16. Evolution of stratospheric chemistry in the Saturn storm beacon region

    NASA Astrophysics Data System (ADS)

    Moses, Julianne I.; Armstrong, Eleanor S.; Fletcher, Leigh N.; Friedson, A. James; Irwin, Patrick G. J.; Sinclair, James A.; Hesman, Brigette E.

    2015-11-01

    The giant northern-hemisphere storm that erupted on Saturn in December 2010 triggered significant changes in stratospheric temperatures and species abundances that persisted for more than a year after the original outburst. The stratospheric regions affected by the storm have been nicknamed "beacons" due to their prominent infrared-emission signatures (Fletcher, L.N. et al. [2011]. Science 332, 1413). The two beacon regions that were present initially merged in April 2011 to form a single, large, anticyclonic vortex (Fletcher, L.N. et al. [2012]. Icarus 221, 560). We model the expected photochemical evolution of the stratospheric constituents in the beacons from the initial storm onset through the merger and on out to March 2012. The results are compared with longitudinally resolved Cassini/CIRS spectra from May 2011. If we ignore potential changes due to vertical winds within the beacon, we find that C2H2, C2H6, and C3H8 remain unaffected by the increased stratospheric temperatures in the beacon, the abundance of the shorter-lived CH3C2H decreases, and the abundance of C2H4 increases significantly due to the elevated temperatures, the latter most notably in a secondary mixing-ratio peak located near mbar pressures. The C4H2 abundance in the model decreases by a factor of a few in the 0.01-10 mbar region but has a significant increase in the 10-30 mbar region due to evaporation of the previously condensed phase. The column abundances of C6H6 and H2O above ∼30 mbar also increase due to aerosol evaporation. Model-data comparisons show that models that consider temperature changes alone underpredict the abundance of C2Hx species by a factor of 2-7 in the beacon core in May 2011, suggesting that other processes not considered by the models, such as downwelling winds in the vortex, are affecting the species profiles. Additional calculations indicate that downwelling winds of order - 10 cm s-1 near ∼0.1 mbar need to be included in the photochemical models in order to

  17. Differential expression and function of beacon in the rat adrenal cortex and medulla.

    PubMed

    Rucinski, Marcin; Andreis, Paola G; Ziolkowska, Agnieszka; Nussdorfer, Gastone G; Malendowicz, Ludwik K

    2005-07-01

    Beacon gene is overexpressed in obese rats, and beacon was found to stimulate food intake. Evidence has been recently provided that beacon is also expressed in the endocrine glands of normal rats, including adrenal cortex, of which it appears to regulate secretory activity. To further characterize the role of beacon in the rat adrenals, we investigated the level of beacon expression in the adrenal zona glomerulosa (ZG), zona fasciculata-reticularis (ZF/R) and medulla (AM), and the in vitro secretory responses to beacon[47-73] (hereinafter, beacon) of adrenocortical and adrenomedullary tissues. Real-time polymerase chain reaction revealed similar high levels of beacon mRNA in the ZG and ZF/R, and significantly lower (-80%) levels in AM. Immunocytochemistry showed that the distribution of beacon protein followed that of beacon mRNA. Quantitative high pressure liquid chromatography demonstrated that beacon (5x10(-7) M) reduced by about 56% the in vitro total steroid-hormone production from ZG and ZF/R tissues, without affecting catecholamine secretion from AM specimens. The beacon-induced lowering in the secretory activity of adrenal cortex depended on similar reductions (from 50-64%) in the production of the main adrenocortical hormones (pregnenolone, progesterone, 11-deoxycorticosterone, corticosterone, 18-hydroxy-corticosterone and aldosterone), thereby suggesting an inhibitory action of beacon in the early step of steroidogenesis (i.e. the conversion of cholesterol to pregnenolone). The hypothesis is advanced that beacon is to be considered an autocrine-paracrine negative regulator of mineralo- and glucocorticoid synthesis in the rat adrenal gland.

  18. The morpholino molecular beacon for specific RNA visualization in vivo.

    PubMed

    Chen, Jianbin; Wu, Jikui; Hong, Yunhan

    2016-02-21

    A non-invasive fluorescent probe, morpholino molecular beacon (MO-MB), was designed for RNA visualization in vivo. Featuring negligible toxicity, stability, and high target specificity in living embryos, MO-MB is superior to conventional probes and has the potential for specific RNA visualization in basic biological and clinical research.

  19. A Climate Created: Community Building in the Beacon College Project.

    ERIC Educational Resources Information Center

    Barnett, Lynn

    From 1989 to 1995, the American Association of Community Colleges implemented the Beacon College Project to help community colleges develop creative and practical community-building strategies through collaborative initiatives. This report reviews the philosophy behind the project and describes goals and outcomes for the 26 institutions selected…

  20. Standing on lightpost and day beacon, haer architect Christopher Marston ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Standing on lightpost and day beacon, haer architect Christopher Marston points to stone retaining wall at site of old monongahela navigation company lock & dam no. 7. - Monongahela Navigation Company Lock & Dam No. 7, River Mile No. 82.5, Greensboro, Greene County, PA

  1. Development of BEACON technology. Quarterly report, January-March 1981

    SciTech Connect

    Not Available

    1981-07-01

    The BEACON process involves the catalytic deposition of carbon from a gas stream containing carbon monoxide, and subsequent exposure of this carbon to a gas stream containing hydrogen or steam at elevated temperature and pressure to produce methane. The steam gasification route currently is receiving the most attention. Testing of steam gasification of BEACON carbon over a range of temperatures and pressures in bench-scale equipment has led to the conclusion that steam gasification at two temperature levels has significant advantages over steam gasification at a single temperature in terms of gasification rates and methane yields. Laboratory experiments with catalyst C77 investigated the effects of process variables, catalyst composition modifications, and feed gas compositions on carbon deposition and gasification rates, carbon monoxide and steam utilization, and cycle efficiency. Laboratory experiments to find materials that will promote the carbon deposition rate of BEACON catalysts were highly successful. Promoted catalysts showed significantly higher carbon deposition rates and carbon monoxide utilization than unpromoted catalysts. Multiple-cycle performance of BEACON catalysts also is reported.

  2. Radiometer calibration procedure and beacon attenuation estimation reference level

    NASA Technical Reports Server (NTRS)

    Crane, Robert K.

    1994-01-01

    The primary objectives are to compare radiometer attenuation with beacon attenuation and to compare sky temperature estimates with calculations using simultaneous meteorological data. Secondary objectives are: (1) noise diode and reference load measurements and (2) to adjust for outside temperature and component temperature changes.

  3. Design of a hybrid receiver for the OLYMPUS spacecraft beacons

    NASA Technical Reports Server (NTRS)

    Sweeney, D. G.; Mckeeman, J. C.

    1990-01-01

    The theory and design of a hybrid analogue/digital receiver which acquires and monitors the OLYMPUS satellite beacons is presented. The analogue portion of this receiver uses a frequency locked loop for signal tracking. A digital sampling detector operating at IF is used to obtain the I and Q outputs.

  4. Promoting Health in Hospitals: The Role of Beacon

    ERIC Educational Resources Information Center

    Whitelaw, Sandy; Watson, Jonathan; Hennessy, Sue

    2004-01-01

    "Best practice" is currently being used to enable modernisation within the National Health Service (NHS) in the United Kingdom. One element of this is the Beacon programme where examples of hospitals that exemplify local "best practice" are supported to develop and disseminate learning across the wider NHS. The aims of this research were to map…

  5. COSPAS/SARSAT 406-MHz emergency beacon digital controller

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.

    1988-01-01

    The digital control portion of a low-cost 406-MHz COSPAS/SARSAT emergency beacon has been designed and breadboarded at the NASA Lewis Research Center. This report discusses the requirements and design tradeoffs of the digital controller and describes the hardware and software design, which is available only to United States citizens and companies.

  6. Epilithic lichens in the Beacon sandstone formation, Victoria Land, Antarctica

    NASA Technical Reports Server (NTRS)

    Hale, M. E.; Friedmann, E. I. (Principal Investigator)

    1987-01-01

    The epilithic lichen flora on the Beacon sandstone formation in Victoria Land consists of seven species: Acarospora gwynnii Dodge & Rudolph, Buellia grisea Dodge & Baker, B. pallida Dodge & Baker, Carbonea capsulata (Dodge & Baker) Hale comb. nov., Lecanora fuscobrunnea Dodge & Baker, Lecidea cancriformis Dodge & Baker, and L. siplei Dodge & Baker. The typification of the species is given along with descriptions and distribution in Antarctica.

  7. A polycation-chaperoned in-stem molecular beacon system.

    PubMed

    Asanuma, Hiroyuki; Osawa, Takuya; Kashida, Hiromu; Fujii, Taiga; Liang, Xingguo; Niwa, Kosuke; Yoshida, Yasuko; Shimada, Naohiko; Maruyama, Atsushi

    2012-02-01

    In the presence of poly(L-lysine)-graft-dextran, an in-stem molecular beacon involving three perylene-anthraquinone pairs in the stem region had a signal/background ratio of as high as 570. Response speed was also remarkable; equilibrium was attained within 5 minutes after addition of substrate DNA at 20 °C.

  8. DNAzyme catalytic beacon sensors that resist temperature-dependent variations.

    PubMed

    Nagraj, Nandini; Liu, Juewen; Sterling, Stephanie; Wu, Jenny; Lu, Yi

    2009-07-21

    The temperature-dependent variability of a Pb2+-specific 8-17E DNAzyme catalytic beacon sensor has been addressed through the introduction of mismatches in the DNAzyme, and the resulting sensors resist temperature-dependent variations from 4 to 30 degrees C.

  9. The Methodist Hospital CCU: a Beacon unit of excellence.

    PubMed

    Lewis, Tricia; Abanobi, Beatrice; Alleman, Paula; Ballinas, Eva; Botbyl, Brenda; Bries, Girlie; Clark, Liz; Clarkson, Terri; Cooper, Bridgette; Cooper, Jason; Cox, Shelly; Cude, Rebecca; Davis, Juanita; Delosreyes, Arlene; Durst, Kimberly; East, Ana; Edwards, Erving; Ellison, Rose; Eparwa, Perlita; Forjuoh, Harriet; Foster, Donald; Foytik, Lisa; Gordon, Maria; Grace, Jean; Green, Lisa; Harrison, Cassandra; Herrera, Rubin; Horn, Mary; Hunsinger, Cheryce; Issac, Annamma; Jackson, Valerie; Johnson, Athie; Kitayama, Susanna; Karaan, Juliet; Kezmarski, Mary; Kleinrock, Richard; Latson, Maria; Lee, Valerie; Long, Robin; Macapagal, Fred; Magsino, Diana; Manojkumar, Saleena; Martin, Denise; Matura, Lea Ann; McCarthy, Cynthia; McClellan, Emma; McDaniel, Christy; Mengo, Pam; Meurer, Judy; Muttathottil, Liz; Osayande, Esther; Osei-Frimpong, Diana; Phillips, Betty; Pittman, James; Pratt, Craig; Putney, David; Refuerzo, Laarni; Rendon, Lavinia; Richter, Russ; Simms, Sylvia; Sitoy, Diana; Small-Nelson, Judith; Sosa, Tomas; Stuckey, Denise; Tacquard, Natalie; Talbott, Sarah; Talladen, Aleine; Taylor, Shani; Thomas, Lini; Thompson, Pam; Walters, Gordon; West, Rachel

    2005-06-01

    This article features the Coronary Care Unit of The Methodist Hospital of Houston, Texas. This unit was one of the first Beacon Critical Care Units recognized by the American Association of Critical Care Nurses. This article focuses on how to achieve this award. The Coronary Care Unit nursing infrastructure is described, and specific unit examples are included.

  10. Molecular beacons for DNA biosensors with micrometer to submicrometer dimensions.

    PubMed

    Liu, X; Farmerie, W; Schuster, S; Tan, W

    2000-07-15

    Ultrasensitive molecular beacon (MB) DNA biosensors, with micrometer to submicrometer sizes, have been developed for DNA/RNA analysis. The fluorescence-based biosensors have been applied in DNA/ RNA detection without the need for a dye-labeled target molecule or an intercalation reagent in the testing solution. Molecular beacons are hairpin-shaped oligonucleotides that report the presence of specific nucleic acids. We have designed a surface-immobilizable biotinylated ssDNA molecular beacon for DNA hybridization at a liquid-solid interface. The MBs have been immobilized onto ultrasmall optical fiber probes through avidin-biotin binding. The MB DNA biosensor has been used directly to detect, in real time, its target DNA molecules without the need for a competitive assay. The biosensor is stable and reproducible. The MB DNA biosensor has selectivity with single base-pair mismatch identification capability. The concentration detection limits and mass detection limits are 0.3 nM and 15 amol for a 105-microm biosensor, and 10 nM and 0.27 amol for a submicrometer biosensor, respectively. We have also prepared molecular beacon DNA biosensor arrays for simultaneous analysis of multiple DNA sequences in the same solution. The newly developed DNA biosensors have been used for the precise quantification of a specific rat gamma-actin mRNA sequence amplified by the polymerase chain reaction.

  11. Intermolecular G-quadruplex-based universal quencher free molecular beacon.

    PubMed

    Zhou, Hui; Xie, Su-Jin; Li, Ji-Shan; Wu, Zai-Sheng; Shen, Guo-Li

    2012-11-11

    A simple and universal quencher-free molecular beacon (MB) with low background fluorescence is developed based on an intermolecular G-quadruplex signaling probe. Unlike previous fluorescent MB strategies, it can function without any fluorophore and quencher modifications on its hairpin sequence.

  12. Epilithic lichens in the Beacon sandstone formation, Victoria Land, Antarctica.

    PubMed

    Hale, M E

    1987-01-01

    The epilithic lichen flora on the Beacon sandstone formation in Victoria Land consists of seven species: Acarospora gwynnii Dodge & Rudolph, Buellia grisea Dodge & Baker, B. pallida Dodge & Baker, Carbonea capsulata (Dodge & Baker) Hale comb. nov., Lecanora fuscobrunnea Dodge & Baker, Lecidea cancriformis Dodge & Baker, and L. siplei Dodge & Baker. The typification of the species is given along with descriptions and distribution in Antarctica.

  13. Molecular beacons: a new approach to plant virus detection.

    PubMed

    Eun, A J; Wong, S M

    2000-03-01

    ABSTRACT Molecular beacons are single-stranded nucleic acid molecules with a stem-loop conformation. The stem portion consists of complementary sequences at the 5' and 3' terminals of the molecule, while the loop portion consists of probe sequences that are complementary to the target sequences of choice. A fluorescent moiety is attached to one end, while a quenching moiety is attached to the opposite end. Reverse transcription-polymerase chain reactions are carried out with primers that amplify specific genome sequences of interest, yielding targets complementary to their respective molecular beacons for subsequent detection. Here, we have designed four molecular beacons specific to the RNA-dependent RNA polymerase and coat protein genes of two orchid viruses, namely Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV). This technology is successfully applied to detect as little as 0.5 ng of viral RNA of both orchid viruses simultaneously in 100 mg of coinfected Oncidium orchid leaves. This rapid and specific technique is applicable to the orchid industry, which routinely carries out virus indexing and screening for virus-resistant cultivars. We belief that use of this molecular beacon approach can be extended to the detection of multiple plant viruses in various crops.

  14. The morpholino molecular beacon for specific RNA visualization in vivo.

    PubMed

    Chen, Jianbin; Wu, Jikui; Hong, Yunhan

    2016-02-21

    A non-invasive fluorescent probe, morpholino molecular beacon (MO-MB), was designed for RNA visualization in vivo. Featuring negligible toxicity, stability, and high target specificity in living embryos, MO-MB is superior to conventional probes and has the potential for specific RNA visualization in basic biological and clinical research. PMID:26810703

  15. Reflecting on Pedagogy: Outcomes from a Beacon School Network

    ERIC Educational Resources Information Center

    Bullock, Kate; Muschamp, Yolande

    2004-01-01

    This article arises from an initiative set up by four Beacon Schools to enhance the professional development of teachers and hence raise pupil attainment in all schools in the local education authority. The initiative provided opportunities for teachers to work in cross-institutional interest groups, with the aim of sharing good practice and…

  16. Smartphone-Based Indoor Localization with Bluetooth Low Energy Beacons.

    PubMed

    Zhuang, Yuan; Yang, Jun; Li, You; Qi, Longning; El-Sheimy, Naser

    2016-01-01

    Indoor wireless localization using Bluetooth Low Energy (BLE) beacons has attracted considerable attention after the release of the BLE protocol. In this paper, we propose an algorithm that uses the combination of channel-separate polynomial regression model (PRM), channel-separate fingerprinting (FP), outlier detection and extended Kalman filtering (EKF) for smartphone-based indoor localization with BLE beacons. The proposed algorithm uses FP and PRM to estimate the target's location and the distances between the target and BLE beacons respectively. We compare the performance of distance estimation that uses separate PRM for three advertisement channels (i.e., the separate strategy) with that use an aggregate PRM generated through the combination of information from all channels (i.e., the aggregate strategy). The performance of FP-based location estimation results of the separate strategy and the aggregate strategy are also compared. It was found that the separate strategy can provide higher accuracy; thus, it is preferred to adopt PRM and FP for each BLE advertisement channel separately. Furthermore, to enhance the robustness of the algorithm, a two-level outlier detection mechanism is designed. Distance and location estimates obtained from PRM and FP are passed to the first outlier detection to generate improved distance estimates for the EKF. After the EKF process, the second outlier detection algorithm based on statistical testing is further performed to remove the outliers. The proposed algorithm was evaluated by various field experiments. Results show that the proposed algorithm achieved the accuracy of <2.56 m at 90% of the time with dense deployment of BLE beacons (1 beacon per 9 m), which performs 35.82% better than <3.99 m from the Propagation Model (PM) + EKF algorithm and 15.77% more accurate than <3.04 m from the FP + EKF algorithm. With sparse deployment (1 beacon per 18 m), the proposed algorithm achieves the accuracies of <3.88 m at 90% of the

  17. Smartphone-Based Indoor Localization with Bluetooth Low Energy Beacons.

    PubMed

    Zhuang, Yuan; Yang, Jun; Li, You; Qi, Longning; El-Sheimy, Naser

    2016-04-26

    Indoor wireless localization using Bluetooth Low Energy (BLE) beacons has attracted considerable attention after the release of the BLE protocol. In this paper, we propose an algorithm that uses the combination of channel-separate polynomial regression model (PRM), channel-separate fingerprinting (FP), outlier detection and extended Kalman filtering (EKF) for smartphone-based indoor localization with BLE beacons. The proposed algorithm uses FP and PRM to estimate the target's location and the distances between the target and BLE beacons respectively. We compare the performance of distance estimation that uses separate PRM for three advertisement channels (i.e., the separate strategy) with that use an aggregate PRM generated through the combination of information from all channels (i.e., the aggregate strategy). The performance of FP-based location estimation results of the separate strategy and the aggregate strategy are also compared. It was found that the separate strategy can provide higher accuracy; thus, it is preferred to adopt PRM and FP for each BLE advertisement channel separately. Furthermore, to enhance the robustness of the algorithm, a two-level outlier detection mechanism is designed. Distance and location estimates obtained from PRM and FP are passed to the first outlier detection to generate improved distance estimates for the EKF. After the EKF process, the second outlier detection algorithm based on statistical testing is further performed to remove the outliers. The proposed algorithm was evaluated by various field experiments. Results show that the proposed algorithm achieved the accuracy of <2.56 m at 90% of the time with dense deployment of BLE beacons (1 beacon per 9 m), which performs 35.82% better than <3.99 m from the Propagation Model (PM) + EKF algorithm and 15.77% more accurate than <3.04 m from the FP + EKF algorithm. With sparse deployment (1 beacon per 18 m), the proposed algorithm achieves the accuracies of <3.88 m at 90% of the

  18. Smartphone-Based Indoor Localization with Bluetooth Low Energy Beacons

    PubMed Central

    Zhuang, Yuan; Yang, Jun; Li, You; Qi, Longning; El-Sheimy, Naser

    2016-01-01

    Indoor wireless localization using Bluetooth Low Energy (BLE) beacons has attracted considerable attention after the release of the BLE protocol. In this paper, we propose an algorithm that uses the combination of channel-separate polynomial regression model (PRM), channel-separate fingerprinting (FP), outlier detection and extended Kalman filtering (EKF) for smartphone-based indoor localization with BLE beacons. The proposed algorithm uses FP and PRM to estimate the target’s location and the distances between the target and BLE beacons respectively. We compare the performance of distance estimation that uses separate PRM for three advertisement channels (i.e., the separate strategy) with that use an aggregate PRM generated through the combination of information from all channels (i.e., the aggregate strategy). The performance of FP-based location estimation results of the separate strategy and the aggregate strategy are also compared. It was found that the separate strategy can provide higher accuracy; thus, it is preferred to adopt PRM and FP for each BLE advertisement channel separately. Furthermore, to enhance the robustness of the algorithm, a two-level outlier detection mechanism is designed. Distance and location estimates obtained from PRM and FP are passed to the first outlier detection to generate improved distance estimates for the EKF. After the EKF process, the second outlier detection algorithm based on statistical testing is further performed to remove the outliers. The proposed algorithm was evaluated by various field experiments. Results show that the proposed algorithm achieved the accuracy of <2.56 m at 90% of the time with dense deployment of BLE beacons (1 beacon per 9 m), which performs 35.82% better than <3.99 m from the Propagation Model (PM) + EKF algorithm and 15.77% more accurate than <3.04 m from the FP + EKF algorithm. With sparse deployment (1 beacon per 18 m), the proposed algorithm achieves the accuracies of <3.88 m at 90% of the

  19. Development of BEACON technology. Quarterly report, October-December 1982

    SciTech Connect

    Not Available

    1983-04-01

    The BEACON process involves the catalytic deposition of a highly reactive form of carbon from a gas stream which contains carbon monoxide. The carbon-depleted gas is combusted with air to produce power, and the carbon is reacted with steam to produce methane or hydrogen. During the quarter both SOHIO and TRW worked on catalysts which would suppress methane formation during steaming thus increasing the amount of hydrogen formed. At SOHIO a C77-K2 catalyst promoted with a Class II compound showed promise in laboratory tests for suppressing methane. At TRW a K-1 unsupported catalyst promoted with 10% of Additive F maintained methane suppression over 30 cycles in laboratory scale tests. Shakedown of the Tandem Reactor Apparatus was completed and testing was initiated under quasi-continuous transfer of solids between reactors. Nine short term tests were performed with K-1 based BEACON solids. The data from these tests indicate that the Tandem Reactor concept is valid and BEACON solids can be transferred efficiently in the fluidized state between the deposition and gasification reactors. A preliminary analysis of the potential of a BEACON combined cycle/hydrogen system with a hydrogen fuel cell has been performed. The BEACON process can be used to coproduce hydrogen and electric power, and the efficiency of the overall system is quite high when the electricity is produced by a combined cycle power system. If fuel cells are used to convert the hydrogen to electricity then a system for making only electricity results, and such a system gives an overall efficiency of 54%. 7 figures, 14 tables.

  20. Hybridization of 2'-O-methyl and 2'-deoxy molecular beacons to RNA and DNA targets.

    PubMed

    Tsourkas, Andrew; Behlke, Mark A; Bao, Gang

    2002-12-01

    Molecular beacons are stem-loop hairpin oligonucleotide probes labeled with a fluorescent dye at one end and a fluorescence quencher at the other end; they can differentiate between bound and unbound probes in homogeneous hybridization assays with a high signal-to-background ratio and enhanced specificity compared with linear oligonucleotide probes. However, in performing cellular imaging and quantification of gene expression, degradation of unmodified molecular beacons by endogenous nucleases can significantly limit the detection sensitivity, and results in fluorescence signals unrelated to probe/target hybridization. To substantially reduce nuclease degradation of molecular beacons, it is possible to protect the probe by substituting 2'-O-methyl RNA for DNA. Here we report the analysis of the thermodynamic and kinetic properties of 2'-O-methyl and 2'-deoxy molecular beacons in the presence of RNA and DNA targets. We found that in terms of molecular beacon/target duplex stability, 2'-O-methyl/RNA > 2'-deoxy/RNA > 2'-deoxy/DNA > 2'-O-methyl/DNA. The improved stability of the 2'-O-methyl/RNA duplex was accompanied by a slightly reduced specificity compared with the duplex of 2'-deoxy molecular beacons and RNA targets. However, the 2'-O-methyl molecular beacons hybridized to RNA more quickly than 2'-deoxy molecular beacons. For the pairs tested, the 2'-deoxy-beacon/DNA-target duplex showed the fastest hybridization kinetics. These findings have significant implications for the design and application of molecular beacons.

  1. Hybridization of 2'-O-methyl and 2'-deoxy molecular beacons to RNA and DNA targets.

    PubMed

    Tsourkas, Andrew; Behlke, Mark A; Bao, Gang

    2003-03-15

    Molecular beacons are stem-loop hairpin oligonucleotide probes labeled with a fluorescent dye at one end and a fluorescence quencher at the other end; they can differentiate between bound and unbound probes in homogeneous hybridization assays with a high signal-to-background ratio and enhanced specificity compared with linear oligonucleotide probes. However, in performing cellular imaging and quantification of gene expression, degradation of unmodified molecular beacons by endogenous nucleases can significantly limit the detection sensitivity, and results in fluorescence signals unrelated to probe/target hybridization. To substantially reduce nuclease degradation of molecular beacons, it is possible to protect the probe by substituting 2'-O-methyl RNA for DNA. Here we report the analysis of the thermodynamic and kinetic properties of 2'-O-methyl and 2'-deoxy molecular beacons in the presence of RNA and DNA targets. We found that in terms of molecular beacon/target duplex stability, 2'-O-methyl/RNA > 2'-deoxy/RNA > 2'-deoxy/DNA > 2'-O-methyl/DNA. The improved stability of the 2'-O-methyl/RNA duplex was accompanied by a slightly reduced specificity compared with the duplex of 2'-deoxy molecular beacons and RNA targets. However, the 2'-O-methyl molecular beacons hybridized to RNA more quickly than 2'-deoxy molecular beacons. For the pairs tested, the 2'-deoxy-beacon/DNA-target duplex showed the fastest hybridization kinetics. These findings have significant implications for the design and application of molecular beacons.

  2. Reliability analysis of a multiple-laser-diode beacon for intersatellite links

    NASA Astrophysics Data System (ADS)

    Mauroschat, Andreas

    1991-06-01

    Monte Carlo simulations are used to investigate and evaluate different design options for the SILEX acquisition beacon. A minimum specification for the quality of the optical coupling between the laser diodes and the beacon output for which the beacon meets its power specification with the required reliability is established. An improved reliability is demonstrated for beacon designs with an optimized thermal design including the control of the thermal wall temperature and the conductive coupling between the beacon emission unit and the terminal radiator. Such an optimized thermal design also offers the possibility of mass savings of the optical terminal, since only a very light thermal wall is needed for the beacon. The total power control of the laser diodes is demonstrated to be the best mode of operation.

  3. The New York City Beacons: rebuilding communities of support in urban neighborhoods.

    PubMed

    Kleinbard, Peter

    2005-01-01

    Established in 1991 in New York City and now operating in at least seven other cities, Beacons are designed to rebuild communities of support for children and youth in urban neighborhoods. The Beacon framework is based on research findings and practitioner experience indicating that programs taking a youth development approach are more effective than those focused on "fixing" specific youth problems. Successful Beacon programs provide positive ways to meet young people's need for safety, a sense of belonging, and mastery; they also provide opportunities for decision making and contributing to others. There are currently eighty Beacons in New York City, serving about 140,000 youth and adults annually. Beacons have been replicated in several parts of the country, including Denver, Minneapolis, Oakland, Palm Beach County, Philadelphia, San Francisco, and Savannah. The Youth Development Institute of the Fund for the City of New York provides technical assistance and training to Beacons in New York City and in all seven replication sites.

  4. Interaction between piloting and beacon homing by rats in a swimming pool.

    PubMed

    Redhead, E S; Roberts, A; Good, M; Pearce, J M

    1997-07-01

    In three experiments, rats in a swimming pool were trained to find a submerged platform with a beacon attached to it. For some rats this beacon unambiguously identified the location of the platform; for others the beacon was made ambiguous by placement of an identical beacon in a different part of the pool. Test trials, in the absence of the platform and the beacons, revealed more persistent searching near the original location of the platform if the beacon attached to the platform had been ambiguous. These results show that learning about the location of the platform, with regard to cues that lie beyond the pool, is influenced by the extent to which an animal can find the platform by relying on other cues. The final experiment shows that this interaction between cues is influenced by an animal's prior experience.

  5. SU-E-J-257: Image Artifacts Caused by Implanted Calypso Beacons in MRI Studies

    SciTech Connect

    Amro, H; Chetty, I; Gordon, J; Wen, N

    2014-06-01

    Purpose: The presence of Calypso Beacon-transponders in patients can cause artifacts during MRI imaging studies. This could be a problem for post-treatment follow up of cancer patients using MRI studies to evaluate metastasis and for functional imaging studies.This work assesses (1) the volume immediately surrounding the transponders that will not be visualized by the MRI due to the beacons, and (2) the dependence of the non-visualized volume on beacon orientation, and scanning techniques. Methods: Two phantoms were used in this study (1) water filled box, (2) and a 2300 cc block of pork meat. Calypso beacons were implanted in the phantoms both in parallel and perpendicular orientations with respect to the MR scanner magnetic field. MR image series of the phantom were obtained with on a 1.0T high field open MR-SIM with multiple pulse sequences, for example, T1-weighted fast field echo and T2-weighted turbo spin echo. Results: On average, a no-signal region with 2 cm radius and 3 cm length was measured. Image artifacts are more significant when beacons are placed parallel to scanner magnetic field; the no-signal area around the beacon was about 0.5 cm larger in orthogonal orientation. The no-signal region surrounding the beacons slightly varies in dimension for the different pulse sequences. Conclusion: The use of Calypso beacons can prohibit the use of MRI studies in post-treatment assessments, especially in the immediate region surrounding the implanted beacon. A characterization of the MR scanner by identifying the no-signal regions due to implanted beacons is essential. This may render the use of Calypso beacons useful for some cases and give the treating physician a chance to identify those patients prior to beacon implantation.

  6. Q-Band (37-41 GHz) Satellite Beacon Architecture for RF Propagation Experiments

    NASA Technical Reports Server (NTRS)

    Simmons, Rainee N.; Wintucky, Edwin G.

    2012-01-01

    In this paper, the design of a beacon transmitter that will be flown as a hosted payload on a geostationary satellite to enable propagation experiments at Q-band (37-41 GHz) frequencies is presented. The beacon uses a phased locked loop stabilized dielectric resonator oscillator and a solid-state power amplifier to achieve the desired output power. The satellite beacon antenna is configured as an offset-fed cut-paraboloidal reflector.

  7. Q-Band (37 to 41 GHz) Satellite Beacon Architecture for RF Propagation Experiments

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Wintucky, Edwin G.

    2014-01-01

    In this paper, the design of a beacon transmitter that will be flown as a hosted payload on a geostationary satellite to enable propagation experiments at Q-band (37 to 41 GHz) frequencies is presented. The beacon uses a phased locked loop stabilized dielectric resonator oscillator and a solid-state power amplifier to achieve the desired output power. The satellite beacon antenna is configured as an offset-fed cutparaboloidal reflector.

  8. Facile synthesis of advanced photodynamic molecular beacon architectures.

    PubMed

    Lovell, Jonathan F; Chen, Juan; Huynh, Elizabeth; Jarvi, Mark T; Wilson, Brian C; Zheng, Gang

    2010-06-16

    Nucleic acid photodynamic molecular beacons (PMBs) are a class of activatable photosensitizers that increase singlet oxygen generation upon binding a specific target sequence. Normally, PMBs are functionalized with multiple solution-phase labeling and purification steps. Here, we make use of a flexible solid-phase approach for completely automated synthesis of PMBs. This enabled the creation of a new type of molecular beacon that uses a linear superquencher architecture. The 3' terminus was labeled with a photosensitizer by generating pyropheophorbide-labeled solid-phase support. The 5' terminus was labeled with up to three consecutive additions of a dark quencher phosphoramidite. These photosensitizing and quenching moieties were stable in the harsh DNA synthesis environment and their hydrophobicity facilitated PMB purification by HPLC. Linear superquenchers exhibited highly efficient quenching. This fully automated synthesis method simplifies not only the synthesis and purification of PMBs, but also the creation of new activatable photosensitizer designs.

  9. Molecular beacons for protein-DNA interaction studies.

    PubMed

    Li, Jun; Cao, Zehui Charles; Tang, Zhiwen; Wang, Kemin; Tan, Weihong

    2008-01-01

    Real-time monitoring of DNA-protein interactions involving molecular beacon (MB) and molecular beacon aptamer (MBA) was discussed in this chapter. MBs are single-stranded oligonucleotide probes with a hairpin structure. MBs have been designed for oligonucleotide recognition and protein-DNA interaction studies. Real-time monitoring of enzymatic reactions, such as cleavage, ligation, and phosphorylation of single-stranded DNA by specific enzyme, has been studied using MBs. Meanwhile, a new generation of molecular probes, MBA, was designed by combining the excellent signal transduction properties of MBs with the specificity of aptamers for protein recognition. Two different aptamers, the one for thrombin and that for platelet-derived growth factor, have been successfully used to construct MBA probes. The interaction between the proteins and the MBA probes was investigated by fluorescence resonance energy transfer, fluorescence anisotropy, and time-resolved fluorescence. This chapter has reviewed our recent progress in this area.

  10. Rayleigh beacon for measuring the surface profile of a radio telescope.

    PubMed

    Padin, S

    2014-12-01

    Millimeter-wavelength Rayleigh scattering from water droplets in a cloud is proposed as a means of generating a bright beacon for measuring the surface profile of a radio telescope. A λ=3  mm transmitter, with an output power of a few watts, illuminating a stratiform cloud, can generate a beacon with the same flux as Mars in 10 GHz bandwidth, but the beacon has a narrow line width, so it is extremely bright. The key advantage of the beacon is that it can be used at any time, and positioned anywhere in the sky, as long as there are clouds.

  11. Rayleigh beacon for measuring the surface profile of a radio telescope.

    PubMed

    Padin, S

    2014-12-01

    Millimeter-wavelength Rayleigh scattering from water droplets in a cloud is proposed as a means of generating a bright beacon for measuring the surface profile of a radio telescope. A λ=3  mm transmitter, with an output power of a few watts, illuminating a stratiform cloud, can generate a beacon with the same flux as Mars in 10 GHz bandwidth, but the beacon has a narrow line width, so it is extremely bright. The key advantage of the beacon is that it can be used at any time, and positioned anywhere in the sky, as long as there are clouds. PMID:25607971

  12. Molecular beacons: a novel DNA probe for nucleic acid and protein studies.

    PubMed

    Tan, W; Fang, X; Li, J; Liu, X

    2000-04-01

    A new concept has been introduced for molecular beacon DNA molecules. Molecular beacons are a new class of oligonucleotides that can report the presence of specific nucleic acids in both homogeneous solutions and at the liquid-solid interface. They emit an intense fluorescent signal only when hybridized to their target DNA or RNA molecules. Biotinylated molecular beacons have been designed and used for the development of ultrasensitive DNA sensors and for DNA molecular interaction studies at a solid-liquid interface. Molecular beacons have also been used to study protein-DNA interactions. They have provided a variety of exciting opportunities in DNA/RNA/protein studies.

  13. Aptamer beacons for visualization of endogenous protein HIV-1 reverse transcriptase in living cells.

    PubMed

    Liang, Yu; Zhang, Zhiping; Wei, Hongping; Hu, Qinxue; Deng, Jiaoyu; Guo, Deyin; Cui, Zongqiang; Zhang, Xian-En

    2011-10-15

    Direct visualization of endogenous proteins in living cells remains a challenge. Aptamer beacon is a promising technique to resolve this problem by combining the excellent protein binding specificity of the aptamer with the sensitive signal transduction mechanism of the molecular beacon. In this study, aptamer 93 del against HIV-1 reverse transcriptase (RT) was engineered into aptamer beacons to recognize and image HIV-1 RT. The constructed aptamer beacons could specifically bind to HIV-1 RT and the beacon-RT binding showed effective fluorescence signal transduction in homogeneous solution. In solutions with 1 μM of the aptamer beacon, the effective fluorescence signal increased with increasing concentration of HIV-1 RT from 0.5 μM to 5 μM. When the aptamer beacons were delivered into the living cells that transiently expressed HIV-1 RT, HIV-1 RT could be specifically labeled and imaged. The designed aptamer beacons were further successfully applied for RT imaging in HIV-1 integrated U1 cells. The method developed here may be extended to visualize many other endogenous proteins in living cells using appropriate aptamer beacons.

  14. Effects of beacon on the rat pituitary-adrenocortical axis response to stress.

    PubMed

    Rucinski, Marcin; Spinazzi, Raffaella; Ziolkowska, Agnieszka; Nussdorfer, Gastone G; Malendowicz, Ludwik K

    2005-08-01

    Beacon is a peptide expressed in the rat hypothalamus and adrenal cortex, which is involved in the central regulation of feeding and inhibits basal and agonist-stimulated glucocorticoid secretion from adrenocortical cells. In vivo studies on beacon have not yet been carried out, and therefore we investigated the effects of a subcutaneous (sc) injection of beacon on the response of rat hypothalamo-pituitary-adrenal axis to stress. Handling and sc injection per se elicited a moderate increase in the plasma concentrations of ACTH and corticosterone, which was counteracted by beacon. Similarly, beacon dampened ACTH and corticosterone responses to ether stress. In contrast, beacon did not affect ACTH response to cold stress, although it was able to induce a moderate lowering in the corticosterone response. Taken together, these findings allow us to draw the following conclusions: i) beacon inhibits handling/injection- and ether stress-activated, but not cold stress-activated, neural mechanism(s) responsible for stimulation of ACTH secretion and the ensuing increase in corticosterone production; and ii) the beacon-induced dampening in corticosterone response to stress also involves a direct inhibitory effect on the adrenal-cortex secretory activity. The physiological relevance of beacon as endogenous anti-stress agent remains to be evaluated.

  15. Development of BEACON technology. Quarterly report, April-June 1982

    SciTech Connect

    Not Available

    1983-03-01

    The BEACON process involves the catalytic deposition of a highly reactive form of carbon from a gas stream which contains carbon monoxide. The carbon-depleted gas is combusted with air to produce power, and the carbon is reacted with steam to produce methane or hydrogen. Experiments were continued this quarter with the objective of improving the carbon deposition efficiency using a Paraho retort off-gas mixture. Analysis has shown that the use of the Paraho off-gas to make hydrogen would be attractive if the ratio of the heat content of the feedgas to the heat content of the hydrogen produced is less than 3. Experimental conditions to achieve this ratio have been established. Recent work had shown that the volume of a BEACON supported catalyst bed increased with an increase in carbon loading level. Four series of experiments were performed where sieve analyses were made after one or more BEACON process cycles. These tests showed that the volume expansion is due to an increase in the number and size of the larger catalyst particles. The bench-scale testing of unsupported catalysts concentrated in two areas: (a) the completion of batch testing in the 4-inch reactor, and (b) the construction of the Tandem Reactor Unit which will permit the transfer of solids between the carbon deposition and steam gasification reactors during testing. It was found that a second stage of steaming enhanced the methane yield. Approximately 80% of the construction and instrumentation of the Tandem Reactor Unit was completed during the quarter. A conceptual design was completed for an Integrated Test Facility (ITF) which would permit research on the BEACON process at a scale sufficient for scale-up. 17 figures, 14 tables.

  16. Integrated Formulation of Beacon-Based Exception Analysis for Multimissions

    NASA Technical Reports Server (NTRS)

    Mackey, Ryan; James, Mark; Park, Han; Zak, Mickail

    2003-01-01

    Further work on beacon-based exception analysis for multimissions (BEAM), a method of real-time, automated diagnosis of a complex electromechanical systems, has greatly expanded its capability and suitability of application. This expanded formulation, which fully integrates physical models and symbolic analysis, is described. The new formulation of BEAM expands upon previous advanced techniques for analysis of signal data, utilizing mathematical modeling of the system physics, and expert-system reasoning,

  17. Molecular beacons in biomedical detection and clinical diagnosis.

    PubMed

    Kim, Youngmi; Sohn, Dosung; Tan, Weihong

    2008-01-01

    Among the diverse nucleic acid probes, molecular beacons (MBs) have shown their excellent potential in a variety of basic researches and practical applications. Their excellent selectivity, sensitivity, and detection without separation have led them to be particularly useful in real-time intracellular monitoring of gene expression, development of biosensors, and clinical diagnostics. This paper will focus on the properties of various MBs and discuss their potential applications.

  18. A two-color, self-controlled molecular beacon.

    PubMed

    Biner, Sarah M; Häner, Robert

    2011-12-16

    Control yourself! A two-color molecular beacon with non-nucleosidic chromophores in a triplex stem is presented. Pyrene and PDI fluorophores act as mutual quenchers by formation of a donor-acceptor complex in the closed form. Hybridization with the target results in two independent fluorescence signals. The two-color read-out provides a "self-control" feature, which helps to eliminate false positive signals in imaging and screening applications.

  19. Caudal spotting in the beacon fish (Hemigrammus ocellifer Characidae).

    PubMed

    Frankel, J S

    2002-01-01

    The beacon fish (Hemigrammus ocellifer) exhibits two phenotypes associated with spotting at the base of the caudal fin, with fish either possessing (H. o. ocellifer) or lacking (H. o. falsus) a prominent red spot in this region. Segregation patterns observed from the progenies of 15 different crosses support a hypothesis that caudal spotting in this species is controlled by a single gene with two alleles, for which the caudal spotting allele is completely dominant.

  20. Detection of Toxoplasma gondii with a DNA molecular beacon probe

    NASA Astrophysics Data System (ADS)

    Zhou, Cun; Xu, Shichao; Yang, Juan; Zhang, Jimei; Dai, Zhao; Zheng, Guo; Sun, Bo; Sun, Shuqing; Feng, Teilin; Zi, Yan; Liang, Chu; Luo, Hao

    2009-07-01

    Toxoplasma gondii is a kind of microscopic parasite that may infect humans, and there are increasing concerns on the early detection of latent Toxoplasma gondii infection in recent years. This research highlights a new type of molecular beacon (MB) fluorescent probe for Toxoplasma DNA testing. We combined high-efficiency fluorescent inorganic core-shell quantum dots-CdTe/ZnS (as fluorescent energy donor) and BHQ-2 (energy acceptor) to the single-strand DNA of Toxoplasma gondii, and a molecular beacon sensing system based on fluorescence resonance energy transfer (FRET) was achieved. Core-shell quantum dots CdTe/ZnS was firstly prepared in aqueous solution, and the influencing factor of its fluorescent properties, including CdTe/Na2S/Zn(CH3COO)2 (v/v), dependence of reaction time, temperature, and pH, is investigated systematically. The synthesized quantum dots and molecular beacon were characterized by transmission electron microscopy (TEM), ultraviolet-visible spectrophotometer (UV-vis), fluorescent spectrophotometer (FS), respectively. The TEM results showed that CdTe/ZnS core-shell quantum dots is ~11nm in size, and the quantum dots is water-soluble well. The sensing ability of target DNA of assembled MB was investigated, and results showed that the target Toxoplasma gonddi DNA can be successfully detected by measuring the change of fluorescence intensity. The results showed that the current sensing probe will be a useful and convenient tool in Toxoplasma gondii early detection.

  1. The Beacon Project: Challenges, Solutions, and Lessons Learned

    NASA Astrophysics Data System (ADS)

    Brook, R. Glenn

    2014-03-01

    With physical limitations imposing increasingly significant performance limitations on future generations of computing hardware, computer architects are turning to increased parallelism and specialized hardware to accelerate key applications and workloads. As a result, emerging high-performance computing (HPC) systems are much more heterogeneous than their predecessors, leading to both operational challenges and application challenges that must be overcome to effectively utilize the associated architectures. With support from the National Science Foundation, the Application Acceleration Center of Excellence (AACE) at the University of Tennessee is currently exploring the impact of the Intel® Xeon Phi™ coprocessor on computational science and engineering through the Beacon Project, an ongoing research project that encompasses the deployment and operation of an energy-efficient supercomputer and the coordination of an associated research program allowing project teams across the country to explore the applicability of the associated architecture to a variety of scientific codes and libraries. This talk presents an overview of encountered challenges along with associated solutions, highlights some of the current results of the application project teams, and summarizes many of the lessons learned through the Beacon Project to date. This material is based upon work supported by the National Science Foundation under Grant Number 1137097 and by the University of Tennessee through the Beacon Project.

  2. Development of BEACON technology. Quarterly report, January-March 1982

    SciTech Connect

    Not Available

    1982-12-01

    The BEACON process involves the catalytic deposition of a highly reactive form of carbon from a gas stream which contains carbon monoxide. The carbon-depleted gas is combusted with air to produce power, and the carbon is reacted with steam to produce methane or hydrogen. Process conditions favoring the production of hydrogen were explored this quarter. Excess steam was found to suppress methane formation, and reduction of catalyst methanation activity was demonstrated. The effect of carbon loading on the physical stability of catalyst C77-K2 and the effect of trace sulfur levels on the chemical stability of the catalyst were examined. The carbon loading tests did not show the catalyst breakup that was expected. Tests of chemical stability of the catalyst in the presence of sulfur-containing gases showed a decline in performance even at levels as low as 4 ppM. Experiments conducted using a Paraho-type oil shale retort offgas as a feedstock showed that acceptable performance could be obtained by removing carbon dioxide from the feedgas. Design of the tandem two reactor system is continuing, along with cold flow testing of the proposed solids transfer system. A simplified thermodynamic analysis of the BEACON process shows that BEACON's increased efficiency over competing processes results from more hot gas going to the turbine with less power required to compress the air for combustion. 16 figures, 13 tables.

  3. A molecular beacon assay for measuring base excision repair activities.

    PubMed

    Maksimenko, Andrei; Ishchenko, Alexander A; Sanz, Guenhaël; Laval, Jacques; Elder, Rhoderick H; Saparbaev, Murat K

    2004-06-18

    The base excision repair (BER) pathway plays a key role in protecting the genome from endogenous DNA damage. Current methods to measure BER activities are indirect and cumbersome. Here, we introduce a direct method to assay DNA excision repair that is suitable for automation and industrial use, based on the fluorescence quenching mechanism of molecular beacons. We designed a single-stranded DNA oligonucleotide labelled with a 5'-fluorescein (F) and a 3'-Dabcyl (D) in which the fluorophore, F, is held in close proximity to the quencher, D, by the stem-loop structure design of the oligonucleotide. Following removal of the modified base or incision of the oligonucleotide, the fluorophore is separated from the quencher and fluorescence can be detected as a function of time. Several modified beacons have been used to validate the assay on both cell-free extracts and purified proteins. We have further developed the method to analyze BER in cultured cells. As described, the molecular beacon-based assay can be applied to all DNA modifications processed by DNA excision/incision repair pathways. Possible applications of the assay are discussed, including high-throughput real-time DNA repair measurements both in vitro and in living cells.

  4. Adapting mobile beacon-assisted localization in wireless sensor networks.

    PubMed

    Teng, Guodong; Zheng, Kougen; Dong, Wei

    2009-01-01

    The ability to automatically locate sensor nodes is essential in many Wireless Sensor Network (WSN) applications. To reduce the number of beacons, many mobile-assisted approaches have been proposed. Current mobile-assisted approaches for localization require special hardware or belong to centralized localization algorithms involving some deterministic approaches due to the fact that they explicitly consider the impreciseness of location estimates. In this paper, we first propose a range-free, distributed and probabilistic Mobile Beacon-assisted Localization (MBL) approach for static WSNs. Then, we propose another approach based on MBL, called Adapting MBL (A-MBL), to increase the efficiency and accuracy of MBL by adapting the size of sample sets and the parameter of the dynamic model during the estimation process. Evaluation results show that the accuracy of MBL and A-MBL outperform both Mobile and Static sensor network Localization (MSL) and Arrival and Departure Overlap (ADO) when both of them use only a single mobile beacon for localization in static WSNs.

  5. Molecular beacons as diagnostic tools: technology and applications.

    PubMed

    Abravaya, Klara; Huff, Jeffrey; Marshall, Ron; Merchant, Barbara; Mullen, Carolyn; Schneider, George; Robinson, John

    2003-04-01

    Molecular beacons are single-stranded, fluorophore-labeled nucleic acid probes that are capable of generating a fluorescent signal in the presence of target, but are dark in the absence of target. Molecular beacons allow multiplex detection of PCR products in real time in a homogeneous assay format. Real time detection is inherently quantitative and affords a greater dynamic range than end-point detection methods. Reactions in a homogeneous assay format are sealed before amplification takes place, providing improved contamination control. A single cycler/reader instrument, coupled with automated sample preparation, results in higher throughput and greater ease of use. A multiplex qualitative assay that detects Chlamydia trachomatis and Neisseria gonorrhoeae, along with an internal control, has been developed. High specificity is achieved through careful selection of primers, probes and assay conditions. Quantitative HIV, HCV, and HBV viral load assays, with sensitivities of 50 copies/ml, 20 IU/ml, and 50 copies/ml, respectively, are achievable. The viral load assays are designed to quantitate all subtype and genotype specimens equivalently. A molecular beacon assay has been designed to detect a single nucleotide polymorphism in the beta2 adrenergic receptor gene.

  6. Pyrene excimer signaling molecular beacons for probing nucleic acids.

    PubMed

    Conlon, Patrick; Yang, Chaoyong James; Wu, Yanrong; Chen, Yan; Martinez, Karen; Kim, Youngmi; Stevens, Nathan; Marti, Angel A; Jockusch, Steffen; Turro, Nicholas J; Tan, Weihong

    2008-01-01

    Molecular beacon DNA probes, containing 1-4 pyrene monomers on the 5' end and the quencher DABCYL on the 3' end, were engineered and employed for real-time probing of DNA sequences. In the absence of a target sequence, the multiple-pyrene labeled molecular beacons (MBs) assumed a stem-closed conformation resulting in quenching of the pyrene excimer fluorescence. In the presence of target, the beacons switched to a stem-open conformation, which separated the pyrene label from the quencher molecule and generated an excimer emission signal proportional to the target concentration. Steady-state fluorescence assays resulted in a subnanomolar limit of detection in buffer, whereas time-resolved signaling enabled low-nanomolar target detection in cell-growth media. It was found that the excimer emission intensity could be scaled by increasing the number of pyrene monomers conjugated to the 5' terminal. Each additional pyrene monomer resulted in substantial increases in the excimer emission intensities, quantum yields, and excited-state lifetimes of the hybridized MBs. The long fluorescence lifetime ( approximately 40 ns), large Stokes shift (130 nm), and tunable intensity of the excimer make this multiple-pyrene moiety a useful alternative to traditional fluorophore labeling in nucleic acid probes.

  7. Pyrene Excimer Signaling Molecular Beacons for Probing Nucleic Acids

    PubMed Central

    Conlon, Patrick; Yang, Chaoyong James; Wu, Yanrong; Chen, Yan; Martinez, Karen; Kim, Youngmi; Stevens, Nathan; Marti, Angel A.; Jockusch, Steffen

    2008-01-01

    Molecular beacon DNA probes, containing one to four pyrene monomers on the 5′ end and the quencher DABCYL on the 3′ end, were engineered and employed for real-time probing of DNA sequences. In the absence of a target sequence, the multiple-pyrene labeled molecular beacons (MBs) assumed a stem-closed conformation resulting in quenching of the pyrene excimer fluorescence. In the presence of target, the beacons switched to a stem-open conformation which separated the pyrene label from the quencher molecule and generated an excimer emission signal proportional to the target concentration. Steady-state fluorescence assays resulted in a sub-nanomolar limit of detection in buffer, while time-resolved signaling enabled low-nanomolar target detection in cell growth media. It was found that the excimer emission intensity could be scaled by increasing the number of pyrene monomers conjugated to the 5′ terminal. Each additional pyrene monomer resulted in substantial increases in the excimer emission intensities, quantum yields, and excited-state lifetimes of the hybridized MBs. The long fluorescence lifetime (~40 ns), large Stokes shift (130 nm), and tunable intensity of the excimer make this multiple-pyrene moiety a useful alternative to traditional fluorophore labeling in nucleic acid probes. In addition, this excimer complex serves as an efficient FRET donor for red-emitting fluorophores, such as TMR, for further extending the Stokes shift of the fluorescent complex. PMID:18078339

  8. Expression of the beacon gene in the rat adrenal gland: direct inhibitory effect of beacon[47-73] on aldosterone secretion from dispersed adrenal zona glomerulosa cells.

    PubMed

    Ziolkowska, Agnieszka; Rucinski, Marcin; Neri, Giuliano; Di Liddo, Rosa; Nussdorfer, Gastone G; Malendowicz, Ludwik K

    2004-02-01

    Beacon gene was recently identified in the rat hypothalamus, and there is evidence that beacon may be involved in the functional regulation of neuroendocrine axes. Reverse transcription-polymerase chain reaction and immunocytochemistry showed the expression of beacon mRNA and protein in the rat adrenal gland, especially in the cortex. Beacon[47-73], at a concentration over 10(-7) M decreased basal aldosterone secretion from dispersed rat zona glomerulosa (ZG) cells, without affecting the ACTH-stimulated one. Basal and agonist-stimulated corticosterone secretion from dispersed zona fasciculata-reticularis cells and catecholamine release from adrenomedullary slices were unaffected by beacon[47-73]. The suppressive effect of beacon[47-73] on aldosterone secretion from ZG cells was abolished by either H-89 or calphostin-C, which are inhibitors of protein kinase A and C signaling cascades. Taken together, these findings allow us to suggest that beacon can be included in the group of regulatory peptides involved in the fine tuning of ZG secretory activity.

  9. Health assessment for Beacon Heights Landfill site, Beacon Falls, Connecticut, Region 1. CERCLIS No. CTD072122062. Addendum. Final report

    SciTech Connect

    Not Available

    1991-06-20

    The Beacon Heights Landfill National Priorities List (NPL) Site is located in Beacon Falls, Connecticut. From the 1920's to 1979, municipal and industrial wastes were disposed of at the landfill. Leachate from the landfill has migrated into the local groundwater aquifers. Two residential wells to the northwest of the site have been contaminated with site-related contaminants. This site is of potential public health concern because of the risk to human health resulting from possible exposure to hazardous substances at concentrations that may result in adverse health effects. As noted in Human Exposure Pathways Section below, human exposure to benzene, chlorobenzene, chloroethane, and methylene chloride may have occurred via ingestion, inhalation, and direct dermal contact with contaminated groundwater. No health study follow-up is indicated at this time.

  10. Superfund Record of Decision (EPA Region 1): Beacon Heights Landfill, Beacon Falls, Connecticut, September 1985. Final report

    SciTech Connect

    Not Available

    1984-09-23

    The Beacon Heights Landfill site is located two miles east of the intersection of Connecticut Routes 8 and 42 in Beacon Falls, Connecticut. From the 1920's until 1970 the site was known as Betkoski's Dump and consisted of approximately six acres on which active dumping occurred. According to records at the Connecticut Department of Environmental Protection (CT DEP), waste accepted at the dump included municipal refuse, rubber, plastics, and industrial chemicals and sludges. Landfill operations consisted primarily of open burning along with burial of noncombustibles. In 1970, the Betkoski property and adjacent properties totaling 83 acres were purchased by the Murtha Trucking Company, and the name was changed to Beacon Heights, Inc. Landfill. At this time, the landfill area was expanded to approximately 30 acres. Records of the CT DEP, including a 1973 report by the landfill engineer, listed rubber, plastics, oils, hydrocarbons, chemical liquids and sludges, and solvents as being disposed of at the landfill by the trucking company. The selected remedial action for this site are included.

  11. Reversible molecular switching of molecular beacon: controlling DNA hybridization kinetics and thermodynamics using mercury(ii) ions.

    PubMed

    Yang, Ronghua; Jin, Jianyu; Long, Liping; Wang, Yongxiang; Wang, Hao; Tan, Weihong

    2009-01-21

    We report that the hydrogen-bonding pattern in a molecular beacon can be replaced by metal-dependent pairs of Hg(2+) and DNA thymine (T) bases. A molecular beacon based on T-Hg(2+)-T exhibits a lower background signal and higher thermostability than regular molecular beacons.

  12. 46 CFR 28.150 - Emergency Position Indicating Radio Beacons (EPIRBs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... beacon (EPIRB) as required by 46 CFR part 25, subpart 25.26. Note: Each vessel which uses radio..., as set forth in 47 CFR part 80. ... 46 Shipping 1 2013-10-01 2013-10-01 false Emergency Position Indicating Radio Beacons (EPIRBs)....

  13. 46 CFR 28.150 - Emergency Position Indicating Radio Beacons (EPIRBs).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... beacon (EPIRB) as required by 46 CFR part 25, subpart 25.26. Note: Each vessel which uses radio..., as set forth in 47 CFR part 80. ... 46 Shipping 1 2010-10-01 2010-10-01 false Emergency Position Indicating Radio Beacons (EPIRBs)....

  14. 46 CFR 169.744 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Emergency position indicating radio beacon (EPIRB). 169.744 Section 169.744 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... position indicating radio beacon (EPIRB). Each EPIRB must be marked with the vessel's name....

  15. 46 CFR 169.831 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Emergency position indicating radio beacon (EPIRB). 169.831 Section 169.831 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... radio beacon (EPIRB). The master shall ensure that— (a) The EPIRB required in § 169.555 of...

  16. Weak beacon detection for air-to-ground optical wireless link establishment.

    PubMed

    Han, Yaoqiang; Dang, Anhong; Tang, Junxiong; Guo, Hong

    2010-02-01

    In an air-to-ground free-space optical communication system, strong background interference seriously affects the beacon detection, which makes it difficult to establish the optical link. In this paper, we propose a correlation beacon detection scheme under strong background interference conditions. As opposed to traditional beacon detection schemes, the beacon is modulated by an m-sequence at the transmitting terminal with a digital differential matched filter (DDMF) array introduced at the receiving end to detect the modulated beacon. This scheme is capable of suppressing both strong interference and noise by correlation reception of the received image sequence. In addition, the DDMF array enables each pixel of the image sensor to have its own DDMF of the same structure to process its received image sequence in parallel, thus it makes fast beacon detection possible. Theoretical analysis and an outdoor experiment have been demonstrated and show that the proposed scheme can realize fast and effective beacon detection under strong background interference conditions. Consequently, the required beacon transmission power can also be reduced dramatically.

  17. The Development of Landmark and Beacon Use in Young Children: Evidence from a Touchscreen Search Task

    ERIC Educational Resources Information Center

    Sutton, Jennifer E.

    2006-01-01

    Children ages 2, 3 and 4 years participated in a novel hide-and-seek search task presented on a touchscreen monitor. On beacon trials, the target hiding place could be located using a beacon cue, but on landmark trials, searching required the use of a nearby landmark cue. In Experiment 1, 2-year-olds performed less accurately than older children…

  18. 46 CFR 28.150 - Emergency Position Indicating Radio Beacons (EPIRBs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... beacon (EPIRB) as required by 46 CFR part 25, subpart 25.26. Note: Each vessel which uses radio..., as set forth in 47 CFR part 80. ... 46 Shipping 1 2014-10-01 2014-10-01 false Emergency Position Indicating Radio Beacons (EPIRBs)....

  19. 46 CFR 169.744 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Emergency position indicating radio beacon (EPIRB). 169.744 Section 169.744 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... position indicating radio beacon (EPIRB). Each EPIRB must be marked with the vessel's name....

  20. 46 CFR 169.555 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Emergency position indicating radio beacon (EPIRB). 169.555 Section 169.555 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... Emergency position indicating radio beacon (EPIRB). (a) Each vessel certificated for exposed waters...

  1. 46 CFR 28.150 - Emergency Position Indicating Radio Beacons (EPIRBs).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... beacon (EPIRB) as required by 46 CFR part 25, subpart 25.26. Note: Each vessel which uses radio..., as set forth in 47 CFR part 80. ... 46 Shipping 1 2012-10-01 2012-10-01 false Emergency Position Indicating Radio Beacons (EPIRBs)....

  2. 46 CFR 169.831 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Emergency position indicating radio beacon (EPIRB). 169.831 Section 169.831 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... radio beacon (EPIRB). The master shall ensure that— (a) The EPIRB required in § 169.555 of...

  3. 46 CFR 169.831 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Emergency position indicating radio beacon (EPIRB). 169.831 Section 169.831 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... radio beacon (EPIRB). The master shall ensure that— (a) The EPIRB required in § 169.555 of...

  4. 46 CFR 28.150 - Emergency Position Indicating Radio Beacons (EPIRBs).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... beacon (EPIRB) as required by 46 CFR part 25, subpart 25.26. Note: Each vessel which uses radio..., as set forth in 47 CFR part 80. ... 46 Shipping 1 2011-10-01 2011-10-01 false Emergency Position Indicating Radio Beacons (EPIRBs)....

  5. Beacon- and Schema-Based Method for Recognizing Algorithms from Students' Source Code

    ERIC Educational Resources Information Center

    Taherkhani, Ahmad; Malmi, Lauri

    2013-01-01

    In this paper, we present a method for recognizing algorithms from students programming submissions coded in Java. The method is based on the concept of "programming schemas" and "beacons". Schemas are high-level programming knowledge with detailed knowledge abstracted out, and beacons are statements that imply specific…

  6. 46 CFR 169.744 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Emergency position indicating radio beacon (EPIRB). 169.744 Section 169.744 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... position indicating radio beacon (EPIRB). Each EPIRB must be marked with the vessel's name....

  7. 46 CFR 169.555 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Emergency position indicating radio beacon (EPIRB). 169.555 Section 169.555 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... Emergency position indicating radio beacon (EPIRB). (a) Each vessel certificated for exposed waters...

  8. 77 FR 41271 - Safety Zone; Newburgh to Beacon Swim, Newburgh, Hudson River, NY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-13

    ... Acronyms DHS Department of Homeland Security FR Federal Register CFR Code of Federal Regulations NPRM... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Newburgh to Beacon Swim, Newburgh, Hudson... Newburgh, NY for the annual Newburgh Beacon Swim event. This temporary safety zone is necessary to...

  9. What Happened to the Beacon Schools? Policy Reform and Educational Equity

    ERIC Educational Resources Information Center

    Smith, Emma

    2015-01-01

    This paper considers the impact of the Beacon schools initiative on the social and academic characteristics of secondary schools in England. The Beacon schools programme ran from 1998 to 2004 and epitomised the (then) Labour government's focus on school improvement through diversity, collaboration and partnership. This paper looks at variation in…

  10. 46 CFR 169.555 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Emergency position indicating radio beacon (EPIRB). 169.555 Section 169.555 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... Emergency position indicating radio beacon (EPIRB). (a) Each vessel certificated for exposed waters...

  11. 46 CFR 169.744 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Emergency position indicating radio beacon (EPIRB). 169.744 Section 169.744 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... position indicating radio beacon (EPIRB). Each EPIRB must be marked with the vessel's name....

  12. 46 CFR 169.831 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Emergency position indicating radio beacon (EPIRB). 169.831 Section 169.831 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... radio beacon (EPIRB). The master shall ensure that— (a) The EPIRB required in § 169.555 of...

  13. 46 CFR 169.555 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Emergency position indicating radio beacon (EPIRB). 169.555 Section 169.555 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... Emergency position indicating radio beacon (EPIRB). (a) Each vessel certificated for exposed waters...

  14. 46 CFR 169.555 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Emergency position indicating radio beacon (EPIRB). 169.555 Section 169.555 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... Emergency position indicating radio beacon (EPIRB). (a) Each vessel certificated for exposed waters...

  15. 46 CFR 169.831 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Emergency position indicating radio beacon (EPIRB). 169.831 Section 169.831 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... radio beacon (EPIRB). The master shall ensure that— (a) The EPIRB required in § 169.555 of...

  16. 46 CFR 169.744 - Emergency position indicating radio beacon (EPIRB).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Emergency position indicating radio beacon (EPIRB). 169.744 Section 169.744 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS... position indicating radio beacon (EPIRB). Each EPIRB must be marked with the vessel's name....

  17. Down-regulation of the beacon gene expression in the regenerating rat adrenal cortex.

    PubMed

    Ziolkowska, Agnieszka; Rucinski, Marcin; Tyczewska, Marianna; Belloni, Anna Sandra; Nowak, Magdalena; Nussdorfer, Gastone G; Malendowicz, Ludwik K

    2006-12-01

    Beacon, a hypothalamic peptide involved in the regulation of food intake, has been recently shown to be expressed in the adrenal cortex, and to inhibit its secretion and growth. To further characterize the role of beacon in the control of adrenal growth, we investigated the level of beacon gene expression in the regenerating rat adrenal cortex. Conventional reverse transcription-polymerase chain reaction (PCR) and immunocytochemistry demonstrated the expression of beacon mRNA and protein in the adrenals at both days 5 and 8 of regeneration after enucleation and contralateral adrenalectomy. Semiquantitative real time-PCR revealed a net down-regulation of beacon mRNA in the regenerating glands, as compared to the intact adrenal cortex of sham-operated animals. Beacon gene expression was higher at day 8 than at day 5 of regeneration. Mitotic index, as assayed by the stachmokinetic method with vincristin, was negligible in the intact adrenal, but greatly elevated in regenerating gland, with a higher index found at day 5 than at day 8 after surgery. Taken together our findings indicate that the level of beacon gene expression is inversely correlated with the proliferative activity of adrenocortical cells, and suggest that beacon might act as an endogenous inhibitor of adrenocortical growth in the rat.

  18. Evaluation of the New York City Beacons. Summary of Phase I Findings.

    ERIC Educational Resources Information Center

    Warren, Constancia

    This report presents findings from Phase 1 of an evaluation of the New York City Beacons initiative, a model of school-community-family partnerships initiated in 1991. Beacons are community centers located in public schools, offering a range of activities and services to participants of all ages, before and after school, in the evenings, and on…

  19. An Oasis in This Desert: Parents Talk about the New York City Beacons.

    ERIC Educational Resources Information Center

    Nevarez, Nancy

    This report presents the findings of focus groups convened to determine what the parents of youth participants in the New York City Beacons think about the program. The Beacons initiative is a comprehensive model of school-community-family partnerships undertaken by New York City in 1991. The initiative originally enabled 10 community-based…

  20. The First Year of Beacon School Status: Maintaining Excellence and Sharing Success.

    ERIC Educational Resources Information Center

    Burton, Neil; Brundrett, Mark

    2000-01-01

    During summer 1998, the British government's Department for Education and Employment recognized 74 schools as model "beacons of excellence." A recent survey reveals that effective communication, coupled with a clear sense of purpose and vision, has enabled Beacon schools to maintain educational excellence while facilitating other schools'…

  1. Immobilization of aptamer-based molecular beacons onto optically-encoded micro-sized beads.

    PubMed

    Jun, Bong-Hyun; Kim, Ji-Eun; Rho, Chul; Byun, Jang-Woong; Kim, Yo Han; Kang, Homan; Kim, Jong-Ho; Kang, Taegyu; Cho, Myung-Haing; Lee, Yoon-Sik

    2011-07-01

    This paper presents a method for the novel immobilization of aptamer-based molecular beacons (apta-beacons) onto optically-encoded micro-sized beads (apta-beacon beads). To immobilize apta-beacons onto flourescently-encoded micro-sized beads, core-shell type beads containing a fluorescent dye-encoded core and apta beacon-coupled shell were prepared. The fluorescent dye-encoded beads were prepared from TentaGel resins by coupling RITC to the amino groups of the core region, after partial protection of amino groups with Fmoc-OSu in a diffusion-controlled manner. After deprotection of the Fmoc-amino groups, FITC-coupled molecular beacons (MBs) were immobilized to the beads together with a quencher by covelent bonding. Briefly, aspartic acid (Asp) was coupled to the shell part of the beads. Then, the quencher was coupled to the N-terminal amino group of Asp and the MBs were coupled to the side chain carboxyl group. In a model study, thrombin was directly detected using this apta-beacon bead method. The thrombin-bound apta-beacon beads were easily recognized by the appearance of fluorescence without any further labeling step.

  2. Use of health information to improve care: the Southern Piedmont Beacon Community Grant.

    PubMed

    Pilkington, William F

    2011-01-01

    In 2009, the Office of the National Coordinator for Health Information Technology solicited proposals to participate in the Beacon Community Program. The program is designed to support communities with established reputations for adopting health information technology solutions. This commentary reviews Community Care of Southern Piedmont, a Beacon Community Program in North Carolina.

  3. Expression of the beacon gene in endocrine glands of the rat.

    PubMed

    Ziolkowska, Agnieszka; Rucinski, Marcin; Di Liddo, Rosa; Nussdorfer, Gastone G; Malendowicz, Ludwik K

    2004-01-01

    Beacon gene has been recently identified in the rat hypothalamus, and reported to be overexpressed in obese animals. This pattern of expression suggests that beacon may be involved in the functional regulation of neuroendocrine axes. Hence, we have investigated the expression of beacon in the endocrine system of the rat. Reverse transcription-polymerase chain reaction showed the expression of beacon mRNA in the hypothalamus, adenohypophysis, thyroid gland, adrenal gland, testis, ovary and pancreatic islets. Immunocytochemistry demonstrated the presence of the beacon immunoreactivity in all tissues studied, the staining being very intense in the neurons of paraventricular and supraoptic nuclei, the basophils of adenohypophysis, the parathyroid gland, adrenocortical cells, testis Leydig cells, ovary thecal, granulosa and lutein cells, and pancreatic islets. Due the fact that beacon has been included in the ubiquitin-like protein family, its widespread expression in rat endocrine tissues is not astonishing. The in vivo administration of beacon[47-73] (3.5 nmol/100 body weight) elicited within 60 min a marked decrease in the plasma concentration of ACTH, aldosterone and corticosterone, and a moderate lowering of the blood levels of testosterone and estradiol. This finding suggests that beacon exerts a negative modulatory action on the pituitary-adrenal axis and gonad secretory activity, whose physiological relevance remains, however, to be established.

  4. Design of a novel molecular beacon: modification of the stem with artificially genetic alphabet.

    PubMed

    Sheng, Pinpin; Yang, Zunyi; Kim, Youngmi; Wu, Yanrong; Tan, Weihong; Benner, Steven A

    2008-11-01

    A molecular beacon that incorporates components of an artificially expanded genetic information system (Aegis) in its stem is shown not to be opened by unwanted stem invasion by adventitious standard DNA; this should improve the "darkness" of the beacon in real-world applications.

  5. Detection of DNA damage by using hairpin molecular beacon probes and graphene oxide.

    PubMed

    Zhou, Jie; Lu, Qian; Tong, Ying; Wei, Wei; Liu, Songqin

    2012-09-15

    A hairpin molecular beacon tagged with carboxyfluorescein in combination with graphene oxide as a quencher reagent was used to detect the DNA damage by chemical reagents. The fluorescence of molecular beacon was quenched sharply by graphene oxide; while in the presence of its complementary DNA the quenching efficiency decreased because their hybridization prevented the strong adsorbability of molecular beacon on graphene oxide. If the complementary DNA was damaged by a chemical reagent and could not form intact duplex structure with molecular beacon, more molecular beacon would adsorb on graphene oxide increasing the quenching efficiency. Thus, damaged DNA could be detected based on different quenching efficiencies afforded by damaged and intact complementary DNA. The damage effects of chlorpyrifos-methyl and three metabolites of styrene such as mandelieaeids, phenylglyoxylieaeids and epoxystyrene on DNA were studied as models. The method for detection of DNA damage was reliable, rapid and simple compared to the biological methods.

  6. Short PNA molecular beacons for real-time PCR allelic discrimination of single nucleotide polymorphisms.

    PubMed

    Petersen, Kenneth; Vogel, Ulla; Rockenbauer, Eszter; Nielsen, Kirsten Vang; Kølvraa, Steen; Bolund, Lars; Nexø, Bjørn

    2004-04-01

    The typing of a single nucleotide polymorphism with DNA probes is sometimes problematic because of the limited discriminating power of long DNA probes. As an alternative to existing assays, we have developed a real-time PCR assay for the genotyping of single nucleotide polymorphisms using short peptide nucleic acid (PNA) molecular beacons. A single nucleotide polymorphism in exon 6 of the XPD gene was chosen as the model system. The genotyping experiments were performed in the ABI 7700 using beacons labeled with either fluorescein or JOE, and in the Lightcycler using a fluorescein labeled beacon. QSY-7 was used as the quencher in all the beacons. The result of the genotyping was the same on both instruments and was in agreement with a previously performed RFLP genotyping of 79 samples. The length of PNA molecular beacons is significantly shorter than that of TaqMan or Lightcycler probes, making probe design and genotype discrimination easier.

  7. Beacon: a novel gene involved in the regulation of energy balance.

    PubMed

    Collier, G R; McMillan, J S; Windmill, K; Walder, K; Tenne-Brown, J; de Silva, A; Trevaskis, J; Jones, S; Morton, G J; Lee, S; Augert, G; Civitarese, A; Zimmet, P Z

    2000-11-01

    The hypothalamus plays a major role in the control of energy balance via the coordination of several neuropeptides and their receptors. We used a unique polygenic animal model of obesity, Psammomys obesus, and performed differential display polymerase chain reaction on hypothalamic mRNA samples to identify novel genes involved in obesity. In this study, we describe a novel gene that encodes a small protein we have termed "beacon." Beacon mRNA gene expression in the hypothalamus was positively correlated with percentage of body fat. Intracerebroventricular infusion of beacon resulted in a dose-dependent increase in food intake and body weight and an increase in hypothalamic expression of neuropeptide Y (NPY). Simultaneous infusion of beacon and NPY significantly potentiated the orexigenic response and resulted in rapid body weight gain. These data suggest a role for beacon in the regulation of energy balance and body weight homeostasis that may be mediated, at least in part, through the NPY pathway.

  8. Digital detection and processing of laser beacon signals for aircraft collision hazard warning

    NASA Technical Reports Server (NTRS)

    Sweet, L. M.; Miles, R. B.; Russell, G. F.; Tomeh, M. G.; Webb, S. G.; Wong, E. Y.

    1981-01-01

    A low-cost collision hazard warning system suitable for implementation in both general and commercial aviation is presented. Laser beacon systems are used as sources of accurate relative position information that are not dependent on communication between aircraft or with the ground. The beacon system consists of a rotating low-power laser beacon, detector arrays with special optics for wide angle acceptance and filtering of solar background light, microprocessors for proximity and relative trajectory computation, and pilot displays of potential hazards. The laser beacon system provides direct measurements of relative aircraft positions; using optimal nonlinear estimation theory, the measurements resulting from the current beacon sweep are combined with previous data to provide the best estimate of aircraft proximity, heading, minimium passing distance, and time to closest approach.

  9. Beacon[47-73] inhibits glucocorticoid secretion and growth of cultured rat and human adrenocortical cells.

    PubMed

    Ziolkowska, Agnieszka; Carraro, Gianni; Rebuffat, Piera; Spinazzi, Raffaella; Nussdorfer, Gastone G; Rucinski, Marcin; Malendowicz, Ludwik K

    2004-09-01

    Evidence has been recently provided that beacon, an ubiquitin-like protein overexpressed in the hypothalamus of Israeli sand rat, is also expressed in several endocrine glands of the Wistar rat, including adrenal cortex. Moreover, it has been shown that the in vivo administration of beacon[47-73] (hereinafter, beacon) evokes within 60 min a marked decrease in the plasma concentrations of ACTH and corticosterone. Hence, we have investigated the effect of beacon (4x10(-9) or 4x10(-7) M) on the secretion and growth of cultured rat and human zona fasciculata/reticularis (ZF/R) cells. Reverse transcription-polymerase chain reaction detected beacon mRNA in all human adrenal cortexes examined. A 3-h exposure to beacon was ineffective, but prolonged (24 and 96 h) exposures significantly lowered basal corticosterone and cortisol secretion from cultured rat and human ZF/R cells, respectively. Moreover, beacon (4x10(-7) M) counteracted the secretagogue action of 10(-8) M ACTH on cultured cells. The 96-h exposure to beacon concentration-dependently decreased basal proliferation rate of cultured cells, without inducing significant changes in the number of apoptotic and necrotic cells. Beacon (4x10(-7) M) significantly inhibited the proliferogenic effect of 10(-8) M adrenomedullin. In light of the involvement of ubiquitin-like proteins in the control of cell cycle and protein sorting and degradation, the hypothesis is advanced that the inhibitory effect of beacon on the secretion and growth of cultured rat ZF/R cells may be connected to its stimulating effect on proteolysis of steroidogenic enzymes and proteins involved in cell replication.

  10. Analysis of measured photon returns from sodium beacons

    SciTech Connect

    Milonni, P.W.; Fugate, R.Q.; Telle, J.M.

    1998-01-01

    We describe an approach to the computation of photon returns from mesospheric sodium beacons excited by laser pulse trains and discuss as specific examples the required numbers of photons for adaptive-optical compensation of atmospheric turbulence. Computed photon return signals are compared with reported measurements for pulses that are long, short, or comparable to the D{sub 2} radiative lifetime (16 ns). Analytical approximations in good agreement with the numerical computations are derived. The results are consistent with experimental data for the different pulse durations. {copyright} 1998 Optical Society of America

  11. Power sources for search and rescue 406 MHz beacons

    NASA Technical Reports Server (NTRS)

    Attia, Alan I.; Perrone, David E.

    1987-01-01

    The results of a study directed at the selection of a commercially available, safe, low cost, light weight and long storage life battery for search and rescue (Sarsat) 406 MHz emergency beacons are presented. In the course of this work, five electrochemical systems (lithium-manganese dioxide, lithium-carbon monofluoride, lithium-silver vanadium oxide, alkaline cells, and cadmium-mercuric oxide) were selected for limited experimental studies to determine their suitability for this application. Two safe, commercially available batteries (lithium-manganese dioxide and lithium-carbon monofluoride) which meet the near term requirements and several alternatives for the long term were identified.

  12. Deep sea AUV navigation using multiple acoustic beacons

    NASA Astrophysics Data System (ADS)

    Ji, Da-xiong; Song, Wei; Zhao, Hong-yu; Liu, Jian

    2016-04-01

    Navigation is a critical requirement for the operation of Autonomous Underwater Vehicles (AUVs). To estimate the vehicle position, we present an algorithm using an extended Kalman filter (EKF) to integrate dead-reckoning position with acoustic ranges from multiple beacons pre-deployed in the operating environment. Owing to high latency, variable sound speed multipath transmissions and unreliability in acoustic measurements, outlier recognition techniques are proposed as well. The navigation algorithm has been tested by the recorded data of deep sea AUV during field operations in a variety of environments. Our results show the improved performance over prior techniques based on position computation.

  13. Molecular Beacon CNT-based Detection of SNPs

    NASA Astrophysics Data System (ADS)

    Egorova, V. P.; Krylova, H. V.; Lipnevich, I. V.; Veligura, A. A.; Shulitsky, B. G.; Y Fedotenkova, L.

    2015-11-01

    An fluorescence quenching effect due to few-walled carbon nanotubes chemically modified by carboxyl groups has been utilized to discriminate Single Nucleotide Polymorphism (SNP). It was shown that the complex obtained from these nanotube and singlestranded primer DNA is formed due to stacking interactions between the hexagons of the nanotubes and aromatic rings of nucleotide bases as well as due to establishing of hydrogen bonds between acceptor amine groups of nucleotide bases and donor carboxyl groups of the nanotubes. It has been demonstrated that these complexes may be used to make highly effective DNA biosensors detecting SNPs which operate as molecular beacons.

  14. Towards single-spot multianalyte molecular beacon biosensors.

    PubMed

    Strohsahl, Christopher M; Du, Hui; Miller, Benjamin L; Krauss, Todd D

    2005-09-15

    The separate developments of microarray patterning of DNA oligonucleotides, and of DNA hairpins as sensitive probes for oligonucleotide identification in solution, have had a tremendous impact on basic biological research and clinical applications. Herein, we will discuss several successful efforts to develop oligonucleotide sensors based on the surface immobilization of functionalized DNA hairpins. We also will discuss the development of prototypical single-spot multianalyte "Molecular Beacon" biosensors. Importantly, we show that organic fluorophores will likely be inadequate in moving this technology forward and new approaches, such as the use of nanotechnology, will be needed.

  15. Laser beacon system for aircraft collision hazard determination.

    PubMed

    Miles, R B

    1980-07-01

    A laser beacon collision hazard determination system is capable of simultaneously determining range, bearing, and heading of threat aircraft. Calculations demonstrate that threat aircraft may be observed at > 10 km under good visibility conditions. When the visibility is limited to 5.6 km (3 nautical miles), the shortest possible warning time for aircraft below 3000 m (10,000 ft) can be > 15 sec. A wide variety of detection systems may be chosen based on cost, detection range, and sophistication. Traffic saturation is not a problem since closer aircraft produce easily distinguishable signals so traffic may be prioritized. Preliminary tests demonstrate that accurate range measurements are possible under daylight conditions.

  16. A graphene-enhanced molecular beacon for homogeneous DNA detection.

    PubMed

    Li, Fan; Huang, Yan; Yang, Qing; Zhong, Zentao; Li, Di; Wang, Lihua; Song, Shiping; Fan, Chunhai

    2010-06-01

    In this work, we report the design of a novel graphene-based molecular beacon (MB) that could sensitively and selectively detect specific DNA sequences. The ability of water-soluble graphene oxide (GO) to differentiated hairpin and dsDNA offered a new approach to detect DNA. We found that the background fluorescence of MB was significantly suppressed in the presence of GO, which increased the signal-to-background ratio, hence the sensitivity. Moreover, the single-mismatch differentiation ability of hairpin DNA was maintained, leading to high selectivity of this new method.

  17. Laser beacon wave-front sensing without focal anisoplanatism.

    PubMed

    Buscher, D F; Love, G D; Myers, R M

    2002-02-01

    Wave-front sensing from artificial beacons is normally performed by formation of a focused spot in the atmosphere and sensing of the wave-front distortions produced during the beam's return passage. We propose an alternative method that senses the distortions produced during the outgoing path by forming an intensity pattern in the atmosphere that is then viewed from the ground. A key advantage of this method is that a parallel beam is used, and therefore the wave-front measurements will not suffer from the effects of focal anisoplanatism. We also envisage other geometries, all based on the concept of projecting a pupil pattern onto the atmosphere.

  18. Real-time monitoring in vitro transcription using molecular beacons.

    PubMed

    Liu, Jianwei; Feldman, Patricia; Chung, Thomas D Y

    2002-01-01

    A homogeneous fluorescence-based molecular beacon (MB) method has been developed for real-time monitoring of in vitro transcription reactions. MB probes are structured as target-specific antisense oligodeoxynucleotides containing a proximate fluorophore-quencher pair. Upon binding to its target sequence, the probe undergoes a structural rearrangement that separates the proximate pair, thus dequenching fluorescence. We demonstrate that this simple, inexpensive, rapid, and homogeneous fluorescence-based assay permits real-time monitoring of in vitro transcription and end-point measurement of RNA. The results from the RNA MB assay were comparable to those from other methods.

  19. Laser beacon adaptive optics for power beaming applications

    SciTech Connect

    Fugate, R.Q.

    1994-12-31

    This paper discusses the laser beam control system requirements for power beaming applications. Power beaming applications include electric and thermal engine propulsion for orbit transfer, station changing, and recharging batteries. Beam control includes satellite acquisition, high accuracy tracking, higher order atmospheric compensation using adaptive optics, and precision point-ahead. Beam control may also include local laser beam clean-up with a low order adaptive optics system. This paper also presents results of tracking and higher-order correction experiments on astronomical objects. The results were obtained with a laser beacon adaptive optics system at Phillips Laboratory`s Starfire Optical Range near Albuquerque, NM. At a wavelength of 0.85 {mu}m, the author has achieved Strehl ratios of {approximately}0.50 using laser beacons and {approximately}0.65 using natural stars for exposures longer than one minute on objects of {approximately}8{sup th} magnitude. The resulting point spread function has a full width half maximum (FWHM) of 0.13 arcsec.

  20. Rapid DNA detection by beacon-assisted detection amplification.

    PubMed

    Connolly, Ashley R; Trau, Matt

    2011-06-01

    This protocol describes a new and rapid isothermal reaction process designed to amplify and detect a specific DNA sequence in purified DNA extracted from cultured cells. The protocol uses a DNA nanomachine that comprises two molecular switches that function in concert to isothermally amplify and detect a DNA target. First, a molecular beacon detection switch is 'activated' only if a DNA target sequence is present. A DNA primer and DNA polymerase are used to lock the beacon in an activated conformation. Second, an amplification and signal-transduction switch is initiated following successful activation. A nicking endonuclease and the DNA polymerase are used to replicate the DNA target. Both switches operate simultaneously at 40 °C in a single reaction to rapidly generate multiple copies of the DNA target in a cyclic polymerization reaction. This protocol enables femtomole amounts of a DNA target to be reproducibly amplified and detected in <40 min. We demonstrate the successful use of this protocol in assays containing synthetic DNA components and purified DNA extracted from biological samples.

  1. Molecular aptamer beacons for real-time protein recognition.

    PubMed

    Li, Jianwei J; Fang, Xiaohong; Tan, Weihong

    2002-03-22

    One of the most pressing problems facing those attempting to understand the regulation of gene expression and translation is the necessity to monitor protein production in a variety of metabolic states. Thus far, there is no easy solution that will either identify or quantitate proteins in real time. Here we introduce a novel protein probe, molecular aptamer beacon (MAB), for real time protein recognition and quantitative analysis. The MAB combines the signal transduction mechanism of molecular beacons and the molecular recognition specificity of aptamers. An MAB based on a thrombin-binding aptamer was prepared as a model to demonstrate the feasibility. Significant fluorescent signal change was observed when MAB was bound to thrombin, which is attributed to a significant conformational change in MAB from a loose random coil to a compact unimolecular quadruplex. The MAB recognizes its target protein with high specificity and high sensitivity (112 picomolar thrombin concentration) in homogeneous solutions. Ratiometric imaging has been conducted with MAB labeled with two fluorophores, which makes it feasible for protein quantitation in living specimen. The unique properties of the MAB will enable the development of a class of protein probes for real time protein tracing in living specimen and for efficient biomedical diagnosis in homogeneous solutions.

  2. Molecular-beacon-based array for sensitive DNA analysis.

    PubMed

    Yao, Gang; Tan, Weihong

    2004-08-15

    Molecular beacon (MB) DNA probes provide a new way for sensitive label-free DNA/protein detection in homogeneous solution and biosensor development. However, a relatively low fluorescence enhancement after the hybridization of the surface-immobilized MB hinders its effective biotechnological applications. We have designed new molecular beacon probes to enable a larger separation between the surface and the surface-bound MBs. Using these MB probes, we have developed a DNA array on avidin-coated cover slips and have improved analytical sensitivity. A home-built wide-field optical setup was used for imaging the array. Our results show that linker length, pH, and ionic strength have obvious effects on the performance of the surface-bound MBs. The fluorescence enhancement of the new MBs after hybridization has been increased from 2 to 5.5. The MB-based DNA array could be used for DNA detection with high sensitivity, enabling simultaneous multiple-target bioanalysis in a variety of biotechnological applications.

  3. Beacon-like immunoreactivity in the hypothalamus of domestic chick.

    PubMed

    Esposito, V; de Girolamo, P; Gargiulo, G; Dun, N J

    2006-12-01

    Beacon-immunoreactive (B-ir) fibres and neurons in the hypothalamus of the domestic chick (Gallus domesticus) were studied using an immunohistochemical technique in order to verify the presence and elucidate the pattern of distribution of this novel peptide in an avian brain. B-ir neurons were seen in the n. supraopticus, pars ventralis and pars externus; n. magnocellularis preopticus, pars dorsalis, medialis and ventralis; n. preopticus periventricularis; n. suprachiasmaticus, pars medialis; n. ventrolateralis thalami. Only few B-ir cells were scattered in the most anterior part of the lateral hypothalamic area. B-ir fibres, appearing as thin punctuate structures, were seen mainly along the walls of the third ventricle and in the ventromedial hypothalamus. Labelled fibres and terminals were located in the external and internal zones of the anterior and posterior median eminence. In particular, fibre terminals were seen close to the capillary loops of the hypothalamo-hypophysial portal system. The anatomical data of the present study regarding the distribution of B-ir in the chick hypothalamus suggest that beacon may play a key role in the regulation of the neuroendocrine system by acting as a neuromodulator and/or neurotransmitter.

  4. Molecular Beacons: Powerful Tools for Imaging RNA in Living Cells

    PubMed Central

    Monroy-Contreras, Ricardo; Vaca, Luis

    2011-01-01

    Recent advances in RNA functional studies highlights the pivotal role of these molecules in cell physiology. Diverse methods have been implemented to measure the expression levels of various RNA species, using either purified RNA or fixed cells. Despite the fact that fixed cells offer the possibility to observe the spatial distribution of RNA, assays with capability to real-time monitoring RNA transport into living cells are needed to further understand the role of RNA dynamics in cellular functions. Molecular beacons (MBs) are stem-loop hairpin-structured oligonucleotides equipped with a fluorescence quencher at one end and a fluorescent dye (also called reporter or fluorophore) at the opposite end. This structure permits that MB in the absence of their target complementary sequence do not fluoresce. Upon binding to targets, MBs emit fluorescence, due to the spatial separation of the quencher and the reporter. Molecular beacons are promising probes for the development of RNA imaging techniques; nevertheless much work remains to be done in order to obtain a robust technology for imaging various RNA molecules together in real time and in living cells. The present work concentrates on the different requirements needed to use successfully MB for cellular studies, summarizing recent advances in this area. PMID:21876785

  5. DNA aptamer beacon assay for C-telopeptide and handheld fluorometer to monitor bone resorption.

    PubMed

    Bruno, John Gordon; Carrillo, Maria P; Phillips, Taylor; Hanson, Douglas; Bohmann, Jonathan A

    2011-09-01

    A novel DNA aptamer beacon is described for quantification of a 26-amino acid C-telopeptide (CTx) of human type I bone collagen. One aptamer sequence and its reverse complement dominated the aptamer pool (31.6% of sequenced clones). Secondary structures of these aptamers were examined for potential binding pockets. Three-dimensional computer models which analyzed docking topologies and binding energies were in agreement with empirical fluorescence experiments used to select one candidate loop for beacon assay development. All loop structures from the aptamer finalists were end-labeled with TYE 665 and Iowa Black quencher for comparison of beacon fluorescence levels as a function of CTx concentration. The optimal beacon, designated CTx 2R-2h yielded a low ng/ml limit of detection using a commercially available handheld fluorometer. The CTx aptamer beacon bound full-length 26-amino acid CTx peptide, but not a shorter 8-amino acid segment of CTx peptide which is a common target for commercial CTx ELISA kits. The prototype assay was shown to detect CTx peptide from human urine after creatinine and urea were removed by size-exclusion chromatography to prevent nonspecific denaturing of the aptamer beacon. This work demonstrates the potential of aptamer beacons to be utilized for rapid and sensitive bone health monitoring in a handheld or point-of-care format.

  6. Detection of MDR1 mRNA expression with optimized gold nanoparticle beacon

    NASA Astrophysics Data System (ADS)

    Zhou, Qiumei; Qian, Zhiyu; Gu, Yueqing

    2016-03-01

    MDR1 (multidrug resistance gene) mRNA expression is a promising biomarker for the prediction of doxorubicin resistance in clinic. However, the traditional technical process in clinic is complicated and cannot perform the real-time detection mRNA in living single cells. In this study, the expression of MDR1 mRNA was analyzed based on optimized gold nanoparticle beacon in tumor cells. Firstly, gold nanoparticle (AuNP) was modified by thiol-PEG, and the MDR1 beacon sequence was screened and optimized using a BLAST bioinformatics strategy. Then, optimized MDR1 molecular beacons were characterized by transmission electron microscope, UV-vis and fluorescence spectroscopies. The cytotoxicity of MDR1 molecular beacon on L-02, K562 and K562/Adr cells were investigated by MTT assay, suggesting that MDR1 molecular beacon was low inherent cytotoxicity. Dark field microscope was used to investigate the cellular uptake of hDAuNP beacon assisted with ultrasound. Finally, laser scanning confocal microscope images showed that there was a significant difference in MDR1 mRNA expression in K562 and K562/Adr cells, which was consistent with the results of q-PCR measurement. In summary, optimized MDR1 molecular beacon designed in this study is a reliable strategy for detection MDR1 mRNA expression in living tumor cells, and will be a promising strategy for in guiding patient treatment and management in individualized medication.

  7. Pedestrian and motorists' actions at pedestrian hybrid beacon sites: findings from a pilot study.

    PubMed

    Pulugurtha, Srinivas S; Self, Debbie R

    2015-01-01

    This paper focuses on an analysis of pedestrian and motorists' actions at sites with pedestrian hybrid beacons and assesses their effectiveness in improving the safety of pedestrians. Descriptive and statistical analyses (one-tail two-sample T-test and two-proportion Z-test) were conducted using field data collected during morning and evening peak hours at three study sites in the city of Charlotte, NC, before and after the installation of pedestrian hybrid beacons. Further, an analysis was conducted to assess the change in pedestrian and motorists' actions over time (before the installation; 1 month, 3 months, 6 months, and 12 months after the installation). Results showed an increase in average traffic speed at one of the pedestrian hybrid beacon sites while no specific trends were observed at the other two pedestrian hybrid beacon sites. A decrease in the number of motorists not yielding to pedestrians, pedestrians trapped in the middle of the street, and pedestrian-vehicle conflicts were observed at all the three pedestrian hybrid beacon sites. The installation of pedestrian hybrid beacons did not have a negative effect on pedestrian actions at two out of the three sites. Improvements seem to be relatively more consistent 3 months after the installation of the pedestrian hybrid beacon.

  8. Gold nanoparticle fluorescent molecular beacon for low-resolution DQ2 gene HLA typing.

    PubMed

    Beni, Valerio; Zewdu, Taye; Joda, Hamdi; Katakis, Ioanis; O'Sullivan, Ciara K

    2012-01-01

    Coeliac disease is an inflammation of the small intestine triggered by gluten ingestion. We present a fluorescent genosensor, exploiting molecular-beacon-functionalized gold nanoparticles, for the identification of human leukocyte antigen (HLA) DQ2 gene, a key genetic factor in coeliac disease. Optimization of sensor performance was achieved by tuning the composition of the oligonucleotide monolayer immobilized on the gold nanoparticle and the molecular beacon design. Co-immobilization of the molecular beacon with a spacing oligonucleotide (thiolated ten-thymine oligonucleotide) in the presence of ten-adenine oligonucleotides resulted in a significant increase of the sensor response owing to improved spacing of the molecular beacons and extension of the distance from the nanoparticle surface, which renders them more available for recognition. Further increase in the response (approximately 40%) was shown to be achievable when the recognition sequence of the molecular beacon was incorporated in the stem. Improvement of the specificity of the molecular beacons was also achieved by the incorporation within their recognition sequence of a one-base mismatch. Finally, gold nanoparticles functionalized with two molecular beacons targeting the DQA1*05* and DQB1*02* alleles allowed the low-resolution typing of the DQ2 gene at the nanomolar level.

  9. Highly selective single nucleotide polymorphism recognition by a chiral (5S) PNA beacon.

    PubMed

    Totsingan, Filbert; Tedeschi, Tullia; Sforza, Stefano; Corradini, Roberto; Marchelli, Rosangela

    2009-01-01

    A chiral peptide nucleic acid (PNA) beacon containing a C-5 modified monomer based on L-lysine was synthesized. The terminal amino group of the lysine side chain was linked to a spacer for future applications on surfaces. The PNA beacon bears a carboxyfluorescein fluorophore and a dabcyl quencher at opposite ends. The DNA binding properties were compared with those of a homologous PNA beacon containing only achiral monomers. Both beacons underwent a fluorescence increase in the presence of complementary DNA, with higher efficiency and higher selectivity (evaluated using single mismatched DNA sequences) observed for the chiral monomer containing PNA. Ion exchange (IE) HPLC with fluorimetric detection was used in combination with the beacon for the selective detection of complementary DNA. A fluorescent peak corresponding to the PNA beacon:DNA duplex was observed at a very low detection limit (1 nM). The discriminating capacity of the chiral PNA beacon for a single mismatch was found to be superior to those observed with the unmodified one, thus confirming the potency of chirality for increasing the affinity and specificity of DNA recognition.

  10. Fast molecular beacon hybridization in organic solvents with improved target specificity.

    PubMed

    Dave, Neeshma; Liu, Juewen

    2010-12-01

    DNA hybridization is of tremendous importance in biology, bionanotechnology, and biophysics. Molecular beacons are engineered DNA hairpins with a fluorophore and a quencher labeled on each of the two ends. A target DNA can open the hairpin to give an increased fluorescence signal. To date, the majority of molecular beacon detections have been performed only in aqueous buffers. We describe herein DNA detection in nine different organic solvents, methanol, ethanol, isopropanol, acetonitrile, formamide, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), ethylene glycol, and glycerol, varying each up to 75% (v/v). In comparison with detection in water, the detection in organic solvents showed several important features. First, the molecular beacon hybridizes to its target DNA in the presence of all nine solvents up to a certain percentage. Second, the rate of this hybridization was significantly faster in most organic solvents compared with water. For example, in 56% ethanol, the beacon showed a 70-fold rate enhancement. Third, the ability of the molecular beacon to discriminate single-base mismatch is still maintained. Lastly, the DNA melting temperature in the organic solvents showed a solvent concentration-dependent decrease. This study suggests that molecular beacons can be used for applications where organic solvents must be involved or organic solvents can be intentionally added to improve the molecular beacon performance.

  11. The use of molecular beacons to detect and quantify microRNA.

    PubMed

    Baker, Meredith B; Bao, Gang; Searles, Charles D

    2013-01-01

    Molecular beacons are oligonucleotide (DNA or RNA) probes that have become increasingly important tools for RNA sensitive detection both in vitro and in living cells. From their inception, molecular beacons have been used to determine the expression levels of RNA transcripts, but they also have the specificity to identify splice variants and single-nucleotide polymorphisms. Our group has performed extensive studies on molecular beacon design, molecular beacon hybridization assays, and cellular imaging of mRNA molecules. Compared to other methods for assessing RNA transcript expression, such as qRT-PCR, the beacon-based approach is potentially simpler, faster, more cost effective, and more specific. Recently, our group demonstrated that molecular beacons can readily distinguish mature- and precursor microRNAs, and reliably quantify microRNA expression. MicroRNAs (miRNAs) are a class of short (19-25 nt), single-stranded, noncoding RNAs that regulate an array of cellular functions through the degradation and translational repression of mRNA targets. Importantly, tissue levels of specific miRNAs have been shown to correlate with pathological development of diseases. Thus, a rapid and efficient method of assessing miRNA expression is useful for diagnosing diseases and identifying novel therapeutic targets. Here, we describe the methods for designing and using molecular beacons to detect and quantify miRNA.

  12. Adaptive-optics compensation by distributed beacons for non-kolmogorov turbulence.

    PubMed

    Rao, C; Jiang, W; Ling, N

    2001-07-20

    In optical propagation through atmospheric turbulence, the performance of compensation with adaptive optics depends on a beacon's spatial distribution. With distributed beacons, the inefficiency of the modal correction, which is defined as the ratio of the anisoplanatic error of the jth mode and the Zernike-coefficient variance, is derived by use of the wave-front expansion on the Zernike polynomials for non-Kolmogorov turbulence. Numerical results are presented for laser beam propagation through constant turbulence with an offset point beacon and an on-axis uniform circular beacon. The results show that compensation for an on-axis uniform circular beacon is much more effective than that for an offset point beacon. The low-order modes are much more correlated than the higher-order modes. The larger the power-law exponent of the refractive-index power spectrum beta, the smaller the propagation path length L and the larger the diameter D of the telescope aperture, the more effective the compensation is. For a specific extended degree of beacon for which there are a maximum number of modes N(max) to be corrected, only low-order-correction systems are useful.

  13. Preliminary performance analysis of an interplanetary navigation system using asteroid based beacons

    NASA Technical Reports Server (NTRS)

    Jee, J. Rodney; Khatib, Ahmad R.; Muellerschoen, Ronald J.; Williams, Bobby G.; Vincent, Mark A.

    1988-01-01

    A futuristic interplanetary navigation system using transmitters placed on selected asteroids is introduced. This network of space beacons is seen as a needed alternative to the overly burdened Deep Space Network. Covariance analyses on the potential performance of these space beacons located on a candidate constellation of eight real asteroids are initiated. Simplified analytic calculations are performed to determine limiting accuracies attainable with the network for geometric positioning. More sophisticated computer simulations are also performed to determine potential accuracies using long arcs of range and Doppler data from the beacons. The results from these computations show promise for this navigation system.

  14. Fluorescent nanoparticle beacon for logic gate operation regulated by strand displacement.

    PubMed

    Yang, Jing; Shen, Lingjing; Ma, Jingjing; Schlaberg, H Inaki; Liu, Shi; Xu, Jin; Zhang, Cheng

    2013-06-26

    A mechanism is developed to construct a logic system by employing DNA/gold nanoparticle (AuNP) conjugates as a basic work unit, utilizing a fluorescent beacon probe to detect output signals. To implement the logic circuit, a self-assembly DNA structure is attached onto nanoparticles to form the fluorescent beacon. Moreover, assisted by regulation of multilevel strand displacement, cascaded logic gates are achieved. The computing results are detected by methods using fluorescent signals, gel electrophoresis and transmission electron microscope (TEM). This work is expected to demonstrate the feasibility of the cascaded logic system based on fluorescent nanoparticle beacons, suggesting applications in DNA computation and biotechnology.

  15. High-throughput bead-based identification of structure-switching aptamer beacons.

    PubMed

    Trevino, Simon G; Levy, Matthew

    2014-09-01

    We describe a new platform to identify structure-switching DNA beacon aptamers, which detect small molecules in a specific manner. By clonally amplifying a DNA library designed to fluoresce in response to binding events onto microbeads, aptamer beacons can be selected by stringent fluorescence-assisted sorting. We validated this method by isolating known and novel anti-steroid aptamers from two separate DNA libraries that were structurally enriched with three-way junctions. Importantly, aptamers were retrieved in only a few (three) rounds of selection by this approach and did not require further optimization, significantly streamlining the process of beacon development.

  16. The development of landmark and beacon use in young children: evidence from a touchscreen search task.

    PubMed

    Sutton, Jennifer E

    2006-01-01

    Children ages 2, 3 and 4 years participated in a novel hide-and-seek search task presented on a touchscreen monitor. On beacon trials, the target hiding place could be located using a beacon cue, but on landmark trials, searching required the use of a nearby landmark cue. In Experiment 1, 2-year-olds performed less accurately than older children on landmark trials but performed equivalently on beacon trials. In Experiment 2, the number of items on the screen was reduced and 2-year-olds' performance improved. Use of the landmark transformation technique in Experiment 3 revealed that older children formed a more precise landmark-target spatial relationship than 2-year-olds. Experiment 4 showed that the transformation itself was not responsible for the youngest participants' decreased accuracy in Experiment 3. Overall, beacons were utilized effectively by all participants, but the use of landmark cues is refined between the ages of 2 and 4.

  17. Highly sensitive and rapid bacteria detection using molecular beacon-Au nanoparticles hybrid nanoprobes.

    PubMed

    Cao, Jing; Feng, Chao; Liu, Yan; Wang, Shouyu; Liu, Fei

    2014-07-15

    Since many diseases are caused by pathogenic bacterial infections, accurate and rapid detection of pathogenic bacteria is in urgent need to timely apply appropriate treatments and to reduce economic costs. To end this, we designed molecular beacon-Au nanoparticle hybrid nanoprobes to improve the bacterial detection efficiency and sensitivity. Here, we show that the designed molecular beacon modified Au nanoparticles could specifically recognize synthetic DNAs targets and can readily detect targets in clinical samples. Moreover, the hybrid nanoprobes can recognize Escherichia coli within an hour at a concentration of 10(2) cfu/ml, which is 1000-folds sensitive than using molecular beacon directly. Our results show that the molecular beacon-Au nanoparticle hybrid nanoprobes have great potential in medical and biological applications.

  18. Chemically directing d-block heterometallics to nanocrystal surfaces as molecular beacons of surface structure

    SciTech Connect

    Rosen, Evelyn L.; Gilmore, Keith; Sawvel, April M.; Hammack, Aaron T.; Doris, Sean E.; Aloni, Shaul; Altoe, Virginia; Nordlund, Dennis; Weng, Tsu -Chien; Sokaras, Dimosthenis; Cohen, Bruce E.; Urban, Jeffrey J.; Ogletree, D. Frank; Milliron, Delia J.; Prendergast, David; Helms, Brett A.

    2015-07-28

    Our understanding of structure and bonding in nanoscale materials is incomplete without knowledge of their surface structure. Needed are better surveying capabilities responsive not only to different atoms at the surface, but also their respective coordination environments. We report here that d-block organometallics, when placed at nanocrystal surfaces through heterometallic bonds, serve as molecular beacons broadcasting local surface structure in atomic detail. This unique ability stems from their elemental specificity and the sensitivity of their d-orbital level alignment to local coordination environment, which can be assessed spectroscopically. Re-surfacing cadmium and lead chalcogenide nanocrystals with iron- or ruthenium-based molecular beacons is readily accomplished with trimethylsilylated cyclopentadienyl metal carbonyls. For PbSe nanocrystals with iron-based beacons, we show how core-level X-ray spectroscopies and DFT calculations enrich our understanding of both charge and atomic reorganization at the surface when beacons are bound.

  19. Chemically directing d-block heterometallics to nanocrystal surfaces as molecular beacons of surface structure

    DOE PAGESBeta

    Rosen, Evelyn L.; Gilmore, Keith; Sawvel, April M.; Hammack, Aaron T.; Doris, Sean E.; Aloni, Shaul; Altoe, Virginia; Nordlund, Dennis; Weng, Tsu -Chien; Sokaras, Dimosthenis; et al

    2015-07-28

    Our understanding of structure and bonding in nanoscale materials is incomplete without knowledge of their surface structure. Needed are better surveying capabilities responsive not only to different atoms at the surface, but also their respective coordination environments. We report here that d-block organometallics, when placed at nanocrystal surfaces through heterometallic bonds, serve as molecular beacons broadcasting local surface structure in atomic detail. This unique ability stems from their elemental specificity and the sensitivity of their d-orbital level alignment to local coordination environment, which can be assessed spectroscopically. Re-surfacing cadmium and lead chalcogenide nanocrystals with iron- or ruthenium-based molecular beacons ismore » readily accomplished with trimethylsilylated cyclopentadienyl metal carbonyls. For PbSe nanocrystals with iron-based beacons, we show how core-level X-ray spectroscopies and DFT calculations enrich our understanding of both charge and atomic reorganization at the surface when beacons are bound.« less

  20. GaAs monolithic R.F. modules for SARSAT distress beacons

    NASA Technical Reports Server (NTRS)

    Cauley, Michael A.

    1991-01-01

    Monolithic GaAs UHF components for use in SARSAT Emergency Distress beacons are under development by Microwave Monolithics, Inc., Simi Valley, CA. The components include a bi-phase modulator, driver amplifier, and a 5 watt power amplifier.

  1. Hybrid diagnostic system: beacon-based exception analysis for multimissions - Livingstone integration

    NASA Technical Reports Server (NTRS)

    Park, Han G.; Cannon, Howard; Bajwa, Anupa; Mackey, Ryan; James, Mark; Maul, William

    2004-01-01

    This paper describes the initial integration of a hybrid reasoning system utilizing a continuous domain feature-based detector, Beacon-based Exceptions Analysis for Multimissions (BEAM), and a discrete domain model-based reasoner, Livingstone.

  2. Genotyping single nucleotide polymorphisms using different molecular beacon multiplexed within a suspended core optical fiber.

    PubMed

    Nguyen, Linh Viet; Giannetti, Sara; Warren-Smith, Stephen; Cooper, Alan; Selleri, Stefano; Cucinotta, Annamaria; Monro, Tanya

    2014-01-01

    We report a novel approach to genotyping single nucleotide polymorphisms (SNPs) using molecular beacons in conjunction with a suspended core optical fiber (SCF). Target DNA sequences corresponding to the wild- or mutant-type have been accurately recognized by immobilizing two different molecular beacons on the core of a SCF. The two molecular beacons differ by one base in the loop-probe and utilize different fluorescent indicators. Single-color fluorescence enhancement was obtained when the immobilized SCFs were filled with a solution containing either wild-type or mutant-type sequence (homozygous sample), while filling the immobilized SCF with solution containing both wild- and mutant-type sequences resulted in dual-color fluorescence enhancement, indicating a heterozygous sample. The genotyping was realized amplification-free and with ultra low-volume for the required DNA solution (nano-liter). This is, to our knowledge, the first genotyping device based on the combination of optical fiber and molecular beacons.

  3. A graphene oxide-based nano-beacon for DNA phosphorylation analysis.

    PubMed

    Wu, Wenhe; Hu, Haiyan; Li, Fan; Wang, Lihua; Gao, Jimin; Lu, Jianxin; Fan, Chunhai

    2011-01-28

    We designed a single-fluorophore-tagged hairpin-structured nano-beacon probe by using a superquencher, graphene oxide (GO), based on which a new method for the analysis of DNA phosphorylation detection was developed.

  4. Real-time monitoring of rolling-circle amplification using a modified molecular beacon design.

    PubMed

    Nilsson, Mats; Gullberg, Mats; Dahl, Fredrik; Szuhai, Karoly; Raap, Anton K

    2002-07-15

    We describe a method to monitor rolling-circle replication of circular oligonucleotides in dual-color and in real-time using molecular beacons. The method can be used to study the kinetics of the polymerization reaction and to amplify and quantify circularized oligonucleotide probes in a rolling-circle amplification (RCA) reaction. Modified molecular beacons were made of 2'-O-Me-RNA to prevent 3' exonucleolytic degradation by the polymerase used. Moreover, the complement of one of the stem sequences of the molecular beacon was included in the RCA products to avoid fluorescence quenching due to inter-molecular hybridization of neighboring molecular beacons hybridizing to the concatemeric polymerization product. The method allows highly accurate quantification of circularized DNA over a broad concentration range by relating the signal from the test DNA circle to an internal reference DNA circle reporting in a distinct fluorescence color.

  5. Using molecular beacons as a sensitive fluorescence assay for enzymatic cleavage of single-stranded DNA.

    PubMed

    Li, J J; Geyer, R; Tan, W

    2000-06-01

    Traditional methods to assay enzymatic cleavage of DNA are discontinuous and time consuming. In contrast, recently developed fluorescence methods are continuous and convenient. However, no fluorescence method has been developed for single-stranded DNA digestion. Here we introduce a novel method, based on molecular beacons, to assay single-stranded DNA cleavage by single strand-specific nucleases. A molecular beacon, a hairpin-shaped DNA probe labeled with a fluorophore and a quencher, is used as the substrate and enzymatic cleavage leads to fluorescence enhancement in the molecular beacon. This method permits real time detection of DNA cleavage and makes it easy to characterize the activity of DNA nucleases and to study the steady-state cleavage reaction kinetics. The excellent sensitivity, reproducibility and convenience will enable molecular beacons to be widely useful for the study of single-stranded DNA cleaving reactions.

  6. A molecular beacon, bead-based assay for the detection of nucleic acids by flow cytometry.

    PubMed

    Horejsh, Douglas; Martini, Federico; Poccia, Fabrizio; Ippolito, Giuseppe; Di Caro, Antonino; Capobianchi, Maria R

    2005-01-01

    Molecular beacons are dual-labelled probes that are typically used in real-time PCR assays, but have also been conjugated with solid matrices for use in microarrays or biosensors. We have developed a fluid array system using microsphere-conjugated molecular beacons and the flow cytometer for the specific, multiplexed detection of unlabelled nucleic acids in solution. For this array system, molecular beacons were conjugated with microspheres using a biotin-streptavidin linkage. A bridged conjugation method using streptavidin increased the signal-to-noise ratio, allowing for further discrimination of target quantitation. Using beads of different sizes and molecular beacons in two fluorophore colours, synthetic nucleic acid control sequences were specifically detected for three respiratory pathogens, including the SARS coronavirus in proof-of-concept experiments. Considering that routine flow cytometers are able to detect up to four fluorescent channels, this novel assay may allow for the specific multiplex detection of a nucleic acid panel in a single tube.

  7. A graphene oxide (GO)-based molecular beacon for DNA-binding transcription factor detection.

    PubMed

    Liu, Jing-Jing; Song, Xiao-Rong; Wang, Yi-Wei; Chen, Guo-Nan; Yang, Huang-Hao

    2012-06-21

    A GO-based molecular beacon assay was developed for rapid, sensitive and cost-efficient detection of transcription factor proteins. Furthermore, this assay can be employed for screening inhibitors of transcription factor proteins.

  8. Biomolecular computation with molecular beacons for quantitative analysis of target nucleic acids.

    PubMed

    Lim, Hee-Woong; Lee, Seung Hwan; Yang, Kyung-Ae; Yoo, Suk-In; Park, Tai Hyun; Zhang, Byoung-Tak

    2013-01-01

    Molecular beacons are efficient and useful tools for quantitative detection of specific target nucleic acids. Thanks to their simple protocol, molecular beacons have great potential as substrates for biomolecular computing. Here we present a molecular beacon-based biomolecular computing method for quantitative detection and analysis of target nucleic acids. Whereas the conventional quantitative assays using fluorescent dyes have been designed for single target detection or multiplexed detection, the proposed method enables us not only to detect multiple targets but also to compute their quantitative information by weighted-sum of the targets. The detection and computation are performed on a molecular level simultaneously, and the outputs are detected as fluorescence signals. Experimental results show the feasibility and effectiveness of our weighted detection and linear combination method using molecular beacons. Our method can serve as a primitive operation of molecular pattern analysis, and we demonstrate successful binary classifications of molecular patterns made of synthetic oligonucleotide DNA molecules.

  9. Design of an ultimate quencher free molecular beacon containing pyrrolocytidine-guanine base pair.

    PubMed

    Saito, Yoshio; Shinohara, Yuta; Bag, Subhendu Sekhar; Takeuchi, Yoshiki; Matsumoto, Katsuhiko; Saito, Isao

    2008-01-01

    A novel quencher free molecular beacon was designed in which fluorophore-labelled pyrrolocytidine was placed away from the stem terminal. This new type of MB was used for the detection of a target DNA with an excellent efficiency.

  10. An early status report on the Beacon Communities' plans for transformation via health information technology.

    PubMed

    McKethan, Aaron; Brammer, Craig; Fatemi, Parastou; Kim, Minyoung; Kirtane, Janhavi; Kunzman, Jason; Rao, Shaline; Jain, Sachin H

    2011-04-01

    The Beacon Community Program is part of a federal strategy for using health information technology as a foundation to improve the nation's health care system. In particular, Beacon Communities seek to increase the quality and efficiency of health care, improve the health of individuals and communities, and inform similar initiatives in other parts of the country. Each Beacon Community has set quality, efficiency, and health-related goals, and each is deploying multiple technology-enabled interventions to achieve them. Yet achieving large-scale and sustainable health care improvement also requires an implementation framework that can foster innovation and continuous learning from results. Based on the early experiences of the seventeen diverse Beacon Communities, this paper describes program design features that characterize how these initiatives are organized.

  11. Rapid DNA hybridization analysis using a PDMS microfluidic sensor and a molecular beacon.

    PubMed

    Kim, Sungyong; Chen, Lingxin; Lee, Sangyeop; Seong, Gi Hun; Choo, Jaebum; Lee, Eun Kyu; Oh, Chil-Hwan; Lee, Sanghoon

    2007-04-01

    A rapid DNA analysis has been developed based on a fluorescence intensity change of a molecular beacon in a PDMS microfluidic channel. Recently, we reported a new analytical method of DNA hybridization involving a PDMS microfluidic sensor using fluorescence energy transfer (FRET). However, there are some limitations in its application to real DNA samples because the target DNA must be labelled with a suitable fluorescent dye. To resolve this problem, we have developed a new DNA microfluidic sensor using a molecular beacon. By monitoring the change in the restored fluorescence intensity along the channel length, it is possible to rapidly detect any hybridization of the molecular beacon to the target DNA. In this case, the target DNA does not need to be labelled. Our experimental results demonstrate that this microfluidic sensor using a molecular beacon is a promising diagnostic tool for rapid DNA hybridization analysis.

  12. A room-temperature adenosine-based molecular beacon for highly sensitive detection of nucleic acids.

    PubMed

    Lin, Yen-Hsiu; Tseng, Wei-Lung

    2012-06-25

    This study developed a simple, sensitive, and selective molecular beacon for detecting nucleic acids at room temperature based on coralyne induced conformational change of a MB through A(2)-coralyne-A(2) coordination.

  13. Theory of continuous-wave excitation of the sodium beacon

    SciTech Connect

    Milonni, P.W.; Fearn, H.; Telle, J.M.; Fugate, R.Q.

    1999-10-01

    We extend our previous analysis of the sodium beacon [J. Opt. Soc. Am. A {bold 15}, 217 (1998)] to the case of continuous-wave excitation. Various effects that could be ignored in the case of pulsed excitation, such as the geomagnetic field, the recoil of the sodium atoms upon absorption and emission, and collisions of the sodium atoms with other mesospheric species, are included. Spin-relaxation collisions are among the most important of these effects for the cases considered. Analytical approximations to numerical results are presented, and using a semi-empirical estimate for Na-O{sub 2} spin relaxation, we compute photon returns in good agreement with recently reported measurements at the Steward Observatory. {copyright} 1999 Optical Society of America

  14. An OR logic gate based on two molecular beacons.

    PubMed

    Guo, Jing; Yang, Renqiang

    2012-03-01

    Design of elementary molecular logic gates is the key and the fundamental of performing complicated Boolean calculations. Herein, we report a strategy for constructing a DNA-based OR gate by using the mechanism of sequence recognition and the principle of fluorescence resonance energy transfer (FRET). In this system, the gate is entirely composed of a single strand of DNA (A, B and C) and the inputs are the molecular beacon probes (MB1 and MB2). Changes in fluorescence intensity confirm the realization of the OR logic operation and electrophoresis experiments verify these results. Our successful application of DNA to perform the binary operation represents that DNA can serve as an efficient biomaterial for designing molecular logic gates and devices.

  15. Cholesterol-linked fluorescent molecular beacons with enhanced cell permeability.

    PubMed

    Seo, Young Jun; Jeong, Hyun Seok; Bang, Eun-Kyoung; Hwang, Gil Tae; Jung, Jong Ha; Jang, Sung Key; Kim, Byeang Hyean

    2006-01-01

    We appended pyrene units covalently onto adenosine (forming A(P) units) and then incorporated them into oligonucleotides such that they were positioned in complementary locations in opposite strands in the middle positions of hairpin stems. System 1 (A(P)A(P)) behaves as an effective molecular beacon (MB) that changes color from green to blue upon duplex formation. In addition, we attached a cholesterol unit to a free terminus of one of these hairpins; this approach enhanced the cellular delivery of the modified MB relative to those encountered when using conventional transfection methods. These structurally simple cholesterol-based MB systems, which can be synthesized very efficiently, have good potential for opening up new and exciting opportunities in the field of in vivo biosensors.

  16. Single-strand stacking free energy from DNA beacon kinetics.

    PubMed

    Aalberts, Daniel P; Parman, John M; Goddard, Noel L

    2003-05-01

    DNA beacons are short single-stranded chains which can form closed hairpin shapes through complementary base pairing at their ends. Contrary to the common polymer theory assumption that only their loop length matters, experiments show that their closing kinetics depend on the loop composition. We have modeled the closing kinetics and in so doing have obtained stacking enthalpies and entropies for single-stranded nucleic acids. The resulting change of persistence length with temperature effects the dynamics. With a Monte Carlo study, we answer another polymer question of how the closing time scales with chain length, finding tau approximately N(2.44+/-0.02). There is a significant crossover for shorter chains, bringing the effective exponent into good agreement with experiment.

  17. Enzymatic amplification detection of DNA based on "molecular beacon" biosensors.

    PubMed

    Mao, Xun; Jiang, Jianhui; Xu, Xiangmin; Chu, Xia; Luo, Yan; Shen, Guoli; Yu, Ruqin

    2008-05-15

    We described a novel electrochemical DNA biosensor based on molecular beacon (MB) probe and enzymatic amplification protocol. The MB modified with a thiol at its 5' end and a biotin at its 3' end was immobilized on the gold electrode through mixed self-assembly process. Hybridization events between MB and target DNA cause the conformational change of the MB, triggering the attached biotin group on the electrode surface. Following the specific interaction between the conformation-triggered biotin and streptavidin-horseradish peroxidase (HRP), subsequent quantification of DNA was realized by electrochemical detection of enzymatic product in the presence of substrate. The detection limit is obtained as low as 0.1nM. The presented DNA biosensor has good selectivity, being able to differentiate between a complementary target DNA sequence and one containing G-G single-base mismatches.

  18. "A beacon of light". Spirituality in the heart transplant patient.

    PubMed

    Walton, J; St Clair, K

    2000-03-01

    For the cardiac transplant recipients in this study, spirituality was like a beacon of light, providing illumination and sustaining hope while enduring illness. Spirituality was nurtured by Developing Faith and by the Presence of significant others, health care providers, and the Divine to sustain hope. Spirituality throughout the transplantation process was described by concepts of faith, presence, enduring illness, and sustaining hope. The four dynamic phases of Enduring Illness can assist health care providers in understanding what spirituality means to transplant patients. This conceptual model of spirituality demonstrates the important role that spirituality plays in recovery. Clinical application of this model will allow health care providers involved in the care of cardiac transplant patients to integrate spirituality into their patients' plan of care. With future research, this model can be easily modified and built upon to meet the needs of cardiac transplant patients in all phases of transplantation.

  19. Low profile optical system for an aircraft beacon.

    PubMed

    Schwartz, A H

    1971-02-01

    An optical system producing an annular cone of radiation from a point source using a low profile front lens is shown to have application as a beacon for high speed vehicles. The system comprises a high pressure short are light source with axial electrodes and integral collector, a conical reflector, and a divergent meniscus lens that has low protrusion over the surface of the vehicle. The system has minimal drag, and the radiation is distributed in directions close to the plane perpendicular to the optical axis. The influences of various parameters such as lens camber, lens aperture, source size, collector shape, collection efficiency, and beam divergence are discussed. A prototype was built at Eimae Division of Varian using a xenon short arc lamp with metal ceramic structure and integral collector.

  20. Monitoring molecular beacon/DNA interactions using atomic force microscopy.

    PubMed

    Jin, Yan; Wang, Kemin; Tan, Weihong; Wu, Ping; Wang, Qing; Huang, Hongmei; Huang, Shasheng; Tang, Zhiwen; Guo, Qiuping

    2004-10-01

    The molecular beacon (MB) is a new fluorescence probe containing a single-stranded oligonucleotide with a probe sequence embedded in complementary sequences that form a hairpin stem. Due to the inherent fluorescent signal transduction mechanism, an MB functions as a sensitive probe with a high signal-to-background ratio for real-time monitoring and provides a variety of exciting opportunities in DNA, RNA, and protein studies. To better understand the properties of MBs, the specific interactions between MB and target DNA (complementary and one-base mismatch) have been directly investigated by atomic force microscopy. The interaction force between a linear DNA probe and the target DNA was also detected and compared to that between MB and target DNA. The results demonstrate the high specificity of the MB/target DNA compared to the linear DNA/target DNA interaction.

  1. Ultrasensitive DNAzyme beacon for lanthanides and metal speciation.

    PubMed

    Huang, Po-Jung Jimmy; Lin, Jenny; Cao, Jing; Vazin, Mahsa; Liu, Juewen

    2014-02-01

    Metal-ion detection and speciation analysis is crucial for environmental monitoring. Despite the importance of lanthanides, few sensors are available for their detection. DNAzymes have been previously used to detect divalent metals, while no analytical work was carried out for trivalent and tetravalent ions. Herein, in vitro selection was performed using a Ce(4+) salt as the target metal, and a new DNAzyme (named Ce13) with a bulged hairpin structure was isolated and characterized. Interestingly, Ce13 has almost no activity with Ce(4+) but is highly active with all trivalent lanthanides and Y(3+), serving as a general probe for rare earth metals (omitting Sc). A DNAzyme beacon was engineered detecting down to 1.7 nM Ce(3+) (240 parts per trillion), and other lanthanides showed similar sensitivity. The feasibility of metal speciation analysis was demonstrated by measuring the reduction of Ce(4+) to Ce(3+).

  2. Recent trends in molecular beacon design and applications.

    PubMed

    Huang, Kewei; Martí, Angel A

    2012-04-01

    A molecular beacon (MB) is a hairpin-structured oligonucleotide probe containing a photoluminescent species (PLS) and a quencher at different ends of the strand. In a recognition and detection process, the hybridization of MBs with target DNA sequences restores the strong photoluminescence, which is quenched before hybridization. Making better MBs involves reducing the background photoluminescence and increasing the brightness of the PLS, which therefore involves the development of new PLS and quenchers, as well as innovative PLS-quencher systems. Heavy-metal complexes, nanocrystals, pyrene compounds, and other materials with excellent photophysical properties have been applied as PLS of MBs. Nanoparticles, nanowires, graphene, metal films, and many other media have also been introduced to quench photoluminescence. On the basis of their high specificity, selectivity, and sensitivity, MBs are developed as a general platform for sensing, producing, and carrying molecules other than oligonucleotides.

  3. Electrochemical proteolytic beacon for detection of matrix metalloproteinase activities.

    PubMed

    Liu, Guodong; Wang, Jun; Wunschel, David S; Lin, Yuehe

    2006-09-27

    This communication describes a novel method for detecting matrix metalloproteinase-7 activity using a peptide substrate labeled with a ferrocene reporter. The substrate serves as a selective "electrochemical proteolytic beacon" (EPB) for this metalloproteinase. The EPB is immobilized on a gold electrode surface to enable "on-off" electrochemical signaling capability for uncleaved and cleaved events. The EPB is efficiently and selectively cleaved by MMP-7 as measured by the rate of decrease in redox current of ferrocene. Direct transduction of a signal corresponding to peptide cleavage events into an electronic signal thus provides a simple, sensitive route for detecting the MMP activity. The new method allows for identification of the activity of MMP-7 in concentrations as low as 3.4 pM. The concept can be extended to design a multiple peptide substrate labeled with different electroactive reporters for assaying multiple MMPs activities.

  4. The American Association of Critical Care Nurse's Beacon Award: a framework for quality.

    PubMed

    Reed, Kevin D

    2008-12-01

    The Beacon Award for Critical Care Excellence recognizes individual critical care units that have met rigid criteria for excellence, exhibiting high-quality standards and exceptional care of patients and their families. Used as a framework for quality, the award criteria focus on structure, process, and outcomes that enable quality to emerge in the critical care environment. The journey toward meeting Beacon Award criteria can produce long-lasting changes that transform unit-based culture and lead to sustained excellence.

  5. A molecular beacon-based method for screening cervical cancer.

    PubMed

    Han, Suxia; Li, Ling; Jia, Xi; Ou, Wei; Ma, Jinlu; Wang, Hao; Zhao, Jing; Zhu, Qing

    2012-11-01

    The aim of this study is to develop a new screening method, molecular beacon (MB) imaging, for detection of cervical cancer and to determine its potential clinical applications by examining the sensitivity and specificity of target-specific MBs. Two target-specific molecular beacons were designed and synthesized for survivin and HPV16E6 mRNA. The two designed MBs and a random control MB were used to detect cervical cancer cell lines and a normal cell line. RT-PCR and western blot targeting survivin and HPV16E6 was done for verification. Furthermore the sensitivity and the specificity of the survivin and HPV16E6 mRNA MBs were examined in smears from 125 clinical cervical patients. The survivin and HPV16E6 mRNA MBs generated a strong fluorescence signal in cervical cancer cell lines, but not in the normal cell line, while the random control MB did not generated any signal in both cell lines. The fluorescence intensity correlated well with the gene expression levels in the cells determined by reverse transcription-PCR and Western blot analysis. The clinical sensitivity and the specificity of survivin MB-FITC were 72.5 and 77% while those of HPV16E6 MB-Cy3 were 96.1% and 71.6%, respectively. A parallel test of the two target MBs showed that the sensitivity increased to 98% and the specificity was 70.2%. The survivin and HPV16E6 mRNA MBs showed good reliability and sensitivity. They have great potential for clinical use in cervical cancer screening.

  6. Visual detection of multidrug resistance gene in living cell using the molecular beacon imaging

    NASA Astrophysics Data System (ADS)

    Zhou, Qiumei; Ma, Yi; Gu, Yueqing

    2014-09-01

    A major problem in cancer treatment is the development of resistance to chemotherapeutic agents in tumor cells. Detection of effective prognostic biomarkers and targets are of crucial importance to the management of individualized therapies. However, quantitative analysis of the drug resistance gene had been difficult because of technical limitations. In this study, we designed and used a special hairpin deoxyribonucleic acid (DNA), which served as a beacon for detecting human drug resistance indicater. Upon hybridizing with the target mRNA, the hairpin DNA modified gold nanoparticle beacons (hDAuNP beacons) release the fluorophores attached at 5'end of the oligonucleotide sequence. The fluorescence properties of the beacon before and after the hybridization with the complementary DNA were confirmed in vitro. The hDAuNP beacons could be taken up by living cells with low inherent cytotoxicity and higher stability. hDAuNP beacon imaged by confocal laser scanning microscopy to detect the resistance gene expression. The detected fluorescence in MCF7and MCF7/ADR cells correlates with the specific drug resistance gene expression, which is consistent with the result from Q-PCR. Thus, this approach overcame many of the challenges of previous techniques by creating highly sensitive and effective intracellular probes for monitoring gene expression.

  7. Marking emergency exits and evacuation routes with sound beacons utilizing the precedence effect

    NASA Astrophysics Data System (ADS)

    van Wijngaarden, Sander J.; Bronkhorst, Adelbert W.; Boer, Louis C.

    2001-05-01

    Sound beacons can be extremely useful during emergency evacuations, especially when vision is obscured by smoke. When exits are marked with suitable sound sources, people can find these using only their capacity for directional hearing. Unfortunately, unless very explicit instructions were given, sound beacons currently commercially available (based on modulated noise) led to disappointing results during an evacuation experiment in a traffic tunnel. Only 19% out of 65 subjects were able to find an exit by ear. A signal designed to be more self-explanatory and less hostile-sounding (alternating chime signal and spoken message ``exit here'') increased the success rate to 86%. In a more complex environment-a mock-up of a ship's interior-routes to the exit were marked using multiple beacons. By applying carefully designed time delays between successive beacons, the direction of the route was marked, utilizing the precedence effect. Out of 34 subjects, 71% correctly followed the evacuation route by ear (compared to 24% for a noise signal as used in commercially available beacons). Even when subjects were forced to make a worst-case left-right decision at a T-junction, between two beacons differing only in arrival of the first wave front, 77% made the right decision.

  8. An Adaptive Scheme for Robot Localization and Mapping with Dynamically Configurable Inter-Beacon Range Measurements

    PubMed Central

    Torres-González, Arturo; Martinez-de Dios, Jose Ramiro; Ollero, Anibal

    2014-01-01

    This work is motivated by robot-sensor network cooperation techniques where sensor nodes (beacons) are used as landmarks for range-only (RO) simultaneous localization and mapping (SLAM). This paper presents a RO-SLAM scheme that actuates over the measurement gathering process using mechanisms that dynamically modify the rate and variety of measurements that are integrated in the SLAM filter. It includes a measurement gathering module that can be configured to collect direct robot-beacon and inter-beacon measurements with different inter-beacon depth levels and at different rates. It also includes a supervision module that monitors the SLAM performance and dynamically selects the measurement gathering configuration balancing SLAM accuracy and resource consumption. The proposed scheme has been applied to an extended Kalman filter SLAM with auxiliary particle filters for beacon initialization (PF-EKF SLAM) and validated with experiments performed in the CONET Integrated Testbed. It achieved lower map and robot errors (34% and 14%, respectively) than traditional methods with a lower computational burden (16%) and similar beacon energy consumption. PMID:24776938

  9. An adaptive scheme for robot localization and mapping with dynamically configurable inter-beacon range measurements.

    PubMed

    Torres-González, Arturo; Martinez-de Dios, Jose Ramiro; Ollero, Anibal

    2014-04-25

    This work is motivated by robot-sensor network cooperation techniques where sensor nodes (beacons) are used as landmarks for range-only (RO) simultaneous localization and mapping (SLAM). This paper presents a RO-SLAM scheme that actuates over the measurement gathering process using mechanisms that dynamically modify the rate and variety of measurements that are integrated in the SLAM filter. It includes a measurement gathering module that can be configured to collect direct robot-beacon and inter-beacon measurements with different inter-beacon depth levels and at different rates. It also includes a supervision module that monitors the SLAM performance and dynamically selects the measurement gathering configuration balancing SLAM accuracy and resource consumption. The proposed scheme has been applied to an extended Kalman filter SLAM with auxiliary particle filters for beacon initialization (PF-EKF SLAM) and validated with experiments performed in the CONET Integrated Testbed. It achieved lower map and robot errors (34% and 14%, respectively) than traditional methods with a lower computational burden (16%) and similar beacon energy consumption.

  10. Serum inverts and improves the fluorescence response of an aptamer beacon to various vitamin D analytes.

    PubMed

    Bruno, John G; Carrillo, Maria P; Phillips, Taylor; Edge, Allison

    2012-01-01

    A dominant aptamer loop structure from a library of nearly 100 candidate aptamer sequences developed against immobilized 25-hydroxyvitamin D(3) (calcidiol) was converted into a 5'-TYE 665 and 3'-Iowa black-labelled aptamer beacon. The aptamer beacon exhibited a mild 'lights on' reaction in buffer as a function of increasing concentrations of several vitamin D analogues and metabolites, with a limit of detection of approximately 200 ng/mL, and was not specific for any particular congener. In 10% or 50% human serum, the same aptamer beacon inverted its fluorescence behaviour to become a more intense 'lights off' reaction with an improved limit of detection in the range 4-16 ng/mL. We hypothesized that this drastic change in fluorescence behaviour was due to the presence of creatinine and urea in serum, which might destabilize the quenched beacon, causing an increase in fluorescence followed by decreasing fluorescence as a function of vitamin D concentrations that may bind and quench increasingly greater fractions of the denatured beacons. However, the results of several control experiments in the presence of physiological or greater concentrations of creatinine and urea, alone or combined in buffer, failed to produce the beacon fluorescence inversion. Other possible mechanistic hypotheses are also discussed.

  11. An adaptive scheme for robot localization and mapping with dynamically configurable inter-beacon range measurements.

    PubMed

    Torres-González, Arturo; Martinez-de Dios, Jose Ramiro; Ollero, Anibal

    2014-01-01

    This work is motivated by robot-sensor network cooperation techniques where sensor nodes (beacons) are used as landmarks for range-only (RO) simultaneous localization and mapping (SLAM). This paper presents a RO-SLAM scheme that actuates over the measurement gathering process using mechanisms that dynamically modify the rate and variety of measurements that are integrated in the SLAM filter. It includes a measurement gathering module that can be configured to collect direct robot-beacon and inter-beacon measurements with different inter-beacon depth levels and at different rates. It also includes a supervision module that monitors the SLAM performance and dynamically selects the measurement gathering configuration balancing SLAM accuracy and resource consumption. The proposed scheme has been applied to an extended Kalman filter SLAM with auxiliary particle filters for beacon initialization (PF-EKF SLAM) and validated with experiments performed in the CONET Integrated Testbed. It achieved lower map and robot errors (34% and 14%, respectively) than traditional methods with a lower computational burden (16%) and similar beacon energy consumption. PMID:24776938

  12. Catalytic and molecular beacons for amplified detection of metal ions and organic molecules with high sensitivity.

    PubMed

    Zhang, Xiao-Bing; Wang, Zidong; Xing, Hang; Xiang, Yu; Lu, Yi

    2010-06-15

    The catalytic beacon has emerged as a general platform for sensing metal ions and organic molecules. However, few reports have taken advantage of the true potential of catalytic beacons in signal amplification through multiple enzymatic turnovers, as existing designs require either equal concentrations of substrate and DNAzyme or an excess of DNAzyme in order to maintain efficient quenching, eliminating the excess of substrate necessary for multiple turnovers. On the basis of the large difference in the melting temperatures between the intramolecular molecular beacon stem and intermolecular products of identical sequences, we here report a general strategy of catalytic and molecular beacon (CAMB) that combines the advantages of the molecular beacon for highly efficient quenching with the catalytic beacon for amplified sensing through enzymatic turnovers. Such a CAMB design allows detection of metal ions such as Pb(2+) with a high sensitivity (LOD = 600 pM). Furthermore, the aptamer sequence has been introduced into DNAzyme to use the modified CAMB for amplified sensing of adenosine with similar high sensitivity. These results together demonstrate that CAMB provides a general platform for amplified detection of a wide range of targets.

  13. Evaluation of microfluidic biosensor development using microscopic analysis of molecular beacon hybridization kinetics.

    PubMed

    Xi, Chuanwu; Raskin, Lutgarde; Boppart, Stephen A

    2005-03-01

    Molecular beacons, oligonucleotide probes that fluoresce upon hybridization to a target nucleic acid, can be used in microfluidic devices to detect and quantify nucleic acids in solution as well as inside bacterial cells. Three essential steps towards the development of such devices as integrated microfluidic biosensors using molecular beacons were investigated in the present study. First, experiments using real-time confocal microscopy indicated that diffusion of DNA molecular beacons across a 100-mum diameter microfluidic channel took less than one minute after the flow of reagents was stopped. Second, experiments to evaluate hybridization kinetics of DNA molecular beacons with target nucleic acids in solution showed that DNA molecular beacons can be used to characterize hybridization kinetics in real time in microfluidic channels and that hybridization signals approached their maximum in approximately three minutes. Finally, it was demonstrated that peptide nucleic acid molecular beacons can be used to detect bacterial cells in microfluidic devices. These results suggest that the use of microfluidic devices to detect nucleic acids in solution and in bacterial cells is promising and that further development of an integrated microfluidic biosensor for bacterial detection based on this concept is warranted.

  14. Polyacrylamide gel film immobilized molecular beacon array for single nucleotide mismatch detection.

    PubMed

    Wang, Yijin; Wang, Hong; Gao, Lu; Liu, Heping; Lu, Zuhong; He, Nongyue

    2005-04-01

    We reported polyacrylamide gel immobilized molecular beacon array for single nucleotide mismatch detection in this paper. Molecular beacons are oligonucleotide probes fluorescing upon hybridization to their complementary DNA/RNA targets with excellent sensitivity and high selectivity. The specially designed molecular beacon for immobilization contains a 15 base loop sequence with a 5 base pair stem, a polyT (20 bases) spacer, a 5'-end amino group for immobilization, a fluorescein in the middle of the sequence as the fluorophore, and a 3'-end DABCYL as the quencher. Between the 5'-end amino group and the stem, the polyT is used to minimize disability caused by 5'-end immobilization. The molecular beacon microarray was fabricated by a pin-based spotting robot and the hybridization was investigated by confocal microscope. A real-time hybridization process at room temperature was registered every minute for 20 min after the target solution was pumped into the hybridization cell. The result indicates that a polyacrylamide film coated glass slide provides an ideal solution-like environment for molecular beacon probes. The potential applications of this kind of molecular beacon array are mutation detection, disease mechanisms, disease diagnostics, etc. in a parallel, cost saving, and label-free detection way.

  15. Beacon training in a water maze can facilitate and compete with subsequent room cue learning in rats.

    PubMed

    Timberlake, William; Sinning, Susan A; Leffel, Joseph K

    2007-07-01

    In Stage 1 of 4 experiments in which rats completed a water-maze blocking procedure, experimental groups were trained to use a predictive beacon (hanging above, connected to, or displaced from the platform) to find a submerged escape platform in the presence of predictive or irrelevant background cues and in the presence or absence of irrelevant landmarks. In Stage 2, a fixed beacon, landmarks, and background cues all predicted the platform location. A Room Test (landmarks and background cues only) showed that Stage 1 training with a fixed hanging beacon or the moving displaced beacon facilitated Stage 2 learning of predictive room cues for experimental relative to control subjects. In contrast, Stage 1 training with a moving pole beacon interfered with Stage 2 learning about predictive room cues relative to controls, whereas training with a fixed pole or moving hanging beacon had no effect. We conclude that multiple spatial learning processes influence locating an escape platform in the water maze.

  16. Superfund Record of Decision (EPA Region 1): Beacon Heights Landfill site, Beacon Falls, CT. (First remedial action), September 1990. (Supplemental). Final report

    SciTech Connect

    Not Available

    1990-09-28

    The 34-acre Beacon Heights Landfill site is on the northwest corner of an 82-acre property in Beacon Falls, Connecticut. The ROD supplements the 1985 ROD by resolving those determinations left open in the 1985 ROD, including the manner and locations of leachate treatment/disposal; cleanup levels for soil deemed impracticable to cap in areas contiguous to the landfill; and the need for air pollution controls on the landfill gas vents. The primary contaminants of concern affecting the soil, ground water, surface water, and air are VOCs, including benzene, toluene, and xylene.

  17. Improving adaptive optical systems by the use of multiple laser beacon configurations

    NASA Astrophysics Data System (ADS)

    de La Rue, Imelda Atencio

    The field of adaptive optics (AO) and laser-beacon AO has been successfully implemented in the last part of the 20th century. Adaptive optics greatly improves the resolution capabilities of ground-based telescopes by correcting for atmospheric turbulence. The initial implementation of laser-beacon AO was done on relatively small telescopes, on the order of 1.5 m. However, with larger aperture telescopes being built, such as the 8-m class Gemini telescopes, there is much room for improvement. Errors resulting from laser-beacon AO, such as focus anisoplanatism, become worse with an increase in aperture diameter. Tilt anisoplanatism is also a problem, regardless of the size of telescope, and also needs to be reduced to enhance the resolution of the objects being observed. This dissertation investigates alternate laser-beacon AO configurations, to reduce the effects of focus and tilt anisoplanatism for larger aperture telescopes. The configurations investigated include single and multiple laser beacons at single altitudes and single and multiple laser beacons at multiple altitudes. These second configurations are referred to as hybrid beacon systems and consist of Rayleigh beacons at altitudes of 10 to 20˜km and sodium beacons at about 90˜km, the location of the sodium layer. Hybrid systems are shown to reduce both focus and tilt anisoplanatism as opposed to the first configurations which only aid in reducing focus anisoplanatism. An addition to the hybrid systems with multiple beacons, the use of multiple deformable mirrors (DM's) is investigated. These additional DM's are placed conjugate to atmospheric altitudes with predominant turbulence, beyond the traditional conjugate location of the primary mirror. They correct for turbulence at these atmospheric layers and are referred to as multi-conjugate adaptive optical (MCAO) systems. The purpose of MCAO configurations is to increase the corrected field of view. For the types of systems investigated in this

  18. Quantum dot-based molecular beacon to monitor intracellular microRNAs.

    PubMed

    Lee, Jonghwan; Moon, Sung Ung; Lee, Yong Seung; Ali, Bahy A; Al-Khedhairy, Abdulaziz A; Ali, Daoud; Ahmed, Javed; Al Salem, Abdullah M; Kim, Soonhag

    2015-06-02

    Fluorescence monitoring of endogenous microRNA (miRNA or miR) activity related to neuronal development using nano-sized materials provides crucial information on miRNA expression patterns in a noninvasive manner. In this study, we report a new method to monitor intracellular miRNA124a using quantum dot-based molecular beacon (R9-QD-miR124a beacon). The R9-QD-miR124a beacon was constructed using QDs and two probes, miR124a-targeting oligomer and arginine rich cell-penetrating peptide (R9 peptide). The miR124a-targeting oligomer contains a miR124a binging sequence and a black hole quencher 1 (BHQ1). In the absence of target miR124a, the R9-QD-miR124a beacon forms a partial duplex beacon and remained in quenched state because the BHQ1 quenches the fluorescence signal of the R9-QD-miR124a beacon. The binding of miR124a to the miR124a binding sequence of the miR124a-targeting oligomer triggered the separation of the BHQ1 quencher and subsequent signal-on of a red fluorescence signal. Moreover, enhanced cellular uptake was achieved by conjugation with the R9 peptide, which resulted in increased fluorescent signal of the R9-QD-miR124a beacons in P19 cells during neurogenesis due to the endogenous expression of miR124a.

  19. Analytical performance of molecular beacons on surface immobilized gold nanoparticles of varying size and density.

    PubMed

    Uddayasankar, Uvaraj; Krull, Ulrich J

    2013-11-25

    The high quenching efficiency of metal nanoparticles has facilitated its use as quenchers in molecular beacons. To optimize this system, a good understanding of the many factors that influence molecular beacon performance is required. In this study, molecular beacon performance was evaluated as a function of gold nanoparticle size and its immobilization characteristics. Gold nanoparticles of 4 nm, 15 nm and 87 nm diameter, were immobilized onto glass slides. Each size regime offered distinctive optical properties for fluorescence quenching of molecular dyes that were conjugated to oligonucleotides that were immobilized to the gold nanoparticles. Rigid double stranded DNA was used as a model to place fluorophores at different distances from the gold nanoparticles. The effect of particle size and also the immobilization density of nanoparticles was evaluated. The 4 nm and 87 nm gold nanoparticles offered the highest sensitivity in terms of the change in fluorescence intensity as a function of distance (3-fold improvement for Cy5). The optical properties of the molecular fluorophore was of significance, with Cy5 offering higher contrast ratios than Cy3 due to the red-shifted emission spectrum relative to the plasmon peak. A high density of gold nanoparticles reduced contrast ratios, indicating preference for a monolayer of immobilized nanoparticles when considering analytical performance. Molecular beacon probes were then used in place of the double stranded oligonucleotides. There was a strong dependence of molecular beacon performance on the length of a linker used for attachment to the nanoparticle surface. The optimal optical performance was obtained with 4 nm gold nanoparticles that were immobilized as monolayers of low density (5.7×10(11)particles cm(-2)) on glass surfaces. These nanoparticle surfaces offered a 2-fold improvement in analytical performance of the molecular beacons when compared to other nanoparticle sizes investigated. The principles developed

  20. Semiautomated clone verification by real-time PCR using molecular beacons.

    PubMed

    van Schie, R C; Marras, S A; Conroy, J M; Nowak, N J; Catanese, J J; de Jong, P J

    2000-12-01

    Conventional, high-throughput PCR analysis of common elements utilizing numerous primer sets and template DNA requires multiple rounds of PCR to ensure optimal conditions. Laborious gel electrophoresis and staining is then necessary to visualize amplification products. We propose novel multicolor molecular beacons, to establish a high-throughput, PCR-based sequence tagged site (STS) detection system that swiftly and accurately confirms marker content in template containing common repeat elements. A simple, one-tube, real-time PCR assay system was developed to specifically detect regions containing CA and GATA repeats. Ninety-six samples can be confirmed for marker content in a closed-tube format in 3 h, eliminating product confirmation on agarose gels and avoiding crossover contamination. Multiple STSs can be detected simultaneously in the same reaction tube by utilizing molecular beacons labeled with multicolor fluorophores. Template DNA from 260 RPCI-11 bacterial artificial chromosome (BAC) clones was examined for the presence of CA and/or GATA repeats using molecular beacon PCR and compared with conventional PCR results of the same clones. Of the 205 clones containing CA and GATA repeats, we were able to identify 129 clones (CA, n = 99; GATA, n = 30) by using molecular beacons and only 121 clones (CA, n = 92; GATA, n = 29) by conventional PCR amplification. As anticipated, 55 clones that contained sequences other than CA or GATA failed molecular beacon detection. Molecular beacon PCR, employing beacons specific for tandem repeat elements, provides a fast, accurate, and sensitive multiplex detection assay that will expedite verification of marker content in a multitude of template containing these repeats.

  1. Beacon/ubiquitin-like 5-immunoreactivity in the hypothalamus and pituitary of the mouse.

    PubMed

    Brailoiu, G Cristina; Dun, Siok L; Chi, Michelle; Ohsawa, Masahiro; Chang, Jaw Kang; Yang, Jun; Dun, Nae J

    2003-09-12

    Beacon is a 73-amino acid peptide encoded by a novel gene in the hypothalamus of Israeli sand rat Psammomys obesus. Reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemical techniques were used to investigate the presence of beacon mRNA and the distribution of beacon-immunoreactivity (irBC) in the hypothalamus of ICR mice. RT-PCR experiments revealed beacon mRNA in the mouse hypothalamus. Using a rabbit polyclonal antiserum directed against the synthetic C-terminal peptide fragment (47-73), irBC was detected in the mouse hypothalamus and pituitary. In the hypothalamus, irBC was concentrated in perikarya of the supraoptic (SO), paraventricular (PVH) and accessory neurosecretory nuclei and in cell processes of the median eminence and pituitary stalk. In the pituitary, irBC was noted mainly in the posterior lobe. Double-labeling the hypothalamic sections with guinea-pig vasopressin-antiserum or mouse monoclonal oxytocin-antibody and beacon-antiserum revealed that <30% of vasopressin-immunoreactive neurons and nearly all oxytocin-immunoreactive neurons in the PVH and SO were irBC. The result shows the presence of beacon mRNA in the mouse hypothalamus, and the distribution of irBC is distinctively different from that reported in the hypothalamus of Psammomys obesus, but similar to that of the Sprague-Dawley rats described in our earlier study. More interestingly, Blast search uncovered a 73-amino acid peptide, human ubiquitin-like 5, which has the same exact sequence as beacon. Thus, irBC observed in the mouse brain could be that of ubiquitin-like 5.

  2. Real-time quantitative nicking endonuclease-mediated isothermal amplification with small molecular beacons.

    PubMed

    Xu, Wentao; Wang, Chenguang; Zhu, Pengyu; Guo, Tianxiao; Xu, Yuancong; Huang, Kunlun; Luo, Yunbo

    2016-04-21

    Techniques of isothermal amplification have recently made great strides, and have generated significant interest in the field of point-of-care detection. Nicking endonuclease-mediated isothermal amplification (NEMA) is an example of simple isothermal technology. In this paper, a real-time quantitative nicking endonuclease-mediated isothermal amplification with small molecular beacons (SMB-NEMA) of improved specificity and sensitivity is described. First, we optimized the prohibition of de novo synthesis by choosing Nt·BstNBI endonuclease. Second, the whole genome was successfully amplified with Nt·BstNBI (6 U), betaine (1 M) and trehalose (60 mM) for the first time. Third, we achieved 10 pg sensitivity for the first time after adding a small molecular beacon that spontaneously undergoes a conformational change when hybridizing to target, and the practical test validated the assay's application. The small molecular beacon has a similar melting temperature to the reaction temperature, but is approximately 10 bp shorter than the length of a traditional molecular beacon. A new threshold regulation was also established for isothermal conditions. Finally, we established a thermodynamic model for designing small molecular beacons. This multistate model is more correct than the traditional algorithm. This theoretical and practical basis will help us to monitor SMB-NEMA in a quantitative way. In summary, our SMB-NEMA method allows the simple, specific and sensitive assessment of isothermal DNA quantification. PMID:27027375

  3. Using molecular beacons to detect single-nucleotide polymorphisms with real-time PCR.

    PubMed

    Mhlanga, M M; Malmberg, L

    2001-12-01

    Detection of single-nucleotide polymorphisms (SNPs) in high-throughput studies promises to be an expanding field of molecular medicine in the near future. Highly specific, simple, and accessible methods are needed to meet the rigorous requirements of single-nucleotide detection needed in pharmacogenomic studies, linkage analysis, and the detection of pathogens. Molecular beacons present such a solution for the high-throughput screening of SNPs in homogeneous assays using the polymerase chain reaction (PCR). Molecular beacons are probes that fluoresce on hybridization to their perfectly complementary targets. In recent years they have emerged as a leading genetic analysis tool in a wide range of contexts from quantification of RNA transcripts, to probes on microarrays, to single-nucleotide polymorphism detection. The majority of these methods use PCR to obtain sufficient amounts of sample to analyze. The use of molecular beacons with other amplification schemes has been reliably demonstrated, though PCR remains the method of choice. Here we discuss and present how to design and use molecular beacons to achieve reliable SNP genotyping and allele discrimination in real-time PCR. In addition, we provide a new means of analyzing data outputs from such real-time PCR assays that compensates for differences between sample condition, assay conditions, variations in fluorescent signal, and amplification efficiency. The mechanisms by which molecular beacons are able to have extraordinary specificity are also presented. PMID:11846616

  4. Quencher-free molecular beacon tethering 7-hydroxycoumarin detects targets through protonation/deprotonation.

    PubMed

    Kashida, Hiromu; Yamaguchi, Kyohei; Hara, Yuichi; Asanuma, Hiroyuki

    2012-07-15

    In this study, we synthesized a simple but efficient quencher-free molecular beacon tethering 7-hydroxycoumarin on D-threoninol based on its pK(a) change. The pK(a) of 7-hydroxycoumarin in a single strand was determined as 8.8, whereas that intercalated in the duplex was over 10. This large pK(a) shift (more than 1.2) upon hybridization could be attributed to the anionic and hydrophobic microenvironment inside the DNA duplex. Because 7-hydroxycoumarin quenches its fluorescence upon protonation, the emission intensity of the duplex at pH 8.5 was 1/15 that of the single strand. We applied this quenching mechanism to the preparation of a quencher-free molecular beacon by introducing the dye into the middle of the stem part. In the absence of the target, the stem region formed a duplex and fluorescence was quenched. However, when the target was added, the molecular beacon opened and the dye was deprotonated. As a result, the emission intensity of the molecular beacon with the target was 10 times higher than that without the target. Accordingly, a quencher-free molecular beacon utilizing the pK(a) change was successfully developed.

  5. Comparison of COMPARE and BEACON subcompartment analyses of Battelle-Frankfurt containment tests. [PWR

    SciTech Connect

    Idar, E.S.; Lime, J.F.; Gido, R.G.

    1983-01-01

    This report presents the results of computations performed with the COMPARE/MOD1 and BEACON/MOD3 computer codes for selected Battelle-Frankfurt loss-of-coolant accident experiments. COMPARE is used widely to perform nuclear power plant containment subcompartment analyses, and BEACON is an advanced multiphase, multidimensional best-estimate code. The objective of this study was to evaluate the margins of COMPARE calculations by comparing them with BEACON calculations and test data. The calculations were performed for the Battelle-Frankfurt D3, D6, and C9 tests. Descriptions of the two codes and the Battelle-Frankfurt experiments are included. Comparisons of the codes' calculations and experimental data for absolute pressure, differential pressure, and temperature are presented for margin evaluation. Evaluations of the sensitivity of BEACON calculations to variations in model noding, form loss, and vent area modeling are prsesented. Conclusions summarizing the results of the COMPARE margin evaluation and BEACON sensitivity studies are given as well.

  6. The dependence of the anisoplanatic Strehl of a compensated beam on the beacon distribution

    SciTech Connect

    Stroud, P.

    1992-02-07

    There are several applications for lasers where the effect of atmospheric turbulence is strong enough to require wavefront compensation, and the compensation can be made by an adaptive optics (AO) system which processes light returned from the target itself. The distribution of the target return light produces limitations to the performance of the AO system. The primary intent of this documentation is to present the new results of an analysis of the anisoplanatic effects arising from target return beacon geometries. It will also lay out the assumptions and steps in the analysis, so that the results can be validated or extended. The intent is to provide a self-consistent notation, simple physical interpretations of the mathematical formulations, and enough detail to reduce the investment of time required to become acquainted or reacquainted with the physics of laser propagation through turbulence, at a level needed to analyze anisoplanatic effects. A general formulation has been developed to calculate the anisoplanatic Strehl of a compensated beam for any beacon distribution and turbulence profile. Numerical calculations are also shown for several beacon geometries and turbulence profiles. The key result is that the spread of the beacon distribution has a much less deleterious effect than does the offset of the beacon centroid from the aimpoint.

  7. The dependence of the anisoplanatic Strehl of a compensated beam on the beacon distribution. Final report

    SciTech Connect

    Stroud, P.

    1992-02-07

    There are several applications for lasers where the effect of atmospheric turbulence is strong enough to require wavefront compensation, and the compensation can be made by an adaptive optics (AO) system which processes light returned from the target itself. The distribution of the target return light produces limitations to the performance of the AO system. The primary intent of this documentation is to present the new results of an analysis of the anisoplanatic effects arising from target return beacon geometries. It will also lay out the assumptions and steps in the analysis, so that the results can be validated or extended. The intent is to provide a self-consistent notation, simple physical interpretations of the mathematical formulations, and enough detail to reduce the investment of time required to become acquainted or reacquainted with the physics of laser propagation through turbulence, at a level needed to analyze anisoplanatic effects. A general formulation has been developed to calculate the anisoplanatic Strehl of a compensated beam for any beacon distribution and turbulence profile. Numerical calculations are also shown for several beacon geometries and turbulence profiles. The key result is that the spread of the beacon distribution has a much less deleterious effect than does the offset of the beacon centroid from the aimpoint.

  8. A spiral wave front beacon for underwater navigation: transducer prototypes and testing.

    PubMed

    Dzikowicz, Benjamin R; Hefner, Brian T

    2012-05-01

    Transducers for acoustic beacons which can produce outgoing signals with wave fronts whose horizontal cross sections are circular or spiral are studied experimentally. A remote hydrophone is used to determine its aspect relative to the transducers by comparing the phase of the circular signal to the phase of the spiral signal. The transducers for a "physical-spiral" beacon are made by forming a strip of 1-3 piezocomposite transducer material around either a circular or spiral backing. A "phased-spiral" beacon is made from an array of transducer elements which can be driven either in phase or staggered out of phase so as to produce signals with either a circular or spiral wave front. Measurements are made to study outgoing signals and their usefulness in determining aspect angle. Vertical beam width is also examined and phase corrections applied when the hydrophone is out of the horizontal plane of the beacon. While numerical simulations indicate that the discontinuity in the physical-spiral beacon introduces errors into the measured phase, damping observed at the ends of the piezocomposite material is a more significant source of error. This damping is also reflected in laser Doppler vibrometer measurements of the transducer's surface velocity.

  9. "Molecular beacon"-based fluorescent assay for selective detection of glutathione and cysteine.

    PubMed

    Xu, Hui; Hepel, Maria

    2011-02-01

    We report on the development of a fluorescence turn-on "molecular beacon" probe for the detection of glutathione (GSH) and cysteine (Cys). The method is based on a competitive ligation of Hg(2+) ions by GSH/Cys and thymine-thymine (T-T) mismatches in a DNA strand of the self-hybridizing beacon strand. The assay relies on the distance-dependent optical properties of the fluorophore/quencher pair attached to the ends of the molecular beacon DNA strand. In a very selective coordination of Hg(2+) to GSH/Cys, the fluorophore/quencher distance increases concomitantly with the dehybridization and dissociation of the beacon stem T-Hg(2+)-T due to the extraction of Hg(2+) ions. This process results in switching the molecular beacon to the "on" state. The concentration range of the probe is 4-200 nM with the limit of detection (LOD) of 4.1 nM for GSH and 4.2 nM Cys. The probe tested satisfactorily against interference for a range of amino acids including sulfur-containing methionine.

  10. A dual molecular beacon approach for fast detection of Mycobacterium tuberculosis.

    PubMed

    Yu, Chuan-Xing; Zhao, Zi-Yun; Lv, Jian-Xin; Zhu, Ling

    2013-02-01

    The main objectives of this study were to assess a dual molecular beacon approach for fast detection of Mycobacterium tuberculosis (MT). MT beacon (Tb-B) was designed to target the unique IS6110 (114 bp) and rpoB (215 bp) fragment of the MT (H37Ra) genome, and the two fragments were inserted into the PMD-19T vector after purification, by PCR and sequencing, to construct plasmids. Different dilutions of positive plasmid standards were used for dual molecular beacon RT-PCR of rpoB and IS6110, and standard curves were established.The results show that the dual molecular beacon of rpoB and IS6110 detecting MT was stable (CV is 1.91-2.68 %) with a high amplification efficiency (95.6 %). In addition, the strains of non MT did not generate fluorescence signals, while strains of MT did, indicating that the primers and molecular beacons were specific, and only MT complex was amplified. The linear range was wide (10(3)-10(11) copies/mL), and clinical specimens presenting different bacterial counts can be detected.

  11. Energy-Efficient BOP-Based Beacon Transmission Scheduling in Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Kim, Eui-Jik; Youm, Sungkwan; Choi, Hyo-Hyun

    Many applications in wireless sensor networks (WSNs) require the energy efficiency and scalability. Although IEEE 802.15.4/Zigbee which is being considered as general technology for WSNs enables the low duty-cycling with time synchronization of all the nodes in network, it still suffer from its low scalability due to the beacon frame collision. Recently, various algorithms to resolve this problem are proposed. However, their manners to implement are somewhat ambiguous and the degradation of energy/communication efficiency is serious by the additional overhead. This paper describes an Energy-efficient BOP-based Beacon transmission Scheduling (EBBS) algorithm. EBBS is the centralized approach, in which a resource-sufficient node called as Topology Management Center (TMC) allocates the time slots to transmit a beacon frame to the nodes and manages the active/sleep schedules of them. We also propose EBBS with Adaptive BOPL (EBBS-AB), to adjust the duration to transmit beacon frames in every beacon interval, adaptively. Simulation results show that by using the proposed algorithm, the energy efficiency and the throughput of whole network can be significantly improved. EBBS-AB is also more effective for the network performance when the nodes are uniformly deployed on the sensor field rather than the case of random topologies.

  12. Real-time quantitative nicking endonuclease-mediated isothermal amplification with small molecular beacons.

    PubMed

    Xu, Wentao; Wang, Chenguang; Zhu, Pengyu; Guo, Tianxiao; Xu, Yuancong; Huang, Kunlun; Luo, Yunbo

    2016-04-21

    Techniques of isothermal amplification have recently made great strides, and have generated significant interest in the field of point-of-care detection. Nicking endonuclease-mediated isothermal amplification (NEMA) is an example of simple isothermal technology. In this paper, a real-time quantitative nicking endonuclease-mediated isothermal amplification with small molecular beacons (SMB-NEMA) of improved specificity and sensitivity is described. First, we optimized the prohibition of de novo synthesis by choosing Nt·BstNBI endonuclease. Second, the whole genome was successfully amplified with Nt·BstNBI (6 U), betaine (1 M) and trehalose (60 mM) for the first time. Third, we achieved 10 pg sensitivity for the first time after adding a small molecular beacon that spontaneously undergoes a conformational change when hybridizing to target, and the practical test validated the assay's application. The small molecular beacon has a similar melting temperature to the reaction temperature, but is approximately 10 bp shorter than the length of a traditional molecular beacon. A new threshold regulation was also established for isothermal conditions. Finally, we established a thermodynamic model for designing small molecular beacons. This multistate model is more correct than the traditional algorithm. This theoretical and practical basis will help us to monitor SMB-NEMA in a quantitative way. In summary, our SMB-NEMA method allows the simple, specific and sensitive assessment of isothermal DNA quantification.

  13. Monitoring molecular beacon DNA probe hybridization at the single-molecule level.

    PubMed

    Yao, Gang; Fang, Xiaohong; Yokota, Hiroaki; Yanagida, Toshio; Tan, Weihong

    2003-11-21

    We have monitored the reaction dynamics of the DNA hybridization process on a liquid/solid interface at the single-molecule level by using a hairpin-type molecular beacon DNA probe. Fluorescence images of single DNA probes were recorded by using total internal reflection fluorescence microscopy. The fluorescence signal of single DNA probes during the hybridization to individual complementary DNA probes was monitored over time. Among 400 molecular beacon DNA probes that we tracked, 349 molecular beacons (87.5 %) were hybridized quickly and showed an abrupt fluorescence increase, while 51 probes (12.5 %) reacted slowly, resulting in a gradual fluorescence increase. This ratio stayed about the same when varying the concentrations of cDNA in MB hybridization on the liquid/surface interface. Statistical data of the 51 single-molecule hybridization images showed that there was a multistep hybridization process. Our results also showed that photostability for the dye molecules associated with the double-stranded hybrids was better than that for those with the single-stranded molecular beacon DNA probes. Our results demonstrate the ability to obtain a better understanding of DNA hybridization processes using single-molecule techniques, which will improve biosensor and biochip development where surface-immobilized molecular beacon DNA probes provide unique advantages in signal transduction.

  14. The influence of beacon-aiming on the routes of wood ants.

    PubMed

    Graham, Paul; Fauria, Karine; Collett, Thomas S

    2003-02-01

    Many insects have an innate propensity to approach conspicuous objects. We explore how such beacon aiming determines the shape of a wood ant's habitual route. We find that a single large black cylinder within an arena biases the route taken by ants as they run from a start position at one end of the arena to reach a feeder at the other. Ants learn a stable route with the first segment of their trajectory aimed at the cylinder, which becomes an intermediate goal on the way to the feeder. When in occasional tests the cylinder is removed or displaced, ants head for the usual site of the cylinder. They also aim for the same site when the cylinder is removed and the ant's normal start position is changed. This behaviour suggests that visual features of the arena are learnt from the vantage point of the cylinder and that this stored snapshot guides the ant to that site. Ants thus reinforce their ability to reach the cylinder by learning other visual features in their surroundings that can also steer them to its location. The use of beacon aiming in fixing routes has several benefits. Because the same path will be traversed on every trial, beacon aiming facilitates the acquisition of routes. Beacon aiming also increases the robustness of learnt routes: ants straying from the route will be attracted to the closest beacon and so regain their habitual paths.

  15. In vitro quantification of specific microRNA using molecular beacons.

    PubMed

    Baker, Meredith B; Bao, Gang; Searles, Charles D

    2012-01-01

    MicroRNAs (miRNAs), a class of non-coding RNAs, have become a major focus of molecular biology research because of their diverse genomic origin and ability to regulate an array of cellular processes. Although the biological functions of miRNA are yet to be fully understood, tissue levels of specific miRNAs have been shown to correlate with pathological development of disease. Here, we demonstrate that molecular beacons can readily distinguish mature- and pre-miRNAs, and reliably quantify miRNA expression. We found that molecular beacons with DNA, RNA and combined locked nucleic acid (LNA)-DNA backbones can all detect miRNAs of low (<1 nM) concentrations in vitro, with RNA beacons having the highest detection sensitivity. Furthermore, we found that molecular beacons have the potential to distinguish miRNAs that have slight variations in their nucleotide sequence. These results suggest that the molecular beacon-based approach to assess miRNA expression and distinguish mature and precursor miRNA species is quite robust, and has the promise for assessing miRNA levels in biological samples.

  16. Locked nucleic acid based beacons for surface interaction studies and biosensor development.

    PubMed

    Martinez, Karen; Estevez, M-Carmen; Wu, Yanrong; Phillips, Joseph A; Medley, Colin D; Tan, Weihong

    2009-05-01

    DNA sensors and microarrays permit fast, simple, and real-time detection of nucleic acids through the design and use of increasingly sensitive, selective, and robust molecular probes. Specifically, molecular beacons (MBs) have been employed for this purpose; however, their potential in the development of solid-surface-based biosensors has not been fully realized. This is mainly a consequence of the beacon's poor stability because of the hairpin structure once immobilized onto a solid surface, commonly resulting in a low signal enhancement. Here, we report the design of a new MB that overcomes some of the limitations of MBs for surface immobilization. Essentially, this new design adds locked nucleic acid bases (LNAs) to the beacon structure, resulting in a LNA molecular beacon (LMB) with robust stability after surface immobilization. To test the efficacy of LMBs against that of regular molecular beacons (RMBs), the properties of selectivity, sensitivity, thermal stability, hybridization kinetics, and robustness for the detection of target sequences were compared and evaluated. A 25-fold enhancement was achieved for the LMB on surface with detection limits reaching the low nanomolar range. In addition, the LMB-based biosensor was shown to possess better stability, reproducibility, selectivity, and robustness when compared to the RMB. Therefore, as an alternative to conventional DNA and as a prospective tool for use in both DNA microarrays and biosensors, these results demonstrate the potential of the locked nucleic acid bases for nucleic acid design for surface immobilization.

  17. Molecular beacon polymerase chain reaction detection of Escherichia coli O157:H7 in milk.

    PubMed

    McKillip, J L; Drake, M

    2000-07-01

    A fluorescently labeled oligonucleotide probe (molecular beacon) was applied to detect Escherichia coli O157:H7 in artificially contaminated skim milk during polymerase chain reaction (PCR) amplification of extracted DNA. The probe was designed to hybridize with a region of the slt-II gene coding for the A subunit and to fluoresce when the hairpin-stem conformation was linearized upon hybridization to the target sequence. The molecular beacon was incorporated into PCR reactions containing DNA extracted from artificially contaminated skim milk. The degree of fluorescence was monitored in PCR reactions containing 10(3), 10(5), and 10(7) CFU of E. coli O157:H7 per ml and was found to correlate with the amount of template in each reaction. Fluorescence significantly increased above background levels by cycle 8, 14, or 14 in reactions containing DNA from the 10(7)-, 10(5)-, or 10(3)-CFU/ml template, respectively (P < 0.05). Molecular beacon PCR demonstrated positive results more rapidly than traditional agarose gel electrophoresis analysis of PCR products. Use of molecular beacons allows real-time monitoring of PCR reactions, and the closed-tube format allows simultaneous detection and confirmation of target amplicons without the need for agarose gel electrophoresis and/or Southern blotting. This is the first report of a stem-and-loop molecular beacon being applied for direct detection of a pathogen in food.

  18. Visual format for detection of Mycobacterium tuberculosis and M. bovis in clinical samples using molecular beacons.

    PubMed

    Kumar, Parameet; Nath, Kapili; Rath, Bimba; Sen, Manas K; Vishalakshi, Potharuju; Chauhan, Devender S; Katoch, Vishwa M; Singh, Sarman; Tyagi, Sanjay; Sreenivas, Vishnubhatla; Prasad, Hanumanthappa K

    2009-09-01

    A real-time polymerase chain reaction (PCR) assay for the direct identification of Mycobacterium tuberculosis and M. bovis using molecular beacons was developed. The assay was modified for use in regular thermal cyclers. Molecular beacons that were specific for M. tuberculosis (Tb-B) and M. bovis (Bo-B) were designed. The fluorescence of the target PCR product-molecular beacon probe complex was detected visually using a transilluminator. The results were then compared with those of conventional multiplex PCR (CM-PCR) assays and biochemical identification. The detection limit of Tb-B and Bo-B beacons was 500 fg and 50 fg by the visual format and real-time PCR assay, respectively, compared with 5 pg by CM-PCR assay. Pulmonary and extrapulmonary samples were examined. The agreement between culture and the two assays was very good in sputum samples and fair in extrapulmonary samples. The agreement between clinical diagnoses with the two assays was moderate in extrapulmonary samples. There was very good agreement between CM-PCR and visual format assays for all samples used in the study. Concordance in the identification of isolates by the visual, CM-PCR assay, and biochemical identification was seen. Hence, the use of molecular beacon detection of M. tuberculosis and M. bovis in clinical samples is feasible by setting up two asymmetric PCRs concurrently. The assay is sensitive, specific, simple to interpret, and takes less than 3 hours to complete.

  19. Detection of toxoplasma gondii with a DNA molecular beacon probe

    NASA Astrophysics Data System (ADS)

    Xu, Shichao; Yao, Cuicui; Wei, Shuoming; Zhang, Jimei; Sun, Bo; Zheng, Guo; Han, Qing; Hu, Fei; Zhou, Hongming

    2008-12-01

    Toxoplasma gondii is a microscopic parasite that may infect humans, so there is an increasing concern on the early detection of latent Toxoplasma gondii infection in recent years. We currently report a rapid and sensitive method for Toxoplasma gondii based on molecular beacon (MB) probe. The probe based on fluorescence resonance energy transfer (FRET) with a stem-loop DNA oligonucleotide was labeled with CdTe/ZnS quantum dots (energy donor) at 5' end and BHQ-2 (energy acceptor) at 3' end, respectively. The probe was synthesized in PBS buffer at pH 8.2, room temperature for 24 h. Then target DNA was injected under the condition of 37°C, hybridization for 2 h, in Tris-HCl buffer. The data from fluorescence spectrum (FS) showed that ca 65% of emitted fluorescence was quenched, and about 50% recovery of fluorescence intensity was observed after adding target DNA, which indicated that the target DNA was successfully detected by MB probe. The detecting limitation was determined as ca 5 nM. Moreover, specificity of the probe was investigated by adding target DNA with one-base-pair mismatch, the low fluorescence recovery indicated the high specificity. The results showed that the current sensing probe will be a useful and convenient tool in Toxoplasma gondii early detection.

  20. Optical fiber nanotips coated with molecular beacons for DNA detection.

    PubMed

    Giannetti, Ambra; Barucci, Andrea; Cosi, Franco; Pelli, Stefano; Tombelli, Sara; Trono, Cosimo; Baldini, Francesco

    2015-04-24

    Optical fiber sensors, thanks to their compactness, fast response and real-time measurements, have a large impact in the fields of life science research, drug discovery and medical diagnostics. In recent years, advances in nanotechnology have resulted in the development of nanotools, capable of entering the single cell, resulting in new nanobiosensors useful for the detection of biomolecules inside living cells. In this paper, we provide an application of a nanotip coupled with molecular beacons (MBs) for the detection of DNA. The MBs were characterized by hybridization studies with a complementary target to prove their functionality both free in solution and immobilized onto a solid support. The solid support chosen as substrate for the immobilization of the MBs was a 30 nm tapered tip of an optical fiber, fabricated by chemical etching. With this set-up promising results were obtained and a limit of detection (LOD) of 0.57 nM was reached, opening up the possibility of using the proposed nanotip to detect mRNAs inside the cytoplasm of living cells.

  1. STEREO Space Weather and the Space Weather Beacon

    NASA Technical Reports Server (NTRS)

    Biesecker, D. A.; Webb, D F.; SaintCyr, O. C.

    2007-01-01

    The Solar Terrestrial Relations Observatory (STEREO) is first and foremost a solar and interplanetary research mission, with one of the natural applications being in the area of space weather. The obvious potential for space weather applications is so great that NOAA has worked to incorporate the real-time data into their forecast center as much as possible. A subset of the STEREO data will be continuously downlinked in a real-time broadcast mode, called the Space Weather Beacon. Within the research community there has been considerable interest in conducting space weather related research with STEREO. Some of this research is geared towards making an immediate impact while other work is still very much in the research domain. There are many areas where STEREO might contribute and we cannot predict where all the successes will come. Here we discuss how STEREO will contribute to space weather and many of the specific research projects proposed to address STEREO space weather issues. We also discuss some specific uses of the STEREO data in the NOAA Space Environment Center.

  2. Optical Fiber Nanotips Coated with Molecular Beacons for DNA Detection

    PubMed Central

    Giannetti, Ambra; Barucci, Andrea; Cosi, Franco; Pelli, Stefano; Tombelli, Sara; Trono, Cosimo; Baldini, Francesco

    2015-01-01

    Optical fiber sensors, thanks to their compactness, fast response and real-time measurements, have a large impact in the fields of life science research, drug discovery and medical diagnostics. In recent years, advances in nanotechnology have resulted in the development of nanotools, capable of entering the single cell, resulting in new nanobiosensors useful for the detection of biomolecules inside living cells. In this paper, we provide an application of a nanotip coupled with molecular beacons (MBs) for the detection of DNA. The MBs were characterized by hybridization studies with a complementary target to prove their functionality both free in solution and immobilized onto a solid support. The solid support chosen as substrate for the immobilization of the MBs was a 30 nm tapered tip of an optical fiber, fabricated by chemical etching. With this set-up promising results were obtained and a limit of detection (LOD) of 0.57 nM was reached, opening up the possibility of using the proposed nanotip to detect mRNAs inside the cytoplasm of living cells. PMID:25919369

  3. An elegant biosensor molecular beacon probe: challenges and recent solutions.

    PubMed

    Kolpashchikov, Dmitry M

    2012-01-01

    Molecular beacon (MB) probes are fluorophore- and quencher-labeled short synthetic DNAs folded in a stem-loop shape. Since the first report by Tyagi and Kramer, it has become a widely accepted tool for nucleic acid analysis and triggered a cascade of related developments in the field of molecular sensing. The unprecedented success of MB probes stems from their ability to detect specific DNA or RNA sequences immediately after hybridization with no need to wash out the unbound probe (instantaneous format). Importantly, the hairpin structure of the probe is responsible for both the low fluorescent background and improved selectivity. Furthermore, the signal is generated in a reversible manner; thus, if the analyte is removed, the signal is reduced to the background. This paper highlights the advantages of MB probes and discusses the approaches that address the challenges in MB probe design. Variations of MB-based assays tackle the problem of stem invasion, improve SNP genotyping and signal-to-noise ratio, as well as address the challenges of detecting folded RNA and DNA.

  4. Molecular beacon probes of oligonucleotides photodamaged by psoralen.

    PubMed

    Shire, Zahra J; Loppnow, Glen R

    2012-01-01

    Ultraviolet A (UVA)-irradiated 4'-hydroxymethyl-4,5',8-trimethyl psoralen (HMT) in the presence of a poly-dT(17) and dA(7) TTA(8) oligonucleotides produces HMT-dT(17) and HMT-dA(7) TTA(8) adducts in aqueous solution. In this article, we determine whether these HMT-dT(17) and HMT-dA(7) TTA(8) adducts can be detected with a molecular beacon (MB) probe. We measure the degree of damage in dT(17) and dA(7) TTA(8) solutions containing UVA-activated HMT via monitoring the decrease in MB fluorescence. Photoproduct formation is confirmed by MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-fight mass spectrometry measurements) and absorption spectroscopy. The MB fluorescence decreases upon UVA irradiation in the presence of HMT with a single-exponential time constants of 114.2 ± 6.5 min for HMT-dT(17) adducts and 677.8 ± 181.8 min for HMT-dA(7) TTA(8) adducts. Our results show that fluorescent MB probes are a selective, robust and accurate tool for detecting UVA-activated HMT-induced DNA damage.

  5. Molecular beacon probes of photodamage in thymine and uracil oligonucleotides.

    PubMed

    Yarasi, Soujanya; McConachie, Cheryl; Loppnow, Glen R

    2005-01-01

    Molecular beacons (MB) are becoming more common as sequence-selective detectors of nucleic acids. Although they can easily detect single-base mismatches, they have never been used to directly detect DNA or RNA damage. To measure the degree of ultraviolet (UV) light damage in oligonucleotides, we report a novel MB approach for general detection of photoproducts in UV-irradiated rU17 and dT17 oligonucleotides. With monochromatic UV light irradiation at ca 280 nm under anoxic conditions, the oligonucleotide absorption decays with a single-exponential time constant of 123+/-1 min for rU17 and with double-exponential time constants of 78+/-0.5 min (99%) and 180+/-5 min (0.05%) for dT17 oligonucleotides. Under the same conditions, the MB fluorescence decays more quickly, with single-exponential time constants of 19+/-2 and 26+/-3 min for rU17 and dT17, respectively. Similar kinetics were observed with broadband UV light irradiation of oligonucleotides. The differences in the UV damage kinetics of dT17 and rU17 and their detection by absorption and fluorescence techniques will be discussed in the context of differential instabilities introduced in the nucleic acid-MB duplex by the different photoproducts formed.

  6. Quantification of splice variants using molecular beacon or scorpion primers.

    PubMed

    Taveau, Mathieu; Stockholm, Daniel; Spencer, Melissa; Richard, Isabelle

    2002-06-15

    Uncovering the relationship between the generation of alternative transcripts and cellular processes is of crucial importance in the exploration of a gene's biology. The description and quantification of the spatiotemporal splicing pattern can be one method to select the most interesting transcripts for future studies. Fluorescence-based real-time quantitative RT-PCR has recently revolutionized the possibilities for transcriptional quantification studies. In this report, Molecular Beacon and Scorpion probes have been tested as new possibilities for determining the expression level of alternative transcripts. We validated these systems by analyzing alternative splicing of exons 6, 15, and 16 of the calpain 3 gene with tissues containing large variation in the ratio of the different transcripts. We determined conditions that demonstrated that boundary probes are useful tools and good alternatives to boundary primers, when developing a system to quantify specific transcripts. We suggest that the choice of a quantification system should depend in part on the structure and base composition of the gene and may have to be determined experimentally.

  7. Detection of DNA methyltransferase activity using allosteric molecular beacons.

    PubMed

    Zhang, Weiting; Zu, Xiaolong; Song, Yanling; Zhu, Zhi; Yang, Chaoyong James

    2016-01-21

    Abnormal DNA methylation patterns caused by altered DNA methyltransferase (MTase) activity are closely associated with cancer. Herein, using DNA adenine methylation methyltransferase (Dam MTase) as a model analyte, we designed an allosteric molecular beacon (aMB) for sensitive detection of Dam MTase activity. When the specific site in an aMB is methylated by Dam MTase, the probe can be cut by the restriction nuclease DpnI to release a fluorophore labeled aptamer specific for streptavidin (SA) which will bind to SA beads to generate highly fluorescent beads for easy signal readout by a microscope or flow cytometer. However, aMBs maintain a hairpin structure without the binding ability to SA beads in the absence of Dam MTase, leading to weakly fluorescent SA beads. Unlike the existing signal amplified assays, our method is simpler and more convenient. The high performance of the aptamer and the easy bead separation process make this probe superior to other methods for the detection of MTase in complex biological systems. Overall, the proposed method with a detection limit of 0.57 U mL(-1) for Dam MTase shows great potential for further applications in the detection of other MTases, screening of MTase inhibitors, and early diagnosis of cancer.

  8. Schizopsychotic symptom-profiles and biomarkers: beacons in diagnostic labyrinths.

    PubMed

    Palomo, Tomas; Kostrzewa, Richard M; Beninger, Richard J; Archer, Trevor

    2008-10-01

    Several avenues of investigation through which the 'labyrinths' of schizopsychotic diagnosis may be examined, are offered by the consideration of the 'beacons' of symptom-profiles and biomarkers. Neurodevelopmental issues and risk assessment, neurocognitive factors of predictive necessity, supersensitivity in neurotransmitter systems, the implications of prodromal expressions of the disorder, functional dysconnectivity arising from prefrontal to diverse regional patterns and circuits with a neurodevelopmental origin, and heritable gene characteristics are viewed against the backdrop of the schizophrenia spectrum disorders. The associations between adolescent-adult use of cannabis, on the one hand, and, alternatively, the prevalence of chromosomal abnormalities, e.g., GRIK4 and NPAS3, and mental retardation, on the other hand, with the symptom-profiles of schizopsychosis provide further evidence of emerging biomarkers of biological inheritance factors. The involvement of dopamine D1 and D2 receptors, particularly in prefrontal region, with regard to functional integrity of cognitive systems is reviewed. It would appear that considerations of these disorders imply that one essential hub around which much of the neuropathology revolves may be observed in the various expressions of the cognitive and structural insufficiency.

  9. An Elegant Biosensor Molecular Beacon Probe: Challenges and Recent Solutions

    PubMed Central

    Kolpashchikov, Dmitry M.

    2012-01-01

    Molecular beacon (MB) probes are fluorophore- and quencher-labeled short synthetic DNAs folded in a stem-loop shape. Since the first report by Tyagi and Kramer, it has become a widely accepted tool for nucleic acid analysis and triggered a cascade of related developments in the field of molecular sensing. The unprecedented success of MB probes stems from their ability to detect specific DNA or RNA sequences immediately after hybridization with no need to wash out the unbound probe (instantaneous format). Importantly, the hairpin structure of the probe is responsible for both the low fluorescent background and improved selectivity. Furthermore, the signal is generated in a reversible manner; thus, if the analyte is removed, the signal is reduced to the background. This paper highlights the advantages of MB probes and discusses the approaches that address the challenges in MB probe design. Variations of MB-based assays tackle the problem of stem invasion, improve SNP genotyping and signal-to-noise ratio, as well as address the challenges of detecting folded RNA and DNA. PMID:24278758

  10. Polar motion and earth tides from Beacon Explorer C

    NASA Technical Reports Server (NTRS)

    Kolenkiewicz, D. E.; Smith, D. E.; Dunn, P. J.

    1973-01-01

    Seventeen months of laser tracking of the Beacon Explorer C spacecraft by a Goddard Space Flight Center laser system were analyzed. The amplitude and phase of the solid-earth and ocean-tide perturbations of the orbit and the variation in latitude of the tracking station were determined. From an analysis of the orbital inclination obtained from 6 hour data spans the tidal perturbations of the orbit were found to have a magnitude equivalent to a second degree Love number, k sub 2, of 0.245 with a phase lag of about 3.2 degrees. These numbers are in complete agreement with values obtained previously from a much shorter data span, although k sub 2, is lower than the value derived from seismic data. This discrepancy is probably due to the influence of the oceans on the satellite result. After removing the tidal perturbations the residuals in inclination were of order 0.04 arcseconds. This implies that the variation in latitude of the station was being determined during the 17 months period with an rms deviation of about 1.4 meters with respect to the smoothed Bureau International de l'Heure values.

  11. A molecular beacon-based DNA switch for reversible pH sensing in vesicles and live cells.

    PubMed

    Narayanaswamy, Nagarjun; Nair, Raji R; Suseela, Y V; Saini, Deepak Kumar; Govindaraju, T

    2016-07-01

    In this Communication, a molecular beacon-based DNA switch (LMB) is developed as an efficient and reversible pH sensing probe. Remarkably, LMB exhibited reversible structural transition between the closed (molecular beacon) and open (A-motif) states very efficiently in synthetic vesicles and live cells without the need for any transfection agents. PMID:27338808

  12. Polarization Methods of Measuring the Roll Angle of an Object in Motion in Radio Beacon Navigation Systems

    NASA Astrophysics Data System (ADS)

    Gulko, V. L.; Mescheryakov, A. A.

    2016-06-01

    Polarization methods of measuring the roll angle of an object in motion with the help of radio beacon systems are considered. The polarization properties of the beacon signals received on board the object and amplitude-phase processing of their orthogonal polarized components are used to accomplish this goal.

  13. 75 FR 20364 - Public Buildings Service; Key Largo Beacon Annex Site; Key Largo, FL; Transfer of Property

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-19

    ... From the Federal Register Online via the Government Publishing Office GENERAL SERVICES ADMINISTRATION Public Buildings Service; Key Largo Beacon Annex Site; Key Largo, FL; Transfer of Property..., identified as Key Largo Beacon Annex Site, Key Largo, FL to the U.S. Fish and Wildlife Service, Department...

  14. A molecular beacon-based DNA switch for reversible pH sensing in vesicles and live cells.

    PubMed

    Narayanaswamy, Nagarjun; Nair, Raji R; Suseela, Y V; Saini, Deepak Kumar; Govindaraju, T

    2016-07-01

    In this Communication, a molecular beacon-based DNA switch (LMB) is developed as an efficient and reversible pH sensing probe. Remarkably, LMB exhibited reversible structural transition between the closed (molecular beacon) and open (A-motif) states very efficiently in synthetic vesicles and live cells without the need for any transfection agents.

  15. A spiral wave front beacon for underwater navigation: basic concept and modeling.

    PubMed

    Hefner, Brian T; Dzikowicz, Benjamin R

    2011-06-01

    A spiral wave front source produces an acoustic field that has a phase that is proportional to the azimuthal angle about the source. The concept of a spiral wave front beacon is developed by combining this source with a reference source that has a phase that is constant with the angle. The phase difference between these sources contains information about the receiver's azimuthal angle relative to the beacon and can be used for underwater navigation. To produce the spiral wave front, two sources are considered: a "physical-spiral" source, which produces the appropriate phase by physically deforming the active element of the source into a spiral, and a "phased-spiral" source, which uses an array of active elements, each driven with the appropriate phase, to produce the spiral wave front. Using finite element techniques, the fields produced by these sources are examined in the context of the spiral wave front beacon, and the advantages of each source are discussed.

  16. Development of satellite position location system for aircraft and boat distress beacons

    NASA Technical Reports Server (NTRS)

    Kahle, D. R.

    1982-01-01

    An international satellite system for the detection and location of distress beacons carried on aircraft and vessels is in its technical checkout phase. User demonstration and evaluation (D&E) will start in early 1983 and continue for two years. The D&E phase and a subsequent transition period will form the basis for improved search and rescue operations for the 1980's and beyond. The system, called COSPAS/SARSAT, has international participation involving the U.S., Canada, and France as SARSAT members and joint participation with the Soviet Union's COSPAS Project. Norway and the U.K. have recently joined as investigators. Average position location error of the satellite aided processing is expected to be from 10-20KM for the existing 121.5/243 MHz distress beacons and from 2-5KM for experimental beacons transmitting in the 406 MHz band.

  17. A beacon interval shifting scheme for interference mitigation in body area networks.

    PubMed

    Kim, Seungku; Kim, Seokhwan; Kim, Jin-Woo; Eom, Doo-Seop

    2012-01-01

    This paper investigates the issue of interference avoidance in body area networks (BANs). IEEE 802.15 Task Group 6 presented several schemes to reduce such interference, but these schemes are still not proper solutions for BANs. We present a novel distributed TDMA-based beacon interval shifting scheme that reduces interference in the BANs. A design goal of the scheme is to avoid the wakeup period of each BAN coinciding with other networks by employing carrier sensing before a beacon transmission. We analyze the beacon interval shifting scheme and investigate the proper back-off length when the channel is busy. We compare the performance of the proposed scheme with the schemes presented in IEEE 802.15 Task Group 6 using an OMNeT++ simulation. The simulation results show that the proposed scheme has a lower packet loss, energy consumption, and delivery-latency than the schemes of IEEE 802.15 Task Group 6.

  18. Using tRNA-linked molecular beacons to image cytoplasmic mRNAs in live cells.

    PubMed

    Mhlanga, Musa M; Tyagi, Sanjay

    2006-01-01

    Imaging products of gene expression in live cells will provide unique insights into the biology of cells. Molecular beacons make attractive probes for imaging mRNA in live cells as they can report the presence of an RNA target by turning on the fluorescence of a quenched fluorophore. However, when oligonucleotide probes are introduced into cells, they are rapidly sequestered in the nucleus, making the detection of cytoplasmic mRNAs difficult. We have shown that if a molecular beacon is linked to a tRNA, it stays in the cytoplasm and permits detection of cytoplasmic mRNAs. Here we describe two methods of linking molecular beacons to tRNA and show how the joint molecules can be used for imaging an mRNA that is normally present in the cytoplasm in live cultured cells. This protocol should take a total of 4 d to complete.

  19. Cleavable substrate containing molecular beacons for the quantification of DNA-photolyase activity.

    PubMed

    Kundu, Lal Mohan; Burgdorf, Lars T; Kleiner, Oliver; Batschauer, Alfred; Carell, Thomas

    2002-11-01

    In order to gain deeper insight into the function and interplay of proteins in cells it is essential to develop methods that allow the profiling of protein function in real time, in solution, in cells, and in cell organelles. Here we report the development of a U-type oligonucleotide (molecular beacon) that contains a fluorophore and a quencher at the tips, and in addition a substrate analogue in the loop structure. This substrate analogue induces a hairpin cleavage in response to enzyme action, which is translated into a fluorescence signal. The molecular beacon developed here was used to characterize DNA-photolyase activity. These enzymes represent a challenge for analytical methods because of their low abundance in cells. The molecular beacon made it possible to measure the activity of purified class I and class II photolyases. Photolyase activity was even detectable in crude cell extracts.

  20. Real-time quantification of RNA polymerase activity using a "broken beacon".

    PubMed

    Blair, Rebecca H; Rosenblum, Eric S; Dawson, Erica D; Kuchta, Robert D; Kuck, Laura R; Rowlen, Kathy L

    2007-03-15

    A novel assay using a hybridization-based method was developed for real-time monitoring of RNA synthesis. In this work, a "broken beacon" in which the fluor and quencher were located on separate but complementary oligonucleotides was used to quantify the amount of RNA production by T7 polymerase. The relative lengths of the fluor-oligo and quencher-oligo, and their relative concentrations were optimized. The experimentally determined limit-of-detection was approximately 45 nM. The new assay was compared to the "gold-standard" radiolabel ([(32)P]NTP incorporation) assay for RNA quantification. While the broken beacon assay exhibited a higher limit of detection, it provided an accurate measure of RNA production rates. However, the broken beacon assay provided the significant analytical advantages of (i) a real-time and continuous measurement, (ii) no requirement for the use of radiolabels or gel-based analysis, and (iii) substantial time and labor savings.

  1. Landmarks as beacons and associative cues: their role in route learning.

    PubMed

    Waller, David; Lippa, Yvonne

    2007-07-01

    Relatively little is known about how people use the landmarks in their environment to learn routes. Landmarks are commonly regarded as associative cues--stimuli that enable recall of directional responses that lead closer to the navigator's goal. We contrast the function of landmark as associative cue with that of a beacon-a landmark near enough to a goal that moving toward it leads the navigator closer to his or her goal. In five experiments, participants learned a route through a simple desktop virtual environment. In the first three experiments, routes were learned better when their landmarks served as beacons than as associative cues. Two additional experiments showed that the acquired route knowledge depends on the function that landmarks serve during learning. Beacon-based route knowledge is less enduring and relatively less likely to involve knowledge of directions in the environment than is the route knowledge formed from landmarks that serve as associative cues.

  2. Design and optimization of molecular beacon real-time polymerase chain reaction assays.

    PubMed

    Vet, Jacqueline A M; Marras, Salvatore A E

    2005-01-01

    During the last few years, several innovative technologies have become available for performing sensitive and accurate genetic analyses. These techniques use fluorescent detection strategies in combination with nucleic acid amplification protocols. Most commonly used is the real-time polymerase chain reaction (PCR). To achieve the maximum potential of a real-time PCR assay, several parameters must be evaluated and optimized independently. This chapter describes the different steps necessary for establishing a molecular beacon real-time PCR assay: (1) target design, (2) primer design, (3) optimization of the amplification reaction conditions using SYBR Green, (4) molecular beacon design, and (5) molecular beacon synthesis and characterization. The last section provides an example of a multiplex quantitative real-time PCR.

  3. Use of sloppy molecular beacon probes for identification of mycobacterial species.

    PubMed

    El-Hajj, Hiyam H; Marras, Salvatore A E; Tyagi, Sanjay; Shashkina, Elena; Kamboj, Mini; Kiehn, Timothy E; Glickman, Michael S; Kramer, Fred Russell; Alland, David

    2009-04-01

    We report here the use of novel "sloppy" molecular beacon probes in homogeneous PCR screening assays in which thermal denaturation of the resulting probe-amplicon hybrids provides a characteristic set of amplicon melting temperature (T(m)) values that identify which species is present in a sample. Sloppy molecular beacons possess relatively long probe sequences, enabling them to form hybrids with amplicons from many different species despite the presence of mismatched base pairs. By using four sloppy molecular beacons, each possessing a different probe sequence and each labeled with a differently colored fluorophore, four different T(m) values can be determined simultaneously. We tested this technique with 27 different species of mycobacteria and found that each species generates a unique, highly reproducible signature that is unaffected by the initial bacterial DNA concentration. Utilizing this general paradigm, screening assays can be designed for the identification of a wide range of species.

  4. A novel sensitive and selective ligation-based ATP assay using a molecular beacon.

    PubMed

    Ma, Changbei; Tang, Zhiwen; Wang, Kemin; Yang, Xiaohai; Tan, Weihong

    2013-05-21

    In this paper, a novel, facile fluorometric ATP assay with high sensitivity and excellent selectivity has been reported. This approach utilizes a molecular beacon, T4 DNA ligase and two short oligonucleotides. In the presence of ATP, the T4 DNA ligase catalyzes the ligation reaction and the ligation product restores the fluorescence of the molecular beacon. Owing to the high sensitivity of the molecular beacon and T4 DNA ligase's high substrate dependence, this novel ATP assay demonstrates exceptional selectivity and high sensitivity down to 0.14 nM in homogeneous solution. Cellular ATP concentrations in several cell lines have been determined by measuring the lysate sample containing 8.0 × 10(3) cells.

  5. Visual detection of Akt mRNA in living cell using gold nanoparticle beacon

    NASA Astrophysics Data System (ADS)

    Ma, Yi; Tian, Caiping; Li, Siwen; Wang, Zhaohui; Gu, Yueqing

    2014-09-01

    PI3K-Akt signaling pathway plays the key role in cell apoptosis and survival, and the components of PI3K /Akt signaling pathway are often abnormally expressed in human tumors. Therefore, determination of the Akt (protein kinase B, PKB) messenger ribonucleic acid (mRNA) expression is significantly important in understanding the mechanism of tumor progression. In this study, we designed a special hairpin deoxyribonucleic acid (DNA) functionalized with gold nanoparticles and fluorescein isothiocyanate(FITC) as a beacon for detecting human Akt mRNA. Spectrofluorometer was used to detect the fluorescence quenching and recovery of the beacons, and laser confocal scanning microscopy was adopted to image Akt mRNA in cells. The results showed that this beacon could sensitively and quantitatively measure the Akt mRNA in living cells . This strategy is potentially useful for the cellular imaging of RNA or protein expression in living cells.

  6. Development of an aptamer beacon for detection of interferon-gamma.

    PubMed

    Tuleuova, Nazgul; Jones, Caroline N; Yan, Jun; Ramanculov, Erlan; Yokobayashi, Yohei; Revzin, Alexander

    2010-03-01

    Traditional antibody-based affinity sensing strategies employ multiple reagents and washing steps and are unsuitable for real-time detection of analyte binding. Aptamers, on the other hand, may be designed to monitor binding events directly, in real-time, without the need for secondary labels. The goal of the present study was to design an aptamer beacon for fluorescence resonance energy transfer (FRET)-based detection of interferon-gamma (IFN-gamma)--an important inflammatory cytokine. Variants of DNA aptamer modified with biotin moieties and spacers were immobilized on avidin-coated surfaces and characterized by surface plasmon resonance (SPR). The SPR studies showed that immobilization of aptamer via the 3' end resulted in the best binding IFN-gamma (K(d) = 3.44 nM). This optimal aptamer variant was then used to construct a beacon by hybridizing fluorophore-labeled aptamer with an antisense oligonucleotide strand carrying a quencher. SPR studies revealed that IFN-gamma binding with an aptamer beacon occurred within 15 min of analyte introduction--suggesting dynamic replacement of the quencher-complementary strand by IFN-gamma molecules. To further highlight biosensing applications, aptamer beacon molecules were immobilized inside microfluidic channels and challenged with varying concentration of analyte. Fluorescence microscopy revealed low fluorescence in the absence of analyte and high fluorescence after introduction of IFN-gamma. Importantly, unlike traditional antibody-based immunoassays, the signal was observed directly upon binding of analyte without the need for multiple washing steps. The surface immobilized aptamer beacon had a linear range from 5 to 100 nM and a lower limit of detection of 5 nM IFN-gamma. In conclusion, we designed a FRET-based aptamer beacon for monitoring of an inflammatory cytokine-IFN-gamma. In the future, this biosensing strategy will be employed to monitor dynamics of cytokine production by the immune cells.

  7. Results from the northern New Mexico satellite-beacon radio interferometer

    SciTech Connect

    Carlos, R.; Jacobson, A.; Massey, R.; Wu, G.

    1994-09-01

    An interferometer described in the Boston, 1992, meeting of the Beacon Satellite Symposium has been in full operation for over a year now. It consists of four autonomous stations; three are in a triangle 70 km on a side and one is in the center. The stations receive the VHF beacons from two geosynchronous satellites, GOES-2 and ATS-3. The phases of the beacons are tracked at each station by referring them to an extremely stable rubidium oscillator. The studies of the two satellites are virtually separate experiments. The received phase of the beacon is retarded by the increased Total-Electron-Content of the dense regions of waves in the ionosphere. By comparing the phase history at four spatially separated stations, the authors can determine the two-dimensional propagation vector of the waves. This array is optimal for wavelengths of 70--300 km (periods of 300--3,000 seconds). Since the measurement is of the phase of the signal rather than the difference between the O-mode and X-mode phases, and since the beacons are in the VHF rather than in the L-band of GPS beacons, the array is very sensitive. It has a noise level of 10{sup 13} electrons/m{sup 2}, or 10{sup {minus}4} of the normal daytime TEC. This has been verified by operating two stations in the same location, so that they saw the same ionosphere. The first interesting results from a year`s study is that the authors do not see the same TID`s when looking at the two satellites. One conclusion they draw is that they do not see evidence of ionospheric winds.

  8. Building and Strengthening Infrastructure for Data Exchange: Lessons from the Beacon Communities

    PubMed Central

    Torres, Gretchen W.; Swietek, Karen; Ubri, Petry S.; Singer, Rachel F.; Lowell, Kristina H.; Miller, Wilhelmine

    2014-01-01

    Introduction: The Beacon Community Cooperative Agreement Program supports interventions, including care-delivery innovations, provider performance measurement and feedback initiatives, and tools for providers and consumers to enhance care. Using a learning health system framework, we examine the Beacon Communities’ processes in building and strengthening health IT (HIT) infrastructures, specifically successes and challenges in sharing patient information to improve clinical care. Background: In 2010, the Office of the National Coordinator for Health Information Technology (ONC) launched the three-year program, which provided $250 million to 17 Beacon Communities to invest in HIT and health information exchange (HIE) infrastructure. Beacon Communities used this funding to develop and disseminate HIT-enabled quality improvement practices found effective in particular community and practice environments. Methods: NORC conducted 7 site visits, November 2012–March 2013, selecting Communities to represent diverse program features. From August–October 2013, NORC held discussions with the remaining 10 Communities. Following each visit or discussion, NORC summarized the information gathered, including transcripts, team observations, and other documents the Community provided, to facilitate a within-Community analysis of context and stakeholders, intervention strategies, enabling factors, and challenges. Results: Although each Community designed and implemented data-sharing strategies in a unique environment, similar challenges and enabling factors emerged across the Beacons. From a learning health system perspective, their strategies to build and strengthen data-sharing infrastructures address the following crosscutting priorities: promoting technical advances and innovations by helping providers adapt EHRs for data exchange and performance measurement with customizable IT and offering technical support to smaller, independent providers; engaging key stakeholders; and

  9. p53-Dependent activation of a molecular beacon in tumor cells following exposure to doxorubicin chemotherapy.

    PubMed

    Shah, Rishita; El-Deiry, Wafik S

    2004-09-01

    In an effort to begin developing a non-invasive strategy for in-vivo detection of the cellular DNA damage response, we engineered a molecular beacon to detect expression of p21(WAF1/CIP1), a gene whose transcription is directly activated by the p53 tumor suppressor protein. Introduction of a phosphorothioate-modified p21-beacon by transfection in human tumor cells led to a slight background signal that increased in a dose dependent manner between 50 and 400 nM beacon. Strong nuclear signal was observed following treatment of wild-type p53-expressing human H460 lung cancer cells for 8 hours with the chemotherapeutic agent doxorubicin (adriamycin). Similar induction was observed in wild-type p53-expressing HCT116 cells. Interestingly, following doxorubicin exposure, there was activation of the p21-beacon in p21-null HCT116 cells, which was not observed in p53-null HCT116, or mutant p53-expressing DLD1 cells that are either wild-type or p21-null. Increased signal from the phosphorothioate-modified p21-beacon in doxorubicin-treated cells likely resulted from sequence-specific hybridization as well as sequence-independent cleavage that may occur due to p53-dependent activation of endonucleases during apoptosis. We conclude that activation of p53 by chemotherapy leads to a strong signal from a p21-beacon that may be useful in further testing both in vitro and in vivo. Strategies need to be developed to optimize the gene or damage specificity as well as the sensitivity to therapeutic response of this non-invasive imaging approach.

  10. Time-Resolved Nucleic Acid Hybridization Beacons Utilizing Unimolecular and Toehold-Mediated Strand Displacement Designs.

    PubMed

    Massey, Melissa; Ancona, Mario G; Medintz, Igor L; Algar, W Russ

    2015-12-01

    Nucleic acid hybridization probes are sought after for numerous assay and imaging applications. These probes are often limited by the properties of fluorescent dyes, prompting the development of new probes where dyes are paired with novel or nontraditional luminescent materials. Luminescent terbium complexes are an example of such a material, and these complexes offer several unique spectroscopic advantages. Here, we demonstrate two nonstem-loop designs for light-up nucleic acid hybridization beacons that utilize time-resolved Förster resonance energy transfer (TR-FRET) between a luminescent Lumi4-Tb cryptate (Tb) donor and a fluorescent reporter dye, where time-resolved emission from the dye provides an analytical signal. Both designs are based on probe oligonucleotides that are labeled at their opposite termini with Tb and a fluorescent reporter dye. In one design, a probe is partially blocked with a quencher dye-labeled oligonucleotide, and target hybridization is signaled through toehold-mediated strand displacement and loss of a competitive FRET pathway. In the other design, the intrinsic folding properties of an unblocked probe are utilized in combination with a temporal mechanism for signaling target hybridization. This temporal mechanism is based on a recently elucidated "sweet spot" for TR-FRET measurements and exploits distance control over FRET efficiencies to shift the Tb lifetime within or outside the time-gated detection window for measurements. Both the blocked and unblocked beacons offer nanomolar (femtomole) detection limits, response times on the order of minutes, multiplexing through the use of different reporter dyes, and detection in complex matrices such as serum and blood. The blocked beacons offer better mismatch selectivity, whereas the unblocked beacons are simpler in design. The temporal mechanism of signaling utilized with the unblocked beacons also plays a significant role with the blocked beacons and represents a new and effective

  11. HRO: A New Forward-Scatter Observation Method Using a Ham-Band Beacon

    NASA Astrophysics Data System (ADS)

    Maegawa, K.

    1999-02-01

    A new forward-scatter meteor observation method has been used since 1996 in Japan. It uses its own 50 W continuous wave beacon with a broad directivity antenna on 53.750 MHz. To compensate for the weak echo power from the beacon, observers use SSB mode receivers and narrow band echo detection methods with Fast Fourier Transform software on personal computers. More than 250000 echoes have been counted per year so far. >From these results, diurnal and seasonal variations have been derived and are presented and discussed here. This method (HRO) will continue to play a leading radio observation role in Japan for the future.

  12. Geostationary-satellite beacon-receiver array for studies of ionospheric irregularities

    SciTech Connect

    Carlos, R.C.; Jacobson, A.R.; Wu, Guanghui

    1992-09-01

    Ionospheric irregularities can be studied by various techniques. These include widely spaced Doppler sounders or ionosondes, Faraday rotation polarimetry, and two-frequency differential Doppler, and radio interferometry. With geostationary satellites, one usually uses Faraday rotation of the beacon signal to measure the ionospheric TEC. With a network of polarimeters, the horizontal wave parameters of Traveling Ionospheric Disturbances (TIDS) can be deduced, but the shortcoming of this technique is its poor sensitivity. This paper describes a geostationary-satellite beacon-receiver array at Los Alamos, New Mexico, which will be employed for the studying of ionospheric irregularities, especially the fine-scale TIDS.

  13. Geostationary-satellite beacon-receiver array for studies of ionospheric irregularities

    SciTech Connect

    Carlos, R.C.; Jacobson, A.R.; Wu, Guanghui.

    1992-01-01

    Ionospheric irregularities can be studied by various techniques. These include widely spaced Doppler sounders or ionosondes, Faraday rotation polarimetry, and two-frequency differential Doppler, and radio interferometry. With geostationary satellites, one usually uses Faraday rotation of the beacon signal to measure the ionospheric TEC. With a network of polarimeters, the horizontal wave parameters of Traveling Ionospheric Disturbances (TIDS) can be deduced, but the shortcoming of this technique is its poor sensitivity. This paper describes a geostationary-satellite beacon-receiver array at Los Alamos, New Mexico, which will be employed for the studying of ionospheric irregularities, especially the fine-scale TIDS.

  14. A transfection reporter for the prevention of false-negative results in molecular beacon experiments.

    PubMed

    Toga, Tatsuya; Kuraoka, Isao; Yasui, Akira; Iwai, Shigenori

    2013-09-01

    We previously developed a molecular beacon-type probe to detect the strand scission in cellular base excision repair and found that the phosphodiester linkages in the fluorophore/quencher linkers were cleaved. This reaction was applied to a transfection reporter, which contained the unmodified phosphodiester in the linker to another type of fluorophore. After cotransfection of cells with the probe and the reporter, the signals were used to detect the incision and to confirm the proper transfection, respectively. This method will contribute to the prevention of false-negative results in experiments using molecular beacon-type probes.

  15. Beacon communities aim to use health information technology to transform the delivery of care.

    PubMed

    Maxson, Emily R; Jain, Sachin H; McKethan, Aaron N; Brammer, Craig; Buntin, Melinda Beeuwkes; Cronin, Kelly; Mostashari, Farzad; Blumenthal, David

    2010-09-01

    The Beacon Community Program, authorized under the 2009 American Recovery and Reinvestment Act (ARRA), aims to demonstrate the potential for health information technology to enable local improvements in health care quality, cost efficiency, and population health. If successful, these communitywide efforts will yield important lessons that will assist other communities seeking to harness technology to achieve and sustain health care improvements. This paper highlights key programmatic details that reflect the meaningful use of technology in the fifteen Beacon communities. It describes the innovations they propose and provides insight into current and future challenges.

  16. Effects of different beacon wavelengths on atmospheric compensation in strong scintillation.

    PubMed

    Fan, Chengyu; Wang, Yingjian; Gong, Zhiben

    2004-08-01

    During strong scintillation, the number and location of branch points in a distorted optical field induced by atmospheric turbulence are closely related to the characteristic parameters of the turbulence effect, propagation distance, and wavelength. It is necessary to consider the effect of the beacon's wavelength on the adaptive optics system that is used to compensate for atmospheric turbulence. Our analytical results show that the performance of adaptive optics can be improved by nearly a factor of 2 when the beacon's wavelength is chosen slightly longer than the wavelength of the main laser in the branch points considered.

  17. Real-time monitoring of double-stranded DNA cleavage using molecular beacons.

    PubMed

    Ma, Changbei; Tang, Zhiwen; Huo, Xiqin; Yang, Xiaohai; Li, Wei; Tan, Weihong

    2008-07-15

    Traditional methods to assay enzymatic cleavage of DNA are discontinuous, time-consuming and laborious. Here, we report a new approach for real-time monitoring of double-stranded DNA cleavage by restriction endonuclease based on nucleic acid ligation using molecular beacon. Upon cleavage of DNA, the cleavage product can be ligated by DNA ligase, which results in a fluorescence enhancement of the molecular beacon. This method permits real-time monitoring of DNA cleavage and makes it easy to characterize the activity of restriction endonuclease and to study the cleavage reaction kinetics.

  18. Use of RNA polymerase molecular beacon assay to measure RNA polymerase interactions with model promoter fragments.

    PubMed

    Mekler, Vladimir; Severinov, Konstantin

    2015-01-01

    RNA polymerase-promoter interactions that keep the transcription initiation complex together are complex and multipartite, and formation of the RNA polymerase-promoter complex proceeds through multiple intermediates. Short promoter fragments can be used as a tool to dissect RNA polymerase-promoter interactions and to pinpoint elements responsible for specific properties of the entire promoter complex. A recently developed fluorometric molecular beacon assay allows one to monitor the enzyme interactions with various DNA probes and quantitatively characterize partial RNA polymerase-promoter interactions. Here, we present detailed protocols for the preparation of an Escherichia coli molecular beacon and its application to study RNA polymerase interactions with model promoter fragments.

  19. Lunar radio-beacons and geodetic VLBI system for determination of physical libration of the Moon

    NASA Astrophysics Data System (ADS)

    Gusev, Alexander; Hanada, Hideo; Kikuchi, Fuyuhiko; Matsumoto, Koji; Kosov, Alexander; Nefedyev, Yuri; Petrova, Natalia; Ping, Jinsong; Titov, Oleg

    Many space agencies plan a lunar missions, including scientific observations in the near lunar space and/or on the surface of the Moon. One of these experiments propose to place two landers with radio beacons on the Lunar near side and to launch one or more Orbiters on the Lunar orbit. The difference of the distances between two radio beacons and Earth will be assumed to be measured by the methods of Inverse VLBI: radio-signal from the various radio beacons will be sent to Earth antenna systems using the Orbiter. The estimation of the physical libration angle accuracy is made for various location and configuration of the radio beacons, which are in polar or equatorial zones of the Moon. The planned accuracy of difference distance determination for radio beacons at 60- 100 mm and the length of base line of 1700-3400 km in the Inverse VLBI experiment will be sufficient to improve accuracy of lunar physical libration, better than 10-30 msec of arc. Analogous estimation of latitude libration has shown the same results: location of the Radio Beacon I and Radio Beacon II in the vicinity of the Lunar limb equator and the prime meridian will give the best estimations for the physical libration angeles. For radio beacons experiment the best accuracy of longitudinal and latitudinal librations will be achieved in the equatorial limb and polar zones of the Moon. Geodetic VLBI network managed by the International VLBI Service provides high accurate positions of the reference radio sources, radio telescope coordinates, Earth Orientation Parameters (EOP), etc. A small radio telescope being installed on the Moon surface and incorporated to this existing network will help to improve these traditional IVS products by a factor of ten or even more. In addition, this new instrument will be able to detect some known effects with an unprecedented accuracy, and new effects which are not available for other ground-based instruments or space missions. The main navigational task is to

  20. A complementary palette of NanoCluster Beacons.

    PubMed

    Obliosca, Judy M; Babin, Mark C; Liu, Cong; Liu, Yen-Liang; Chen, Yu-An; Batson, Robert A; Ganguly, Mainak; Petty, Jeffrey T; Yeh, Hsin-Chih

    2014-10-28

    NanoCluster Beacons (NCBs), which use few-atom DNA-templated silver clusters as reporters, are a type of activatable molecular probes that are low-cost and easy to prepare. While NCBs provide a high fluorescence enhancement ratio upon activation, their activation colors are currently limited. Here we report a simple method to design NCBs with complementary emission colors, creating a set of multicolor probes for homogeneous, separation-free detection. By systematically altering the position and the number of cytosines in the cluster-nucleation sequence, we have tuned the activation colors of NCBs to green (C8-8, 460 nm/555 nm); yellow (C5-5, 525 nm/585 nm); red (C3-4, 580 nm/635 nm); and near-infrared (C3-3, 645 nm/695 nm). At the same NCB concentration, the activated yellow NCB (C5-5) was found to be 1.3 times brighter than the traditional red NCB (C3-4). Three of the four colors (green, yellow, and red) were relatively spectrally pure. We also found that subtle changes in the linker sequence (down to the single-nucleotide level) could significantly alter the emission spectrum pattern of an NCB. When the length of linker sequences was increased, the emission peaks were found to migrate in a periodic fashion, suggesting short-range interactions between silver clusters and nucleobases. Size exclusion chromatography results indicated that the activated NCBs are more compact than their native duplex forms. Our findings demonstrate the unique photophysical properties and environmental sensitivities of few-atom DNA-templated silver clusters, which are not seen before in common organic dyes or luminescent crystals.

  1. Rationally designed molecular beacons for bioanalytical and biomedical applications.

    PubMed

    Zheng, Jing; Yang, Ronghua; Shi, Muling; Wu, Cuichen; Fang, Xiaohong; Li, Yinhui; Li, Jishan; Tan, Weihong

    2015-05-21

    Nucleic acids hold promise as biomolecules for future applications in biomedicine and biotechnology. Their well-defined structures and compositions afford unique chemical properties and biological functions. Moreover, the specificity of hydrogen-bonded Watson-Crick interactions allows the construction of nucleic acid sequences with multiple functions. In particular, the development of nucleic acid probes as essential molecular engineering tools will make a significant contribution to advancements in biosensing, bioimaging and therapy. The molecular beacon (MB), first conceptualized by Tyagi and Kramer in 1996, is an excellent example of a double-stranded nucleic acid (dsDNA) probe. Although inactive in the absence of a target, dsDNA probes can report the presence of a specific target through hybridization or a specific recognition-triggered change in conformation. MB probes are typically fluorescently labeled oligonucleotides that range from 25 to 35 nucleotides (nt) in length, and their structure can be divided into three components: stem, loop and reporter. The intrinsic merit of MBs depends on predictable design, reproducibility of synthesis, simplicity of modification, and built-in signal transduction. Using resonance energy transfer (RET) for signal transduction, MBs are further endowed with increased sensitivity, rapid response and universality, making them ideal for chemical sensing, environmental monitoring and biological imaging, in contrast to other nucleic acid probes. Furthermore, integrating MBs with targeting ligands or molecular drugs can substantially support their in vivo applications in theranositics. In this review, we survey advances in bioanalytical and biomedical applications of rationally designed MBs, as they have evolved through the collaborative efforts of many researchers. We first discuss improvements to the three components of MBs: stem, loop and reporter. The current applications of MBs in biosensing, bioimaging and therapy will then

  2. Development of BEACON technology. Quarterly report, October-December 1981

    SciTech Connect

    Not Available

    1982-09-01

    The BEACON process involves the catalytic deposition of a highly reactive carbon from a gas stream containing carbon monoxide. The carbon-depleted gas is combusted with air to produce power, and the carbon is reacted with steam to produce methane. Laboratory multicycle tests with K1 and K2 catalysts were completed this quarter. Both catalysts were cycled through 40 deposition and steaming cycles. Both catalysts showed good stability. The K1-based material was found to be more active than the K2-based material, both for carbon deposition and for steaming. Gas conversion proceeded to near-equilibrium levels for both catalysts. Investigation of the effects of multicycle operation and carbon loading levels on catalyst C77-K2 stability continued this quarter. Testing in a 1-inch quartz fluid bed reactor showed no significant catalyst deterioration after 40 cycles at low carbon loadings. However, significant morphology changes occurred at higher carbon loadings. During testing in a new 1-1/2 inch diameter fluid bed reactor, there was evidence of inadequate mixing: large variations in carbon loading within the bed were observed, and the bed plugged at the higher carbon loadings. Multicycle testing of K1 and K2 catalysts continued in the 4-inch diameter fluid bed reactor. The K1 catalyst showed no decrease in catalytic activity after 9-1/2 of the planned 30 cycles. The K2 catalyst showed evidence of contamination from an undetermined source, and testing was discontinued after 9 cycles. A tandem reactor system which will circulate solids between a carbon deposition reactor and a carbon steaming reactor is now being designed for future catalyst testing. 19 figures, 21 tables.

  3. A Complementary Palette of NanoCluster Beacons

    PubMed Central

    2015-01-01

    NanoCluster Beacons (NCBs), which use few-atom DNA-templated silver clusters as reporters, are a type of activatable molecular probes that are low-cost and easy to prepare. While NCBs provide a high fluorescence enhancement ratio upon activation, their activation colors are currently limited. Here we report a simple method to design NCBs with complementary emission colors, creating a set of multicolor probes for homogeneous, separation-free detection. By systematically altering the position and the number of cytosines in the cluster-nucleation sequence, we have tuned the activation colors of NCBs to green (C8–8, 460 nm/555 nm); yellow (C5–5, 525 nm/585 nm); red (C3–4, 580 nm/635 nm); and near-infrared (C3–3, 645 nm/695 nm). At the same NCB concentration, the activated yellow NCB (C5–5) was found to be 1.3 times brighter than the traditional red NCB (C3–4). Three of the four colors (green, yellow, and red) were relatively spectrally pure. We also found that subtle changes in the linker sequence (down to the single-nucleotide level) could significantly alter the emission spectrum pattern of an NCB. When the length of linker sequences was increased, the emission peaks were found to migrate in a periodic fashion, suggesting short-range interactions between silver clusters and nucleobases. Size exclusion chromatography results indicated that the activated NCBs are more compact than their native duplex forms. Our findings demonstrate the unique photophysical properties and environmental sensitivities of few-atom DNA-templated silver clusters, which are not seen before in common organic dyes or luminescent crystals. PMID:25299363

  4. Perlecan domain V therapy for stroke: a beacon of hope?

    PubMed

    Bix, Gregory J

    2013-03-20

    The sad reality is that in the year 2012, people are still dying or suffering from the extreme morbidity of ischemic stroke. This tragedy is only compounded by the graveyard full of once promising new therapies. While it is indeed true that the overall mortality from stroke has declined in the United States, perhaps due to increased awareness of stroke symptoms by both the lay public and physicians, it is clear that better therapies are needed. In this regard, progress has been tremendously slowed by the simple fact that experimental models of stroke and the animals that they typically employ, rats and mice, do not adequately represent human stroke. Furthermore, the neuroprotective therapeutic approach, in which potential treatments are administered with the hope of preventing the spread of dying neurons that accompanies a stroke, typically fail for a number of reasons such as there is simply more brain matter to protect in a human than there is in a rodent! For this reason, there has been somewhat of a shift in stroke research away from neuroprotection and toward a neurorepair approach. This too may be problematic in that agents that might foster brain repair could be acutely deleterious or neurotoxic and vice versa, making the timing of treatment administration after stroke critical. Therefore, in our efforts to discover a new stroke therapy, we decided to focus on identifying brain repair elements that were (1) endogenously and actively generated in response to stroke in both human and experimental animal brains, (2) present acutely and chronically after ischemic stroke, suggesting that they could have a role in acute neuroprotection and chronic neurorepair, and (3) able to be administered peripherally and reach the site of stroke brain injury. In this review, I will discuss the evidence that suggests that perlecan domain V may be just that substance, a potential beacon of hope for stroke patients.

  5. Health assessment for Beacon Heights Landfill National Priorities List (NPL) Site, Beacon Falls, Connecticut, Region 1. CERCLIS No. CTD001145671. Final report

    SciTech Connect

    Not Available

    1989-01-26

    The Beacon Heights Landfill National Priorities List (NPL) Site is located in Beacon Falls, Connecticut. From the 1920's to 1979, municipal and industrial wastes were disposed of at the landfill. Leachate from the landfill has migrated into the local groundwater aquifers. Two residential wells to the northwest of the site have been contaminated with site-related contaminants. This site is of potential public health concern because of the risk to human health resulting from possible exposure to hazardous substances at concentrations that may result in adverse health effects. Human exposure to benzene, chlorobenzene, chloroethane, and methylene chloride may have occurred via ingestion, inhalation, and direct dermal contact with contaminated groundwater. No health study follow-up is indicated at this time.

  6. Fusing range measurements from ultrasonic beacons and a laser range finder for localization of a mobile robot.

    PubMed

    Ko, Nak Yong; Kuc, Tae-Yong

    2015-01-01

    This paper proposes a method for mobile robot localization in a partially unknown indoor environment. The method fuses two types of range measurements: the range from the robot to the beacons measured by ultrasonic sensors and the range from the robot to the walls surrounding the robot measured by a laser range finder (LRF). For the fusion, the unscented Kalman filter (UKF) is utilized. Because finding the Jacobian matrix is not feasible for range measurement using an LRF, UKF has an advantage in this situation over the extended KF. The locations of the beacons and range data from the beacons are available, whereas the correspondence of the range data to the beacon is not given. Therefore, the proposed method also deals with the problem of data association to determine which beacon corresponds to the given range data. The proposed approach is evaluated using different sets of design parameter values and is compared with the method that uses only an LRF or ultrasonic beacons. Comparative analysis shows that even though ultrasonic beacons are sparsely populated, have a large error and have a slow update rate, they improve the localization performance when fused with the LRF measurement. In addition, proper adjustment of the UKF design parameters is crucial for full utilization of the UKF approach for sensor fusion. This study contributes to the derivation of a UKF-based design methodology to fuse two exteroceptive measurements that are complementary to each other in localization. PMID:25970259

  7. Fusing Range Measurements from Ultrasonic Beacons and a Laser Range Finder for Localization of a Mobile Robot

    PubMed Central

    Ko, Nak Yong; Kuc, Tae-Yong

    2015-01-01

    This paper proposes a method for mobile robot localization in a partially unknown indoor environment. The method fuses two types of range measurements: the range from the robot to the beacons measured by ultrasonic sensors and the range from the robot to the walls surrounding the robot measured by a laser range finder (LRF). For the fusion, the unscented Kalman filter (UKF) is utilized. Because finding the Jacobian matrix is not feasible for range measurement using an LRF, UKF has an advantage in this situation over the extended KF. The locations of the beacons and range data from the beacons are available, whereas the correspondence of the range data to the beacon is not given. Therefore, the proposed method also deals with the problem of data association to determine which beacon corresponds to the given range data. The proposed approach is evaluated using different sets of design parameter values and is compared with the method that uses only an LRF or ultrasonic beacons. Comparative analysis shows that even though ultrasonic beacons are sparsely populated, have a large error and have a slow update rate, they improve the localization performance when fused with the LRF measurement. In addition, proper adjustment of the UKF design parameters is crucial for full utilization of the UKF approach for sensor fusion. This study contributes to the derivation of a UKF-based design methodology to fuse two exteroceptive measurements that are complementary to each other in localization. PMID:25970259

  8. Detection of single nucleotide variations by a hybridization proximity assay based on molecular beacons and luminescence resonance energy transfer.

    PubMed

    Root, Douglas D; Vaccaro, Carlos; Zhang, Zhiling; Castro, Miguel

    2004-09-01

    A powerful combination of molecular beacon and luminescence resonance energy transfer technology reveals alterations in nucleic acid structure by as little as a single nucleotide in a novel hybridization proximity assay. The assay measures the length of a single-stranded target when a terbium chelate-labeled molecular beacon hybridizes to one side of the nucleic acid segment to be measured and an acceptor probe carrying a convention fluorophore hybridizes to the opposite end of the target. Using a test sequence shortened incrementally by deleting single nucleotides, this assay reports a nearly linear relationship between sequence length and the distance separating acceptor and donor probes. Consequently, this assay can be used to detect alternative splicing, allele types, rearrangements, insertion, and deletion events by measuring separation distances within a predefined region. Furthermore, the use of terbium chelates in molecular beacons can produce exceptionally high signal-to-background ratios compared to the use of conventional fluorophores. Principles of optimal probe design are investigated experimentally and by computational simulations of plausible molecular beacon folding. Some molecular beacon designs form dimers that reduce their maximal response to target sequences. A simple assay to detect such dimers is reported as a tool to help improve the design of molecular beacons. Optimally designed molecular beacons with terbium chelates and hybridization proximity assays are expected to expand their applications in the analysis and screening of genetic diseases.

  9. Fusing range measurements from ultrasonic beacons and a laser range finder for localization of a mobile robot.

    PubMed

    Ko, Nak Yong; Kuc, Tae-Yong

    2015-01-01

    This paper proposes a method for mobile robot localization in a partially unknown indoor environment. The method fuses two types of range measurements: the range from the robot to the beacons measured by ultrasonic sensors and the range from the robot to the walls surrounding the robot measured by a laser range finder (LRF). For the fusion, the unscented Kalman filter (UKF) is utilized. Because finding the Jacobian matrix is not feasible for range measurement using an LRF, UKF has an advantage in this situation over the extended KF. The locations of the beacons and range data from the beacons are available, whereas the correspondence of the range data to the beacon is not given. Therefore, the proposed method also deals with the problem of data association to determine which beacon corresponds to the given range data. The proposed approach is evaluated using different sets of design parameter values and is compared with the method that uses only an LRF or ultrasonic beacons. Comparative analysis shows that even though ultrasonic beacons are sparsely populated, have a large error and have a slow update rate, they improve the localization performance when fused with the LRF measurement. In addition, proper adjustment of the UKF design parameters is crucial for full utilization of the UKF approach for sensor fusion. This study contributes to the derivation of a UKF-based design methodology to fuse two exteroceptive measurements that are complementary to each other in localization.

  10. Visual detection of STAT5B gene expression in living cell using the hairpin DNA modified gold nanoparticle beacon.

    PubMed

    Xue, Jianpeng; Shan, Lingling; Chen, Haiyan; Li, Yang; Zhu, Hongyan; Deng, Dawei; Qian, Zhiyu; Achilefu, Samuel; Gu, Yueqing

    2013-03-15

    Signal transducer and activator of transcription 5B (STAT5B) is an important protein in JAK-STAT signaling pathway that is responsible for the metastasis and proliferation of tumor cells. Determination of the STAT5B messenger Ribonucleic Acid (mRNA) relating to the STAT5B expression provides insight into the mechanism of tumor progression. In this study, we designed and used a special hairpin deoxyribonucleic acid (DNA) for human STAT5B mRNA to functionalize gold nanoparticles, which served as a beacon for detecting human STAT5B expression. Up to 90% quenching efficiency was achieved. Upon hybridizing with the target mRNA, the hairpin DNA modified gold nanoparticle beacons (hDAuNP beacons) release the fluorophores attached at 5' end of the oligonucleotide sequence. The fluorescence properties of the beacon before and after the hybridization with the complementary DNA were confirmed in vitro. The stability of hDAuNP beacons against degradation by DNase I and GSH indicated that the prepared beacon is stable inside cells. The detected fluorescence in MCF-7 cancer cells correlates with the specific STAT5B mRNA expression, which is consistent with the result from PCR measurement. Fluorescence microscopy showed that the hDAuNP beacons internalized in cells without using transfection agents, with intracellular distribution in the cytoplasm rather than the nucleus. The results demonstrated that this beacon could directly provide quantitative measurement of the intracellular STAT5B mRNA in living cells. Compared to the previous approaches, this beacon has advantages of higher target to background ratio of detection and an increased resistance to nuclease degradation. The strategy reported in this study is a promising approach for the intracellular measurement of RNA or protein expression in living cells, and has great potential in the study of drug screening and discovery.

  11. Hybridization of DNA and PNA molecular beacons to single-stranded and double-stranded DNA targets.

    PubMed

    Kuhn, Heiko; Demidov, Vadim V; Coull, James M; Fiandaca, Mark J; Gildea, Brian D; Frank-Kamenetskii, Maxim D

    2002-02-13

    Molecular beacons are sensitive fluorescent probes hybridizing selectively to designated DNA and RNA targets. They have recently become practical tools for quantitative real-time monitoring of single-stranded nucleic acids. Here, we comparatively study the performance of a variety of such probes, stemless and stem-containing DNA and PNA (peptide nucleic acid) beacons, in Tris-buffer solutions containing various concentrations of NaCl and MgCl(2). We demonstrate that different molecular beacons respond differently to the change of salt concentration, which could be attributed to the differences in their backbones and constructions. We have found that the stemless PNA beacon hybridizes rapidly to the complementary oligodeoxynucleotide and is less sensitive than the DNA beacons to the change of salt thus allowing effective detection of nucleic acid targets under various conditions. Though we found stemless DNA beacons improper for diagnostic purposes due to high background fluorescence, we believe that use of these DNA and similar RNA constructs in molecular-biophysical studies may be helpful for analysis of conformational flexibility of single-stranded nucleic acids. With the aid of PNA "openers", molecular beacons were employed for the detection of a chosen target sequence directly in double-stranded DNA (dsDNA). Conditions are found where the stemless PNA beacon strongly discriminates the complementary versus mismatched dsDNA targets. Together with the insensitivity of PNA beacons to the presence of salt and DNA-binding/processing proteins, the latter results demonstrate the potential of these probes as robust tools for recognition of specific sequences within dsDNA without denaturation and deproteinization of duplex DNA.

  12. Impacts of Fog Characteristics, Forward Illumination, and Warning Beacon Intensity Distribution on Roadway Hazard Visibility.

    PubMed

    Bullough, John D; Rea, Mark S

    2016-01-01

    Warning beacons are critical for the safety of transportation, construction, and utility workers. These devices need to produce sufficient luminous intensity to be visible without creating glare to drivers. Published standards for the photometric performance of warning beacons do not address their performance in conditions of reduced visibility such as fog. Under such conditions light emitted in directions other than toward approaching drivers can create scattered light that makes workers and other hazards less visible. Simulations of visibility of hazards under varying conditions of fog density, forward vehicle lighting, warning beacon luminous intensity, and intensity distribution were performed to assess their impacts on visual performance by drivers. Each of these factors can influence the ability of drivers to detect and identify workers and hazards along the roadway in work zones. Based on the results, it would be reasonable to specify maximum limits on the luminous intensity of warning beacons in directions that are unlikely to be seen by drivers along the roadway, limits which are not included in published performance specifications.

  13. A nanocluster beacon based on the template transformation of DNA-templated silver nanoclusters.

    PubMed

    Teng, Ye; Jia, Xiaofang; Zhang, Shan; Zhu, Jinbo; Wang, Erkang

    2016-01-28

    In this work, we developed a novel light-up nanocluster beacon (NCB) based on shuttling dark silver nanoclusters (NCs) to a bright scaffold through hybridization. The fluorescence enhancement was as high as 70-fold when the two templates were on the opposite sides of the duplexes, enabling sensitive and selective detection of DNA.

  14. Leveraging Health IT to Reduce Disparities in Three Underserved Beacon Communities.

    PubMed

    Des Jardins, Terrisca; Drone, Shenetta A; Hashisaka, Susan; Hazzard, Jobyna; Hunt, Susan B; Massey, Kimberly; Rein, Alison; Schachter, Abigail; Turske, Scott

    2016-01-01

    Using health information technology (IT) can potentially address health disparities by increasing access to care, delivering higher-quality care, improving patient-provider communication, and enhancing patient safety. It describes challenges encountered by three underserved Beacon Communities that implemented health IT interventions, including inadequate connectivity infrastructure, technical support, expertise, and financial resources; provider shortages and staff turnover; and equipment theft.

  15. Leveraging Health IT to Reduce Disparities in Three Underserved Beacon Communities.

    PubMed

    Des Jardins, Terrisca; Drone, Shenetta A; Hashisaka, Susan; Hazzard, Jobyna; Hunt, Susan B; Massey, Kimberly; Rein, Alison; Schachter, Abigail; Turske, Scott

    2016-01-01

    Using health information technology (IT) can potentially address health disparities by increasing access to care, delivering higher-quality care, improving patient-provider communication, and enhancing patient safety. It describes challenges encountered by three underserved Beacon Communities that implemented health IT interventions, including inadequate connectivity infrastructure, technical support, expertise, and financial resources; provider shortages and staff turnover; and equipment theft. PMID:27180682

  16. Standard and AEGIS nicking molecular beacons detect amplicons from the Middle East respiratory syndrome coronavirus.

    PubMed

    Yaren, Ozlem; Glushakova, Lyudmyla G; Bradley, Kevin M; Hoshika, Shuichi; Benner, Steven A

    2016-10-01

    This paper combines two advances to detect MERS-CoV, the causative agent of Middle East Respiratory Syndrome, that have emerged over the past few years from the new field of "synthetic biology". Both are based on an older concept, where molecular beacons are used as the downstream detection of viral RNA in biological mixtures followed by reverse transcription PCR amplification. The first advance exploits the artificially expanded genetic information systems (AEGIS). AEGIS adds nucleotides to the four found in standard DNA and RNA (xNA); AEGIS nucleotides pair orthogonally to the A:T and G:C pairs. Placing AEGIS components in the stems of molecular beacons is shown to lower noise by preventing unwanted stem invasion by adventitious natural xNA. This should improve the signal-to-noise ratio of molecular beacons operating in complex biological mixtures. The second advance introduces a nicking enzyme that allows a single target molecule to activate more than one beacon, allowing "signal amplification". Combining these technologies in primers with components of a self-avoiding molecular recognition system (SAMRS), we detect 50 copies of MERS-CoV RNA in a multiplexed respiratory virus panel by generating fluorescence signal visible to human eye and/or camera. PMID:27421627

  17. Impacts of Fog Characteristics, Forward Illumination, and Warning Beacon Intensity Distribution on Roadway Hazard Visibility.

    PubMed

    Bullough, John D; Rea, Mark S

    2016-01-01

    Warning beacons are critical for the safety of transportation, construction, and utility workers. These devices need to produce sufficient luminous intensity to be visible without creating glare to drivers. Published standards for the photometric performance of warning beacons do not address their performance in conditions of reduced visibility such as fog. Under such conditions light emitted in directions other than toward approaching drivers can create scattered light that makes workers and other hazards less visible. Simulations of visibility of hazards under varying conditions of fog density, forward vehicle lighting, warning beacon luminous intensity, and intensity distribution were performed to assess their impacts on visual performance by drivers. Each of these factors can influence the ability of drivers to detect and identify workers and hazards along the roadway in work zones. Based on the results, it would be reasonable to specify maximum limits on the luminous intensity of warning beacons in directions that are unlikely to be seen by drivers along the roadway, limits which are not included in published performance specifications. PMID:27314058

  18. The Roles of Beaconing and Dead Reckoning in Human Virtual Navigation

    ERIC Educational Resources Information Center

    Bodily, Kent D.; Daniel, Thomas A.; Sturz, Bradley R.

    2012-01-01

    Beaconing is a process in which the distance between a visual landmark and current position is reduced in order to return to a location. In contrast, dead reckoning is a process in which vestibular, kinesthetic and/or optic flow cues are utilized to update speed of movement, elapsed time of movement, and direction of movement to return to a…

  19. Sequential strand displacement beacon for detection of DNA coverage on functionalized gold nanoparticles.

    PubMed

    Paliwoda, Rebecca E; Li, Feng; Reid, Michael S; Lin, Yanwen; Le, X Chris

    2014-06-17

    Functionalizing nanomaterials for diverse analytical, biomedical, and therapeutic applications requires determination of surface coverage (or density) of DNA on nanomaterials. We describe a sequential strand displacement beacon assay that is able to quantify specific DNA sequences conjugated or coconjugated onto gold nanoparticles (AuNPs). Unlike the conventional fluorescence assay that requires the target DNA to be fluorescently labeled, the sequential strand displacement beacon method is able to quantify multiple unlabeled DNA oligonucleotides using a single (universal) strand displacement beacon. This unique feature is achieved by introducing two short unlabeled DNA probes for each specific DNA sequence and by performing sequential DNA strand displacement reactions. Varying the relative amounts of the specific DNA sequences and spacing DNA sequences during their coconjugation onto AuNPs results in different densities of the specific DNA on AuNP, ranging from 90 to 230 DNA molecules per AuNP. Results obtained from our sequential strand displacement beacon assay are consistent with those obtained from the conventional fluorescence assays. However, labeling of DNA with some fluorescent dyes, e.g., tetramethylrhodamine, alters DNA density on AuNP. The strand displacement strategy overcomes this problem by obviating direct labeling of the target DNA. This method has broad potential to facilitate more efficient design and characterization of novel multifunctional materials for diverse applications. PMID:24848126

  20. Time reversal ultrasound focusing to a point away from the beacon location

    NASA Astrophysics Data System (ADS)

    Sinelnikov, Yegor; Sutin, Alexander; Gandhi, Gaurav; Sarvazyan, Armen

    2012-10-01

    In percutaneous procedures there is often a need to focus therapeutic ultrasound to a predefined area without affecting surrounding tissues. Focusing based on Time Reversal Acoustics (TRA) principles constitutes a promising approach for generating high intensity ultrasound field tailored to the shape of the predefined area. Conventional TRA technique enables ultrasound focusing only at a site, where there is an ultrasound beacon, e.g. piezo-transducer mounted at the tip of a catheter. We developed a method of steering the focus away from the beacon location. The method is based on the measurements of impulse response (IR) in several reference points and calculating virtual IRs for the points outside the reference beacon location. The IR for the point away from the beacon is constructed based on mathematical extrapolation of the measured reference IRs frequency spectra, particularly phases. The effectiveness of extrapolated TRA focusing is explored experimentally and by computer simulation. Potential applications include ultrasounda-ssisted drug delivery, artery recanalization and tumor ablation.

  1. A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs.

    PubMed

    Mo, Yuanfu; Yu, Dexin; Song, Jun; Zheng, Kun; Guo, Yajuan

    2015-01-01

    In a vehicular ad hoc network (VANET), the periodic exchange of single-hop status information broadcasts (beacon frames) produces channel loading, which causes channel congestion and induces information conflict problems. To guarantee fairness in beacon transmissions from each node and maximum network connectivity, adjustment of the beacon transmission power is an effective method for reducing and preventing channel congestion. In this study, the primary factors that influence wireless channel loading are selected to construct the KF-BCLF, which is a channel load forecasting algorithm based on a recursive Kalman filter and employs multiple regression equation. By pre-adjusting the transmission power based on the forecasted channel load, the channel load was kept within a predefined range; therefore, channel congestion was prevented. Based on this method, the CLF-BTPC, which is a transmission power control algorithm, is proposed. To verify KF-BCLF algorithm, a traffic survey method that involved the collection of floating car data along a major traffic road in Changchun City is employed. By comparing this forecast with the measured channel loads, the proposed KF-BCLF algorithm was proven to be effective. In addition, the CLF-BTPC algorithm is verified by simulating a section of eight-lane highway and a signal-controlled urban intersection. The results of the two verification process indicate that this distributed CLF-BTPC algorithm can effectively control channel load, prevent channel congestion, and enhance the stability and robustness of wireless beacon transmission in a vehicular network.

  2. The New York City Beacons: Rebuilding Communities of Support in Urban Neighborhoods

    ERIC Educational Resources Information Center

    Kleinbard, Peter

    2005-01-01

    The first ten New York City Beacons began operation in 1991 as a result of the recommendation of a commission appointed by then-mayor David N. Dinkins. Richard Murphy, commissioner of youth services, led the development and implementation. Michele Cahill served as a consultant in the design and created the Youth Development Institute (YDI) as part…

  3. Sequential strand displacement beacon for detection of DNA coverage on functionalized gold nanoparticles.

    PubMed

    Paliwoda, Rebecca E; Li, Feng; Reid, Michael S; Lin, Yanwen; Le, X Chris

    2014-06-17

    Functionalizing nanomaterials for diverse analytical, biomedical, and therapeutic applications requires determination of surface coverage (or density) of DNA on nanomaterials. We describe a sequential strand displacement beacon assay that is able to quantify specific DNA sequences conjugated or coconjugated onto gold nanoparticles (AuNPs). Unlike the conventional fluorescence assay that requires the target DNA to be fluorescently labeled, the sequential strand displacement beacon method is able to quantify multiple unlabeled DNA oligonucleotides using a single (universal) strand displacement beacon. This unique feature is achieved by introducing two short unlabeled DNA probes for each specific DNA sequence and by performing sequential DNA strand displacement reactions. Varying the relative amounts of the specific DNA sequences and spacing DNA sequences during their coconjugation onto AuNPs results in different densities of the specific DNA on AuNP, ranging from 90 to 230 DNA molecules per AuNP. Results obtained from our sequential strand displacement beacon assay are consistent with those obtained from the conventional fluorescence assays. However, labeling of DNA with some fluorescent dyes, e.g., tetramethylrhodamine, alters DNA density on AuNP. The strand displacement strategy overcomes this problem by obviating direct labeling of the target DNA. This method has broad potential to facilitate more efficient design and characterization of novel multifunctional materials for diverse applications.

  4. The Effects of a Rectangular Rapid-Flashing Beacon on Vehicle Speed

    ERIC Educational Resources Information Center

    VanWagner, Michelle; Van Houten, Ron; Betts, Brian

    2011-01-01

    In 2008, nearly 31% of vehicle fatalities were related to failure to adhere to safe vehicle speeds (National Highway Traffic Safety Administration [NHTSA], 2009). The current study evaluated the effect of a rectangular rapid-flashing beacon (RRFB) triggered by excessive speed on vehicle speed using a combined alternating treatments and reversal…

  5. Beacon of Hope: The Promise of Early Head Start for America's Youngest Children

    ERIC Educational Resources Information Center

    Lombardi, Joan, Ed.; Bogle, Mary M., Ed.

    2005-01-01

    Between 1995 and 2004, Early Head Start (EHS) grew from 68 to more than 700 programs nationwide, serving more than 62,000 children and securing the program's reputation as a beacon of hope for the nation's low-income families with infants and toddlers. According to a comprehensive 5-year national evaluation of EHS, children who participated in…

  6. X/X/Ka-band prime focus feed antenna for the Mars Observer beacon spacecraft

    NASA Technical Reports Server (NTRS)

    Stanton, P.; Reilly, H.; Esquivel, M.

    1988-01-01

    The results of an X/X/Ka-band feed design concept demonstration are presented. The purpose is to show the feasibility of adding a Ka-band beacon to the Mars Observer spacecraft. Scale model radiation patterns were made and analyzed.

  7. Working Together To Build Beacon Centers in San Francisco: Evaluation Findings from 1998-2000.

    ERIC Educational Resources Information Center

    Walker, Karen E.; Arbreton, Amy J. A.

    The Beacons Initiative aimed to transform eight public schools (five middle schools and three high schools) into youth and family centers in low-income neighborhoods in San Francisco, California. Using a coalition of local partners and funding from public agencies and foundations, the centers served 7,500 youth and adults between July 1, 1999, and…

  8. After-School Pursuits: An Examination of Outcomes in the San Francisco Beacon Initiative

    ERIC Educational Resources Information Center

    Walker, Karen E.; Arbreton, Amy J.A.

    2004-01-01

    The San Francisco Beacon Initiative (SFBI) has been in effect in the San Francisco Unified School District since 1996. A collaboration of public and private funders, SFBI operates comprehensive after-school programs in six middle schools, one elementary school and one high school. Public/Private Ventures' (P/PV's) evaluation found that SFBI…

  9. Stem-loop oligonucleotide beacons as switches for amplifying-fluorescent-polymer-based biological warfare sensors

    NASA Astrophysics Data System (ADS)

    Clinkenbeard, Kenneth D.; Ramachandran, Akhilesh; Malayer, Jerry R.; Moon, Joong Ho; Hancock, Lawrence F.

    2003-09-01

    Sensors that are exceptionally sensitive with real-time outputs and minimal consumption of reagents are needed to continuously monitor air and water against bioterrorist incidents. Amplifying fluorescent polymers (AFP) provide exceptionally sensitive real-time reagentless sensor platforms as applied to detection of nitroaromatic explosives. This platform technology has the potential to be adapted to detect biological warfare (BW) agents by covalently attaching the 5" end of stem-loop molecular beacons to AFP as DNA hybridization signal transduction switches. Molecular beacons with loop sequences specific for sequence signatures of a target BW agent are configured with a quencher on the end of the 3" arm of the stem-loop. The AFP is quenched in the absence of target DNA, but upon hybridization with target the stem is melted, the duplex loop extended, and the AFP dequenched. This signal transduction is reversible upon removal of the target sequence with the molecular beacon reforming the stem-loop conformation. Proof-of-concept research has demonstrated that molecular beacons for signature sequences of Francisella tularensis result in correct identification of the presence of this agent in samples, but no false positives were seen with Escherichia coli.

  10. A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs.

    PubMed

    Mo, Yuanfu; Yu, Dexin; Song, Jun; Zheng, Kun; Guo, Yajuan

    2015-01-01

    In a vehicular ad hoc network (VANET), the periodic exchange of single-hop status information broadcasts (beacon frames) produces channel loading, which causes channel congestion and induces information conflict problems. To guarantee fairness in beacon transmissions from each node and maximum network connectivity, adjustment of the beacon transmission power is an effective method for reducing and preventing channel congestion. In this study, the primary factors that influence wireless channel loading are selected to construct the KF-BCLF, which is a channel load forecasting algorithm based on a recursive Kalman filter and employs multiple regression equation. By pre-adjusting the transmission power based on the forecasted channel load, the channel load was kept within a predefined range; therefore, channel congestion was prevented. Based on this method, the CLF-BTPC, which is a transmission power control algorithm, is proposed. To verify KF-BCLF algorithm, a traffic survey method that involved the collection of floating car data along a major traffic road in Changchun City is employed. By comparing this forecast with the measured channel loads, the proposed KF-BCLF algorithm was proven to be effective. In addition, the CLF-BTPC algorithm is verified by simulating a section of eight-lane highway and a signal-controlled urban intersection. The results of the two verification process indicate that this distributed CLF-BTPC algorithm can effectively control channel load, prevent channel congestion, and enhance the stability and robustness of wireless beacon transmission in a vehicular network. PMID:26571042

  11. Detection of murine norovirus-1 by using TAT peptide-delivered molecular beacons.

    PubMed

    Ganguli, Payal S; Chen, Wilfred; Yates, Marylynn V

    2011-08-01

    A TAT peptide-delivered molecular beacon was developed and utilized to enumerate murine norovirus 1, a human norovirus (NoV) surrogate, in RAW 264.7 cells. This allowed the detection of a single infective virus within 6 h, a 12-fold improvement in time required for viral detection and quantification compared to that required by the conventional plaque assay.

  12. Highly sensitive detection of alkaline phosphatase using molecular beacon probes based on enzymatic polymerization.

    PubMed

    Ma, Changbei

    2012-06-01

    We have developed a new methodology for highly sensitive alkaline phosphatase assay using molecular beacon probes. No incubation step is needed to obtain a limit of detection for ALP of 2×10(-16) M. Furthermore, ALP inhibition by the inhibitor okadaic acid is shown, demonstrating the potential for high-throughput screening for inhibitors.

  13. Real-time PCR detection of telomerase activity using specific molecular beacon probes.

    PubMed

    Kong, Deming; Jin, Yawei; Yin, Yuji; Mi, Huaifeng; Shen, Hanxi

    2007-06-01

    Telomerase is a potentially important biomarker and a prognostic indicator of cancer. Several techniques for assessing telomerase activity, including the telomeric repeat amplification protocol (TRAP) and its modified versions, have been developed. Of these methods, real-time quantitative TRAP (RTQ-TRAP) is considered the most promising. In this work, a novel RTQ-TRAP method is developed in which a telomeric repeats-specific molecular beacon is used. The use of the molecular beacon can improve the specificity of the RTQ-TRAP assay, making the method suitable for studying the overall processivity results and the turnover rate of telomerase. In addition, the real-time, closed-tube protocol used obviates the need for post-amplification procedures, reduces the risk of carryover contamination, and supports high throughput. Its performance in synthetic telomerase products and cell extracts suggests that the developed molecular beacon assay can further enhance the clinical utility of telomerase activity as a biomarker/indicator in cancer diagnosis and prognosis. The method also provides a novel approach to the specific detection of some particular gene sequences to which sequence-specific fluorogenic probes cannot be applied directly. Figure Real-time PCR detection of telomerase activity using specific molecular beacon probes.

  14. Ag nanocluster-based label-free catalytic and molecular beacons for amplified biosensing.

    PubMed

    Gong, Liang; Kuai, Hailan; Ren, Songlei; Zhao, Xu-Hua; Huan, Shuang-Yan; Zhang, Xiao-Bing; Tan, Weihong

    2015-08-01

    By employing DNAzyme as a recognition group and amplifier, and DNA-stabilized silver nanoclusters (DNA/AgNCs) as signal reporters, we reported for the first time a label-free catalytic and molecular beacon as an amplified biosensing platform for highly selective detection of cofactors such as Pb(2+) and L-histidine.

  15. Transport and detection of unlabeled nucleotide targets by microtubules functionalized with molecular beacons.

    PubMed

    Raab, Matthew; Hancock, William O

    2008-03-01

    Shrinking biosensors down to microscale dimensions enables increases in sensitivity and the ability to analyze minute samples such as the contents of individual cells. The goal of the present study is to create mobile microscale biosensors by attaching molecular beacons to microtubules and using kinesin molecular motors to transport these functionalized microtubules across two-dimensional surfaces. Previous work has shown that microfluidic channels can be functionalized with kinesin motors such that microtubules can be transported and directed through these channels without the need for external power or pressure-driven pumping. In this work, we show that molecular beacons can be attached to microtubules such that both the fluorescence reporting capability of the beacon and the motility of the microtubules are retained. These molecular beacon-functionalized microtubules were able to bind ssDNA target sequences, transport them across surfaces, and report their presence by an increase in fluorescence that was detected by fluorescence microscopy. This work is an important step toward creating hybrid microdevices for sensitive virus detection or analyzing mRNA profiles of individual cells.

  16. Molecular beacon-metal nanowire interface: effect of probe sequence and surface coverage on sensor performance.

    PubMed

    Cederquist, Kristin B; Stoermer Golightly, Rebecca; Keating, Christine D

    2008-08-19

    We report the effect of surface coverage and sequence on the performance of 5' thiolated, 3' fluorophore-labeled DNA hairpin probes bound to Au/Ag striped ("barcoded") metal nanowires. Coverage was controlled by varying probe concentration, buffer ionic strength, and by addition of short hydroxy-terminated alkanethiol diluent molecules during probe assembly onto the nanowire surface. Surface dilution of the surface-bound probes with a omega-hydroxyl alkanethiol, a commonly accepted practice in the surface-bound DNA literature, did not appreciably improve sensor performance as compared to similar probe coverages without hydroxyalkanethiol diluents; this finding underscores the differences between the molecular beacon probes used here and more traditional nonfluorescent, random coil probes. We found that intermediate probe coverage of approximately 10 (12) molecules/cm (2) gave the best discrimination between presence and absence of a target sequence. Because we are interested in multiplexed assays, we also compared several beacon probe sequences having different stabilities for secondary structure formation in solution; we found that both probe surface coverage and sensor performance varied for different probe sequences. When five different molecular beacon probes, each bound to barcoded nanowires, were used in a multiplexed, wash-free assay for target oligonucleotides corresponding to viral nucleic acid sequences, these differences in probe performance did not prevent accurate target identification. We anticipate that the findings described here will also be relevant to other applications involving molecular beacons or other structured nucleic acid probes immobilized on metal surfaces.

  17. Molecular aptamer beacon tuned DNA strand displacement to transform small molecules into DNA logic outputs.

    PubMed

    Zhu, Jinbo; Zhang, Libing; Zhou, Zhixue; Dong, Shaojun; Wang, Erkang

    2014-03-28

    A molecular aptamer beacon tuned DNA strand displacement reaction was introduced in this work. This strand displacement mode can be used to transform the adenosine triphosphate (ATP) input into a DNA strand output signal for the downstream gates to process. A simple logic circuit was built on the basis of this mechanism.

  18. Molecular-beacon multiplex real-time PCR assay for detection of Vibrio cholerae.

    PubMed

    Gubala, Aneta J; Proll, David F

    2006-09-01

    A multiplex real-time PCR assay was developed using molecular beacons for the detection of Vibrio cholerae by targeting four important virulence and regulatory genes. The specificity and sensitivity of this assay, when tested with pure culture and spiked environmental water samples, were high, surpassing those of currently published PCR assays for the detection of this organism.

  19. Holographic correction of large telescope primaries by proximal, off-axis beacons.

    PubMed

    Andersen, G; Munch, J; Veitch, P

    1996-02-01

    Compact telescope configurations incorporating a holographic correction of large, low-quality primary collectors are demonstrated. Aberration correction is demonstrated with an off-axis laser beacon located close to the primary. This arrangement results in a compact telescope with minimum obscuration. The reduction of additional off-axis aberrations introduced by the method is also demonstrated.

  20. Standard and AEGIS nicking molecular beacons detect amplicons from the Middle East respiratory syndrome coronavirus.

    PubMed

    Yaren, Ozlem; Glushakova, Lyudmyla G; Bradley, Kevin M; Hoshika, Shuichi; Benner, Steven A

    2016-10-01

    This paper combines two advances to detect MERS-CoV, the causative agent of Middle East Respiratory Syndrome, that have emerged over the past few years from the new field of "synthetic biology". Both are based on an older concept, where molecular beacons are used as the downstream detection of viral RNA in biological mixtures followed by reverse transcription PCR amplification. The first advance exploits the artificially expanded genetic information systems (AEGIS). AEGIS adds nucleotides to the four found in standard DNA and RNA (xNA); AEGIS nucleotides pair orthogonally to the A:T and G:C pairs. Placing AEGIS components in the stems of molecular beacons is shown to lower noise by preventing unwanted stem invasion by adventitious natural xNA. This should improve the signal-to-noise ratio of molecular beacons operating in complex biological mixtures. The second advance introduces a nicking enzyme that allows a single target molecule to activate more than one beacon, allowing "signal amplification". Combining these technologies in primers with components of a self-avoiding molecular recognition system (SAMRS), we detect 50 copies of MERS-CoV RNA in a multiplexed respiratory virus panel by generating fluorescence signal visible to human eye and/or camera.

  1. Influence of a beacon on spatial learning based on the shape of the test environment.

    PubMed

    Pearce, J M; Ward-Robinson, J; Good, M; Fussell, C; Aydin, A

    2001-10-01

    In 5 experiments rats were required to escape from a triangular shaped pool by swimming to a submerged platform. The principal group of interest in each experiment received training with a beacon attached to the platform. The purpose of the experiments was to assess if the beacon overshadowed (Experiments 1-4) or blocked (Experiment 5) learning about the position of the platform with reference to the shape of the pool. The platform was located in the center of the pool for the first 2 experiments and in a corner for the remaining experiments. Although there was an overshadowing effect in Experiment 1, the remaining experiments failed to reveal any disruptive influence of the beacon on learning based on the shape of the pool. Moreover, in Experiments 3-5 there was an indication that the beacon facilitated such learning. The results suggest that spatial learning based on the shape of a test environment may not take place in the same way as that based on more discrete landmarks.

  2. Molecular beacon-based half-adder and half-subtractor.

    PubMed

    Yang, Chia-Ning; Hsu, Chun-Yu; Chuang, Yu-Chung

    2012-01-01

    This work demonstrates two DNA-based logic circuits that behave as a half-adder and a half-subtractor. A half-adder is composed of an AND gate and an XOR gate, whereas a half-subtractor consists of an INH gate and an XOR gate. The proposed designs are inspired by molecular beacons.

  3. Genetic variation in BEACON influences quantitative variation in metabolic syndrome-related phenotypes.

    PubMed

    Jowett, Jeremy B; Elliott, Kate S; Curran, Joanne E; Hunt, Nicola; Walder, Ken R; Collier, Greg R; Zimmet, Paul Z; Blangero, John

    2004-09-01

    The BEACON gene (also known as UBL5) was identified as differentially expressed between lean and obese Psammomys obesus, a polygenic animal model of obesity, type 2 diabetes, and dyslipidemia. The human homologue of BEACON is located on chromosome 19p, a region likely to contain genes affecting metabolic syndrome-related quantitative traits as established by linkage studies. To assess whether the human BEACON gene may be involved in influencing these traits, we exhaustively analyzed the complete gene for genetic variation in 40 unrelated individuals and identified four variants (three novel). The two more common variants were tested for association with a number of quantitative metabolic syndrome-related traits in two large cohorts of unrelated individuals. Significant associations were found between these variants and fat mass (P = 0.026), percentage of fat (P = 0.001), and waist-to-hip ratio (P = 0.031). The same variants were also associated with total cholesterol (P = 0.024), LDL cholesterol (P = 0.019), triglycerides (P = 0.006), and postglucose load insulin levels (P = 0.018). Multivariate analysis of these correlated phenotypes also yielded a highly significant association (P = 0.0004), suggesting that BEACON may influence phenotypic variation in metabolic syndrome-related traits.

  4. The road to excellence: Magnet designation, the Beacon Award, and primary nursing.

    PubMed

    Mondino, Karen

    2005-06-01

    The potential to have a unit based on excellence is within every manager's reach. The ability to submit for the Beacon Award and Magnet hospital designation are two avenues to fulfill that potential. Successes from University of California Davis Medical Center are shared in this article in the hope of inspiring other managers and their staff.

  5. Chimeric RNA-DNA molecular beacon assay for ribonuclease H activity.

    PubMed

    Rizzo, J; Gifford, L K; Zhang, X; Gewirtz, A M; Lu, P

    2002-08-01

    Current methods to detect and assay ribonuclease H (RNase H) activity are indirect and time-consuming. Here we introduce a direct and sensitive method, based on the fluorescence quenching mechanism of molecular beacons, to assay RNA cleavage in RNA:DNA hybrids. An RNA-DNA chimeric beacon assay for RNase H enzymatic activity was developed. The substrate is a single-stranded RNA-DNA chimeric oligonucleotide labeled with a 5'-fluorescein and a 3'-DABCYL. The fluorophore (fluorescein) of the probe is held in close proximity to the quencher (DABCYL) by the RNA:DNA stem-loop structure. When the RNA sequence of the RNA:DNA hybrid stem is cleaved, the fluorophore is separated from the quencher and fluorescence can be detected as a function of time. Chimeric beacons with different stem lengths and sequences have been surveyed for this assay with E. coli RNase H. We found that the beacon kinetic parameters are in qualitative agreement with previously reported values using more cumbersome assays. This method permits real-time detection of RNase H activity and a convenient approach to RNase H kinetic and mechanistic study.

  6. Single-cell detection of mRNA expression using nanofountain-probe electroporated molecular beacons.

    PubMed

    Giraldo-Vela, Juan P; Kang, Wonmo; McNaughton, Rebecca L; Zhang, Xuemei; Wile, Brian M; Tsourkas, Andrew; Bao, Gang; Espinosa, Horacio D

    2015-05-01

    New techniques for single-cell analysis enable new discoveries in gene expression and systems biology. Time-dependent measurements on individual cells are necessary, yet the common single-cell analysis techniques used today require lysing the cell, suspending the cell, or long incubation times for transfection, thereby interfering with the ability to track an individual cell over time. Here a method for detecting mRNA expression in live single cells using molecular beacons that are transfected into single cells by means of nanofountain probe electroporation (NFP-E) is presented. Molecular beacons are oligonucleotides that emit fluorescence upon binding to an mRNA target, rendering them useful for spatial and temporal studies of live cells. The NFP-E is used to transfect a DNA-based beacon that detects glyceraldehyde 3-phosphate dehydrogenase and an RNA-based beacon that detects a sequence cloned in the green fluorescence protein mRNA. It is shown that imaging analysis of transfection and mRNA detection can be performed within seconds after electroporation and without disturbing adhered cells. In addition, it is shown that time-dependent detection of mRNA expression is feasible by transfecting the same single cell at different time points. This technique will be particularly useful for studies of cell differentiation, where several measurements of mRNA expression are required over time.

  7. Rapid identification of Candida dubliniensis using a species-specific molecular beacon.

    PubMed

    Park, S; Wong, M; Marras, S A; Cross, E W; Kiehn, T E; Chaturvedi, V; Tyagi, S; Perlin, D S

    2000-08-01

    Candida dubliniensis is an opportunistic fungal pathogen that has been linked to oral candidiasis in AIDS patients, although it has recently been isolated from other body sites. DNA sequence analysis of the internal transcribed spacer 2 (ITS2) region of rRNA genes from reference Candida strains was used to develop molecular beacon probes for rapid, high-fidelity identification of C. dubliniensis as well as C. albicans. Molecular beacons are small nucleic acid hairpin probes that brightly fluoresce when they are bound to their targets and have a significant advantage over conventional nucleic acid probes because they exhibit a higher degree of specificity with better signal-to-noise ratios. When applied to an unknown collection of 23 strains that largely contained C. albicans and a smaller amount of C. dubliniensis, the species-specific probes were 100% accurate in identifying both species following PCR amplification of the ITS2 region. The results obtained with the molecular beacons were independently verified by random amplified polymorphic DNA analysis-based genotyping and by restriction enzyme analysis with enzymes BsmAI and NspBII, which cleave recognition sequences within the ITS2 regions of C. dubliniensis and C. albicans, respectively. Molecular beacons are promising new probes for the rapid detection of Candida species.

  8. Light-inducible molecular beacons for spatio-temporally highly defined activation.

    PubMed

    Rinne, Jennifer S; Kaminski, Tim P; Kubitscheck, Ulrich; Heckel, Alexander

    2013-06-14

    We have developed a new molecular beacon design that requires an additional UV pulse for fluorescence activation. This improves the signal-to-noise ratio tremendously compared to previous approaches and allows for a precise control of the time point and location of RNA labelling.

  9. NLS peptide conjugated molecular beacons for visualizing nuclear RNA in living cells.

    PubMed

    Nitin, Nitin; Bao, Gang

    2008-11-19

    Imaging the expression and localization of RNAs in live-cell nucleus can provide important information on RNA synthesis, processing, and transport. Here, we report the development of a bifunctional molecular beacon (NLS-MB) composed of a single nuclear localization sequence (NLS) peptide conjugated to a molecular beacon for efficient delivery and imaging of endogenous RNAs in the nuclei of living cells. We characterized the NLS-MBs by comparing their signal-to-noise ratios with unmodified molecular beacons and determined their efficiency of nuclear import. We demonstrated the specificity and sensitivity of the method by observing in living cells the localization and colocalization of small nuclear RNAs (snRNA) U1 and U2 at discrete foci in the nucleoplasm, and the localization of small nucleolar RNA U3 in the nucleolus. These snRNAs were chosen because of their essential roles in RNA biogenesis. The results were validated using in situ hybridization as positive control and random beacons as negative control. This novel approach may be applied to imaging other nuclear RNAs and pre-mRNAs in living cells.

  10. Spectroscopic features of dual fluorescence/luminescence resonance energy-transfer molecular beacons.

    PubMed

    Tsourkas, Andrew; Behlke, Mark A; Xu, Yangqing; Bao, Gang

    2003-08-01

    Molecular beacons have the potential to become a powerful tool in gene detection and quantification in living cells. Here we report a novel dual molecular beacons approach to reduce false-positive signals in detecting target nucleic acids in homogeneous assays. A pair of molecular beacons, each containing a fluorescence quencher and a reporter fluorophore, one with a donor and a second with an acceptor fluorophore, hybridize to adjacent regions on the same target resulting in fluorescence resonance energy transfer (FRET). The detection of a FRET signal leads to a substantially increased signal-to-background ratio compared with that seen in single molecular beacon assays and enables discrimination between fluorescence due to specific probe/target hybridization and a variety of possible false-positive events. Further, when a lanthanide chelate is used as a donor in a dual-probe assay, extremely high signal-to-background ratios can be achieved owing to the long lifetime and sharp emission peaks of the donor and the time-gated detection of acceptor fluorescence emission. These new approaches allow for the ultrasensitive detection of target molecules in a way that could be readily applied to real-time imaging of gene expression in living cells.

  11. Impacts of Fog Characteristics, Forward Illumination, and Warning Beacon Intensity Distribution on Roadway Hazard Visibility

    PubMed Central

    2016-01-01

    Warning beacons are critical for the safety of transportation, construction, and utility workers. These devices need to produce sufficient luminous intensity to be visible without creating glare to drivers. Published standards for the photometric performance of warning beacons do not address their performance in conditions of reduced visibility such as fog. Under such conditions light emitted in directions other than toward approaching drivers can create scattered light that makes workers and other hazards less visible. Simulations of visibility of hazards under varying conditions of fog density, forward vehicle lighting, warning beacon luminous intensity, and intensity distribution were performed to assess their impacts on visual performance by drivers. Each of these factors can influence the ability of drivers to detect and identify workers and hazards along the roadway in work zones. Based on the results, it would be reasonable to specify maximum limits on the luminous intensity of warning beacons in directions that are unlikely to be seen by drivers along the roadway, limits which are not included in published performance specifications. PMID:27314058

  12. Locked nucleic acid based beacons for surface interaction studies and biosensor development

    PubMed Central

    Martinez, Karen; Estevez, M.-Carmen; Wu, Yanrong; Phillips, Joseph A.; Medley, Colin D.; Tan, Weihong

    2011-01-01

    DNA sensors and microarrays permit fast, simple and real-time detection of nucleic acids through the design and use of increasingly sensitive, selective and robust molecular probes. Specifically, molecular beacons (MBs) have been employed for this purpose; however, their potential in the development of solid-surface-based biosensors has not been fully realized. This is mainly a consequence of the beacon’s poor stability due to the hairpin structure once immobilized onto a solid surface, commonly resulting in a low signal enhancement. Here, we report the design of a new MB that overcomes some of the limitations of MBs for surface immobilization. Essentially, this new design adds locked nucleic acid bases (LNAs) to the beacon structure, resulting in a LNA molecular beacon (LMB) with robust stability after surface immobilization. To test the efficacy of LMBs against that of regular molecular beacons (RMBs), the properties of selectivity, sensitivity, thermal stability, hybridization kinetics and robustness for the detection of target sequences were compared and evaluated. A 25-fold enhancement was achieved for the LMB on surface with detection limits reaching the low nanomolar range. In addition, the LMB-based biosensor was shown to possess better stability, reproducibility, selectivity and robustness when compared to the RMB. Therefore, as an alternative to conventional DNA and as a prospective tool for use in both DNA microarrays and biosensors, these results demonstrate the potential of the locked nucleic acid bases for nucleic acid design for surface immobilization. PMID:19351140

  13. A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs

    PubMed Central

    Mo, Yuanfu; Yu, Dexin; Song, Jun; Zheng, Kun; Guo, Yajuan

    2015-01-01

    In a vehicular ad hoc network (VANET), the periodic exchange of single-hop status information broadcasts (beacon frames) produces channel loading, which causes channel congestion and induces information conflict problems. To guarantee fairness in beacon transmissions from each node and maximum network connectivity, adjustment of the beacon transmission power is an effective method for reducing and preventing channel congestion. In this study, the primary factors that influence wireless channel loading are selected to construct the KF-BCLF, which is a channel load forecasting algorithm based on a recursive Kalman filter and employs multiple regression equation. By pre-adjusting the transmission power based on the forecasted channel load, the channel load was kept within a predefined range; therefore, channel congestion was prevented. Based on this method, the CLF-BTPC, which is a transmission power control algorithm, is proposed. To verify KF-BCLF algorithm, a traffic survey method that involved the collection of floating car data along a major traffic road in Changchun City is employed. By comparing this forecast with the measured channel loads, the proposed KF-BCLF algorithm was proven to be effective. In addition, the CLF-BTPC algorithm is verified by simulating a section of eight-lane highway and a signal-controlled urban intersection. The results of the two verification process indicate that this distributed CLF-BTPC algorithm can effectively control channel load, prevent channel congestion, and enhance the stability and robustness of wireless beacon transmission in a vehicular network. PMID:26571042

  14. Toxoplasma gondii DNA detection with a magnetic molecular beacon probe

    NASA Astrophysics Data System (ADS)

    Xu, Shichao; Yao, Cuicui; Wei, Shuoming; Zhang, Jimei; Dai, Zhao; Zheng, Guo; Sun, Bo; Han, Qing; Hu, Fei; Zhou, Hongming

    2008-12-01

    Toxoplasma Gondii infection is widespread in humans worldwide and reported infection rates range from 3%-70%, depending on the populations or geographic areas, and it has been recognized as a potential food safety hazard in our daily life. A magnetic molecular beacon probe (mMBP), based on theory of fluorescence resonance energy transfer (FRET), was currently reported to detect Toxoplasma Gondii DNA. Nano-sized Fe3O4 were primarily prepared by coprecipitation method in aqueous phase with NaOH as precipitator, and was used as magnetic core. The qualified coreshell magnetic quantum dots (mQDs), i.e. CdTe(symbol)Fe3O4, were then achieved by layer-by-layer method when mol ratio of Fe3O4/CdTe is 1/3, pH at 6.0, 30 °C, and reactant solution was refluxed for 30 min, the size of mQDs were determined to be 12-15 nm via transmission electron microscopy (TEM). Over 70% overlap between emission spectrum of mQDs and absorbance spectrum of BHQ-2 was observed, this result suggests the synthesized mQDs and BHQ-2 can be utilized as energy donor and energy acceptor, respectively. The sensing probe was fabricated and a stem-loop Toxoplasma Gondii DNA oligonucleotide was labeled with mQDs at the 5' end and BHQ-2 at 3' end, respectively. Target Toxoplasma gondii DNA was detected under conditions of 37 °C, hybridization for 2h, at pH8.0 in Tris-HCl buffer. About 30% recovery of fluorescence intensity was observed via fluorescence spectrum (FS) after the Toxoplasma gondii DNA was added, which suggested that the Toxoplasma Gondii DNA was successfully detected. Specificity investigation of the mMBP indicated that relative low recovery of fluorescence intensity was obtained when the target DNA with one-base pair mismatch was added, this result indicated the high specificity of the sensing probe. Our research simultaneously indicated that mMBP can be conveniently separated from the unhybridized stem-loop DNA and target DNA, which will be meaningful in DNA sensing and purification process.

  15. Rationally designed molecular beacons for bioanalytical and biomedical applications.

    PubMed

    Zheng, Jing; Yang, Ronghua; Shi, Muling; Wu, Cuichen; Fang, Xiaohong; Li, Yinhui; Li, Jishan; Tan, Weihong

    2015-05-21

    Nucleic acids hold promise as biomolecules for future applications in biomedicine and biotechnology. Their well-defined structures and compositions afford unique chemical properties and biological functions. Moreover, the specificity of hydrogen-bonded Watson-Crick interactions allows the construction of nucleic acid sequences with multiple functions. In particular, the development of nucleic acid probes as essential molecular engineering tools will make a significant contribution to advancements in biosensing, bioimaging and therapy. The molecular beacon (MB), first conceptualized by Tyagi and Kramer in 1996, is an excellent example of a double-stranded nucleic acid (dsDNA) probe. Although inactive in the absence of a target, dsDNA probes can report the presence of a specific target through hybridization or a specific recognition-triggered change in conformation. MB probes are typically fluorescently labeled oligonucleotides that range from 25 to 35 nucleotides (nt) in length, and their structure can be divided into three components: stem, loop and reporter. The intrinsic merit of MBs depends on predictable design, reproducibility of synthesis, simplicity of modification, and built-in signal transduction. Using resonance energy transfer (RET) for signal transduction, MBs are further endowed with increased sensitivity, rapid response and universality, making them ideal for chemical sensing, environmental monitoring and biological imaging, in contrast to other nucleic acid probes. Furthermore, integrating MBs with targeting ligands or molecular drugs can substantially support their in vivo applications in theranositics. In this review, we survey advances in bioanalytical and biomedical applications of rationally designed MBs, as they have evolved through the collaborative efforts of many researchers. We first discuss improvements to the three components of MBs: stem, loop and reporter. The current applications of MBs in biosensing, bioimaging and therapy will then

  16. Concept for a laser guide beacon Shack-Hartmann wave-front sensor with dynamically steered subapertures.

    PubMed

    Baranec, Christoph J; Bauman, Brian J; Lloyd-Hart, Michael

    2005-04-01

    We describe an innovative implementation of the Shack-Hartmann wave-front sensor that is designed to correct the perspective elongation of a laser guide beacon in adaptive optics. Subapertures are defined by the segments of a deformable mirror rather than by a conventional lenslet array. A bias tilt on each segment separates the beacon images on the sensor's detector. One removes the perspective elongation by dynamically driving each segment with a predetermined open-loop signal that would, in the absence of atmospheric wave-front aberration, keep the corresponding beacon image centered on the subaperture's optical axis.

  17. Double-hairpin molecular-beacon-based amplification detection for gene diagnosis linked to cancer.

    PubMed

    Xu, Huo; Zhang, Rongbo; Li, Feng; Zhou, Yingying; Peng, Ting; Wang, Xuedong; Shen, Zhifa

    2016-09-01

    A powerful double-hairpin molecular beacon (DHMB) was developed for cancer-related KRAS gene detection based on the one-to-two stoichiometry. During target DNA detection, DHMB can execute signal transduction even if no any exogenous element is involved. Unlike the conventional molecular beacon based on the one-to-one interaction, one target DNA not only hybridizes with one DHMB and opens its hairpin but also promotes the interaction between two DHMBs, causing the separation of two fluorophores from quenchers. This leads to an enhanced fluorescence signal. As a result, the target KRAS gene is able to be detected within a wide dynamic range from 0.05 to 200 nM with the detection limit of 50 pM, indicating a dramatic improvement compared with traditional molecular beacons. Moreover, the point mutations existing in target DNAs can be easily screened. The potential application for target species in real samples was indicated by the analysis of PCR amplicons of DNAs from the DNA extracted from SW620 cell. Besides becoming a promising candidate probe for molecular biology research and clinical diagnosis of genetic diseases, the DHMB is expected to provide a significant insight into the design of DNA probe-based homogenous sensing systems. Graphical Abstract A powerful double-hairpin molecular beacon (DHMB) was developed for cancer-related gene KRAS detection based on the one-to-two stoichiometry. Without the help of any exogenous probe, the point mutation is easily screened, and the target DNA can be quantified down to 50 pM, indicating a dramatic improvement compared with traditional molecular beacons. PMID:27422649

  18. Double-hairpin molecular-beacon-based amplification detection for gene diagnosis linked to cancer.

    PubMed

    Xu, Huo; Zhang, Rongbo; Li, Feng; Zhou, Yingying; Peng, Ting; Wang, Xuedong; Shen, Zhifa

    2016-09-01

    A powerful double-hairpin molecular beacon (DHMB) was developed for cancer-related KRAS gene detection based on the one-to-two stoichiometry. During target DNA detection, DHMB can execute signal transduction even if no any exogenous element is involved. Unlike the conventional molecular beacon based on the one-to-one interaction, one target DNA not only hybridizes with one DHMB and opens its hairpin but also promotes the interaction between two DHMBs, causing the separation of two fluorophores from quenchers. This leads to an enhanced fluorescence signal. As a result, the target KRAS gene is able to be detected within a wide dynamic range from 0.05 to 200 nM with the detection limit of 50 pM, indicating a dramatic improvement compared with traditional molecular beacons. Moreover, the point mutations existing in target DNAs can be easily screened. The potential application for target species in real samples was indicated by the analysis of PCR amplicons of DNAs from the DNA extracted from SW620 cell. Besides becoming a promising candidate probe for molecular biology research and clinical diagnosis of genetic diseases, the DHMB is expected to provide a significant insight into the design of DNA probe-based homogenous sensing systems. Graphical Abstract A powerful double-hairpin molecular beacon (DHMB) was developed for cancer-related gene KRAS detection based on the one-to-two stoichiometry. Without the help of any exogenous probe, the point mutation is easily screened, and the target DNA can be quantified down to 50 pM, indicating a dramatic improvement compared with traditional molecular beacons.

  19. Low cost high efficiency GaAs monolithic RF module for SARSAT distress beacons

    NASA Technical Reports Server (NTRS)

    Petersen, W. C.; Siu, D. P.; Cook, H. F.

    1991-01-01

    Low cost high performance (5 Watts output) 406 MHz beacons are urgently needed to realize the maximum utilization of the Search and Rescue Satellite-Aided Tracking (SARSAT) system spearheaded in the U.S. by NASA. Although current technology can produce beacons meeting the output power requirement, power consumption is high due to the low efficiency of available transmitters. Field performance is currently unsatisfactory due to the lack of safe and reliable high density batteries capable of operation at -40 C. Low cost production is also a crucial but elusive requirement for the ultimate wide scale utilization of this system. Microwave Monolithics Incorporated (MMInc.) has proposed to make both the technical and cost goals for the SARSAT beacon attainable by developing a monolithic GaAs chip set for the RF module. This chip set consists of a high efficiency power amplifier and a bi-phase modulator. In addition to implementing the RF module in Monolithic Microwave Integrated Circuit (MMIC) form to minimize ultimate production costs, the power amplifier has a power-added efficiency nearly twice that attained with current commercial technology. A distress beacon built using this RF module chip set will be significantly smaller in size and lighter in weight due to a smaller battery requirement, since the 406 MHz signal source and the digital controller have far lower power consumption compared to the 5 watt power amplifier. All the program tasks have been successfully completed. The GaAs MMIC RF module chip set has been designed to be compatible with the present 406 MHz signal source and digital controller. A complete high performance low cost SARSAT beacon can be realized with only additional minor iteration and systems integration.

  20. First Results for the TBB/CERTO Beacon Experiment on FORMOSAT- 3/COSMIC

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Siefring, C. L.; Garner, T. W.; Gaussiran, T. L.; Secan, J.; Smith, F.; Groves, K.

    2006-12-01

    The Coherent Electromagnetic Radio Tomography (CERTO) instrument is a Tri-Band Beacon (TBB) that radiates unmodulated radio frequency carriers at 150.012, 400.032, and 1066.752 MHz. As part of the FORMOSAT-3 program, the six Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) satellites were launched in April 2006 with the TBB instrument along with a GPS occultation receiver (GOX) and a Tiny Ionospheric Photometer (TIP). Each of these instruments is capable of measuring integrated plasma density parameters for the F-region. The COSMIC satellites were initially deployed into 520 km orbits with 72 degrees inclination all in the same orbit plane. Each satellite will be boosted up to 800 km altitude with month-long time delays to allow separation of the orbits into six planes. Ground based receivers in Alaska, Virginia, Peru, and Kwajalein have recorded the radio beacon signals from the COSMIC CERTO beacons to determine the signal and antenna pattern specifications and to provide preliminary measurements of ionosphere TEC and radio scintillations. Because of power limitations and radio interference, TBB/CERTO frequency operations must be scheduled for passes over ground receivers. The ionospheric radio beacon data has been primarily obtained using the VHF and UHF CERTO frequencies. These data are complementary to ground based incoherent scatter radar (ISR) and ionosonde measurements as well as the GOX and TIP sensors on the satellites. Both tomography and inverse diffraction algorithms have been used to convert the radio beacon measurements into estimates of ionospheric electron density structures.

  1. Surveillance technology for HIV-1 subtype C in Ethiopia: an env-based NASBA molecular beacon assay to discriminate between subcluster C and C'.

    PubMed

    Ayele, Workenesh; Baar, Michel P de; Goudsmit, Jaap; Kliphuis, Aletta; Tilahun, Tesfaye; Dorigo-Zetsma, Wendelien; Wolday, Dawit; Abebe, Almaz; Mengistu, Yohannes; Pollakis, Georgios

    2005-12-01

    Forty-nine samples with known C2V3 sequences were used for the evaluation of an env-based molecular beacon assay to distinguish between the two genetic subclusters C and C' which characterize the HIV-1 epidemic in Ethiopia. Two subcluster C and two subcluster C' beacons targeting two different loci in the C2V3 region were developed. Using a three beacon-based (2C and 1C'=C prime), isothermal amplification assay, concordance with DNA sequencing was achieved for 43 (87.8%) samples. Sensitivity was 81.8% and specificity 97.4% for subcluster C beacons. For the subcluster C' beacon, a sensitivity of 97% and a specificity of 87.5% was achieved. Five samples were ambiguous by sequencing of which two samples were subcluster C' by the beacon assay and one subcluster C. Two of the samples remained ambiguous with different beacon-pair combinations as well. From samples with a clear C or C' phylogeny by sequencing, three were undetected by the first-line beacon genotyping assay. Genotype ambiguity was resolved in the three samples using beacon pair combinations restricted to each targeted locus. The beacons were evaluated further in a panel including all HIV-1 subtypes. Four of five subtype C isolates were identified correctly, and no cross-reactivity was observed with other subtypes.

  2. Improving the detectability of oxygen saturation level targets for preterm neonates: A laboratory test of tremolo and beacon sonifications.

    PubMed

    Deschamps, Marie-Lys; Sanderson, Penelope; Hinckfuss, Kelly; Browning, Caitlin; Loeb, Robert G; Liley, Helen; Liu, David

    2016-09-01

    Recent guidelines recommend oxygen saturation (SpO2) levels of 90%-95% for preterm neonates on supplemental oxygen but it is difficult to discern such levels with current pulse oximetry sonifications. We tested (1) whether adding levels of tremolo to a conventional log-linear pulse oximetry sonification would improve identification of SpO2 ranges, and (2) whether adding a beacon reference tone to conventional pulse oximetry confuses listeners about the direction of change. Participants using the Tremolo (94%) or Beacon (81%) sonifications identified SpO2 range significantly more accurately than participants using the LogLinear sonification (52%). The Beacon sonification did not confuse participants about direction of change. The Tremolo sonification may have advantages over the Beacon sonification for monitoring SpO2 of preterm neonates, but both must be further tested with clinicians in clinically representative scenarios, and with different levels of ambient noise and distractions. PMID:27184324

  3. Performance of a demonstration system for simultaneous laser beacon tracking and low data rate optical communications with multiple platforms

    NASA Astrophysics Data System (ADS)

    Short, R. C.; Cosgrove, M.; Clark, D. L.; Oleski, P.

    1991-06-01

    The ability of a system based on a high-speed area array detector to simultaneously track and receive data from multiple low-power optical communication beacons is demonstrated. Specifically, the MOCTR POC system has achieved tracking precision of order 0.1 pixel with 2.7 picowatts, the minimum beacon power for the assumed system architecture; a data rate of 1 kbps with BER of order 1 to 10 x 10 exp -5, readily correctable with forward error correction; tracking and communication with simulated maximum earth background in the detector FOV; and simultaneous tracking of asynchronously modulated beacons. Areas needed to be addressed before an operational system can be implemented include reduction in size, weight and power, the demonstration of independent acquisition of multiple beacons, and the implementation of a full tracking algorithm in firmware.

  4. Conceptual development of a ground-based radio-beacon navigation system for use on the surface of the moon

    NASA Technical Reports Server (NTRS)

    Beggins, Andrew J.; Canney, Lora M.; Dolezal, Anna Belle

    1988-01-01

    A spread-spectrum radio-beacon navigation system for use on the lunar surface is described. The subjects discussed are principle of operation and specifications to include power requirements, operating frequencies, weight, size, and range.

  5. Improving the detectability of oxygen saturation level targets for preterm neonates: A laboratory test of tremolo and beacon sonifications.

    PubMed

    Deschamps, Marie-Lys; Sanderson, Penelope; Hinckfuss, Kelly; Browning, Caitlin; Loeb, Robert G; Liley, Helen; Liu, David

    2016-09-01

    Recent guidelines recommend oxygen saturation (SpO2) levels of 90%-95% for preterm neonates on supplemental oxygen but it is difficult to discern such levels with current pulse oximetry sonifications. We tested (1) whether adding levels of tremolo to a conventional log-linear pulse oximetry sonification would improve identification of SpO2 ranges, and (2) whether adding a beacon reference tone to conventional pulse oximetry confuses listeners about the direction of change. Participants using the Tremolo (94%) or Beacon (81%) sonifications identified SpO2 range significantly more accurately than participants using the LogLinear sonification (52%). The Beacon sonification did not confuse participants about direction of change. The Tremolo sonification may have advantages over the Beacon sonification for monitoring SpO2 of preterm neonates, but both must be further tested with clinicians in clinically representative scenarios, and with different levels of ambient noise and distractions.

  6. BEACON/MOD: a computer program for thermal-hydraulic analysis of nuclear reactor containments - user's manual

    SciTech Connect

    Broadus, C.R.; Doyle, R.J.; James, S.W.; Lime, J.F.; Mings, W.J.

    1980-04-01

    The BEACON code is a best-estimate, advanced containment code designed to perform a best-estimate analysis of the flow of a mixture of air, water, and steam in a nuclear reactor containment system under loss-of-coolant accident conditions. The code can simulate two-component, two-phase fluid flow in complex geometries using a combination of two-dimensional, one-dimensional, and lumped-parameter representations for the various parts of the system. The current version of BEACON, which is designated BEACON/MOD3, contains mass and heat transfer models for wall film and wall conduction. It is suitable for the evaluation of short-term transients in dry-containment systems. This manual describes the models employed in BEACON/MOD3 and specifies code implementation requirements. It provides application information for input data preparation and for output data interpretation.

  7. Label-free hybridization detection of a single nucleotide mismatch by immobilization of molecular beacons on an agarose film.

    PubMed

    Wang, Hong; Li, Jiong; Liu, Heping; Liu, Quanjun; Mei, Qian; Wang, Yijin; Zhu, Jijun; He, Nongyue; Lu, Zuhong

    2002-06-15

    We developed a new technique to immobilize a set of molecular beacons on an agarose film-coated slide and found that it has the ability to identify a single nucleotide difference in label-free DNA targets. The annealing properties, specificity and hybridization dynamics of the present technique were compared with those of the conventional technique that directly immobilizes molecular beacons on a planar glass slide. It is demonstrated that the molecular beacon array on an agarose film has high quench efficiency, an excellent discrimination ratio for single nucleotide mismatches and a short detection time. We hypothesize that such a low fluorescence background and high specificity molecular beacon array will find practical applications in label-free, high-throughput mutation analysis and disease diagnosis.

  8. Real-time nucleic acid sequence-based amplification using molecular beacons for detection of enterovirus RNA in clinical specimens.

    PubMed

    Landry, Marie L; Garner, Robin; Ferguson, David

    2005-07-01

    Real-time nucleic acid sequence-based amplification (NASBA) using molecular beacon technology (NASBA-beacon) was compared to standard NASBA with postamplification hybridization using electrochemiluminescently labeled probes (NASBA-ECL) for detection of enteroviruses (EV) in 133 cerebrospinal fluid and 27 stool samples. NASBA-ECL and NASBA-beacon were similar in sensitivity, detecting 55 (100%) and 52 (94.5%) EV-positive samples, respectively. There were no false positives. Both NASBA assays were significantly more sensitive than culture. Real-time NASBA-beacon reagents and equipment rental were more expensive than those for NASBA-ECL; however, time to result was shortened by 1.5 h, hands-on time was reduced by 25 min, and the assay was much simpler for technologists to learn and perform.

  9. Assistant DNA recycling with nicking endonuclease and molecular beacon for signal amplification using a target-complementary arched structure.

    PubMed

    Gao, Fenglei; Lei, Jianping; Ju, Huangxian

    2013-05-11

    A simple and universal method for ultrasensitive "signal on" detection of DNA was developed with a target-complementary arched structure to release assistant DNA, which was recycled with nicking endonuclease to amplify the detectable fluorescent signal of molecular beacons.

  10. A simple "molecular beacon"-based fluorescent sensing strategy for sensitive and selective detection of mercury (II).

    PubMed

    Xu, Huifeng; Zhu, Xi; Ye, Hongzhi; Yu, Lishuang; Liu, Xianxiang; Chen, Guonan

    2011-11-28

    A novel fluorescent sensor for the detection of Hg(2+) in aqueous media was developed. The method takes advantages of the highly selective thymine-Hg(2+)-thymine coordination and the sensitive "signal-on" structure-switching molecular beacon.

  11. Increasing the sensitivity and single-base mismatch selectivity of the molecular beacon using graphene oxide as the "nanoquencher".

    PubMed

    Lu, Chun-Hua; Li, Juan; Liu, Jing-Jing; Yang, Huang-Hao; Chen, Xi; Chen, Guo-Nan

    2010-04-26

    Here, we report a novel, highly sensitive, selective and economical molecular beacon using graphene oxide as the "nanoquencher". This novel molecular beacon system contains a hairpin-structured fluorophore-labeled oligonucleotide and a graphene oxide sheet. The strong interaction between hairpin-structured oligonucleotide and graphene oxide keep them in close proximity, facilitating the fluorescence quenching of the fluorophore by graphene oxide. In the presence of a complementary target DNA, the binding between hairpin-structured oligonucleotide and target DNA will disturb the interaction between hairpin-structured oligonucleotide and graphene oxide, and release the oligonucleotide from graphene oxide, resulting in restoration of fluorophore fluorescence. In the present study, we show that this novel graphene oxide quenched molecular beacon can be used to detect target DNA with higher sensitivity and single-base mismatch selectivity compared to the conventional molecular beacon.

  12. Triplex molecular beacons for sensitive recognition of melamine based on abasic-site-containing DNA and fluorescent silver nanoclusters.

    PubMed

    Wang, Ya; Sun, Qianqian; Zhu, Linling; Zhang, Junying; Wang, Fengyang; Lu, Linlin; Yu, Haijun; Xu, Zhiai; Zhang, Wen

    2015-05-01

    A melamine aptamer derived from an abasic-site-containing triplex molecular beacon (tMB) was designed and developed for sensitive recognition of melamine by integrating tMBs and fluorescent silver nanoclusters (Ag NCs).

  13. The 406 MHz ELT/EPIRBs. [Emergency Locator Transmitters/Emergency Position Indicating Radio Beacons (ELT/EPIRB)

    NASA Technical Reports Server (NTRS)

    Flatow, F. S.; Gal, C.; Hayes, E. J.

    1984-01-01

    Specifications for the COSPAS/SARSAT beacons are presented and related design considerations are discussed. Critical design aspects having significant impact on cost and performance are highlighted. Among these is the oscillator, whose frequency drift specifications require stabilization by ovens or digital control. Design options are presented and their impact on cost and performance assessed. Beacon designs developed to meet COSPAS/SARSAT specifications are shown.

  14. Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Wintucky, Edwin G.

    2014-01-01

    The design and test results of a novel waveguide multimode directional coupler for a CW millimeter-wave satellite beacon source are presented. The coupler separates the second harmonic power from the fundamental output power of a traveling-wave tube amplifier. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37 to 42 GHz) and VW-band (71 to 76 GHz) satellite-to-ground signals.

  15. Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Wintucky, Edwin G.

    2014-01-01

    This paper presents the design and test results of a CW millimeter-wave satellite beacon source, based on the second harmonic from a traveling-wave tube amplifier and utilizes a novel waveguide multimode directional coupler. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37-42 GHz) and V/W-band (71- 76 GHz) satellite-to-ground signals.

  16. Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Wintucky, Edwin G.

    2014-01-01

    This paper presents the design and test results of a CW millimeter-wave satellite beacon source, based on the second harmonic from a traveling-wave tube amplifier and utilizes a novel waveguide multimode directional coupler. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37 to 42 GHz) and V/W-band (71 to 76 GHz) satellite-to-ground signals.

  17. Detection of SNP-containing human DNA sequences using a split sensor with a universal molecular beacon reporter.

    PubMed

    Gerasimova, Yulia V; Ballantyne, Jack; Kolpashchikov, Dmitry M

    2013-01-01

    Hybridization-based techniques have been extensively employed for the analysis of specific DNA/RNA sequences. Herein, we describe highly specific inexpensive smart hybridization-based sensor that takes advantage of a universal molecular beacon probe as a fluorescent reporter. The sensor has a straightforward design, and demonstrates improved selectivity and specificity of nucleic acid recognition. It is cost-efficient since it utilizes the same molecular beacon probe for the analysis of many nucleic acid sequences.

  18. The Chemistry of Ethene in the Storm Beacon Region on Saturn

    NASA Astrophysics Data System (ADS)

    Armstrong, Eleanor S.; Moses, Julianne I.; Fletcher, Leigh N.; Irwin, Patrick G.; Hesman, Brigette E.; Romani , Paul N.

    2014-11-01

    The immense tropospheric storm that erupted in Saturn’s northern spring hemisphere was first observed on 5th December 2010 (Sanchez-Lavega et al. 2011, Nature 475, 71), and displayed typical storm signatures such as lightning activity and clouds (e.g., Fischer et al. 2011, Nature 475, 75). However, Cassini/CIRS also observed an unexpected stratospheric response consisting of elevated temperatures and molecular abundances, which has come to be known as the ‘beacon’ region (Fletcher et al. 2011, Science 332, 1413). Most significantly the abundance of ethene (C2H4; also called ethylene) was observed to have increased by a factor of ~100 in the stratospheric beacon region in May 2011, compared with photochemical models and observations from the same latitude before the storm (Hesman et al. 2012, ApJ. 760, 24). Our project seeks to replicate the abundances of C2H4 and other hydrocarbons observed in the Cassini/CIRS beacon data through photochemical modeling. The KINETICS code (Allen et al. 1981, JGR 86, 3617) has been used to solve the 1-D continuity equations for stratospheric hydrocarbon and oxygen species, assuming the "Model C" chemical reaction list of Moses et al. (2005; JGR 110, E08001), and time-variable beacon temperatures, retrieved from the Cassini/CIRS data by Fletcher et al. (2012; Icarus 221, 560). The models predict a greatly increased C2H4 abundance in the high-temperature beacon regions, with a distinct mixing-ratio peak near 1 mbar. This increase is the result of a highly temperature-dependent reaction that produces C2H4. No such increases were seen in the model for other major hydrocarbons such as C2H2 and C2H6. The predicted C2H4 emission from our models still falls short of reproducing the observed beacon emission for May 2011, but the multiplicative factor required to scale the model profile to reproduce the CIRS emission has been reduced to a factor of ~5 from the previous factor of ~100. The important chemical production and loss mechanisms

  19. Cleavable DNA-protein hybrid molecular beacon: A novel efficient signal translator for sensitive fluorescence anisotropy bioassay.

    PubMed

    Hu, Pan; Yang, Bin

    2016-01-15

    Due to its unique features such as high sensitivity, homogeneous format, and independence on fluorescent intensity, fluorescence anisotropy (FA) assay has become a hotspot of study in oligonucleotide-based bioassays. However, until now most FA probes require carefully customized structure designs, and thus are neither generalizable for different sensing systems nor effective to obtain sufficient signal response. To address this issue, a cleavable DNA-protein hybrid molecular beacon was successfully engineered for signal amplified FA bioassay, via combining the unique stable structure of molecular beacon and the large molecular mass of streptavidin. Compared with single DNA strand probe or conventional molecular beacon, the DNA-protein hybrid molecular beacon exhibited a much higher FA value, which was potential to obtain high signal-background ratio in sensing process. As proof-of-principle, this novel DNA-protein hybrid molecular beacon was further applied for FA bioassay using DNAzyme-Pb(2+) as a model sensing system. This FA assay approach could selectively detect as low as 0.5nM Pb(2+) in buffer solution, and also be successful for real samples analysis with good recovery values. Compatible with most of oligonucleotide probes' designs and enzyme-based signal amplification strategies, the molecular beacon can serve as a novel signal translator to expand the application prospect of FA technology in various bioassays. PMID:26592607

  20. Cleavable DNA-protein hybrid molecular beacon: A novel efficient signal translator for sensitive fluorescence anisotropy bioassay.

    PubMed

    Hu, Pan; Yang, Bin

    2016-01-15

    Due to its unique features such as high sensitivity, homogeneous format, and independence on fluorescent intensity, fluorescence anisotropy (FA) assay has become a hotspot of study in oligonucleotide-based bioassays. However, until now most FA probes require carefully customized structure designs, and thus are neither generalizable for different sensing systems nor effective to obtain sufficient signal response. To address this issue, a cleavable DNA-protein hybrid molecular beacon was successfully engineered for signal amplified FA bioassay, via combining the unique stable structure of molecular beacon and the large molecular mass of streptavidin. Compared with single DNA strand probe or conventional molecular beacon, the DNA-protein hybrid molecular beacon exhibited a much higher FA value, which was potential to obtain high signal-background ratio in sensing process. As proof-of-principle, this novel DNA-protein hybrid molecular beacon was further applied for FA bioassay using DNAzyme-Pb(2+) as a model sensing system. This FA assay approach could selectively detect as low as 0.5nM Pb(2+) in buffer solution, and also be successful for real samples analysis with good recovery values. Compatible with most of oligonucleotide probes' designs and enzyme-based signal amplification strategies, the molecular beacon can serve as a novel signal translator to expand the application prospect of FA technology in various bioassays.

  1. Live-cell characterization and analysis of a clinical isolate of bovine respiratory syncytial virus, using molecular beacons.

    PubMed

    Santangelo, Philip; Nitin, Nitin; LaConte, Leslie; Woolums, Amelia; Bao, Gang

    2006-01-01

    Understanding viral pathogenesis is critical for prevention of outbreaks, development of antiviral drugs, and biodefense. Here, we utilize molecular beacons to directly detect the viral genome and characterize a clinical isolate of bovine respiratory syncytial virus (bRSV) in living cells. Molecular beacons are dual-labeled, hairpin oligonucleotide probes with a reporter fluorophore at one end and a quencher at the other; they are designed to fluoresce only when hybridizing to a complementary target. By imaging the fluorescence signal of molecular beacons, the spread of bRSV was monitored for 7 days with a signal-to-noise ratio of 50 to 200, and the measured time course of infection was quantified with a mathematical model for viral growth. We found that molecular beacon signal could be detected in single living cells infected with a viral titer of 2 x 10(3.6) 50% tissue culture infective doses/ml diluted 1,000 fold, demonstrating high detection sensitivity. Low background in uninfected cells and simultaneous staining of fixed cells with molecular beacons and antibodies showed high detection specificity. Furthermore, using confocal microscopy to image the viral genome in live, infected cells, we observed a connected, highly three-dimensional, amorphous inclusion body structure not seen in fixed cells. Taken together, the use of molecular beacons for active virus imaging provides a powerful tool for rapid viral infection detection, the characterization of RNA viruses, and the design of new antiviral drugs.

  2. Target accessibility and signal specificity in live-cell detection of BMP-4 mRNA using molecular beacons.

    PubMed

    Rhee, Won Jong; Santangelo, Philip J; Jo, Hanjoong; Bao, Gang

    2008-03-01

    The ability to visualize mRNA in single living cells and monitor in real-time the changes of mRNA level and localization can provide unprecedented opportunities for biological and disease studies. However, the mRNA detection specificity and sensitivity are critically dependent on the selection of target sequences and their accessibility. We carried out an extensive study of the target accessibility of BMP-4 mRNA using 10 different designs of molecular beacons (MBs), and identified the optimal beacon design. Specifically, for MB design 1 and 8 (MB1 and MB8), the fluorescent intensities from BMP-4 mRNA correlated well with the GFP signal after upregulating BMP-4 and co-expressing GFP using adenovirus, and the knockdown of BMP-4 mRNA using siRNA significantly reduced the beacon signals, demonstrating detection specificity. The beacon specificity was further confirmed using blocking RNA and in situ hybridization. We found that fluorescence signal from MBs depends critically on target sequences; the target sequences corresponding to siRNA sites may not be good sites for beacon-based mRNA detection, and vice versa. Possible beacon design rules are identified and approaches for enhancing target accessibility are discussed. This has significant implications to MB design for live cell mRNA detection.

  3. Significant enhancement of fluorescence on hybridization of a molecular beacon to a target DNA in the presence of a site-specific DNA nickase.

    PubMed

    Zheleznaya, Ludmila A; Kopein, Damir S; Rogulin, Evgeniy A; Gubanov, Sergey I; Matvienko, Nikolay I

    2006-01-01

    We have developed a simple isothermal (55 degrees C) reaction that permits detection of DNA targets using only two components: a molecular beacon and a site-specific DNA nickase without deoxyribonucleotide triphosphates and primers. The loop sequence of the molecular beacon should contain a DNA nickase recognition site. The nickase-molecular beacon (NMB) combination permits a 100-fold increase in fluorescent signal. The applications of the NMB assay for enhancement of fluorescent signal in some isothermal methods are discussed.

  4. Topical MMP beacon enabled fluorescence-guided resection of oral carcinoma.

    PubMed

    Burgess, Laura; Chen, Juan; Wolter, Nikolaus E; Wilson, Brian; Zheng, Gang

    2016-03-01

    Each year almost 300,000 individuals worldwide are diagnosed with oral cancer, more than 90% of these being oral carcinoma [N. Engl. J. Med.328, 1841993]. Surgical resection is the standard of care, but accurate delineation of the tumor boundaries is challenging, resulting in either under-resection with risk of local recurrence or over-resection with increased functional loss and negative impact on quality of life. This study evaluates, in two pre-clinical in vivo tumor models, the potential of fluorescence-guided resection using molecular beacons activated by metalloproteinases, which are frequently upregulated in human oral cancer. In both models there was rapid (<15 min) beacon activation upon local application, allowing clear fluoresecence imaging in vivo and confirmed by ex vivo fluorescence microscopy and HPLC, with minimal activation in normal oral tissues. Although the tissue penetration was limited using topical application, these findings support further development of this approach towards translation to first-in-human trials.

  5. Evaluation design and technical assistance opportunities: early findings from the Beacon Community Program evaluation teams.

    PubMed

    Rein, Alison; Kennedy, Hilary; DeCoudres, Ben; Singer Cohen, Rebecca; Sabharwal, Raj; Fairbrother, Gerry

    2012-01-01

    The Beacon Community Cooperative Agreement Program is funding 17 communities to build and strengthen their health information technology (IT) capabilities to enhance care coordination, improve patient and population health, and reduce or restrain costs. Based on the experiences and evidence generated by these communities, the program hopes to illustrate the possibilities of leveraging health IT to achieve desired goals. Doing so requires rigorous evaluation work, which is the subject of this issue brief. Based on semistructured interviews with representatives from each Beacon Community, the brief outlines various study designs, evaluation approaches, outcome measures, and data sources in use. It also identifies some common challenges, including establishing governance models, determining baseline measures, and assessing impact in a relatively constrained timeframe. Technical assistance in disseminating and publishing findings and assessing return on investments will be offered in the coming year.

  6. A Telomerase-Specific Doxorubicin-Releasing Molecular Beacon for Cancer Theranostics.

    PubMed

    Ma, Yi; Wang, Zhaohui; Zhang, Min; Han, Zhihao; Chen, Dan; Zhu, Qiuyun; Gao, Weidong; Qian, Zhiyu; Gu, Yueqing

    2016-03-01

    A molecular beacon-based drug delivery system was designed for both detection of telomerase activity in living cells and telomerase-triggered drug release for precise cancer treatment. This system is composed of a gold nanoparticle core densely packed with FITC-labeled hairpin DNA sequences hybridized with telomerase primers. Molecules of the anticancer drug doxorubicin were intercalated into the stem region of the DNA sequence. The presence of telomerase will elongate the primers, leading to inner chain substitution followed by the release of the FITC fluorescence and the trapped doxorubicin. This molecular beacon could specifically distinguish tumor cells and normal cells based on telomerase activity, precisely release doxorubicin in response to telomerase activity in the tumor cells, and prevent toxicity to normal organs. PMID:26848056

  7. Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Wintucky, Edwin G.

    2016-01-01

    This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

  8. Design of a K/Q-Band Beacon Receiver for the Alphasat TDP#5 Experiment

    NASA Technical Reports Server (NTRS)

    Morse, Jacquelynne R.

    2014-01-01

    This paper describes the design and performance of a coherent KQ-band (2040 GHz) beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed at the Politecnico di Milano (POLIMI) for use in the Alphasat Technology Demonstration Payload 5 (TDP5) beacon experiment. The goal of this experiment is to characterize rain fade attenuation at 40 GHz to improve the performance of existing statistical rain attenuation models in the Q-band. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation. The receiver system has been characterized in the lab and demonstrates a system dynamic range performance of better than 58 dB at 1 Hz and better than 48 dB at 10 Hz rates.

  9. Mars approach navigation using Doppler and range measurements to surface beacons and orbiting spacecraft

    NASA Technical Reports Server (NTRS)

    Thurman, Sam W.; Estefan, Jeffrey A.

    1991-01-01

    Approximate analytical models are developed and used to construct an error covariance analysis for investigating the range of orbit determination accuracies which might be achieved for typical Mars approach trajectories. The sensitivity or orbit determination accuracy to beacon/orbiter position errors and to small spacecraft force modeling errors is also investigated. The results indicate that the orbit determination performance obtained from both Doppler and range data is a strong function of the inclination of the approach trajectory to the Martian equator, for surface beacons, and for orbiters, the inclination relative to the orbital plane. Large variations in performance were also observed for different approach velocity magnitudes; Doppler data in particular were found to perform poorly in determining the downtrack (along the direction of flight) component of spacecraft position. In addition, it was found that small spacecraft acceleration modeling errors can induce large errors in the Doppler-derived downtrack position estimate.

  10. Design of a K/Q-band Beacon Receiver for the Alphasat TDP#5 Experiment

    NASA Technical Reports Server (NTRS)

    Nessel, James A.; Zemba, Michael J.; Morse, Jacquelynne R.

    2014-01-01

    This paper describes the design and performance of a coherent K/Q-band (20/40GHz) beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed at the Politecnico di Milano (POLIMI) for use in the Alphasat Technology Demonstration Payload #5 (TDP#5) beacon experiment. The goal of this experiment is to characterize rain fade attenuation at 40GHz to improve the performance of existing statistical rain attenuation models in the Q-band. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation. The receiver system has been characterized in the lab and demonstrates a system dynamic range performance of better than 58dB at 1Hz and better than 48dB at 10Hz rates.

  11. Method and apparatus for a multibeam beacon laser assembly for optical communications

    NASA Technical Reports Server (NTRS)

    Biswas, Abhijit (Inventor); Sanji, Babak (Inventor); Wright, Malcolm W. (Inventor); Page, Norman Alan (Inventor)

    2005-01-01

    An optical beacon is comprised of a telescope having a primary focal plane or Coud? focal plane, a plurality of fiber coupled laser sources for generating a plurality of beams, a collimator for collimating the plurality of beams, and optics for combining and focusing the plurality of collimated beams onto the primary or Coud? focal plane of the telescope. The telescope propagates the optical beacon, which is arranged into a ring of incoherent plurality of collimated beams. The apparatus further comprises fiber splitters coupled to each laser source to provide at least eight beams from at least four laser sources. The optics comprises a prism assembly, a combiner lens, a focusing lens and a field lens for focusing the plurality of collimated beams onto the primary focal plane or Coud? focal plane of the telescope.

  12. Automated Internet-Based Control of Spacecraft Groundstations: Beacon-Based Health Monitoring Concept

    NASA Technical Reports Server (NTRS)

    Cantwell, Brian; Twiggs, Robert; Swartwout, Michael

    1997-01-01

    This report serves as an update about the activities of Stanford University's Space Systems Development Laboratory (SSDL) in their beacon-based health monitoring experiment. Section 1 describes the goals of the project and the organization of the team. Section 2 provides an overview of the major components of the system, describing the general approach of automated health monitoring and the beacon signal relay. It also provides background about the SAPPHIRE spacecraft and ASSET operations system, which will be used for the experiment. Specific details about implementation and status of each element of the experiment are found in Section 3. Section 4 describes the experiment and future work, and references are contained in Section 5.

  13. A Telomerase-Specific Doxorubicin-Releasing Molecular Beacon for Cancer Theranostics.

    PubMed

    Ma, Yi; Wang, Zhaohui; Zhang, Min; Han, Zhihao; Chen, Dan; Zhu, Qiuyun; Gao, Weidong; Qian, Zhiyu; Gu, Yueqing

    2016-03-01

    A molecular beacon-based drug delivery system was designed for both detection of telomerase activity in living cells and telomerase-triggered drug release for precise cancer treatment. This system is composed of a gold nanoparticle core densely packed with FITC-labeled hairpin DNA sequences hybridized with telomerase primers. Molecules of the anticancer drug doxorubicin were intercalated into the stem region of the DNA sequence. The presence of telomerase will elongate the primers, leading to inner chain substitution followed by the release of the FITC fluorescence and the trapped doxorubicin. This molecular beacon could specifically distinguish tumor cells and normal cells based on telomerase activity, precisely release doxorubicin in response to telomerase activity in the tumor cells, and prevent toxicity to normal organs.

  14. Steranes and triterpanes in the Beacon Supergroup samples from southern Victoria Land in Antarctica

    SciTech Connect

    Matsumoto, Genki I.; Watanuki, Kunihiko ); Machihara, Tsutomu ); Suzuki, Noriyuki ); Funaki, Minoru )

    1987-10-01

    Steranes and triterpanes in Beacon Supergroup samples (sedimentary rock and silicified wood) from Allan Hills and Carapace Nunatak of southern Victoria Land in Antarctica were studied to elucidate sources of organic materials, sedimentary paleoenvironment and thermal history after deposition. Relative abundances of C{sub 27}, C{sub 28} and C{sub 29} steranes and visual kerogen results of Beacon Supergroup samples from Allan Hills imply that organic materials in the sedimentary paleoenvironments are contributed mainly by vascular plants with some influence of microorganisms, while those of the Carapace Nunatak sample may be largely due to fern spores. The pristane/phytane and pristane/heptadecane ratios of the samples were generally close to unity and between 0.50 and 0.99, respectively, suggesting that the sedimentary paleoenvironment was shallow lacustrine with alternating oxic and anoxic conditions.

  15. Real-time monitoring of nucleic acid ligation in homogenous solutions using molecular beacons.

    PubMed

    Tang, Zhiwen; Wang, Kemin; Tan, Weihong; Li, Jun; Liu, Lingfeng; Guo, Qiuping; Meng, Xiangxian; Ma, Changbei; Huang, Shasheng

    2003-12-01

    Nucleic acids ligation is a vital process in the repair, replication and recombination of nucleic acids. Traditionally, it is assayed by denatured gel electrophoresis and autoradiography, which are not sensitive, and are complex and discontinuous. Here we report a new approach for ligation monitoring using molecular beacon DNA probes. The molecular beacon, designed in such a way that its sequence is complementary with the product of the ligation process, is used to monitor the nucleic acid ligation in a homogeneous solution and in real-time. Our method is fast and simple. We are able to study nucleic acids ligation kinetics conveniently and to determine the activity of DNA ligase accurately. We have studied different factors that influence DNA ligation catalyzed by T4 DNA ligase. The major advantages of our method are its ultrasensitivity, excellent specificity, convenience and real-time monitoring in homogeneous solution. This method will be widely useful for studying nucleic acids ligation process and other nucleic acid interactions.

  16. Signal control by self-assembly of fluorophores in a molecular beacon--a model study.

    PubMed

    Biner, Sarah M; Kummer, Dominic; Malinovskii, Vladimir L; Häner, Robert

    2011-04-21

    Pyrene excimer fluorescence is efficiently regulated through formation of π-stacked aggregates between dialkynylpyrene (Y) and perylenediimide (E) residues located in the stem region of a molecular beacon (MB). The building blocks form organized, multichromophoric complexes in the native form. Hybridization to the target results in a conformational reorganization of the chromophores. The nature of the aggregates was investigated by changing the number of chromophores and natural base pairs in the beacon stem. The formation of different types of complexes (EYEY→YEY→EY) is revealed by characteristic spectroscopic changes. The data show that signal control is an intrinsic property of the interacting chromophores. The directed assembly of non-nucleosidic chromophores can be used for the generation of an on/off switch of a fluorescence signal. The concept may find applications in various types of light-based input/output systems.

  17. Detection of DNA with Catalytic Beacons Based on Peroxidase-oxidase Oscillating Reaction.

    PubMed

    Zeng, Jinhong; Liu, Qiong; Xu, Huibi; Wang, Hongmei; Wang, Jun; Cai, Ruxiu

    2005-01-01

    This paper aims at investigating a new method for the detection of DNA with catalytic beacons based on peroxidase-oxidase (PO) oscillation and analytic pulse perturbation technique. Two DNAzymes were constructed by the binding of specific DNA sequence with hemin or by the hybridization of target DNA with the catalytic beacon. Both DNAzymes possessed peroxidase-like activity and perturb the PO oscillator reaction when they were added into the oscillation system. The period and amplitude of oscillation increased significantly by both DNAzymes, which implied the decrease in the average rate of consumption of oxygen in solution, i.e., the decrease of the average rate of NADH oxidation. The results provide a new sensitive method for DNA detection and molecular recognition.

  18. Design and validation of two optical beacons for guidewire localization in breast-conserving surgery.

    PubMed

    Wilson, Rebecca Anne; McAleavey, Stephen A; Schiffhauer, Linda M; Zavislan, James

    2013-06-10

    Stereotactically placed guidewires are used for indicating the location of a nonpalpable carcinoma in breast-conserving surgery. Pathologists use the end of the embedded guidewire to guide sectioning during intraoperative margin assessment, but they do not currently have a tool to indicate the location of the guidewire end for informed sectioning. We present analysis and experimental testing of two optical methods for localizing the end of an embedded fiber-optic guidewire: the first uses irradiance emitted from the fiber to indicate the location of the guidewire end, while the second system uses the fiber optic to create a photoacoustic pulse for localization. Both systems locate the end of the guidewire within ±5 mm, which ensures that the lesion of interest is bisected during sectioning. The accuracy of the irradiance-based beacon is influenced by standard margin paints, so the photoacoustic beacon proved more useful under current tissue-handling protocols.

  19. Molecular beacon probes combined with amplification by NASBA enable homogeneous, real-time detection of RNA.

    PubMed

    Leone, G; van Schijndel, H; van Gemen, B; Kramer, F R; Schoen, C D

    1998-05-01

    Molecular beacon probes can be employed in a NASBA amplicon detection system to generate a specific fluorescent signal concomitantly with amplification. A molecular beacon, designed to hybridize within the target sequence, was introduced into NASBA reactions that amplify the genomic RNA of potato leafroll virus (PLRV). During amplification, the probe anneals to the antisense RNA amplicon generated by NASBA, producing a specific fluorescent signal that can be monitored in real-time. The assay is rapid, sensitive and specific. As RNA amplification and detection can be carried out in unopened vessels, it minimizes the risk of carry-over contaminations. Robustness has been verified on real-world samples. This homogeneous assay, called AmpliDet RNA, is a significant improvement over current detection methods for NASBA amplicons and is suitable for one-tube applications ranging from high-throughput diagnostics to in vivo studies of biological activities.

  20. Bifunctional colorimetric oligonucleotide probe based on a G-quadruplex DNAzyme molecular beacon.

    PubMed

    Zhang, Libing; Zhu, Jinbo; Li, Tao; Wang, Erkang

    2011-12-01

    A label-free bifunctional colorimetric oligonucleotide probe for DNA and protein detection has been developed on the basis of a novel catalytic molecular beacon consisting of two hairpin structures and a split G-quadruplex DNAzyme in the middle. The two loops of this molecular beacon consist of thrombin aptamer sequence and the complementary sequence of target DNA, which are utilized to sense single-stranded DNA and thrombin. The G-quadruplex DNAzyme can effectively catalyze the H(2)O(2)-mediated oxidation of 3,3',5,5'-tetramethylbenzidine sulfate to generate colorimetric signal. Upon addition of the target, the DNA or protein combines with one loop of the hairpin structures, and meanwhile drives the middle G-quadruplex DNAzyme to dissociate. This results in a decrease of catalytic activity, enabling the separate analysis of DNA and thrombin.

  1. Molecular beacon sequence analysis for detecting drug resistance in Mycobacterium tuberculosis.

    PubMed

    Piatek, A S; Tyagi, S; Pol, A C; Telenti, A; Miller, L P; Kramer, F R; Alland, D

    1998-04-01

    We developed a new approach to DNA sequence analysis that uses fluorogenic reporter molecules--molecular beacons--and demonstrated their ability to discriminate alleles in real-time PCR assays of genomic DNA. A set of overlapping molecular beacons was used to analyze an 81-bp region of the Mycobacterium tuberculosis rpoB gene for mutations that confer resistance to the antibiotic rifampin. In a blinded study of 52 rifampin-resistant and 23 rifampin-susceptible clinical isolates, this method correctly detected mutations in all of the resistant strains and in none of the susceptible strains. The assay was carried out entirely in sealed PCR tubes and was simple to perform and interpret. This approach can be used to analyze any DNA sequence of moderate length with single base pair accuracy.

  2. PNA Molecular Beacons Assembled by Post-Synthetic Click Chemistry Functionalization.

    PubMed

    Wang, Xiaoxiao; Hudson, Robert H E

    2015-10-12

    To avoid the tedious synthesis of functionalized peptide nucleic acid (PNA) monomers for probe development, we proposed a simple approach to modify PNA oligomers by post-synthetic on-resin click chemistry. PNA molecular beacons (MBs) were prepared by incorporation of azide-containing monomers into the oligomer by automatic solid-phase peptide synthesis and subsequent derivatization with pyrene moieties by copper-catalyzed azide-alkyne cycloaddition. Two pyrene-based quencher-free PNA molecular beacons, a stemless MB and one possessing a stem-loop structure, targeting a portion of the cystic fibrosis gene, were successfully synthesized by using this method. Fluorescence studies showed that the stem-loop MB exhibited better discrimination of changes in excimer/monomer ratios as compared to the stemless MB construct.

  3. Beacon-like immunoreactivity in the hypothalamus of Sprague-Dawley rats.

    PubMed

    Brailoiu, G Cristina; Dun, Siok L; Yang, Jun; Chang, Jaw Kang; Castellino, Sonya; Dun, Nae J

    2002-01-14

    Distribution of the novel peptide beacon in the hypothalamus of Sprague-Dawley rats was examined by immunohistochemical methods. Beacon-immunoreactive (irBC) neurons were found in the paraventricular, supraoptic, and accessory neurosecretory nuclei, and intensely labeled fibers in the median eminence and infundibulo-pituitary stalk. Scattered cells and/or fibers were noted in the suprachiasmatic nucleus, arcuate nucleus, retrochiasmatic area, lateral and medial preoptic area, as well as anterior and lateral hypothalamic area. The wide distribution of irBC in the hypothalamus of Sprague-Dawley rats suggests that the peptide may influence, in addition to a proposed role in feeding, a multitude of biological activities associated with the hypothalamic-pituitary axis.

  4. The study of the effect of solar eclipses on the ionosphere based on satellite beacon observations

    NASA Astrophysics Data System (ADS)

    Cohen, E. A.

    1984-06-01

    The ionospheric effect of a solar eclipse was first noticed in 1927 during an English eclipse. In studies of the effects of solar eclipses on the ionosphere by ionosondes during the next 30 years, the obtained results were difficult to interpret. Results obtained after the introduction of additional techniques indicate that the redistribution of ionization due to temperature changes is important, as is recombination. More recently, a more detailed study of the eclipse effects throughout the ionosphere was made possible as a result of the addition of the satellite beacon observations. The present investigation provides a review of the study of eclipse effects on the ionosphere based on satellite beacon observations. Attention is given to early observations, and total and partial solar eclipses over North America, Africa, Australia, and India.

  5. Increased dose near the skin due to electromagnetic surface beacon transponder.

    PubMed

    Ahn, Kang-Hyun; Manger, Ryan; Halpern, Howard J; Aydogan, Bulent

    2015-01-01

    The purpose of this study was to evaluate the increased dose near the skin from an electromagnetic surface beacon transponder, which is used for localization and tracking organ motion. The bolus effect due to the copper coil surface beacon was evaluated with radiographic film measurements and Monte Carlo simulations. Various beam incidence angles were evaluated for both 6 MV and 18 MV experimentally. We performed simulations using a general-purpose Monte Carlo code MCNPX (Monte Carlo N-Particle) to supplement the experimental data. We modeled the surface beacon geometry using the actual mass of the glass vial and copper coil placed in its L-shaped polyethylene terephthalate tubing casing. Film dosimetry measured factors of 2.2 and 3.0 enhancement in the surface dose for normally incident 6 MV and 18 MV beams, respectively. Although surface dose further increased with incidence angle, the relative contribution from the bolus effect was reduced at the oblique incidence. The enhancement factors were 1.5 and 1.8 for 6 MV and 18 MV, respectively, at an incidence angle of 60°. Monte Carlo simulation confirmed the experimental results and indicated that the epidermal skin dose can reach approximately 50% of the dose at dmax at normal incidence. The overall effect could be acceptable considering the skin dose enhancement is confined to a small area (~ 1 cm2), and can be further reduced by using an opposite beam technique. Further clinical studies are justified in order to study the dosimetric benefit versus possible cosmetic effects of the surface beacon. One such clinical situation would be intact breast radiation therapy, especially large-breasted women. PMID:26103472

  6. Increased dose near the skin due to electromagnetic surface beacon transponder.

    PubMed

    Ahn, Kang-Hyun; Manger, Ryan; Halpern, Howard J; Aydogan, Bulent

    2015-05-08

    The purpose of this study was to evaluate the increased dose near the skin from an electromagnetic surface beacon transponder, which is used for localization and tracking organ motion. The bolus effect due to the copper coil surface beacon was evaluated with radiographic film measurements and Monte Carlo simulations. Various beam incidence angles were evaluated for both 6 MV and 18 MV experimentally. We performed simulations using a general-purpose Monte Carlo code MCNPX (Monte Carlo N-Particle) to supplement the experimental data. We modeled the surface beacon geometry using the actual mass of the glass vial and copper coil placed in its L-shaped polyethylene terephthalate tubing casing. Film dosimetry measured factors of 2.2 and 3.0 enhancement in the surface dose for normally incident 6 MV and 18 MV beams, respectively. Although surface dose further increased with incidence angle, the relative contribution from the bolus effect was reduced at the oblique incidence. The enhancement factors were 1.5 and 1.8 for 6 MV and 18 MV, respectively, at an incidence angle of 60°. Monte Carlo simulation confirmed the experimental results and indicated that the epidermal skin dose can reach approximately 50% of the dose at dmax at normal incidence. The overall effect could be acceptable considering the skin dose enhancement is confined to a small area (~ 1 cm2), and can be further reduced by using an opposite beam technique. Further clinical studies are justified in order to study the dosimetric benefit versus possible cosmetic effects of the surface beacon. One such clinical situation would be intact breast radiation therapy, especially large-breasted women.

  7. Development of BEACON technology. Topical report: tandem reactor testing of hydrogen catalyst

    SciTech Connect

    Not Available

    1984-06-01

    The BEACON process involves the catalytic deposition of a highly reactive form of carbon from a gas stream which contains carbon monoxide. The carbon-depleted gas is combusted with air to produce power, and the carbon is reacted with steam to produce methane or hydrogen. Both the methane production and hydrogen production processes from low Btu gases have been developed successfully through bench-scale under a Cooperative Agreement between the US Department of Energy and TRW, Inc. Bench-scale development of the methane process was completed during the second quarter of 1983. Also catalyst selection testing (screening tests) for hydrogen manufacturing was completed at the same time and the results reported in a Topical Report dated October 1983. This document summarizes the data generated at bench-scale on the production of hydrogen from low Btu gas. Bench-scale development of the BEACON hydrogen process was concluded with the completion of Task 3. The objective of Task 3 was to qualify through bench-scale a BEACON-type catalyst for the production of hydrogen from low Btu gases. Catalyst No. 11, a modified SNG BEACON catalyst which proved highly selective to hydrogen production during laboratory scale screening tests was subjected to a total of 265 hours of steady state operation at three pressures (50, 75 and 100 psig) in the fluidized bed Tandem Reactor apparatus (bench-scale). The catalyst met all the requirements of stability and selectivity cited above. Carbon deposition and carbon steaming to hydrogen took place at near equilibrium yields, methane suppression was greater than 80% at all pressures, and there was no significant build-up of inactive carbon residue on the catalyst. 19 figs., 5 tabs.

  8. Developing children's palliative care in Africa through beacon centres: lessons learnt.

    PubMed

    Downing, Julia D; Marston, Joan; Selwyn, Casey; Ross-Gakava, Laura

    2013-02-18

    Much progress has been made in the provision of palliative care across sub-Saharan Africa, however much still remains to be done, particularly in the area of children's palliative care (CPC). The Beacon Centres programme was set up in 2009, aimed at improving access to CPC in South Africa, Uganda and Tanzania through more and better-trained health professionals and CPC clinical services of a high standard. Having identified sites in each country to develop into CPC Beacon Centres, Navigators were identified who would be the 'champions' for CPC in those sites and lead a programme of training, mentorship and support. Five navigators (2 in Uganda and Tanzania and 1 in South Africa) were trained between September and December 2009. Following this they undertook CPC needs assessments at the 3 centres and set up and delivered a six-month CPC training programme, providing mentorship and support to students to enable them to integrate CPC into their workplaces. To date, 188 participants have commenced the six-month course, with 80 having completed it. CPC has been integrated into the activities of the centres and a CPC virtual resource centre set up in South Africa. The achievements from the Beacon project have been great and the work of the navigators immense, but as in all projects it has not been without its challenges. Lessons learnt include issues around: the focus of the project; the length and nature of the training; assessment; accreditation; the choice of navigators; mentoring; administrative support; co-ordination; the choice of project sites; and the integration of CPC into services. The need for CPC is not going to go away and it is therefore important that models of scaling-up are found that are not only practical, feasible, affordable and sustainable, but that focus on the outcome of improved CPC for all those who need it. It is hoped that the lessons shared from the Beacon Project will help in developing and implementing such models.

  9. Lessons Learned During Implementation and Early Operations of the DS1 Beacon Monitor Experiment

    NASA Technical Reports Server (NTRS)

    Sherwood, Rob; Wyatt, Jay; Hotz, Henry; Schlutsmeyer, Alan; Sue, Miles

    1998-01-01

    A new approach to mission operations will be flight validated on NASA's New Millennium Program Deep Space One (DS1) mission which launched in October 1998. The Beacon Monitor Operations Technology is aimed at decreasing the total volume of downlinked engineering telemetry by reducing the frequency of downlink and the volume of data received per pass. Cost savings are achieved by reducing the amount of routine telemetry processing and analysis performed by ground staff. The technology is required for upcoming NASA missions to Pluto, Europa, and possibly some other missions. With beacon monitoring, the spacecraft will assess its own health and will transmit one of four beacon messages each representing a unique frequency tone to inform the ground how urgent it is to track the spacecraft for telemetry. If all conditions are nominal, the tone provides periodic assurance to ground personnel that the mission is proceeding as planned without having to receive and analyze downlinked telemetry. If there is a problem, the tone will indicate that tracking is required and the resulting telemetry will contain a concise summary of what has occurred since the last telemetry pass. The primary components of the technology are a tone monitoring technology, AI-based software for onboard engineering data summarization, and a ground response system. In addition, there is a ground visualization system for telemetry summaries. This paper includes a description of the Beacon monitor concept, the trade-offs with adapting that concept as a technology experiment, the current state of the resulting implementation on DS1, and our lessons learned during the initial checkout phase of the mission. Applicability to future missions is also included.

  10. Comparison of OLYMPUS beacon and radiometric attenuation measurements at Blacksburg, Virginia

    NASA Technical Reports Server (NTRS)

    Snider, J. B.; Jacobson, M. D.; Beeler, R. H.; Hazen, D. A.

    1991-01-01

    Measurements of attenuation of the 20 and 30 GHz beacons onboard the OLYMPUS satellite are compared to simultaneous observations of atmospheric attenuation by a multichannel microwave radiometer along the same path. Departures from high correlation between the two measurements are believed to be related to differences in antenna beamwidths. Mean equivalent zenith attenuations derived from the slant path data are compared to zenith observations made at previous locations.

  11. Quencher-free molecular beacon: Enhancement of the signal-to-background ratio with graphene oxide.

    PubMed

    Yi, Jeong Wu; Park, Jaesung; Singh, N Jiten; Lee, Il Joon; Kim, Kwang S; Kim, Byeang Hyean

    2011-01-15

    We report the highly improved version of quencher-free molecular beacon (QF-MB) system by using graphene oxide (GO) as an external quencher. This QF-MB/GO system provided a higher S/B ratio (31.0) relative to that (2.2) of the same system in the absence of GO, while retaining a high selectivity for fully matched over single-base-mismatched targets.

  12. Quencher-free molecular aptamer beacons (QF-MABs) for detection of ATP.

    PubMed

    Park, Jung Woo; Park, Yoojin; Kim, Byeang Hyean

    2015-10-15

    We have constructed a simple and efficient system-based on quencher-free molecular aptamer beacons (QF-MABs)-for probing ATP. In the absence of ATP, the fluorescence of a pyrene fluorophore on the loop position (15 nucleotides from the 5' end) of the optimal QF-MAB was quenched by the neighboring nucleobases; in its presence, fluorescence was recovered, due to a conformational change in the secondary structure of the QF-MAB.

  13. A highly discriminating quencher-free molecular beacon for probing DNA.

    PubMed

    Hwang, Gil Tae; Seo, Young Jun; Kim, Byeang Hyean

    2004-06-01

    We inserted a fluorene-labeled deoxyuridine derivative, synthesized using Sonogashira coupling, efficiently into the loop region of a DNA hairpin using phosphoramidite chemistry. This molecular beacon, which features no additional fluorescence quencher, discriminates between perfect and one-base-mismatched base pairing by changes in its fluorescence intensity. The discrimination factor is 14.7 for the recognition of a single (A/C) base mismatch.

  14. NSET molecular beacon analysis of hammerhead RNA substrate binding and catalysis.

    PubMed

    Jennings, T L; Schlatterer, J C; Singh, M P; Greenbaum, N L; Strouse, G F

    2006-07-01

    Nanometal surface energy transfer (NSET), which describes an energy transfer event from optically excited organic fluorophores to small metal nanoparticles, may be used as a molecular beacon/ruler similar to FRET, but with advantages over this classical technique. Here we use NSET to measure Mg(2+)-induced conformational changes for a hammerhead ribozyme and confirm these measurements using FRET. These optical experiments enhance our understanding of the different kinetic pathways for this ribozyme.

  15. The Beacon Project--a community-based health improvement project.

    PubMed

    Stuteley, Hazel

    2002-10-01

    Inequality and socioeconomic deprivation remain powerful determinants of the nation's health. The Beacon Project, led by two primary health care visitors, was initiated to tackle the rapidly declining health and social needs of a community in Cornwall, southwest England. Significant improvements in conditions and a general sense of wellbeing on the estate, together with the improvements in social outcomes was observed over a period of four years.

  16. A molecular peptide beacon for the ratiometric sensing of nucleic acids.

    PubMed

    Wu, Junchen; Zou, Ying; Li, Chunyan; Sicking, Wilhelm; Piantanida, Ivo; Yi, Tao; Schmuck, Carsten

    2012-02-01

    A pyrene-functionalized cationic oligopeptide 1 efficiently binds to double-stranded DNA, as shown by different spectrophotochemical studies. Upon binding, the conformation of 1 changes from a folded to an extended form, which leads to a distinct change in the fluorescence properties. Thus, 1 functions as a molecular peptide beacon, and as it is easily taken up by cells, 1 can also be used for imaging of nucleic acids within cells.

  17. The effects of a rectangular rapid-flashing beacon on vehicle speed.

    PubMed

    VanWagner, Michelle; Van Houten, Ron; Betts, Brian

    2011-01-01

    In 2008, nearly 31% of vehicle fatalities were related to failure to adhere to safe vehicle speeds (National Highway Traffic Safety Administration [NHTSA], 2009). The current study evaluated the effect of a rectangular rapid-flashing beacon (RRFB) triggered by excessive speed on vehicle speed using a combined alternating treatments and reversal design. The percentage of vehicles traveling above 41 mph (66 km per hour) decreased by 20%, and speed distributions showed a shift toward lower speeds during the RRFB condition.

  18. Star Death Beacon at the Edge of the Universe

    NASA Astrophysics Data System (ADS)

    2005-09-01

    short flashes of energetic gamma-rays lasting from less than a second to several minutes. They release a tremendous quantity of energy in this short time making them the most powerful events since the Big Bang. It is now widely accepted that the majority of the gamma-ray bursts signal the explosion of very massive, highly evolved stars that collapse into black holes. This discovery not only sets a new astronomical record, it is also fundamental to the understanding of the very young Universe. Being such powerful emitters, these Gamma Ray Bursts serve as useful beacons, enabling the study of the physical conditions that prevailed in the early Universe. Indeed, since GRBs are so luminous, they have the potential to outshine the most distant known galaxies and may thus probe the Universe at higher redshifts than currently known. And because Gamma-ray Burst are thought to be associated with the catastrophic death of very massive stars that collapse into black holes, the existence of such objects so early in the life of the Universe provide astronomers with important information to better understand its evolution. The Gamma-Ray Burst GRB050904 was first detected on September 4, 2005, by the NASA/ASI/PPARC Swift satellite, which is dedicated to the discovery of these powerful explosions. Immediately after this detection, astronomers in observatories worldwide tried to identify the source by searching for the afterglow in the visible and/or near-infrared, and study it. First observations by American astronomers with the Palomar Robotic 60-inch Telescope failed to find the source. This sets a very stringent limit: in the visible, the afterglow should thus be at least a million times fainter than the faintest object that can be seen with the unaided eye (magnitude 21). But observations by another team of American astronomers detected the source in the near-infrared J-band with a magnitude 17.5, i.e. at least 25 times brighter than in the visible. This was indicative of the fact

  19. A new electrochemically active-inactive switching aptamer molecular beacon to detect thrombin directly in solution.

    PubMed

    Cheng, Guifang; Shen, Bijun; Zhang, Fan; Wu, Jikui; Xu, Ying; He, Pingang; Fang, Yuzhi

    2010-06-15

    A new electrochemical aptamer molecular beacon (MB) was designed by the carminic acid (CA) covalently linking at the each end of a special single-stranded stem-loop shaped oligonucleotide and named as CAs-MB. CA is an electrochemically active molecule and two CA molecules at the ends of molecular beacon stem were closed enough to associate each other to be as CA dimer. The dimer was electrochemically inactive. It separated into two CA monomers and produced the electrochemical signal while CAs-MB combined with target. In this protocol, the detection strategy of CAs-MB for thrombin is based on electrochemical active-inactive switching between monomer and dimer forms of CA. In order to enhance the electrochemical signal, magnetic nanobeads (MNB) was applied by connecting CAs-MB with MNB through a duplex of DNA. With the magnetic enrichment, the detection limit for thrombin reached to 42.4 pM. The experiment results showed that this type of electrochemical active-inactive switching aptamer molecular beacon allowed the direct detection of target proteins in the solution with no requirement of removing uncombined CAs-MB. Besides, CAs-MB/MNB can be easily regenerated by using 2M NaCl solution to cleave the thrombin from the aptasensor. PMID:20378327

  20. Magnetic resonance beacon to detect intracellular microRNA during neurogenesis.

    PubMed

    Lee, Jonghwan; Jin, Yeon A; Ko, Hae Young; Lee, Yong Seung; Heo, Hyejung; Cho, Sujeong; Kim, Soonhag

    2015-02-01

    Magnetic resonance imaging (MRI) offers great spatial resolution for viewing deep tissues and anatomy. We developed a self-assembling signal-on magnetic fluorescence nanoparticle to visualize intracellular microRNAs (miRNAs or miRs) during neurogenesis using MRI. The self-assembling nanoparticle (miR124a MR beacon) was aggregated by the incubation of three different oligonucleotides: a 3' adaptor, a 5' adaptor, and a linker containing miR124a-binding sequences. The T2-weighted magnetic resonance (MR) signal of the self-assembled nanoparticle was quenched when miR124a was absent from test tubes or was minimally expressed in cells and tissues. When miR124a was present in test tubes or highly expressed in vitro and in vivo during P19 cell neurogenesis, it hybridized with the miR124a MR beacon, causing the linker to detach, resulting in increased signal-on MRI intensity. This MR beacon can be used as a new imaging probe to monitor the miRNA-mediated regulation of cellular processes.