WorldWideScience

Sample records for optimized interstellar beacons

  1. Messaging with Cost-Optimized Interstellar Beacons

    Science.gov (United States)

    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?"

  2. Messaging with Cost-Optimized Interstellar Beacons

    Science.gov (United States)

    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?"

  3. Optimalization of Beacon Selection for Localization in Wireless AD-HOC Networks

    Directory of Open Access Journals (Sweden)

    Martin Matula

    2008-01-01

    Full Text Available In this paper we engage in optimalization of convenient beacons for localization position of a node in the ad-hoc network. An algorithm designed by us localizes position of moving or static node by RSS (Received Signal Strength method and trilateration. At first, localization of unknown node runs by combination of all beacons. Than optimalizating algorithmreduces the number of beacons (and repeats localization, while only three left. Its reduction is based on highest levels of received signal strength. It is only when signals are from the nearest beacons. Position localizating exactness is statistically interpreted from all localization by beacons combination and its repeating.

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

    Science.gov (United States)

    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.

  5. A beacon configuration optimization method based on Fisher information for Mars atmospheric entry

    Science.gov (United States)

    Zhao, Zeduan; Yu, Zhengshi; Cui, Pingyuan

    2017-04-01

    The navigation capability of the proposed Mars network based entry navigation system is directly related to the beacon number and the relative configuration between the beacons and the entry vehicle. In this paper, a new beacon configuration optimization method is developed based on the Fisher information theory and this method is suitable for any number of visible beacons. The proposed method can be used for the navigation schemes based on range measurements provided by radio transceivers or other sensors for Mars entry. The observability of specific state is defined as its Fisher information based on the observation model. The overall navigation capability is improved by maximizing the minimum average Fisher information, even though the navigation system is not fully observed. In addition, when there is only one beacon capable of entry navigation and the observation information is relatively limited, the optimization method can be modulated to maximize the Fisher information of the specific state which may be preferred for the guidance and control system to improve its estimation accuracy. Finally, navigation scenarios consisted of 1-3 beacons are tested to validate the effectiveness of the developed optimization method. The extended Kalman filter (EKF) is employed to derive the state estimation error covariance. The results also show that the zero-Fisher information situation should be avoided, especially when the dynamic system is highly nonlinear and the states change dramatically.

  6. Lasers revisited - Their superior utility for interstellar beacons, communications, and travel

    Science.gov (United States)

    Rather, John D. G.

    1991-01-01

    This paper demonstrates reasons why research supporting SETI and Communication with Extraterrestrial Intelligence should be broadened to optical wavelengths rather than focusing almost entirely upon microwave wavelengths and technologies. New perceptions regarding the feasibility of laser technologies, along with reassessments of signal-to-noise considerations, show both the desirability and feasibility of optical interstellar transmissions, especially at IR and visible wavelengths. It is shown that utilization of the large bandwidths available at optical wavelengths greatly improves the possible use of such endeavors.

  7. Making it local: Beacon Communities use health information technology to optimize care management.

    Science.gov (United States)

    Allen, Amy; Des Jardins, Terrisca R; Heider, Arvela; Kanger, Chatrian R; Lobach, David F; McWilliams, Lee; Polello, Jennifer M; Rein, Alison L; Schachter, Abigail A; Singh, Ranjit; Sorondo, Barbara; Tulikangas, Megan C; Turske, Scott A

    2014-06-01

    Care management aims to provide cost-effective, coordinated, non-duplicative care to improve care quality, population health, and reduce costs. The 17 communities receiving funding from the Office of the National Coordinator for Health Information Technology through the Beacon Community Cooperative Agreement Program are leaders in building and strengthening their health information technology (health IT) infrastructure to provide more effective and efficient care management. This article profiles 6 Beacon Communities' health IT-enabled care management programs, highlighting the influence of local context on program strategy and design, and describing challenges, lessons learned, and policy implications for care delivery and payment reform. The unique needs (eg, disease burden, demographics), community partnerships, and existing resources and infrastructure all exerted significant influence on the overall priorities and design of each community's care management program. Though each Beacon Community needed to engage in a similar set of care management tasks--including patient identification, stratification, and prioritization; intervention; patient engagement; and evaluation--the contextual factors helped shape the specific strategies and tools used to carry out these tasks and achieve their objectives. Although providers across the country are striving to deliver standardized, high-quality care, the diverse contexts in which this care is delivered significantly influence the priorities, strategies, and design of community-based care management interventions. Gaps and challenges in implementing effective community-based care management programs include: optimizing allocation of care management services; lack of available technology tailored to care management needs; lack of standards and interoperability; integrating care management into care settings; evaluating impact; and funding and sustainability.

  8. Energy optimization for upstream data transfer in 802.15.4 beacon-enabled star formulation

    Science.gov (United States)

    Liu, Hua; Krishnamachari, Bhaskar

    2008-08-01

    Energy saving is one of the major concerns for low rate personal area networks. This paper models energy consumption for beacon-enabled time-slotted media accessing control cooperated with sleeping scheduling in a star network formulation for IEEE 802.15.4 standard. We investigate two different upstream (data transfer from devices to a network coordinator) strategies: a) tracking strategy: the devices wake up and check status (track the beacon) in each time slot; b) non-tracking strategy: nodes only wake-up upon data arriving and stay awake till data transmitted to the coordinator. We consider the tradeoff between energy cost and average data transmission delay for both strategies. Both scenarios are formulated as optimization problems and the optimal solutions are discussed. Our results show that different data arrival rate and system parameters (such as contention access period interval, upstream speed etc.) result in different strategies in terms of energy optimization with maximum delay constraints. Hence, according to different applications and system settings, different strategies might be chosen by each node to achieve energy optimization for both self-interested view and system view. We give the relation among the tunable parameters by formulas and plots to illustrate which strategy is better under corresponding parameters. There are two main points emphasized in our results with delay constraints: on one hand, when the system setting is fixed by coordinator, nodes in the network can intelligently change their strategies according to corresponding application data arrival rate; on the other hand, when the nodes' applications are known by the coordinator, the coordinator can tune the system parameters to achieve optimal system energy consumption.

  9. Optimal placement of range-only beacons for mobile robot localisation

    CSIR Research Space (South Africa)

    Burke, Michael G

    2011-11-01

    Full Text Available The ability of an agent to self-localise is crucial to any autonomous task where mobility is required. A common set of techniques solving the localisation problem involve the deployment of active beacons or landmarks, which eliminate problems...

  10. Molecular beacon sequence design algorithm.

    Science.gov (United States)

    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.

  11. Gold nanoparticle-based beacon to detect STAT5b mRNA expression in living cells: a case optimized by bioinformatics screen.

    Science.gov (United States)

    Deng, Dawei; Li, Yang; Xue, Jianpeng; Wang, Jie; Ai, Guanhua; Li, Xin; Gu, Yueqing

    2015-01-01

    Messenger RNA (mRNA), a single-strand ribonucleic acid with functional gene information is usually abnormally expressed in cancer cells and has become a promising biomarker for the study of tumor progress. Hairpin DNA-coated gold nanoparticle (hDAuNP) beacon containing a bare gold nanoparticle (AuNP) as fluorescence quencher and thiol-terminated fluorescently labeled stem-loop-stem oligonucleotide sequences attached by Au-S bond is currently a new nanoscale biodiagnostic platform capable of mRNA detection, in which the design of the loop region sequence is crucial for hybridizing with the target mRNA. Hence, in this study, to improve the sensitivity and selectivity of hDAuNP beacon simultaneously, the loop region of hairpin DNA was screened by bioinformatics strategy. Here, signal transducer and activator of transcription 5b (STAT5b) mRNA was selected and used as a practical example. The results from the combined characterizations using optical techniques, flow cytometry assay, and cell microscopic imaging showed that after optimization, the as-prepared hDAuNP beacon had higher selectivity and sensitivity for the detection of STAT5b mRNA in living cells, as compared with our previous beacon. Thus, the bioinformatics method may be a promising new strategy for assisting in the designing of the hDAuNP beacon, extending its application in the detection of mRNA expression and the resultant mRNA-based biological processes and disease pathogenesis.

  12. Gold nanoparticle-based beacon to detect STAT5b mRNA expression in living cells: a case optimized by bioinformatics screen

    Directory of Open Access Journals (Sweden)

    Deng D

    2015-04-01

    Full Text Available Dawei Deng,* Yang Li,* Jianpeng Xue, Jie Wang, Guanhua Ai, Xin Li, Yueqing GuDepartment of Biomedical Engineering, China Pharmaceutical University, Nanjing, People’s Republic of China*These authors contributed equally to this workAbstract: Messenger RNA (mRNA, a single-strand ribonucleic acid with functional gene information is usually abnormally expressed in cancer cells and has become a promising biomarker for the study of tumor progress. Hairpin DNA-coated gold nanoparticle (hDAuNP beacon containing a bare gold nanoparticle (AuNP as fluorescence quencher and thiol-terminated fluorescently labeled stem–loop–stem oligonucleotide sequences attached by Au–S bond is currently a new nanoscale biodiagnostic platform capable of mRNA detection, in which the design of the loop region sequence is crucial for hybridizing with the target mRNA. Hence, in this study, to improve the sensitivity and selectivity of hDAuNP beacon simultaneously, the loop region of hairpin DNA was screened by bioinformatics strategy. Here, signal transducer and activator of transcription 5b (STAT5b mRNA was selected and used as a practical example. The results from the combined characterizations using optical techniques, flow cytometry assay, and cell microscopic imaging showed that after optimization, the as-prepared hDAuNP beacon had higher selectivity and sensitivity for the detection of STAT5b mRNA in living cells, as compared with our previous beacon. Thus, the bioinformatics method may be a promising new strategy for assisting in the designing of the hDAuNP beacon, extending its application in the detection of mRNA expression and the resultant mRNA-based biological processes and disease pathogenesis.Keywords: molecular beacon, bioinformatics, gold nanoparticle, STAT5b mRNA, visual detection

  13. Designing reduced beacon trajectory for sensor localization

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Localization is one of the substantial issues in wireless sensor networks. The key problem for the mobile beacon localization is how to choose the appropriate beacon trajectory. However, little research has been done on it. In this paper, firstly,we deduce the number of positions for a beacon to send a packet according to the acreage of ROI (region of interest); and next we present a novel method based on virtual force to arrange the positions in arbitrary ROI; then we apply TSP (travelling salesman problem) algorithm to the positions sequence to obtain the optimal touring path, i.e. the reduced beacon trajectory. When a mobile beacon moves along the touring path, sending RF signals at every position, the sensors in ROI can work out their position with trilateration. Experimental results demonstrate that the localization method, based on the beacon reduced path, is efficient and has flexible accuracy.

  14. Adaptive polarimetric image representation for contrast optimization of a polarized beacon through fog

    CERN Document Server

    Panigrahi, Swapnesh; Alouini, Mehdi

    2015-01-01

    We present a contrast-maximizing optimal linear representation of polarimetric images obtained from a snapshot polarimetric camera for enhanced vision of a polarized light source in obscured weather conditions (fog, haze, cloud) over long distances (above 1 km). We quantitatively compare the gain in contrast obtained by different linear representations of the experimental polarimetric images taken during rapidly varying foggy conditions. It is shown that the adaptive image representation that depends on the correlation in background noise fluctuations in the two polarimetric images provides an optimal contrast enhancement over all weather conditions as opposed to a simple difference image which underperforms during low visibility conditions. Finally, we derive the analytic expression of the gain in contrast obtained with this optimal representation and show that the experimental results are in agreement with the assumed correlated Gaussian noise model.

  15. Special Stamps:Historical Relic Beacons

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In May 2002, the State Postal Bureau issued a set of five stamps picturing historical relic beacons. They are the Mao Beacon, the Jiangxinyu Twin Beacon, the Huaniaoshan Beacon, the Laotieshan Beacon, and

  16. Auditory evacuation beacons

    NARCIS (Netherlands)

    Wijngaarden, S.J. van; Bronkhorst, A.W.; Boer, L.C.

    2005-01-01

    Auditory evacuation beacons can be used to guide people to safe exits, even when vision is totally obscured by smoke. Conventional beacons make use of modulated noise signals. Controlled evacuation experiments show that such signals require explicit instructions and are often misunderstood. A new si

  17. Scouting the spectrum for interstellar travellers

    CERN Document Server

    Garcia-Escartin, Juan Carlos

    2012-01-01

    Advanced civilizations capable of interstellar travel, if they exist, are likely to have advanced propulsion methods. Spaceships moving at high speeds would leave a particular signature which could be detected from Earth. We propose a search based on the properties of light reflecting from objects travelling at relativistic speeds. Based on the same principles, we also propose a simple interstellar beacon with a solar sail.

  18. Interstellar PAHs

    Science.gov (United States)

    Allamandola, Louis J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Tremendous strides have been made in our understanding of interstellar material over the past twenty years thanks to significant, parallel developments in two closely related areas: observational astronomy and laboratory astrophysics. Twenty years ago the composition of interstellar dust was largely guessed at and the notion of abundant, gas phase, polycyclic aromatic hydrocarbons (PAHs) anywhere in the interstellar medium (ISM) considered impossible. Today the dust composition of the diffuse and dense ISM is reasonably well constrained and the spectroscopic case for interstellar PAHs, shockingly large molecules by early interstellar chemistry standards, is very strong.

  19. A new class of SETI beacons that contain information (22-aug-2010)

    CERN Document Server

    Harp, G R; Blair, Samantha K; Arbunich, J; Backus, P R; Tarter, J C

    2012-01-01

    In the cm-wavelength range, an extraterrestrial electromagnetic narrow band (sine wave) beacon is an excellent choice to get alien attention across interstellar distances because 1) it is not strongly affected by interstellar / interplanetary dispersion or scattering, and 2) searching for narrowband signals is computationally efficient (scales as Ns log(Ns) where Ns = number of voltage samples). Here we consider a special case wideband signal where two or more delayed copies of the same signal are transmitted over the same frequency and bandwidth, with the result that ISM dispersion and scattering cancel out during the detection stage. Such a signal is both a good beacon (easy to find) and carries arbitrarily large information rate (limited only by the atmospheric transparency to about 10 GHz). The discovery process uses an autocorrelation algorithm, and we outline a compute scheme where the beacon discovery search can be accomplished with only 2x the processing of a conventional sine wave search, and discuss...

  20. Interstellar Extinction

    Science.gov (United States)

    Gontcharov, G. A.

    2016-12-01

    This review describes our current understanding of interstellar extinction. This differ substantially from the ideas of the 20th century. With infrared surveys of hundreds of millions of stars over the entire sky, such as 2MASS, SPITZER-IRAC, and WISE, we have looked at the densest and most rarefied regions of the interstellar medium at distances of a few kpc from the Sun. Observations at infrared and microwave wavelengths, where the bulk of the interstellar dust absorbs and radiates, have brought us closer to an understanding of the distribution of the dust particles on scales of the Galaxy and the universe. We are in the midst of a scientific revolution in our understanding of the interstellar medium and dust. Progress in, and the key results of, this revolution are still difficult to predict. Nevertheless, (a) a physically justified model has been developed for the spatial distribution of absorbing material over the nearest few kiloparsecs, including the Gould belt as a dust container, which gives an accurate estimate of the extinction for any object just by its galactic coordinates. It is also clear that (b) the interstellar medium contains roughly half the mass of matter in the galactic vicinity of the solar system (the other half is made up of stars, their remnants, and dark matter) and (c) the interstellar medium and, especially, dust, differ substantially in different regions of space and deep space cannot be understood by only studying near space.

  1. 低占空比无线传感器网络同步 MAC 协议最优信标间隔分析%The Optimal Beacon Interval for Synchronous MAC in Low Duty-Cycle Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    邢宇龙; 陈永锐; 易卫东; 段成华

    2016-01-01

    Energy efficiency is a fundamental theme in the design of wireless sensor networks protocols ,especially for medium access control (MAC) protocols .An energy‐efficient MAC protocol can significantly elongate the lifetime of wireless sensor networks by reducing the duty‐cycle of sensor nodes to an ultra‐low level .Synchronous MAC can be even more efficient in data transfer at the cost of requiring tight time synchronization through periodical beacon dissemination . The length of the beacon interval may greatly affect the energy efficiency of a synchronous MAC .A shorter beacon interval leads to higher synchronization cost due to frequent beacon sending and receiving ,while a longer beacon interval will lead to a larger guard time and longer idle listening due to clock drift . Therefore ,there is a tradeoff between these two parts of energy consumption .In this paper ,we investigate the optimal beacon interval for synchronous MAC in low duty‐cycle sensor networks ,and then present a strategy that adaptively utilizes the optimal beacon interval in a TDMA‐based MAC protocol (called Opt‐TDMA) .By configuring the beacon interval to its optimal value according to the data packets rate and network size ,Opt‐TDMA can reduce the overall power consumption of both sending/receiving beacons and data packets . Experimental results demonstrate that Opt‐TDMA is more energy‐efficient than pure TDMA protocol and SCP‐MAC by using optimal beacon interval and contention‐free transmission .%能量效率是无线传感器网络协议设计的首要考虑因素。无线传感器网络中,介质访问控制层(medium access control ,MAC)协议通过降低节点的占空比来降低网络能耗,延长网络的生命周期。相比其他 MAC 协议,尽管同步 MAC 需要周期性分发信标来保持严格的时间同步,但却在数据传输方面具有更高的能量效率。信标间隔的长短直接影响同步 M AC 能量效率的高低。一方面

  2. New frontiers of molecular beacons: signal amplification and nanomachines

    DEFF Research Database (Denmark)

    Della Vedova, Paolo

    2013-01-01

    Gene expression is the process in which information stored into a gene is used to create a functional gene product, for example a protein or a functional RNA. Gene expression is used by all living organism to control cell life, differentiation, regeneration and cancer genesis. Molecular beacons...... provide a useful way to detect gene expression inside living cells without influencing the cell behavior. Molecular beacons are a particular kind of nucleic acid based probes composed by an oligonucleotide chain which assumes a hairpin configuration, encoding the target sequence of interest (loop) flanked...... section gives initially an overview of the molecular beacon technology usability and working principle. Later on the mechanism of molecular beacon’s internalization by SLO treatment was theoretically and experimentally investigated to determine optimal transfection condition and actual cell loading...

  3. Interstellar holography

    NARCIS (Netherlands)

    Walker, M. A.; Koopmans, L. V. E.; Stinebring, D. R.; van Straten, W.

    2008-01-01

    The dynamic spectrum of a radio pulsar is an in-line digital hologram of the ionized interstellar medium. It has previously been demonstrated that such holograms permit image reconstruction, in the sense that one can determine an approximation to the complex electric field values as a function of Do

  4. COSPAS-SARSAT Beacon Certification Facility

    Data.gov (United States)

    Federal Laboratory Consortium — EPG's COSPAS-SARSAT Beacon Certification Facility is one of five certification facilities in the world. Formal certifications are available for all beacon types and...

  5. 47 CFR 97.203 - Beacon station.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 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, Technician Plus, General, Advanced or Amateur Extra Class operator license may be a beacon. A...

  6. Tight Bounds for Beacon-Based Coverage in Simple Rectilinear Polygons

    KAUST Repository

    Bae, Sang Won

    2016-03-21

    We establish tight bounds for beacon-based coverage problems. In particular, we show that $$\\\\lfloor \\\\frac{n}{6} \\ floor $$⌊n6⌋ beacons are always sufficient and sometimes necessary to cover a simple rectilinear polygon P with n vertices. When P is monotone and rectilinear, we prove that this bound becomes $$\\\\lfloor \\\\frac{n+4}{8} \\ floor $$⌊n+48⌋. We also present an optimal linear-time algorithm for computing the beacon kernel of P.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  9. Interstellar Ices

    CERN Document Server

    Boogert, A C A

    2003-01-01

    Currently ~36 different absorption bands have been detected in the infrared spectra of cold, dense interstellar and circumstellar environments. These are attributed to the vibrational transitions of ~17 different molecules frozen on dust grains. We review identification issues and summarize the techniques required to extract information on the physical and chemical evolution of these ices. Both laboratory simulations and line of sight studies are essential. Examples are given for ice bands observed toward high mass protostars, fields stars and recent work on ices in disks surrounding low mass protostars. A number of clear trends have emerged in recent years. One prominent ice component consists of an intimate mixture between H2O, CH3OH and CO2 molecules. Apparently a stable balance exists between low temperature hydrogenation and oxidation reactions on grain surfaces. In contrast, an equally prominent ice component, consisting almost entirely of CO, must have accreted directly from the gas phase. Thermal proc...

  10. INTERSTELLAR TURBULENCE

    Directory of Open Access Journals (Sweden)

    D. Falceta-Gonçalves

    2011-01-01

    Full Text Available The Interstellar Medium (ISM is a complex, multi-phase system, where the history of the stars occurs. The processes of birth and death of stars are strongly coupled to the dynamics of the ISM. The observed chaotic and diffusive motions of the gas characterize its turbulent nature. Understanding turbulence is crucial for understanding the star-formation process and the energy-mass feedback from evolved stars. Magnetic fields, threading the ISM, are also observed, making this effort even more difficult. In this work, I briefly review the main observations and the characterization of turbulence from these observable quantities. Following on, I provide a review of the physics of magnetized turbulence. Finally, I will show the main results from theoretical and numerical simulations, which can be used to reconstruct observable quantities, and compare these predictions to the observations.

  11. Underwater Acoustic Beacon Location System

    Science.gov (United States)

    2016-12-23

    transpose operator is a standard operator in linear or matrix algebra . The transpose operator converts the row vector   T aaaa z,y,x=P to a column...February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...300087 1 of 31 UNDERWATER ACOUSTIC BEACON LOCATION SYSTEM [0001] The present application claims the benefit of United States Provisional

  12. Development and optimization of an analytical system for volatile organic compound analysis coming from the heating of interstellar/cometary ice analogues.

    Science.gov (United States)

    Abou Mrad, Ninette; Duvernay, Fabrice; Theulé, Patrice; Chiavassa, Thierry; Danger, Grégoire

    2014-08-19

    This contribution presents an original analytical system for studying volatile organic compounds (VOC) coming from the heating and/or irradiation of interstellar/cometary ice analogues (VAHIIA system) through laboratory experiments. The VAHIIA system brings solutions to three analytical constraints regarding chromatography analysis: the low desorption kinetics of VOC (many hours) in the vacuum chamber during laboratory experiments, the low pressure under which they sublime (10(-9) mbar), and the presence of water in ice analogues. The VAHIIA system which we developed, calibrated, and optimized is composed of two units. The first is a preconcentration unit providing the VOC recovery. This unit is based on a cryogenic trapping which allows VOC preconcentration and provides an adequate pressure allowing their subsequent transfer to an injection unit. The latter is a gaseous injection unit allowing the direct injection into the GC-MS of the VOC previously transferred from the preconcentration unit. The feasibility of the online transfer through this interface is demonstrated. Nanomoles of VOC can be detected with the VAHIIA system, and the variability in replicate measurements is lower than 13%. The advantages of the GC-MS in comparison to infrared spectroscopy are pointed out, the GC-MS allowing an unambiguous identification of compounds coming from complex mixtures. Beyond the application to astrophysical subjects, these analytical developments can be used for all systems requiring vacuum/cryogenic environments.

  13. The ANTARES optical beacon system

    Energy Technology Data Exchange (ETDEWEB)

    Ageron, M. [CPPM - Centre de Physique des Particules de Marseille, CNRS/IN2P3 et Universite de la Mediterranee, 163 Avenue de Luminy, Case 902, 13288 Marseille Cedex 9 (France); Aguilar, J.A. [IFIC - Instituto de Fisica Corpuscular, Edificios de Investigacion de Paterna, CSIC - Universitat de Valencia, Apdo. de Correos 22085, 46071 Valencia (Spain)]. E-mail: J.A.Aguilar@ific.uv.es; Albert, A. [GRPHE - Groupe de Recherche en Physique des Hautes Energies, Universite de Haute Alsace, 61 Rue Albert Camus, 68093 Mulhouse Cedex (France)) (and others)

    2007-08-11

    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.

  14. BBIS: Beacon Bus Information System

    Science.gov (United States)

    Kasim, Shahreen; Hafit, Hanayanti; Pei Juin, Kong; Afizah Afif, Zehan; Hashim, Rathiah; Ruslai, Husni; Jahidin, Kamaruzzaman; Syafwan Arshad, Mohammad

    2016-11-01

    Lack of bus information for example bus timetable, status of the bus and messy advertisement on bulletin board at the bus stop will give negative impact to tourist. Therefore, a real-time update bus information bulletin board provides all information needed so that passengers can save their bus information searching time. Supported with Android or iOS, Beacon Bus Information System (BBIS) provides bus information between Batu Pahat and Kluang area. BBIS is a system that implements physical web technology and interaction on demand. It built on Backend-as-a-Service, a cloud solution and Firebase non relational database as data persistence backend and syncs between user client in the real-time. People walk through bus stop with smart device and do not require any application. Bluetooth Beacon is used to achieve smart device's best performance of data sharing. Intellij IDEA 15 is one of the tools that that used to develop the BBIS system. Multi-language included front end and backend supported Integration development environment (IDE) helped to speed up integration process.

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

    Science.gov (United States)

    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

  16. Establishment of an accurate and fast detection method using molecular beacons in loop-mediated isothermal amplification assay

    Science.gov (United States)

    Liu, Wei; Huang, Simo; Liu, Ningwei; Dong, Derong; Yang, Zhan; Tang, Yue; Ma, Wen; He, Xiaoming; Ao, Da; Xu, Yaqing; Zou, Dayang; Huang, Liuyu

    2017-01-01

    This study established a constant-temperature fluorescence quantitative detection method, combining loop-mediated isothermal amplification (LAMP) with molecular beacons. The advantages of LAMP are its convenience and efficiency, as it does not require a thermocycler and results are easily visualized by the naked eye. However, a major disadvantage of current LAMP techniques is the use of indirect evaluation methods (e.g., electrophoresis, SYBR Green I dye, precipitation, hydroxynaphthol blue dye, the turbidimetric method, calcein/Mn2+ dye, and the composite probe method), which cannot distinguish between the desired products and products of nonspecific amplification, thereby leading to false positives. Use of molecular beacons avoids this problem because molecular beacons produce fluorescence signals only when binding to target DNA, thus acting as a direct indicator of amplification products. Our analyses determined the optimal conditions for molecular beacons as an evaluation tool in LAMP: beacon length of 25–45 bp, beacon concentration of 0.6–1 pmol/μL, and reaction temperature of 60–65 °C. In conclusion, we validated a novel molecular beacon loop-mediated isothermal amplification method (MB-LAMP), realizing the direct detection of LAMP product. PMID:28059137

  17. The ANTARES Optical Beacon System

    CERN Document Server

    Ageron, M; 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 R; 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; Compere, 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, P; Graf, K; Hallewell, G; Harakeh, M N; Hartmann, B; Heijboer, A; Heine, E; Hello, Y; Hernández-Rey, J J; Hossl, J; Hoffman, C; Hogenbirk, J; Hubbard, John 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; Kudryavtsev, 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; Löhner, H; Loucatos, Sotirios 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, Nathalie; Payre, P; Peek, H; Pérez, 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; Rethore, F; Rewiersma, P A M; 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 A; 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 K A; Wobbe, G; De Wolf, E; Yao, A F; Zaborov, D; Zaccone, Henri; De Dios-Zornoza-Gomez, Juan; Zúñiga, J; al, et

    2007-01-01

    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 ...

  18. Beacon data acquisition and display system

    Science.gov (United States)

    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. Interstellar Fullerene Compounds and Diffuse Interstellar Bands

    CERN Document Server

    Omont, Alain

    2015-01-01

    Recently, the presence of fullerenes in the interstellar medium (ISM) has been confirmed, especially with the first confirmed identification of two strong diffuse interstellar bands (DIBs) with C60+. This justifies reassesing the importance of interstellar fullerenes of various sizes with endohedral or exohedral inclusions and heterofullerenes (EEHFs). The phenomenology of fullerenes is complex. In addition to formation in shock shattering, fully dehydrogenated PAHs in diffuse interstellar (IS) clouds could perhaps efficiently transform into fullerenes including EEHFs. But it is extremely difficult to assess their expected abundance, composition and size distribution, except for C60+. As often suggested, EEHFs share many properties with C60, as regards stability, formation/destruction, chemical processes and many basic spectral features. We address the importance of various EEHFs as possible DIB carriers. Specifically, we discuss IS properties and the contributions of fullerenes of various sizes and charge su...

  20. Interstellar Molecules Their Laboratory and Interstellar Habitat

    CERN Document Server

    Yamada, Koichi M T

    2011-01-01

    This book deals with the astrophysics and spectroscopy of the interstellar molecules. In the introduction, overview and history of interstellar observations are described in order to help understanding how the modern astrophysics and molecular spectroscopy have been developed interactively. The recent progress in the study of this field, after the 4th Cologne-Bonn-Zermatt symposium 2003 is briefly summarized. Furthermore, the basic knowledge of molecular spectroscopy, which is essential to correctly comprehend the astrophysical observations, is presented in a compact form.

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

    Science.gov (United States)

    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.

  2. Study of an Innovative Indoor Robotic Navigation Approach Based on Beacons and PSD

    Directory of Open Access Journals (Sweden)

    Wang Zhenxing

    2016-01-01

    Full Text Available In this paper, innovative indoor navigation methods have been proposed to meet the challenges in robotic navigation systems. The general positioning methods for robotic navigation include vision-based approaches, WIFI beacons, infrared beacons, ultrasonic beacons, etc. However, the common problem with these methods is their inaccuracy. Especially, improving the precision of robotic positioning mechanisms is the key to indoor navigation systems. This paper proposes an approach that combines the external rotating beacon with an internal rotation of position sensitive devices (PSD which are installed on the robot. While two infrared beams from an external beacon source are equally projected to both sides of the PSD, the robot‟s position can be calculated precisely. The high performance and accurate results can be achieved by optimizing the rotation aligning time, dividing the working area, and compensating errors with information fusion. In comparison with other generic approaches, this proposed innovative approach requires less computing resources and is easier to implement due to its much lower complexity for the computing algorithms.

  3. Beach Advisory and Closing Online Notification (BEACON) system

    Data.gov (United States)

    U.S. Environmental Protection Agency — Beach Advisory and Closing Online Notification system (BEACON) is a colletion of state and local data reported to EPA about beach closings and advisories. BEACON is...

  4. iBeacon technology in the development of mobile applications

    OpenAIRE

    2015-01-01

    iBeacon technology, made possible by BLE, enables mobile application developers to base their applications on proximity. We would like to know how proximity can be integrated in the development of mobile applications. In the thesis we take a deeper look at iBeacon technology where monitoring and ranging are examined and the differences between location and proximity explained. Available options used for the configuration of iBeacons are also presented. Then two existing iBeacon applications a...

  5. Is interstellar archeology possible?

    Science.gov (United States)

    Carrigan, Richard A.

    2012-09-01

    Searching for signatures of cosmic-scale archeological artifacts such as Dyson spheres is an interesting alternative to conventional radio SETI. Uncovering such an artifact does not require the intentional transmission of a signal on the part of the original civilization. This type of search is called interstellar archeology or sometimes cosmic archeology. A variety of interstellar archeology signatures is discussed including non-natural planetary atmospheric constituents, stellar doping, Dyson spheres, as well as signatures of stellar, and galactic-scale engineering. The concept of a Fermi bubble due to interstellar migration is reviewed in the discussion of galactic signatures. These potential interstellar archeological signatures are classified using the Kardashev scale. A modified Drake equation is introduced. With few exceptions interstellar archeological signatures are clouded and beyond current technological capabilities. However SETI for so-called cultural transmissions and planetary atmosphere signatures are within reach.

  6. Analytically modelling the performance of piggybacking on beacons in VANETs

    NARCIS (Netherlands)

    Klein Wolterink, W.; Heijenk, G.; Berg, J.L. van den

    2012-01-01

    Piggybacking on beacons is a forwarding technique in vehicular ad-hoc networks (VANET) as a means to disseminate data. With this technique data is attached to and transmitted along with scheduled beacons. Nodes are assumed to beacon asynchronously. In this paper we present a first version of an anal

  7. 14 CFR 171.269 - Marker beacon performance requirements.

    Science.gov (United States)

    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 equipment...

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

    Science.gov (United States)

    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.

  9. An aptamer beacon responsive to botulinum toxins.

    Science.gov (United States)

    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.

  10. Doing Forensic on DTUsat-2 Using the Beacon Counter

    DEFF Research Database (Denmark)

    Fléron, René

    2016-01-01

    DTUsat-2 was launched into a Polar LEO on a Dnepr rocket out of Yasny on 19th June 2014. After the first few days of beacon recording and precise orbit determination it became apparent that all was not nominal. One notable thing was the relatively low beacon count number. The beacon count reflects...... how many times the communication system has generated and transmitted a beacon. When nominal the number will reach 32767 in about 22.5 days before rolling over. Not only did we observe a low beacon count number but most surprisingly the counter seemed the restart right before AOS when the satellite...... AOS were the satellite should have maximum power. A thorough investigation using modelling and beacon count mapping has been conducted in order to understand why the satellite does not operate nominally and why the beacon counter maps out contradictive to our initial understandings....

  11. The galactic interstellar medium

    CERN Document Server

    Burton, WB; Genzel, R

    1992-01-01

    This volume contains the papers of three extended lectures addressing advanced topics in astronomy and astrophysics. The topics discussed include the most recent observational data on interstellar matter outside our galaxy and the physics and chemistry of molecular clouds.

  12. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    XIANG FuYuan; LIANG ShunLin; LI AiGen

    2009-01-01

    The diffuse interstellar bands (DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s, the exact nature of DIBs still remains unclear. This article reviews the history of the detec-tions of DIBs in the Milky Way and external galaxies, the major observational characteristics of DIBs, the correlations or anti-correlations among DIBs or between DIBs and other interstellar features (e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise), and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  13. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The diffuse interstellar bands(DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s,the exact nature of DIBs still remains unclear. This article reviews the history of the detections of DIBs in the Milky Way and external galaxies,the major observational characteristics of DIBs,the correlations or anti-correlations among DIBs or between DIBs and other interstellar features(e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise),and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  14. Interstellar organic chemistry.

    Science.gov (United States)

    Sagan, C.

    1972-01-01

    Most of the interstellar organic molecules have been found in the large radio source Sagittarius B2 toward the galactic center, and in such regions as W51 and the IR source in the Orion nebula. Questions of the reliability of molecular identifications are discussed together with aspects of organic synthesis in condensing clouds, degradational origin, synthesis on grains, UV natural selection, interstellar biology, and contributions to planetary biology.

  15. Interstellar organic chemistry.

    Science.gov (United States)

    Sagan, C.

    1972-01-01

    Most of the interstellar organic molecules have been found in the large radio source Sagittarius B2 toward the galactic center, and in such regions as W51 and the IR source in the Orion nebula. Questions of the reliability of molecular identifications are discussed together with aspects of organic synthesis in condensing clouds, degradational origin, synthesis on grains, UV natural selection, interstellar biology, and contributions to planetary biology.

  16. Laboratory Astrochemistry: Interstellar PAHs

    Science.gov (United States)

    Salama, Farid; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are now considered to be an important and ubiquitous component of the organic material in space. PAHs are found in a large variety of extraterrestrial materials such as interplanetary dust particles (IDPs) and meteoritic materials. PAHs are also good candidates to account for the infrared emission bands (UIRs) and the diffuse interstellar optical absorption bands (DIBs) detected in various regions of the interstellar medium. The recent observations made with the Infrared Space Observatory (ISO) have confirmed the ubiquitous nature of the UIR bands and their carriers. PAHs are thought to form through chemical reactions in the outflow from carbon-rich stars in a process similar to soot formation. Once injected in the interstellar medium, PAHs are further processed by the interstellar radiation field, interstellar shocks and energetic particles. A major, dedicated, laboratory effort has been undertaken to measure the physical and chemical characteristics of these complex molecules and their ions under experimental conditions that mimic the interstellar conditions. These measurements require collision-free conditions where the molecules and ions are cold and chemically isolated. The spectroscopy of PAHs under controlled conditions represents an essential diagnostic tool to study the evolution of extraterrestrial PAHs. The Astrochemistry Laboratory program will be discussed through its multiple aspects: (1) objectives, (2) approach and techniques adopted, (3) adaptability to the nature of the problem(s), and (4) results and implications for astronomy as well as for molecular spectroscopy. A review of the data generated through laboratory simulations of space environments and the role these data have played in our current understanding of the properties of interstellar PAHs will be presented. The discussion will also introduce the newest generation of laboratory experiments that are currently being developed in order to provide a

  17. Interstellar Antifreeze: Ethylene Glycol

    Science.gov (United States)

    Hollis, J. M.; Lovas, F. J.; Jewell, P. R.; Coudert, L. H.

    2002-01-01

    Interstellar ethylene glycol (HOCH2CH2,OH) has been detected in emission toward the Galactic center source Sagittarius B2(N-LMH) by means of several millimeter-wave rotational torsional transitions of its lowest energy conformer. The types and kinds of molecules found to date in interstellar clouds suggest a chemistry that favors aldehydes and their corresponding reduced alcohols-e.g., formaldehyde (H2CO)/methanol (CH3OH), acetaldehyde (CH3CHO)/ethanol (CH3CH2OH). Similarly, ethylene glycol is the reduced alcohol of glycolaldehyde (CH2OHCHO), which has also been detected toward Sgr B2(N-LMH). While there is no consensus as to how any such large complex molecules are formed in the interstellar clouds, atomic hydrogen (H) and carbon monoxide (CO) could form formaldehyde on grain surfaces, but such surface chemistry beyond that point is uncertain. However, laboratory experiments have shown that the gas-phase reaction of atomic hydrogen (H) and solid-phase CO at 10-20 K can produce formaldehyde and methanol and that alcohols and other complex molecules can be synthesized from cometary ice analogs when subject to ionizing radiation at 15 K. Thus, the presence of aldehyde/ reduced alcohol pairs in interstellar clouds implies that such molecules are a product of a low-temperature chemistry on grain surfaces or in grain ice mantles. This work suggests that aldehydes and their corresponding reduced alcohols provide unique observational constraints on the formation of complex interstellar molecules.

  18. Localization with a Mobile Beacon in Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sangho Lee

    2012-04-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  20. Validation of the Calypso Surface Beacon Transponder.

    Science.gov (United States)

    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

  1. The Local Interstellar Medium

    CERN Document Server

    Redfield, S

    2006-01-01

    The Local Interstellar Medium (LISM) is a unique environment that presents an opportunity to study general interstellar phenomena in great detail and in three dimensions. In particular, high resolution optical and ultraviolet spectroscopy have proven to be powerful tools for addressing fundamental questions concerning the physical conditions and three-dimensional (3D) morphology of this local material. After reviewing our current understanding of the structure of gas in the solar neighborhood, I will discuss the influence that the LISM can have on stellar and planetary systems, including LISM dust deposition onto planetary atmospheres and the modulation of galactic cosmic rays through the astrosphere - the balancing interface between the outward pressure of the magnetized stellar wind and the inward pressure of the surrounding interstellar medium. On Earth, galactic cosmic rays may play a role as contributors to ozone layer chemistry, planetary electrical discharge frequency, biological mutation rates, and cl...

  2. Interstellar and circumstellar fullerenes

    CERN Document Server

    Bernard-Salas, J; Jones, A P; Peeters, E; Micelotta, E R; Otsuka, M; Sloan, G C; Kemper, F; Groenewegen, M

    2014-01-01

    Fullerenes are a particularly stable class of carbon molecules in the shape of a hollow sphere or ellipsoid that might be formed in the outflows of carbon stars. Once injected into the interstellar medium (ISM), these stable species survive and are thus likely to be widespread in the Galaxy where they contribute to interstellar extinction, heating processes, and complex chemical reactions. In recent years, the fullerene species C60 (and to a lesser extent C70) have been detected in a wide variety of circumstellar and interstellar environments showing that when conditions are favourable, fullerenes are formed efficiently. Fullerenes are the first and only large aromatics firmly identified in space. The detection of fullerenes is thus crucial to provide clues as to the key chemical pathways leading to the formation of large complex organic molecules in space, and offers a great diagnostic tool to describe the environment in which they reside. Since fullerenes share many physical properties with PAHs, understand...

  3. Indoor location estimation using radio beacons

    Science.gov (United States)

    Ahmad, Uzair; Lee, Young-Koo; Lee, Sungyoug; Park, Chongkug

    2007-12-01

    We present a simple location estimation method for developing radio beacon based location system in the indoor environments. It employs an online learning approach for making large scale location systems in a short time collaboratively. The salient features of our method are low memory requirements and simple computations which make it suitable for both distributed location-aware applications based on client-server model as well as privacy sensitive applications residing on stand alone devices.

  4. Decimal Integer Multiplication based on Molecular Beacons

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2013-12-01

    Full Text Available Due to the enhancement of circuit integration level, and the accelerating of working frequency of traditional computer, it requires components dimension must be constantly decreased. So encapsulation, etching and other problems of chip are becoming more and more difficult to solve, which causes its performance also become unstable. In order to overcome this problem, DNA computing as a new kind of molecular computing mode, with its high parallelism, huge amounts of storage capacity, low energy consumption advantages has received extensive attention. Being the same with traditional electronic computer, DNA computer is composed by arithmetic operations such as addition, subtraction, multiplication and dividing and basic logic units such as AND, OR, NON gate. This paper puts forward a new method to realize decimal integer multiplication based on molecular beacons. The algorithm firstly converts decimal integer to binary number, and then resolves the multiplication process into multiplication of current bit and addition of intermediate result after shifting two steps. Molecular beacon is used as multiplying unit, coding sequence is used as multiplier in this method. Based on the working principle of molecular beacon, multiplication operation of two one-bit binary is simulated. And by recording fluorescence status of molecular beacon to observe intermediate result and carry-bit situation, the final result can be obtained through addition after shifting. Examples prove that this method can realize decimal integer multiplication rapidly and accurately. This method is similar to multiplication system in traditional electronic computer, and it provides a simple, easier operation method for DNA computer to realize arithmetic operation.

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

    Science.gov (United States)

    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. ©AlphaMed Press.

  6. Improving adherence to the Epic Beacon ambulatory workflow.

    Science.gov (United States)

    Chackunkal, Ellen; Dhanapal Vogel, Vishnuprabha; Grycki, Meredith; Kostoff, Diana

    2017-06-01

    Computerized physician order entry has been shown to significantly improve chemotherapy safety by reducing the number of prescribing errors. Epic's Beacon Oncology Information System of computerized physician order entry and electronic medication administration was implemented in Henry Ford Health System's ambulatory oncology infusion centers on 9 November 2013. Since that time, compliance to the infusion workflow had not been assessed. The objective of this study was to optimize the current workflow and improve the compliance to this workflow in the ambulatory oncology setting. This study was a retrospective, quasi-experimental study which analyzed the composite workflow compliance rate of patient encounters from 9 to 23 November 2014. Based on this analysis, an intervention was identified and implemented in February 2015 to improve workflow compliance. The primary endpoint was to compare the composite compliance rate to the Beacon workflow before and after a pharmacy-initiated intervention. The intervention, which was education of infusion center staff, was initiated by ambulatory-based, oncology pharmacists and implemented by a multi-disciplinary team of pharmacists and nurses. The composite compliance rate was then reassessed for patient encounters from 2 to 13 March 2015 in order to analyze the effects of the determined intervention on compliance. The initial analysis in November 2014 revealed a composite compliance rate of 38%, and data analysis after the intervention revealed a statistically significant increase in the composite compliance rate to 83% ( p < 0.001). This study supports a pharmacist-initiated educational intervention can improve compliance to an ambulatory, oncology infusion workflow.

  7. Detecting the Beacons of Life with Exo-Life Beacon Space Telescope (ELBST)

    Science.gov (United States)

    Airapetian, V. S.; Danchi, W. C.; Chen, P. C.; Rabin, D. M.; Carpenter, K. G.; Mlynczak, M. G.

    2017-02-01

    We propose a new observational strategy, the “Exo-Life Beacon Space Telescope,” for detecting the signatures of “beacons” of life defined as high signal and low spectral resolution thermal emission from molecules associated with life signatures.

  8. Beach Advisory and Closing Online Notification (BEACON) system

    Science.gov (United States)

    Beach Advisory and Closing Online Notification system (BEACON) is a colletion of state and local data reported to EPA about beach closings and advisories. BEACON is the public-facing query of the Program tracking, Beach Advisories, Water quality standards, and Nutrients database (PRAWN) which tracks beach closing and advisory information.

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

    Science.gov (United States)

    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.…

  10. Getting Obstacle Avoidance Trajectory of Mobile Beacon for Localization

    Directory of Open Access Journals (Sweden)

    Huan-Qing CUI

    2010-11-01

    Full Text Available Localization is one of the most important technologies in wireless sensor network, and mobile beacon assisted localization is a promising localization method. The mobile beacon trajectory planning is a basic and important problem in these methods. There are many obstacles in the real world, which obstruct the moving of mobile beacon. This paper focuses on the obstacle avoidance trajectory planning scheme. After partitioning the deployment area with fixed cell decomposition, the beacon trajectory are divided into global and local trajectory. The approximate shortest global trajectory is obtained by depth-first search, greedy strategy method and ant colony algorithm, while local trajectory is any existing trajectories. Simulation results show that this method can avoid obstacles in the network deployment area, and the smaller cell size leads to longer beacon trajectory and more localizable sensor nodes.

  11. Indoor Navigation using Direction Sensor and Beacons

    Science.gov (United States)

    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.

  12. Interstellar hydrogen sulfide.

    Science.gov (United States)

    Thaddeus, P.; Kutner, M. L.; Penzias, A. A.; Wilson, R. W.; Jefferts, K. B.

    1972-01-01

    Hydrogen sulfide has been detected in seven Galactic sources by observation of a single line corresponding to the rotational transition from the 1(sub 10) to the 1(sub 01) levels at 168.7 GHz. The observations show that hydrogen sulfide is only a moderately common interstellar molecule comparable in abundance to H2CO and CS, but somewhat less abundant than HCN and much less abundant than CO.

  13. Diagnosis of Neisseria gonorrhoeae Using Molecular Beacon

    Science.gov (United States)

    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. PMID:25802857

  14. Diagnosis of Neisseria gonorrhoeae Using Molecular Beacon

    Directory of Open Access Journals (Sweden)

    Divya Sachdev

    2015-01-01

    Full Text Available 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.

  15. A Microfluidic Love-Wave Biosensing Device for PSA Detection Based on an Aptamer Beacon Probe.

    Science.gov (United States)

    Zhang, Feng; Li, Shuangming; Cao, Kang; Wang, Pengjuan; Su, Yan; Zhu, Xinhua; Wan, Ying

    2015-06-11

    A label-free and selective aptamer beacon-based Love-wave biosensing device was developed for prostate specific antigen (PSA) detection. The device consists of the following parts: LiTaO3 substrate with SiO2 film as wave guide layer, two set of inter-digital transducers (IDT), gold film for immobilization of the biorecongniton layer and a polydimethylsiloxane (PDMS) microfluidic channels. DNA aptamer, or "artificial antibody", was used as the specific biorecognition probe for PSA capture. Some nucleotides were added to the 3'-end of the aptamer to form a duplex with the 3'-end, turning the aptamer into an aptamer-beacon. Taking advantage of the selective target-induced assembly changes arising from the "aptamer beacon", highly selective and specific detection of PSA was achieved. Furthermore, PDMS microfluidic channels were designed and fabricated to realize automated quantitative sample injection. After optimization of the experimental conditions, the established device showed good performance for PSA detection between 10 ng/mL to 1 μg/mL, with a detection limit of 10 ng/mL. The proposed sensor might be a promising alternative for point of care diagnostics.

  16. Molecular Beacon-Based MicroRNA Imaging During Neurogenesis.

    Science.gov (United States)

    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.

  17. HF beacon network for ionospheric specification in Peru

    Science.gov (United States)

    Hysell, D. L.; Milla, M. A.; Vierinen, J.

    2016-12-01

    A growing network of HF beacon transmitters and receivers is being deployed in Peru for specifying the F region ionosphere regionally. The effort is motivated by ionospheric disturbances associated with equatorial spread F (ESF), especially disturbances arising under inauspicious ESF conditions. The beacons use dual frequencies (2.72 and 3.64 MHz). They incorporate PRN coding to afford group-delay measurements. Scatered power, Doppler shift, bearing, and polarization are also measured. An algorithm for inverting the beacon data combined with electron density profiles from Jicamarca is described. Data and representative solutions from recent campaigns will be reviewed.

  18. Chemical composition of interstellar dust

    Science.gov (United States)

    Das, Ankan; Chakrabarti, Sandip Kumar; Majumdar, Liton; Sahu, Dipen

    Study of chemical evolution of interstellar medium is well recognized to be a challenging task. Interstellar medium (ISM) is a rich reservoir of complex molecules. So far, around 180 gas phase molecules and around 20 molecular species on the interstellar dust have been detected in various regions of ISM, especially in regions of star formation. In last decade, it was well established that gas phase reactions alone cannot explain molecular abundances in ISM. Chemical reactions which occur on interstellar dust grains are essential to explain formation of several molecules especially hydrogenated species including simplest and most abundant molecule H2. Interstellar grains provide surface for accreted species to meet and react. Therefore, an understanding of formation of molecules on grain surfaces is of prime importance. We concentrate mainly on water, methanol, carbon dioxide, which constitute nearly 90% of the grain mantle. These molecules are detected on grain surface due to their strong absorption bands arising out of multiple vibrational modes. Water is the most abundant species (with a surface coverage >60% ) on a grain in dense interstellar medium. CO2 is second most abundant molecule in interstellar medium with an abundance of around 20% with respect to H2O. However, this can vary from cloud to cloud. In clouds like W 33A it could be even less than 5% of water abundance. The next most abundant molecule is CO, which is well studied ice with an abundance varying between 2%\\ to 15% of water. Methanol (CH3OH) is also very abundant having abundance 2% to 30% of water. Measurement of water deuterium fractionation is a relevant tool for understanding mechanisms of water formation and evolution from prestellar phase to formation of planets and comets. We are also considering deuterated species in our simulation. We use Monte Carlo method (considering multilayer regime) to mimic the exact scenario. We study chemical evolution of interstellar grain mantle by varying

  19. Modeling DNA beacons at the mesoscopic scale

    CERN Document Server

    Errami, Jalal; Theodorakopoulos, Nikos

    2007-01-01

    We report model calculations on DNA single strands which describe the equilibrium dynamics and kinetics of hairpin formation and melting. Modeling is at the level of single bases. Strand rigidity is described in terms of simple polymer models; alternative calculations performed using the freely rotating chain and the discrete Kratky-Porod models are reported. Stem formation is modeled according to the Peyrard-Bishop-Dauxois Hamiltonian. The kinetics of opening and closing is described in terms of a diffusion-controlled motion in an effective free energy landscape. Melting profiles, dependence of melting temperature on loop length, and kinetic time scales are in semiquantitative agreement with experimental data obtained from fluorescent DNA beacons forming poly(T) loops. Variation in strand rigidity is not sufficient to account for the large activation enthalpy of closing and the strong loop length dependence observed in hairpins forming poly(A) loops. Implications for modeling single strands of DNA or RNA are...

  20. Modeling on Bessel beam guide star beacon for wavefront sensing

    Science.gov (United States)

    Sun, Quan; Luo, Ruiyao; Yang, Yi; Wu, Wuming; Du, Shaojun; Ning, Yu

    2017-06-01

    Bessel beam has the advantages of reducing scattering artefacts and increasing the quality of the image and penetration. This paper proposed to generate a guide star by Bessel beam with vortex phase, and to use the beacon with special spot structure to measure the atmosphere turbulence aberrations. With the matching algorithm of measured characteristic spot in each subaperture, the detection accuracy of Hartmann wavefront sensor can be improved. Based on wave optics theory, the modeling of Bessel beam guide star and wavefront sensing system was built. The laser guide star beacon generated by Bessel beam with vortex phase and beacon echo wave measured by Hartmann sensor were both simulated. Compared with the results measured by echo wave from Gauss beam generated guide star beacon, this novel method can reduce the error of wavefront detection and increase the detection accuracy of Hartmann sensor.

  1. Visualizing Interstellar's Wormhole

    Science.gov (United States)

    James, Oliver; von Tunzelmann, Eugénie; Franklin, Paul; Thorne, Kip S.

    2015-06-01

    Christopher Nolan's science fiction movie Interstellar offers a variety of opportunities for students in elementary courses on general relativity theory. This paper describes such opportunities, including: (i) At the motivational level, the manner in which elementary relativity concepts underlie the wormhole visualizations seen in the movie; (ii) At the briefest computational level, instructive calculations with simple but intriguing wormhole metrics, including, e.g., constructing embedding diagrams for the three-parameter wormhole that was used by our visual effects team and Christopher Nolan in scoping out possible wormhole geometries for the movie; (iii) Combining the proper reference frame of a camera with solutions of the geodesic equation, to construct a light-ray-tracing map backward in time from a camera's local sky to a wormhole's two celestial spheres; (iv) Implementing this map, for example, in Mathematica, Maple or Matlab, and using that implementation to construct images of what a camera sees when near or inside a wormhole; (v) With the student's implementation, exploring how the wormhole's three parameters influence what the camera sees—which is precisely how Christopher Nolan, using our implementation, chose the parameters for Interstellar's wormhole; (vi) Using the student's implementation, exploring the wormhole's Einstein ring and particularly the peculiar motions of star images near the ring, and exploring what it looks like to travel through a wormhole.

  2. Visualizing Interstellar's Wormhole

    CERN Document Server

    James, Oliver; Franklin, Paul; Thorne, Kip S

    2015-01-01

    Christopher Nolan's science fiction movie Interstellar offers a variety of opportunities for students in elementary courses on general relativity theory. This paper describes such opportunities, including: (i) At the motivational level, the manner in which elementary relativity concepts underlie the wormhole visualizations seen in the movie. (ii) At the briefest computational level, instructive calculations with simple but intriguing wormhole metrics, including, e.g., constructing embedding diagrams for the three-parameter wormhole that was used by our visual effects team and Christopher Nolan in scoping out possible wormhole geometries for the movie. (iii) Combining the proper reference frame of a camera with solutions of the geodesic equation, to construct a light-ray-tracing map backward in time from a camera's local sky to a wormhole's two celestial spheres. (iv) Implementing this map, for example in Mathematica, Maple or Matlab, and using that implementation to construct images of what a camera sees when...

  3. Noise correlation-based adaptive polarimetric image representation for contrast enhancement of a polarized beacon in fog

    Science.gov (United States)

    Panigrahi, Swapnesh; Fade, Julien; Alouini, Mehdi

    2015-10-01

    We show the use of a simplified snapshot polarimetric camera along with an adaptive image processing for optimal detection of a polarized light beacon through fog. The adaptive representation is derived using theoretical noise analysis of the data at hand and is shown to be optimal in the Maximum likelihood sense. We report that the contrast enhancing optimal representation that depends on the background noise correlation differs in general from standard representations like polarimetric difference image or polarization filtered image. Lastly, we discuss a detection strategy to reduce the false positive counts.

  4. Detection of interstellar $CH_{3}$

    CERN Document Server

    Feuchtgruber, H; Van Dishoeck, E F; Wright, C M

    2000-01-01

    Observations with the Short Wavelength Spectrometer (SWS) onboard the {\\it Infrared Space Observatory} (ISO) have led to the first detection of the methyl radical ${\\rm CH_3}$ in the interstellar medium. The $\

  5. Turbulence in the Interstellar Medium

    CERN Document Server

    Falceta-Goncalves, D; Falgarone, E; Chian, A C -L

    2014-01-01

    Turbulence is ubiquitous in the insterstellar medium and plays a major role in several processes such as the formation of dense structures and stars, the stability of molecular clouds, the amplification of magnetic fields, and the re-acceleration and diffusion of cosmic rays. Despite its importance, interstellar turbulence, alike turbulence in general, is far from being fully understood. In this review we present the basics of turbulence physics, focusing on the statistics of its structure and energy cascade. We explore the physics of compressible and incompressible turbulent flows, as well as magnetized cases. The most relevant observational techniques that provide quantitative insights of interstellar turbulence are also presented. We also discuss the main difficulties in developing a three-dimensional view of interstellar turbulence from these observations. Finally, we briefly present what could be the the main sources of turbulence in the interstellar medium.

  6. Crowdsourcing for Context: Regarding Privacy in Beacon Encounters via Contextual Integrity

    National Research Council Canada - National Science Library

    Emmanuel Bello-Ogunu; Mohamed Shehab

    2016-01-01

    .... With Bluetooth Low Energy beacons, one of the latest technologies for providing proximity and indoor tracking, the current identifiers that characterize a beacon are not sufficient for ordinary users...

  7. The Interstellar Conspiracy

    Science.gov (United States)

    Johnson, Les; Matloff, Gregory L.

    2005-01-01

    If we were designing a human-carrying starship that could be launched in the not-too-distant future, it would almost certainly not use a warp drive to instantaneously bounce around the universe, as is done in Isaac Asimov's classic Foundation series or in episodes of Star Trek or Star Wars. Sadly, those starships that seem to be within technological reach could not even travel at high relativistic speeds, as does the interstellar ramjet in Poul Anderson's Tau Zero. Warp-speeds seem to be well outside the realm of currently understood physical law; proton-fusing ramjets may never be technologically feasible. Perhaps fortunately in our terrorist-plagued world, the economics of antimatter may never be attractive for large-scale starship propulsion. But interstellar travel will be possible within a few centuries, although it will certainly not be as fast as we might prefer. If humans learn how to hibernate, perhaps we will sleep our way to the stars, as do the crew in A. E. van Vogt's Far Centaurus. However, as discussed in a landmark paper in The Journal of the British Interplanetary Society, the most feasible approach to transporting a small human population to the planets (if any) of Alpha Centauri is the worldship. Such craft have often been featured in science fiction. See for example Arthur C. Clarke's Rendezvous with Rama, and Robert A. Heinlein's Orphans of the Sky. Worldships are essentially mobile versions of the O Neill free-space habitats. Constructed mostly from lunar and/or asteroidal materials, these solar-powered, multi-kilometer-dimension structures could house 10,000 to 100,000 humans in Earth-approximating environments. Artificial gravity would be provided by habitat rotation, and cosmic ray shielding would be provided by passive methods, such as habitat atmosphere and mass shielding, or magnetic fields. A late 21st century space-habitat venture might support itself economically by constructing large solar-powered satellites to beam energy back to

  8. Beacon-Less Geographic Routing in Real Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    Juan A. Sánchez; Rafael Marín-Pérez; Pedro M. Ruiz

    2008-01-01

    Geographic Routing (GR) algorithms require nodes to periodically transmit HELLO messages to allow neigh-bors to know their positions (beaconing mechanism). Beacon-less routing algorithms have recently been proposed to reduce the control overheads due to these messages. However, existing beacon-less algorithms have not considered realistic physical layers. Therefore, those algorithms cannot work properly in realistic scenarios. In this paper we present a new beacon-less routing protocol called BOSS. Its design is based on the conclusions of our open-field experiments using Tmote-sky sensors. BOSS is adapted to error-prone networks and incorporates a new mechanism to reduce collisions and duplicate messages produced during the selection of the next forwarder node. We compare BOSS with Beacon-Less Routing (BLR)and Contention-Based Forwarding (CBF) algorithms through extensive simulations. The results show that our scheme is able to achieve almost perfect packet delivery ratio (like BLR) while having a low bandwidth consumption (even lower than CBF). Additionally, we carried out an empirical evaluation in a real testbed that shows the correctness of our simulation results.

  9. Discovery of Interstellar CF+

    CERN Document Server

    Neufeld, D A; Menten, K M; Wolfire, M G; Black, J H; Schuller, F; Müller, H; Thorwirth, S; Gusten, R; Philipp, S

    2006-01-01

    We discuss the first astronomical detection of the CF+ (fluoromethylidynium) ion, obtained by observations of the J=1-0 (102.6 GHz), J=2-1 (205.2 GHz) and J=3-2 (307.7 GHz) rotational transitions toward the Orion Bar region. Our search for CF+, carried out using the IRAM 30m and APEX 12m telescopes, was motivated by recent theoretical models that predict CF+ abundances of a few times 1.E-10 in UV-irradiated molecular regions where C+ is present. The CF+ ion is produced by exothermic reactions of C+ with HF. Because fluorine atoms can react exothermically with H2, HF is predicted to be the dominant reservoir of fluorine, not only in well-shielded regions but also in the surface layers of molecular clouds where the C+ abundance is large. The observed CF+ line intensities imply the presence of CF+ column densities of at least 1.E+12 cm-2 over a region of size at least ~ 1 arcmin, in good agreement with theoretical predictions. They provide support for our current theories of interstellar fluorine chemistry, whic...

  10. Interstellar molecular clouds

    Science.gov (United States)

    Bally, J.

    1986-04-01

    The physical properties of the molecular phase of the interstellar medium are studied with regard to star formation and the structure of the Galaxy. Most observations of molecular clouds are made with single-dish, high-surface precision radio telescopes, with the best resolution attainable at 0.2 to 1 arcmin; the smallest structures that can be resolved are of order 10 to the 17th cm in diameter. It is now believed that: (1) most of the mass of the Galaxy is in the form of giant molecular clouds; (2) the largest clouds and those responsible for most massive star formation are concentrated in spiral arms; (3) the molecular clouds are the sites of perpetual star formation, and are significant in the chemical evolution of the Galaxy; (4) giant molecular clouds determine the evolution of the kinematic properties of galactic disk stars; (5) the total gas content is diminishing with time; and (6) most clouds have supersonic internal motions and do not form stars on a free-fall time scale. It is concluded that though progress has been made, more advanced instruments are needed to inspect the processes operating within stellar nurseries and to study the distribution of the molecular clouds in more distant galaxies. Instruments presently under construction which are designed to meet these ends are presented.

  11. Interstellar Solid Hydrogen

    CERN Document Server

    Lin, Ching Yeh; Walker, Mark A

    2011-01-01

    We consider the possibility that solid molecular hydrogen is present in interstellar space. If so cosmic-rays and energetic photons cause ionisation in the solid leading to the formation of H6+. This ion is not produced by gas-phase reactions and its radiative transitions therefore provide a signature of solid H2 in the astrophysical context. The vibrational transitions of H6+ are yet to be observed in the laboratory, but we have characterised them in a quantum-theoretical treatment of the molecule; our calculations include anharmonic corrections, which are large. Here we report on those calculations and compare our results with astronomical data. In addition to the H6+ isotopomer, we focus on the deuterated species (HD)3+ which is expected to dominate at low ionisation rates as a result of isotopic condensation reactions. We can reliably predict the frequencies of the fundamental bands for five modes of vibration. For (HD)3+ all of these are found to lie close to some of the strongest of the pervasive mid-in...

  12. Information Dissemination in VANETS by Piggybacking on Beacons - An Analysis of the Impact of Network Parameters

    NARCIS (Netherlands)

    Klein Wolterink, W.; Heijenk, G.J.; Karagiannis, G.

    2011-01-01

    Piggybacking on beacons is a forwarding technique that is regularly used in vehicular ad-hoc network (VANET) research as a means to disseminate data. With this technique data is attached to and transmitted along with scheduled beacons, without changing the timing of the beacons. In this paper we eva

  13. 76 FR 65216 - Beacon Medical Services, LLC, Aurora, CO; Notice of Negative Determination Regarding Application...

    Science.gov (United States)

    2011-10-20

    ... 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 Medical Services, LLC, Aurora, Colorado (Beacon Medical Services). The negative determination was issued on June 22...

  14. 33 CFR 149.580 - What are the requirements for a radar beacon?

    Science.gov (United States)

    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 (RACON...

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

    Science.gov (United States)

    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 requirements...

  16. 76 FR 17625 - Proposed Information Collection; Comment Request; Emergency Beacon Registrations

    Science.gov (United States)

    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, must...

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

    Science.gov (United States)

    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....

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

    Science.gov (United States)

    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…

  19. 78 FR 75392 - American Beacon Funds, et al.; Notice of Application

    Science.gov (United States)

    2013-12-11

    ...-Advised Fund as follows: (a) American Beacon Acadian Emerging Markets Managed Volatility Fund-- Acadian...--Bridgeway Capital Management, Inc.; (d) American Beacon Earnest Partners Emerging Markets Equity Fund--EARNEST Partners, LLC; (e) American Beacon Emerging Markets Fund--Brandes Investment Partners, LP,...

  20. Interstellar Dust Close to the Sun

    CERN Document Server

    Frisch, Priscilla C

    2012-01-01

    The low density interstellar medium (ISM) close to the Sun and inside of the heliosphere provides a unique laboratory for studying interstellar dust grains. Grain characteristics in the nearby ISM are obtained from observations of interstellar gas and dust inside of the heliosphere and the interstellar gas towards nearby stars. Comparison between the gas composition and solar abundances suggests that grains are dominated by olivines and possibly some form of iron oxide. Measurements of the interstellar Ne/O ratio by the Interstellar Boundary Explorer spacecraft indicate that a high fraction of interstellar oxygen in the ISM must be depleted onto dust grains. Local interstellar abundances are consistent with grain destruction in ~150 km/s interstellar shocks, provided that the carbonaceous component is hydrogenated amorphous carbon and carbon abundances are correct. Variations in relative abundances of refractories in gas suggest variations in the history of grain destruction in nearby ISM. The large observed ...

  1. Exploring the transformative potential of Bluetooth beacons in higher education

    Directory of Open Access Journals (Sweden)

    Kieran McDonald

    2016-11-01

    Full Text Available The growing ubiquity of smartphones and tablet devices integrated into personal, social and professional life, facilitated by expansive communication networks globally, has the potential to disrupt higher education. Academics and students are considering the future possibilities of exploiting these tools and utilising networks to consolidate and expand knowledge, enhancing learning gain. Bluetooth beacon technology has been developed by both Apple and Google as a way to situate digital information within physical spaces, and this paper reflects on a beacon intervention in a contemporary art school in higher education conducted by the authors intended to develop a situated community of practice in Art & Design. The paper describes the project, including relevant theoretical foundations and background to the beacon technology, with regards to the potential of using these devices to create a connected learning community by enhancing learning and facilitating knowledge creation in a borderless learning space.

  2. A Search for New Physics with the BEACON Mission

    CERN Document Server

    Turyshev, Slava G; Shao, Michael; Girerd, Andre

    2008-01-01

    The primary objective of the Beyond Einstein Advanced Coherent Optical Network (BEACON) mission is a search for new physics beyond general relativity by measuring the curvature of relativistic space-time around Earth. This curvature is characterized by the Eddington parameter \\gamma -- the most fundamental relativistic gravity parameter and a direct measure for the presence of new physical interactions. BEACON will achieve an accuracy of 1 x 10^{-9} in measuring the parameter \\gamma, thereby going a factor of 30,000 beyond the present best result involving the Cassini spacecraft. Secondary mission objectives include: (i) a direct measurement of the "frame-dragging" and geodetic precessions in the Earth's rotational gravitomagnetic field, to 0.05% and 0.03% accuracy correspondingly, (ii) first measurement of gravity's non-linear effects on light and corresponding 2nd order spatial metric's effects to 0.01% accuracy. BEACON will lead to robust advances in tests of fundamental physics -- this mission could disco...

  3. Indoor localization and beacon calibration using ultrasonic and radio frequency

    Science.gov (United States)

    Yoon, Jeong-Yong; Jung, Kyoo-Sick; Shin, Dong-Hun

    2005-12-01

    Using the ultrasonic and the radio frequency, a method for the robot localization and calibration was presented. The distance between the receiver and a beacon can be computed by using the difference between times of flight. The presented method uses the gradient of the maximum amplitude of the ultrasonic in order to measure the time of flight precisely. The measured three distances between the receiver and the beacon were used to compute the robot position by the direct inverse method and the iterated least square approximation method. This paper defines the calibration as the problem to find the location of 3 beacons and 3 robots, and presents 3 methods for it and found the 2B2R method as the best among them.

  4. Distributed localization using mobile beacons in wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    KUANG Xing-hong; SHAO Hui-he

    2007-01-01

    A new distributed node localization algorithm named mobile beacons-improved particle filter (MB-IPF) was proposed. In the algorithm, the mobile nodes equipped with globe position system (GPS) move around in the wireless sensor network (WSN) field based on the Gauss-Markov mobility model, and periodically broadcast the beacon messages. Each unknown node estimates its location in a fully distributed mode based on the received mobile beacons. The localization algorithm is based on the IPF and several refinements, including the proposed weighted centroid algorithm, the residual resampling algorithm, and the markov chain monte carlo (MCMC) method etc., which were also introduced for performance improvement. The simulation results show that our proposed algorithm is efficient for most applications.

  5. Protein analysis based on molecular beacon probes and biofunctionalized nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    With the completion of the human genome-sequencing project, there has been a resulting change in the focus of studies from genomics to proteomics. By utilizing the inherent advantages of molecular beacon probes and biofunctionalized nanoparticles, a series of novel principles, methods and techniques have been exploited for bioanalytical and biomedical studies. This review mainly discusses the applications of molecular beacon probes and biofunctionalized nanoparticles-based technologies for realtime, in-situ, highly sensitive and highly selective protein analysis, including the nonspecific or specific protein detection and separation, protein/DNA interaction studies, cell surface protein recognition, and antigen-antibody binding process-based bacteria assays. The introduction of molecular beacon probes and biofunctionalized nanoparticles into the protein analysis area would necessarily advance the proteomics research.

  6. Beacon Communities’ Public Health Initiatives: A Case Study Analysis

    Science.gov (United States)

    Massoudi, Barbara L.; Marcial, Laura H.; Haque, Saira; Bailey, Robert; Chester, Kelley; Cunningham, Shellery; Riley, Amanda; Soper, Paula

    2014-01-01

    Introduction: The Beacon Communities for Public Health (BCPH) project was launched in 2011 to gain a better understanding of the range of activities currently being conducted in population- and public health by the Beacon Communities. The project highlighted the successes and challenges of these efforts with the aim of sharing this information broadly among the public health community. Background: The Beacon Community Program, designed to showcase technology-enabled, community-based initiatives to improve outcomes, focused on: building and strengthening health information technology (IT) infrastructure and exchange capabilities; translating investments in health IT to measureable improvements in cost, quality, and population health; and, developing innovative approaches to performance measurement, technology, and care delivery. Methods: Four multimethod case studies were conducted based on a modified sociotechnical framework to learn more about public health initiative implementation and use in the Beacon Communities. Our methodological approach included using document review and semistructured key informant interviews. NACCHO Model Practice Program criteria were used to select the public health initiatives included in the case studies. Findings: Despite differences among the case studies, common barriers and facilitators were found to be present in all areas of the sociotechnical framework application including structure, people, technology, tasks, overarching considerations, and sustainability. Overall, there were many more facilitators (range = 7–14) present for each Beacon compared to barriers (range = 4–6). Discussion: Four influential promising practices were identified through the work: forging strong and sustainable partnerships; ensuring a good task-technology fit and a flexible and iterative design; fostering technology acceptance; and, providing education and demonstrating value. Conclusions: A common weakness was the lack of a framework or model for

  7. BEACON: automated tool for Bacterial GEnome Annotation ComparisON.

    Science.gov (United States)

    Kalkatawi, Manal; Alam, Intikhab; Bajic, Vladimir B

    2015-08-18

    Genome annotation is one way of summarizing the existing knowledge about genomic characteristics of an organism. There has been an increased interest during the last several decades in computer-based structural and functional genome annotation. Many methods for this purpose have been developed for eukaryotes and prokaryotes. Our study focuses on comparison of functional annotations of prokaryotic genomes. To the best of our knowledge there is no fully automated system for detailed comparison of functional genome annotations generated by different annotation methods (AMs). The presence of many AMs and development of new ones introduce needs to: a/ compare different annotations for a single genome, and b/ generate annotation by combining individual ones. To address these issues we developed an Automated Tool for Bacterial GEnome Annotation ComparisON (BEACON) that benefits both AM developers and annotation analysers. BEACON provides detailed comparison of gene function annotations of prokaryotic genomes obtained by different AMs and generates extended annotations through combination of individual ones. For the illustration of BEACON's utility, we provide a comparison analysis of multiple different annotations generated for four genomes and show on these examples that the extended annotation can increase the number of genes annotated by putative functions up to 27%, while the number of genes without any function assignment is reduced. We developed BEACON, a fast tool for an automated and a systematic comparison of different annotations of single genomes. The extended annotation assigns putative functions to many genes with unknown functions. BEACON is available under GNU General Public License version 3.0 and is accessible at: http://www.cbrc.kaust.edu.sa/BEACON/ .

  8. Beacon communities' public health initiatives: a case study analysis.

    Science.gov (United States)

    Massoudi, Barbara L; Marcial, Laura H; Haque, Saira; Bailey, Robert; Chester, Kelley; Cunningham, Shellery; Riley, Amanda; Soper, Paula

    2014-01-01

    The Beacon Communities for Public Health (BCPH) project was launched in 2011 to gain a better understanding of the range of activities currently being conducted in population- and public health by the Beacon Communities. The project highlighted the successes and challenges of these efforts with the aim of sharing this information broadly among the public health community. The Beacon Community Program, designed to showcase technology-enabled, community-based initiatives to improve outcomes, focused on: building and strengthening health information technology (IT) infrastructure and exchange capabilities; translating investments in health IT to measureable improvements in cost, quality, and population health; and, developing innovative approaches to performance measurement, technology, and care delivery. Four multimethod case studies were conducted based on a modified sociotechnical framework to learn more about public health initiative implementation and use in the Beacon Communities. Our methodological approach included using document review and semistructured key informant interviews. NACCHO Model Practice Program criteria were used to select the public health initiatives included in the case studies. Despite differences among the case studies, common barriers and facilitators were found to be present in all areas of the sociotechnical framework application including structure, people, technology, tasks, overarching considerations, and sustainability. Overall, there were many more facilitators (range = 7-14) present for each Beacon compared to barriers (range = 4-6). Four influential promising practices were identified through the work: forging strong and sustainable partnerships; ensuring a good task-technology fit and a flexible and iterative design; fostering technology acceptance; and, providing education and demonstrating value. A common weakness was the lack of a framework or model for the Beacon Communities evaluation work. Sharing a framework or approach

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

    Science.gov (United States)

    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.

  10. BEACON SYNCHRONIZATION TECHNOLOGY FOR “BEIDOU” TERRESTRIAL IMPROVEMENT SYSTEM

    Institute of Scientific and Technical Information of China (English)

    WEIJin-chen; TANGJi-qiang; SHENFeng

    2005-01-01

    Synchronization is an essential technology in the radio navigation system. The technique for improving the “Beidou” positioning ability is presented through constituting the terrestrial improvement system, and the beacon synchronization of the improvement system with the “Beidou” one-way time transfer model is realized.The direct digital synthesis (DDS) is adopted to generate the pseudo-random code clock having high precision and stability. Meanwhile, the CPLD device is used to design the synchronization pulse picking-up module, the spread spectrum PN code generator and the spread spectrum modulator. Measurement results indicate that the beacon synchronization has the high precision and the stability.

  11. Omnidirectional beacon-localization using a catadioptric system.

    Science.gov (United States)

    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.

  12. Depolarization canals and interstellar turbulence

    Science.gov (United States)

    Fletcher, A.; Shukurov, A.

    Recent radio polarization observations have revealed a plethora of unexpected features in the polarized Galactic radio background that arise from propagation effects in the random (turbulent) interstellar medium. The canals are especially striking among them, a random network of very dark, narrow regions clearly visible in many directions against a bright polarized Galactic synchrotron background. There are no obvious physical structures in the ISM that may have caused the canals, and so they have been called Faraday ghosts. They evidently carry information about interstellar turbulence but only now is it becoming clear how this information can be extracted. Two theories for the origin of the canals have been proposed; both attribute the canals to Faraday rotation, but one invokes strong gradients in Faraday rotation in the sky plane (specifically, in a foreground Faraday screen) and the other only relies on line-of-sight effects (differential Faraday rotation). In this review we discuss the physical nature of the canals and how they can be used to explore statistical properties of interstellar turbulence. This opens studies of magnetized interstellar turbulence to new methods of analysis, such as contour statistics and related techniques of computational geometry and topology. In particular, we can hope to measure such elusive quantities as the Taylor microscale and the effective magnetic Reynolds number of interstellar MHD turbulence.

  13. mRNA detection in living cell using phosphorothioate-modified molecular beacon

    Institute of Scientific and Technical Information of China (English)

    TANG HongXing; YANG XiaoHai; WANG KeMin; TAN WeiHong; LI Wei

    2009-01-01

    In this study, GFP mRNA in COS-7 cell and GFP-transfected COS-7 cell was detected in real time using phosphorothioate-modified molecular beacon based on living cell imaging method. Results showed that phosphorothioate-modified molecular beacon still kept the advantages of molecular beacon, such as, excellent selectivity, high sensitivity, and no separation detection. In addition, this modification could significantly increase the nuclease resistance of molecular beacon. Phosphorothioate-modified molecular beacon can efficiently reduce the false positive signal and improve the accuracy of living cell mRNA detection.

  14. Controlling the signal: Practical privacy protection of genomic data sharing through Beacon services.

    Science.gov (United States)

    Wan, Zhiyu; Vorobeychik, Yevgeniy; Kantarcioglu, Murat; Malin, Bradley

    2017-07-26

    Genomic data is increasingly collected by a wide array of organizations. As such, there is a growing demand to make summary information about such collections available more widely. However, over the past decade, a series of investigations have shown that attacks, rooted in statistical inference methods, can be applied to discern the presence of a known individual's DNA sequence in the pool of subjects. Recently, it was shown that the Beacon Project of the Global Alliance for Genomics and Health, a web service for querying about the presence (or absence) of a specific allele, was vulnerable. The Integrating Data for Analysis, Anonymization, and Sharing (iDASH) Center modeled a track in their third Privacy Protection Challenge on how to mitigate the Beacon vulnerability. We developed the winning solution for this track. This paper describes our computational method to optimize the tradeoff between the utility and the privacy of the Beacon service. We generalize the genomic data sharing problem beyond that which was introduced in the iDASH Challenge to be more representative of real world scenarios to allow for a more comprehensive evaluation. We then conduct a sensitivity analysis of our method with respect to several state-of-the-art methods using a dataset of 400,000 positions in Chromosome 10 for 500 individuals from Phase 3 of the 1000 Genomes Project. All methods are evaluated for utility, privacy and efficiency. Our method achieves better performance than all state-of-the-art methods, irrespective of how key factors (e.g., the allele frequency in the population, the size of the pool and utility weights) change from the original parameters of the problem. We further illustrate that it is possible for our method to exhibit subpar performance under special cases of allele query sequences. However, we show our method can be extended to address this issue when the query sequence is fixed and known a priori to the data custodian, so that they may plan stage their

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

    Science.gov (United States)

    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

  16. Robot-Beacon Distributed Range-Only SLAM for Resource-Constrained Operation.

    Science.gov (United States)

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

    2017-04-20

    This work deals with robot-sensor network cooperation where sensor nodes (beacons) are used as landmarks for Range-Only (RO) Simultaneous Localization and Mapping (SLAM). Most existing RO-SLAM techniques consider beacons as passive devices disregarding the sensing, computational and communication capabilities with which they are actually endowed. SLAM is a resource-demanding task. Besides the technological constraints of the robot and beacons, many applications impose further resource consumption limitations. This paper presents a scalable distributed RO-SLAM scheme for resource-constrained operation. It is capable of exploiting robot-beacon cooperation in order to improve SLAM accuracy while meeting a given resource consumption bound expressed as the maximum number of measurements that are integrated in SLAM per iteration. The proposed scheme combines a Sparse Extended Information Filter (SEIF) SLAM method, in which each beacon gathers and integrates robot-beacon and inter-beacon measurements, and a distributed information-driven measurement allocation tool that dynamically selects the measurements that are integrated in SLAM, balancing uncertainty improvement and resource consumption. The scheme adopts a robot-beacon distributed approach in which each beacon participates in the selection, gathering and integration in SLAM of robot-beacon and inter-beacon measurements, resulting in significant estimation accuracies, resource-consumption efficiency and scalability. It has been integrated in an octorotor Unmanned Aerial System (UAS) and evaluated in 3D SLAM outdoor experiments. The experimental results obtained show its performance and robustness and evidence its advantages over existing methods.

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

    Science.gov (United States)

    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.

  18. Theory of interstellar medium diagnostics

    Science.gov (United States)

    Fahr, H. J.

    1983-01-01

    The theoretical interpretation of observed interplanetary resonance luminescence patterns is used as one of the must promising methods to determine the state of the local interstellar medium (LISM). However, these methods lead to discrepant results that would be hard to understand in the framework of any physical LISM scenario. Assuming that the observational data are reliable, two possibilities which could help to resolve these discrepancies are discussed: (1) the current modeling of resonance luminescence patterns is unsatisfactory and has to be improved, and (2) the extrapolated interstellar parameters are not indicative of the unperturbed LISM state, but rather designate an intermediate state attained in the outer regions of the solar system. It is shown that a quantitative treatment of the neutral gas-plasma interaction effects in the interface between the heliospheric and the interstellar plasmas is of major importance for the correct understanding of the whole complex.

  19. Interstellar Isotopes: Prospects with ALMA

    Science.gov (United States)

    Charnley Steven B.

    2010-01-01

    Cold molecular clouds are natural environments for the enrichment of interstellar molecules in the heavy isotopes of H, C, N and O. Anomalously fractionated isotopic material is found in many primitive Solar System objects, such as meteorites and comets, that may trace interstellar matter that was incorporated into the Solar Nebula without undergoing significant processing. Models of the fractionation chemistry of H, C, N and O in dense molecular clouds, particularly in cores where substantial freeze-out of molecules on to dust has occurred, make several predictions that can be tested in the near future by molecular line observations. The range of fractionation ratios expected in different interstellar molecules will be discussed and the capabilities of ALMA for testing these models (e.g. in observing doubly-substituted isotopologues) will be outlined.

  20. A Microfluidic Love-Wave Biosensing Device for PSA Detection Based on an Aptamer Beacon Probe

    Directory of Open Access Journals (Sweden)

    Feng Zhang

    2015-06-01

    Full Text Available A label-free and selective aptamer beacon-based Love-wave biosensing device was developed for prostate specific antigen (PSA detection. The device consists of the following parts: LiTaO3 substrate with SiO2 film as wave guide layer, two set of inter-digital transducers (IDT, gold film for immobilization of the biorecongniton layer and a polydimethylsiloxane (PDMS microfluidic channels. DNA aptamer, or “artificial antibody”, was used as the specific biorecognition probe for PSA capture. Some nucleotides were added to the 3'-end of the aptamer to form a duplex with the 3'-end, turning the aptamer into an aptamer-beacon. Taking advantage of the selective target-induced assembly changes arising from the “aptamer beacon”, highly selective and specific detection of PSA was achieved. Furthermore, PDMS microfluidic channels were designed and fabricated to realize automated quantitative sample injection. After optimization of the experimental conditions, the established device showed good performance for PSA detection between 10 ng/mL to 1 μg/mL, with a detection limit of 10 ng/mL. The proposed sensor might be a promising alternative for point of care diagnostics.

  1. Interstellar Initiative Web Page Design

    Science.gov (United States)

    Mehta, Alkesh

    1999-01-01

    This summer at NASA/MSFC, I have contributed to two projects: Interstellar Initiative Web Page Design and Lenz's Law Relative Motion Demonstration. In the Web Design Project, I worked on an Outline. The Web Design Outline was developed to provide a foundation for a Hierarchy Tree Structure. The Outline would help design a Website information base for future and near-term missions. The Website would give in-depth information on Propulsion Systems and Interstellar Travel. The Lenz's Law Relative Motion Demonstrator is discussed in this volume by Russell Lee.

  2. The Warped Science of Interstellar

    CERN Document Server

    Luminet, Jean-Pierre

    2015-01-01

    The science fiction film, Interstellar, tells the story of a team of astronauts searching a distant galaxy for habitable planets to colonize. Interstellar's story draws heavily from contemporary science. The film makes reference to a range of topics, from established concepts such as fast-spinning black holes, accretion disks, tidal effects, and time dilation, to far more speculative ideas such as wormholes, time travel, additional space dimensions, and the theory of everything. The aim of this article is to decipher some of the scientific notions which support the framework of the movie.

  3. Infrared emission from interstellar PAHs

    Science.gov (United States)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    The mid-IR absorption and Raman spectra of polycyclic aromatic hydrocarbons (PAHs) and the mechanisms determining them are reviewed, and the implications for observations of similar emission spectra in interstellar clouds are considered. Topics addressed include the relationship between PAHs and amorphous C, the vibrational spectroscopy of PAHs, the molecular emission process, molecular anharmonicity, and the vibrational quasi-continuum. Extensive graphs, diagrams, and sample spectra are provided, and the interstellar emission bands are attributed to PAHs with 20-30 C atoms on the basis of the observed 3.3/3.4-micron intensity ratios.

  4. The formation of interstellar jets

    Science.gov (United States)

    Tenorio-Tagle, G.; Canto, J.; Rozyczka, M.

    1988-01-01

    The formation of interstellar jets by convergence of supersonic conical flows and the further dynamical evolution of these jets are investigated theoretically by means of numerical simulations. The results are presented in extensive graphs and characterized in detail. Strong radiative cooling is shown to result in jets with Mach numbers 2.5-29 propagating to lengths 50-100 times their original widths, with condensation of swept-up interstellar matter at Mach 5 or greater. The characteristics of so-called molecular outflows are well reproduced by the simulations of low-Mach-number and quasi-adiabatic jets.

  5. Remarks on the observability of single beacon underwater navigation

    DEFF Research Database (Denmark)

    Jouffroy, Jerome; Ross, Andrew

    This paper contributes a simple and intuitive result in the analysis of underwater navigation using a single ranging beacon. This analysis should help with the design of small and lightweight underwater vehicles by reducing the amount of instrumentation required for accurate navigation. The concept...

  6. Long Shelf Life of a Lyophilized DNA Aptamer Beacon Assay.

    Science.gov (United States)

    Bruno, John G

    2017-03-01

    An aptamer beacon previously developed to detect C-telopeptide (CTx) from human bone collagen breakdown was lyophilized and shown to give a "lights on" concentration-dependent spectral fluorescence response essentially identical to that of the fresh reagent despite storage in a dark dry environment for the past 5.5 years.

  7. Remarks on the observability of single beacon underwater navigation

    DEFF Research Database (Denmark)

    Jouffroy, Jerome; Ross, Andrew

    This paper contributes a simple and intuitive result in the analysis of underwater navigation using a single ranging beacon. This analysis should help with the design of small and lightweight underwater vehicles by reducing the amount of instrumentation required for accurate navigation. The concept...

  8. Exploration of Adaptive Beaconing for Efficient Intervehicle Safety Communication

    NARCIS (Netherlands)

    Schmidt, Robert K.; Leinmüller, Tim; Schoch, Elmar; Kargl, Frank; Schäfer, Günther

    2010-01-01

    In the future intervehicle communication will make driving safer, easier, and more comfortable. As a cornerstone of the system, vehicles need to be aware of other vehicles in the vicinity. This cooperative awareness is achieved by beaconing, the exchange of periodic single-hop broadcast messages tha

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

    Science.gov (United States)

    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.

  10. On the question of interstellar travel

    Science.gov (United States)

    Wolfe, J. H.

    1985-01-01

    Arguments are presented which show that motives for interstellar travel by advanced technological civilizations based on an extrapolation of earth's history may be quite invalid. In addition, it is proposed that interstellar travel is so enormously expensive and perhaps so hazardous, that advanced civilizations do not engage in such practices because of the ease of information transfer via interstellar communication.

  11. Experimental interstellar organic chemistry - Preliminary findings

    Science.gov (United States)

    Khare, B. N.; Sagan, C.

    1973-01-01

    Review of the results of some explicit experimental simulation of interstellar organic chemistry consisting in low-temperature high-vacuum UV irradiation of condensed simple gases known or suspected to be present in the interstellar medium. The results include the finding that acetonitrile may be present in the interstellar medium. The implication of this and other findings are discussed.

  12. Experimental interstellar organic chemistry - Preliminary findings

    Science.gov (United States)

    Khare, B. N.; Sagan, C.

    1973-01-01

    Review of the results of some explicit experimental simulation of interstellar organic chemistry consisting in low-temperature high-vacuum UV irradiation of condensed simple gases known or suspected to be present in the interstellar medium. The results include the finding that acetonitrile may be present in the interstellar medium. The implication of this and other findings are discussed.

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

    Directory of Open Access Journals (Sweden)

    Yuan Zhuang

    2016-04-01

    Full Text Available 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

  14. Interstellar Aldehydes and their corresponding Reduced Alcohols: Interstellar Propanol?

    Science.gov (United States)

    Etim, Emmanuel; Chakrabarti, Sandip Kumar; Das, Ankan; Gorai, Prasanta; Arunan, Elangannan

    2016-07-01

    There is a well-defined trend of aldehydes and their corresponding reduced alcohols among the known interstellar molecules; methanal (CH_2O) and methanol (CH_3OH); ethenone (C_2H_2O) and vinyl alcohol (CH_2CHOH); ethanal (C_2H_4O) and ethanol(C_2H_5OH); glycolaldehyde (C_2H_4O_2) and ethylene glycol(C_2H_6O_2). The reduced alcohol of propanal (CH_3CH_2CHO) which is propanol (CH_3CH_2CH_2OH) has not yet been observed but its isomer; ethyl methyl ether (CH_3CH_2OCH_3) is a known interstellar molecule. In this article, different studies are carried out in investigating the trend between aldehydes and their corresponding reduced alcohols and the deviation from the trend. Kinetically and with respect to the formation route, alcohols could have been produced from their corresponding reduced aldehydes via two successive hydrogen additions. This is plausible because of (a) the unquestionable high abundance of hydrogen, (b) presence of energy sources within some of the molecular clouds and (c) the ease at which successive hydrogen addition reaction occurs. In terms of stability, the observed alcohols are thermodynamically favorable as compared to their isomers. Regarding the formation process, the hydrogen addition reactions are believed to proceed on the surface of the interstellar grains which leads to the effect of interstellar hydrogen bonding. From the studies, propanol and propan-2-ol are found to be more strongly attached to the surface of the interstellar dust grains which affects its overall gas phase abundance as compared to its isomer ethyl methyl ether which has been observed.

  15. BEACON: automated tool for Bacterial GEnome Annotation ComparisON

    KAUST Repository

    Kalkatawi, Manal Matoq Saeed

    2015-08-18

    Background Genome annotation is one way of summarizing the existing knowledge about genomic characteristics of an organism. There has been an increased interest during the last several decades in computer-based structural and functional genome annotation. Many methods for this purpose have been developed for eukaryotes and prokaryotes. Our study focuses on comparison of functional annotations of prokaryotic genomes. To the best of our knowledge there is no fully automated system for detailed comparison of functional genome annotations generated by different annotation methods (AMs). Results The presence of many AMs and development of new ones introduce needs to: a/ compare different annotations for a single genome, and b/ generate annotation by combining individual ones. To address these issues we developed an Automated Tool for Bacterial GEnome Annotation ComparisON (BEACON) that benefits both AM developers and annotation analysers. BEACON provides detailed comparison of gene function annotations of prokaryotic genomes obtained by different AMs and generates extended annotations through combination of individual ones. For the illustration of BEACON’s utility, we provide a comparison analysis of multiple different annotations generated for four genomes and show on these examples that the extended annotation can increase the number of genes annotated by putative functions up to 27 %, while the number of genes without any function assignment is reduced. Conclusions We developed BEACON, a fast tool for an automated and a systematic comparison of different annotations of single genomes. The extended annotation assigns putative functions to many genes with unknown functions. BEACON is available under GNU General Public License version 3.0 and is accessible at: http://www.cbrc.kaust.edu.sa/BEACON/

  16. Herschel observations of interstellar chloronium

    NARCIS (Netherlands)

    Neufeld, David A.; Roueff, Evelyne; Snell, Ronald L.; Lis, Dariusz; Benz, Arnold O.; Bruderer, Simon; Black, John H.; De Luca, Massimo; Gerin, Maryvonne; Goldsmith, Paul F.; Gupta, Harshal; Indriolo, Nick; Le Bourlot, Jacques; Le Petit, Franck; Larsson, Bengt; Melnick, Gary J.; Menten, Karl M.; Monje, Raquel; Nagy, Zsofia; Phillips, Thomas G.; Sandqvist, Aage; Sonnentrucker, Paule; van der Tak, Floris; Wolfire, Mark G.

    2012-01-01

    Using the Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared, we have observed parachloronium (H2Cl+) toward six sources in the Galaxy. We detected interstellar chloronium absorption in foreground molecular clouds along the sight lines to the bright submillimeter continuum sourc

  17. Stardust Interstellar Preliminary Examination (ISPE)

    Science.gov (United States)

    Westphal, A. J.; Allen, C.; Bajt, S.; Basset, R.; Bastien, R.; Bechtel, H.; Bleuet, P.; Borg, J.; Brenker F.; Bridges, J.

    2009-01-01

    In January 2006 the Stardust sample return capsule returned to Earth bearing the first solid samples from a primitive solar system body, C omet 81P/Wild2, and a collector dedicated to the capture and return o f contemporary interstellar dust. Both collectors were approximately 0.1m(exp 2) in area and were composed of aerogel tiles (85% of the co llecting area) and aluminum foils. The Stardust Interstellar Dust Col lector (SIDC) was exposed to the interstellar dust stream for a total exposure factor of 20 m(exp 2-) day during two periods before the co metary encounter. The Stardust Interstellar Preliminary Examination ( ISPE) is a three-year effort to characterize the collection using no ndestructive techniques. The ISPE consists of six interdependent proj ects: (1) Candidate identification through automated digital microsco py and a massively distributed, calibrated search (2) Candidate extr action and photodocumentation (3) Characterization of candidates thro ugh synchrotronbased FourierTranform Infrared Spectroscopy (FTIR), S canning XRay Fluoresence Microscopy (SXRF), and Scanning Transmission Xray Microscopy (STXM) (4) Search for and analysis of craters in f oils through FESEM scanning, Auger Spectroscopy and synchrotronbased Photoemission Electron Microscopy (PEEM) (5) Modeling of interstell ar dust transport in the solar system (6) Laboratory simulations of h ypervelocity dust impacts into the collecting media

  18. Physical processes in the interstellar medium

    CERN Document Server

    Spitzer, Lyman

    2008-01-01

    Physical Processes in the Interstellar Medium discusses the nature of interstellar matter, with a strong emphasis on basic physical principles, and summarizes the present state of knowledge about the interstellar medium by providing the latest observational data. Physics and chemistry of the interstellar medium are treated, with frequent references to observational results. The overall equilibrium and dynamical state of the interstellar gas are described, with discussions of explosions produced by star birth and star death and the initial phases of cloud collapse leading to star formation.

  19. The Sun's dusty interstellar environment

    Science.gov (United States)

    Sterken, Veerle

    2016-07-01

    The Sun's dusty interstellar environment Interstellar dust from our immediate interstellar neighborhood travels through the solar system at speeds of ca. 26 km/s: the relative speed of the solar system with respect to the local interstellar cloud. On its way, its trajectories are altered by several forces like the solar radiation pressure force and Lorentz force. The latter is due to the charged dust particles that fly through the interplanetary magnetic field. These trajectories differ per particle type and size and lead to varying fluxes and directions of the flow inside of the solar system that depend on location but also on phase in the solar cycle. Hence, these fluxes and directions depend strongly on the configuration of the inner regions and outer regions of the heliosphere. Several missions have measured this dust in the solar system directly. The Ulysses dust detector data encompasses 16 years of intestellar dust fluxes and approximate directions, Stardust captured returned to Earth a few of these particles sucessfully, and finally the Cassini dust detector allowed for compositional information to be obtained from the impacts on the instrument. In this talk, we give an overview of the current status of interstellar dust research through the measurements made inside of the solar system, and we put them in perspective to the knowledge obtained from more classical astronomical means. In special, we focus on the interaction of the dust with the interplanetary magnetic field, and on what we learn about the dust (and the fields) by comparing the available dust data to computer simulations of dust trajectories. Finally, we synthesize the different methods of observation, their results, and give a preview on new research opportunities in the coming year(s).

  20. PAHs in Translucent Interstellar Clouds

    Science.gov (United States)

    Salama, Farid; Galazutdinov, G.; Krelowski, J.; Biennier, L.; Beletsky, Y.; Song, I.

    2011-05-01

    We discuss the proposal of relating the origin of some of the diffuse interstellar bands (DIBs) to neutral polycyclic aromatic hydrocarbons (PAHs) present in translucent interstellar clouds. The spectra of several cold, isolated gas-phase PAHs have been measured in the laboratory under experimental conditions that mimic the interstellar conditions and are compared with an extensive set of astronomical spectra of reddened, early type stars. This comparison provides - for the first time - accurate upper limits for the abundances of specific PAH molecules along specific lines-of-sight. Something that is not attainable from IR observations alone. The comparison of these unique laboratory data with high resolution, high S/N ratio astronomical observations leads to two major findings: (1) a finding specific to the individual molecules that were probed in this study and, which leads to the clear and unambiguous conclusion that the abundance of these specific neutral PAHs must be very low in the individual translucent interstellar clouds that were probed in this survey (PAH features remain below the level of detection) and, (2) a general finding that neutral PAHs exhibit intrinsic band profiles that are similar to the profile of the narrow DIBs indicating that the carriers of the narrow DIBs must have close molecular structure and characteristics. This study is the first quantitative survey of neutral PAHs in the optical range and it opens the way for unambiguous quantitative searches of PAHs in a variety of interstellar and circumstellar environments. // Reference: F. Salama et al. (2011) ApJ. 728 (1), 154 // Acknowledgements: F.S. acknowledges the support of the NASA's Space Mission Directorate APRA Program. J.K. acknowledges the financial support of the Polish State (grant N203 012 32/1550). The authors are deeply grateful to the ESO archive as well as to the ESO staff members for their active support.

  1. Single and multiple molecular beacon probes for DNA hybridization studies on a silica glass surface

    Science.gov (United States)

    Fang, Xiaohong; Liu, Xiaojing; Tan, Weihong

    1999-05-01

    Surface immobilizable molecular beacons have been developed for DNA hybridization studies on a silica glass plate. Molecular beacons are a new class of oligonucleotide probes that have a loop-and-stem structure with a fluorophore and a quencher attached to the two ends of the stem. They only emit intense fluorescence when hybridize to their target molecules. This provides an excellent selectivity for the detection of DNA molecules. We have designed biotinylated molecular beacons which can be immobilized onto a solid surface. The molecular beacon is synthesized using DABCYL as the quencher and an optical stable dye, tetramethylrhodamine, as the fluorophore. Mass spectrometry is used to confirm the synthesized molecular beacon. The molecular beacons have been immobilized onto a silica surface through biotin-avidin binding. The surface immobilized molecular beacons have been used for the detection of target DNA with subnanomolar analytical sensitivity. have also immobilized two different molecular beacons on a silica surface in spatially resolved microscopic regions. The hybridization study of these two different molecular beacon probes has shown excellent selectivity for their target sequences. The newly designed molecular beacons are intended for DNA molecular interaction studies at an interface and for the development of ultrasensitive DNA sensors for a variety of applications including disease diagnosis, disease mechanism studies, new drug development, and in the investigation of molecular interactions between DNA molecules and other interesting biomolecules.

  2. Interstellar dust. Evidence for interstellar origin of seven dust particles collected by the Stardust spacecraft.

    Science.gov (United States)

    Westphal, Andrew J; Stroud, Rhonda M; Bechtel, Hans A; Brenker, Frank E; Butterworth, Anna L; Flynn, George J; Frank, David R; Gainsforth, Zack; Hillier, Jon K; Postberg, Frank; Simionovici, Alexandre S; Sterken, Veerle J; Nittler, Larry R; Allen, Carlton; Anderson, David; Ansari, Asna; Bajt, Saša; Bastien, Ron K; Bassim, Nabil; Bridges, John; Brownlee, Donald E; Burchell, Mark; Burghammer, Manfred; Changela, Hitesh; Cloetens, Peter; Davis, Andrew M; Doll, Ryan; Floss, Christine; Grün, Eberhard; Heck, Philipp R; Hoppe, Peter; Hudson, Bruce; Huth, Joachim; Kearsley, Anton; King, Ashley J; Lai, Barry; Leitner, Jan; Lemelle, Laurence; Leonard, Ariel; Leroux, Hugues; Lettieri, Robert; Marchant, William; Ogliore, Ryan; Ong, Wei Jia; Price, Mark C; Sandford, Scott A; Sans Tresseras, Juan-Angel; Schmitz, Sylvia; Schoonjans, Tom; Schreiber, Kate; Silversmit, Geert; Solé, Vicente A; Srama, Ralf; Stadermann, Frank; Stephan, Thomas; Stodolna, Julien; Sutton, Stephen; Trieloff, Mario; Tsou, Peter; Tyliszczak, Tolek; Vekemans, Bart; Vincze, Laszlo; Von Korff, Joshua; Wordsworth, Naomi; Zevin, Daniel; Zolensky, Michael E

    2014-08-15

    Seven particles captured by the Stardust Interstellar Dust Collector and returned to Earth for laboratory analysis have features consistent with an origin in the contemporary interstellar dust stream. More than 50 spacecraft debris particles were also identified. The interstellar dust candidates are readily distinguished from debris impacts on the basis of elemental composition and/or impact trajectory. The seven candidate interstellar particles are diverse in elemental composition, crystal structure, and size. The presence of crystalline grains and multiple iron-bearing phases, including sulfide, in some particles indicates that individual interstellar particles diverge from any one representative model of interstellar dust inferred from astronomical observations and theory.

  3. Design of Radio Beacon for Spacecraft-Memory Localization

    Directory of Open Access Journals (Sweden)

    Xiansheng Zhang

    2013-09-01

    Full Text Available With the development of space technology and more and more space experiments, it has brought forward higher requests for memory of hard-recovered solid-state recorders. Therefore, Recovery of the memory becomes more important. Aiming at the disadvantages of present ways of recycling, we introduce a real-time GPS positioning wireless beacon can be applied on memory recovery. This paper introduces the principle of the system, circuit, and the function that can realized. Experimental results show that the beacon in a static environment and dynamic environment had a good performance in GPS positioning, and a high positioning accuracy. During Signal transmission, the receivers can received the raw GPS signal without error and can depict the running track of memory.

  4. iBeacon-perustaiset maamerkit sisätilapaikannuksessa

    OpenAIRE

    2015-01-01

    Tämän opinnäytetyön aihe saatiin HAMKin Älykkäät palvelut MATEC-tutkimusryhmästä. MATECssa on käynnissä koko vuoden kestävä projekti, Itsenäistä liikkumista sujuvoittavat iBeacon-tienlöytämisratkaisut (ILSI), minkä osana tämä työ toteutettiin. Projektissa haettiin mahdollisia ratkaisu-ja, käyttäen iBeacon-teknologiaa, jonka avulla voidaan helpottaa sokeiden ihmisten itsenäistä selviytymistä erilaisissa sisätilaympäristöissä. Työn tarkoituksena oli luoda älypuhelinsovellus Applen iOS-alust...

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

    Energy Technology Data Exchange (ETDEWEB)

    Amro, H; Chetty, I; Gordon, J; Wen, N [Henry Ford Health System, Detroit, MI (United States)

    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

    Science.gov (United States)

    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

    Science.gov (United States)

    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. Depolarization canals and interstellar turbulence

    CERN Document Server

    Fletcher, A; Fletcher, Andrew; Shukurov, Anvar

    2006-01-01

    Recent radio polarization observations have revealed a plethora of unexpected features in the polarized Galactic radio background that arise from propagation effects in the random (turbulent) interstellar medium. The canals are especially striking among them, a random network of very dark, narrow regions clearly visible in many directions against a bright polarized Galactic synchrotron background. There are no obvious physical structures in the ISM that may have caused the canals, and so they have been called Faraday ghosts. They evidently carry information about interstellar turbulence but only now is it becoming clear how this information can be extracted. Two theories for the origin of the canals have been proposed; both attribute the canals to Faraday rotation, but one invokes strong gradients in Faraday rotation in the sky plane (specifically, in a foreground Faraday screen) and the other only relies on line-of-sight effects (differential Faraday rotation). In this review we discuss the physical nature o...

  9. Interstellar Grains: 50 Years On

    CERN Document Server

    Wickramasinghe, N Chandra

    2011-01-01

    Our understanding of the nature of interstellar grains has evolved considerably over the past half century with the present author and Fred Hoyle being intimately involved at several key stages of progress. The currently fashionable graphite-silicate-organic grain model has all its essential aspects unequivocally traceable to original peer-reviewed publications by the author and/or Fred Hoyle. The prevailing reluctance to accept these clear-cut priorities may be linked to our further work that argued for interstellar grains and organics to have a biological provenance - a position perceived as heretical. The biological model, however, continues to provide a powerful unifying hypothesis for a vast amount of otherwise disconnected and disparate astronomical data.

  10. One Kilogram Interstellar Colony Mission

    Science.gov (United States)

    Mole, A.

    Small interstellar colony probes based on nanotechnology will become possible long before giant multi-generation ships become affordable. A beam generator and magnetic sail can accelerate a one kg probe to .1 c, braking via the interstellar field can decelerate it, and the field in a distant solar system can allow it to maneuver to an extrasolar planet. A heat shield is used for landing and nanobots emerge to build ever-larger robots and construct colony infrastructure. Humans can then be generated from genomes stored as data in computer memory. Technology is evolving towards these capabilities and should reach the required level in fifty years. The plan appears to be affordable, with the principal cost being the beam generator, estimated at $17 billion.

  11. Ionization in nearby interstellar gas

    Science.gov (United States)

    Frisch, P. C.; Welty, D. E.; York, D. G.; Fowler, J. R.

    1990-01-01

    Due to dielectric recombination, neutral magnesium represents an important tracer for the warm low-density gas around the solar system. New Mg I 2852 absorption-line data from IUE are presented, including detections in a few stars within 40 pc of the sun. The absence of detectable Mg I in Alpha CMa and other stars sets limits on the combined size and electron density of the interstellar cloud which gives rise to the local interstellar wind. For a cloud radius greater than 1 pc and density of 0.1/cu cm, the local cloud has a low fractional ionization, n(e)/n(tot) less than 0.05, if magnesium is undepleted, equilibrium conditions prevail, the cloud temperature is 11,750 K, and 80 percent of the magnesium in the sightline is Mg II.

  12. Ionization in nearby interstellar gas

    Energy Technology Data Exchange (ETDEWEB)

    Frisch, P.C.; Welty, D.E.; York, D.G.; Fowler, J.R. (Chicago Univ., IL (USA) New Mexico State Univ., Las Cruces (USA))

    1990-07-01

    Due to dielectric recombination, neutral magnesium represents an important tracer for the warm low-density gas around the solar system. New Mg I 2852 absorption-line data from IUE are presented, including detections in a few stars within 40 pc of the sun. The absence of detectable Mg I in Alpha CMa and other stars sets limits on the combined size and electron density of the interstellar cloud which gives rise to the local interstellar wind. For a cloud radius greater than 1 pc and density of 0.1/cu cm, the local cloud has a low fractional ionization, n(e)/n(tot) less than 0.05, if magnesium is undepleted, equilibrium conditions prevail, the cloud temperature is 11,750 K, and 80 percent of the magnesium in the sightline is Mg II. 85 refs.

  13. Representing culture in interstellar messages

    Science.gov (United States)

    Vakoch, Douglas A.

    2008-09-01

    As scholars involved with the Search for Extraterrestrial Intelligence (SETI) have contemplated how we might portray humankind in any messages sent to civilizations beyond Earth, one of the challenges they face is adequately representing the diversity of human cultures. For example, in a 2003 workshop in Paris sponsored by the SETI Institute, the International Academy of Astronautics (IAA) SETI Permanent Study Group, the International Society for the Arts, Sciences and Technology (ISAST), and the John Templeton Foundation, a varied group of artists, scientists, and scholars from the humanities considered how to encode notions of altruism in interstellar messages art_science/2003>. Though the group represented 10 countries, most were from Europe and North America, leading to the group's recommendation that subsequent discussions on the topic should include more globally representative perspectives. As a result, the IAA Study Group on Interstellar Message Construction and the SETI Institute sponsored a follow-up workshop in Santa Fe, New Mexico, USA in February 2005. The Santa Fe workshop brought together scholars from a range of disciplines including anthropology, archaeology, chemistry, communication science, philosophy, and psychology. Participants included scholars familiar with interstellar message design as well as specialists in cross-cultural research who had participated in the Symposium on Altruism in Cross-cultural Perspective, held just prior to the workshop during the annual conference of the Society for Cross-cultural Research . The workshop included discussion of how cultural understandings of altruism can complement and critique the more biologically based models of altruism proposed for interstellar messages at the 2003 Paris workshop. This paper, written by the chair of both the Paris and Santa Fe workshops, will explore the challenges of communicating concepts of altruism that draw on both biological and cultural models.

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

    Science.gov (United States)

    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 localization accuracy in environments with sparse beacon deployment.

  15. Caged molecular beacons: controlling nucleic acid hybridization with light.

    Science.gov (United States)

    Wang, Chunming; Zhu, Zhi; Song, Yanling; Lin, Hui; Yang, Chaoyong James; Tan, Weihong

    2011-05-28

    We have constructed a novel class of light-activatable caged molecular beacons (cMBs) that are caged by locking two stems with a photo-labile biomolecular interaction or covalent bond. With the cMBs, the nucleic acid hybridization process can be easily controlled with light, which offers the possibility for a high spatiotemporal resolution study of intracellular mRNAs. © The Royal Society of Chemistry 2011

  16. Aftermath of bustamante attack on genomic beacon service.

    Science.gov (United States)

    Aziz, Md Momin Al; Ghasemi, Reza; Waliullah, Md; Mohammed, Noman

    2017-07-26

    With the enormous need for federated eco-system for holding global genomic and clinical data, Global Alliance for Genomic and Health (GA4GH) has created an international website called beacon service which allows a researcher to find out whether a specific dataset can be utilized to his or her research beforehand. This simple webservice is quite useful as it allows queries like whether a certain position of a target chromosome has a specific nucleotide. However, the increased integration of individuals genomic data into clinical practice and research raised serious privacy concern. Though the answer of such queries are yes or no in Bacon network, it results in serious privacy implication as demonstrated in a recent work from Shringarpure and Bustamante. In their attack model, the authors demonstrated that with a limited number of queries, presence of an individual in any dataset can be determined. We propose two lightweight algorithms (based on randomized response) which captures the efficacy while preserving the privacy of the participants in a genomic beacon service. We also elaborate the strength and weakness of the attack by explaining some of their statistical and mathematical models using real world genomic database. We extend their experimental simulations for different adversarial assumptions and parameters. We experimentally evaluated the solutions on the original attack model with different parameters for better understanding of the privacy and utility tradeoffs provided by these two methods. Also, the statistical analysis further elaborates the different aspects of the prior attack which leads to a better risk management for the participants in a beacon service. The differentially private and lightweight solutions discussed here will make the attack much difficult to succeed while maintaining the fundamental motivation of beacon database network.

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

    Science.gov (United States)

    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,

  18. Photodissociation of interstellar N2

    CERN Document Server

    Li, Xiaohu; Visser, Ruud; Ubachs, Wim; Lewis, Brenton R; Gibson, Stephen T; van Dishoeck, Ewine F

    2013-01-01

    Molecular nitrogen is one of the key species in the chemistry of interstellar clouds and protoplanetary disks and the partitioning of nitrogen between N and N2 controls the formation of more complex prebiotic nitrogen-containing species. The aim of this work is to gain a better understanding of the interstellar N2 photodissociation processes based on recent detailed theoretical and experimental work and to provide accurate rates for use in chemical models. We simulated the full high-resolution line-by-line absorption + dissociation spectrum of N2 over the relevant 912-1000 \\AA\\ wavelength range, by using a quantum-mechanical model which solves the coupled-channels Schr\\"odinger equation. The simulated N2 spectra were compared with the absorption spectra of H2, H, CO, and dust to compute photodissociation rates in various radiation fields and shielding functions. The effects of the new rates in interstellar cloud models were illustrated for diffuse and translucent clouds, a dense photon dominated region and a ...

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

    Science.gov (United States)

    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.

  20. Cyclostationary Beacon for Assisting Spectrum Sensing in Opportunistic Spectrum Access

    Directory of Open Access Journals (Sweden)

    Thomas Kaiser

    2011-03-01

    Full Text Available Cognitive radio is a promising solution to the problem of spectrum scarcity by means of allowing secondary radio networks access the spectrum opportunistically. One of the most important issues in cognitive radio is how to detect existing over-the-air signals reliably. Not a few literatures have reported that signals could be detected via their inherent or embedded properties. However, this approach may not be reliable and flexible enough for all kinds of signals with different modulation types. In this paper, we propose a type of multitone beacon signal carrying cyclostationary signatures, which is able to enhance the reliability and efficiency of signal detection at low cost of spectrum overhead. This beacon not only can indicate the presence or absence of user signal but also can reveal some other information helpful to opportunistic spectrum access through the information bits carried on its cyclostationary signatures. It could be applied to device/network identification, indication of spectrum allocation and spectrum rendezvous, both for primary and secondary users. Based on our previous work reported in [1], the generation and detection algorithm of the beacon signal are extended with improved spectral efficiency. Performance is discussed with both computer simulation and testbed validation.

  1. Combining Magnetic and Electric Sails for Interstellar Deceleration

    Science.gov (United States)

    Perakis, Nikolaos; Hein, Andreas M.

    2016-07-01

    The main benefit of an interstellar mission is to carry out in-situ measurements within a target star system. To allow for extended in-situ measurements, the spacecraft needs to be decelerated. One of the currently most promising technologies for deceleration is the magnetic sail which uses the deflection of interstellar matter via a magnetic field to decelerate the spacecraft. However, while the magnetic sail is very efficient at high velocities, its performance decreases with lower speeds. This leads to deceleration durations of several decades depending on the spacecraft mass. Within the context of Project Dragonfly, initiated by the Initiative of Interstellar Studies (i4is), this paper proposes a novel concept for decelerating a spacecraft on an interstellar mission by combining a magnetic sail with an electric sail. Combining the sails compensates for each technologys shortcomings: A magnetic sail is more effective at higher velocities than the electric sail and vice versa. It is demonstrated that using both sails sequentially outperforms using only the magnetic or electric sail for various mission scenarios and velocity ranges, at a constant total spacecraft mass. For example, for decelerating from 5% c, to interplanetary velocities, a spacecraft with both sails needs about 29 years, whereas the electric sail alone would take 35 years and the magnetic sail about 40 years with a total spacecraft mass of 8250 kg. Furthermore, it is assessed how the combined deceleration system affects the optimal overall mission architecture for different spacecraft masses and cruising speeds. Future work would investigate how operating both systems in parallel instead of sequentially would affect its performance. Moreover, uncertainties in the density of interstellar matter and sail properties need to be explored.

  2. Laboratory spectroscopic studies of interstellar ice analogues

    OpenAIRE

    Puletti, F

    2014-01-01

    In recent years, the molecular chemistry in interstellar environments has proven to be far more complex than was initially expected. We live in a molecular universe that is rich with molecules formed both in the gas phase and on the surface of interstellar icy dust grains. Two important classes of interstellar molecules are sulphur-bearing species and complex organic molecules, i.e., molecules containing carbon and containing more than 6 atoms. The former are relevant because of their potenti...

  3. Physics of the interstellar and intergalactic medium

    CERN Document Server

    Draine, Bruce T

    2010-01-01

    This is a comprehensive and richly illustrated textbook on the astrophysics of the interstellar and intergalactic medium--the gas and dust, as well as the electromagnetic radiation, cosmic rays, and magnetic and gravitational fields, present between the stars in a galaxy and also between galaxies themselves. Topics include radiative processes across the electromagnetic spectrum; radiative transfer; ionization; heating and cooling; astrochemistry; interstellar dust; fluid dynamics, including ionization fronts and shock waves; cosmic rays; distribution and evolution of the interstellar medium

  4. Interstellar Extinction by Spheroidal Dust Grains

    OpenAIRE

    Gupta, Ranjan; Mukai, Tadashi; Vaidya, D. B.; Sen, Asoke K.; Okada, Yasuhiko

    2005-01-01

    Observations of interstellar extinction and polarization indicate that the interstellar medium consists of aligned non-spherical dust grains which show variation in the interstellar extinction curve for wavelengths ranging from NIR to UV. To model the extinction and polarization, one cannot use the Mie theory which assumes the grains as solid spheres. We have used a T-matrix based method for computing the extinction efficiencies of spheroidal silicate and graphite grains of different shapes (...

  5. Structure and Dynamics of the Interstellar Medium

    Science.gov (United States)

    Tenorio-Tagle, Guillermo; Moles, Mariano; Melnick, Jorge

    Here for the first time is a book that treats practically all aspects of modern research in interstellar matter astrophysics. 20 review articles and 40 carefully selected and refereed papers give a thorough overview of the field and convey the flavor of enthusiastic colloquium discussions to the reader. The book includes sections on: - Molecular clouds, star formation and HII regions - Mechanical energy sources - Discs, outflows, jets and HH objects - The Orion Nebula - The extragalactic interstellar medium - Interstellar matter at high galactic latitudes - The structure of the interstellar medium

  6. Deuterium enrichment of interstellar dusts

    Science.gov (United States)

    Das, Ankan; Chakrabarti, Sandip Kumar; Majumdar, Liton; Sahu, Dipen

    2016-07-01

    High abundance of some abundant and simple interstellar species could be explained by considering the chemistry that occurs on interstellar dusts. Because of its simplicity, the rate equation method is widely used to study the surface chemistry. However, because the recombination efficiency for the formation of any surface species is highly dependent on various physical and chemical parameters, the Monte Carlo method is best suited for addressing the randomness of the processes. We carry out Monte-Carlo simulation to study deuterium enrichment of interstellar grain mantle under various physical conditions. Based on the physical properties, various types of clouds are considered. We find that in diffuse cloud regions, very strong radiation fields persists and hardly a few layers of surface species are formed. In translucent cloud regions with a moderate radiation field, significant number of layers would be produced and surface coverage is mainly dominated by photo-dissociation products such as, C, CH_3, CH_2D, OH and OD. In the intermediate dense cloud regions (having number density of total hydrogen nuclei in all forms ˜2 × 10^4 cm^{-3}), water and methanol along with their deuterated derivatives are efficiently formed. For much higher density regions (˜10^6 cm^{-3}), water and methanol productions are suppressed but surface coverage of CO, CO_2, O_2, O_3 are dramatically increased. We find a very high degree of fractionation of water and methanol. Observational results support a high fractionation of methanol but surprisingly water fractionation is found to be low. This is in contradiction with our model results indicating alternative routes for de-fractionation of water.

  7. HERSCHEL OBSERVATIONS OF INTERSTELLAR CHLORONIUM

    Energy Technology Data Exchange (ETDEWEB)

    Neufeld, David A.; Indriolo, Nick [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 (United States); Roueff, Evelyne; Le Bourlot, Jacques; Le Petit, Franck [Observatoire de Paris-Meudon, LUTH UMR 8102, 5 Pl. Jules Janssen, F-92195 Meudon Cedex (France); Snell, Ronald L. [Astronomy Department, University of Massachusetts at Amherst, Amherst, MA 01003 (United States); Lis, Dariusz; Monje, Raquel; Phillips, Thomas G. [Astronomy Department, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Benz, Arnold O. [Institute of Astronomy, ETH Zurich, 8092 Zurich (Switzerland); Bruderer, Simon [Max Planck Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, D-85748, Garching (Germany); Black, John H.; Larsson, Bengt [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala (Sweden); De Luca, Massimo; Gerin, Maryvonne [LERMA, UMR 8112 du CNRS, Observatoire de Paris, Ecole Normale Superieure, UPMC and UCP (France); Goldsmith, Paul F.; Gupta, Harshal [JPL, California Institute of Technology, Pasadena, CA (United States); Melnick, Gary J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Menten, Karl M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Nagy, Zsofia [Kapteyn Astronomical Institute University of Groningen, Groningen (Netherlands); and others

    2012-03-20

    Using the Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared, we have observed para-chloronium (H{sub 2}Cl{sup +}) toward six sources in the Galaxy. We detected interstellar chloronium absorption in foreground molecular clouds along the sight lines to the bright submillimeter continuum sources Sgr A (+50 km s{sup -1} cloud) and W31C. Both the para-H{sup 35}{sub 2}Cl{sup +} and para-H{sup 37}{sub 2}Cl{sup +} isotopologues were detected, through observations of their 1{sub 11}-0{sub 00} transitions at rest frequencies of 485.42 and 484.23 GHz, respectively. For an assumed ortho-to-para ratio (OPR) of 3, the observed optical depths imply that chloronium accounts for {approx}4%-12% of chlorine nuclei in the gas phase. We detected interstellar chloronium emission from two sources in the Orion Molecular Cloud 1: the Orion Bar photodissociation region and the Orion South condensation. For an assumed OPR of 3 for chloronium, the observed emission line fluxes imply total beam-averaged column densities of {approx}2 Multiplication-Sign 10{sup 13} cm{sup -2} and {approx}1.2 Multiplication-Sign 10{sup 13} cm{sup -2}, respectively, for chloronium in these two sources. We obtained upper limits on the para-H{sup 35}{sub 2}Cl{sup +} line strengths toward H{sub 2} Peak 1 in the Orion Molecular cloud and toward the massive young star AFGL 2591. The chloronium abundances inferred in this study are typically at least a factor {approx}10 larger than the predictions of steady-state theoretical models for the chemistry of interstellar molecules containing chlorine. Several explanations for this discrepancy were investigated, but none has proven satisfactory, and thus the large observed abundances of chloronium remain puzzling.

  8. Grain Destruction in Interstellar Shocks

    OpenAIRE

    1995-01-01

    Interstellar shock waves can erode and destroy grains present in the shocked gas, primarily as the result of sputtering and grain-grain collisions. Uncertainties in current estimates of sputtering yields are reviewed. Results are presented for the simple case of sputtering of fast grains being stopped in cold gas. An upper limit is derived for sputtering of refractory grains in C-type MHD shocks: shock speeds $v_s \\gtrsim 50 \\kms$ are required for return of more than 30\\% of the silicate to t...

  9. A Search for Interstellar Pyrimidine

    CERN Document Server

    Kuan, Y J; Charnley, S B; Kisiel, Z; Ehrenfreund, P; Huang, H C; Kuan, Yi-Jehng; Yan, Chi-Hung; Charnley, Steven B.; Kisiel, Zbigniew; Ehrenfreund, Pascale; Huang, Hui-Chun

    2003-01-01

    We have searched three hot molecular cores for submillimeter emission from the nucleic acid building-block pyrimidine. We obtain upper limits to the total pyrimidine (beam-averaged) column densities towards Sgr B2(N), Orion KL and W51 e1/e2 of 1.7E+14 cm^{-2}, 2.4E+14 cm^{-2} and 3.4E+14 cm^{-2}, respectively. The associated upper limits to the pyrimidine fractional abundances lie in the range (0.3-3)E-10. Implications of this result for interstellar organic chemistry, and for the prospects of detecting nitrogen heterocycles in general, are briefly discussed.

  10. Discovery of Interstellar Heavy Water

    OpenAIRE

    Butner, H. M.; Charnley, S. B.; Ceccarelli, C.; Rodgers, S.D.; Pardo Carrión, Juan Ramón; Parise, B.; Cernicharo, José; Davis, G. R.

    2007-01-01

    We report the discovery of doubly deuterated water (D2O, heavy water) in the interstellar medium. Using the James Clerk Maxwell Telescope and the Caltech Submillimeter Observatory 10 m telescope, we detected the 1_10–1_01 transition of para-D2O at 316.7998 GHz in both absorption and emission toward the protostellar binary system IRAS 16293-2422. Assuming that the D2O exists primarily in the warm regions where water ices have been evaporated (i.e., in a "hot corino" environment), we determi...

  11. Development of a high-precision selenodetic coordinate system for the physical surface of the Moon based on LED beacons on its surface

    Science.gov (United States)

    Shirenin, A. M.; Mazurova, E. M.; Bagrov, A. V.

    2016-11-01

    The paper presents a mathematical algorithm for processing an array of angular measurements of light beacons on images of the lunar surface onboard a polar artificial lunar satellite (PALS) during the Luna-Glob mission and coordinate-time referencing of the PALS for the development of reference selenocentric coordinate systems. The algorithm makes it possible to obtain angular positions of point light beacons located on the surface of the Moon in selenocentric celestial coordinates. The operation of measurement systems that determine the position and orientation of the PALS during its active existence have been numerically simulated. Recommendations have been made for the optimal use of different types of measurements, including ground radio trajectory measurements, navigational star sensors based on the onboard star catalog, gyroscopic orientation systems, and space videos of the lunar surface.

  12. Molecular beacon probes combined with amplification by NASBA enable homogeneous, real-time detection of RNA

    NARCIS (Netherlands)

    Leone, G.; Schijndel, van H.; Gemen, van B.; Kramer, F.R.; Schoen, C.D.

    1998-01-01

    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 le

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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.

  15. Molecular beacon – tool for real time studying gene activity in stem cells

    DEFF Research Database (Denmark)

    Ilieva, Mirolyuba; Dufva, Martin

    and cancerogenesis. Molecular beacon technology is based on fluorescence resonance energy transfer (FRET) and the complementary pairing principles. These fluorescent molecular probes are highly specific and sensitive and are one important tool in in vitro diagnostics. Here molecular beacons are used to follow...

  16. Molecular beacon probes combined with amplification by NASBA enable homogeneous, real-time detection of RNA

    NARCIS (Netherlands)

    Leone, G.; Schijndel, van H.; Gemen, van B.; Kramer, F.R.; Schoen, C.D.

    1998-01-01

    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

  17. Crowdsourcing for Context: Regarding Privacy in Beacon Encounters via Contextual Integrity

    Directory of Open Access Journals (Sweden)

    Bello-Ogunu Emmanuel

    2016-07-01

    Full Text Available Research shows that context is important to the privacy perceptions associated with technology. With Bluetooth Low Energy beacons, one of the latest technologies for providing proximity and indoor tracking, the current identifiers that characterize a beacon are not sufficient for ordinary users to make informed privacy decisions about the location information that could be shared. One solution would be to have standardized category and privacy labels, produced by beacon providers or an independent third-party. An alternative solution is to find an approach driven by users, for users. In this paper, we propose a novel crowdsourcing based approach to introduce elements of context in beacon encounters.We demonstrate the effectiveness of this approach through a user study, where participants use a crowd-based mobile app designed to collect beacon category and privacy information as a scavenger hunt game. Results show that our approach was effective in helping users label beacons according to the specific context of a given beacon encounter, as well as the privacy perceptions associated with it. This labeling was done with an accuracy of 92%, and with an acceptance rate of 82% of all recommended crowd labels. Lastly, we conclusively show how crowdsourcing for context can be used towards a user-centric framework for privacy management during beacon encounters.

  18. 46 CFR 169.555 - Emergency position indicating radio beacon (EPIRB).

    Science.gov (United States)

    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 must...

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

    Science.gov (United States)

    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.

  20. 46 CFR 169.831 - Emergency position indicating radio beacon (EPIRB).

    Science.gov (United States)

    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 this...

  1. 46 CFR 169.744 - Emergency position indicating radio beacon (EPIRB).

    Science.gov (United States)

    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. ...

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

    Science.gov (United States)

    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…

  3. Beacon Editor: Capturing Signal Transduction Pathways Using the Systems Biology Graphical Notation Activity Flow Language.

    Science.gov (United States)

    Elmarakeby, Haitham; Arefiyan, Mostafa; Myers, Elijah; Li, Song; Grene, Ruth; Heath, Lenwood S

    2017-08-28

    The Beacon Editor is a cross-platform desktop application for the creation and modification of signal transduction pathways using the Systems Biology Graphical Notation Activity Flow (SBGN-AF) language. Prompted by biologists' requests for enhancements, the Beacon Editor includes numerous powerful features for the benefit of creation and presentation.

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

    Science.gov (United States)

    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…

  5. Molecular beacon probes combined with amplification by NASBA enable homogeneous, real-time detection of RNA

    NARCIS (Netherlands)

    Leone, G.; Schijndel, van H.; Gemen, van B.; Kramer, F.R.; Schoen, C.D.

    1998-01-01

    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 le

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

    Science.gov (United States)

    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.

  7. 46 CFR 28.150 - Emergency Position Indicating Radio Beacons (EPIRBs).

    Science.gov (United States)

    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)....

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

    Science.gov (United States)

    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

    Science.gov (United States)

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

    Science.gov (United States)

    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…

  11. Photodissociation of OH in interstellar clouds

    NARCIS (Netherlands)

    Dishoeck, van E.F.; Dalgarno, A.

    1984-01-01

    Calculations are presented of the lifetime of OH against photodissociation by the interstellar radiation field as a function of depth into interstellar clouds containing grains of various scattering properties. The effectiveness of the different photodissociation channels changes with depth into a c

  12. Directionality based Location Discovery Scheme Using Beacon Nodes with Transmission Capabilities throughout Sensor Network

    Directory of Open Access Journals (Sweden)

    Qinli An

    2013-06-01

    Full Text Available In this paper, we propose a range-free localization scheme for wireless sensor networks (WSNs using four beacon nodes(BNs equipped with a directional antenna with special transmission capabilities for sending wireless beacon signals throughout the sensor network. Each beacon node rotates with a constant angular speed and broadcasts its angular bearings. A sensor node can determine its location by listening to wireless transmissions from the four fixed beacon nodes. The proposed method is based on an angle-of-arrival estimation technique that does not increase the complexity or cost of construction of the sensor nodes. We present error analysis and the best positions of beacon nodes in the proposed method. Numerical results, obtained by simulating several scenarios, show that the algorithm can reach a good level of convergence.

  13. Measuring Transport Time of Mine Equipment in an Underground Mine Using a Bluetooth Beacon System

    Directory of Open Access Journals (Sweden)

    Jihoo Jung

    2016-12-01

    Full Text Available In this study, the time taken for mine haulage equipment to travel between destinations in an underground mine was measured and analyzed using a Bluetooth beacon system. In this system, Bluetooth beacons are attached to multiple points in an underground mine environment, and smartphones are mounted on mine equipment, such as haulage trucks, to collect transport time data. An underground limestone mine in Korea was selected to test the Bluetooth beacon system. The field experiments indicated that smartphones mounted on haulage trucks can recognize all Bluetooth beacons installed in the vicinity. The results also revealed that the Bluetooth beacon system can be used successfully in underground mines to quantitatively analyze transport times of haulage trucks going back and forth between loading and dumping points.

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

    Science.gov (United States)

    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. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Calculation on the Layout of A LED Optical Beacon with Three Sources%三光源 LED 光信标空间布局优化计算

    Institute of Scientific and Technical Information of China (English)

    王彩玲

    2015-01-01

    The optical beacon is an important position indicator in aviation , sea transportation and the sea life saving .With the need of the remote indication , the optical beacon with LED sources , owing to high brightness and luminous efficiency , is presented .Based on the established mathematical model of the light beam , the layout of the beacon with three lamp-houses is calculated theoretically , and the optimal layout , the ranges and the sizes of the blind zenos of the beacon are discussed .The results provide a theoretical guide for the structure design of the beacon essentially , and the method can be referred to layout of other multi-sources beacon .%在航空、海运及海上救生等各方面,光学信标是一种重要的光学指示手段。为了适应较远作用距离的要求,提出了采用高亮度、高发光效率的LED光源的光学信标。针对采用三光源光信标的空间布局进行了相关理论计算,建立光束空间数学模型,给出三光源的最佳空间布置,并计算出光信标盲区范围及盲区大小。本文的计算结果为光信标的结构设计提供必要的理论基础,其计算方法为多光源信标空间布局计算提供一定的参考。

  16. Detection of interstellar hydrogen peroxide

    CERN Document Server

    Bergman, P; Liseau, R; Larsson, B; Olofsson, H; Menten, K M; Güsten, R

    2011-01-01

    The molecular species hydrogen peroxide, HOOH, is likely to be a key ingredient in the oxygen and water chemistry in the interstellar medium. Our aim with this investigation is to determine how abundant HOOH is in the cloud core {\\rho} Oph A. By observing several transitions of HOOH in the (sub)millimeter regime we seek to identify the molecule and also to determine the excitation conditions through a multilevel excitation analysis. We have detected three spectral lines toward the SM1 position of {\\rho} Oph A at velocity-corrected frequencies that coincide very closely with those measured from laboratory spectroscopy of HOOH. A fourth line was detected at the 4{\\sigma} level. We also found through mapping observations that the HOOH emission extends (about 0.05 pc) over the densest part of the {\\rho} Oph A cloud core. We derive an abundance of HOOH relative to that of H_2 in the SM1 core of about 1\\times10^(-10). To our knowledge, this is the first reported detection of HOOH in the interstellar medium.

  17. Herschel observations of interstellar chloronium

    CERN Document Server

    Neufeld, David A; Snell, Ronald L; Lis, Dariusz; Benz, Arnold O; Bruderer, Simon; Black, John H; De Luca, Massimo; Gerin, Maryvonne; Goldsmith, Paul F; Gupta, Harshal; Indriolo, Nick; Bourlot, Jacques Le; Petit, Franck Le; Larsson, Bengt; Melnick, Gary J; Menten, Karl M; Monje, Raquel; Nagy, Zsofia; Phillips, Thomas G; Sandqvist, Aage; Sonnentrucker, Paule; van der Tak, Floris; Wolfire, Mark G

    2012-01-01

    Using the Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared (HIFI), we have observed para-chloronium (H2Cl+) toward six sources in the Galaxy. We detected interstellar chloronium absorption in foreground molecular clouds along the sight-lines to the bright submillimeter continuum sources Sgr A (+50 km/s cloud) and W31C. Both the para-H2-35Cl+ and para-H2-37Cl+ isotopologues were detected, through observations of their 1(11)-0(00) transitions at rest frequencies of 485.42 and 484.23 GHz, respectively. For an assumed ortho-to-para ratio of 3, the observed optical depths imply that chloronium accounts for ~ 4 - 12% of chlorine nuclei in the gas phase. We detected interstellar chloronium emission from two sources in the Orion Molecular Cloud 1: the Orion Bar photodissociation region and the Orion South condensation. For an assumed ortho-to-para ratio of 3 for chloronium, the observed emission line fluxes imply total beam-averaged column densities of ~ 2.0E+13 cm-2 and ~ 1.2E+13 cm-2, respect...

  18. On the Nature of Interstellar Grains

    Science.gov (United States)

    Hoyle, F.; Wickramasinghe, C.

    Data on interstellar extinction are interpreted to imply an identification of interstellar grains with naturally freeze-dried bacteria and algae. The total mass of such bacterial and algal cells in the galaxy is enormous, ~1040 g. The identification is based on Mie scattering calculations for an experimentally determined size distribution of bacteria. Agreement between our model calculations and astronomical data is remarkably precise over the wavelength intervals 1 μ-1 pigments. The strongest of the diffuse interstellar bands are provisionally assigned to carotenoid-chlorophyll pigment complexes such as exist in algae and pigmented bacteria. The λ2200 Å interstellar absorption feature could be due to `degraded' cellulose strands which form spherical graphitic particles, but could equally well be due to protein-lipid-nucleic acid complexes in bacteria and viruses. Interstellar extinction at wavelengths λ < 1800 Å could be due to scattering by virus particles.

  19. Realistic Detectability of Close Interstellar Comets

    CERN Document Server

    Cook, Nathaniel V; Granvik, Mikael; Stephens, Denise C

    2016-01-01

    During the planet formation process, billions of comets are created and ejected into interstellar space. The detection and characterization of such interstellar comets (also known as extra-solar planetesimals or extra-solar comets) would give us in situ information about the efficiency and properties of planet formation throughout the galaxy. However, no interstellar comets have ever been detected, despite the fact that their hyperbolic orbits would make them readily identifiable as unrelated to the solar system. Moro-Mart\\'in et al. 2009 have made a detailed and reasonable estimate of the properties of the interstellar comet population. We extend their estimates of detectability with a numerical model that allows us to consider "close" interstellar comets, e.g., those that come within the orbit of Jupiter. We include several constraints on a "detectable" object that allow for realistic estimates of the frequency of detections expected from the Large Synoptic Survey Telescope (LSST) and other surveys. The inf...

  20. Thermodynamics and Charging of Interstellar Iron Nanoparticles

    Science.gov (United States)

    Hensley, Brandon S.; Draine, B. T.

    2017-01-01

    Interstellar iron in the form of metallic iron nanoparticles may constitute a component of the interstellar dust. We compute the stability of iron nanoparticles to sublimation in the interstellar radiation field, finding that iron clusters can persist down to a radius of ≃4.5 Å, and perhaps smaller. We employ laboratory data on small iron clusters to compute the photoelectric yields as a function of grain size and the resulting grain charge distribution in various interstellar environments, finding that iron nanoparticles can acquire negative charges, particularly in regions with high gas temperatures and ionization fractions. If ≳10% of the interstellar iron is in the form of ultrasmall iron clusters, the photoelectric heating rate from dust may be increased by up to tens of percent relative to dust models with only carbonaceous and silicate grains.

  1. Thermodynamics and Charging of Interstellar Iron Nanoparticles

    CERN Document Server

    Hensley, Brandon S

    2016-01-01

    Interstellar iron in the form of metallic iron nanoparticles may constitute a component of the interstellar dust. We compute the stability of iron nanoparticles to sublimation in the interstellar radiation field, finding that iron clusters can persist down to a radius of $\\simeq 4.5\\,$\\AA, and perhaps smaller. We employ laboratory data on small iron clusters to compute the photoelectric yields as a function of grain size and the resulting grain charge distribution in various interstellar environments, finding that iron nanoparticles can acquire negative charges particularly in regions with high gas temperatures and ionization fractions. If $\\gtrsim 10\\%$ of the interstellar iron is in the form of ultrasmall iron clusters, the photoelectric heating rate from dust may be increased by up to tens of percent relative to dust models with only carbonaceous and silicate grains.

  2. Addressing Beacon re-identification attacks: quantification and mitigation of privacy risks.

    Science.gov (United States)

    Raisaro, Jean Louis; Tramèr, Florian; Ji, Zhanglong; Bu, Diyue; Zhao, Yongan; Carey, Knox; Lloyd, David; Sofia, Heidi; Baker, Dixie; Flicek, Paul; Shringarpure, Suyash; Bustamante, Carlos; Wang, Shuang; Jiang, Xiaoqian; Ohno-Machado, Lucila; Tang, Haixu; Wang, XiaoFeng; Hubaux, Jean-Pierre

    2017-02-20

    The Global Alliance for Genomics and Health (GA4GH) created the Beacon Project as a means of testing the willingness of data holders to share genetic data in the simplest technical context-a query for the presence of a specified nucleotide at a given position within a chromosome. Each participating site (or "beacon") is responsible for assuring that genomic data are exposed through the Beacon service only with the permission of the individual to whom the data pertains and in accordance with the GA4GH policy and standards.While recognizing the inference risks associated with large-scale data aggregation, and the fact that some beacons contain sensitive phenotypic associations that increase privacy risk, the GA4GH adjudged the risk of re-identification based on the binary yes/no allele-presence query responses as acceptable. However, recent work demonstrated that, given a beacon with specific characteristics (including relatively small sample size and an adversary who possesses an individual's whole genome sequence), the individual's membership in a beacon can be inferred through repeated queries for variants present in the individual's genome.In this paper, we propose three practical strategies for reducing re-identification risks in beacons. The first two strategies manipulate the beacon such that the presence of rare alleles is obscured; the third strategy budgets the number of accesses per user for each individual genome. Using a beacon containing data from the 1000 Genomes Project, we demonstrate that the proposed strategies can effectively reduce re-identification risk in beacon-like datasets. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association.

  3. Power sources for search and rescue 406 MHz beacons

    Science.gov (United States)

    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.

  4. Deep Sea AUV Navigation Using Multiple Acoustic Beacons

    Institute of Scientific and Technical Information of China (English)

    冀大雄; 宋伟; 赵宏宇; 刘健

    2016-01-01

    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.

  5. Beacon Hill公司的水彩系列

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Beacon Hill's公司最新的水彩系列有多种不同的颜色变化,跨度从微妙的柔和的中性色彩一直到充满异国情调的色彩。为了让客户更好地体验到这种水彩的感觉,他们采用了半透明色调的颜料绘制图案。

  6. Deep sea AUV navigation using multiple acoustic beacons

    Science.gov (United States)

    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.

  7. Molecular Beacon CNT-based Detection of SNPs

    Science.gov (United States)

    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.

  8. Polarimetry of the Interstellar Medium

    Science.gov (United States)

    Sandford, Scott; Witteborn, Fred C. (Technical Monitor)

    1995-01-01

    The talk will review what is known about the composition of ices and organics in the dense and diffuse interstellar media (ISM). Mixed molecular ices make up a significant fraction of the solid materials in dense molecular clouds and it is now known that thermal and radiation processing of these ices results in the production of more complex organic species, some of which may survive transport into forming stellar systems and the diffuse ISM. Molecular species identified in interstellar ices include H2O, CH3OH, CO, CH4, CO2, and somewhat surprisingly, H2. Theoretical and laboratory studies of the processing of interstellar analog ices containing these species indicate that species like HCO, H2CO, CH3, and NH3 are readily made and should also be present. The irradiation of mixed molecular ices containing these species, when followed by warming, leads to the production of a large variety of more complex species, including ethanol (CH3CH2OH), formamide (HC(=O)NH2), acetamide (CH3C(=O)NH2), nitriles or isonitriles (R-CN or R-NC hexamethylenetetramine (HMT; C6H12N4), a number of polymeric species related to polyoxymethylene [POM,(-CH2O-)n], and ketones {R-C(=O)-R'}. Spectral studies of dust in the diffuse ISM indicate the presence of fairly complex organics, some of which may be related to the organics produced in dense molecular clouds. Spectral comparisons indicate that the diffuse ISM organics may be quite similar to meteoritic kerogens, i.e. they may consist largely of aromatic moieties interlinked by short aliphatic bridges. Interestingly, recent evidence indicates that the galactic distribution of this material closely matches that of silicates, but does not correlate directly with visual extinction. This implies that a large fraction of the visual extinction is caused by a material other than these organics and silicates and that this other material has a significantly different distribution within the galaxy.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Ricardo Monroy-Contreras

    2011-01-01

    Full Text Available 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.

  11. Inversion of Ionospheric Electron Density from GPS Beacon Observations

    Institute of Scientific and Technical Information of China (English)

    ZouYu-hua; XuJi-sheng

    2003-01-01

    This paper studies the mathematical foundation of time-dependent three-dimensional (3-D) computerized ionospheric tomography (CIT) for reconstructing ionospheric electron density, N~, from ground-based GPS beacon observations. After simplifying the relation between N. and time,the time-dependent 3-D inversion in consideration is reduced to a 3-D tomography with incomplete projections. To see clearly the effects of the incompleteness on the quality of reconstruction under 3-D condition, the formula of 3-D parallelbeam tomogtTaphy is deduced theoretically. After establishing the mathematical foundation, simulations based on actual GPS ray paths with the help of the IRI-90 model are performed,and reasonable time-dependent 3-D distribution images of Ne are obtained when taking proper layout of the network and allowing variable resolutions. The quality of the reconstruction is rather good when compared with the images from the IRI-90 model directly. Therefore, results in this paper demonstrate that imaging of the ionospheric electron density distribution from GPS beacon observations is reasonable in theor yand feasible in practice.

  12. Inversion of Ionospheric Electron Density from GPS Beacon Observations

    Institute of Scientific and Technical Information of China (English)

    Zou Yu-hua; Xu Ji-sheng

    2003-01-01

    This paper studies the mathematical foundation of time-dependent three-dimensional (3-D) computerized ionospheric tomography (CIT) for reconstructing ionospheric electron density, Ne, from ground-based GPS beacon observations. After simplifying the relation between Ne and time,the time-dependent 3-D inversion in consideration is reduced to a 3-D tomography with incomplete projections.To see clearly the effects of the incompleteness on the quality of reconstruction under 3-D condition, the formula of 3-D parallel-beam tomography is deduced theoretically. After establishing the mathematical foundation, simulations based on actual GPS ray paths with the help of the IRI-90 model are performed,and reasonable time-dependent 3-D distribution images of Neare obtained when taking proper layout of the network and allowing variable resolutions. The quality of the reconstruction is rather good when compared with the images from the IRI-90 model directly. Therefore, results in this paper demon-strate that imaging of the ionospheric electron density distri-bution from GPS beacon observations is reasonable in theory and feasible in practice.

  13. Design and implementation of Bluetooth beacon in mobile payment system

    Science.gov (United States)

    Han, Tiantian; Ding, Lei

    2017-08-01

    The current line of payment means, mainly in the following ways, cash payment, credit card payment, WeChat Alipay sweep payment. There are many inconvenience in Cash payment, large amounts of cash inconvenience to carry, count the money to spend time and effort, true and false banknotes difficult to distinguish, ticket settlement easy to go wrong. Credit card payment is relatively time-consuming, and WeChat Alipay sweep payment need to sweep. Therefore, the design of a convenient, fast payment to meet the line to pay the demand is particularly important. Based on the characteristics of BLE Bluetooth wireless communication technology, this paper designs a kind of payment method based on Bluetooth beacon. Through the Bluetooth beacon broadcast consumption, consumers only need to open the relevant APP in the Android client, and you can get Bluetooth via mobile phone Bluetooth the amount of consumption of the standard broadcast, in accordance with the corresponding payment platform to complete the payment process, which pay less time to improve the efficiency of payment.

  14. Interstellar Dust Inside and Outside the Heliosphere

    CERN Document Server

    Krueger, Harald

    2008-01-01

    In the early 1990s, after its Jupiter flyby, the Ulysses spacecraft identified interstellar dust in the solar system. Since then the in-situ dust detector on board Ulysses continuously monitored interstellar grains with masses up to 10e-13 kg, penetrating deep into the solar system. While Ulysses measured the interstellar dust stream at high ecliptic latitudes between 3 and 5 AU, interstellar impactors were also measured with the in-situ dust detectors on board Cassini, Galileo and Helios, covering a heliocentric distance range between 0.3 and 3 AU in the ecliptic plane. The interstellar dust stream in the inner solar system is altered by the solar radiation pressure force, gravitational focussing and interaction of charged grains with the time varying interplanetary magnetic field. The grains act as tracers of the physical conditions in the local interstellar cloud (LIC). Our in-situ measurements imply the existence of a population of 'big' interstellar grains (up to 10e-13 kg) and a gas-to-dust-mass ratio i...

  15. Polarized Emission from Interstellar Dust

    CERN Document Server

    Vaillancourt, J E

    2006-01-01

    Observations of far-infrared (FIR) and submillimeter (SMM) polarized emission are used to study magnetic fields and dust grains in dense regions of the interstellar medium (ISM). These observations place constraints on models of molecular clouds, star-formation, grain alignment mechanisms, and grain size, shape, and composition. The FIR/SMM polarization is strongly dependent on wavelength. We have attributed this wavelength dependence to sampling different grain populations at different temperatures. To date, most observations of polarized emission have been in the densest regions of the ISM. Extending these observations to regions of the diffuse ISM, and to microwave frequencies, will provide additional tests of grain and alignment models. An understanding of polarized microwave emission from dust is key to an accurate measurement of the polarization of the cosmic microwave background. The microwave polarization spectrum will put limits on the contributions to polarized emission from spinning dust and vibrat...

  16. Discovery of Interstellar Hydrogen Fluoride

    Science.gov (United States)

    Neufeld, David A.; Zmuidzinas, Jonas; Schilke, Peter; Phillips, Thomas G.

    1997-01-01

    We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2-1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis of our model for the excitation of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a hydrogen fluoride abundance of approximately 3 x 10(exp -10) relative to H2. If the elemental abundance of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts for approximately 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed rapidly in exothermic reactions of atomic fluorine with either water or molecular hydrogen; thus, the measured HF abundance suggests a substantial depletion of fluorine onto dust grains. Similar conclusions regarding depletion have previously been reached for the case of chlorine in dense interstellar clouds. We also find evidence at a lower level of statistical significance (approximately 5 sigma) for an emission feature at the expected position of the 4(sub 32)-4(sub 23) 121.7219 micron line of water. The emission-line equivalent width of 0.5 nm for the water feature is consistent with the water abundance of 5 x 10(exp -6) relative to H2 that has been inferred previously from observations of the hot core of Sgr B2.

  17. Dual-channel detection of metallothioneins and mercury based on a mercury-mediated aptamer beacon using thymidine-mercury-thymidine complex as a quencher.

    Science.gov (United States)

    Chen, Si-Han; Wang, Yong-Sheng; Chen, Yun-Sheng; Tang, Xian; Cao, Jin-Xiu; Li, Ming-Hui; Wang, Xiao-Feng; Zhu, Yu-Feng; Huang, Yan-Qin

    2015-01-01

    A novel dual-channel strategy for the detection of metallothioneins (MTs) and Hg(2+) has been developed based on a mercury-mediated aptamer beacon (MAB) using thymidine-mercury-thymidine complex as a quencher for the first time. In the presence of Hg(2+), the T-rich oligonucleotide with a 6-carboxyfluorescein (TRO-FAM) can form an aptamer beacon via the formation of T-Hg(2+)-T base pairs, which results in a fluorescence quenching of the sensing system owing to the fluorescence resonance energy transfer (FRET) from the fluorophore of FAM to the terminated T-Hg(2+)-T base pair. The addition of MTs into this solution leads to the disruption of the T-Hg(2+)-T complex, resulting in an increase of the fluorescent signal of the system. In the optimizing condition, ΔF was directly proportional to the concentrations ranging from 5.63 nM to 0.275 μM for MTs, and 14.2 nM to 0.30 μM for Hg(2+) with the detection limits of 1.69 nM and 4.28 nM, respectively. The proposed dual-channel method avoids the label steps of a quencher in common molecular beacon strategies, without tedious procedure or the requirement of sophisticated equipment, and is rapid, inexpensive and sensitive.

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

    Science.gov (United States)

    Dave, Neeshma; Liu, Juewen

    2010-12-02

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. The use of nanocrystal quantum dot as fluorophore reporters in molecular beacon-based assays

    Science.gov (United States)

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-12-01

    The utilization of molecular beacon (MB) biosensor probes to detect nucleic acid targets has received enormous interest within the scientific community. This interest has been stimulated by the operational qualities of MB-based probes with respect to their unique sensitivity and specificity. The design of MB biosensors entails not only optimizing the sequence of the loop to hybridize with the nucleic acid target or optimization of the length of the stem to tune the sensitivity but also the selection of the appropriate fluorophore reporter to generate the signal transduction read-out upon hybridization of the probe with the target sequence. Traditional organic fluorescent dyes are mostly used for signal reporting in MB assays but their optical properties in comparison to semiconductor fluorescent quantum dot (Qdot) nanocrystals are at a disadvantage. This review highlights the progress made in exploiting Qdot as fluorophore reporters in MB-based assays with the aim of instigating further development in the field of Qdot-MB technology. The development reported to date indicates that unparalleled fluorescence signal reporting in MB-based assays can be achieved using well-constructed Qdot fluorophores.

  2. Quantitative rRNA-targeted solution-based hybridization assay using peptide nucleic acid molecular beacons.

    Science.gov (United States)

    Li, Xu; Morgenroth, Eberhard; Raskin, Lutgarde

    2008-12-01

    The potential of a solution-based hybridization assay using peptide nucleic acid (PNA) molecular beacon (MB) probes to quantify 16S rRNA of specific populations in RNA extracts of environmental samples was evaluated by designing PNA MB probes for the genera Dechloromonas and Dechlorosoma. In a kinetic study with 16S rRNA from pure cultures, the hybridization of PNA MB to target 16S rRNA exhibited a higher final hybridization signal and a lower apparent rate constant than the hybridizations to nontarget 16S rRNAs. A concentration of 10 mM NaCl in the hybridization buffer was found to be optimal for maximizing the difference between final hybridization signals from target and nontarget 16S rRNAs. Hybridization temperatures and formamide concentrations in hybridization buffers were optimized to minimize signals from hybridizations of PNA MB to nontarget 16S rRNAs. The detection limit of the PNA MB hybridization assay was determined to be 1.6 nM of 16S rRNA. To establish proof for the application of PNA MB hybridization assays in complex systems, target 16S rRNA from Dechlorosoma suillum was spiked at different levels to RNA isolated from an environmental (bioreactor) sample, and the PNA MB assay enabled effective quantification of the D. suillum RNA in this complex mixture. For another environmental sample, the quantitative results from the PNA MB hybridization assay were compared with those from clone libraries.

  3. High-throughput real-time assay based on molecular beacons for HIV-1 integrase 3'-processing reaction

    Institute of Scientific and Technical Information of China (English)

    Hong-qiu HE; Xiao-hui MA; Bin LIU; Xiao-yi ZHANG; Wei-zu CHEN; Cun-xin WANG; Shao-hui CHENG

    2007-01-01

    Aim: To develop a high-throughput real-time assay based on molecular beacons to monitor the integrase 3'-processing reaction in vitro and apply it to inhibitor screening.Methods: The recombinant human immunodeficiency virus (HIV)-1 integrase (IN) is incubated with a 38 mer oligonucleotide substrate, a sequence identical to the U5 end of HIV-1 long terminal repeats (LTR). Based on the fluores-cence properties of molecular beacons, the substrate is designed to form a stem-loop structure labeled with a fluorophore at the 5' end and a quencher at the 3'end.IN cleaves the terminal 3'-dinucleotide containing the quencher, resulting in an increase in fluorescence which can be monitored on a spectrofluorometer. To optimize this assay, tests were performed to investigate the effects of substrates, enzyme and the metal ion concentrations on the IN activity and optimal param-eters were obtained. Moreover, 2 IN inhibitors were employed to test the perfor-mance of this assay in antiviral compound screening.Results: The fluorescent intensity of the reaction mixture varies linearly with time and is proportional to the velocity of the 3'-processing reaction. Tests were performed and the results showed that the optimal rate was obtained for a reaction mixture containing 50 mg/L recom-binant HIV-1 IN, 400 nmol/L substrate, and 10 mmol/L Mn2+. The IN 3'-processing reaction under the optimal conditions showed a more than 18-fold increase in the fluorescence intensity compared to the enzyme-free control. The IC50 values of the IN inhibitors obtained in our assay were similar to the values obtained from a radiolabeled substrate assay.Conclusion: Our results demonstrated that this is a fast, reliable, and sensitive method to monitor HIV IN 3'-processing reaction and that it can be used for inhibitor screening.

  4. Interstellar Grains: Effect of Inclusions on Extinction

    CERN Document Server

    Katyal, Nisha; Vaidya, D B

    2011-01-01

    A composite dust grain model which simultaneously explains the observed interstellar extinction, polarization, IR emission and the abundance constraints, is required. We present a composite grain model, which is made up of a host silicate oblate spheroid and graphite inclusions. The interstellar extinction curve is evaluated in the spectral region 3.4-0.1$\\mu m$ using the extinction efficiencies of the composite spheroidal grains for three axial ratios. Extinction curves are computed using the discrete dipole approximation (DDA). The model curves are subsequently compared with the average observed interstellar extinction curve and with an extinction curve derived from the IUE catalogue data.

  5. Interstellar grains: Effect of inclusions on extinction

    Science.gov (United States)

    Katyal, N.; Gupta, R.; Vaidya, D. B.

    2011-10-01

    A composite dust grain model which simultaneously explains the observed interstellar extinction, polarization, IR emission and the abundance constraints, is required. We present a composite grain model, which is made up of a host silicate oblate spheroid and graphite inclusions. The interstellar extinction curve is evaluated in the spectral region 3.4-0.1 μm using the extinction efficiencies of composite spheroidal grains for three axial ratios. Extinction curves are computed using the discrete dipole approximation (DDA). The model curves are subsequently compared with the average observed interstellar extinction curve and with an extinction curve derived from the IUE catalogue data.

  6. Trajectories for a Near Term Mission to the Interstellar Medium

    Science.gov (United States)

    Arora, Nitin; Strange, Nathan; Alkalai, Leon

    2015-01-01

    Trajectories for rapid access to the interstellar medium (ISM) with a Kuiper Belt Object (KBO) flyby, launching between 2022 and 2030, are described. An impulsive-patched-conic broad search algorithm combined with a local optimizer is used for the trajectory computations. Two classes of trajectories, (1) with a powered Jupiter flyby and (2) with a perihelion maneuver, are studied and compared. Planetary flybys combined with leveraging maneuvers reduce launch C3 requirements (by factor of 2 or more) and help satisfy mission-phasing constraints. Low launch C3 combined with leveraging and a perihelion maneuver is found to be enabling for a near-term potential mission to the ISM.

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

    Science.gov (United States)

    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.

  8. An analysis of iBeacons and critical minimum distances in device placement

    OpenAIRE

    2014-01-01

    This project has been carried out in, and under the supervision of the Mobile Services Laboratory at the department of Communication Systems, KTH. The task was to explore the technical specifics of the iBeacon technology and its practical limitations in terms of reliability and device placement. In plain text; how close the beacons can be placed to allow for reliable isolation of the pertinent beacon. The main method of reaching the set goal was data capture at certain key positions around th...

  9. Detecting and Preventing Beacon Replay Attacks in Receiver-Initiated MAC Protocols for Energy Efficient WSNs

    DEFF Research Database (Denmark)

    Di Mauro, Alessio; Fafoutis, Xenofon; Mödersheim, Sebastian Alexander

    2013-01-01

    In receiver-initiated MAC protocols for Wireless Sensor Networks (WSNs), communication is initiated by the receiver of the data through beacons containing the receiver's identity. In this paper, we consider the case of a network intruder that captures and replays such beacons towards legitimate...... nodes, pretending to have a fake identity within the network. To prevent this attack we propose RAP, a challenge-response authentication protocol that is able to detect and prevent the beacon replay attack. The effectiveness of the protocol is formally verified using OFMC and ProVerif. Furthermore, we...

  10. Easy-to-Build Satellite Beacon Receiver for Propagation Experimentation at Millimeter Bands

    Directory of Open Access Journals (Sweden)

    F. Machado

    2014-04-01

    Full Text Available This paper describes the design and development of a digital satellite beacon receiver for propagation experimentation. Satellite beacons are frequently available for pointing large antennas, but such signals can be used for measuring rain attenuation and other phenomena as, for example, tropospheric scintillation. A fairly inexpensive beacon receiver has been built using off-the-shelf parts. This instrument is not at all bulky making it suitable for easy transportation. This article analyzes the receiver specifications, describes in detail its structure and presents some operational test results.

  11. Cosmocultural Evolution: Cosmic Motivation for Interstellar Travel?

    Science.gov (United States)

    Lupisella, M.

    Motivations for interstellar travel can vary widely from practical survival motivations to wider-ranging moral obligations to future generations. But it may also be fruitful to explore what, if any, "cosmic" relevance there may be regarding interstellar travel. Cosmocultural evolution can be defined as the coevolution of cosmos and culture, with cultural evolution playing an important and perhaps critical role in the overall evolution of the universe. Strong versions of cosmocultural evolution might suggest that cultural evolution may have unlimited potential as a cosmic force. In such a worldview, the advancement of cultural beings throughout the universe could have significant cosmic relevance, perhaps providing additional motivation for interstellar travel. This paper will explore some potential philosophical and policy implications for interstellar travel of a cosmocultural evolutionary perspective and other related concepts, including some from a recent NASA book, Cosmos and Culture: Cultural Evolution in a Cosmic Context.

  12. Physical Processes in the Interstellar Medium

    CERN Document Server

    Klessen, Ralf S

    2014-01-01

    Interstellar space is filled with a dilute mixture of charged particles, atoms, molecules and dust grains, called the interstellar medium (ISM). Understanding its physical properties and dynamical behavior is of pivotal importance to many areas of astronomy and astrophysics. Galaxy formation and evolution, the formation of stars, cosmic nucleosynthesis, the origin of large complex, prebiotic molecules and the abundance, structure and growth of dust grains which constitute the fundamental building blocks of planets, all these processes are intimately coupled to the physics of the interstellar medium. However, despite its importance, its structure and evolution is still not fully understood. Observations reveal that the interstellar medium is highly turbulent, consists of different chemical phases, and is characterized by complex structure on all resolvable spatial and temporal scales. Our current numerical and theoretical models describe it as a strongly coupled system that is far from equilibrium and where th...

  13. Silicate Composition of the Interstellar Medium

    CERN Document Server

    Fogerty, Shane; Watson, Dan M; Sargent, Benjamin A; Koch, Ingrid

    2016-01-01

    The composition of silicate dust in the diffuse interstellar medium and in protoplanetary disks around young stars informs our understanding of the processing and evolution of the dust grains leading up to planet formation. Analysis of the well-known 9.7{\\mu}m feature indicates that small amorphous silicate grains represent a significant fraction of interstellar dust and are also major components of protoplanetary disks. However, this feature is typically modelled assuming amorphous silicate dust of olivine and pyroxene stoichiometries. Here, we analyze interstellar dust with models of silicate dust that include non-stoichiometric amorphous silicate grains. Modelling the optical depth along lines of sight toward the extinguished objects Cyg OB2 No. 12 and {\\zeta} Ophiuchi, we find evidence for interstellar amorphous silicate dust with stoichiometry intermediate between olivine and pyroxene, which we simply refer to as "polivene." Finally, we compare these results to models of silicate emission from the Trapez...

  14. Physical Processes in the Interstellar Medium

    OpenAIRE

    2014-01-01

    Interstellar space is filled with a dilute mixture of charged particles, atoms, molecules and dust grains, called the interstellar medium (ISM). Understanding its physical properties and dynamical behavior is of pivotal importance to many areas of astronomy and astrophysics. Galaxy formation and evolution, the formation of stars, cosmic nucleosynthesis, the origin of large complex, prebiotic molecules and the abundance, structure and growth of dust grains which constitute the fundamental buil...

  15. The hydrogen coverage of interstellar PAHs

    Science.gov (United States)

    Tielens, A. G. G. M.; Allamandola, L. J.; Barker, J. R.; Cohen, M.

    1987-01-01

    The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a UV photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially dehydrogenated in regions with intense UV fields, while large PAHs (greater than or equal to 25 atoms) are expected to be completely hydrogenated in those regions. Because estimate of the carbon content of interstellar PAHs lie in the range of 20 to 25 carbon atoms, dehydrogenation is probably not very important. Because of the absence of other emission features besides the 11.3 micrometer feature in ground-based 8 to 13 micrometer spectra, it has been suggested that interstellar PAHs are partially dehydrogenated. However, IRAS 8 to 22 micrometer spectra of most sources that show strong 7.7 and 11.2 micrometer emission features also show a plateau of emission extending from about 11.3 to 14 micrometer. Like the 11.3 micrometer feature, this new feature is attributed to the CH out of plane bending mode in PAHs. This new feature shows that interstellar PAHs are not as dehydrogenated as estimated from ground-based 8 to 13 micrometer spectra. It also constrains the molecular structure of interstellar PAHs. In particular, it seems that very condensed PAHs, such as coronene and circumcoronene, dominate the interstellar PAH mixture as expected from stability arguments.

  16. Interstellar grain chemistry and organic molecules

    Science.gov (United States)

    Allamandola, L. J.; Sandford, S. A.

    1990-01-01

    The detection of prominant infrared absorption bands at 3250, 2170, 2138, 1670 and 1470 cm(-1) (3.08, 4.61, 4.677, 5.99 and 6.80 micron m) associated with molecular clouds show that mixed molecular (icy) grain mantles are an important component of the interstellar dust in the dense interstellar medium. These ices, which contain many organic molecules, may also be the production site of the more complex organic grain mantles detected in the diffuse interstellar medium. Theoretical calculations employing gas phase as well as grain surface reactions predict that the ices should be dominated only by the simple molecules H2O, H2CO, N2, CO, O2, NH3, CH4, possibly CH3OH, and their deuterated counterparts. However, spectroscopic observations in the 2500 to 1250 cm(-1)(4 to 8 micron m) range show substantial variation from source reactions alone. By comparing these astronomical spectra with the spectra of laboratory-produced analogs of interstellar ices, one can determine the composition and abundance of the materials frozen on the grains in dense clouds. Experiments are described in which the chemical evolution of an interstellar ice analog is determined during irradiation and subsequent warm-up. Particular attention is paid to the types of moderately complex organic materials produced during these experiments which are likely to be present in interstellar grains and cometary ices.

  17. Amino Acid Formation on Interstellar Dust Particles

    Science.gov (United States)

    Meierhenrich, U. J.; Munoz Caro, G. M.; Barbier, B.; Brack, A.; Thiemann, W.; Goesmann, F.; Rosenbauer, H.

    2003-04-01

    In the dense interstellar medium dust particles accrete ice layers of known molecular composition. In the diffuse interstellar medium these ice layers are subjected to energetic UV-irradiation. Here, photoreactions form complex organic molecules. The interstellar processes were recently successfully simulated in two laboratories. At NASA Ames Research Center three amino acids were detected in interstellar ice analogues [1], contemporaneously, our European team reported on the identification of 16 amino acids therein [2]. Amino acids are the molecular building blocks of proteins in living organisms. The identification of amino acids on the simulated icy surface of interstellar dust particles strongly supports the assumption that the precursor molecules of life were delivered from interstellar and interplanetary space via (micro-) meteorites and/or comets to the earyl Earth. The results shall be verified by the COSAC experiment onboard the ESA cometary mission Rosetta [3]. [1] M.P. Bernstein, J.P. Dworkin, S.A. Sandford, G.W. Cooper, L.J. Allamandola: itshape Nature \\upshape 416 (2002), 401-403. [2] G.M. Muñoz Caro, U.J. Meierhenrich, W.A. Schutte, B. Barbier, A. Arcones Sergovia, H. Rosenbauer, W.H.-P. Thiemann, A. Brack, J.M. Greenberg: itshape Nature \\upshape 416 (2002), 403-406. [3] U. Meierhenrich, W.H.-P. Thiemann, H. Rosenbauer: itshape Chirality \\upshape 11 (1999), 575-582.

  18. WSN中信标节点移动情况下的定位方法研究%Research on Localization Algorithm with Beacon Movement in Wireless Sensor Network

    Institute of Scientific and Technical Information of China (English)

    何文秀; 夏明; 赵小敏; 程荣; 陈庆章

    2011-01-01

    Localization is one of the basic theories and key technologies in wireless sensor network (WSN). However, in practical applications , the locations of some beacons would change due to various reasons after deployment, which leads to other unknown nodes rely on these beacons can not been accurately located. In order to solve the localization problems with beacons movement, this paper proposed an area division based beacon movement detection algorithm (AD-BMD), through two judgment processes to determine which beacon have moved, and set a coordinates confidence value for each beacon. In order to use moving beacons and unmoving beacons more reasonably, this paper also proposed a beacon movement detection based beacon optimal selection localization algorithm (BMD-BOS), through selecting beacons reasonably to calculate the position of unknown nodes. Experiment results show that AD-BMD has high correct rate and low error rate. Compared with LB and SSV, AD-BMD has better performance. The localization accuracy of BMD-BOS is much higher than N-BMD's and D-BMD's.%定位技术是无线传感器网络的基础理论和关键技术之一.在实际应用中,一些信标节点在部署以后其位置由于各种原因而会发生漂移,由此就使得依赖于这些信标节点来定位的其他节点将无法准确定位,或者产生很大定位误差.本文针对信标节点产生漂移情况下的节点定位问题,提出了一种基于区域划分的信标节点移动检测算法(AD-BMD),在区域划分的基础上,通过两次判定过程将移动的信标节点检测出来,并为每个信标设置了坐标可信度值.为合理利用移动的和未移动的信标节点,提出一种基于信标移动检测的信标择优定位算法(BMD-BOS),通过合理选择信标节点来对其它未知节点进行定位.实验结果证明,AD-BMD算法具有很高的检测正确率和较低错误率,检测效果好于LB和SSV方法.BMD-BOS算法的定位精度远远高于没有进行移

  19. Optimism

    Science.gov (United States)

    Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.

    2010-01-01

    Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998

  20. Seamless Guidance System Combining GPS, BLE Beacon, and NFC Technologies

    Directory of Open Access Journals (Sweden)

    Rung-Shiang Cheng

    2016-01-01

    Full Text Available Users rely increasingly on Location-Based Services (LBS and automated navigation/guidance systems nowadays. However, while such services are easily implemented in outdoor environments using Global Positioning System (GPS technology, a requirement still exists for accurate localization and guidance schemes in indoor settings. Accordingly, the present study proposes a system based on GPS, Bluetooth Low Energy (BLE beacons, and Near Field Communication (NFC technology. Through establishing graphic information and the design of algorithm, this study develops a guidance system for indoors and outdoors on smart phones, wishing to give user perfect smart life through this system. The proposed system is implemented on a smart phone and evaluated on a student campus environment. The experimental results confirm the ability of the proposed app to switch automatically from an outdoor mode to an indoor mode and to guide the user to requested target destination via the shortest possible route.

  1. Directional pattern measurement of the BRAMS beacon antenna system

    Science.gov (United States)

    Martínez Picar, A.; Marqué, C.; Anciaux, M.; Lamy, H.

    2015-01-01

    The typical methods for measuring antenna characteristics are mostly based on the use of remote transmitters or receivers. For antennas used in radio communications, calibrations are usually done on an antenna test stand using transmitters with known power output. In order to minimize the ground effects while performing measurements, it is necessary to place the transmitter or receiver high above ground with the aid of aircrafts. It is, however, necessary to determine precisely the coordinates of the airborne devices as well as to maintain high stability. This used to be excessively difficult to carry out, but recent advances in Unmanned Aerial Vehicle (UAV) technologies have brought a feasible option. In this paper, the results of using a low-cost system for measuring the directional pattern of BRAMS beacon antenna system based on an UAV are presented.

  2. Beacons of discovery the worldwide science of particle physics

    CERN Document Server

    International Committee for Future Accelerators (ICFA)

    2011-01-01

    To discover what our world is made of and how it works at the most fundamental level is the challenge of particle physics. The tools of particle physics—experiments at particle accelerators and underground laboratories, together with observations of space—bring opportunities for discovery never before within reach. Thousands of scientists from universities and laboratories around the world collaborate to design, build and use unique detectors and accelerators to explore the fundamental physics of matter, energy, space and time. Together, in a common world-wide program of discovery, they provide a deep understanding of the world around us and countless benefits to society. Beacons of Discovery presents a vision of the global science of particle physics at the dawn of a new light on the mystery and beauty of the universe.

  3. BEACON: A Summary Framework to Overcome Potential Reimbursement Hurdles.

    Science.gov (United States)

    Dunlop, William C N; Mullins, C Daniel; Pirk, Olaf; Goeree, Ron; Postma, Maarten J; Enstone, Ashley; Heron, Louise

    2016-10-01

    To provide a framework for addressing payers' criteria during the development of pharmaceuticals. A conceptual framework was presented to an international health economic expert panel for discussion. A structured literature search (from 2010 to May 2015), using the following databases in Ovid: Medline(®) and Medline(®) In-Process (PubMed), Embase (Ovid), EconLit (EBSCOhost) and the National Health Service Economic Evaluation Database (NHS EED), and a 'grey literature' search, were conducted to identify existing criteria from the payer perspective. The criteria assessed by existing frameworks and guidelines were collated; the most commonly reported criteria were considered for inclusion in the framework. A mnemonic was conceived as a memory aide to summarise these criteria. Overall, 41 publications were identified as potentially relevant to the objective. Following further screening, 26 were excluded upon full-text review on the basis of no framework presented (n = 13), redundancy (n = 11) or abstract only (n = 2). Frameworks that captured criteria developed for or utilised by the pharmaceutical industry (n = 5) and reimbursement guidance (n = 10) were reviewed. The most commonly identified criteria-unmet need/patient burden, safety, efficacy, quality-of-life outcomes, environment, evidence quality, budget impact and comparator-were incorporated into the summary framework. For ease of communication, the following mnemonic was developed: BEACON (Burden/target population, Environment, Affordability/value, Comparator, Outcomes, Number of studies/quality of evidence). The BEACON framework aims to capture the 'essence' of payer requirements by addressing the most commonly described criteria requested by payers regarding the introduction of a new pharmaceutical.

  4. Digital beacon receiver for ionospheric TEC measurement developed with GNU Radio

    Science.gov (United States)

    Yamamoto, M.

    2008-11-01

    A simple digital receiver named GNU Radio Beacon Receiver (GRBR) was developed for the satellite-ground beacon experiment to measure the ionospheric total electron content (TEC). The open-source software toolkit for the software defined radio, GNU Radio, is utilized to realize the basic function of the receiver and perform fast signal processing. The software is written in Python for a LINUX PC. The open-source hardware called Universal Software Radio Peripheral (USRP), which best matches the GNU Radio, is used as a front-end to acquire the satellite beacon signals of 150 and 400 MHz. The first experiment was successful as results from GRBR showed very good agreement to those from the co-located analog beacon receiver. Detailed design information and software codes are open at the URL http://www.rish.kyoto-u.ac.jp/digitalbeacon/.

  5. Multi-kW Uplink Fiber-Laser Beacon with Agile Signal Format Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Uplink Laser Beacons for deep-space communication, can benefit greatly from migration to the 1010-1030nm wavelengths, via use of Silicon-APDs on the spacecraft...

  6. High-throughput SNP genotyping: combining tag SNPs and molecular beacons

    CSIR Research Space (South Africa)

    Barreiro, LB

    2009-10-01

    Full Text Available In the last decade, molecular beacons have emerged to become a widely used tool in the multiplex typing of single nucleotide polymorphisms (SNPs). Improvements in detection technologies in instrumentation and chemistries to label these probes have...

  7. Tracking neuronal marker expression inside living differentiating cells using molecular beacons

    DEFF Research Database (Denmark)

    Ilieva, Mirolyuba; Della Vedova, Paolo; Hansen, Ole

    2013-01-01

    Monitoring gene expression is an important tool for elucidating mechanisms of cellular function. In order to monitor gene expression during nerve cell development, molecular beacon (MB) probes targeting markers representing different stages of neuronal differentiation were designed and synthesized...

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Multi-kW Uplink Fiber-Laser Beacon with Agile Signal Format Project

    Data.gov (United States)

    National Aeronautics and Space Administration —  Laser beacons with scalable powers are needed for ground to deep-space optical communication uplinks. They serve as absolute reference for tracking of...

  10. LDB: Localization with Directional Beacons for Sparse 3D Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Hanjiang Luo

    2010-01-01

    Full Text Available In this paper, we propose a novel distributed localization scheme LDB, a 3D localization scheme with directional beacons for Underwater Acoustic Sensor Networks (UWA-SNs. LDB localizes sensor nodes using an Autonomous Underwater Vehicle (AUV as a mobile beacon sender. Mounted with a directional transceiver which creates conical shaped directional acoustic beam, the AUV patrols over the 3D deployment volume with predefined trajectory sending beacons with constant interval towards the sensor nodes. By listening two or more beacons sent from the AUV, the nodes can localize themselves silently. Through theoretical analysis, we provide the upper bound of the estimation error of the scheme. We also evaluate the scheme by simulations and the results show that our scheme can achieve a high localization accuracy, even in sparse networks.

  11. Optimization

    CERN Document Server

    Pearce, Charles

    2009-01-01

    Focuses on mathematical structure, and on real-world applications. This book includes developments in several optimization-related topics such as decision theory, linear programming, turnpike theory, duality theory, convex analysis, and queuing theory.

  12. Characterization of Interstellar Organic Molecules

    Science.gov (United States)

    Gençaǧa, Deniz; Carbon, Duane F.; Knuth, Kevin H.

    2008-11-01

    Understanding the origins of life has been one of the greatest dreams throughout history. It is now known that star-forming regions contain complex organic molecules, known as Polycyclic Aromatic Hydrocarbons (PAHs), each of which has particular infrared spectral characteristics. By understanding which PAH species are found in specific star-forming regions, we can better understand the biochemistry that takes place in interstellar clouds. Identifying and classifying PAHs is not an easy task: we can only observe a single superposition of PAH spectra at any given astrophysical site, with the PAH species perhaps numbering in the hundreds or even thousands. This is a challenging source separation problem since we have only one observation composed of numerous mixed sources. However, it is made easier with the help of a library of hundreds of PAH spectra. In order to separate PAH molecules from their mixture, we need to identify the specific species and their unique concentrations that would provide the given mixture. We develop a Bayesian approach for this problem where sources are separated from their mixture by Metropolis Hastings algorithm. Separated PAH concentrations are provided with their error bars, illustrating the uncertainties involved in the estimation process. The approach is demonstrated on synthetic spectral mixtures using spectral resolutions from the Infrared Space Observatory (ISO). Performance of the method is tested for different noise levels.

  13. Interstellar Transfer of Planetary Microbiota

    Science.gov (United States)

    Wallis, Max K.; Wickramasinghe, N. C.

    Panspermia theories require the transport of micro-organisms in a viable form from one astronomical location to another. The evidence of material ejection from planetary surfaces, of dynamical orbit evolution and of potential survival on landing is setting a firm basis for interplanetary panspermia. Pathways for interstellar panspermia are less clear. We compare the direct route, whereby life-bearing planetary ejecta exit the solar system and risk radiation hazards en route to nearby stellar systems, and an indirect route whereby ejecta hitch a ride within the shielded environment of comets of the Edgeworth- Kuiper Belt that are subsequently expelled from the solar system. We identify solutions to the delivery problem. Delivery to fully-fledged planetary systems of either the direct ejecta or the ejecta borne by comets depends on dynamical capture and is of very low efficiency. However, delivery into a proto-planetary disc of an early solar-type nebula and into pre-stellar molecular clouds is effective, because the solid grains efficiently sputter the incoming material in hypervelocity collisions. The total mass of terrestrial fertile material delivered to nearby pre-stellar systems as the solar system moves through the galaxy is from kilogrammes up to a tonne. Subject to further study of bio-viability under irradiation and fragmenting collisions, a few kg of original grains and sputtered fragments could be sufficient to seed the planetary system with a wide range of solar system micro-organisms.

  14. The interstellar medium in galaxies

    CERN Document Server

    1997-01-01

    It has been more than five decades ago that Henk van de Hulst predicted the observability of the 21-cm line of neutral hydrogen (HI ). Since then use of the 21-cm line has greatly improved our knowledge in many fields and has been used for galactic structure studies, studies of the interstellar medium (ISM) in the Milky Way and other galaxies, studies of the mass distribution of the Milky Way and other galaxies, studies of spiral struc­ ture, studies of high velocity gas in the Milky Way and other galaxies, for measuring distances using the Tully-Fisher relation etc. Regarding studies of the ISM, there have been a number of instrumen­ tal developments over the past decade: large CCD's became available on optical telescopes, radio synthesis offered sensitive imaging capabilities, not only in the classical 21-cm HI line but also in the mm-transitions of CO and other molecules, and X-ray imaging capabilities became available to measure the hot component of the ISM. These developments meant that Milky Way was n...

  15. Rotational spectroscopy of interstellar PAHs

    CERN Document Server

    Ali-Haïmoud, Yacine

    2013-01-01

    Polycyclic aromatic hydrocarbons (PAHs) have long been part of the standard model of the interstellar medium, and are believed to play important roles in its physics and chemistry. Yet, up to now it has not been possible to identify any specific molecule among them. In this paper, a new observational avenue is suggested to detect individual PAHs, using their rotational line emission at radio frequencies. Previous PAH searches based on rotational spectroscopy have only targeted the bowl-shaped corannulene molecule, with the underlying assumption that other polar PAHs are triaxial and as a consequence their rotational emission is diluted over a very large number of lines and unusable for detection purposes. In this paper the rotational spectrum of quasi-symmetric PAHs is computed analytically, as a function of the level of triaxiality. It is shown that the asymmetry of planar, nitrogen-substituted symmetric PAHs is small enough that their rotational spectrum, when observed with a resolution of about a MHz, has ...

  16. Physical Processes of Interstellar Turbulence

    CERN Document Server

    Vazquez-Semadeni, Enrique

    2012-01-01

    I discuss the role of self-gravity and radiative heating and cooling in shaping the nature of the turbulence in the interstellar medium (ISM) of our galaxy. The heating and cooling cause it to be highly compressible, and, in some regimes of density and temperature, to become thermally unstable, tending to spontaneously segregate into warm/diffuse and cold/dense phases. On the other hand, turbulence is an inherently mixing process, tending to replenish the density and temperature ranges that would be forbidden under thermal processes alone. The turbulence in the ionized ISM appears to be transonic (i.e, with Mach numbers $\\Ms \\sim 1$), and thus to behave essentially incompressibly. However, in the neutral medium, thermal instability causes the sound speed of the gas to fluctuate by up to factors of $\\sim 30$, and thus the flow can be highly supersonic with respect to the dense/cold gas, although numerical simulations suggest that this behavior corresponds more to the ensemble of cold clumps than to the clumps'...

  17. Complex Organics from Laboratory Simulated Interstellar Ices

    Science.gov (United States)

    Dworkin, J. P.

    2003-01-01

    Many of the volatiles in interstellar dense clouds exist in ices surrounding dust grains. The low temperatures of these ices (T organics. We study the UV and proton radiation processing of interstellar ice analogs to explore links between interstellar chemistry, the organics in comets and meteorites, and the origin of life on Earth. The high D/H ratios in some interstellar species, and the knowledge that many of the organics in primitive meteorites are D-enriched, suggest that such links are plausible. Once identified, these species may serve as markers of interstellar heritage of cometary dust and meteorites. Of particular interest are our findings that UV photolysis of interstellar ice analogs produce molecules of importance in current living organisms, including quinones, amphiphiles, and amino acids. Quinones are essential in vital metabolic roles such as electron transport. Studies show that quinones should be made wherever polycyclic aromatic hydrocarbons are photolyzed in interstellar ices. In the case of anthracene-containing ices, we have observed the production of 9-anthrone and 9,10 anthraquinone, both of which have been observed in the Murchison meteorite. Amphiphiles are also made when mixed molecular ices are photolyzed. These amphiphiles self-assemble into fluorescent vesicles when placed in liquid water, as do Murchison extracts. Both have the ability to trap an ionic dye. Photolysis of plausible ices can also produce alanine, serine, and glycine as well as a number of small alcohols and amines. Flash heating of the room temperature residue generated by such experiments generates mass spectral distributions similar to those of IDPs. The detection of high D/H ratios in some interstellar molecular species, and the knowledge that many of the organics, such as hydroxy and amino acids, in primitive meteorites are D-enriched provides evidence for a connection between intact organic material in the interstellar medium and in meteorites. Thus, some of the

  18. Creation of a library tour application for mobile equipment using iBeacon technology

    OpenAIRE

    2016-01-01

    We describe the design, development, and deployment of a library tour application utilizing Bluetooth Low Energy devices know as iBeacons. The tour application will serve as library orientation for incoming students. The students visit stations in the library with mobile equipment running a special tour app. When the app detects a beacon nearby, it automatically plays a video that describes the current location. After the tour, students are assessed according to the defined learning objective...

  19. Perancangan Prototipe Receiver Beacon Black Box Locator Acoustic 37,5 kHz Pingers

    OpenAIRE

    RUSTAMAJI RUSTAMAJI; PAULINE RAHMIATI; SARAH PERMATASARI

    2016-01-01

    Abstrak Ketika suatu pesawat terbang mengalami kecelakaan terjatuh ke dalam air, maka lokasi keberadaannya dapat dideteksi oleh alat yang disebut receiver beacon black box locator acoustic (pingers receiver). Pingers receiver berfungsi untuk menerima sinyal dengan frekuensi 37,5 kHz ± 1 kHz dari pingers transmitter atau Underwater Locator Beacon (ULB) yang berada pada black box pesawat. Dalam penelitian ini dibuat perancangan pingers receiver yang tersusun dari rangkaian Band Pass Filter (BPF...

  20. Detection of jamming transmission of beacon in vehicular networks%VANETs 中 beacon 的传输攻击实时检测算法

    Institute of Scientific and Technical Information of China (English)

    陈丹; 彭利民

    2015-01-01

    车载自组织网(vehicular Ad hoc networks,VANETs)中的车辆通过周期交互 beacon 实现信息共享,从而提高交通安全,然而 VANETs 无线网络特性系统易遭受多类攻击,特别是对 beacon 的传输攻击,即干扰 beacon的传输,其严重影响 VANETs 的安全性能。为此,建立车队 platooning 模型,提出实时检测干扰 beacon 传输的攻击方案。该方案首先将节点 beacon 传输时间分为相互独立的时隙,并依据此时隙将车辆分为不同的群,使得群间的 beacon 彼此不碰撞,从而降低 beacon 被干扰的概率。最后,针对两类攻击类型进行仿真。仿真结果表明,提出的检测攻击方案具有良好的性能,初始检测时间小于150 ms,平均检测率不低于0.9。在两个干扰者的情况下,漏警率小于0.15,平均的虚警率小于0.2。%The cooperation between the vehicles in the VANET is achieved by the frequent exchange of periodic broadcast messages carrying information on vehicle position and velocity,which is referred to as beacons,which is in favor of improving the security of VANET.However,the nature of medium in wireless networks makes it easy for adversary to launch a attack, especially jamming the beacon transmission,which seriously affects the performance of VANET.Therefore,this paper con-structed the model of platooning,and proposed a real-time detection jamming-beacon-transmission scheme.In this scheme,it divided time for transmission beacon into independent time slot.In the way that beacons from different groups never collided, it reduced the probability of interference with beacon.Finally,in view of the two types of attack types were simulated.The simulation results show that the proposed detection attack scheme has good performance,the initial detecting time is less than 150 ms,the average detection rate is not less than 0.9.In the case of two jammers,FNR is less than 0.15,the average FPR is less than 0.2.

  1. Noninvasive Monitoring of Three-Dimensional Chondrogenic Constructs Using Molecular Beacon Nanosensors.

    Science.gov (United States)

    Tay, Li Min; Wiraja, Christian; Yeo, David C; Wu, Yingnan; Yang, Zheng; Chuah, Yon Jin; Lee, Eng Hin; Kang, Yuejun; Xu, Chenjie

    2017-01-01

    Chondrogenic differentiation of human mesenchymal stem cells (MSCs) in three-dimensional hydrogel holds promise as a method for repairing injured articular cartilage. Given MSC plasticity (its potential to mature into alternative lineages), nondestructive monitoring is critical for the optimization of chondrogenic differentiation conditions and the evaluation of the final product. However, conventional validation/assessments of the differentiation process (i.e., quantitative reverse transcription polymerase chain reaction [qRT-PCR] and histology) are end-point assays requiring disruption of the sample. This report introduces molecular beacon (MB)-based nanosensors to achieve noninvasive monitoring of chondrogenic differentiation. These nanosensors consist of biodegradable poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) encapsulating MBs to detect Type II Collagen (Col2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNAs that serve as lineage-specific and housekeeping biomarkers, respectively. The sustainable release of MBs from MB-NPs allows longitudinal monitoring of MSCs undergoing chondrogenic differentiation over a period of 28 days. Dual-colored MB loading ensures accurate assessment of Col2 mRNA expression level, where potential heterogeneity in nanosensor uptake and retention by MSCs are taken into account. When normalized nanosensor signal was compared against qRT-PCR result, a tight correlation was observed (R(2) = 0.9301). Finally, nanosensor usage was compatible with MSC potency with minimal influence on chondrogenic, adipogenic, and osteogenic differentiation.

  2. A molecular beacon biosensor based on the nanostructured aluminum oxide surface.

    Science.gov (United States)

    Che, Xiangchen; He, Yuan; Yin, Haocheng; Que, Long

    2015-10-15

    A new class of molecular beacon biosensors based on the nanostructured aluminum oxide or anodic aluminum oxide (AAO) surface is reported. In this type of sensor, the AAO surface is used to enhance the fluorescent signals of the fluorophore-labeled hairpin DNA. When a target DNA with a complementary sequence to that of the hairpin DNA is applied on the sensor, the fluorophores are forced to move away from the AAO surface due to the hybridization between the hairpin DNA and the target DNA, resulting in the significant decrease of the fluorescent signals. The observed signal reduction is sufficient to achieve a demonstrated detection limit of 10nM, which could be further improved by optimizing the AAO surface. The control experiments have also demonstrated that the bioassay used in the experiments has excellent specificity and selectivity, indicating the great promise of this type of sensor for diagnostic applications. Since the arrayed AAO micropatterns can be fabricated on a single chip in a cost-effective manner, the arrayed sensors could provide an ideal technical platform for studying fundamental biological process and monitoring disease biomarkers.

  3. Electrochemical molecular beacon biosensor for sequence-specific recognition of double-stranded DNA.

    Science.gov (United States)

    Miao, Xiangmin; Guo, Xiaoting; Xiao, Zhiyou; Ling, Liansheng

    2014-09-15

    Direct recognition of double-stranded DNA (dsDNA) was crucial to disease diagnosis and gene therapy, because DNA in its natural state is double stranded. Here, a novel sensor for the sequence-specific recognition of dsDNA was developed based on the structure change of ferrocene (Fc) redox probe modified molecular beacon (MB). For constructing such a sensor, gold nanoparticles (AuNPs) were initially electrochemical-deposited onto glass carbon electrode (GCE) surface to immobilize thiolated MB in their folded states with Au-S bond. Hybridization of MB with target dsDNA induced the formation of parallel triplex DNA and opened the stem-loop structure of it, which resulted in the redox probe (Fc) away from the electrode and triggered the decrease of current signals. Under optimal conditions, dsDNA detection could be realized in the range from 350 pM to 25 nM, with a detection limit of 275 pM. Moreover, the proposed method has good sequence-specificity for target dsDNA compared with single base pair mismatch and two base pairs mismatches.

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

    Directory of Open Access Journals (Sweden)

    Arturo Torres-González

    2014-04-01

    Full Text Available 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.

  5. Accelerated Adoption of Advanced Health Information Technology in Beacon Community Health Centers.

    Science.gov (United States)

    Jones, Emily; Wittie, Michael

    2015-01-01

    To complement national and state-level HITECH Act programs, 17 Beacon communities were funded to fuel community-wide use of health information technology to improve quality. Health centers in Beacon communities received supplemental funding. This article explores the association between participation in the Beacon program and the adoption of electronic health records. Using the 2010-2012 Uniform Data System, trends in health information technology adoption among health centers located within and outside of Beacon communities were explored using differences in mean t tests and multivariate logistic regression. Electronic health record adoption was widespread and rapidly growing in all health centers, especially quality improvement functionalities: structured data capture, order and results management, and clinical decision support. Adoption lagged for functionalities supporting patient engagement, performance measurement, care coordination, and public health. The use of advanced functionalities such as care coordination grew faster in Beacon health centers, and Beacon health centers had 1.7 times higher odds of adopting health records with basic safety and quality functionalities in 2010-2012. Three factors likely underlie these findings: technical assistance, community-wide activation supporting health information exchange, and the layering of financial incentives. Additional technical assistance and community-wide activation is needed to support the use of functionalities that are currently lagging. © Copyright 2015 by the American Board of Family Medicine.

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

    Science.gov (United States)

    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. Copyright © 2011 John Wiley & Sons, Ltd.

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

    Science.gov (United States)

    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.

  8. Molecular Spectroscopy in Astrophysics: Interstellar PAHs

    Science.gov (United States)

    Salama, Farid; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are now considered to be an important and ubiquitous component of the organic material in space. PAHs are found in a large variety of extraterrestrial materials such as interplanetary dust particles (IDPs) and meteoritic materials. PAHs are also good candidates to account for the infrared emission bands (UIRs) and the diffuse interstellar optical absorption bands (DIBs) detected in various regions of the interstellar medium. The recent observations made with the Infrared Space Observatory (ISO) have confirmed the ubiquitous nature of the UIR bands and their carriers. PAHs are thought to form through chemical reactions in the outflow from carbon-rich stars in a process similar to soot formation. Once injected in the interstellar medium, PAHs are further processed by the interstellar radiation field, interstellar shocks and energetic particles. A long-term laboratory effort has been undertaken to measure the physical and chemical characteristics of these carbon molecules and their ions under experimental conditions that mimic the interstellar conditions. These measurements require collision-free conditions where the molecules and ions are cold and chemically isolated. The spectroscopy of PAHs under controlled conditions represents an essential diagnostic tool to study the evolution of extraterrestrial PAHs. The laboratory results will be discussed as well as the implications for astronomy and for molecular spectroscopy. A review of the data generated through laboratory simulations of space environments and the role these data have played in our current understanding of the properties of interstellar PAHs will be presented. We will also present the new generation of laboratory experiments that are currently being developed in order to provide a closer simulation of space environments and a better support to space missions.

  9. A solid-state electrochemiluminescence biosensing switch for detection of DNA hybridization based on ferrocene-labeled molecular beacon

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xiaoying [School of Public Health, Southeast University, Nanjing 210009 (China); He Pingang, E-mail: pghe@chem.ecnu.edu.c [Department of Chemistry, East China Normal University, Shanghai 200062 (China); Fang Yuzhi, E-mail: yzfang@chem.ecnu.edu.c [Department of Chemistry, East China Normal University, Shanghai 200062 (China)

    2010-08-15

    A solid-state electrochemiluminescence (ECL) biosensing switch incorporating quenching of ECL of ruthenium(II) tris-(bipyridine) (Ru(bpy){sub 3}{sup 2+}) by ferrocene (Fc) has been successfully developed for DNA hybridization detection. The important issue for this biosensing system is based on the ferrocene-labeled molecular beacon (Fc-MB), i.e. using the special Fc-MB to react with the target DNA and then change its structure, resulting in an ECL intensity change. Under the optimal conditions, the difference of ECL intensity before and after the hybridization reaction ({Delta}I{sub ECL}) was linearly related to the concentration of the complementary sequence in the range of 10 fM-10 pM and the detection limit was down to 1.0 fM.

  10. Proposal of a new generation of Laser Beacon for time calibration in the KM3NeT neutrino telescope

    Energy Technology Data Exchange (ETDEWEB)

    Real, Diego [IFIC, Instituto de Física Corpuscular, CSIC-Universidad de Valencia, C/Catedrático José Beltrán, 2. 46980 Paterna (Spain); Collaboration: KM3NeT Collaboration

    2014-11-18

    The KM3NeT collaboration aims at the construction of a multi-km3 high-energy neutrino telescope in the Mediterranean Sea consisting of a matrix of pressure resistant glass spheres holding each a set (31) of small area photomultipliers. The main motivation of the telescope is to observe cosmic neutrinos through the Cherenkov light induced in sea water by charged particles produced in neutrino interactions with the surrounding medium. A relative time calibration between photomultipliers of the order of 1 ns is required to achieve an optimal performance. To this end, several time calibration subsystems have been developed. In this article, the proposal of a last generation Laser Beacon, to be used in KM3NeT and developed to measure and monitor the relative time offsets between photomultipliers, is presented.

  11. Organic chemistry and biology of the interstellar medium

    Science.gov (United States)

    Sagan, C.

    1973-01-01

    Interstellar organic chemistry is discussed as the field of study emerging from the discovery of microwave lines of formaldehyde and of hydrogen cyanide in the interstellar medium. The reliability of molecular identifications and comparisons of interstellar and cometary compounds are considered, along with the degradational origin of simple organics. It is pointed out that the contribution of interstellar organic chemistry to problems in biology is not substantive but analogical. The interstellar medium reveals the operation of chemical processes which, on earth and perhaps on vast numbers of planets throughout the universe, led to the origin of life, but the actual molecules of the interstellar medium are unlikely to play any significant biological role.

  12. Novel Molecular Beacon Probe-Based Real-Time RT-PCR Assay for Diagnosis of Crimean-Congo Hemorrhagic Fever Encountered in India

    Directory of Open Access Journals (Sweden)

    Aman Kamboj

    2014-01-01

    Full Text Available Crimean-Congo hemorrhagic fever (CCHF is an emerging zoonotic disease in India and requires immediate detection of infection both for preventing further transmission and for controlling the infection. The present study describes development, optimization, and evaluation of a novel molecular beacon-based real-time RT-PCR assay for rapid, sensitive, and specific diagnosis of Crimean-Congo hemorrhagic fever virus (CCHFV. The developed assay was found to be a better alternative to the reported TaqMan assay for routine diagnosis of CCHF.

  13. A Measurement Study of BLE iBeacon and Geometric Adjustment Scheme for Indoor Location-Based Mobile Applications

    OpenAIRE

    2016-01-01

    Bluetooth Low Energy (BLE) and the iBeacons have recently gained large interest for enabling various proximity-based application services. Given the ubiquitously deployed nature of Bluetooth devices including mobile smartphones, using BLE and iBeacon technologies seemed to be a promising future to come. This work started off with the belief that this was true: iBeacons could provide us with the accuracy in proximity and distance estimation to enable and simplify the development of many previo...

  14. Interstellar Dust in the Solar System

    CERN Document Server

    Krueger, Harald; Altobelli, Nicolas; Gruen, Eberhard

    2007-01-01

    The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse almost perpendicular to the ecliptic plane (inclination 79 deg, perihelion distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in 1992. The in-situ dust detector on board continuously measured interstellar dust grains with masses up to 10^-13 kg, penetrating deep into the solar system. The flow direction is close to the mean apex of the Sun's motion through the solar system and the grains act as tracers of the physical conditions in the local interstellar cloud (LIC). While Ulysses monitored the interstellar dust stream at high ecliptic latitudes between 3 and 5 AU, interstellar impactors were also measured with the in-situ dust detectors on board Cassini, Galileo and Helios, covering a heliocentric distance range between 0.3 and 3 AU in the ecliptic plane. The interstellar dust stream in the inner solar system is altered by the solar radiation pressure force, gravitational focussing and interaction of charged gr...

  15. Prospective of Photon Propulsion for Interstellar Flight

    Science.gov (United States)

    Bae, Young K.

    Mastering photon propulsion is proposed to be the key to overcoming the limit of the current propulsion technology based on conventional rocketry and potentially opening a new space era. A perspective on photon propulsion is presented here to elucidate that interstellar manned roundtrip flight could be achievable in a century within a frame of exiting scientific principles, once the required existing technologies are further developed. It is shown that the developmental pathway towards the interstellar flight demands not only technological breakthroughs, but consistent long-term world-scale economic interest and investment. Such interest and investment will result from positive financial returns from routine interstellar commutes that can transport highly valuable commodities in a profitable manner. The Photonic Railway, a permanent energy-efficient transportation structure based on the Beamed-Laser Propulsion (BLP) by Forward and the Photonic Laser Thruster (PLT) by the author, is proposed to enable such routine interstellar commutes via Spacetrains. A four-phased evolutionary developmental pathway towards the Interstellar Photonic Railway is proposed. Each phase poses evolutionary, yet daunting, technological and financial challenges that need to be overcome within each time frame of 20 _ 30 years, and is projected to generate multitudes of applications that would lead to sustainable reinvestment into its development. If successfully developed, the Photonic Railway would bring about a quantum leap in the human economic and social interests in space from explorations to terraforming, mining, colonization, and permanent habitation in exoplanets.

  16. O vi in the local interstellar medium

    CERN Document Server

    Barstow, M A; Welsh, B Y; Lallement, R; Preval, J K Barstow A E Forbes And S

    2010-01-01

    We report the results of a search for O VI absorption in the spectra of 80 hot DA white dwarfs observed by the FUSE satellite. We have carried out a detailed analysis of the radial velocities of interstellar and (where present) stellar absorption lines for the entire sample of stars. In approximately 35% of cases (where photospheric material is detected), the velocity differences between the interstellar and photospheric components were beneath the resolution of the FUSE spectrographs. Therefore, in 65% of these stars the interstellar and photospheric contributions could be separated and the nature of the O VI component unambiguously determined. Furthermore, in other examples, where the spectra were of a high signal-to-noise, no photospheric material was found and any O VI detected was assumed to be interstellar. Building on the earlier work of Oegerle et al. (2005) and Savage & Lehner (2006), we have increased the number of detections of interstellar O VI and, for the first time, compared their locations...

  17. Communicating Concepts about Altruism in Interstellar Messages

    Science.gov (United States)

    Vakoch, Douglas A.

    2002-01-01

    This project identifies key principles of altruism that can be translated into interstellar messages for communication with extraterrestrial intelligence. The message contents will focus specifically on the evolution of altruism, drawing on recent insights in evolutionary biology, with particular emphasis on sociobiological accounts of kin selection and reciprocal altruism. This focus on altruism for message contents has several advantages. First, the subject can be translated into interstellar messages both via an existing formal interstellar language and via pictorial messages. For example, aspects of reciprocal altruism can be described through mathematical modeling, such as game theoretic approaches, which in turn can be described readily in the interstellar language Lincos. Second, concentrating on altruism as a message content may facilitate communications with extraterrestrial intelligence. Some scientists have argued that humans may be expected to communicate something about their moral status and development in an exchange with extraterrestrials. One of the most salient ways that terrestrial and extraterrestrial civilizations might be expected to evaluate one another is in terms of ethical motivations. Indeed, current search strategies assume some measure of altruism on the part of transmitting civilizations; with no guarantee of a response, the other civilization would be providing information to us with no direct payoff. Thus, concepts about altruism provide an appropriate content for interstellar messages, because the concepts themselves might be understood by extraterrestrial civilizations.

  18. Interstellar processes; Proceedings of the Symposium, Grand Teton National Park, WY, July 1-7, 1986

    Science.gov (United States)

    Hollenbach, David J. (Editor); Thronson, Harley A., Jr. (Editor)

    1987-01-01

    The conference presents papers on the Milky Way as a galaxy; observations of components of the interstellar medium; interstellar magnetic properties; interstellar processes on a galactic scale; dynamical processes in interstellar clouds; interstellar dust grains; interstellar chemical processes; and heating, cooling, and radiative processes. Attention is given to H2 in the Galaxy, hot interstellar gas in the Galactic disk and halo, interstellar magnetic fields, cloud formation and destruction, theoretical approaches to interstellar turbulence, and infrared absorption and emission characteristics of interstellar PAHs. Other topics include gas phase chemical processes in molecular clouds, the chemical evolution of galaxies, and the atomic and molecular physics of interstellar heating and cooling.

  19. Investigating nearby exoplanets via interstellar radar

    Science.gov (United States)

    Scheffer, Louis K.

    2014-01-01

    Interstellar radar is a potential intermediate step between passive observation of exoplanets and interstellar exploratory missions. Compared with passive observation, it has the traditional advantages of radar astronomy. It can measure surface characteristics, determine spin rates and axes, provide extremely accurate ranges, construct maps of planets, distinguish liquid from solid surfaces, find rings and moons, and penetrate clouds. It can do this even for planets close to the parent star. Compared with interstellar travel or probes, it also offers significant advantages. The technology required to build such a radar already exists, radar can return results within a human lifetime, and a single facility can investigate thousands of planetary systems. The cost, although too high for current implementation, is within the reach of Earth's economy.

  20. Long-Term Perspectives on Interstellar Flight

    Science.gov (United States)

    Michaud, M. A. G.

    Realizing interstellar travel by machines or living beings will require not only scientific and technological progress, but also a shared secular belief among a determined minority that this enterprise is important for the human future. Their efforts may have to extend beyond individual human lifetimes. Historical perspectives, on both the past and the future, are proposed. Interstellar probes could be a more thorough way of searching for alien forms of life and intelligence in nearby systems, particularly if there were intelligent beings there who did not employ technologies our astronomical observing devices can detect from here. Perspectives on the ethical, policy, and design issues of such close encounters with alien life and intelligence are presented. Ways of accelerating the coming of interstellar probes are suggested.

  1. Model atmospheres - Tool for identifying interstellar features

    Science.gov (United States)

    Frisch, P. C.; Slojkowski, S. E.; Rodriguez-Bell, T.; York, D.

    1993-01-01

    Model atmosphere parameters are derived for 14 early A stars with rotation velocities, from optical spectra, in excess of 80 km/s. The models are compared with IUE observations of the stars in regions where interstellar lines are expected. In general, with the assumption of solar abundances, excellent fits are obtained in regions longward of 2580 A, and accurate interstellar equivalent widths can be derived using models to establish the continuum. The fits are poorer at shorter wavelengths, particularly at 2026-2062 A, where the stellar model parameters seem inadequate. Features indicating mass flows are evident in stars with known infrared excesses. In gamma TrA, variability in the Mg II lines is seen over the 5-year interval of these data, and also over timescales as short as 26 days. The present technique should be useful in systematic studies of episodic mass flows in A stars and for stellar abundance studies, as well as interstellar features.

  2. Investigating Nearby Exoplanets via Interstellar Radar

    CERN Document Server

    Scheffer, Louis K

    2013-01-01

    Interstellar radar is a potential intermediate step between passive observation of exoplanets and interstellar exploratory missions. Compared to passive observation, it has the traditional advantages of radar astronomy. It can measure surface characteristics, determine spin rates and axes, provide extremely accurate ranges, construct maps of planets, distinguish liquid from solid surfaces, find rings and moons, and penetrate clouds. It can do this even for planets close to the parent star. Compared to interstellar travel or probes, it also offers significant advantages. The technology required to build such a radar already exists, radar can return results within a human lifetime, and a single facility can investigate thousands of planetary systems. The cost, although high, is within the reach of Earth's economy, so it is cheaper as well.

  3. Observational astrochemistry: The quest for interstellar molecules

    Directory of Open Access Journals (Sweden)

    Guélin M.

    2012-01-01

    Full Text Available Over 160 molecular species, not counting isotopologues, have been identified in circumstellar envelopes and interstellar clouds. These species have revealed a wealth of familiar, as much as exotic molecules and in complex organic (and silicon compounds, that was fully unexpected in view of the harshness of surrounding conditions: vanishingly low densities, extreme temperatures and intense embedding UV radiation. They illustrate the diversity of astrochemistry and show robust prebiotic molecules may be. In this lecture, we review the quest for interstellar molecules and show how tributary it is from theoretical ideas and technology developments. A. A. Penzias, who discovered interstellar CO and the 2.7 K Cosmic Background radiation, used to joke that astronomical research is easy: the great questions have largely been formulated; one only has to wait until technological progress makes it possible to answer.

  4. Interstellar water chemistry: from laboratory to observations

    CERN Document Server

    van Dishoeck, Ewine F; Neufeld, David A

    2013-01-01

    Water is observed throughout the universe, from diffuse interstellar clouds to protoplanetary disks around young stars, and from comets in our own solar system and exoplanetary atmospheres to galaxies at high redshifts. This review summarizes the spectroscopy and excitation of water in interstellar space as well as the basic chemical processes that form and destroy water under interstellar conditions. Three major routes to water formation are identified: low temperature ion-molecule chemistry, high-temperature neutral-neutral chemistry and gas-ice chemistry. The rate coefficients of several important processes entering the networks are discussed in detail; several of them have been determined only in the last decade through laboratory experiments and theoretical calculations. Astronomical examples of each of the different chemical routes are presented using data from powerful new telescopes, in particular the Herschel Space Observatory. Basic chemical physics studies remain critically important to analyze ast...

  5. Interstellar Travel. (Latest citations from the Aerospace Database)

    Science.gov (United States)

    1996-01-01

    The bibliography contains citations concerning travel between the stars. Topics include cost considerations, hyperspace navigation, exploration, and propulsion systems for vehicles to be used in interstellar travel. Human factor issues and social aspects of interstellar travel are also discussed.

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

    Science.gov (United States)

    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.

  7. Problems of Interplanetary and Interstellar Trade

    Science.gov (United States)

    Hickman, John

    2008-01-01

    If and when interplanetary and interstellar trade develops, it will be novel in two respects. First, the distances and time spans involved will reduce all or nearly all trade to the exchange of intangible goods. That threatens the possibility of conducting business in a genuinely common currency and of enforcing debt agreements, especially those involving sovereign debt. Second, interstellar trade suggests trade between humans and aliens. Cultural distance is a probable obstacle to initiating and sustaining such trade. Such exchange also threatens the release of new and potentially toxic memes.

  8. Water in the interstellar media of galaxies

    CERN Document Server

    van der Tak, Floris

    2015-01-01

    This paper reviews recent observations of water in Galactic interstellar clouds and nearby galactic nuclei. Two results are highlighted: (1) Multi-line H$_2$O mapping of the Orion Bar shows that the water chemistry in PDRs is driven by photodissociation and -desorption, unlike in star-forming regions. (2) High-resolution spectra of H$_2$O and its ions toward 5 starburst / AGN systems reveal low ionization rates, unlike as found from higher-excitation lines. We conclude that the chemistry of water strongly depends on radiation environment, and that the ionization rates of interstellar clouds decrease by at least 10 between galactic nuclei and disks.

  9. Interstellar gas in the Gum Nebula

    Science.gov (United States)

    Wallerstein, G.; Jenkins, E. B.; Silk, J.

    1980-01-01

    A survey of the interstellar gas near the Gum Nebula by optical observation of 67 stars at Ca II, 42 stars at Na I, and 14 stars in the UV with the Copernicus satellite provided radial velocities and column densities for all resolved absorption components. Velocity dispersions for gas in the Gum Nebula are not significantly larger than in the general interstellar medium; the ionization structure is predominantly that of an H II region with moderately high ionization. Denser, more highly ionized clouds are concentrated toward the Gum Nebula; these clouds do not show the anomalously high ionization observed in the Vela remnant clouds.

  10. Status of Solar Sail Propulsion: Moving Toward an Interstellar Probe

    Science.gov (United States)

    Johnson, Les; Young, Roy M.; Montgomery, Edward E., IV

    2006-01-01

    NASA's In-Space Propulsion Technology Program has developed the first-generation of solar sail propulsion systems sufficient to accomplish inner solar system science and exploration missions. These first-generation solar sails, when operational, will range in size from 40 meters to well over 100 meters in diameter and have an areal density of less than 13 grams-per-square meter. A rigorous, multiyear technology development effort culminated last year in the testing of two different 20-meter solar sail systems under thermal vacuum conditions. This effort provided a number of significant insights into the optimal design and expected performance of solar sails as well as an understanding of the methods and costs of building and using them. In a separate effort, solar sail orbital analysis tools for mission design were developed and tested. Laboratory simulations of the effects of long-term space radiation exposure were also conducted on two candidate solar sail materials. Detailed radiation and charging environments were defined for mission trajectories outside the protection of the earth's magnetosphere, in the solar wind environment. These were used in other analytical tools to prove the adequacy of sail design features for accommodating the harsh space environment. Preceding, and in conjunction with these technology efforts, NASA sponsored several mission application studies for solar sails, including one that would use an evolved sail capability to support humanity's first mission into nearby interstellar space. The proposed mission is called the Interstellar Probe. The Interstellar Probe might be accomplished in several ways. A 200-meter sail, with an areal density approaching 1 gram-per-square meter, could accelerate a robotic probe to the very edge of the solar system in just under 20 years from launch. A sail using the technology just demonstrated could make the same mission, but take significantly longer. Conventional chemical propulsion systems would require

  11. Observing the Interstellar Neutral He Gas Flow with a Variable IBEX Pointing Strategy

    Science.gov (United States)

    Leonard, T.; Moebius, E.; Bzowski, M.; Fuselier, S. A.; Heirtzler, D.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; McComas, D. J.; Schwadron, N.; Wurz, P.

    2015-12-01

    The Interstellar Neutral (ISN) gas flow can be observed at Earth's orbit due to the motion of the solar system relative to the surrounding interstellar gas. Since He is minimally influenced by ionization and charge exchange, the ISN He flow provides a sample of the pristine interstellar environment. The Interstellar Boundary Explorer (IBEX) has observed the ISN gas flow over the past 7 years from a highly elliptical orbit around the Earth. IBEX is a Sun-pointing spinning spacecraft with energetic neutral atom (ENA) detectors observing perpendicular to the spacecraft spin axis. Due to the Earth's orbital motion around the Sun, it is necessary for IBEX to perform spin axis pointing maneuvers every few days to maintain a sunward pointed spin axis. The IBEX operations team has successfully pointed the spin axis in a variety of latitude orientations during the mission, including in the ecliptic during the 2012 and 2013 seasons, about 5 degrees below the ecliptic during the 2014 season, and recently about 5 degrees above the ecliptic during the 2015 season, as well as optimizing observations with the spin axis pointed along the Earth-Sun line. These observations include a growing number of measurements near the perihelion of the interstellar atom trajectories, which allow for an improved determination of the ISN He bulk flow longitude at Earth orbit. Combining these bulk flow measurements with an analytical model (Lee et al. 2012 ApJS, 198, 10) based upon orbital mechanics improves the knowledge of the narrow ISN parameter tube, obtained with IBEX, which couples the interstellar inflow longitude, latitude, speed, and temperature.

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

    Directory of Open Access Journals (Sweden)

    Ambra Giannetti

    2015-04-01

    Full Text Available 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.

  13. STEREO Space Weather and the Space Weather Beacon

    Science.gov (United States)

    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.

  14. First tests of wavefront sensing with a constellation of laser guide beacons

    CERN Document Server

    Lloyd-Hart, M; Milton, N M; Stalcup, T; Snyder, M; Putnam, N; Angel, J R P

    2005-01-01

    Adaptive optics to correct current telescopes over wide fields, or future very large telescopes over even narrow fields, will require real-time wavefront measurements made with a constellation of laser beacons. Here we report the first such measurements, made at the 6.5 m MMT with five Rayleigh beacons in a 2 arcmin pentagon. Each beacon is made with a pulsed beam at 532 nm, of 4 W at the exit pupil of the projector. The return is range-gated from 20-29 km and recorded at 53 Hz by a 36-element Shack-Hartmann sensor. Wavefronts derived from the beacons are compared with simultaneous wavefronts obtained for individual natural stars within or near the constellation. Observations were made in seeing averaging 1.0 arcsec with 2/3 of the aberration measured to be from a ground layer of mean height 380 m. Under these conditions, subtraction of the simple instantaneous average of the five beacon wavefronts from the stellar wavefronts yielded a 40% rms reduction in the measured modes of the distortion over a 2 arcmin ...

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

    Science.gov (United States)

    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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. DNA Duplex-Based Photodynamic Molecular Beacon for Targeted Killing of Retinoblastoma Cell.

    Science.gov (United States)

    Wei, Yanchun; Lu, Cuixia; Chen, Qun; Xing, Da

    2016-11-01

    Retinoblastoma (RB) is the most common primary intraocular malignancy of infancy. An alternative RB treatment protocol is proposed and tested. It is based on a photodynamic therapy (PDT) with a designed molecular beacon that specifically targets the murine double minute x (MDMX) high-expressed RB cells. A MDMX mRNA triggered photodynamic molecular beacon is designed by binding a photosensitizer molecule (pyropheophorbide-a, or PPa) and a black hole quencher-3 (BHQ3) through a complementary oligonucleotide sequence. Cells with and without MDMX high-expression are incubated with the beacon and then irradiated with a laser. The fluorescence and reactive oxygen species are detected in solution to verify the specific activation of PPa by the perfectly matched DNA targets. The cell viabilities are evaluated with CCK-8 and flow cytometry assay. The fluorescence and photo-cytoxicity of PPa is recovered and significantly higher in the MDMX high-expressed Y79 and WERI-Rb1 cells, compared to that with the MDMX low-expressed cells. The synthesized beacon exhibits high PDT efficiency toward MDMX high-expressed RB cells. The data suggest that the designed beacon may provide a potential alternative for RB therapy and secures the ground for future investigation.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Adaptive Beaconing in Mobility Aware Clustering Based MAC Protocol for Safety Message Dissemination in VANET

    Directory of Open Access Journals (Sweden)

    Nishu Gupta

    2017-01-01

    Full Text Available Majority of research contributions in wireless access in vehicular environment (WAVE/IEEE 802.11p standard focus on life critical safety-related applications. These applications require regular status update of vehicle’s position referred to as beaconing. Periodic beaconing in vehicle to vehicle communication leads to severe network congestion in the communication channel. The condition worsens under high vehicular density where it impacts reliability and upper bound latency of safety messages. In this paper, WAVE compliant enhancement to the existing IEEE 802.11p protocol is presented which targets prioritized delivery of safety messages while simultaneously provisioning the dissemination of nonsafety messages. Proposed scheme relies on dynamic generation of beacons to mitigate channel congestion and inefficient bandwidth utilization by reducing transmission frequency of beacons. Through the use of clustering mechanism, different beaconing frequencies and different data transmission rates are assigned to prioritize vehicular mobility. Through extensive simulation results, the performance of the proposed approach is evaluated in terms of a wide range of quality of service (QoS parameters for two different transmission ranges. Results show that the proposed protocol provides significant enhancement and stability of the clustered topology in vehicular ad hoc network over existing standard and other protocols with similar applications.

  2. The Voyager Journey to Interstellar Space

    Science.gov (United States)

    Stone, E. C.

    Launched in 1977 to explore Jupiter, Saturn, Uranus, and Neptune, the two Voyager spacecraft continued their journeys beyond the planets as they searched for the heliopause, the boundary between the solar wind and the local interstellar medium. After traveling more than 23 billion kilometers, Voyager 1 left the heliosphere on August 25, 2012, and began returning the first in-situ observations of local interstellar space. Voyager 1 found a wall of interstellar plasma beyond the heliopause with a density forty times greater than inside and an interstellar magnetic field that is compressed and wrapped around the outside. Voyager 1 also observed the energy spectrum of low energy galactic cosmic ray protons that are excluded from the heliosphere by solar modulation, finding a peak intensity at ˜30 MeV. that is ten times the maximum intensity at 1 AU that occurs at ˜300 MeV. An overview of the journey and the new aspects of the interaction of the sun and the nearby region of the Milky Way will be discussed.

  3. Bubbles and holes in the interstellar medium

    NARCIS (Netherlands)

    vanderHulst, JM; Skillman, ED

    1996-01-01

    Studies of the HI in nearby galaxies now clearly begin to show the effects of star formation on the interstellar medium. Holes, filaments, expanding motions and other anomalous velocity signatures are clearly apparent in sensitive observations of the HI in nearby galaxies. A global relation with the

  4. The composition of circumstellar and interstellar dust

    NARCIS (Netherlands)

    Tielens, AGGM; Woodward, CE; Biscay, MD; Shull, JM

    2001-01-01

    A large number of solid dust components have been identified through analysis of stardust recovered from meteorites, and analysis of IR observations of circumstellar shells and the interstellar medium. These include graphite, hydrogenated amorphous carbon, diamond, PAHs, silicon-, iron-, and titanin

  5. Physics and chemistry of interstellar ice

    NARCIS (Netherlands)

    Guss (née Isokoski), Karoliina Marja-Riita

    2013-01-01

    The importance of ice in the interstellar medium is indisputable. Gas phase reactions relying on three-body collisions are exceedingly rare in the sparse medium between the stars. On solid surfaces, atoms and molecules can reside and rove the surface until a reaction takes place. Upon reaction, the

  6. Infrared spectroscopy of interstellar apolar ice analogs

    NARCIS (Netherlands)

    Ehrenfreund, P; Boogert, ACA; Gerakines, PA; Tielens, AGGM; van Dishoeck, EF

    1997-01-01

    Apolar ices have been observed in several regions in dense clouds and are likely dominated by molecules such as CO, CO(2) and the infrared inactive molecules O(2) and N(2). Interstellar solid CO has been well characterized by ground-based high resolution measurements. Recent ISO results showed the u

  7. Abundances and Depletions of Interstellar Oxygen

    Science.gov (United States)

    Jensen, A. G.; Rachford, B. L.; Snow, T. P.

    2003-12-01

    We extend previous work on interstellar oxygen abundances with the addition of data from the Far Ultraviolet Spectroscopic Explorer (FUSE). We report on the abundance of interstellar neutral oxygen (OI) for several sightlines, using data from FUSE, the International Spectroscopic Explorer (IUE), and the Hubble Space Telescope (HST). OI column densities are derived by measuring the equivalent widths of several ultraviolet absorption lines, and subsequently fitting those to a curve of growth. The column densities of our best-constrained sightlines show a ratio of O/H that agrees with the current best solar value if dust is considered. We do not see evidence of enhanced depletion of gas-phase oxygen that is systematically variable with respect to the physical parameters of different environments (e.g., reddening or molecular fraction). The column densities of our less well-constrained sightlines show some scatter in O/H, but many agree with the solar value to within errors. We discuss these results in the context of deriving the best methods for determining interstellar abundances, the unresolved question of the best value for O/H in the interstellar medium (ISM), the O/H ratio observed in Galactic stars, and the depletion of gas-phase oxygen onto dust grains. Financial support for this research has been provided by the National Science Foundation GK-12 Program and NASA contract NAS 5-32985.

  8. The photodissociation and chemistry of interstellar CO

    NARCIS (Netherlands)

    Dishoeck, van E.F.; Black, J.H.

    1988-01-01

    Recent work on the vacuum UV absorption spectrum of CO to the description of the photodissociation of interstellar CO and its principal isotopic varieties is discussed. The effects of line broadening, self-shielding, shielding by H and H2, and isotope-selective shielding are examined as functions of

  9. Far-infrared spectroscopy of interstellar dust

    NARCIS (Netherlands)

    Tielens, AGGM; Wilson, A

    2005-01-01

    The composition of interstellar dust is best studied using mid-infrared spectroscopy. Nevertheless, the far-infrared can make some unique contributions to this field. This includes studies on the Mg/Fe ratio and the temperature of crystalline silicates, the presence of carbonates, and the precense o

  10. A Rigorous Attempt to Verify Interstellar Glycine

    Science.gov (United States)

    Snyder, L. E.; Lovas, F. J.; Hollis, J. M.; Friedel, D. N.; Jewell, P. R.; Remijan, A.; Ilyushin, V. V.; Alekseev, E. A.; Dyubko, S. F.

    2004-01-01

    In 2003, Kuan, Charnley, and co-workers reported the detection of interstellar glycine (NH2CH2COOH) based on observations of 27 lines in 19 different spectral bands in one or more of the sources Sgr BP(N-LMH), Orion KL, and W51 e1/e2. They supported their detection report with rotational temperature diagrams for all three sources. In this paper, we present essential criteria which can be used in a straightforward analysis technique to confirm the identity of an interstellar asymmetric rotor such as glycine. We use new laboratory measurements of glycine as a basis for applying this analysis technique, both to our previously unpublished 12 m telescope data and to the previously published SEST data of Nummelin and colleagues. We conclude that key lines necessary for an interstellar glycine identification have not yet been found. We identify several common molecular candidates that should be examined further as more likely carriers of the lines reported as glycine. Finally, we illustrate that rotational temperature diagrams used without the support of correct spectroscopic assignments are not a reliable tool for the identification of interstellar molecules. Subject headings: ISM: abundances - ISM: clouds - ISM: individual (Sagittarius B2[N-

  11. The composition of circumstellar and interstellar dust

    NARCIS (Netherlands)

    Tielens, AGGM; Woodward, CE; Biscay, MD; Shull, JM

    2001-01-01

    A large number of solid dust components have been identified through analysis of stardust recovered from meteorites, and analysis of IR observations of circumstellar shells and the interstellar medium. These include graphite, hydrogenated amorphous carbon, diamond, PAHs, silicon-, iron-, and titanin

  12. A Measurement Study of BLE iBeacon and Geometric Adjustment Scheme for Indoor Location-Based Mobile Applications

    Directory of Open Access Journals (Sweden)

    Jeongyeup Paek

    2016-01-01

    Full Text Available Bluetooth Low Energy (BLE and the iBeacons have recently gained large interest for enabling various proximity-based application services. Given the ubiquitously deployed nature of Bluetooth devices including mobile smartphones, using BLE and iBeacon technologies seemed to be a promising future to come. This work started off with the belief that this was true: iBeacons could provide us with the accuracy in proximity and distance estimation to enable and simplify the development of many previously difficult applications. However, our empirical studies with three different iBeacon devices from various vendors and two types of smartphone platforms prove that this is not the case. Signal strength readings vary significantly over different iBeacon vendors, mobile platforms, environmental or deployment factors, and usage scenarios. This variability in signal strength naturally complicates the process of extracting an accurate location/proximity estimation in real environments. Our lessons on the limitations of iBeacon technique lead us to design a simple class attendance checking application by performing a simple form of geometric adjustments to compensate for the natural variations in beacon signal strength readings. We believe that the negative observations made in this work can provide future researchers with a reference on how well of a performance to expect from iBeacon devices as they enter their system design phases.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  15. 75 FR 20364 - Public Buildings Service; Key Largo Beacon Annex Site; Key Largo, FL; Transfer of Property

    Science.gov (United States)

    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...

  16. TRIANGULATION OF THE INTERSTELLAR MAGNETIC FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Schwadron, N. A.; Moebius, E. [University of New Hampshire, Durham, NH 03824 (United States); Richardson, J. D. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Burlaga, L. F. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); McComas, D. J. [Southwest Research Institute, San Antonio, TX 78228 (United States)

    2015-11-01

    Determining the direction of the local interstellar magnetic field (LISMF) is important for understanding the heliosphere’s global structure, the properties of the interstellar medium, and the propagation of cosmic rays in the local galactic medium. Measurements of interstellar neutral atoms by Ulysses for He and by SOHO/SWAN for H provided some of the first observational insights into the LISMF direction. Because secondary neutral H is partially deflected by the interstellar flow in the outer heliosheath and this deflection is influenced by the LISMF, the relative deflection of H versus He provides a plane—the so-called B–V plane in which the LISMF direction should lie. Interstellar Boundary Explorer (IBEX) subsequently discovered a ribbon, the center of which is conjectured to be the LISMF direction. The most recent He velocity measurements from IBEX and those from Ulysses yield a B–V plane with uncertainty limits that contain the centers of the IBEX ribbon at 0.7–2.7 keV. The possibility that Voyager 1 has moved into the outer heliosheath now suggests that Voyager 1's direct observations provide another independent determination of the LISMF. We show that LISMF direction measured by Voyager 1 is >40° off from the IBEX ribbon center and the B–V plane. Taking into account the temporal gradient of the field direction measured by Voyager 1, we extrapolate to a field direction that passes directly through the IBEX ribbon center (0.7–2.7 keV) and the B–V plane, allowing us to triangulate the LISMF direction and estimate the gradient scale size of the magnetic field.

  17. Kontextbaserad information genom iBeacon : En implementation i iOS och Android

    OpenAIRE

    2014-01-01

    I dagsläget växer behovet av rätt information vid rätt plats, kontextbaserad information. Med hjälp av iBeacon kan man till en stor utsträckning förse det här behovet med en lösning. I uppsatsen undersöks användningsområden för iBeacon och idéer för hur man kan utveckla lösningar med hjälp av iBeacon. Ett koncept kommer att implementeras för att distribuera kontextbaserad information på mässor. Konceptet utvecklades till iOS och Android. Applikationerna tar hjälp av en webbtjänst för att unde...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Structure and Stability of Interstellar Molecule C3S

    Institute of Scientific and Technical Information of China (English)

    YU,Hai-Tao(于海涛); FU,Hong-Gang(傅宏刚); CHI,Yu-Juan(池玉娟); HUANG,Xu-Ri(黄旭日); LI,Ze-Sheng(李泽生); SUN,Jia-Zhong(孙家钟)

    2002-01-01

    The singlet and triplet potential energy surfaces of interstellar molecule C3S are predicted at the UB3LYP/6-311 (d) and UCCSD(T)/6-311 + G(2df) (single-point) levels. The linear singlet isomer CCCS with 1 ∑ + electronic state is found to be thermodynamically and kinetically the most stable species on the singlet surface followed by other four singiet isomers, which are unstable on the basis of calculated results. On the triplet sur face, the lowest-lying species, which lies 248.79 kJ/mol above linear singlet species CCCS, is chain CCCS connectivity with 3A' electronic state. Other four triplet isomers can be considered as unstable species by means of transition state and potential energy surface scan technologies. The structures, vibrational frequencies, dipole moments and rotational constants of all optimized species are also calculated.

  2. Beacon system based on light-emitting diode sources for runways lighting

    Science.gov (United States)

    Montes, Mario González; Vázquez, Daniel; Fernandez-Balbuena, Antonio A.; Bernabeu, Eusebio

    2014-06-01

    New aeronautical ground lighting techniques are becoming increasingly important to ensure the safety and reduce the maintenance costs of the plane's tracks. Until recently, tracks had embedded lighting systems whose sources were based on incandescent lamps. But incandescent lamps have several disadvantages: high energy consumption and frequent breakdowns that result in high maintenance costs (lamp average life-time is ˜1500 operating hours) and the lamp's technology has a lack of new lighting functions, such as signal handling and modification. To solve these problems, the industry has developed systems based on light-emitting diode (LED) technology with improved features: (1) LED lighting consumes one tenth the power, (2) it improves preventive maintenance (an LED's lifetime range is between 25,000 and 100,000 hours), and (3) LED lighting technology can be controlled remotely according to the needs of the track configuration. LEDs have been in use for more than three decades, but only recently, around 2002, have they begun to be used as visual aids, representing the greatest potential change for airport lighting since their inception in the 1920s. Currently, embedded LED systems are not being broadly used due to the specific constraints of the rules and regulations of airports (beacon dimensions, power system technology, etc.). The fundamental requirements applied to embedded lighting systems are to be hosted on a volume where the dimensions are usually critical and also to integrate all the essential components for operation. An embedded architecture that meets the lighting regulations for airport runways is presented. The present work is divided into three main tasks: development of an optical system to optimize lighting according to International Civil Aviation Organization, manufacturing prototype, and model validation.

  3. Electro-optic testbed utilizing a dynamic range gated Rayleigh beacon for atmospheric turbulence profiling

    Science.gov (United States)

    Zuraski, Steven M.; Fiorino, Steven T.; Beecher, Elizabeth A.; Figlewski, Nathan M.; Schmidt, Jason D.; McCrae, Jack E.

    2016-10-01

    The Photometry Analysis and Optical Tracking and Evaluation System (PANOPTES) Quad Axis Telescope is a unique four axis mount Ritchey-Chretien 24 inch telescope capable of tracking objects through the zenith without axes rotation delay (no Dead Zone). This paper describes enhancement components added to the quad axis mount telescope that will enable measurements supporting novel research and field testing focused on `three-dimensional' characterization of turbulent atmospheres, mitigation techniques, and new sensing modalities. These all support research and operational techniques relating to astronomical imaging and electro-optical propagation though the atmosphere, relative to sub-meter class telescopes in humid, continental environments. This effort will use custom designed and commercial off the shelf hardware; sub-system components discussed will include a wavefront sensor system, a co-aligned beam launch system, and a fiber coupled research laser. The wavefront sensing system has the ability to take measurements from a dynamic altitude adjustable laser beacon scattering spot, a key concept that enables rapid turbulence structure parameter measurements over an altitude varied integrated atmospheric volume. The sub-components are integrated with the overall goal of measuring a height-resolved volumetric profile for the atmospheric turbulence structure parameter at the site, and developing mobile techniques for such measurements. The design concept, part selection optimization, baseline component lab testing, and initial field measurements, will be discussed in the main sections of this paper. This project is a collaborative effort between the Air Force Research Labs Sensors Directorate and the Air Force Institute of Technology Center for Directed Energy.

  4. Building and strengthening infrastructure for data exchange: lessons from the beacon communities.

    Science.gov (United States)

    Torres, Gretchen W; Swietek, Karen; Ubri, Petry S; Singer, Rachel F; Lowell, Kristina H; Miller, Wilhelmine

    2014-01-01

    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. 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. 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. 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 fostering transparent governance and stewardship

  5. Time-Resolved Nucleic Acid Hybridization Beacons Utilizing Unimolecular and Toehold-Mediated Strand Displacement Designs.

    Science.gov (United States)

    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

  6. Molecular beacon anchored onto a graphene oxide substrate

    Science.gov (United States)

    Darbandi, Arash; Datta, Debopam; Patel, Krunal; Lin, Gary; Stroscio, Michael A.; Dutta, Mitra

    2017-09-01

    In this article, we report a graphene oxide-based nanosensor incorporating semiconductor quantum dots linked to DNA-aptamers that functions as a ‘turn-off’ fluorescent nanosensor for detection of low concentrations of analytes. A specific demonstration of this turn-off aptasensor is presented for the case of the detection of mercury (II) ions. In this system, ensembles of aptamer-based quantum-dot sensors are anchored onto graphene oxide (GO) flakes which provide a platform for analyte detection in the vicinity of GO. Herein, the operation of this ensemble-based nanosensor is demonstrated for mercury ions, which upon addition of mercury, quenching of the emission intensity from the quantum dots is observed due to resonance energy transfer between quantum dots and the gold nanoparticle connected via a mercury target aptamer. A key result is that the usually dominant effect of quenching of the quantum dot due to close proximity to the GO can be reduced to negligible levels by using a linker molecule in conjunctions with the aptamer-based nanosensor. The effect of ionic concentration of the background matrix on the emission intensity was also investigated. The sensor system is found to be highly selective towards mercury and exhibits a linear behavior (r 2 > 0.99) in the nanomolar concentration range. The detection limit of the sensor towards mercury with no GO present was found to be 16.5 nM. With GO attached to molecular beacon via 14 base, 35 base, and 51 base long linker DNA, the detection limit was found to be 38.4 nM, 9.45 nM, and 11.38 nM; respectively.

  7. A complementary palette of NanoCluster Beacons.

    Science.gov (United States)

    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.

  8. Detection of organic matter in interstellar grains.

    Science.gov (United States)

    Pendleton, Y J

    1997-06-01

    Star formation and the subsequent evolution of planetary systems occurs in dense molecular clouds, which are comprised, in part, of interstellar dust grains gathered from the diffuse interstellar medium (DISM). Radio observations of the interstellar medium reveal the presence of organic molecules in the gas phase and infrared observational studies provide details concerning the solid-state features in dust grains. In particular, a series of absorption bands have been observed near 3.4 microns (approximately 2940 cm-1) towards bright infrared objects which are seen through large column densities of interstellar dust. Comparisons of organic residues, produced under a variety of laboratory conditions, to the diffuse interstellar medium observations have shown that aliphatic hydrocarbon grains are responsible for the spectral absorption features observed near 3.4 microns (approximately 2940 cm-1). These hydrocarbons appear to carry the -CH2- and -CH3 functional groups in the abundance ratio CH2/CH3 approximately 2.5, and the amount of carbon tied up in this component is greater than 4% of the cosmic carbon available. On a galactic scale, the strength of the 3.4 microns band does not scale linearly with visual extinction, but instead increases more rapidly for objects near the Galactic Center. A similar trend is noted in the strength of the Si-O absorption band near 9.7 microns. The similar behavior of the C-H and Si-O stretching bands suggests that these two components may be coupled, perhaps in the form of grains with silicate cores and refractory organic mantles. The ubiquity of the hydrocarbon features seen in the near infrared near 3.4 microns throughout out Galaxy and in other galaxies demonstrates the widespread availability of such material for incorporation into the many newly forming planetary systems. The similarity of the 3.4 microns features in any organic material with aliphatic hydrocarbons underscores the need for complete astronomical observational

  9. A transfection reporter for the prevention of false-negative results in molecular beacon experiments.

    Science.gov (United States)

    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. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Code Development and Analysis Program: developmental checkout of the BEACON/MOD2A code. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Ramsthaler, J. A.; Lime, J. F.; Sahota, M. S.

    1978-12-01

    A best-estimate transient containment code, BEACON, is being developed by EG and G Idaho, Inc. for the Nuclear Regulatory Commission's reactor safety research program. This is an advanced, two-dimensional fluid flow code designed to predict temperatures and pressures in a dry PWR containment during a hypothetical loss-of-coolant accident. The most recent version of the code, MOD2A, is presently in the final stages of production prior to being released to the National Energy Software Center. As part of the final code checkout, seven sample problems were selected to be run with BEACON/MOD2A.

  11. Interstellar Probe: The Next Step To Flight

    Science.gov (United States)

    McNutt, Ralph; Zurbuchen, Thomas H.

    2016-07-01

    In the years following the discovery of the solar wind, the term "heliosphere" was coined and defined as "the region of interplanetary space where the solar wind is flowing supersonically." In June 1971, with the development of the Pioneer probes to Jupiter and beyond well underway, a session of the American Astronautical Society meeting considered scientific exploration reaching beyond the solar system and into the interstellar medium. Despite many discussions, studies, and meetings since, the most recent held under the auspices of the Keck Institute for Space Studies (8-11 September 2014 and 13-15 January 2015), such missions have been relegated to the '"future" due to the large distances and solar system escape speeds contemplated for their execution. In the meantime, the Voyager Interstellar Mission (VIM), consisting of the twin Voyager spacecraft almost 40 years since their respective launches, are making inroads into this region beyond the termination shock of the solar wind, a new region of the solid bodies of the solar system has been opened by the New Horizons flyby of the Pluto system, and the Cassini Ion and Neutral CAmera (INCA) and Interstellar Boundary Explorer (IBEX) have remotely sensed neutral atoms that have provided significant clues to the global structure of the interaction of the solar wind and interstellar medium. It is now time for a dedicated mission to the regime beyond the solar system to explore our galactic environment. A first, near-term implementation can be carried out with the near-current flight system technology. What is also clear is that the high speeds required will limit the spacecraft to a relatively small mass of no more than ~500 kg, regardless of the propulsion details. The recent success of the New Horizons mission at the Pluto system illustrates that with modern technologies, such spacecraft sizes can still accommodate the means to produce paradigm-shifting science, providing for a compelling scientific mission. The

  12. The utah beacon experience: integrating quality improvement, health information technology, and practice facilitation to improve diabetes outcomes in small health care facilities.

    Science.gov (United States)

    Tennison, Janet; Rajeev, Deepthi; Woolsey, Sarah; Black, Jeff; Oostema, Steven J; North, Christie

    2014-01-01

    The Utah Improving Care through Connectivity and Collaboration (IC3) Beacon community (2010-2013) was spearheaded by HealthInsight, a nonprofit, community-based organization. One of the main objectives of IC(3) was to improve health care provided to patients with diabetes in three Utah counties, collaborating with 21 independent smaller clinics and two large health care enterprises. This paper will focus on the use of health information technology (HIT) and practice facilitation to develop and implement new care processes to improve clinic workflow and ultimately improve patients' diabetes outcomes at 21 participating smaller, independent clinics. Early in the project, we learned that most of the 21 clinics did not have the resources needed to successfully implement quality improvement (QI) initiatives. IC(3) helped clinics effectively use data generated from their electronic health records (EHRs) to design and implement interventions to improve patients' diabetes outcomes. This close coupling of HIT, expert practice facilitation, and Learning Collaboratives was found to be especially valuable in clinics with limited resources. Through this process we learned that (1) an extensive readiness assessment improved clinic retention, (2) clinic champions were important for a successful collaboration, and (3) current EHR systems have limited functionality to assist in QI initiatives. In general, smaller, independent clinics lack knowledge and experience with QI and have limited HIT experience to improve patient care using electronic clinical data. Additionally, future projects like IC(3) Beacon will be instrumental in changing clinic culture so that QI is integrated into routine workflow. Our efforts led to significant changes in how practice staff optimized their EHRs to manage and improve diabetes care, while establishing the framework for sustainability. Some of the IC(3) Beacon practices are currently smoothly transitioning to new models of care such as Patient

  13. Turbulence and the ionization of interstellar gas

    Science.gov (United States)

    Hill, Alex S.

    2015-08-01

    Turbulence is widely observed in the ionized gas in the interstellar media of star-forming galaxies. Observations in the Milky Way indicate emission from that the warm ionized medium -- ionized gas far from massive stars, the most likely source of the ionization -- has a lognormal intensity distribution. This and other measurements indicate that the gas is well-described as a transonic turbulent fluid. Such a fluid can be produced by feedback from supernovae in the Galaxy. Understanding of this turbulence has also led to a natural explanation for a long-standing puzzle: how do ionizing photons travel through the largely-neutral interstellar medium and produce the ionization? In the turbulent gas, low-density pathways allow ionizing photons to propagate for kiloparsecs, with implications for radiative energy transport in star-forming galaxies.

  14. Human factors issues for interstellar spacecraft

    Science.gov (United States)

    Cohen, Marc M.; Brody, Adam R.

    1991-01-01

    Developments in research on space human factors are reviewed in the context of a self-sustaining interstellar spacecraft based on the notion of traveling space settlements. Assumptions about interstellar travel are set forth addressing costs, mission durations, and the need for multigenerational space colonies. The model of human motivation by Maslow (1970) is examined and directly related to the design of space habitat architecture. Human-factors technology issues encompass the human-machine interface, crew selection and training, and the development of spaceship infrastructure during transtellar flight. A scenario for feasible instellar travel is based on a speed of 0.5c, a timeframe of about 100 yr, and an expandable multigenerational crew of about 100 members. Crew training is identified as a critical human-factors issue requiring the development of perceptual and cognitive aids such as expert systems and virtual reality.

  15. Interstellar molecules - Formation in solar nebulae

    Science.gov (United States)

    Anders, E.

    1973-01-01

    Herbig's (1970) hypothesis that solar nebulae might be the principal source of interstellar grains and molecules is investigated. The investigation includes the determination of physical and chemical conditions in the early solar system. The production of organic compounds in the solar nebula is studied, and the compounds in meteorites are compared with those obtained in Miller-Urey and Fischer-Tropsch-type (FTT) reactions, taking into consideration aliphatic hydrocarbons, aromatic hydrocarbons, purines, pyrimidines, amino acids, porphyrins, and aspects of carbon-isotope fractionation. It is found that FTT reactions account reasonably well for all well-established features of organic matter in meteorites investigated. The distribution of compounds produced by FTT reactions is compared with the distribution of interstellar molecules. Biological implications of the results are considered.

  16. Organic Synthesis in Simulated Interstellar Ice Analogs

    Science.gov (United States)

    Dworkin, Jason P.; Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.; Deamer, David W.; Elsila, Jamie; Zare, Richard N.

    2001-01-01

    Comets and carbonaceous micrometeorites may have been significant sources of organic compounds on the early Earth. Ices on grains in interstellar dense molecular clouds contain a variety of simple molecules as well as aromatic molecules of various sizes. While in these clouds the icy grains are processed by ultraviolet light and cosmic radiation which produces more complex organic molecules. We have run laboratory simulations to identify the types of molecules which could have been generated photolytically in pre-cometary ices. Experiments were conducted by forming various realistic interstellar mixed-molecular ices with and without polycyclic aromatic hydrocarbons (PAHs) at approx. 10 K under high vacuum irradiated with UV light from a hydrogen plasma lamp. The residue that remained after warming to room temperature was analyzed by HPLC, and by laser desorption mass spectrometry. The residue contains several classes of compounds which may be of prebiotic significance.

  17. Interstellar Turbulence II: Implications and Effects

    CERN Document Server

    Scalo, J

    2004-01-01

    Interstellar turbulence has implications for the dispersal and mixing of the elements, cloud chemistry, cosmic ray scattering, and radio wave propagation through the ionized medium. This review discusses the observations and theory of these effects. Metallicity fluctuations are summarized, and the theory of turbulent transport of passive tracers is reviewed. Modeling methods, turbulent concentration of dust grains, and the turbulent washout of radial abundance gradients are discussed. Interstellar chemistry is affected by turbulent transport of various species between environments with different physical properties and by turbulent heating in shocks, vortical dissipation regions, and local regions of enhanced ambipolar diffusion. Cosmic rays are scattered and accelerated in turbulent magnetic waves and shocks, and they generate turbulence on the scale of their gyroradii. Radio wave scintillation is an important diagnostic for small scale turbulence in the ionized medium, giving information about the power spe...

  18. Structural Evolution of Interstellar Polycyclic Aromatic Hydrocarbons

    Science.gov (United States)

    Hammonds, Mark; Candian, Alessandra; Mori, Tamami; Usui, Fumihiko; Onaka, Takashi

    2015-08-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are an important reservoir for molecular carbon in the interstellar medium (ISM), and investigations into their chemistry and behaviour may be important to the understanding of how carbon is processed from simple forms into complex prebiotic molecules such as those detected in chondritic meteorites. In this study, infrared astronomical data from AKARI and other observatories are used together with laboratory and theoretical data to study variations in the structure of emitting PAHs in interstellar environments using spectroscopic decomposition techniques and bands arising from carbon-hydrogen bond vibrations at wavelengths from 3 - 14 microns. Results and inferences are discussed in terms of the processing of large carbonaceous molecules in astrophysical environments.

  19. Interstellar Gas and a Dark Disk

    Science.gov (United States)

    Kramer, Eric David; Randall, Lisa

    2016-10-01

    We introduce a potentially powerful method for constraining or discovering a thin dark matter disk in the Milky Way. The method relies on the relationship between the midplane densities and scale heights of interstellar gas being determined by the gravitational potential, which is sensitive to the presence of a dark disk. We show how to use the interstellar gas parameters to set a bound on a dark disk and discuss the constraints suggested by the current data. However, current measurements for these parameters are discordant, with the uncertainty in the constraint being dominated by the molecular hydrogen midplane density measurement, as well as by the atomic hydrogen velocity dispersion measurement. Magnetic fields and cosmic ray pressure, which are expected to play a role, are uncertain as well. The current models and data are inadequate to determine the disk's existence, but taken at face value, may favor its existence depending on the gas parameters used.

  20. Star Formation in Turbulent Interstellar Gas

    CERN Document Server

    Klessen, R S

    2003-01-01

    Understanding the star formation process is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that supersonic interstellar turbulence rather than magnetic fields controls star formation. Supersonic turbulence can provide support against gravitational collapse on global scales, while at the same time it produces localized density enhancements that allow for collapse on small scales. The efficiency and timescale of stellar birth in Galactic molecular clouds strongly depend on the properties of the interstellar turbulent velocity field, with slow, inefficient, isolated star formation being a hallmark of turbulent support, and fast, efficient, clustered star formation occurring in its absence.

  1. Organic Synthesis in Simulated Interstellar Ice Analogs

    Science.gov (United States)

    Dworkin, Jason P.; Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.; Deamer, David W.; Elsila, Jamie; Zare, Richard N.

    2001-01-01

    Comets and carbonaceous micrometeorites may have been significant sources of organic compounds on the early Earth. Ices on grains in interstellar dense molecular clouds contain a variety of simple molecules as well as aromatic molecules of various sizes. While in these clouds the icy grains are processed by ultraviolet light and cosmic radiation which produces more complex organic molecules. We have run laboratory simulations to identify the types of molecules which could have been generated photolytically in pre-cometary ices. Experiments were conducted by forming various realistic interstellar mixed-molecular ices with and without polycyclic aromatic hydrocarbons (PAHs) at approx. 10 K under high vacuum irradiated with UV light from a hydrogen plasma lamp. The residue that remained after warming to room temperature was analyzed by HPLC, and by laser desorption mass spectrometry. The residue contains several classes of compounds which may be of prebiotic significance.

  2. Local Interstellar Magnetic Field Determined from the Interstellar Boundary Explorer Ribbon

    Science.gov (United States)

    Zirnstein, E. J.; Heerikhuisen, J.; Funsten, H. O.; Livadiotis, G.; McComas, D. J.; Pogorelov, N. V.

    2016-02-01

    The solar wind emanating from the Sun interacts with the local interstellar medium (LISM), forming the heliosphere. Hydrogen energetic neutral atoms (ENAs) produced by the solar-interstellar interaction carry important information about plasma properties from the boundaries of the heliosphere, and are currently being measured by NASA's Interstellar Boundary Explorer (IBEX). IBEX observations show the existence of a “ribbon” of intense ENA emission projecting a circle on the celestial sphere that is centered near the local interstellar magnetic field (ISMF) vector. Here we show that the source of the IBEX ribbon as a function of ENA energy outside the heliosphere, uniquely coupled to the draping of the ISMF around the heliopause, can be used to precisely determine the magnitude (2.93 ± 0.08 μG) and direction (227.°28 ± 0.°69, 34.°62 ± 0.°45 in ecliptic longitude and latitude) of the pristine ISMF far (∼1000 AU) from the Sun. We find that the ISMF vector is offset from the ribbon center by ∼8.°3 toward the direction of motion of the heliosphere through the LISM, and their vectors form a plane that is consistent with the direction of deflected interstellar neutral hydrogen, thought to be controlled by the ISMF. Our results yield draped ISMF properties close to that observed by Voyager 1, the only spacecraft to directly measure the ISMF close to the heliosphere, and give predictions of the pristine ISMF that Voyager 1 has yet to sample.

  3. Kinetic chemistry of dense interstellar clouds

    Energy Technology Data Exchange (ETDEWEB)

    Graedel, T.E.; Langer, W.D.; Frerking, M.A.

    1982-03-01

    A detailed model of the time-dependent chemistry of dense interstellar clouds has been developed to study the dominant chemical processes in carbon and oxygen isotope fractionation, formation of nitrogen-containing molecules, evolution of product molecules as a function of cloud density and temperature, and other topics of interest. The full computation involves 328 individual reactions (expanded to 1067 to study carbon and oxygen isotope chemistry); photodegradation processes are unimportant in these dense clouds and are excluded.

  4. TAU as Tao. [interstellar spacecraft performance

    Science.gov (United States)

    Lyman, P. T.; Reid, M. S.

    1989-01-01

    This paper discusses the feasibility of building and launching a truly deep-space spacecraft mission that will penetrate near interstellar space to a depth of one thousand astronomical units (TAU) within a flight time of 50 years. Particular attention is given to the mission profile and to its communications system, power system, and propulsion system. Results of experimental studies indicate that, with advanced technology, reasonable trip times can be achieved and adequate science information can be brought to earth.

  5. Building Interstellar's black hole: the gravitational renderer

    OpenAIRE

    James, Oliver; Dieckmann, Sylvan; Pabst, Simon; Roberts, Paul-George H.; Thorne, Kip S.

    2015-01-01

    Interstellar is the first feature film to attempt depicting a black hole as it would actually be seen by somebody nearby. A close collaboration between the production's Scientific Advisor and the Visual Effects team led to the development of a new renderer, DNGR (Double Negative Gravitational Renderer) which uses novel techniques for rendering in curved space-time. Following the completion of the movie, the code was adapted for scientific research, leading to new insights into gravitational l...

  6. Diffuse interstellar bands in M33

    CERN Document Server

    Smith, Keith T; Evans, Christopher J; Cox, Nick L J; Sarre, Peter J

    2013-01-01

    We present the first sample of diffuse interstellar bands (DIBs) in the nearby galaxy M33. Studying DIBs in other galaxies allows the behaviour of the carriers to be examined under interstellar conditions which can be quite different from those of the Milky Way, and to determine which DIB properties can be used as reliable probes of extragalactic interstellar media. Multi-object spectroscopy of 43 stars in M33 has been performed using Keck/DEIMOS. The stellar spectral types were determined and combined with literature photometry to determine the M33 reddenings E(B-V)_M33. Equivalent widths or upper limits have been measured for the {\\lambda}5780 DIB towards each star. DIBs were detected towards 20 stars, demonstrating that their carriers are abundant in M33. The relationship with reddening is found to be at the upper end of the range observed in the Milky Way. The line of sight towards one star has an unusually strong ratio of DIB equivalent width to E(B-V)_M33, and a total of seven DIBs were detected towards...

  7. Airborne and laboratory studies of interstellar PAHs

    Science.gov (United States)

    Allamandola, L. J.; Sandford, S. A.; Hudgins, D. M.; Witteborn, Fred C.

    1995-01-01

    A brief history of the observations which have led to the hypothesis that polycyclic aromatic hydrocarbons (PAH's) are the carriers of the widespread interstellar emission features near 3050, 1615, '1300' and 890 cm(exp -1) (3.29, 6.2, '7.7', and 11.2 mu m) is presented. The central role of airborne spectroscopy is stressed. The principal reason for the assignment to PAH's was the resemblance of the interstellar emission spectrum to the laboratory absorption spectra of PAH's and PAH-like materials. Since precious little information was available on the properties of PAH's in the forms that are thought to exist under interstellar conditions -isolated and ionized in the emission zones, with the smallest PAH's being dehydrogenated- there was a need for a spectral data base on PAH's taken in these states. Here, the relevant infrared spectroscopic properties of PAH's will be reviewed. These laboratory spectra show that relative band intensities are severely altered and that band frequencies shift. It is shown that these new data alleviate several of the spectroscopic criticisms previously leveled at the hypothesis.

  8. Extra-Galactic Diffuse Interstellar Bands

    Science.gov (United States)

    Cox, N.; Ehrenfreund, Pascale; Kaper, Lex; Spaans, Marco; Foing, Bernard

    Diffuse Interstellar Bands (DIBs) have been observed ubiquitously along many sight-lines probing the interstellar medium of the Milky Way. Despite extensive efforts, their carrier(s) have not yet been identified, although they are very likely of a carbonaceous nature and reside in the gas phase. Possible candidates include, but are not limited to, polycyclic aromatic hydro- carbons (PAHs), fullerenes and carbon chains. To advance our understanding of DIB behaviour and thus DIB carrier properties we need to study environments inherently different from those observed in the Milky Way. Only recent advances in instrumentation and telescope capabilities are providing us with new exciting possibilities for extra-galactic DIB research. We present here a selection of our recent observational results for (extra)-galactic DIBs in the Local Group and beyond. In particular, DIBs in the Magellanic Clouds and in the spiral galaxy NGC1448. These first results show surprising similarities between certain DIB profiles as well as differences in DIB behaviour. Understanding diffuse cloud chemistry, in particular with respect to complex (carbonaceous) molecules, is crucial to any DIB carrier identification. In this respect, external galaxies offer a unique window as they exhibit local interstellar conditions (such as metallicity, UV-field and gas-to-dust ratio) very different from those observed in the Milky Way. We discuss briefly the effect of metallicity and the gas-to-dust ratio on the physi-chemical properties of diffuse clouds and the subsequent effects on the PAH charge state distribution and the DIB carriers.

  9. Sensitive HIV-1 detection in a homogeneous solution based on an electrochemical molecular beacon coupled with a nafion-graphene composite film modified screen-printed carbon electrode.

    Science.gov (United States)

    Li, Bo; Li, Zhengliang; Situ, Bo; Dai, Zong; Liu, Qinlan; Wang, Qian; Gu, Dayong; Zheng, Lei

    2014-02-15

    A novel electrochemical sensing assay for sensitive determination of HIV-1 in a homogeneous solution has been developed using an electrochemical molecular beacon combined with a nafion-graphene composite film modified screen-printed carbon electrode (nafion-graphene/SPCE). The electrochemical molecular beacon (CAs-MB), comprising a special recognition sequence for the conserved region of the HIV-1 gag gene and a pair of carminic acid molecules as a marker, can indicate the presence of the HIV-1 target by its on/off electrochemical signal behavior. It is suitable for direct, electrochemical determination of HIV-1, thereby simplifying the detection procedure and improving the signal-to-noise (S/N) ratio. To further improve the sensitivity, the nafion-graphene/SPCE was used to monitor changes in the CAs-MB, which has notable advantages, such as being ultrasensitive, inexpensive, and disposable. Under optimized conditions, the peak currents showed a linear relationship with the logarithm of target oligonucleotide concentrations ranging from 40 nM to 2.56 μM, with a detection limit of 5 nM (S/N=3). This sensing assay also displays a good stability, with a recovery of 88-106.8% and RSD<7% (n=5) in real serum samples. This work may lead to the development of an effective method for early point-of-care diagnosis of HIV-1 infection.

  10. Geologic map of the Beacon Rock quadrangle, Skamania County, Washington

    Science.gov (United States)

    Evarts, Russell C.; Fleck, Robert J.

    2017-06-06

    The Beacon Rock 7.5′ quadrangle is located approximately 50 km east of Portland, Oregon, on the north side of the Columbia River Gorge, a scenic canyon carved through the axis of the Cascade Range by the Columbia River. Although approximately 75,000 people live within the gorge, much of the region remains little developed and is encompassed by the 292,500-acre Columbia River Gorge National Scenic Area, managed by a consortium of government agencies “to pro­tect and provide for the enhancement of the scenic, cultural, recreational and natural resources of the Gorge and to protect and support the economy of the Columbia River Gorge area.” As the only low-elevation corridor through the Cascade Range, the gorge is a critical regional transportation and utilities corridor (Wang and Chaker, 2004). Major state and national highways and rail lines run along both shores of the Columbia River, which also provides important water access to ports in the agricultural interior of the Pacific Northwest. Transmission lines carry power from hydroelectric facilities in the gorge and farther east to the growing urban areas of western Oregon and Washington, and natural-gas pipelines transect the corridor (Wang and Chaker, 2004). These lifelines are highly vulnerable to disruption by earthquakes, landslides, and floods. A major purpose of the work described here is to identify and map geologic hazards, such as faults and landslide-prone areas, to provide more accurate assessments of the risks associated with these features.The steep canyon walls of the map area reveal exten­sive outcrops of Miocene flood-basalt flows of the Columbia River Basalt Group capped by fluvial deposits of the ances­tral Columbia River, Pliocene lavas erupted from the axis of the Cascade arc to the east, and volcanic rocks erupted from numerous local vents. The Columbia River Basalt Group unconformably rests on a sequence of late Oligocene and early Miocene rocks of the ancestral Cascade volcanic arc

  11. Fusing Range Measurements from Ultrasonic Beacons and a Laser Range Finder for Localization of a Mobile Robot

    Science.gov (United States)

    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

  12. Baseline characteristics in the Bardoxolone methyl EvAluation in patients with Chronic kidney disease and type 2 diabetes mellitus: the Occurrence of renal eveNts (BEACON) trial.

    Science.gov (United States)

    Lambers Heerspink, Hiddo J; Chertow, Glenn M; Akizawa, Tadao; Audhya, Paul; Bakris, George L; Goldsberry, Angie; Krauth, Melissa; Linde, Peter; McMurray, John J; Meyer, Colin J; Parving, Hans-Henrik; Remuzzi, Giuseppe; Christ-Schmidt, Heidi; Toto, Robert D; Vaziri, Nosratola D; Wanner, Christoph; Wittes, Janet; Wrolstad, Danielle; de Zeeuw, Dick

    2013-11-01

    Type 2 diabetes mellitus (T2DM) is the most important contributing cause of end-stage renal disease (ESRD) worldwide. Bardoxolone methyl, a nuclear factor-erythroid-2-related factor 2 activator, augments estimated glomerular filtration. The Bardoxolone methyl EvAluation in patients with Chronic kidney disease and type 2 diabetes mellitus: the Occurrence of renal eveNts (BEACON) trial was designed to establish whether bardoxolone methyl slows or prevents progression to ESRD. Herein, we describe baseline characteristics of the BEACON population. BEACON is a randomized double-blind placebo-controlled clinical trial in 2185 patients with T2DM and chronic kidney disease stage 4 (eGFR between 15 and 30 mL/min/1.73 m(2)) designed to test the hypothesis that bardoxolone methyl added to guideline-recommended treatment including inhibitors of the renin-angiotensin-aldosterone system slows or prevents progression to ESRD or cardiovascular death compared with placebo. Baseline characteristics (mean or percentage) of the population include age 68.5 years, female 43%, Caucasian 78%, eGFR 22.5 mL/min/1.73 m(2) and systolic/diastolic blood pressure 140/70 mmHg. The median urinary albumin:creatinine ratio was 320 mg/g and the frequency of micro- and macroalbuminuria was 30 and 51%, respectively. Anemia, abnormalities in markers of bone metabolism and elevations in cardiovascular biomarkers were frequently observed. A history of cardiovascular disease was present in 56%, neuropathy in 47% and retinopathy in 41% of patients. The BEACON trial enrolled a population heretofore unstudied in an international randomized controlled trial. Enrolled patients suffered with numerous co-morbid conditions and exhibited multiple laboratory abnormalities, highlighting the critical need for new therapies to optimize management of these conditions.

  13. A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs.

    Science.gov (United States)

    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.

  14. Aplicació de seguiment i visualització de dispositus iBeacon

    OpenAIRE

    2015-01-01

    Els beacons són dispositius que emeten senyal bluetooth low energy (BLE) de manera contínua durant un llarg període de temps. Aquesta jove i emergent tecnologia esta cridada a ser una revolució en molts camps de la nostra vida diària.

  15. A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs

    Science.gov (United States)

    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

  16. Improved fixation quality provided by a Bessel beacon in an adaptive optics system.

    Science.gov (United States)

    Lambert, Andrew J; Daly, Elizabeth M; Dainty, Christopher J

    2013-07-01

    We investigate whether a structured probe beam that creates the beacon for use in a retinal imaging adaptive optics system can provide useful side effects. In particular we investigate whether a Bessel beam that is seen by the subject as a set of concentric rings has a dampening effect on fixation variations of the subject under observation. This calming effect would allow longer periods of observation, particularly for patients with abnormal fixation. An experimental adaptive optics system developed for retinal imaging is used to monitor the fluctuations in aberrations for artificial and human subjects. The probe beam is alternated between a traditional beacon and one provided by a Bessel beam created by SLM. Time-frequency analysis is used to indicate the differences in power and time variation during fixation depending on whether the Bessel beam or the traditional beacon is employed. Comparison is made with the response for an artificial eye to discount systemic variations. Significant evidence is accrued to indicate the reduced fluctuations in fixation when the Bessel beam is employed to create the beacon. © 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

  17. Beacon-Based Service Publishing Framework in Multiservice Wi-Fi Hotspots

    Directory of Open Access Journals (Sweden)

    Di Sorte Dario

    2007-01-01

    Full Text Available In an expected future multiaccess and multiservice IEEE 802.11 environment, the problem of providing users with useful service-related information to support a correct rapid network selection is expected to become a very important issue. A feasible short-term 802.11-tailored working solution, compliant with existing equipment, is to publish service information encoded within the SSID information element within beacon frames. This makes it possible for an operator to implement service publishing in 802.11 networks while waiting for a standardized mechanism. Also, this straightforward approach has allowed us to evaluate experimentally the performance of a beacon-based service publishing solution. In fact, the main focus of the paper is indeed to present a quantitative comparison of service discovery times between the legacy scenario, where the user is forced to associate and authenticate with a network point of access to check its service offer, and the enhanced scenario where the set of service-related information is broadcasted within beacons. These discovery times are obtained by processing the results of a measurement campaign performed in a multiaccess/service 802.11 environment. This analysis confirms the effectiveness of the beacon-based approach. We also show that the cost in terms of wireless bandwidth consumption of such solution is low.

  18. Molecular beacon nanosensors for live cell detection and tracking differentiation and reprogramming

    DEFF Research Database (Denmark)

    Ilieva, Mirolyuba

    2013-01-01

    cell level is molecular beacons (MBs). They are stem-loop structured antisense oligonucleotide probes labelled with a reporter fluorophore at one end and with quencher at the other end. Upon hybridization with complementary target, hydrogen bonds between stem nucleotide bases brake, resulting...

  19. Beacon signal in transcranial color coded ultrasound: A sign for brain death

    Directory of Open Access Journals (Sweden)

    Mehmet Akif Topçuoğlu

    2014-04-01

    Full Text Available A widely under-recognized brain-death confirming transcranial ultrasonography pattern resembling the red-blue beacon signal was demonstrated. Familiarity to this distinct and characteristic ultrasonic pattern seems to be important in the perspective of point-of-care neurological ultrasound use and knobology.

  20. Scheduled MAC in Beacon Overlay Networks for Underwater Localization and Time-Synchronization

    NARCIS (Netherlands)

    van Kleunen, W.A.P.; Meratnia, Nirvana; Havinga, Paul J.M.

    2011-01-01

    In this article we introduce a MAC protocol designed for underwater localization and time-synchronisation. The MAC protocol assumes a network of static reference nodes and allows blind nodes to be localized by listening-only to the beacon messages. Such a system is known to be very scalable. We show

  1. Analysis and Enhancement of IEEE 802.15.4e DSME Beacon Scheduling Model

    Directory of Open Access Journals (Sweden)

    Kwang-il Hwang

    2014-01-01

    Full Text Available In order to construct a successful Internet of things (IoT, reliable network construction and maintenance in a sensor domain should be supported. However, IEEE 802.15.4, which is the most representative wireless standard for IoT, still has problems in constructing a large-scale sensor network, such as beacon collision. To overcome some problems in IEEE 802.15.4, the 15.4e task group proposed various different modes of operation. Particularly, the IEEE 802.15.4e deterministic and synchronous multichannel extension (DSME mode presents a novel scheduling model to solve beacon collision problems. However, the DSME model specified in the 15.4e draft does not present a concrete design model but a conceptual abstract model. Therefore, in this paper we introduce a DSME beacon scheduling model and present a concrete design model. Furthermore, validity and performance of DSME are evaluated through experiments. Based on experiment results, we analyze the problems and limitations of DSME, present solutions step by step, and finally propose an enhanced DSME beacon scheduling model. Through additional experiments, we prove the performance superiority of enhanced DSME.

  2. The Effects of a Rectangular Rapid-Flashing Beacon on Vehicle Speed

    Science.gov (United States)

    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…

  3. Sequential strand displacement beacon for detection of DNA coverage on functionalized gold nanoparticles.

    Science.gov (United States)

    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. A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs.

    Directory of Open Access Journals (Sweden)

    Yuanfu Mo

    Full Text Available 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.

  5. Reliable beacon transmission based MAC protocol for LR-WPANs over WLAN interferences

    Institute of Scientific and Technical Information of China (English)

    Ji-Hoon PARK; Byung-Seo KIM

    2014-01-01

    The use of IEEE 802.15.4 standard based application systems has been rapidly increasing, for example, in medical services, sensor networks, public safety systems, and home automation systems. However, issues arise from the fact that IEEE 802.15.4 standard based low rate wireless personal area networks (LR-WPANs) use the same frequency bands as wireless local area networks (WLANs), and they interfere with each other. Based on past research on this issue, the interference has a more serious impact on LR-WPANs’ performance than on WLANs’ performance. In this paper we propose a method to improve LR-WPANs’ performance while coexisting with WLANs, which is called the reliable beacon transmission based medium access control (MAC) protocol. Since the reliability of a beacon frame is important, in this method, only the beacon frame is transmitted in interference-free channels, and the data packets are transmitted in interfered channels instead of abandoning the channels altogether. This method increases the reliability of beacon frames as well as overall channel utilizations. The effectiveness of the proposed method was evaluated through extensive simulations, and this paper proves that this method improves the performance of IEEE 802.15.4 based wireless sensor networks (WSNs) over WLANs’ interferences.

  6. The Effects of a Rectangular Rapid-Flashing Beacon on Vehicle Speed

    Science.gov (United States)

    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…

  7. Genotyping Single Nucleotide Polymorphisms Using Different Molecular Beacon Multiplexed within a Suspended Core Optical Fiber

    Directory of Open Access Journals (Sweden)

    Linh Viet Nguyen

    2014-08-01

    Full Text Available 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.

  8. Leveraging Health IT to Reduce Disparities in Three Underserved Beacon Communities.

    Science.gov (United States)

    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.

  9. Impacts of Fog Characteristics, Forward Illumination, and Warning Beacon Intensity Distribution on Roadway Hazard Visibility.

    Science.gov (United States)

    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.

  10. A nanocluster beacon based on the template transformation of DNA-templated silver nanoclusters.

    Science.gov (United States)

    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.

  11. Single-cell detection of mRNA expression using nanofountain-probe electroporated molecular beacons.

    Science.gov (United States)

    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.

  12. Working Together To Build Beacon Centers in San Francisco: Evaluation Findings from 1998-2000.

    Science.gov (United States)

    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…

  13. Visual detection of STAT5B gene expression in living cell using the hairpin DNA modified gold nanoparticle beacon.

    Science.gov (United States)

    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. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. New Large Interstellar Molecules Detected with the GBT

    Science.gov (United States)

    Hollis, Jan M.

    2005-01-01

    At present, more than 135 different molecules have been identified in interstellar clouds. The newest instrument in the interstellar molecule search arsenal is the recently commissioned Green Bank Telescope (GBT). In 2004, the large aldehydes propenal (CH2CHCHO) and propanal (CH3CH2CHO) were the first new interstellar molecules discovered with the GBT. At the same time, the GBT was used to observe interstellar glycolaldehyde (CH2OHCHO), which is the simplest possible aldehyde sugar; interstellar ethylene glycol (HOCH2CH2OH), which is the sugar alcohol of glycolaldehyde; and interstellar methylcyanodiacetylene (CH3C5N). These new GBT observations suggest that successive atomic addition reactions are common in the formation of larger related species. The observations will be presented and discussed.

  15. The Ingenious Theory of Interstellar Trade

    Science.gov (United States)

    Radhakrishnan, Arun; Ganapathy, Rohan M.

    This paper extends interplanetary trade theory to an interstellar setting. It is chiefly concerned with the following question: How should interest charges on goods in transit be computed when the goods travel at speeds close to the actual speed of light? This is a problem because the time taken in transit will appear less to an observer travelling with the goods than to a stationary observer. An innovative and ingenious solution is derived from the economic theory, and two useless but TRUE theorems are proved. The interstellar trade would happen in such a way that two time frames must be considered namely that of the stationary observer whose time runs faster compared to the time frame of the observer in transit The interest in a given trade is purely based on the time taken for the debtor to pay the amount, once the goods have been delivered by the seller. But, in case of interstellar trade, the interest to be calculated in between two time frames would lead to the question of which time frame to be considered and moreover, the time taken for the goods to reach the destination is signicantly prolonged compared to the interplanetary trade, which means, even the slightest variations in the interest rate would be magnied. Apart from this, various new factors arise while calculating the interest. The factors include the time value of money, and the risk of variation in demand for goods, the risk of interspace accidents causing loss of the goods and the rate of perish-ability in case of organic goods. The first two factors considered, for which the time frame of the stationary observer is considered and the factors such as the risk of accidents and the rate of perish-ability of the goods are considered based on the time frame of the observer in transit's point of view. The reasons for such considerations and various assumptions on these concepts are dealt in this paper. The theorems that are formulated in this paper would provide the interstellar traders a basic

  16. Določanje konteksta okolja s pomočjo tehnologij iBeacon in Eddystone

    OpenAIRE

    2016-01-01

    V diplomskem delu se poglobimo v delovanje iBeacon in Eddystone tehnologije, ki temelji na Nizkoenergetskem Bluetoothu. Primerjamo njune prednosti in slabosti ter analiziramo varnostne ranljivosti tehnologije. Raziščemo tudi koncept Fizični splet, v sklopu katerega z Beacon oddajniki oddajamo URL naslove s predmetov v bližnje okolje. Prepoznamo in naštejemo priložnosti za integracijo Beacon oddajnikov v praktične in tržne rešitve. V praktičnem delu se posvetimo načrtovanju uporabniškga vm...

  17. Supplementary Material for: BEACON: automated tool for Bacterial GEnome Annotation ComparisON

    KAUST Repository

    Kalkatawi, Manal Matoq Saeed

    2015-01-01

    Abstract Background Genome annotation is one way of summarizing the existing knowledge about genomic characteristics of an organism. There has been an increased interest during the last several decades in computer-based structural and functional genome annotation. Many methods for this purpose have been developed for eukaryotes and prokaryotes. Our study focuses on comparison of functional annotations of prokaryotic genomes. To the best of our knowledge there is no fully automated system for detailed comparison of functional genome annotations generated by different annotation methods (AMs). Results The presence of many AMs and development of new ones introduce needs to: a/ compare different annotations for a single genome, and b/ generate annotation by combining individual ones. To address these issues we developed an Automated Tool for Bacterial GEnome Annotation ComparisON (BEACON) that benefits both AM developers and annotation analysers. BEACON provides detailed comparison of gene function annotations of prokaryotic genomes obtained by different AMs and generates extended annotations through combination of individual ones. For the illustration of BEACONâ s utility, we provide a comparison analysis of multiple different annotations generated for four genomes and show on these examples that the extended annotation can increase the number of genes annotated by putative functions up to 27 %, while the number of genes without any function assignment is reduced. Conclusions We developed BEACON, a fast tool for an automated and a systematic comparison of different annotations of single genomes. The extended annotation assigns putative functions to many genes with unknown functions. BEACON is available under GNU General Public License version 3.0 and is accessible at: http://www.cbrc.kaust.edu.sa/BEACON/ .

  18. Linear molecular beacons for highly sensitive bioanalysis based on cyclic Exo III enzymatic amplification.

    Science.gov (United States)

    Yang, Chaoyong James; Cui, Liang; Huang, Jiahao; Yan, Ling; Lin, Xiaoyan; Wang, Chunming; Zhang, Wei Yun; Kang, Huaizhi

    2011-09-15

    Sensitive analysis or monitoring of biomolecules and small molecules is very important for many biological researches, clinical diagnosis and forensic investigations. As a sequence-independent exonuclease, Exonuclease III (Exo III) has been widely used for amplified detection of proteins and nucleic acids where displacing probes or molecular beacons are used as the signaling probes. However, displacing probes suffer slow hybridization rate and high background signal and molecular beacons are difficult to design and prone to undesired nonspecific interactions. Herein, we report a new type of probes called linear molecular beacons (LMBs) for use in Exo III amplification assays to improve hybridization kinetics and reduce background noises. LMBs are linear oligonucleotide probes with a fluorophore and quencher attached to 3' terminal and penultimate nucleotides, respectively. Compared to conventional molecular beacons and displacing probes, LMBs are easy to design and synthesize. More importantly, LMBs have a much lower background noise and allow faster reaction rates. Using LMBs in cyclic Exo III amplification assay, ultrasensitive nucleic acid detection methods were developed with a detection limit of less than 120fM, which is 2 orders of magnitude lower than that of conventional molecular beacons or displacing probes-based Exo III amplification assays. Furthermore, LMBs can be extended as universal probes for detection of non-nucleic acid molecules such as cocaine with high sensitivity. These results demonstrate that the combination of Exo III amplification and LMB signaling provides a general method for ultrasensitive and selective detection of a wide range of targets. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Dual Functional Roles of Molecular Beacon as a MicroRNA Detector and Inhibitor.

    Science.gov (United States)

    Li, Wai Ming; Chan, Ching-Man; Miller, Andrew L; Lee, Chow H

    2017-03-03

    MicroRNAs are essential in many cellular processes. The ability to detect microRNAs is important for understanding its function and biogenesis. This study is aimed at using a molecular beacon to detect miR-430 in developing zebrafish embryos as a proof of principle. miR-430 is crucial for the clearance of maternal mRNA during maternal zygotic transition in embryonic development. Despite its known function, the temporal and spatial expression of miR-430 remains unclear. We used various imaging techniques, including laser scanning confocal microscopy, spinning disk, and lightsheet microscopy, to study the localization of miR-430 and any developmental defects possibly caused by the molecular beacon. Our results show that miR-430 is expressed early in development and is localized in distinct cytoplasmic granules where its target mRNA can be detected. We also show that the designed molecular beacon can inhibit the function of miR-430 and cause developmental defect in the brain, notochord, heart, and kidney, depending on the delivery site within the embryo, suggesting that miR-430 plays a diverse role in embryonic morphogenesis. When compared with morpholino, molecular beacon is 2 orders of magnitude more potent in inhibiting miR-430. Thus, our results reveal that in addition to being used as a valuable tool for the detection of microRNAs in vivo, molecular beacons can also be employed to inhibit microRNAs in a specific manner. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Double-hairpin molecular-beacon-based amplification detection for gene diagnosis linked to cancer.

    Science.gov (United States)

    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.

  1. Analysis of "Midnight" Tracks in the Stardust Interstellar Dust Collector: Possible Discovery of a Contemporary Interstellar Dust Grain

    Science.gov (United States)

    Westphal, A. J.; Allen, C.; Bajit, S.; Bastien, R.; Bechtel, H.; Bleuet, P.; Borg, J.; Brenker, F.; Bridges, J.; Brownlee, D. E.; Burchell, M.; Burghammer, M.; Butterworth, A. L.; Cloetens, P.; Cody, G.; Ferrior, T.; Floss, C.; Flynn, G. J.; Frank, D.; Gainsforth, Z.; Grun, E.; Hoppe, P.; Hudson, B.; Kearsley, A.; Lai, B.

    2010-01-01

    In January 2006, the Stardust sample return capsule returned to Earth bearing the first solid samples from a primitive solar system body, Comet 81P/Wild2, and a collector dedicated to the capture and return of contemporary interstellar dust. Both collectors were approximately 0.1m(exp 2) in area and were composed of aerogel tiles (85% of the collecting area) and aluminum foils. The Stardust Interstellar Dust Collector (SIDC) was exposed to the interstellar dust stream for a total exposure factor of 20 m(exp 2) day. The Stardust Interstellar Preliminary Examination (ISPE) is a three-year effort to characterize the collection using nondestructive techniques.

  2. Solar lens mission concept for interstellar exploration

    Science.gov (United States)

    Brashears, Travis; Lubin, Philip; Turyshev, Slava; Shao, Michael; Zhang, Qicheng

    2015-09-01

    The long standing approach to space travel has been to incorporate massive on-board electronics, probes and propellants to achieve space exploration. This approach has led to many great achievements in science, but will never help to explore the interstellar medium. Fortunately, a paradigm shift is upon us in how a spacecraft is constructed and propelled. This paper describes a mission concept to get to our Sun's Gravity Lens at 550AU in less than 10 years. It will be done by using DE-STAR, a scalable solar-powered phased-array laser in Earth Orbit, as a directed energy photon drive of low-mass wafersats. [1] [2] [3] [4] [5] With recent technologies a complete mission can be placed on a wafer including, power from an embedded radio nuclear thermal generator (RTG), PV, laser communications, imaging, photon thrusters for attitude control and other sensors. As one example, a futuristic 200 MW laser array consisting of 1 - 10 kw meter scale sub elements with a 100m baseline can propel a 10 gram wafer scale spacecraft with a 3m laser sail to 60AU/Year. Directed energy propulsion of low-mass spacecraft gives us an opportunity to capture images of Alpha Centauri and its planets, detailed imaging of the cosmic microwave background, set up interstellar communications by using gravity lenses around nearby stars to boost signals from interstellar probes, and much more. This system offers a very large range of missions allowing hundreds of wafer scale payload launches per day to reach this cosmological data reservoir. Directed Energy Propulsion is the only current technology that can provide a near-term path to utilize our Sun's Gravity Lens.

  3. Magnetic Fields in the Interstellar Medium

    Science.gov (United States)

    Clark, Susan

    2017-01-01

    The Milky Way is magnetized. Invisible magnetic fields thread the Galaxy on all scales and play a vital but still poorly understood role in regulating flows of gas in the interstellar medium and the formation of stars. I will present highlights from my thesis work on magnetic fields in the diffuse interstellar gas and in accretion disks. At high Galactic latitudes, diffuse neutral hydrogen is organized into an intricate network of slender linear features. I will show that these neutral hydrogen “fibers” are extremely well aligned with the ambient magnetic field as traced by both starlight polarization (Clark et al. 2014) and Planck 353 GHz polarized dust emission (Clark et al. 2015). The structure of the neutral interstellar medium is more tightly coupled to the magnetic field than previously known. Because the orientation of neutral hydrogen is an independent predictor of the local dust polarization angle, our work provides a new tool in the search for inflationary gravitational wave B-mode polarization in the cosmic microwave background, which is currently limited by dust foreground contamination. Magnetic fields also drive accretion in astrophysical disks via the magnetorotational instability (MRI). I analytically derive the behavior of this instability in the weakly nonlinear regime and show that the saturated state of the instability depends on the geometry of the background magnetic field. The analytical model describes the behavior of the MRI in a Taylor-Couette flow, a set-up used by experimentalists in the ongoing quest to observe MRI in the laboratory (Clark & Oishi 2016a, 2016b).

  4. Improving the detectability of oxygen saturation level targets for preterm neonates: A laboratory test of tremolo and beacon sonifications.

    Science.gov (United States)

    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.

  5. Interstellar extinction by fractal polycrystalline graphite clusters?

    CERN Document Server

    Andersen, A C; Pustovit, V N; Niklasson, G A

    2001-01-01

    Certain dust particles in space are expected to appear as clusters of individual grains. The morphology of these clusters could be fractal or compact. To determine how these structural features would affect the interpretation of the observed interstellar extinction peak at $\\sim 4.6~\\mu$m, we have calculated the extinction by compact and fractal polycrystalline graphite clusters consisting of touching identical spheres. We compare three general methods for computing the extinction of the clusters, namely, a rigorous solution and two different discrete-dipole approximation methods.

  6. Diffuse Interstellar Bands and Their Families

    CERN Document Server

    Wszolek, B

    2006-01-01

    Diffuse interstellar bands (DIBs) still await an explanation. One expects that some progress in this field will be possible when all the known DIBs are divided into families in such a way that only one carrier is responsible for all bands belonging to the given family. Analysing high resolution optical spectra of reddened stars we try to find out spectroscopic families for two prominent DIBs, at 5780 and 5797 angstroms. Among the DIBs, observed in the spectral range from 5590 to 6830 angstroms, we have found 8 candidates to belong to 5780 spectroscopic family and the other 12 DIBs candidating to family of 5797 structure.

  7. The 2014 KIDA network for interstellar chemistry

    CERN Document Server

    Wakelam, V; Herbst, E; Pavone, B; Bergeat, A; Béroff, K; Chabot, M; Faure, A; Galli, D; Geppert, W D; Gerlich, D; Gratier, P; Harada, N; Hickson, K M; Honvault, P; Klippenstein, S J; Picard, S D Le; Nyman, G; Ruaud, M; Schlemmer, S; Sims, I R; Talbi, D; Tennyson, J; Wester, R

    2015-01-01

    Chemical models used to study the chemical composition of the gas and the ices in the interstellar medium are based on a network of chemical reactions and associated rate coefficients. These reactions and rate coefficients are partially compiled from data in the literature, when available. We present in this paper kida.uva.2014, a new updated version of the kida.uva public gas-phase network first released in 2012. In addition to a description of the many specific updates, we illustrate changes in the predicted abundances of molecules for cold dense cloud conditions as compared with the results of the previous version of our network, kida.uva.2011.

  8. Formation of Interstellar OH and CH

    Science.gov (United States)

    Kwak, Kyujin; Yoon, Jeongkwan; Hong, Seungyeong

    2017-01-01

    From the absorption spectra of bright UV-emitting stars, column densities of interstellar OH (3078 and 3082 Å) and CH (3886 and 3890 Å) have been measured simultaneously along about 20 sightlines. In order to understand the physical and chemical environments in which these two molecules exist, we perform numerical simulations by using Astrochem, a publically available astrochemical reaction code. We investigate the effect of cosmic ray, grain, environmental photon, and initial composition on the formation of these two molecules. We also compare our simulated results with observations of molecule-forming objects such as supernova remnants, molecular clouds, and evolved stars along the observed sightlines.

  9. Can spores survive in interstellar space?

    Science.gov (United States)

    Weber, P.; Greenberg, J. M.

    1985-01-01

    Experimental evidence is presented for the effects of very low temperature and UV radiation, characteristic of the interstellar medium, on the survival of bacteria. In the most general space environment, 10 percent survival times are only of the order of hundreds of years, too short for panspermia to work. In a substantial fraction of space within dark clouds, however, it is shown that, even with conservative figures, survival times as long as millions to tens of millions of years are attainable. In such conditions, clouds could transport organisms from one solar system to another in times significantly shorter than the mean survival time. This occurs with significant probability.

  10. Ambient Interstellar Pressure and Superbubble Evolution

    CERN Document Server

    Oey, M S

    2004-01-01

    High ambient interstellar pressure is suggested as a possible factor to explain the ubiquitous observed growth-rate discrepancy for supernova-driven superbubbles and stellar wind bubbles. Pressures of P/k ~ 1e5 cm-3 K are plausible for regions with high star formation rates, and these values are intermediate between the estimated Galactic mid-plane pressure and those observed in starburst galaxies. High-pressure components also are commonly seen in Galactic ISM localizations. We demonstrate the sensitivity of shell growth to the ambient pressure, and suggest that superbubbles ultimately might serve as ISM barometers.

  11. Interstellar nomads: The problem of detecting comets

    Science.gov (United States)

    Jones, Eric M.; Newman, William I.; Campbell, Donald B.

    1993-01-01

    This paper shows that, using only a modest extrapolation of current phased-array radar and massively parallel processor computer technologies, radar transmitter in the outer solar system or in interstellar space could be used to detect comets passing within 1 or 2 AU of the transmitter. It discusses how this potential development could be instrumental to the colonisation of the outer solar system and beyond. This development is germane to contemporary investigations of the population of the Oort cloud as well as to the Search for Extraterrestrial Intelligence (SETI) question.

  12. LOCAL INTERSTELLAR MAGNETIC FIELD DETERMINED FROM THE INTERSTELLAR BOUNDARY EXPLORER RIBBON

    Energy Technology Data Exchange (ETDEWEB)

    Zirnstein, E. J.; Livadiotis, G.; McComas, D. J. [Southwest Research Institute, San Antonio, TX 78228 (United States); Heerikhuisen, J.; Pogorelov, N. V. [Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Funsten, H. O., E-mail: ezirnstein@swri.edu [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2016-02-10

    The solar wind emanating from the Sun interacts with the local interstellar medium (LISM), forming the heliosphere. Hydrogen energetic neutral atoms (ENAs) produced by the solar-interstellar interaction carry important information about plasma properties from the boundaries of the heliosphere, and are currently being measured by NASA's Interstellar Boundary Explorer (IBEX). IBEX observations show the existence of a “ribbon” of intense ENA emission projecting a circle on the celestial sphere that is centered near the local interstellar magnetic field (ISMF) vector. Here we show that the source of the IBEX ribbon as a function of ENA energy outside the heliosphere, uniquely coupled to the draping of the ISMF around the heliopause, can be used to precisely determine the magnitude (2.93 ± 0.08 μG) and direction (227.°28 ± 0.°69, 34.°62 ± 0.°45 in ecliptic longitude and latitude) of the pristine ISMF far (∼1000 AU) from the Sun. We find that the ISMF vector is offset from the ribbon center by ∼8.°3 toward the direction of motion of the heliosphere through the LISM, and their vectors form a plane that is consistent with the direction of deflected interstellar neutral hydrogen, thought to be controlled by the ISMF. Our results yield draped ISMF properties close to that observed by Voyager 1, the only spacecraft to directly measure the ISMF close to the heliosphere, and give predictions of the pristine ISMF that Voyager 1 has yet to sample.

  13. Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

    Science.gov (United States)

    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.

  14. The shape and composition of interstellar silicate grains

    NARCIS (Netherlands)

    Min, M.; Waters, L.B.F.M.; de Koter, A.; Hovenier, J.W.; Keller, L.P.; Markwick-Kemper, F.

    2007-01-01

    We investigate the composition and shape distribution of silicate dust grains in the interstellar medium. The effects of the amount of magnesium and iron in the silicate lattice are studied in detail. We fit the spectral shape of the interstellar 10 mu m extinction feature as observed towards the ga

  15. Interstellar gas, dust and diffuse bands in the SMC

    NARCIS (Netherlands)

    Cox, N.L.J.; Cordiner, M.A.; Ehrenfreund, P.; Kaper, L.; Sarre, P.J.; Foing, B.H.; Spaans, M.; Cami, J.; Sofia, U.J.; Clayton, G.C.; Gordon, K.D.; Salama, F.

    2007-01-01

    Aims.In order to gain new insight into the unidentified identity of the diffuse interstellar band (DIB) carriers, this paper describes research into possible links between the shape of the interstellar extinction curve (including the 2175 Å bump and far-UV rise), the presence or absence of DIBs, and

  16. The shape and composition of interstellar silicate grains

    NARCIS (Netherlands)

    Min, M.; Waters, L.B.F.M.; de Koter, A.; Hovenier, J.W.; Keller, L.P.; Markwick-Kemper, F.

    2007-01-01

    We investigate the composition and shape distribution of silicate dust grains in the interstellar medium. The effects of the amount of magnesium and iron in the silicate lattice are studied in detail. We fit the spectral shape of the interstellar 10 mu m extinction feature as observed towards the

  17. Dual hairpin-like molecular beacon based on coralyne-adenosine interaction for sensing melamine in dairy products.

    Science.gov (United States)

    Wang, Guangfeng; Zhu, Yanhong; Chen, Ling; Zhang, Xiaojun

    2014-11-01

    This study presents a novel dual hairpin-like molecular beacon (MB) for the selective and sensitive detection of melamine (MA) based on the conjugation of MA and thymine. In this protocol, the coordination between coralyne and adenosine (A) leaded a dual hairpin-like MB and the fluorophore-quencher pair is close proximity resulting in the fluorescence quenching. With the addition of MA, it conjugated with thymine in the loop part of dual hairpin-like MB by triple H-bonds, triggering the dissociation of the dual hairpin-like MB. The resulting spatial separation of the fluorophore from quencher induced the enhancement in fluorescence emission. Under the optimized conditions, the sensor exhibited a wide linear range of 8×10(-9)-1.6×10(-5) M (R(2)=0.9969) towards MA, with a low detection limit of 5 nM, approximately 4000 times lower than the Drug Administration and the US Food estimated MA safety limit. The real milk samples were also investigated with a satisfying result.

  18. Editorial: Interstellar Boundary Explorer (IBEX): Direct Sampling of the Interstellar Medium

    Science.gov (United States)

    McComas, D. J.

    2012-02-01

    This special supplement issue of the Astrophysical Journal comprises six coordinated papers that provide the first detailed analyses of the direct sampling of interstellar neutral atoms by the Interstellar Boundary Explorer (IBEX). Interstellar atoms are the detritus of older stars—their stellar winds, novae, and supernovae—spread across the galaxy, which fill the vast interstellar space between the stars. The very local interstellar medium around the Sun is filled with both ionized and neutral atoms with approximately equal numbers, and occasional ionization, charge exchange, and recombination makes them a single interacting material over large distances. IBEX (McComas et al. 2009a) is a NASA Small Explorer mission with the sole, focused science objective to discover the global interaction between the solar wind and the interstellar medium; this objective has primarily been achieved by taking the first global energetic neutral atom (ENA) images, which provide detailed ENA fluxes and energy spectra over all look directions in space. IBEX was launched 2008 October 19 and subsequently maneuvered into a high-altitude, highly elliptical (~15,000 × 300,000 km), roughly week-long orbit. The payload comprises two very high sensitivity, single-pixel ENA cameras: IBEX-Hi (Funsten et al. 2009a), which measures ENAs from ~300 eV to 6 keV, and IBEX-Lo (Fuselier et al. 2009a), which measures ENAs from ~10 eV to 2 keV. The initial IBEX ENA results were published together in a special issue of Science magazine (McComas et al. 2009b; Funsten et al. 2009b; Fuselier et al. 2009b; Schwadron et al. 2009). Since then there have been numerous additional studies of the IBEX ENA observations of the heliosphere, as well as ENAs from the Moon and Earth's magnetosphere (see recent review by McComas et al. 2011 and references therein). Prior to IBEX, the only interstellar neutral atoms to be directly sampled were He, observed by the Ulysses spacecraft a decade ago (Witte et al. 1996

  19. Beacons and surface features differentially influence human reliance on global and local geometric cues when reorienting in a virtual environment.

    Science.gov (United States)

    Bodily, Kent D; Kilday, Zachary A; Eastman, Caroline K; Gaskin, Katherine A; Graves, April A; Roberts, Jonathan E; Sturz, Bradley R

    2013-02-01

    In the reorientation literature, non-geometric cues include discrete objects (e.g., beacons) and surface-based features (e.g., colors, textures, and odors). To date, these types of non-geometric cues have been considered functionally similar, and it remains unknown whether beacons and surface features differentially influence the extent to which organisms reorient via global and local geometric cues. In the present experiment, we trained human participants to approach a location in a trapezoid-shaped enclosure uniquely specified by global and local geometric cues. We explored the role of beacons on the use of geometric cues by training participants in the presence or absence of uniquely-colored beacons. We explored the role of surface features on the use of geometric cues by recoloring two adjacent walls at the correct location and/or adding a line on the floor which corresponded to the major principal axis of the enclosure. All groups were then tested in novel-shaped enclosures in the absence of unique beacons and surface features to assess the relative use of global and local geometric cues. Results suggested that beacons facilitated the use of global geometric cues, whereas surface features either facilitated or hindered the use of geometric cues, depending on the feature. Published by Elsevier B.V.

  20. Cleavable DNA-protein hybrid molecular beacon: A novel efficient signal translator for sensitive fluorescence anisotropy bioassay.

    Science.gov (United States)

    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. Proceedings of the Symposium of the COSPAR Satellite Beacon Group on the Geophysical Use of Satellite Beacon Observations Held at Boston University on 1- 4 June 1976

    Science.gov (United States)

    1976-06-04

    the value of To. and t at the previous step. mLiz0 m EUNO+ONN ISPEON.TR F IATMSPHRE -I, IEUATONS TOTOiO ZTO PLSMi,,o. ~~O Wi.. AND, ,~ MODELO N , N...sophisti- cated calculations. The main features AiplieFiore Componentar th() Modelo in Figure 8 are the following: (a) the XSlow FioreC o n initial rapid...satellite 695 I.- ’I1 I VG.K. Hartmann 1969 Explorer 22 (con’d)J. Atinos . Terr. Phys. 31, (cont’d)663-669 Y.V. Somayajula 1976 Satellite radio beacon Tuhi

  2. Graphene Solar Photon Sails and Interstellar Arks

    Science.gov (United States)

    Matloff, G. L.

    2014-06-01

    A review of conceptual interstellar generation ships is followed by a presentation of optical and thermal properties of graphene and a discussion of kinematics/thermal-aspects of the solar-acceleration phase of a starship propelled by a graphene hollowbody solar-photon sail. The spacecraft departs from an initially parabolic solar orbit and the sail is oriented normal to the Sun during solar-acceleration. Perihelion is constrained to 0.1 AU because humans can tolerate ~3g for several hours without lasting effects. The 5 × 106 kg payload mass and 9.16 × 106 kg sail mass are applied as cosmic-ray shielding for the ship's 20-50 person population during the ~1,400-year cruise phase. Artificial gravity, the Coriolis Effect, closed-environment agriculture, illumination, on-board energy requirements, thermal dissipation, and hygiene/recreation are considered in a discussion of habitat design. Many concepts for mid-course trajectory correction are discussed including a new one that expels mass collected by a Cassenti toroidal ion scoop in a direction normal to the ship's trajectory. Although acceleration is affected by the unfurled sail, other options are discussed, as is the problem of protection from interstellar-dust erosion. As well as presenting the total mass budget, the conclusion reviews published variations and modifications on the generation-ship theme.

  3. The Ionization of Nearby Interstellar Gas

    CERN Document Server

    Slavin, J D; Slavin, Jonathan D.; Frisch, Priscilla C.

    2002-01-01

    We present new calculations of the photoionization of interstellar matter within ~5 pc of the Sun (which we refer to as the Local Cloud Complex or LCC) by directly observed radiation sources including nearby hot stars and the diffuse emission of the Soft X-ray Background (SXRB). In addition, we model the important, unobserved EUV emission both from the hot gas responsible for the SXRB and from a possible evaporative boundary between the LCC and the hot gas. We carry out radiative transfer calculations and show that these radiation sources can provide the ionization and heating of the cloud required to match a variety of observations. The ionization predicted in our models shows good agreement with pickup ion results, interstellar absorption line data towards epsilon CMa, and EUV opacity measurements of nearby white dwarf stars. Including the radiation from the conductive boundary improves agreement with data on the temperature and electron density in the cloud. The presence of dust in the cloud, or at least d...

  4. Galactic civilizations - Population dynamics and interstellar diffusion

    Science.gov (United States)

    Newman, W. I.; Sagan, C.

    1981-01-01

    A model is developed of the interstellar diffusion of galactic civilizations which takes into account the population dynamics of such civilizations. The problem is formulated in terms of potential theory, with a family of nonlinear partial differential and difference equations specifying population growth and diffusion for an organism with advantageous genes that undergoes random dispersal while increasing in population locally, and a population at zero population growth. In the case of nonlinear diffusion with growth and saturation, it is found that the colonization wavefront from the nearest independently arisen galactic civilization can have reached the earth only if its lifetime exceeds 2.6 million years, or 20 million years if discretization can be neglected. For zero population growth, the corresponding lifetime is 13 billion years. It is concluded that the earth is uncolonized not because interstellar spacefaring civilizations are rare, but because there are too many worlds to be colonized in the plausible colonization lifetime of nearby civilizations, and that there exist no very old galactic civilizations with a consistent policy of the conquest of inhabited worlds.

  5. Temperature fluctuations of interstellar dust grains

    CERN Document Server

    Horn, Kobi; Biham, Ofer

    2007-01-01

    The temperatures of interstellar dust grains are analyzed using stochastic simulations, taking into account the grain composition and size and the discreteness of the photon flux. [...] The distribution of grain temperatures is calculated for a broad range of grain sizes and for different intensities of the interstellar radiation field, relevant to diffuse clouds and to PDRs. The dependence of the average grain temperature on its size is shown for different irradiation intensities. It is found that the average temperatures of grains with radii smaller than about 0.02 $\\mu$m are reduced due to the fluctuations. The average temperatures of grains of radii larger than about 0.35 $\\mu$m are also slightly reduced due to their more efficient emission of infrared radiation, particularly when exposed to high irradiation intensities. The average temperatures of silicate and carbonaceous grains are found to depend on the radiation field intensity X_MMP according to ~X_MMP^gamma, where the exponent gamma depends on the...

  6. Interstellar Clouds Near the Sun, III

    Science.gov (United States)

    Frisch, Priscilla C.

    We propose to continue a study of interstellar sight-lines with low total column densities in order to determine the nature (temperature, density, fractional ionization) of the low density gas near the Sun and within the interior of the local superbubble. IUE data, combined with previous Copernicus observations, can be used to delimit the filling factor of nearby low density warm gas, and by default restrict the filling factor of 10^6 K plasma. In the proposed program, observations of MgI and ZnII(and in one region CIV) are combined with cloud maps and ground-based NaI observations (from a separate program) to restrict gas temperature, spatial and electron densities. The Welty et al. (1986) technique for removing fixed pattern noise through observations of a template star (used to flat-field the target stars on a pixel-by-pixel basis) is used to enable 3sigma absorption line detections at the 6-9 mA level, depending on the number of exposures involved. The ultimate goal of both the IUE and ground-based program is to map out the local interstellar medium. Apart from the intrinsic interest of this problem, it will help define regions where ultraviolet sources can be observed with FUSE/Lyman at lambda<912 A.

  7. Interstellar sulfur isotopes and stellar oxygen burning

    CERN Document Server

    Chin, Y N; Whiteoak, J B; Langer, N; Churchwell, E B; Chin, Y N

    1995-01-01

    A 12C32S, 13C32S, 12C34S, and 12C33S J = 2 - 1 line survey has been made to study interstellar 32S/34S and 34S/33S ratios from the galactic disk. The four CS isotopomers were detected in 20 star forming regions with galactocentric distances between 3 and 9 kpc. From a comparison of line velocities, the C33S J = 2 - 1 rest frequency is about 250 kHz below the value given in the Lovas (1992) catalog. Taking 12C/13C ratios from Wilson & Rood (1994) and assuming equal 12C32S and 13C32S excitation temperatures and beam filling factors, 12C32S opacities are in the range 3 to 15; average 32S/34S and 34S/33S isotope ratios are 24.4 +/- 5.0 and 6.27 +/- 1.01, respectively. While no systematic variation in the 34S/33S isotope ratio is found, the 32S/34S ratio increases with galactocentric distance when accounting for the 12C/13C gradient of the galactic disk. A fit to the unweighted data yields 32S/34S = 3.3 +/- 0.5 (dGC/kpc) + 4.1 +/- 3.1 with a correlation coefficient of 0.84. Since the interstellar sulfur (S) is...

  8. Prospects for the Detection of Interstellar Cyanovinylidene

    Science.gov (United States)

    Kołos, Robert; Gronowski, Marcin; Dobrowolski, Jan Cz.

    2009-08-01

    Prospects for the presence and detection of interstellar cyanovinylidene, CC(H)CN, a Y-shaped isomer of cyanoacetylene, are discussed. It is proposed that CC(H)CN can arise in interstellar clouds as one of the HC3NH+ + e - dissociative recombination products, by rearrangements of the neutral chain radical HC3NH into branched species HCCC(H)N, CC(H)C(H)N, and/or HCC(H)CN, and by the subsequent elimination of a hydrogen atom. It is deduced that the abundance of cyanovinylidene in molecular clouds should be confined between the abundances of its chain isomers HNCCC and HCNCC. Quantum chemical predictions regarding cyanovinylidene geometry, ground-state rotational constants, centrifugal distortion constants, spin-orbit coupling, IR absorption spectroscopy, and electric dipole moment are given. The spectroscopically observed molecules formyl cyanide, NC2(H)O, and propynal, HC3(H)O, with structures qualitatively resembling cyanovinylidene, served to prove the adequacy of the calculational procedures employed.

  9. Facts and Artifacts in Interstellar Diamond Spectra

    Science.gov (United States)

    Mutschke, H.; Dorschner, J.; Henning, T.; Jager, C.; Ott, U.

    1995-12-01

    Absorption spectra of presolar diamonds extracted from the Murchison meteorite have been measured in the extended wavelength range 0.2--500 mu m in order to make available optical properties of this supposed component of interstellar carbon dust. In contrast to terrestrial natural and synthetic diamonds, spectra of the meteoritic diamonds show prominent bands in the middle-IR. In this Letter, experimental evidence is presented that the OH band at 3200 cm-1 and the CH bands in the 2800--3000 cm-1 range are not intrinsic features of the diamonds and that the band at 1100 cm-1 contains an artificial component due to the extraction procedure. In addition, in our spectra a conspicuous band at 120 cm-1 was found. If the intrinsic character of this band, which, up to now, is unidentified, is confirmed, it would offer a chance to observe interstellar diamonds, e.g., by the ISO satellite. We encourage laboratory astrophysicists and observers to study this promising possibility.

  10. A Search for Interstellar Monohydric Thiols

    Science.gov (United States)

    Gorai, Prasanta; Das, Ankan; Das, Amaresh; Sivaraman, Bhalamurugan; Etim, Emmanuel E.; Chakrabarti, Sandip K.

    2017-02-01

    It has been pointed out by various astronomers that a very interesting relationship exists between interstellar alcohols and the corresponding thiols (sulfur analog of alcohols) as far as the spectroscopic properties and chemical abundances are concerned. Monohydric alcohols such as methanol and ethanol are widely observed and 1-propanol was recently claimed to have been seen in Orion KL. Among the monohydric thiols, methanethiol (chemical analog of methanol) has been firmly detected in Orion KL and Sgr B2(N2) and ethanethiol (chemical analog of ethanol) has been observed in Sgr B2(N2), though the confirmation of this detection is yet to come. It is very likely that higher order thiols could be observed in these regions. In this paper, we study the formation of monohydric alcohols and their thiol analogs. Based on our quantum chemical calculation and chemical modeling, we find that the Tg conformer of 1-propanethiol is a good candidate of astronomical interest. We present various spectroscopically relevant parameters of this molecule to assist in its future detection in the interstellar medium.

  11. Elemental nitrogen partitioning in dense interstellar clouds

    CERN Document Server

    Daranlot, Julien; Bergeat, Astrid; Costes, Michel; Loison, Jean-Christophe; Wakelam, Valentine; Hickson, Kevin M

    2012-01-01

    Many chemical models of dense interstellar clouds predict that the majority of gas-phase elemental nitrogen should be present as N2, with an abundance approximately five orders of magnitude less than that of hydrogen. As a homonuclear diatomic molecule, N2 is difficult to detect spectroscopically through infrared or millimetre-wavelength transitions so its abundance is often inferred indirectly through its reaction product N2H+. Two main formation mechanisms each involving two radical-radical reactions are the source of N2 in such environments. Here we report measurements of the low temperature rate constants for one of these processes, the N + CN reaction down to 56 K. The effect of the measured rate constants for this reaction and those recently determined for two other reactions implicated in N2 formation are tested using a gas-grain model employing a critically evaluated chemical network. We show that the amount of interstellar nitrogen present as N2 depends on the competition between its gas-phase format...

  12. The Interstellar Production of Biologically Important Organics

    Science.gov (United States)

    Sandford, Scott A.; Bernstein, Max P.; Dworkin, Jason; Allamandola, Louis J.

    2000-01-01

    One of the primary tasks of the Astrochemistry Laboratory at Ames Research Center is to use laboratory simulations to study the chemical processes that occur in dense interstellar clouds. Since new stars are formed in these clouds, their materials may be responsible for the delivery of organics to new habitable planets and may play important roles in the origin of life. These clouds are extremely cold (less than 50 kelvin), and most of the volatiles in these clouds are condensed onto dust grains as thin ice mantles. These ices are exposed to cosmic rays and ultraviolet (UV) photons that break chemical bonds and result in the production of complex molecules when the ices are warmed (as they would be when incorporated into a star-forming region). Using cryovacuum systems and UV lamps, this study simulates the conditions of these clouds and studies the resulting chemistry. Some of the areas of progress made in 1999 are described below. It shows some of the types of molecules that may be formed in the interstellar medium. Laboratory simulations have already confirmed that many of these compounds are made under these conditions.

  13. Streaming of interstellar grains in the solar system

    Science.gov (United States)

    Gustafson, B. A. S.; Misconi, N. Y.

    1979-01-01

    Results of a theoretical study of the interactions between interstellar grains streaming through the solar system and the solar wind are presented. It is shown that although elongated core-mantle interstellar particles of a characteristic radius of about 0.12 microns are subject to a greater force due to radiation pressure than to gravitational attraction, they are still able to penetrate deep inside the solar system. Calculations of particle trajectories within the solar system indicate substantial effects of the solar activity cycle as reflected in the interplanetary magnetic field on the distribution of 0.12- and 0.0005-micron interstellar grains streaming through the solar system, leading to a 50-fold increase in interstellar grain densities 3 to 4 AU ahead of the sun during years 8 to 17 of the solar cycle. It is noted that during the Solar Polar Mission, concentrations are expected which will offer the opportunity of detecting interstellar grains in the solar system.

  14. Design of a K/Q-Band Beacon Receiver for the Alphasat TDP#5 Experiment

    Science.gov (United States)

    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.

  15. Evaluation design and technical assistance opportunities: early findings from the Beacon Community Program evaluation teams.

    Science.gov (United States)

    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.

  16. Nanosecond-level time synchronization of AERA using a beacon reference transmitter and commercial airplanes

    Directory of Open Access Journals (Sweden)

    Huege Tim

    2017-01-01

    Full Text Available Radio detection of cosmic-ray air showers requires time synchronization of detectors on a nanosecond level, especially for advanced reconstruction algorithms based on the wavefront curvature and for interferometric analysis approaches. At the Auger Engineering Radio Array, the distributed, autonomous detector stations are time-synchronized via the Global Positioning System which, however, does not provide sufficient timing accuracy. We thus employ a dedicated beacon reference transmitter to correct for eventby-event clock drifts in our offline data analysis. In an independent cross-check of this “beacon correction” using radio pulses emitted by commercial airplanes, we have shown that the combined timing accuracy of the two methods is better than 2 nanoseconds.

  17. Nanosecond-level time synchronization of AERA using a beacon reference transmitter and commercial airplanes

    Science.gov (United States)

    Huege, Tim

    2017-03-01

    Radio detection of cosmic-ray air showers requires time synchronization of detectors on a nanosecond level, especially for advanced reconstruction algorithms based on the wavefront curvature and for interferometric analysis approaches. At the Auger Engineering Radio Array, the distributed, autonomous detector stations are time-synchronized via the Global Positioning System which, however, does not provide sufficient timing accuracy. We thus employ a dedicated beacon reference transmitter to correct for eventby-event clock drifts in our offline data analysis. In an independent cross-check of this "beacon correction" using radio pulses emitted by commercial airplanes, we have shown that the combined timing accuracy of the two methods is better than 2 nanoseconds.

  18. Multi-beam laser beacon propagation over lunar distance: comparison of predictions and measurements

    Science.gov (United States)

    Biswas, A.; Piazzolla, S.

    2017-02-01

    A multi-beam beacon was transmitted from the Optical Communication Telescope Laboratory (OCTL) located at Table Mountain, CA to the Lunar Laser Space Terminal (LLST), on-board the Lunar Atmospheric Dust and Environment Explorer (LADEE) spacecraft, during NASA's recent Lunar Laser Communication Demonstration (LLCD). The laser beacon (1568+/-0.1 nm) was square wave modulated and sensed by a quadrant sensor on LLST. While link acquisition and tracking proceeded with the sensed signal, on-board processing extracted power incident on the quadrant sensor and telemetered it down over the optical downlink. Subsequently, post-processing of the codewords received at OCTL retrieved the power time series recorded at LLST. Analysis comparing measured and predicted mean irradiance delivered to LLST consistently agreed to within < 1 decibel (dB). Irradiance fluctuations detected at LLST were reconciled with an uplink wave-propagation simulation model using Kolmogorov phase screens.

  19. Performance evaluation of beacon enabled IEEE 802.15.4 under NS2

    CERN Document Server

    Charfi, Faiza

    2012-01-01

    The increasing demand for real-time applications has made the Quality of Service (Qos) support for wireless sensor networks (WSN) a fairly new research framework. In this paper, we propose an extended model of the Beacon enabled IEEE 802.15.4 including the Guaranteed Time Slot GTS allocation mechanism in the aim to analyze and evaluate network performances. Series of extensive simulations were performed to analyze the impact of the Beacon Order BO and the Superframe Order SO on the network performance based on commonly known metrics. In particular, we examine data packet delivery performance and the throughput for different duty cycle rates. Also, we analyze the impact of the number of nodes on collision probability. Thus, for high number of nodes, collision becomes higher and the reachability begins to decline slightly. We discuss and compare simulation results conducted under various parameter settings to the IEEE 802.11 network.

  20. Nanosecond-level time synchronization of AERA using a beacon reference transmitter and commercial airplanes

    CERN Document Server

    Huege, Tim

    2016-01-01

    Radio detection of cosmic-ray air showers requires time synchronization of detectors on a nanosecond level, especially for advanced reconstruction algorithms based on the wavefront curvature and for interferometric analysis approaches. At the Auger Engineering Radio Array, the distributed, autonomous detector stations are time-synchronized via the Global Positioning System which, however, does not provide sufficient timing accuracy. We thus employ a dedicated beacon reference transmitter to correct for event-by-event clock drifts in our offline data analysis. In an independent cross-check of this "beacon correction" using radio pulses emitted by commercial airplanes, we have shown that the combined timing accuracy of the two methods is better than 2 nanoseconds.

  1. Creation of a Library Tour Application for Mobile Equipment using iBeacon Technology

    Directory of Open Access Journals (Sweden)

    Jonathan Bradley

    2016-04-01

    Full Text Available We describe the design, development, and deployment of a library tour application utilizing Bluetooth Low Energy devices know as iBeacons. The tour application will serve as library orientation for incoming students. The students visit stations in the library with mobile equipment running a special tour app. When the app detects a beacon nearby, it automatically plays a video that describes the current location. After the tour, students are assessed according to the defined learning objectives. Special attention is given to issues encountered during development, deployment, content creation, and testing of this application that depend on functioning hardware, and the necessity of appointing a project manager to limit scope, define priorities, and create an actionable plan for the experiment.

  2. Method and apparatus for a multibeam beacon laser assembly for optical communications

    Science.gov (United States)

    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.

  3. Ultrasensitive monitoring of ribozyme cleavage product using molecular-beacon-ligation system

    Institute of Scientific and Technical Information of China (English)

    MENG XiangXian; TANG ZhiWen; WANG KeMin; TAN WeiHong; YANG XiaoHai; LI Jun; GUO QiuPing

    2007-01-01

    This paper reports a new approach to detect ribozyme cleavage product based on the molecular- beacon-ligation system. The molecular beacon, designed in such a way that one-half of its loop is complementary to ribozyme cleavage product, is used to monitor ligation process of RNA/DNA complex in a homogeneous solution and to convert directly cleavage product information into fluorescence signal. The method need not label ribozyme and ribozyme substrate, which is fast, simple and ultrasensitive for detection of cleavage product. Detection limit of the assay is 0.05 nmol/L. The cleavage product of hammerhead ribozyme against hepatitis C virus RNA (HCV-RNA) was detected perfectly based on this assay. Owing to its ultrasensitivity, excellent specificity, convenience and fidelity, this method might hold out great promise in ribozyme reaction and ribozyme gene therapy.

  4. BEACON FRAME MANIPULATION TO MITIGATE ROGUE ACCESS POINTS: CASE OF ANDROID SMARTPHONE ROGUE ACCESS POINTS

    Directory of Open Access Journals (Sweden)

    Thambo Nyathi

    2015-11-01

    Full Text Available The use of wireless devices to access corporate network resources is now part of the norm within corporate environments. When wireless users need to connect to a network they hardly question the source of their connectivity. Mobile phones, particularly smartphones allow users to access network resources. These harmless looking wireless devices can be a source of major threats if configured to be so. The Internet is awash with mobile apps capable of performing packet sniffing. These applications, coupled with the capability of the smartphone to be configured as an access point, can present a Smartphone Rogue Access Point. Access Points advertise their availability using what is called a beacon frame. This research paper proposes a solution which restructures this beacon frame to include an Authentic Access Point Value which can be used to defend against Rogue Access Points.

  5. A Telomerase-Specific Doxorubicin-Releasing Molecular Beacon for Cancer Theranostics.

    Science.gov (United States)

    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.

  6. Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

    Science.gov (United States)

    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.

  7. Performance Evaluation Of BEACON-ENABLED IEEE 802.15.4 Under NS2

    Directory of Open Access Journals (Sweden)

    Faiza Charfi

    2012-04-01

    Full Text Available The increasing demand for real-time applications has made the Quality of Service (Qos support for wireless sensor networks (WSN a fairly new research framework. In this paper, we propose an extended model of the Beacon enabled IEEE 802.15.4 including the Guaranteed Time Slot GTS allocation mechanism in the aim to analyze and evaluate network performances. Series of extensive simulations were performed to analyze the impact of the Beacon Order BO and the Superframe Order SO on the network performance based on commonly known metrics. In particular, we examine data packet delivery performance and the throughput for different duty cycle rates. Also, we analyze the impact of the number of nodes on collision probability. Thus, for high number of nodes, collision becomes higher and the reachability begins to decline slightly. We discuss and compare simulation results conducted under various parameter settings to the IEEE 802.11network.

  8. Topical MMP beacon enabled fluorescence-guided resection of oral carcinoma.

    Science.gov (United States)

    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 (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.

  9. Filtration of interstellar hydrogen in the two-shock heliospheric interface Inferences on the local interstellar electron density

    CERN Document Server

    Izmodenov, V V; Lallement, R; Glöckler, G; Baranov, V B; Malama, Y G

    1998-01-01

    The solar system is moving through the partially ionized local interstellar cloud (LIC). The ionized matter of the LIC interacts with the expanding solar wind forming the heliospheric interface. The neutral component (interstellar atoms) penetrates through the heliospheric interface into the heliosphere, where it is measured directly "in situ" as pick-up ions and neutral atoms (and as anomalous cosmic rays) or indirectly through resonant scattering of solar Ly-alpha. When crossing the heliospheric interface, interstellar atoms interact with the plasma component through charge exchange. This interaction leads to changes of both neutral gas and plasma properties. The heliospheric interface is also the source of radio emissions which have been detected by the Voyager since 1983. In this paper, we have used a kinetic model of the flow of the interstellar atoms with updated values of velocity, temperature, and density of the circumsolar interstellar hydrogen and calculated how all quantities which are directly ass...

  10. Photodynamic Molecular Beacons: An Image-Guided Therapeutic Approach to Breast Cancer Vertebral Metastases

    Science.gov (United States)

    2011-03-01

    which will restrict the drug and light doses that can be used safely. MMP PDT beacons potentially address this limitation. We have demonstrated the...Shao, R., Ji, X., Gelovani, J. G., and Li, C. (2007) A novel method for imaging in vivo degradation of poly(L-glutamic acid), a biodegradable drug ...Piwnica-Worms, D. (2003) Quantitative analysis of permeation peptide complexes labeled with Technetium-99m: chiral and sequence-specific effects on net cell

  11. Experimental Demonstration of Real Time Gradient Gain Correction for Sodium Beacon Laser Guide Star: Postprint

    Science.gov (United States)

    2010-06-01

    norma lized by itse lf at each frame. The blue and green curves are two identical Nu ll space runs, which start oul at Ihe bolt om, and end up...Simulator ( software package) • ATS - Atmospheric Turbulence Simulator (hardware on the table) • OM - Defonnable Mirror • LGS - Laser Guide Star...The.l:- {///{/ y- IVFS gaills are difJerelll. Figure 5 shows ACS software simulation data for a high resolution SH camera for sodium beacon LGS with

  12. Developing children's palliative care in Africa through beacon centres: lessons learnt.

    Science.gov (United States)

    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.

  13. Increased dose near the skin due to electromagnetic surface beacon transponder.

    Science.gov (United States)

    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.

  14. Cuba’s Education System: A Beacon of Light in Latin America Facing an Uncertain Future

    OpenAIRE

    Johnstone, Brian

    2008-01-01

    While the international community, through the United Nations Educational, Scientific and Cultural Organization (UNESCO), is promoting a global policy of Education for All (EFA), Cuba stands out as a beacon to other developing countries that have so far been unable to achieve their EFA goals. This paper presents a regional quantitative comparison of eleven Latin American and Caribbean countries—Argentina, Bolivia, Brazil, Chile, Colombia, Cuba, Honduras, Mexico, Paraguay, Dominican Republic, ...

  15. ENHANCED COMPOSITE APPROACH WITH MOBILE BEACON SHORTEST PATH TO SOLVE LOCALIZATION PROBLEM IN WIRELESS SENSOR NETWORK

    Directory of Open Access Journals (Sweden)

    Sunil Kumar,

    2010-12-01

    Full Text Available Wireless sensor network is tremendously being used in different environments to perform various monitoring task such as search, rescue, disaster relief, target tracking and a number of tasks in smart environment. In this paper a unique localization algorithm is proposed that gives the high accuracy in wireless sensor network. We propose amobile beacon algorithm and then merge it with DV- hop algorithm to introduce a unique approach which solves the localization problem in wireless sensor network.

  16. Trajectory optimization and applications using high performance solar sails

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The high performance solar sail can enable fast missions to the outer solar system and produce exotic non-Keplerian orbits.As there is no fuel consumption,mission trajectories for solar sail spacecraft are typically optimized with respect to flight time.Several investigations focused on interstellar probe missions have been made,including optimal methods and new objective functions. Two modes of interstellar mission trajectories,namely "direct flyby" and "angular momentum reversal trajectory",are compare...

  17. Magnetic resonance beacon to detect intracellular microRNA during neurogenesis.

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. In situ single step detection of exosome microRNA using molecular beacon.

    Science.gov (United States)

    Lee, Ji Hye; Kim, Jeong Ah; Kwon, Min Hee; Kang, Ji Yoon; Rhee, Won Jong

    2015-06-01

    In situ single step detection of microRNAs (miRNA) in a whole exosome has been developed as a novel diagnosis method that can be utilized for various diseases. Exosomes are small extracellular vesicles that contain biomarker miRNAs produced from their originating cells and are known to travel through the circulatory system. This makes exosomal miRNAs from the body fluids an attractive biomarker that can lead to a paradigm shift in the diagnosis of disease. However, current techniques, including real-time PCR analysis, are time-consuming and laborious, making them unsuitable for exosomal miRNA detection for diagnosis. Thus, the development of alternative methods is necessary. Herein, we have demonstrated that exosomal miRNAs can be detected directly using a nano-sized fluorescent oligonucleotide probe, molecular beacon. MiRNA-21 in exosomes from breast cancer cells were detected successfully by molecular beacons in a quantitative manner. Permeabilization by streptolysin O treatment further enhanced the delivery of molecular beacons into exosomes, giving significantly increased signals from target miRNAs. In addition, we selectively detected cancer cell-derived exosomal miRNA-21 among heterogeneous exosome mixtures and in human serum. The method developed in the article is simple, fast, and sensitive, so it will offer great opportunities for the high-throughput diagnosis and prognosis of diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Enhancement-Mode TACAN Beaconing Antenna%增强型塔康信标天线

    Institute of Scientific and Technical Information of China (English)

    史小鸣; 苟锋

    2015-01-01

    The operating range and measuring accuracy are directly influenced by TACAN beaconing antenna, currently TACAN beaconing antenna has the characters of modulation circuit loss and modulation pattern reduction and it may enlarge the transmitting power of ground equipment demand. A zero subsidence area exists within the covering range which is unable to measure. The two enhancement-mode TACAN beaconing antennas which use the receiving and sending beam separation theory are presented in this paper. They may effective improve and solve those problems.%塔康信标天线直接影响塔康系统的作用距离和测位精度.现有塔康信标天线存在调制电路损耗与调制方向图衰减等固有特性,造成地面设备需求的发射功率大,并且覆盖距离内往往存在无法测距的"零陷区".本文提出应用收、发波束分离原理的两种增强型塔康天线概念,可望有效改善或解决这些问题.

  20. A multistatic HF beacon network for ionospheric specification in the Peruvian sector

    Science.gov (United States)

    Hysell, D. L.; Milla, M. A.; Vierinen, J.

    2016-05-01

    A small network of HF beacon transmitters and receivers has been deployed in Peru for specifying the F region ionosphere in the sector. The effort is motivated by ionospheric disturbances associated with equatorial spread F (ESF) and specifically disturbances arising under inauspicious conditions for ESF as determined by numerical simulations. The beacons operate at dual frequencies (2.72 and 3.64 MHz). They are CW but incorporate pseudorandom noise (PRN) coding so that the group delays of the links can be measured. Other observables are power, Doppler shift, bearing, and polarization. A transmitter is currently deployed at Ancon (11°46'37''S, 77°09'1''W, 51 m above sea level (asl)), while receivers are at Jicamarca (11°57'5.8''S, 76°52'27''W, 510 m asl) and Huancayo (12°02'30''S, 75°19'15''W, 3315 m asl). An algorithm for inverting the beacon data combined with electron density profiles from Jicamarca is described. Data and representative solutions from an experimental campaign held in August 2015 are presented and evaluated.

  1. Interstellar Mapping and Acceleration Probe (IMAP)

    Science.gov (United States)

    Schwadron, N. A.; Opher, M.; Kasper, J.; Mewaldt, R.; Moebius, E.; Spence, H. E.; Zurbuchen, T. H.

    2016-11-01

    Our piece of cosmic real estate, the heliosphere, is the domain of all human existence - an astrophysical case history of the successful evolution of life in a habitable system. By exploring our global heliosphere and its myriad interactions, we develop key physical knowledge of the interstellar interactions that influence exoplanetary habitability as well as the distant history and destiny of our solar system and world. IBEX is the first mission to explore the global heliosphere and in concert with Voyager 1 and Voyager 2 is discovering a fundamentally new and uncharted physical domain of the outer heliosphere. In parallel, Cassini/INCA maps the global heliosphere at energies (˜5-55 keV) above those measured by IBEX. The enigmatic IBEX ribbon and the INCA belt were unanticipated discoveries demonstrating that much of what we know or think we understand about the outer heliosphere needs to be revised. This paper summarizes the next quantum leap enabled by IMAP that will open new windows on the frontier of Heliophysics at a time when the space environment is rapidly evolving. IMAP with 100 times the combined resolution and sensitivity of IBEX and INCA will discover the substructure of the IBEX ribbon and will reveal, with unprecedented resolution, global maps of our heliosphere. The remarkable synergy between IMAP, Voyager 1 and Voyager 2 will remain for at least the next decade as Voyager 1 pushes further into the interstellar domain and Voyager 2 moves through the heliosheath. Voyager 2 moves outward in the same region of sky covered by a portion of the IBEX ribbon. Voyager 2’s plasma measurements will create singular opportunities for discovery in the context of IMAP's global measurements. IMAP, like ACE before, will be a keystone of the Heliophysics System Observatory by providing comprehensive measurements of interstellar neutral atoms and pickup ions, the solar wind distribution, composition, and magnetic field, as well as suprathermal ion, energetic

  2. Diffuse interstellar bands as probes of small-scale interstellar structure

    CERN Document Server

    Smith, Keith T; Sarre, Peter J

    2013-01-01

    We present observations which probe the small-scale structure of the interstellar medium using diffuse interstellar bands (DIBs). Towards HD 168075/6 in the Eagle Nebula, significant differences in DIB absorption are found between the two lines of sight, which are separated by 0.25 pc, and {\\lambda}5797 exhibits a velocity shift. Similar data are presented for four stars in the {\\mu} Sgr system. We also present a search for variations in DIB absorption towards {\\kappa} Vel, where the atomic lines are known to vary on scales of ~10 AU. Observations separated by ~9 yr yielded no evidence for changes in DIB absorption strength over this scale, but do reveal an unusual DIB spectrum.

  3. Can Composite Fluffy Dust Particles Solve the Interstellar Carbon Crisis?

    CERN Document Server

    Dwek, E

    1997-01-01

    Interstellar dust models are facing a "carbon crisis", so called because recent observations suggest that the abundance of carbon available for dust in the interstellar medium is less than half of the amount required to be tied up in graphite grains in order to explain the interstellar extinction curve. This paper presents an detailed assessment of a newly-proposed dust model (Mathis 1996), in which the majority of the interstellar carbon is contained in composite and fluffy dust (CFD) grains. Per unit mass, these grains produce more UV extinction, and can therefore account for the interstellar extinction curve with about half the carbon required in traditional dust models. The results of our analysis show that the CFD model falls short in solving the carbon crisis, in providing a fit to the UV-optical interstellar extinction curve. It also predicts a far-infrared emissivity in excess of that observed with the COBE/DIRBE and FIRAS instruments from the diffuse interstellar medium. The failure of the new model ...

  4. The interstellar dust reservoir: SPICA's view on dust production and the interstellar medium in galaxies

    CERN Document Server

    Kemper, F; Jones, O C; Srinivasan, S

    2016-01-01

    Typical galaxies emit about one third of their energy in the infrared. The origin of this emission reprocessed starlight absorbed by interstellar dust grains and reradiated as thermal emission in the infrared. In particularly dusty galaxies, such as starburst galaxies, the fraction of energy emitted in the infrared can be as high as 90%. Dust emission is found to be an excellent tracer of the beginning and end stages of a star's life, where dust is being produced by post-main-sequence stars, subsequently added to the interstellar dust reservoir, and eventually being consumed by star and planet formation. This work reviews the current understanding of the size and properties of this interstellar dust reservoir, by using the Large Magellanic Cloud as an example, and what can be learned about the dust properties and star formation in galaxies from this dust reservoir, using SPICA, building on previous work performed with the Herschel and Spitzer Space Telescopes, as well as the Infrared Space Observatory.

  5. Comparisons of the Interstellar Magnetic Field Directions obtained from the IBEX Ribbon and Interstellar Polarizations

    CERN Document Server

    Frisch, Priscilla C; Berdyugin, Andrei; Funsten, Herbert O; Magalhaes, Mario; McComas, David J; Piirola, Vilppu; Schwadron, Nathan A; Slavin, Jonathan D; Wiktorowicz, Sloane J

    2010-01-01

    Variations in the spatial configuration of the interstellar magnetic field (ISMF) near the Sun can be constrained by comparing the ISMF direction at the heliosphere found from the Interstellar Boundary Explorer spacecraft (IBEX) observations of a 'Ribbon' of energetic neutral atoms (ENAs), with the ISMF direction derived from optical polarization data for stars within ~40 pc. Using interstellar polarization observations towards ~30 nearby stars within 90 deg of the heliosphere nose, we find that the best fits to the polarization position angles are obtained for a magnetic pole directed towards ecliptic coordinates of lambda, beta 263 deg, 37 deg (or galactic coordinates of L,B 38 deg, 23deg), with uncertainties of +/- 35 deg, based on the broad minimum of the best fits and the range of data quality. This magnetic pole is 33 deg from the magnetic pole that is defined by the center of the arc of the ENA Ribbon. The IBEX ENA ribbon is seen in sightlines that are perpendicular to the ISMF as it drapes over the he...

  6. The Centauri project: Manned interstellar travel

    Science.gov (United States)

    Ciesla, Thomas M.

    1990-01-01

    The development of antimatter engines for spacecraft propulsion will allow man to expand to the nearest stellar neighbors such as the Alpha Centuri system. Compared to chemically powered rockets like the Apollo mission class which would take 50,000 years to reach the Centauri system, antimatter propulsion would reduce one way trip time to 30 years or less. The challenges encountered by manned interstellar travel are formidable. The spacecraft must be a combination of sublight speed transportation system and a traveling microplanet serving an expanding population. As the population expands from the initial 100 people to approximately 300, the terraformed asteroid, enclosed by a man-made shell will allow for expansion over its surface in the fashion of a small terrestrial town. All aspects of human life - birth; death; physical, emotional, and educational needs; and government and law must be met by the structure, systems, and institutions on-board.

  7. Supernova Feedback and Multiphase Interstellar Medium

    Science.gov (United States)

    Li, Miao; Ostriker, Jeremiah P.; Cen, Renyue; Bryan, Greg; Naab, Thorsten

    2015-01-01

    Without feedback, galaxies in cosmological simulations fail to generate outflows and tend to be too massive and too centrally concentrated, in contrast to the prominent disks observed ubiquitously in our universe. The nature of supernova (SN) feedback remains, however, highly uncertain, and most galaxy simulations so far adopt ad hoc models. Here we perform parsec-resolution simulations of a patch of the interstellar medium (ISM), and show that the unresolved multiphase gas in cosmological simulations can greatly affect the SN feedback by allowing blastwaves to travel in-between the clouds. We also show how ISM clumping varies with the mean gas density and SN rate encountered in real galactic environments. We emphasize that the inhomogeneity of the ISM must be considered in coarse-resolution simulations. We discuss how the gas pressure maintained by SN explosions can help to launch the galactic winds, and compare our results with the sub-grid models adopted in current cosmological simulations.

  8. Ritual, meaningfulness, and interstellar message construction

    Science.gov (United States)

    Traphagan, John W.

    2010-10-01

    In this paper, I am interested in exploring the potential of ritual performance as a means of communication with ETI. I argue that the study of ritual and ritualized behavior, understood as a technique for representation of meaning and meaningfulness about the world, has potential to inform how scientists think about the construction and interpretation of interstellar messages. I do not suggest that ritual activities themselves provide more than limited potential for communication with ETI. However, the structural elements of ritual and the manner in which meaning is conveyed through the formality and repetition of ritual is at least to some extent decipherable cross-culturally and provides one way to think about how to express important aspects of humans and their cultures to ETI and to represent, if not specific meanings themselves, the fact that a message is meaningful.

  9. Supernova Feedback in an Inhomogeneous Interstellar Medium

    CERN Document Server

    Martizzi, Davide; Quataert, Eliot

    2014-01-01

    Supernova (SN) feedback is one of the key processes shaping the interstellar medium (ISM) of galaxies. SNe contribute to (and in some cases may dominate) driving turbulence in the ISM and accelerating galactic winds. Modern cosmological simulations have sufficient resolution to capture the main structures in the ISM of galaxies, but are typically still not capable of explicitly resolving all of the small-scale stellar feedback processes, including the expansion of supernova remnants (SNRs). We perform a series of controlled three-dimensional hydrodynamic (adaptive mesh refinement, AMR) simulations of single SNRs expanding in an inhomogeneous density field with statistics motivated by those of the turbulent ISM. We use these to quantify the momentum and thermal energy injection from SNe as a function of spatial scale and the density, metallicity, and structure of the ambient medium. Using these results, we develop an analytic sub-resolution model for SN feedback for use in galaxy formation simulations. We then...

  10. Interstellar Dust models towards some IUE stars

    CERN Document Server

    Katyal, Nisha; Vaidya, D B

    2013-01-01

    We study the extinction properties of the composite dust grains, consisting of host silicate spheroids and graphite as inclusions, using discrete dipole approximation (DDA). We calculate the extinction cross sections of the composite grains in the ultraviolet spectral region, 1200\\AA -3200\\AA and study the variation in extinction as a function of the volume fraction of the inclusions. We compare the model extinction curves with the observed interstellar extinction curves obtained from the data given by the International Ultraviolet Explorer (IUE) satellite. Our results for the composite grains show a distinct variation in the extinction efficiencies with the variation in the volume fraction of the inclusions. In particular, it is found that the wavelength of peak absorption at `2175\\AA' shifts towards the longer wavelength with the variation in the volume fraction of inclusions. We find that the composite grain models with the axial ratios viz. 1.33 and 2.0 fit the observed extinction reasonably well with a g...

  11. Modelling Study of Interstellar Ethanimine Isomers

    Science.gov (United States)

    Quan, Donghui; Herbst, Eric; Corby, Joanna F.; Durr, Allison; Hassel, George

    2016-06-01

    Ethanimine (CH3CHNH) , including both the E- and Z- isomers, were detected towards the star-forming region Sgr B2(N) using the GBT PRIMOS data (Loomis et al 2013), and were recently imaged by the ACTA (Corby et al. 2015). These aldimines can serve as precursors of biological molecules such as amino acids thus are considered prebiotic molecules in interstellar medium. In this study, we present chemical simulations of ethanimine with various physical conditions. From models for Sgr B2(N) and environs, calculated ethanimine abundances show reasonable agreement with observed values, while the translucent cloud models yield much lower abundances. These results agree with locations suggested by observations that ethanimine isomers were detected in the foreground of the shells of the hot core.

  12. Formation of Cyanoformaldehyde in the interstellar space

    CERN Document Server

    Das, Ankan; Chakrabarti, Sandip K; Saha, Rajdeep; Chakrabarti, Sonali

    2013-01-01

    Cyanoformaldehyde (HCOCN) molecule has recently been suspected towards the Sagittarius B2(N) by the Green Bank telescope, though a confirmation of this observation has not yet been made. In and around a star forming region, this molecule could be formed by the exothermic reaction between two abundant interstellar species, H$_2$CO and CN. Till date, the reaction rate coefficient for the formation of this molecule is unknown. Educated guesses were used to explain the abundance of this molecule by chemical modeling. In this paper, we carried out quantum chemical calculations to find out empirical rate coefficients for the formation of HCOCN and different chemical properties during the formation of HCOCN molecules. Though HCOCN is stable against unimolecular decomposition, this gas phase molecule could be destroyed by many other means, like: ion-molecular reactions or by the effect of cosmic rays. Ion-molecular reaction rates are computed by using the capture theories. We have also included the obtained rate coef...

  13. The kinetic chemistry of dense interstellar clouds

    Science.gov (United States)

    Graedel, T. E.; Langer, W. D.; Frerking, M. A.

    1982-01-01

    A model of the time-dependent chemistry of dense interstellar clouds is formulated to study the dominant chemical processes in carbon and oxygen isotope fractionation, the formation of nitrogen-containing molecules, and the evolution of product molecules as a function of cloud density and temperature. The abundances of the dominant isotopes of the carbon- and oxygen-bearing molecules are calculated. The chemical abundances are found to be quite sensitive to electron concentration since the electron concentration determines the ratio of H3(+) to He(+), and the electron density is strongly influenced by the metals abundance. For typical metal abundances and for H2 cloud density not less than 10,000 molecules/cu cm, nearly all carbon exists as CO at late cloud ages. At high cloud density, many aspects of the chemistry are strongly time dependent. Finally, model calculations agree well with abundances deduced from observations of molecular line emission in cold dense clouds.

  14. Calculating Cross Sections of Composite Interstellar Grains

    CERN Document Server

    Voshchinnikov, N V; Voshchinnikov, Nikolai V.; Mathis, John S.

    1999-01-01

    Interstellar grains may be composite collections of particles of distinct materials, including voids, agglomerated together. We determine the various optical cross sections of such composite grains, given the optical properties of each constituent, using an approximate model of the composite grain. We assume it consists of many concentric spherical layers of the various materials, each with a specified volume fraction. In such a case the usual Mie theory can be generalized and the extinction, scattering, and other cross sections determined exactly. We find that the ordering of the materials in the layering makes some difference to the derived cross sections, but averaging over the various permutations of the order of the materials provides rapid convergence as the number of shells (each of which is filled by all of the materials proportionately to their volume fractions) is increased. Three shells, each with one layer of a particular constituent material, give a very satisfactory estimate of the average cross...

  15. SPIRE spectroscopy of the interstellar medium

    Science.gov (United States)

    Habart, E.; Dartois, E.; Abergel, A.; Baluteau, J.-P.; Naylor, D.; Polehampton, E.; Joblin, C.

    2010-12-01

    The SPIRE Fourier Transform Spectrometer on-board Herschel allows us, for the first time, to simultaneously measure the complete far-infrared spectrum from 194 to 671 μm. A wealth of rotational lines of CO (and its isotopologues), fine structure lines of C^0 and N^+, and emission lines from radicals and molecules has been observed towards several galactic regions and nearby galaxies. The strengths of the atomic and molecular lines place fundamental constraints on the physical conditions but also the chemistry of the interstellar medium. FTS mapping capabilities are also extremely powerful in characterizing the spatial morphology of the extended region and understand how the gas properties vary within the studied region. Here, we present a first analysis of SPIRE spectroscopic observations of the prototypical Orion Bar photodissociation region.

  16. Atom addition reactions in interstellar ice analogues

    CERN Document Server

    Linnartz, Harold; Fedoseev, Gleb

    2015-01-01

    This review paper summarizes the state-of-the-art in laboratory based interstellar ice chemistry. The focus is on atom addition reactions, illustrating how water, carbon dioxide and methanol can form in the solid state at astronomically relevant temperatures, and also the formation of more complex species such as hydroxylamine, an important prebiotic molecule, and glycolaldehyde, the smallest sugar, is discussed. These reactions are particularly relevant during the dark ages of star and planet formation, i.e., when the role of UV light is restricted. A quantitative characterization of such processes is only possible through dedicated laboratory studies, i.e., under full control of a large set of parameters such as temperature, atom-flux, and ice morphology. The resulting numbers, physical and chemical constants, e.g., barrier heights, reaction rates and branching ratios, provide information on the molecular processes at work and are needed as input for astrochemical models, in order to bridge the timescales t...

  17. Cometary Refractory Grains: Interstellar and Nebular Sources

    Science.gov (United States)

    Wooden, D. H.

    2008-07-01

    Comets are heterogeneous mixtures of interstellar and nebular materials. The degree of mixing of interstellar sources and nebular sources at different nuclear size scales holds the promise of revealing how cometary particles, cometesimals, and cometary nuclei accreted. We can ascribe cometary materials to interstellar and nebular sources and see how comets probe planet-forming process in our protoplanetary disk. Comets and cometary IDPs contain carbonaceous matter that appears to be either similar to poorly-graphitized (amorphous) carbon, a likely ISM source, or highly labile complex organics, with possible ISM or outer disk heritage. The oxygen fugacity of the solar nebula depends on the dynamical interplay between the inward migration of carbon-rich grains and of icy (water-rich) grains. Inside the water dissociation line, OH- reacts with carbon to form CO or CO2, consuming available oxygen and contributing to the canonical low oxygen fugacity. Alternatively, the influx of water vapor and/or oxygen rich dust grains from outer (cooler) disk regions can raise the oxygen fugacity. Low oxygen fugacity of the canonical solar nebula favors the condensation of Mg-rich crystalline silicates and Fe-metal, or the annealing of Fe-Mg amorphous silicates into Mg-rich crystals and Fe-metal via Fe-reduction. High oxygen fugacity nebular conditions favors the condensation of Fe-bearing to Fe-rich crystalline silicates. In the ISM, Fe-Mg amorphous silicates are prevalent, in stark contrast to Mg-rich crystalline silicates that are rare. Hence, cometary Mg-rich crystalline silicates formed in the hot, inner regions of the canonical solar nebula and they are the touchstone for models of the outward radial transport of nebular grains to the comet-forming zone. Stardust samples are dominated by Mg-rich crystalline silicates but also contain abundant Fe-bearing and Fe-rich crystalline silicates that are too large (≫0.1 μm) to be annealed Fe-Mg amorphous silicates. By comparison

  18. Radio search for interstellar phosphorus compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, J.M.; Snyder, L.E.; Lovas, F.J.; Ulich, B.L.

    1980-10-01

    The J=1--0 and 3--2 transitions of phosphorus nitride, PN, with resolvable hyperfine components at 46.99 GHz and blended components at 140.97 GHz, and transitions of phosphine, PH/sub 3/, at 47.39 and 46.94 GHz, arising from a small induced dipole moment, have been searched for but not found in interstellar molecular clouds. The J=3/2--1/2, F=3/2--3/2 transition of nitric oxide, NO, and the J/sub K/-K+=16/sub 4,12/15/sub 5,11/ transition of sulfur dioxide, SO/sub 2/, have been detected in Orion and Sagittarius B2. An unidentified emission line, U140921.8 MHz, has been observed in IRC+10216.

  19. A radio search for interstellar phosphorus compounds

    Science.gov (United States)

    Hollis, J. M.; Snyder, L. E.; Lovas, F. J.; Ulich, B. L.

    1980-01-01

    The J = 1-0 and 3-2 transitions of phosphorus nitride, PN, with resolvable hyperfine components at 46.99 GHz and blended components at 140.97 GHz, and transitions of phosphine, PH3, at 47.39 and 46.94 GHz, arising from a small induced dipole moment, have been searched for but not found in interstellar molecular clouds. The J = 3/2-1/2, F - 3/2-3/2 transition of nitric oxide, NO, and the J(K-K+) = 16(4, 12) -15(5, 11) transition of sulfur dioxide, SO2, have been detected in Orion and Sagittarius B2. An unidentified emission line, U140921.8 MHz, has been observed in IRC + 10216.

  20. A speckle hologram of the interstellar plasma

    Science.gov (United States)

    Desai, K. M.; Gwinn, C. R.; Reynolds, J.; King, E. A.; Jauncey, D.; Flanagan, C.; Nicolson, G.; Preston, R. A.; Jones, D. L.

    1992-01-01

    Observations of a speckle hologram of scattering material along the line of sight to the Vela pulsar indicate that this material is concentrated in the Vela supernova remnant, deep within the Gum Nebula. The speckle hologram is observed through the amplitude and phase variations of the interferometric cross-power spectrum with time and frequency. These variations describe the density fluctuations of the interstellar plasma, in a holographic fashion. The decorrelation due to the phase variations of the speckles yields the angular size of the scattering disk; comparison with the bandwidth of their amplitude variations yields a characteristic distance from earth to the scattering material of 0.81 +/- 0.03 of the distance from earth to the pulsar. This result is consistent with theories of irregularities associated with particle acceleration in shocks in supernova remnants.

  1. Thermal instability in the interstellar medium

    Directory of Open Access Journals (Sweden)

    J. Ghanbari

    2000-06-01

    Full Text Available   This study demonstrates how thermal structures in the interstellar medium can emerge as a result of thermal instability. For a two-dimensional case, the steady state thermal structures was investigeted and it was shown that a large class of solutions exist. For a one –dimensional case the conductivity was found to be negligible. The effects of to cal cooling on the thermal instability were explored in some depth. In this case analytical results for time-dependent cooling function were presented, too. We studied nonlinear wave phenomena in thermal fluid systems, with a particular emphasis on presenting analytical results. When conductivity is proportional to temperature, the beliavior of thermal waves is soliton like. For slow thermal waves, approximate analytical results were presented. Extensions of this work are discussed briefly, together with possible astrophysical applications.

  2. Scattering by interstellar graphite dust analog

    Science.gov (United States)

    Ahmed, Gazi A.; Gogoi, Ankur

    2014-10-01

    The analysis of optical scattering data of interstellar carbonaceous graphite dust analog at 543.5 nm, 594.5 nm and 632.8 nm laser wavelengths by using an original laboratory light scattering setup is presented. The setup primarily consisted of a laser source, optical units, aerosol sprayer, data acquisition system and associated instrumentation. The instrument measured scattered light signals from 10° to 170° in steps of 1°. The results of the measurements of the volume scattering function β(θ) and degree of linear polarization P(θ) of the carbonaceous graphite dust particles that were sprayed in front of the laser beam by using an aerosol sprayer were subsequently compared with theoretically generated Mie plots with estimated parameters.

  3. Molecular hydrogen formation in the interstellar medium

    CERN Document Server

    Cazaux, S

    2002-01-01

    We have developed a model for molecular hydrogen formation under astrophysically relevant conditions. This model takes fully into account the presence of both physisorbed and chemisorbed sites on the surface, allows quantum mechanical diffusion as well as thermal hopping for absorbed H-atoms, and has been benchmarked versus recent laboratory experiments on H2 formation on silicate surfaces. The results show that H2 formation on grain surface is efficient in the interstellar medium up to some 300K. At low temperatures (<100K), H2 formation is governed by the reaction of a physisorbed H with a chemisorbed H. At higher temperatures, H2 formation proceeds through reaction between two chemisorbed H atoms. We present simple analytical expressions for H2 formation which can be adopted to a wide variety of surfaces once their surfaces characteristics have been determined experimentally.

  4. Experimental Limit to Interstellar 244Pu Abundance

    CERN Document Server

    Paul, M; Ahmad, I; Berkovits, D; Bordeanu, C; Ghelberg, S; Hashimoto, Y; Hershcovitch, A I; Jiang, S; Nakanishi, T; Sakamoto, K

    2001-01-01

    Short-lived nuclides, now extinct in the solar system, are expected to be present in the interstellar medium (ISM). Grains of ISM origin were recently discovered in the inner solar system and at Earth orbit and may accrete onto Earth after ablation in the atmosphere. A favorable matrix for detection of such extraterrestrial material is presented by deep open-sea sediments with very low sedimentation rates (0.8-3 mm/kyr). We report here on the measurement of Pu isotopic abundances in a 1-kg deep-sea dry sediment collected in 1992 in the North Pacific. Our measured value of (3+-3)x10^5 244Pu atoms in the Pu-separated fraction of the sample shows no excess over the expected stratospheric nuclear fallout content and under reasonable assumptions we derive a limit of 2x10^-11 g-244Pu/g-ISM for the abundance of 244Pu in ISM.

  5. Predicted profiles of ultraviolet interstellar absorption lines

    Energy Technology Data Exchange (ETDEWEB)

    Welty, D.E.; Hobbs, L.M.; York, D.G. (Chicago, University, IL (USA))

    1991-02-01

    In this paper, values of the column density, line width parameter, and velocity are determined for as many components derived from optical interstellar absorption-line profiles of Na I and K I as needed to reproduce the observed high-resolution optical profiles of the D lines of Na I toward eight lightly reddened stars and of the 7698 A line of K I toward six moderately reddened stars. The derived component structures are then used to predict UV absorption-line profiles due to C I, Mg I, S I, Si I, and Fe I along the same lines of sight. Comparison of the predicted profiles with existing lower resolution line profiles and equivalent width data suggests that this simple scaling procedure can in many cases fairly reliably predict the UV profiles from the observed optical ones. 64 refs.

  6. From Interstellar PAHs and Ices to the Origin of Life

    Science.gov (United States)

    Allamandola, Louis J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Tremendous strides have been made in our understanding of interstellar material over the past twenty years thanks to significant, parallel developments in observational astronomy and laboratory astrophysics. Twenty years ago the composition of interstellar dust was largely guessed at, the concept of ices in dense molecular clouds ignored, and the notion of large, abundant, gas phase, carbon rich molecules widespread throughout the interstellar medium (ISM) considered impossible. Today the composition of dust in the diffuse ISM is reasonably well constrained to micron-sized cold refractory materials comprised of amorphous and crystalline silicates mixed with an amorphous carbonaceous material containing aromatic structural units and short, branched aliphatic chains. In dense molecular clouds, the birthplace of stars and planets, these cold dust particles are coated with mixed molecular ices whose composition is very well constrained. Lastly, the signature of carbon-rich polycyclic aromatic hydrocarbons (PAHs), shockingly large molecules by earlier interstellar chemistry standards, is widespread throughout the Universe. The first part of this lecture will describe how infrared studies of interstellar space, combined with laboratory simulations, have revealed the composition of interstellar ices (the building blocks of comets) and the high abundance and nature of interstellar PAHs. The laboratory database has now enabled us to gain insight into the identities, concentrations, and physical state of many interstellar materials. Within a dense molecular cloud, and especially in the solar nebula during the star and planet formation stage, the materials frozen into interstellar/precometary ices are photoprocessed by ultraviolet light, producing more complex molecules. The remainder of the presentation will focus on the photochemical evolution of these materials and the possible role of these compounds on the early Earth. As these materials are thought to be the building

  7. Realistic Detectability of Close Interstellar Comets

    Science.gov (United States)

    Cook, Nathaniel V.; Ragozzine, Darin; Granvik, Mikael; Stephens, Denise C.

    2016-07-01

    During the planet formation process, billions of comets are created and ejected into interstellar space. The detection and characterization of such interstellar comets (ICs) (also known as extra-solar planetesimals or extra-solar comets) would give us in situ information about the efficiency and properties of planet formation throughout the galaxy. However, no ICs have ever been detected, despite the fact that their hyperbolic orbits would make them readily identifiable as unrelated to the solar system. Moro-Martín et al. have made a detailed and reasonable estimate of the properties of the IC population. We extend their estimates of detectability with a numerical model that allows us to consider “close” ICs, e.g., those that come within the orbit of Jupiter. We include several constraints on a “detectable” object that allow for realistic estimates of the frequency of detections expected from the Large Synoptic Survey Telescope (LSST) and other surveys. The influence of several of the assumed model parameters on the frequency of detections is explored in detail. Based on the expectation from Moro-Martín et al., we expect that LSST will detect 0.001-10 ICs during its nominal 10 year lifetime, with most of the uncertainty from the unknown number density of small (nuclei of ˜0.1-1 km) ICs. Both asteroid and comet cases are considered, where the latter includes various empirical prescriptions of brightening. Using simulated LSST-like astrometric data, we study the problem of orbit determination for these bodies, finding that LSST could identify their orbits as hyperbolic and determine an ephemeris sufficiently accurate for follow-up in about 4-7 days. We give the hyperbolic orbital parameters of the most detectable ICs. Taking the results into consideration, we give recommendations to future searches for ICs.

  8. TRES survey of variable diffuse interstellar bands

    Science.gov (United States)

    Law, Charles J.; Milisavljevic, Dan; Crabtree, Kyle N.; Johansen, Sommer L.; Patnaude, Daniel J.; Margutti, Raffaella; Parrent, Jerod T.; Drout, Maria R.; Sanders, Nathan E.; Kirshner, Robert P.; Latham, David W.

    2017-09-01

    Diffuse interstellar bands (DIBs) are absorption features commonly observed in optical/near-infrared spectra of stars and thought to be associated with polyatomic molecules that comprise a significant reservoir of organic material in the Universe. However, the central wavelengths of almost all DIBs do not correspond with electronic transitions of known atomic or molecular species and the specific physical nature of their carriers remains inconclusive despite decades of observational, theoretical and experimental research. It is well established that DIB carriers are located in the interstellar medium, but the recent discovery of time-varying DIBs in the spectra of the extragalactic supernova SN 2012ap suggests that some may be created in massive star environments. Here, we report evidence of short time-scale (∼10-60 d) changes in DIB absorption line substructure towards 3 of 17 massive stars observed as part of a pathfinder survey of variable DIBs conducted with the 1.5-m Tillinghast telescope and Tillinghast Reflector Echelle Spectrograph (TRES) at Fred L. Whipple Observatory. The detections are made in high-resolution optical spectra (R ∼ 44 000) having signal-to-noise ratios of 5-15 around the 5797 and 6614 Å features, and are considered significant but requiring further investigation. We find that these changes are potentially consistent with interactions between stellar winds and DIB carriers in close proximity. Our findings motivate a larger survey to further characterize these variations and may establish a powerful new method for probing the poorly understood physical characteristics of DIB carriers.

  9. Improving practical sensitivity of energy optimized wake-up receivers: proof of concept in 65nm CMOS

    OpenAIRE

    Mazloum, Nafiseh Seyed; Rodrigues, Joachim Neves; Andersson, Oskar; Nejdel, Anders; Edfors, Ove

    2016-01-01

    We present a high performance low-power digital base-band architecture, specially designed for an energy optimized duty-cycled wake-up receiver scheme. Based on a careful wake-up beacon design, a structured wake-up beacon detection technique leads to an architecture that compensates for the implementation loss of a low-power wake-up receiver front-end at low energy and area costs. Design parameters are selected by energy optimization and the architecture is easily scalable to support various ...

  10. Applications of the Electrodynamic Tether to Interstellar Travel

    Science.gov (United States)

    Matloff, Gregory L.; Johnson, Les

    2005-01-01

    After considering relevant properties of the local interstellar medium and defining a sample interstellar mission, this paper considers possible interstellar applications of the electrodynamic tether, or EDT. These include use of the EDT to provide on-board power and affect trajectory modifications and direct application of the EDT to starship acceleration. It is demonstrated that comparatively modest EDTs can provide substantial quantities of on-board power, if combined with a large-area electron-collection device such as the Cassenti toroidal-field ramscoop. More substantial tethers can be used to accomplish large-radius thrustless turns. Direct application of the EDT to starship acceleration is apparently infeasible.

  11. Aspects of the interstellar medium in starburst galaxies

    Science.gov (United States)

    Fanelli, Michael N.

    1990-01-01

    Researchers are engaged in a multifaceted program to investigate the stellar content and star formation history of actively star-forming galaxies. A large body of stellar spectra have been examined to identify spectral features characteristic of specific stellar types. These spectral diagnostics are then calibrated in terms of temperature (spectral type), gravity (luminosity class) and metallicity. The spectral data is compiled into a stellar library whose members represent specific locations in the HR diagram. Through the use of population synthesis techniques, both optimizing and evolutionary approaches, the stellar luminosity function in composite populations can be determined by analysis of their integrated light. Researchers have concentrated on the ultraviolet wavelength region (lambda lambda 1200 to 3200), utilizing the International Ultraviolet Explorer (IUE) archives supplemented by additional observations. In the optical, virtually all stars will contribute to the integrated light. In the ultraviolet however, cool stars will produce negligible flux due to their steep ultraviolet-to-visual continua, greatly simplifying the investigation of the hot component in a composite population. The researchers' initial stellar library has been applied to several blue compact galaxies, (BCGs), a class of starburst galaxy which is UV luminous. BCGs possess a complex interstellar medium which affects the emergent stellar continuum in several ways. This presents a challenge to the stellar analysis but affords insight into the properties of the gas and dust from which the massive OB stars have formed. The optimizing synthesis method solves for the stellar luminosity function and extinction simultaneously. This therefore provides an independent measure of the extinction affecting the hot population component. Despite the rise of the reddening law towards the ultraviolet, BCGs are found to be brighter in the ultraviolet than expected.

  12. Mega-nano detection of foodborne pathogens and transgenes using molecular beacon and semiconductor quantum dot technologies.

    Science.gov (United States)

    Burris, Kellie P; Wu, Tsai-Chin; Vasudev, Milana; Stroscio, Michael A; Millwood, Reginald J; Stewart, C Neal

    2013-09-01

    Signature molecules derived from Listeria monocytogenes, Bacillus thuringiensis, and Salmonella Typhimurium were detected directly on food substrates (mega) by coupling molecular beacon technology utilizing fluorescent resonance energy transfer (FRET), luminescent nanoscale semiconductor quantum dots, and nanoscale quenchers. We designed target DNA sequences for detecting hlyA, Bt cry1Ac, and invA genes from L. monocytogenes, B. thuringiensis and Salmonella Typhimurium, respectively, and prepared molecular beacons for specific targets for use in real-time monitoring. We successfully detected increased fluorescence in the presence of signature molecules at molecular beacon (MB) concentrations from 1.17 nM to 40 nM, depending upon system tested in (water, milk or plant leaves), respective target (hlyA, Bt cry1Ac, or invA) and genomic DNA target concentration (50-800 ng). We were able to detect bacterial genomic DNA derived from L. monocytogenes and Salmonella sp. in a food system, 2% milk ( > 20% of total volume). Furthermore, we infiltrated the Bt cry1Ac beacon in the presence of genomic DNA extracted from B. thuringiensis into Arabidopsis thaliana leaves and observed increased fluorescence in the presence of the target, indicating the ability to use these beacons in a plant system.

  13. Combining Magnetic and Electric Sails for Interstellar Deceleration

    CERN Document Server

    Perakis, Nikolaos

    2016-01-01

    The main benefit of an interstellar mission is to carry out in-situ measurements within a target star system. To allow for extended in-situ measurements, the spacecraft needs to be decelerated. One of the currently most promising technologies for deceleration is the magnetic sail which uses the deflection of interstellar matter via a magnetic field to decelerate the spacecraft. However, while the magnetic sail is very efficient at high velocities, its performance decreases with lower speeds. This leads to deceleration durations of several decades depending on the spacecraft mass. Within the context of Project Dragonfly, initiated by the Initiative of Interstellar Studies (i4is), this paper proposes a novel concept for decelerating a spacecraft on an interstellar mission by combining a magnetic sail with an electric sail. Combining the sails compensates for each technologys shortcomings: A magnetic sail is more effective at higher velocities than the electric sail and vice versa. It is demonstrated that using ...

  14. Ionization of Interstellar Hydrogen Beyond the Termination Shock

    Science.gov (United States)

    Gruntman, Mike

    2016-11-01

    Models of solar wind interaction with the surrounding interstellar medium usually disregard ionization of interstellar hydrogen atoms beyond the solar wind termination shock. If and when included, the effects of ionization in the heliospheric interface region are often obscured by complexities of the interaction. This work assesses the importance of interstellar hydrogen ionization in the heliosheath. Photoionization could be accounted for in a straightforward way. In contrast, electron impact ionization is largely unknown because of poorly understood energy transfer to electrons at the termination shock and beyond. We first estimate the effect of photoionization and then use it as a yardstick to assess the role of electron impact ionization. The physical estimates show that ionization of interstellar hydrogen may lead to significant mass loading in the inner heliosheath which would slow down plasma flowing toward the heliotail and deplete populations of nonthermal protons, with the corresponding effect on heliospheric fluxes of energetic neutral atoms.

  15. Multiphase turbulent interstellar medium: some recent results from radio astronomy

    CERN Document Server

    Roy, Nirupam

    2015-01-01

    The radio frequency 1.4 GHz transition of the atomic hydrogen is one of the important tracers of the diffuse neutral interstellar medium. Radio astronomical observations of this transition, using either a single dish telescope or an array interferometer, reveal different properties of the interstellar medium. Such observations are particularly useful to study the multiphase nature and turbulence in the interstellar gas. Observations with multiple radio telescopes have recently been used to study these two closely related aspects in greater detail. Using various observational techniques, the density and the velocity fluctuations in the Galactic interstellar medium was found to have a Kolmogorov-like power law power spectra. The observed power law scaling of the turbulent velocity dispersion with the length scale can be used to derive the true temperature distribution of the medium. Observations from a large ongoing atomic hydrogen absorption line survey have also been used to study the distribution of gas at d...

  16. Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules.

    Science.gov (United States)

    Öberg, Karin I

    2016-09-14

    The interstellar medium is characterized by a rich and diverse chemistry. Many of its complex organic molecules are proposed to form through radical chemistry in icy grain mantles. Radicals form readily when interstellar ices (composed of water and other volatiles) are exposed to UV photons and other sources of dissociative radiation, and if sufficiently mobile the radicals can react to form larger, more complex molecules. The resulting complex organic molecules (COMs) accompany star and planet formation and may eventually seed the origins of life on nascent planets. Experiments of increasing sophistication have demonstrated that known interstellar COMs as well as the prebiotically interesting amino acids can form through ice photochemistry. We review these experiments and discuss the qualitative and quantitative kinetic and mechanistic constraints they have provided. We finally compare the effects of UV radiation with those of three other potential sources of radical production and chemistry in interstellar ices: electrons, ions, and X-rays.

  17. The Interstellar Medium in External Galaxies: Summaries of contributed papers

    Science.gov (United States)

    Hollenbach, David J. (Editor); Thronson, Harley A., Jr. (Editor)

    1990-01-01

    The Second Wyoming Conference entitled, The Interstellar Medium in External Galaxies, was held on July 3 to 7, 1989, to discuss the current understanding of the interstellar medium in external galaxies and to analyze the basic physical processes underlying interstellar phenomena. The papers covered a broad range of research on the gas and dust in external galaxies and focused on such topics as the distribution and morphology of the atomic, molecular, and dust components; the dynamics of the gas and the role of the magnetic field in the dynamics; elemental abundances and gas depletions in the atomic and ionized components; cooling flows; star formation; the correlation of the nonthermal radio continuum with the cool component of the interstellar medium; the origin and effect of hot galactic halos; the absorption line systems seen in distant quasars; and the effect of galactic collisions.

  18. The crystalline fraction of interstellar silicates in starburst galaxies

    CERN Document Server

    Kemper, F; Woods, Paul M

    2010-01-01

    We present a model using the evolution of the stellar population in a starburst galaxy to predict the crystallinity of the silicates in the interstellar medium of this galaxy. We take into account dust production in stellar ejecta, and amorphisation and destruction in the interstellar medium and find that a detectable amount of crystalline silicates may be formed, particularly at high star formation rates, and in case supernovae are efficient dust producers. We discuss the effect of dust destruction and amorphisation by supernovae, and the effect of a low dust-production efficiency by supernovae, and find that when taking this into account, crystallinity in the interstellar medium becomes hard to detect. Levels of 6.5-13% crystallinity in the interstellar medium of starburst galaxies have been observed and thus we conclude that not all these crystalline silicates can be of stellar origin, and an additional source of crystalline silicates associated with the Active Galactic Nucleus must be present.

  19. In situ observations of interstellar plasma with Voyager 1.

    Science.gov (United States)

    Gurnett, D A; Kurth, W S; Burlaga, L F; Ness, N F

    2013-09-27

    Launched over 35 years ago, Voyagers 1 and 2 are on an epic journey outward from the Sun to reach the boundary between the solar plasma and the much cooler interstellar medium. The boundary, called the heliopause, is expected to be marked by a large increase in plasma density, from about 0.002 per cubic centimeter (cm(-3)) in the outer heliosphere, to about 0.1 cm(-3) in the interstellar medium. On 9 April 2013, the Voyager 1 plasma wave instrument began detecting locally generated electron plasma oscillations at a frequency of about 2.6 kilohertz. This oscillation frequency corresponds to an electron density of about 0.08 cm(-3), very close to the value expected in the interstellar medium. These and other observations provide strong evidence that Voyager 1 has crossed the heliopause into the nearby interstellar plasma.

  20. Tentative Identification of Interstellar Dust in Heliosphere Nose

    CERN Document Server

    Frisch, P C

    2005-01-01

    Observations of polarization toward nearby stars in the upwind direction made by (Tinbergen, 1982) are consistent with an origin associated with interstellar dust grains entrained in interstellar magnetic fields wrapped around the heliosphere nose. The region of maximum polarization is centered around ecliptic coordinates (295 deg,0 deg). The direction of maximum polarization is offset along the ecliptic longitude by about 35 deg from the heliosphere nose. An offset is also seen between the region with the best aligned dust grains (ecliptic longitudes 281 deg to 330 deg) and inflowing interstellar dust grains observed by Ulysses and Galileo, and in this region polarization strength anti-correlates with ecliptic latitude. These offsets support an interpretation whereby the maximum polarization occurs in a direction perpendicular to the interstellar field lines, the region of consistent polarization angle shows the deflection of small grains, and the inflow of larger grains shows the undeflected grain populatio...

  1. Starry Messages: Searching for Signatures of Interstellar Archaeology

    CERN Document Server

    Carrigan, Richard A

    2010-01-01

    Searching for signatures of cosmic-scale archaeological artifacts such as Dyson spheres or Kardashev civilizations is an interesting alternative to conventional SETI. Uncovering such an artifact does not require the intentional transmission of a signal on the part of the original civilization. This type of search is called interstellar archaeology or sometimes cosmic archaeology. The detection of intelligence elsewhere in the Universe with interstellar archaeology or SETI would have broad implications for science. For example, the constraints of the anthropic principle would have to be loosened if a different type of intelligence was discovered elsewhere. A variety of interstellar archaeology signatures are discussed including non-natural planetary atmospheric constituents, stellar doping with isotopes of nuclear wastes, Dyson spheres, as well as signatures of stellar and galactic-scale engineering. The concept of a Fermi bubble due to interstellar migration is introduced in the discussion of galactic signatu...

  2. The prebiotic synthesis of amino acids - interstellar vs. atmospheric mechanisms

    Science.gov (United States)

    Meierhenrich, U. J.; Muñoz Caro, G. M.; Schutte, W. A.; Barbier, B.; Arcones Segovia, A.; Rosenbauer, H.; Thiemann, W. H.-P.; Brack, A.

    2002-11-01

    Until very recently, prebiotic amino acids were believed to have been generated in the atmosphere of the early Earth, as successfully simulated by the Urey-Miller experiments. Two independent studies now identified ice photochemistry in the interstellar medium as a possible source of prebiotic amino acids. Ultraviolet irradiation of ice mixtures containing identified interstellar molecules (such as H2O, CO2, CO, CH3OH, and NH3) in the conditions of vacuum and low temperature found in the interstellar medium generated amino acid structures including glycine, alanine, serine, valine, proline, and aspartic acid. After warmup, hydrolysis and derivatization, our team was able to identify 16 amino acids as well as furans and pyrroles. Enantioselective analyses of the amino acids showed racemic mixtures. A prebiotic interstellar origin of amino acid structures is now discussed to be a plausible alternative to the Urey-Miller mechanism.

  3. On the maximum sufficient range of interstellar vessels

    CERN Document Server

    Cartin, Daniel

    2011-01-01

    This paper considers the likely maximum range of space vessels providing the basis of a mature interstellar transportation network. Using the principle of sufficiency, it is argued that this range will be less than three parsecs for the average interstellar vessel. This maximum range provides access from the Solar System to a large majority of nearby stellar systems, with total travel distances within the network not excessively greater than actual physical distance.

  4. Refractive Interstellar Scintillation for Flux Density Variations of Two Pulsars

    Institute of Scientific and Technical Information of China (English)

    周爱芝; 吴鑫基; 艾力·伊沙木丁

    2003-01-01

    The flux density structure functions of PSRs B0525+21 and B2111+46 are calculated with the refractive interstellar scintillation (RISS) theory. The theoretical curves are in good agreement with observations [Astrophys.J. 539 (2000) 300] (hereafter S2000). The spectra of the electron density fluctuations both are of Kolmogorov spectra. We suggest that the flux density variations observed for these two pulsars are attributed to refractive interstellar scintillation, not to intrinsic variability.

  5. The interaction of the solar wind with the interstellar medium

    Science.gov (United States)

    Axford, W. I.

    1972-01-01

    The expected characteristics of the solar wind, extrapolated from the vicinity of the earth are described. Several models are examined for the interaction of the solar wind with the interstellar plasma and magnetic field. Various aspects of the penetration of neutral interstellar gas into the solar wind are considered. The dynamic effects of the neutral gas on the solar wind are described. Problems associated with the interaction of cosmic rays with the solar wind are discussed.

  6. Interstellar neutral flow characteristics, composition, and interaction with the heliosphere - neutral gas and pickup ion analysis from ongoing observations and perspectives for IMAP

    Science.gov (United States)

    Moebius, E.; Bzowski, M.; Drews, C.; Frisch, P. C.; Fuselier, S. A.; Galli, A.; Gloeckler, G.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Park, J.; Schwadron, N.; Swaczyna, P.; Sokol, J. M.; Wood, B. E.; Wurz, P.

    2015-12-01

    composition and secondary component observations. So far, PUIs have only been observed with sensors that were not optimized for interstellar PUIs. The Interstellar Mapping and Acceleration Probe (IMAP) to be placed at L1 will take these observations to the next level with more powerful sensors.

  7. Spatial distribution of interstellar dust in the Sun's vicinity. Comparison with neutral sodium-bearing gas

    Science.gov (United States)

    Vergely, J.-L.; Valette, B.; Lallement, R.; Raimond, S.

    2010-07-01

    Aims: 3D tomography of the interstellar dust and gas may be useful in many respects, from the physical and chemical evolution of the interstellar medium itself to foreground decontamination of the cosmic microwave background, or various studies of the environments of specific objects. However, while spectral data cubes of the galactic emission become increasingly precise, the information on the distance to the emitting regions has not progressed as well and relies essentially on the galactic rotation curve. Our goal here is to bring more precise information on the distance to nearby interstellar dust and gas clouds within 250 pc. Methods: We apply the best available calibration methods to a carefully screened set of stellar Strömgren photometry data for targets possessing a Hipparcos parallax and spectral type classification. We combine the derived interstellar extinctions and the parallax distances for about 6000 stars to build a 3D tomography of the local dust. We use an inversion method based on a regularized Bayesian approach and a least squares criterion, optimized for this specific data set. We apply the same inversion technique to a totally independent set of neutral sodium absorption data available for about 1700 target stars. Results: We obtain 3D maps of the opacity and the distance to the main dust-bearing clouds within 250 pc and identify in those maps well-known dark clouds and high galactic more diffuse entities. We calculate the integrated extinction between the Sun and the cube boundary and compare this with the total galactic extinction derived from infrared 2D maps. The two quantities reach similar values at high latitudes, as expected if the local dust content is satisfyingly reproduced and the dust is closer than 250 pc. Those maps show a larger high latitude dust opacity in the North compared to the South, reinforcing earlier evidences. Interestingly the gas maps do not show the same asymmetry, suggesting a polar asymmetry of the dust to gas

  8. Starry messages: Searching for signatures of interstellar archaeology

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, Richard A., Jr.; /Fermilab

    2009-12-01

    Searching for signatures of cosmic-scale archaeological artifacts such as Dyson spheres or Kardashev civilizations is an interesting alternative to conventional SETI. Uncovering such an artifact does not require the intentional transmission of a signal on the part of the original civilization. This type of search is called interstellar archaeology or sometimes cosmic archaeology. The detection of intelligence elsewhere in the Universe with interstellar archaeology or SETI would have broad implications for science. For example, the constraints of the anthropic principle would have to be loosened if a different type of intelligence was discovered elsewhere. A variety of interstellar archaeology signatures are discussed including non-natural planetary atmospheric constituents, stellar doping with isotopes of nuclear wastes, Dyson spheres, as well as signatures of stellar and galactic-scale engineering. The concept of a Fermi bubble due to interstellar migration is introduced in the discussion of galactic signatures. These potential interstellar archaeological signatures are classified using the Kardashev scale. A modified Drake equation is used to evaluate the relative challenges of finding various sources. With few exceptions interstellar archaeological signatures are clouded and beyond current technological capabilities. However SETI for so-called cultural transmissions and planetary atmosphere signatures are within reach.

  9. Matrix isolation as a tool for studying interstellar chemical reactions

    Science.gov (United States)

    Ball, David W.; Ortman, Bryan J.; Hauge, Robert H.; Margrave, John L.

    1989-01-01

    Since the identification of the OH radical as an interstellar species, over 50 molecular species were identified as interstellar denizens. While identification of new species appears straightforward, an explanation for their mechanisms of formation is not. Most astronomers concede that large bodies like interstellar dust grains are necessary for adsorption of molecules and their energies of reactions, but many of the mechanistic steps are unknown and speculative. It is proposed that data from matrix isolation experiments involving the reactions of refractory materials (especially C, Si, and Fe atoms and clusters) with small molecules (mainly H2, H2O, CO, CO2) are particularly applicable to explaining mechanistic details of likely interstellar chemical reactions. In many cases, matrix isolation techniques are the sole method of studying such reactions; also in many cases, complexations and bond rearrangements yield molecules never before observed. The study of these reactions thus provides a logical basis for the mechanisms of interstellar reactions. A list of reactions is presented that would simulate interstellar chemical reactions. These reactions were studied using FTIR-matrix isolation techniques.

  10. VUV spectroscopy of carbon dust analogs: contribution to interstellar extinction

    Science.gov (United States)

    Gavilan, L.; Alata, I.; Le, K. C.; Pino, T.; Giuliani, A.; Dartois, E.

    2016-02-01

    Context. A full spectral characterization of carbonaceous dust analogs is necessary to understand their potential as carriers of observed astronomical spectral signatures such as the ubiquitous UV bump at 217.5 nm and the far-ultraviolet (FUV) rise common to interstellar extinction curves. Aims: Our goal is to study the spectral properties of carbonaceous dust analogs from the FUV to the mid-infrared (MIR) domain. We seek in particular to understand the spectra of these materials in the FUV range, for which laboratory studies are scarce. Methods: We produced analogs to carbonaceous interstellar dust encountered in various phases of the interstellar medium: amorphous hydrogenated carbons (a-C:H), for carbonaceous dust observed in the diffuse interstellar medium, and soot particles, for the polyaromatic component. Analogs to a-C:H dust were produced using a radio-frequency plasma reactor at low pressures, and soot nanoparticles films were produced in an ethylene (C2H4) flame. We measured transmission spectra of these thin films (thickness Kronig inversion. We used these constants for comparison to existing interstellar extinction curves. Conclusions: We extend the spectral measurements of these types of carbonaceous analogs into the VUV and link the spectral features in this range to the 3.4 μm band. We suggest that these two materials might contribute to different classes of interstellar extinction curves.

  11. Starry Messages - Searching for Signatures of Interstellar Archaeology

    Science.gov (United States)

    Carrigan, R. A., Jr.

    Searching for signatures of cosmic-scale archaeological artefacts such as Dyson spheres or Kardashev civilizations is an interesting alternative to conventional SETI. Uncovering such an artifact does not require the intentional transmission of a signal on the part of the originating civilization. This type of search is called interstellar archaeology or sometimes cosmic archaeology . The detection of intelligence elsewhere in the Universe with interstellar archaeology or SETI would have broad implications for science. For example, the constraints of the anthropic principle would have to be loosened if a different type of intelligence was discovered elsewhere. A variety of interstellar archaeology signatures are discussed including non-natural planetary atmospheric constituents, stellar doping with isotopes of nuclear wastes, Dyson spheres, as well as signatures of stellar and galactic-scale engineering. The concept of a Fermi bubble due to interstellar migration is introduced in the discussion of galactic signatures. These potential interstellar archaeological signatures are classified using the Kardashev scale. A modified Drake equation is used to evaluate the relative challenges of finding various sources. With few exceptions interstellar archaeological signatures are clouded and beyond current technological capabilities. However SETI for so-called cultural transmissions and planetary atmosphere signatures are within reach.

  12. The Interstellar Cloud Surrounding the Solar System

    Science.gov (United States)

    Frisch, P. C.

    Ultraviolet spectral data of nearby stars indicate that the cloud surrounding the solar system has an average neutral density n(HI)~0.1 cm-3, temperature ~6800 K, and turbulence ~1.7 km/s. Comparisons between the anomalous cosmic ray data and ultraviolet data suggest that the electron density is in the range n(e-)~0.22 to 0.44 cm-3. This cloud is flowing past the Sun from a position centered in the Norma-Lupis region. The cloud properties are consistent with interstellar gas which originated as material evaporated from the surfaces of embedded clouds in the Scorpius-Centaurus Association, and which was then displaced towards the Sun by a supernova event about 4 Myrs ago. The Sun and surrounding cloud velocities are nearly perpendicular in space, and this cloud is sweeping past the Sun. The morphology of this cloud can be reconstructed by assuming that the cloud moves in a direction parallel to the surface normal. With this assumption, the Sun entered the surrounding cloud 2000 to 8000 years ago, and is now about 0.05 to 0.16 pc from the cloud surface. Prior to its recent entry into the surrounding cloud complex, the Sun was embedded in a region of space with average density lower than 0.0002 cm-3. If a denser cloud velocity component seen towards alpha Cen A,B is real, it will encounter the solar system within 50,000 yr. The nearby magnetic field seen upwind has a spatial orientation that is parallel to the cloud surface. The nearby star Sirius is viewed through the wake of the solar system, but this direction also samples the hypothetical cloud interface. Comparisons of anomalous cosmic ray and interstellar absorption line data suggest that trace elements in the surrounding cloud are in ionization equilibrium. Data towards nearby white dwarfs indicate partial helium ionization, N(N(HI)(/N(HeI)>~13.7, which is consistent with pickup ion data within the solar system if less than 40% hydrogen ionization occurs in the heliopause region. However, the white dwarfs may

  13. Detection of Interstellar Urea with Carma

    Science.gov (United States)

    Kuo, H.-L.; Snyder, L. E.; Friedel, D. N.; Looney, L. W.; McCall, B. J.; Remijan, A. J.; Lovas, F. J.; Hollis, J. M.

    2010-06-01

    Urea, a molecule discovered in human urine by H. M. Rouelle in 1773, has a significant role in prebiotic chemistry. Previous BIMA observations have suggested that interstellar urea [(NH_2)_2CO] is a compact hot core molecule such as other large molecules, e.g. methyl formate and acetic acid (2009, 64th OSU Symposium On Molecular Spectroscopy, WI05). We have conducted an extensive search for urea toward the high mass hot molecular core Sgr B2(N-LMH) using CARMA and the IRAM 30 m. Because the spectral lines of heavy molecules like urea tend to be weak and hot cores display lines from a wide range of molecules, a major problem in identifying urea lines is confusion with lines of other molecules. Therefore, it is necessary to detect a number of urea lines and apply sophisticated statistical tests before having confidence in an identification. The 1 mm resolution of CARMA enables favorable coupling of the source size and synthesized beam size, which was found to be essential for the detection of weak signals. The 2.5^"×2^" synthesized beam of CARMA significantly resolves out the contamination by extended emission and reveals the eight weak urea lines that were previously blended with nearby transitions. Our analysis indicates that these lines are likely to be urea since the resulting observed line frequencies are coincident with a set of overlapping connecting urea lines, and the observed line intensities are consistent with the expected line strengths of urea. In addition, we have developed a new statistical approach to examine the spatial correlation between the observed lines by applying the Student T-test to the high resolution channel maps obtained from CARMA. The T-test shows similar spatial distributions from all eight candidate lines, suggesting a common molecular origin, urea. Our T-test method could have a broad impact on the next generation of arrays, such as ALMA, because the new arrays will require a method to systematically determine the credibility of

  14. Interstellar Mapping and Acceleration Probe (IMAP)

    Science.gov (United States)

    Schwadron, Nathan

    2016-04-01

    Our piece of cosmic real-estate, the heliosphere, is the domain of all human existence - an astrophysical case-history of the successful evolution of life in a habitable system. By exploring our global heliosphere and its myriad interactions, we develop key physical knowledge of the interstellar interactions that influence exoplanetary habitability as well as the distant history and destiny of our solar system and world. IBEX was the first mission to explore the global heliosphere and in concert with Voyager 1 and Voyager 2 is discovering a fundamentally new and uncharted physical domain of the outer heliosphere. In parallel, Cassini/INCA maps the global heliosphere at energies (~5-55 KeV) above those measured by IBEX. The enigmatic IBEX ribbon and the INCA belt were unanticipated discoveries demonstrating that much of what we know or think we understand about the outer heliosphere needs to be revised. The next quantum leap enabled by IMAP will open new windows on the frontier of Heliophysics at a time when the space environment is rapidly evolving. IMAP with 100 times the combined resolution and sensitivity of IBEX and INCA will discover the substructure of the IBEX ribbon and will reveal in unprecedented resolution global maps of our heliosphere. The remarkable synergy between IMAP, Voyager 1 and Voyager 2 will remain for at least the next decade as Voyager 1 pushes further into the interstellar domain and Voyager 2 moves through the heliosheath. The "A" in IMAP refers to acceleration of energetic particles. With its combination of highly sensitive pickup and suprathermal ion sensors, IMAP will provide the species and spectral coverage as well as unprecedented temporal resolution to associate emerging suprathermal tails with interplanetary structures and discover underlying physical acceleration processes. These key measurements will provide what has been a critical missing piece of suprathermal seed particles in our understanding of particle acceleration to high

  15. The Interstellar Boundary Explorer (IBEX): Tracing the Interaction between the Heliosphere and Surrounding Interstellar Material with Energetic Neutral Atoms

    CERN Document Server

    Frisch, Priscilla C

    2010-01-01

    The Interstellar Boundary Explorer (IBEX) mission is exploring the frontiers of the heliosphere where energetic neutral atoms (ENAs) are formed from charge exchange between interstellar neutral hydrogen atoms and solar wind ions and pickup ions. The geography of this frontier is dominated by an unexpected nearly complete arc of ENA emission, now known as the IBEX 'Ribbon'. While there is no consensus agreement on the Ribbon formation mechanism, it seems certain this feature is seen for sightlines that are perpendicular to the interstellar magnetic field as it drapes over the heliosphere. At the lowest energies, IBEX also measures the flow of interstellar H, He, and O atoms through the inner heliosphere. The asymmetric helium profile suggests that a secondary flow of helium is present, such as would be expected if some fraction of helium is lost through charge exchange in the heliosheath regions. The detailed spectra characterized by the ENAs provide time-tagged samples of the energy distributions of the under...

  16. Monte Carlo simulation of a gas measurement beacon: computation and validation, ASGA/VGM beacon; Simulation monte carlo d'une balise de mesures de gaz calcul et validation, balise ASGA/VGM

    Energy Technology Data Exchange (ETDEWEB)

    Ferragut, A. [Ste Saphymo, 5 rue du Theatre, 91884 Massy Cedex (France)

    2010-07-01

    The author reports a Monte Carlo simulation of a gas measurement sensor (ASGA or Ventilation Gas Monitor) used to monitor and detect radioactivity in the ventilation of the CERN's LHC (Large Hadron Collider). He recalls the performance required for these beacons, and the different factors governing their detection threshold. He discusses the possibilities offered by the GEANT4 code to model and simulation the beacon physics, and to generate events. Results are obtained in terms of spectrum of deposited energy. The author reports the sensitivity determination

  17. Molecular beacon probes-base multiplex NASBA Real-time for detection of HIV-1 and HCV.

    Science.gov (United States)

    Mohammadi-Yeganeh, S; Paryan, M; Mirab Samiee, S; Kia, V; Rezvan, H

    2012-06-01

    Developed in 1991, nucleic acid sequence-based amplification (NASBA) has been introduced as a rapid molecular diagnostic technique, where it has been shown to give quicker results than PCR, and it can also be more sensitive. This paper describes the development of a molecular beacon-based multiplex NASBA assay for simultaneous detection of HIV-1 and HCV in plasma samples. A well-conserved region in the HIV-1 pol gene and 5'-NCR of HCV genome were used for primers and molecular beacon design. The performance features of HCV/HIV-1 multiplex NASBA assay including analytical sensitivity and specificity, clinical sensitivity and clinical specificity were evaluated. The analysis of scalar concentrations of the samples indicated that the limit of quantification of the assay was beacon probes detected all HCV genotypes and all major variants of HIV-1. This method may represent a relatively inexpensive isothermal method for detection of HIV-1/HCV co-infection in monitoring of patients.

  18. Research on Beacon Hill School Education Practice%比肯山学校教育实践研究

    Institute of Scientific and Technical Information of China (English)

    张蔚

    2015-01-01

    比肯山学校是1927年由罗素夫妇创办的新式学校,罗素夫妇将他们的教育思想运用于实践。教育生态学、教育人类学、教育文化学和教育管理学等多学科的视角下对比肯山学校进行研究,从而考察比肯山学校所具有的历史价值。%Beacon Hill school is an new schools started by Russell couple on 1927. Russell couples are turning their ideas on education in practice. This article make an contrast study on Beacon Hill School from a multidisciplinary perspective of educational ecology, educational anthropology, science of culture and education management and so on, Thus investigate the historical value of the Beacon Hill school.

  19. Preliminary Results of the NASA Beacon Receiver for Alphasat Aldo Paraboni TDP5 Propagation Experiment

    Science.gov (United States)

    Nessel, James; Morse, Jacquelynne; Zemba, Michael; Riva, Carlo; Luini, Lorenzo

    2014-01-01

    NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 GHz band. NASA GRC has developed and installed a K/Q-band (20/40 GHz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 GHz signals broadcast from the Alphasat Aldo Paraboni TDP#5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we describe the design and preliminary performance of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The receiver is based upon a validated Fast Fourier Transform (FFT) I/Q digital design approach utilized in other operational NASA propagation terminals, but has been modified to employ power measurement via a frequency estimation technique and to coherently track and measure the amplitude of the 20/40 GHz beacon signals. The system consists of a 1.2-m K-band and a 0.6-m Qband Cassegrain reflector employing synchronous open-loop tracking to track the inclined orbit of the Alphasat satellite. An 8 Hz sampling rate is implemented to characterize scintillation effects, with a 1-Hz measurement bandwidth dynamic range of 45 dB. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.

  20. Performance of the NASA Beacon Receiver for the Alphasat Aldo Paraboni TDP5 Propagation Experiment

    Science.gov (United States)

    Nessel, James; Morse, Jacquelynne; Zemba, Michael; Riva, Carlo; Luini, Lorenzo

    2015-01-01

    NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 gigahertz band. NASA GRC has developed and installed a K/Q-band (20/40 gigahertz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 gigahertz signals broadcast from the Alphasat Aldo Paraboni Technology Demonstration Payload (TDP) no. 5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we describe the design and preliminary performance of the NASA propagation terminal, which has been installed and operating in Milan since June 2014. The receiver is based upon a validated Fast Fourier Transform (FFT) I/Q digital design approach utilized in other operational NASA propagation terminals, but has been modified to employ power measurement via a frequency estimation technique and to coherently track and measure the amplitude of the 20/40 gigahertz beacon signals. The system consists of a 1.2-meter K-band and a 0.6-meter Q-band Cassegrain reflector employing synchronous open-loop tracking to track the inclined orbit of the Alphasat satellite. An 8 hertz sampling rate is implemented to characterize scintillation effects, with a 1-hertz measurement bandwidth dynamic range of 45 decibels. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.