Science.gov

Sample records for frequency sweeper seeded

  1. Broadband lightwave synthesized frequency sweeper using self-induced auto-tracking filter.

    PubMed

    Wang, Zhaoying; Liu, Shiyuan; Luo, Sha; Yuan, Quan; Ma, Rui; Ge, Chunfeng; Yang, Tianxin

    2015-08-24

    We present a scheme to broaden the sweeping span of lightwave synthesized frequency sweeper (LSFS) by using self-induced auto-tracking filter (SIATF). It is based on spatial-hole-burning effect in unpumped erbium-doped fiber (EDF), equivalent to introducing a Bragg grating. This Bragg grating works as the SIAFT, tracks the frequency of the incident optical signal automatically. It broadens LSFS's sweeping span limited by the homogeneous broadening of EDF. The scheme is demonstrated experimentally that the amplified spontaneous emission (ASE) noise is effectively suppressed meanwhile sweeping span of LSFS is enlarged. 12.48nm sweeping span within 3.5dB power change is obtained, which corresponds to 1.56THz sweeping span. PMID:26368187

  2. Orbital debris sweeper and method

    NASA Technical Reports Server (NTRS)

    Petro, Andrew J. (Inventor)

    1991-01-01

    An orbital debris sweeper is provided for removing particles from orbit which otherwise may impact and damage an orbiting spacecraft. The debris sweeper includes a central sweeper core which carries a debris monitoring unit, and a plurality of large area impact panels rotatable about a central sweeper rotational axis. In response to information from the debris monitoring unit, a computer determines whether individual monitored particles preferably impact one of the rotating panels or pass between the rotating panels. A control unit extends or retracts one or more booms which interconnect the sweeper core and the panels to change the moment of inertia of the sweeper and thereby the rotational velocity of the rotating panels. According to the method of the present invention, the change in panel rotational velocity increases the frequency of particles which desirably impact one of the panels and are thereby removed from orbit, while large particles which may damage the impact panels pass between the trailing edge of one panel and the leading edge of the rotationally succeeding panel.

  3. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  4. Design, fabrication, installation, and testing of high energy sweeper

    SciTech Connect

    Ghosh, S.; Sarkar, A.; Sonti, S. S. K.; Rao, S.; Sivakumar, V. V.; Rai, A.; Barua, P.; Datta, S. K.; Bhowmik, R. K.; Roy, A.

    2006-07-15

    A room temperature high-energy sweeper had been designed, fabricated, and installed at the postacceleration section of the Tandem accelerator. The sweeper, a part of the new pulsing system, is being used to inject the bunched beam without dark current into the linear accelerator acting as a booster of the Tandem. The resonance frequency of the sweeper was set at 6.0625 MHz and a quality factor of {approx}1300 was achieved. During off-line testing of the sweeper, a deflector voltage of {approx}30 kV had been measured for an input power of 300 W. A pair of indigenously fabricated capacitors is used for fine-tuning of the resonance frequency. The silver plated coil of the tank circuit was fabricated with two concentric copper tubes. During the successful beam test of the sweeper, a peak to dark current ratio of 97% has been achieved.

  5. PERFORMANCE EVALUATION OF AN IMPROVED STREET SWEEPER

    EPA Science Inventory

    The report gives results of an extensive evaluation of the Improved Street Sweeper (ISS) in Bellevue, WA, and in San Diego, CA. The cleaning performance of the ISS was compared with that of broom sweepers and a vacuum sweeper. The ISS cleaned streets better than the other sweeper...

  6. Plasma sweeper. [Patents

    DOEpatents

    Motley, R.W.; Glanz, J.

    1982-10-25

    A device is described for coupling RF power (a plasma sweeper) from RF power introducing means to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the RF power introducing means. Means are described for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  7. Oil sweeper method and apparatus

    SciTech Connect

    De V. A.; Van W. P.

    1982-04-20

    Oil sweeper method and apparatus including an elongated structural framework adapted to be towed transversely across the surface of water bearing an oil film contaminant, the framework supporting a pair of longitudinally extending, parallel vertical screens, wherein the forwardmost screen relative to the direction of sweeping motion is constituted of multiple panels pivotally attached to the framework for swinging movement about vertical swinging axes, and the rearward screen is water impervious. When the panels of the forwardmost screen are pivoted they define channels therebetween for diverting surface water and floating contamination such as oil in a lateral direction towards a skimmer disposed at one end of the sweeper apparatus. The rearward screen assists in further deflecting the water and oil towards the skimmer after they have traversed the channels between the pivotable panels.

  8. Performance evaluation of an improved street sweeper

    SciTech Connect

    Duncan, M.W.; Jain, R.C.; Yung, S.C.; Patterson, R.G.

    1985-10-01

    The paper gives results of an evaluation of the performance of an improved street sweeper (ISS) and conventional sweepers. Dust emissions from paved roads are a major source of urban airborne particles. These emissions can be controlled by street cleaning, but commonly used sweepers were not designed for fine particle collection. A sweeper was modified to improve its ability to remove fine particles from streets and to contain its dust dispersions. Performance was measured by sampling street solids with a vacuum system before and after sweeping. Sieve analyses were made on these samples. During sampling, cascade impactor subsamples were collected to measure the finer particles. Also, dust dispersions were measured.

  9. PERFORMANCE TESTING OF THE DIPERNA SWEEPER

    EPA Science Inventory

    The DiPerna Sweeper, a partial-vacuum oil skimmer, was tested in a two-week test program conducted at the U.S. Environmental Test Tank (OHMSETT) in Leonardo, New Jersey. Forty-three oil recovery tests were run. The object of the program was to establish a range of best performanc...

  10. Fanconi Anemia Genes, of Menders and Sweepers.

    PubMed

    Campello, Silvia; Cecconi, Francesco

    2016-05-23

    Reporting recently in Cell, Sumpter et al. (2016) provide evidence that Fanconi anemia (FA) pathway genes, which are mutated in the homonymous disease and are tumor suppressors known as damaged nuclear DNA "menders," also act as intracellular sweepers in selective virophagy and mitophagy. PMID:27219059

  11. Nuclear-powered space debris sweeper

    NASA Technical Reports Server (NTRS)

    Metzger, John D.; Leclaire, Rene J., Jr.; Howe, Steven D.; Burgin, Karen C.

    1989-01-01

    Future spacecraft design will be affected by collisions with man-made debris orbiting the earth. Most of this orbital space debris comes from spent rocket stages. It is projected that the source of future debris will be the result of fragmentation of large objects through hypervelocity collisions. Orbiting spacecraft will have to be protected from hypervelocity debris in orbit. The options are to armor the spacecraft, resulting in increased mass, or actively removing the debris from orbit. An active space debris sweeper is described which will utilize momentum transfer to the debris through laser-induced ablation to alter its orbital parameters to reduce orbital lifetime with eventual entry into the earth's atmosphere where it will burn. The paper describes the concept, estimates the amount of velocity change (Delta V) that can be imparted to an object through laser-induced ablation, and investigates the use of a neutral particle beam for the momentum transfer. The space sweeper concept could also be extended to provide a collision avoidance system for the space station and satellites, or could be used for collision protection during interplanetary travel.

  12. A synchronous beam sweeper for heavy ions

    SciTech Connect

    Bogaty, J.M.

    1989-01-01

    The Argonne Tandem Linac Accelerator System (ATLAS) facility at Argonne National Laboratory provides a wide range of accelerated heavy ions from the periodic table. Frequently, the beam delivery rate of 12 MHz is too fast for the type of experiment on line. Reaction by-products from a target bombardment may have a decay interval much longer than the dead time between beam bunches. To prevent data from being corrupted by incoming ions a beam sweeper was developed which synchronously eliminates selected beam bunches to suit experimental needs. As the SWEEPER is broad band (DC to 6 MHz) beam delivery rates can be instantaneously changed. Ion beam bunches are selectively kicked out by an electrostatic dipole electrode pulsed to 2 kVDC. The system has been used for almost three years with several hundred hours of operating time logged to date. Beam bunch delivery rates of 6 MHz down to 25 kHz have been provided. Since this is a non-resonant system any beam delivery rate from 6 MHz down to zero can be set. In addition, burst modes have been used where beam is supplied in 12 MHz bursts and then shut down for a period of time set by the user. 3 figs.

  13. Determination of PM10 emission rates from street sweepers.

    PubMed

    Fitz, D R; Bumiller, K

    2000-02-01

    The use of street sweepers to clean paved roads, particularly after high-wind events, has been proposed as a PM10 control method. Using an artificial tunnel, the emission rates for several street sweepers were quantified under actual operating conditions. The tunnel was a tent enclosure, 6.1 x 4.3 x 73 m, open on both ends. PM10 concentrations were measured at the inlet and outlet while a sweeper removed sand deposited along the length. Measurements were made using a specialized low-volume filter sampler and an integrating nephelometer. The volume of air passing through the tunnel was measured by releasing an inert tracer, sulfur hexafluoride, at the inlet and measuring its concentration at the outlet. A large difference in emission rates between vacuum-type sweepers was observed, with rates varying from 5 to 100 mg m-1 swept. For the cleanest sweepers, the background rates (collected by sweeping clean pavement) were about half of the total PM10 emission rate. These background emission rates likely were from diesel exhaust; background rates for the single gasoline-powered sweeper were below detection. Particle light scattering data confirmed the filter collection results. The artificial tunnel approach would be useful in measuring total emissions from other mobile and stationary sources. PMID:10680347

  14. Parametric seeding of a microresonator optical frequency comb.

    PubMed

    Papp, Scott B; Del'Haye, Pascal; Diddams, Scott A

    2013-07-29

    We have investigated parametric seeding of a microresonator frequency comb (microcomb) by way of a pump laser with two electro-optic-modulation sidebands. We show that the pump-sideband spacing is precisely replicated throughout the microcomb's optical spectrum, and we demonstrate a record absolute line-spacing stability for microcombs of 1.6 × 10(-13) at 1 s. The spectrum of a microcomb is complex, and often non-equidistant subcombs are observed. Our results demonstrate that parametric seeding can not only control the subcombs, but can lead to the generation of a strictly equidistant microcomb spectrum. PMID:23938634

  15. Narrowband alexandrite laser injection seeded with frequency dithered diode laser

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary; Lee, H. S.; Prasad, Coorg

    1991-01-01

    Narrowband radiation is produced from a pulsed alexandrite laser when injection seeded with the output of a low power, tunable, continuous wave single mode diode laser. Injection seeded power oscillators are easier to frequency stabilize than etalon narrowed lasers, are more efficient and less prone to optical damage. AlGaAs diode lasers are available with wavelengths from 760 to 770 nm in the oxygen A band that can be used for differential absorption lidar remote sensing of atmospheric pressure and temperature. Diodes with room temperature output at 740 nm may be cooled sufficiently to emit in the water vapor absorption band at 720-730 nm for humidity remote sensing. The diode laser linewidth of 200 MHz is sufficient to seed 2 or 3 longitudinal modes of the multi-transverse mode alexandrite laser, giving the pulsed laser a bandwidth of 0.007 to 0.014/cm.

  16. The effectiveness of street sweepers in removing pollutants from road surfaces in Florida.

    PubMed

    Tobin, Graham A; Brinkmann, Robert

    2002-10-01

    To test the effectiveness of street sweepers in the sandy-surfaced, subtropical Florida Peninsula, a controlled experiment was set up to compare the effectiveness of two different sweeper types in removing sediments, heavy metals, and organic constituents from a paved surface. Both a rotary brush and a regenerative air sweeper were tested on an asphalt roadway. The results indicate that rotary brush sweepers are more effective in removing total sediment loads from roads in this type of environment. However, the chemical analyses proved somewhat inconclusive. Each sweeper was effective in removing particular chemicals off streets, but neither sweeper proved better in all categories. Nevertheless, the rotary brush sweeper was most effective in removing the total sediment load off streets and is therefore recommended for use in areas covered with coarse sediments in the local drainage basin. PMID:12403017

  17. IMPROVED STREET SWEEPERS FOR CONTROLLING URBAN INHALABLE PARTICULATE MATTER

    EPA Science Inventory

    The report gives results of an experimental program to develop design modifications that can be used to improve the ability of municipal street sweepers to remove inhalable dust particles from streets. (Dust emissions from paved roads are a major source of urban inhalable particu...

  18. Energy Reconstruction with the Sweeper Magnet Focal Plane Detector

    NASA Astrophysics Data System (ADS)

    Hitt, George; Thoennessen, Michael; Frank, Nathan; Cooper, Matt; Vander Molen, A. M.; Nett, Brian

    2002-10-01

    The Sweeper Magnet Focal Plane Detector project is a collaboration of the National High Magnetic Field Laboratory (NHMFL) at Florida State University and the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The NHMFL will construct the Sweeper Magnet, a large C-type magnet necessary for the bending of rigid nuclear beams. The NSCL will build the Focal Plane Detectors consisting of two Cathode Readout Drift Detectors (CRDCs) for taking precise position measurements and an Ion Chamber with plastic scintillators for taking ΔE and E_tot measurements. During beam experiments, the Sweeper Magnet will bend the charged fragments for detection in the Focal Plane Detector. As fragments pass through, each CRDC will measure a position where fragments impinge. This will allow experimenters to calculate a fragment's trajectory and determine where it will strike the large stopping scintillator for the E_tot measurements. In order to obtain accurate energies of the fragments, the position sensitivity of the large scintillator must be mapped. By finding a functional relationship between the position of the impinging particles and the attenuation of the light emitted by the scintillator, one can use the known position information from the CRDCs to reconstruct the energy of fragments. The position sensitivity of the large plastic scintillator as measured with a collimated, pulsed blue diode will be presented.

  19. High Neotyphodium infection frequencies in tillers and seed of infected tall fescue plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research quantified frequencies of Neotyphodium infected (E+) tillers and mature seed from field-grown E+ plants of two wild tall fescue accessions from Morocco and Sardinia, Italy. Tiller infection rates were 100% (n = 50 from 10 E+ plants/accession) for each accession and over 99% of the seed...

  20. Frequency noise in frequency swept fiber laser.

    PubMed

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-04-01

    This Letter presents a measurement of the spectral content of frequency shifted pulses generated by a lightwave synthesized frequency sweeper. We found that each pulse is shifted in frequency with very high accuracy. We also discovered that noise originating from light leaking through the acousto- optical modulators and forward propagating Brillouin scattering appear in the spectrum. PMID:23546253

  1. Absolute frequency stabilization of an injection-seeded optical parametric oscillator

    SciTech Connect

    Plusquellic, D.F.; Votava, O.; Nesbitt, D.J.

    1996-03-01

    A method is described that provides absolute frequency stabilization and calibration of the signal and idler waves generated by an injection-seeded optical parametric oscillator (OPO). The method makes use of a He{endash}Ne stabilized transfer cavity (TC) to control the frequencies of the cw sources used to seed both the pump laser and OPO cavity. The TC serves as a stable calibration source for the signal and idler waves by providing marker fringes as the seed laser is scanned. Additionally, an acoustic-optic modulator (AOM) is used to shift the OPO seed laser{close_quote}s frequency before locking it onto the TC. The sidebands of the AOM are tunable over more than one free spectral range of the TC, thereby permitting stabilization of the signal and idler waves at any frequency. A {plus_minus}25-MHz residual error in the absolute frequency stabilities of the pump, signal, and idler waves is experimentally demonstrated, which is roughly 30{percent} of the 160-MHz near-transform-limited linewidths of the signal and idler pulses. {copyright} {ital 1996 Optical Society of America.}

  2. Injection seeding of a Q-switched alexandrite laser: Study of frequency stabilization

    NASA Technical Reports Server (NTRS)

    Brown, Lamarr A.

    1992-01-01

    AlGaAs diode lasers were used to injection seed a pulsed Q-switched alexandrite laser which produces a narrowband of radiation. Injection seeding is a method for achieving linewidths of less than 500 mega-Hz in the output of the broadband, tunable solid state laser. When the laser was set at a current of 59.8 milli-A and a temperature of 14.04 C, the wavelength was 767.6 nano-m. The Q-switched alexandrite laser was injection seeded and frequency stabilization was studied. The linewidth requirement was met, but the stability requirement was not due to drifting in the feedback voltage. Improvements on injection seeding should focus on increasing the feedback voltage to the laser diode, filtering the laser diode by using temperature controlled narrowband filters, and the use of diamond (SiC) grating placed inside the alexandrite laser's resonator cavity.

  3. Effect of Finite Pulse Length and Laser Frequency Chirp on HGHG and EEHG Seeding

    SciTech Connect

    Stupakov, G.; /SLAC

    2011-11-18

    Theoretical studies of high-gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) often start from a simplified model in which the beam is assumed infinitely long and longitudinally uniform and the laser induced energy modulation is perfectly sinusoidal and of infinite duration. In such a model the resulting seed has a spectrum consisting of a collection of delta-functions (of zero width) located at the harmonics of the laser frequency. Being a useful tool for study of the seed bunching amplitudes, such a model cannot be used for realistic analysis the spectral properties of the seed. In this paper we take into account the finite duration of the laser pulse as well as some possible laser phase errors to study their effect on the spectrum of the seed.

  4. Self-seeded single-frequency laser peening method

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2009-08-11

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  5. Self-seeded single-frequency laser peening method

    DOEpatents

    DAne, C.Brent; Hackey, Lloyd A.; Harris, Fritz B.

    2012-06-26

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  6. A Study of Morbidity Pattern in Street Sweepers: A Cross-sectional Study

    PubMed Central

    Sabde, Yogesh D; Zodpey, Sanjay P

    2008-01-01

    Background: Street sweepers play an important role in maintaining the health and hygiene within the cities. This job exposes the street sweepers to a variety of risk factors such as dust, toxins and diesel exhaust pollution, which make them vulnerable to develop certain occupational diseases. Therefore, it was thought necessary to study the morbidity profile in this occupational group. Objectives: To study the prevalence of morbidities among street sweepers and comparison group. Study Design: A cross-sectional study with a comparison group. Study Setting: Nagpur Municipal Corporation, Nagpur. Subjects: The study included two groups: (1) A study group comprising 273 street sweepers. (2) A comparison group comprising 142 class IV workers working in the office buildings of Nagpur Municipal Corporation, Nagpur. Materials and Methods: A pretested proforma was used to record the necessary information such as clinical history, sociodemographic factors, findings of clinical examination and investigations performed. Results and Conclusions: The important morbidities detected among street sweepers were the following: anemia (20.5%), hypertension (9.5%), upper respiratory tract infections (URTI) (7.3%) and chronic bronchitis (5.9%). In the comparison group, important morbidities detected were the following: anemia (20.4%), hypertension (11.3%), hyperacidity (9.9%), URTI (7.0%) and refractive error (7.0%). Chronic bronchitis was detected in two subjects (1.4%) of the comparison group. The prevalence of chronic bronchitis was significantly high among street sweepers than that of subjects of the comparison group. Therefore, it is recommended that further studies with a larger sample size be undertaken to identify the factors responsible for higher prevalence of chronic bronchitis among the street sweepers. PMID:19876494

  7. Single-frequency, injection-seeded Er:YAG laser based on a bow-tie ring slave resonator

    NASA Astrophysics Data System (ADS)

    Yao, B. Q.; Deng, Yu; Dai, T. Y.; Duan, X. M.; You-Lun, Ju; Wang, Y. Z.

    2015-08-01

    A diode pumped, injection-seeded Q-switched Er:YAG laser at 1645.2 nm is demonstrated. A single frequency Er:YAG monolithic nonplanar ring oscillator (NPRO) laser emitting at 1645.24 nm with a maximum output power of 500 mW is used as a seed laser. The seed laser output is injected into a bow-tie slave laser, obtaining stable single-frequency Q-switched operation of the Er:YAG laser. The maximum single-frequency Q-switched Er:YAG laser output energy is 2.9 mJ at 100 Hz with a pulse duration of 160 ns.

  8. Wavemeter measurements of frequency stability of an injection seeded alexandrite laser for pressure and temperature lidar

    NASA Technical Reports Server (NTRS)

    Prasad, C. R.; Schwemmer, G. K.; Korb, C. L.

    1992-01-01

    The GSFC pressure-temperature lidar is a differential absorption lidar operating in the oxygen A band absorption region (760 to 770 nm), and utilizes two tunable pulsed alexandrite lasers. For obtaining temperature measurements with an accuracy of less than or = 1 K, it has been determined that the stability of the online laser frequency over a period of time corresponding to a set of measurements, 0.1 to 30 min, has to be better than +/- 0.002/cm. In addition, the requirements on laser spectral bandwidth and spectral purity are less than or = 0.02/cm and greater than or = 99.9 percent, respectively. Injection seeding with a stabilized AlGaAs diode laser was used to achieve the required frequency stability and spectral bandwidth. A high resolution Fizeau wavemeter was employed to determine the frequency stability of the pulsed alexandrite laser and determine its bandwidth, mode structure. We present the results of measurements of the frequency stability and the spectrum of the injection seeded alexandrite laser.

  9. Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes

    SciTech Connect

    Nong, Hanond Markmann, Sergej; Hekmat, Negar; Jukam, Nathan; Pal, Shovon; Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A.; Wieck, Andreas D.

    2014-09-15

    A periodically poled lithium niobate (PPLN) crystal with multiple poling periods is used to generate tunable narrow-bandwidth THz pulses for injection seeding a quantum cascade laser (QCL). We demonstrate that longitudinal modes of the quantum cascade laser close to the gain maximum can be selected or suppressed according to the seed spectrum. The QCL emission spectra obtained by electro-optic sampling from the quantum cascade laser, in the most favorable case, shows high selectivity and amplification of the longitudinal modes that overlap the frequency of the narrow-band seed. Proper selection of the narrow-band THz seed from the PPLN crystal discretely tunes the longitudinal mode emission of the quantum cascade laser. Moreover, the THz wave build-up within the laser cavity is studied as a function of the round-trip time. When the seed frequency is outside the maximum of the gain spectrum the laser emission shifts to the preferential longitudinal mode.

  10. Spectral linewidth preservation in parametric frequency combs seeded by dual pumps.

    PubMed

    Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2012-07-30

    We demonstrate new technique for generation of programmable-pitch, wideband frequency combs with low phase noise. The comb generation was achieved using cavity-less, multistage mixer driven by two tunable continuous-wave pump seeds. The approach relies on phase-correlated continuous-wave pumps in order to cancel spectral linewidth broadening inherent to parametric comb generation. Parametric combs with over 200-nm bandwidth were obtained and characterized with respect to phase noise scaling to demonstrate linewidth preservation over 100 generated tones. PMID:23038314

  11. Increasing the stearate content in seed oil of Brassica juncea by heterologous expression of MlFatB affects lipid content and germination frequency of transgenic seeds.

    PubMed

    Bhattacharya, Surajit; Sinha, Saheli; Das, Natasha; Maiti, Mrinal K

    2015-11-01

    Fatty acids from dietary lipids can impart both beneficial and harmful health effects. The compositional balance between saturated and unsaturated fatty acids plays a decisive role in maintaining the physiological harmony, proper growth and development in the human system. In case of Brassica juncea seed oil, the level of saturated fatty acid, especially desirable stearate is very much lower than the recommended value, along with a high content of nutritionally undesirable erucic acid. Therefore, in order to shift the carbon flux towards the production of stearate at the expense of erucate, the MlFatB gene encoding a FatB thioesterase from Madhuca longifolia (latifolia) was expressed heterologously in seed tissues of B. juncea. The functional MlFatB competed with the highly active endogenous BjFatA thioesterase, and the transgenic B. juncea lines showed noteworthy changes in their seed fatty acid profiles. The proportion of stearate increased up to 16-fold, constituting almost 31% of the total fatty acids along with the production of arachidic acid in significant amount (up to ∼11%). Moreover, the content of erucate was reduced up to 71% in the seed oils of transgenic lines. Although a nutritionally desirable fatty acid profile was achieved, the transgenic seeds exhibit reduction or abolition of seed germination in addition to a decrease in seed lipid content. The findings of the present study revealing the stearoyl-ACP thioesterase-mediated enhancement of the stearate content that is associated with reduced germination frequency of transgenic B. juncea seeds, may explain why no natural or induced stearate-rich Brassica has been found or developed. Furthermore, this study also suggests that the newly characterized MlFatB is a potential candidate gene for refined metabolic engineering strategy in B. juncea or other plant species for increasing stearate content in seed oil. PMID:26351151

  12. Simultaneous amplification of terahertz difference frequencies by an injection-seeded semiconductor laser amplifier at 850 nm

    NASA Technical Reports Server (NTRS)

    Matsuura, S.; Chen, P.; Blake, G. A.; Pearson, J. C.; Pickett, H. M.

    1998-01-01

    Two-frequency operation of an 850 nm semiconductor optical amplifier was achieved by simultaneously injection seeding it with two diode lasers. The two frequencies could be independently amplified without strong interference when they were separated by more than 10 GHz, and the spectral purity was preserved by the amplification process. At frequency differences below 10 GHz, unbalanced two-frequency output was observed, which can be explained by a two-mode interaction driven by the refractive index modulation at the beat frequency. The laser system is suitable for the difference-frequency generation of coherent terahertz radiation in ultra-fast photoconductors or nonlinear optical media.

  13. Simultaneous amplification of terahertz difference frequencies by an injection-seeded semiconductor laser amplifier at 850 nm.

    PubMed

    Matsuura, S; Chen, P; Blake, G A; Pearson, J C; Pickett, H M

    1998-06-01

    Two-frequency operation of an 850 nm semiconductor optical amplifier was achieved by simultaneously injection seeding it with two diode lasers. The two frequencies could be independently amplified without strong interference when they were separated by more than 10 GHz, and the spectral purity was preserved by the amplification process. At frequency differences below 10 GHz, unbalanced two-frequency output was observed, which can be explained by a two-mode interaction driven by the refractive index modulation at the beat frequency. The laser system is suitable for the difference-frequency generation of coherent terahertz radiation in ultra-fast photoconductors or nonlinear optical media. PMID:11542405

  14. Plasma sweeper to control the coupling of RF power to a magnetically confined plasma

    DOEpatents

    Motley, Robert W.; Glanz, James

    1985-01-01

    A device for coupling RF power (a plasma sweeper) from a phased waveguide array for introducing RF power to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the phased waveguide array; and a potential source coupled to the electrode for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  15. Plasma sweeper to control the coupling of RF power to a magnetically confined plasma

    SciTech Connect

    Motley, R.W.; Glanz, J.

    1985-04-16

    A device for coupling RF power (a plasma sweeper) from a phased waveguide array for introducing RF power to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the phased waveguide array; and a potential source coupled to the electrode for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  16. Single-frequency, injection-seeded Q-switched operation of resonantly pumped Er:YAG ceramic laser at 1645 nm

    NASA Astrophysics Data System (ADS)

    Ye, Qing; Gao, Chunqing; Wang, Shuo; Na, Quanxin; Shi, Yang; Wang, Qing; Gao, Mingwei; Zhang, Jian

    2016-07-01

    A single-frequency Q-switched Er:YAG polycrystalline ceramic laser is reported for the first time. The `Ramp-Hold-Fire' injection-seeding technique was employed to obtain single-frequency pulses, with an Er:YAG NPRO as a seed laser. Single-frequency laser operation was obtained with pulse energy of 4.7 mJ, pulse width of 250 ns and pulse repetition rate of 200 Hz.

  17. H{sup -} beam extraction from a cesium seeded field effect transistor based radio frequency negative hydrogen ion source

    SciTech Connect

    Ando, A.; Matsuno, T.; Funaoi, T.; Tanaka, N.; Tsumori, K.; Takeiri, Y.

    2012-02-15

    H{sup -} beam was successfully extracted from a cesium seeded ion source operated using a field effect transistor inverter power supply as a radio frequency (RF) wave source. High density hydrogen plasma more than 10{sup 19} m{sup -3} was obtained using an external type antenna with RF frequency of lower than 0.5 MHz. The source was isolated by an isolation transformer and H{sup -} ion beam was extracted from a single aperture. Acceleration current and extraction current increased with the increase of extraction voltage. Addition of a small amount of cesium vapor into the source enhanced the currents.

  18. Sweeper’s lung disease: a cross-sectional study of an overlooked illness among sweepers of Pakistan

    PubMed Central

    Anwar, Shaikh Khurshid; Mehmood, Naeem; Nasim, Nasir; Khurshid, Maryam; Khurshid, Bilal

    2013-01-01

    Background Sweepers are prone to develop chronic obstructive pulmonary disease even without tobacco smoking. Purpose To investigate roadside dust as a cause of air flow obstruction among sweepers, and the role of spirometry in its preclinical diagnosis. Material and methods One-hundred nonsmoking sweepers (aged 30–60 years) of both sexes sweeping on roads for 8–12 hours a day for the Capital Development Authority of Islamabad, Pakistan were used as study participants (Group A). One-hundred healthy nonsmokers (aged 30–60 years) in the same socioeconomic group and living in the same environment represented the nonsweeper group (Group B). After proper clinical evaluation and chest X-rays, spirometric evaluation was carried out in both groups. Comparisons were drawn between various spirometric parameters. Results Pulmonary function tests showed that the mean forced vital capacity was 78 ± 1.40 in the sweeper group (Group A) and 83 ± 0.86 in the nonsweeper group (Group B). Mean forced expiratory volume in 1 second was 66 ± 1.67 in Group A and 85 ± 0.85 in Group B (P < 0.05), a difference of 19%. The forced midexpiratory flow was 41% lower in Group A than in Group B (P < 0.0001). The pattern of pulmonary function obstruction was shown to be proportional to the duration of exposure to dust caused by sweeping. Conclusion Occupational exposure to dust leads to an obstructive pattern among sweepers. Spirometry is the simplest, noninvasive technique to detect preclinical disease. PMID:23626464

  19. Focal Plane Detector System for the MSU/FSU Sweeper Magnet

    NASA Astrophysics Data System (ADS)

    Frank, Nathan; Thoennessen, Michael; Freigang, Chris; Yurkon, John; Bazin, Daniel; Clement, Ryan; Hitt, Wes

    2002-10-01

    The study of nuclei close to, or even beyond, the neutron dripline involves the reconstruction of the decay products - the charged fragment and neutron(s) - following a break-up reaction. The National High Magnetic Field Laboratory at FSU is building a sweeper magnet, which will bend the charged particles by up to 40 degrees, separating them from the neutrons, which will be detected at zero degrees with the Modular Neutron Array (MoNA). The charged particles will be detected in a system of focal plane detectors. This system consists of two Cathode Readout Drift Chambers (CRDC's), a Frisch gridded Ion Chamber and two plastic scintillation detectors. The basic design and first test results of this detector system will be described.

  20. Generation of wideband frequency combs by continuous-wave seeding of multistage mixers with synthesized dispersion.

    PubMed

    Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2012-01-30

    We numerically and experimentally demonstrate efficient generation of an equalized optical comb with 150-nm bandwidth. The comb was generated by low-power, continuous-wave seeds, eliminating the need for pulsed laser sources. The new architecture relies on efficient creation of higher-order mixing tones in phase-matched nonlinear fiber stages separated by a linear compressor. Wideband generation was enabled by precise dispersion engineering of multiple-stage parametric mixers. PMID:22330571

  1. Self-seeded single-frequency solid-state ring laser and system using same

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2007-02-20

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  2. Frequency stabilization and transverse mode discrimination in injection-seeded unstable resonator TEA CO2 lasers

    NASA Technical Reports Server (NTRS)

    Ancellet, G. M.; Menzies, R. T.; Brothers, A. M.

    1987-01-01

    Longitudinal mode selection by injection has been demonstrated as a viable technique for TEA-CO2 lasers with pulse energies of a Joule or greater. Once reliable generation of single-longitudinal-mode (SLM) pulses is obtained, the characteristics and the causes of intrapulse frequency variation can be studied. These include the effect of the decaying plasma, the thermal gradient due to the energy dissipation associated with the laser mechanism itself, and the pressure shift of the center frequency of the laser transition. The use of the positive-branch unstable resonator as an efficient means of coupling a discharge with large spatial dimensions to an optical cavity mode introduces another concern: namely, what can be done to emphasize transverse mode discrimination in an unstable resonator cavity while maintaining high coupling efficiency. These issues are discussed in this paper, and relevant experimental results are included.

  3. High frequency plant regeneration from mature seed of elite, recalcitrant Malaysian indica rice ( Oryza sativa L.) CV. MR 219.

    PubMed

    Sivakumar, P; Law, Y S; Ho, C-L; Harikrishna, Jennifer Ann

    2010-09-01

    An efficient in vitro plant regeneration system was established for elite, recalcitrant Malaysian indica rice, Oryza sativa L. CV. MR 219 using mature seeds as explant on Murashige and Skoog and Chu N6 media containing 2,4-dichlorophenoxy acetic acid and kinetin either alone or in different combinations. L-proline, casein hydrolysate and L-glutamine were added to callus induction media for enhancement of embryogenic callus induction. The highest frequency of friable callus induction (84%) was observed in N6 medium containing 2.5 mg l(-1) 2,4-dichlorophenoxy acetic acid, 0.2 mg l(-1) kinetin, 2.5 mg l(-1) L-proline, 300 mg l(-1) casein hydrolysate, 20 mg l(-1) L-glutamine and 30 g l(-1) sucrose under culture in continuous lighting conditions. The maximum regeneration frequency (71%) was observed, when 30-day-old N6 friable calli were cultured on MS medium supplemented with 3 mg l(-1) 6-benzyl aminopurine, 1 mg l(-1) naphthalene acetic acid, 2.5 mg l(-1) L-proline, 300 mg l(-1) casein hydrolysate and 3% maltose. Developed shoots were rooted in half strength MS medium supplemented with 2% sucrose and were successfully transplanted to soil with 95% survival. This protocol may be used for other recalcitrant indica rice genotypes and to transfer desirable genes in to Malaysian indica rice cultivar MR219 for crop improvement. PMID:20724277

  4. Electrostatic Insect Sweeper for Eliminating Whiteflies Colonizing Host Plants: A Complementary Pest Control Device in An Electric Field Screen-Guarded Greenhouse

    PubMed Central

    Takikawa, Yoshihiro; Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kusakari, Shin-ichi; Okada, Kiyotsugu; Kimbara, Junji; Osamura, Kazumi; Toyoda, Hideyoshi

    2015-01-01

    Our greenhouse tomatoes have suffered from attacks by viruliferous whiteflies Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) over the last 10 years. The fundamental countermeasure was the application of an electric field screen to the greenhouse windows to prevent their entry. However, while the protection was effective, it was incomplete, because of the lack of a guard at the greenhouse entrance area; in fact, the pests entered from the entrance door when workers entered and exited. To address this, we developed a portable electrostatic insect sweeper as a supplementary technique to the screen. In this sweeper, eight insulated conductor wires (ICWs) were arranged at constant intervals along a polyvinylchloride (PVC) pipe and covered with a cylindrical stainless net. The ICWs and metal net were linked to a DC voltage generator (operated by 3-V alkaline batteries) inside the grip and oppositely electrified to generate an electric field between them. Whiteflies on the plants were attracted to the sweeper that was gently slid along the leaves. This apparatus was easy to operate on-site in a greenhouse and enabled capture of the whiteflies detected during the routine care of the tomato plants. Using this apparatus, we caught all whiteflies that invaded the non-guarded entrance door and minimized the appearance and spread of the viral disease in tomato plants in the greenhouse. PMID:26463195

  5. Electrostatic Insect Sweeper for Eliminating Whiteflies Colonizing Host Plants: A Complementary Pest Control Device in An Electric Field Screen-Guarded Greenhouse.

    PubMed

    Takikawa, Yoshihiro; Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kusakari, Shin-Ichi; Okada, Kiyotsugu; Kimbara, Junji; Osamura, Kazumi; Toyoda, Hideyoshi

    2015-01-01

    Our greenhouse tomatoes have suffered from attacks by viruliferous whiteflies Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) over the last 10 years. The fundamental countermeasure was the application of an electric field screen to the greenhouse windows to prevent their entry. However, while the protection was effective, it was incomplete, because of the lack of a guard at the greenhouse entrance area; in fact, the pests entered from the entrance door when workers entered and exited. To address this, we developed a portable electrostatic insect sweeper as a supplementary technique to the screen. In this sweeper, eight insulated conductor wires (ICWs) were arranged at constant intervals along a polyvinylchloride (PVC) pipe and covered with a cylindrical stainless net. The ICWs and metal net were linked to a DC voltage generator (operated by 3-V alkaline batteries) inside the grip and oppositely electrified to generate an electric field between them. Whiteflies on the plants were attracted to the sweeper that was gently slid along the leaves. This apparatus was easy to operate on-site in a greenhouse and enabled capture of the whiteflies detected during the routine care of the tomato plants. Using this apparatus, we caught all whiteflies that invaded the non-guarded entrance door and minimized the appearance and spread of the viral disease in tomato plants in the greenhouse. PMID:26463195

  6. Multiline short-pulse solid-state seeded carbon dioxide laser for extreme ultraviolet employing multipass radio frequency excited slab amplifier.

    PubMed

    Nowak, Krzysztof M; Ohta, Takeshi; Suganuma, Takashi; Fujimoto, Junichi; Mizoguchi, Hakaru

    2013-03-15

    In this Letter we describe in more detail a solid-state seeded, nanosecond pulse, multiline CO(2) oscillator designed and built for the extreme ultraviolet (EUV) laser-produced-plasma (LPP) source. Our oscillator featured quantum cascade laser seeders, a diffraction-type seed beam combiner, and a radio-frequency-discharge-excited, diffusion-cooled, slab-waveguide CO(2) gain cell in a compact multipass regenerative amplifier configuration. The oscillator generated pulses of exceptional stability in terms of envelope, energy, and spectrum. Excellent stability of output was achieved without any additional techniques. The output spectrum consisted of two laser lines of a 00(0)1-10(0)0 band of a CO(2) molecule, P20 and P22, with a target of four lines P18-P24. The pulse duration was electronically adjustable between 11 and 35 ns at a repetition frequency from a few hertz to hundreds of kilohertz. Electronic adjustment of the pulse duration was achieved by relative timing offsets of individual seeders, opening an avenue to a range of on-line adjustments of pulse shape and spectral content timing. The jitter-tolerant operation allows for easy synchronization with an external event, such as a droplet target in an EUV LPP source. A resistance to parasitic seeding of more than 40 dB was recorded. The oscillator produced up to 20 W of average output power at a repetition rate of 100 kHz in a near-diffraction-limited beam of M(2)<1.3 and a pointing stability below 50 μrad. PMID:23503247

  7. Isolating highly enriched populations of circulating epithelial cells and other rare cells from blood using a magnetic sweeper device

    PubMed Central

    Talasaz, AmirAli H.; Powell, Ashley A.; Huber, David E.; Berbee, James G.; Roh, Kyung-Ho; Yu, Wong; Xiao, Wenzhong; Davis, Mark M.; Pease, R. Fabian; Mindrinos, Michael N.; Jeffrey, Stefanie S.; Davis, Ronald W.

    2009-01-01

    The enumeration of rare circulating epithelial cells (CEpCs) in the peripheral blood of metastatic cancer patients has shown promise for improved cancer prognosis. Moving beyond enumeration, molecular analysis of CEpCs may provide candidate surrogate endpoints to diagnose, treat, and monitor malignancy directly from the blood samples. Thorough molecular analysis of CEpCs requires the development of new sample preparation methods that yield easily accessible and purified CEpCs for downstream biochemical assays. Here, we describe a new immunomagnetic cell separator, the MagSweeper, which gently enriches target cells and eliminates cells that are not bound to magnetic particles. The isolated cells are easily accessible and can be extracted individually based on their physical characteristics to deplete any cells nonspecifically bound to beads. We have shown that our device can process 9 mL of blood per hour and captures >50% of CEpCs as measured in spiking experiments. We have shown that the separation process does not perturb the gene expression of rare cells. To determine the efficiency of our platform in isolating CEpCs from patients, we have isolated CEpCs from all 47 tubes of 9-mL blood samples collected from 17 women with metastatic breast cancer. In contrast, we could not find any circulating epithelial cells in samples from 5 healthy donors. The isolated CEpCs are all stored individually for further molecular analysis. PMID:19234122

  8. Isolating highly enriched populations of circulating epithelial cells and other rare cells from blood using a magnetic sweeper device.

    PubMed

    Talasaz, AmirAli H; Powell, Ashley A; Huber, David E; Berbee, James G; Roh, Kyung-Ho; Yu, Wong; Xiao, Wenzhong; Davis, Mark M; Pease, R Fabian; Mindrinos, Michael N; Jeffrey, Stefanie S; Davis, Ronald W

    2009-03-10

    The enumeration of rare circulating epithelial cells (CEpCs) in the peripheral blood of metastatic cancer patients has shown promise for improved cancer prognosis. Moving beyond enumeration, molecular analysis of CEpCs may provide candidate surrogate endpoints to diagnose, treat, and monitor malignancy directly from the blood samples. Thorough molecular analysis of CEpCs requires the development of new sample preparation methods that yield easily accessible and purified CEpCs for downstream biochemical assays. Here, we describe a new immunomagnetic cell separator, the MagSweeper, which gently enriches target cells and eliminates cells that are not bound to magnetic particles. The isolated cells are easily accessible and can be extracted individually based on their physical characteristics to deplete any cells nonspecifically bound to beads. We have shown that our device can process 9 mL of blood per hour and captures >50% of CEpCs as measured in spiking experiments. We have shown that the separation process does not perturb the gene expression of rare cells. To determine the efficiency of our platform in isolating CEpCs from patients, we have isolated CEpCs from all 47 tubes of 9-mL blood samples collected from 17 women with metastatic breast cancer. In contrast, we could not find any circulating epithelial cells in samples from 5 healthy donors. The isolated CEpCs are all stored individually for further molecular analysis. PMID:19234122

  9. The alternative role of 14-3-3 zeta as a sweeper of misfolded proteins in disease conditions.

    PubMed

    Kaneko, Kiyotoshi; Hachiya, Naomi S

    2006-01-01

    Here, we propose a novel hypothesis that 14-3-3 zeta might act as a sweeper of misfolded proteins by facilitating the formation of aggregates, which are referred to as inclusion bodies. Studies on the localization of the 14-3-3 proteins in different types of inclusion bodies in the brain including neurofibrillary tangle in Alzheimer's disease, pick bodies in Pick's disease, Lewy body-like hyaline inclusions in sporadic amyotrophic lateral sclerosis, prion/florid plaques in sporadic/variant Creutzfeldt-Jakob disease, nuclear inclusions in spinocerebellar ataxia-1, and possibly Lewy bodies in Parkinson's disease suggest a close association of these diseases with 14-3-3 zeta. The highly conserved hydrophobic surface of the amphipathic groove in 14-3-3 zeta represents a general mechanism with diverse cellular proteins, and it may also allow for the molecular recognition of misfolded proteins by hydrophobic interaction in disease conditions. When the abnormal processing of misfolded proteins overwhelms the quality control systems of the cell, it is likely that 14-3-3 zeta is recruited to form deposits of protein aggregates with nonnative, misfolded proteins in order to protect the cell against toxicity. Hence, 14-3-3 zeta may be considered as an auxiliary therapeutic tool in the protein aggregation disorders. PMID:16516399

  10. The Optoelectronic Swept-Frequency Laser and Its Applications in Ranging, Three-Dimensional Imaging, and Coherent Beam Combining of Chirped-Seed Amplifiers

    NASA Astrophysics Data System (ADS)

    Vasilyev, Arseny

    electronically tuned optical sources and low-cost full-field detector arrays, completely eliminating the need for moving parts traditionally employed in 3-D imaging. We describe the basic TomICam principle, and demonstrate single-pixel TomICam ranging in a proof-of-concept experiment. We also discuss the application of compressive sensing (CS) to the TomICam platform, and perform a series of numerical simulations. These simulations show that tenfold compression is feasible in CS TomICam, which effectively improves the volume acquisition speed by a factor ten. We develop chirped-wave phase-locking techniques, and apply them to coherent beam combining (CBC) of chirped-seed amplifiers (CSAs) in a master oscillator power amplifier configuration. The precise chirp linearity of the optoelectronic SFL enables non-mechanical compensation of optical delays using acousto-optic frequency shifters, and its high chirp rate simultaneously increases the stimulated Brillouin scattering (SBS) threshold of the active fiber. We characterize a 1550 nm chirped-seed amplifier coherent-combining system. We use a chirp rate of 5*1014 Hz/sec to increase the amplifier SBS threshold threefold, when compared to a single-frequency seed. We demonstrate efficient phase-locking and electronic beam steering of two 3 W erbium-doped fiber amplifier channels, achieving temporal phase noise levels corresponding to interferometric fringe visibilities exceeding 98%.

  11. Bent crystal spectrometer for both frequency and wavenumber resolved x-ray scattering at a seeded free-electron laser

    SciTech Connect

    Zastrau, Ulf; Fletcher, Luke B.; Galtier, Eric Ch.; Gamboa, Eliseo; Glenzer, Siegfried H.; Heimann, Philipp; Nagler, Bob; Schropp, Andreas; Lee, Hae Ja; Förster, Eckhart; Marschner, Heike; Wehrhan, Ortrud

    2014-09-15

    We present a cylindrically curved GaAs x-ray spectrometer with energy resolution ΔE/E = 1.1 × 10{sup −4} and wave-number resolution of Δk/k = 3 × 10{sup −3}, allowing plasmon scattering at the resolution limits of the Linac Coherent Light Source (LCLS) x-ray free-electron laser. It spans scattering wavenumbers of 3.6 to 5.2/Å in 100 separate bins, with only 0.34% wavenumber blurring. The dispersion of 0.418 eV/13.5 μm agrees with predictions within 1.3%. The reflection homogeneity over the entire wavenumber range was measured and used to normalize the amplitude of scattering spectra. The proposed spectrometer is superior to a mosaic highly annealed pyrolytic graphite spectrometer when the energy resolution needs to be comparable to the LCLS seeded bandwidth of 1 eV and a significant range of wavenumbers must be covered in one exposure.

  12. Forming Super-Massive Black Hole Seeds under the Influence of a Nearby Anisotropic Multi-Frequency Source

    NASA Astrophysics Data System (ADS)

    Regan, John A.; Johansson, Peter H.; Wise, John H.

    2016-04-01

    The photo-dissociation of {H_2} by a nearby anisotropic source of radiation is seen as a critical component in creating an environment in which a direct collapse black hole may form. Employing radiative transfer we model the effect of multi-frequency (0.76 eV - 60 eV) radiation on a collapsing halo at high redshift. We vary both the shape of the spectrum which emits the radiation and the distance to the emitting galaxy. We use blackbody spectra with temperatures of {T = 10^4 K} and {T = 10^5 K} and a realistic stellar spectrum. We find that an optimal zone exists between 1 kpc and 4 kpc from the emitting galaxy. If the halo resides too close to the emitting galaxy the photo-ionising radiation creates a large HII region which effectively disrupts the collapsing halo, too far from the source and the radiation flux drops below the level of the expected background and the {H_2} fraction remains too high. When the emitting galaxy is initially placed between 1 kpc and 2 kpc from the collapsing halo, with a spectral shape consistent with a star-forming high redshift galaxy, then a large central core forms. The mass of the central core is between 5000 and 10000 M_{⊙}at a temperature of approximately 1000 K. This core is however surrounded by a reservoir of hotter gas at approximately 8000 K which leads to mass inflow rates of the order of ˜0.1 M_{⊙} yr-1.

  13. Study of phase coherence degradation induced by a tapered semiconductor amplifier with frequency-modulated continuous-wave and pulsed seed lasers.

    PubMed

    Qi, Xiang Hui; Yi, Lin; Ma, Qian Li; Zhou, Da Wei; Zhou, Xiao Ji; Chen, Xu Zong

    2009-08-01

    We investigate the phase coherence between a seed laser and a laser amplified by a tapered semiconductor amplifier (TSA) when the seed laser is either continuous wave (CW) or pulsed. The phase fluctuations in the time domain are employed to describe the degradation of phase coherence induced by a TSA. The amplified laser is measured to be approximately 99.98% coherent with the seed, when the CW or pulsed laser is seeded, at different supplying currents of the TSA. Furthermore, the phase coherence is measured when the seed laser is modulated. The results reveal that the phase coherence degradations induced by the TSA remain the same for a seed laser with and without modulation, when different supplying currents of the TSA are applied. PMID:19649040

  14. Seed Germination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Initiation of seed germination is a critical decision for plants. It is important for seed populations under natural conditions to spread the timing of germination of individual seeds to maximize the probability of species survival. Therefore, seeds have evolved the multiple layers of mechanisms tha...

  15. Occurrence of trends of weed seed and pathogen contaminants in bentgrass seed lots in Oregon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nearly all of the bentgrass seed grown in the United States is produced in Oregon. However, little is known about the occurrence of weed seed or pathogen propagule contaminants in bentgrass seed lots. This study was conducted to assess the diversity and frequency of occurrence of weed seeds, ergot (...

  16. High-power continuous-wave mid-infrared radiation generated by difference frequency mixing of diode-laser-seeded fiber amplifiers and its application to dual-beam spectroscopy

    NASA Technical Reports Server (NTRS)

    Lancaster, D. G.; Richter, D.; Curl, R. F.; Tittel, F. K.; Goldberg, L.; Koplow, J.

    1999-01-01

    We report the generation of up to 0.7 mW of narrow-linewidth (<60-MHz) radiation at 3.3 micrometers by difference frequency mixing of a Nd:YAG-seeded 1.6-W Yb fiber amplifier and a 1.5-micrometers diode-laser-seeded 0.6-W Er/Yb fiber amplifier in periodically poled LiNbO3. A conversion efficiency of 0.09%/W (0.47 mWW-2 cm-1) was achieved. A room-air CH4 spectrum acquired with a compact 80-m multipass cell and a dual-beam spectroscopic configuration indicates an absorption sensitivity of +/-2.8 x 10(-5) (+/-1 sigma), corresponding to a sub-parts-in-10(9) (ppb) CH4 sensitivity (0.8 ppb).

  17. Seed proteomics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seeds comprise a protective covering, a small embryonic plant, and a nutrient-storage organ. Seeds are protein-rich, and have been the subject of many mass spectrometry-based analyses. Seed storage proteins (SSP), which are transient depots for reduced nitrogen, have been studied for decades by cel...

  18. A further discussion of the factors controlling the distribution of Pt, Pd, Rh and Au in road dust, gullies, road sweeper and gully flusher sediment in the city of Sheffield, UK.

    PubMed

    Prichard, H M; Sampson, J; Jackson, M

    2009-02-15

    Forty paired road dust and gully sediments from the city of Sheffield in NE England show that high platinum, palladium and rhodium concentrations derived from catalytic converters depend on proximity to both roundabouts rather than traffic lights and to topographic lows. Road dust outside schools and control samples, further away on the same road, show that Pt, Pd and Rh concentrations are dependent on passing traffic flow rather than numbers of stopping vehicles. Highest values of Pt+Pd in road dust are 852 ppb and 694 ppb in gullies. Rh has maximum values of 113 ppb in road dust and 49 ppb in gullies. Pt and Pd values of a few ppb to just over 100 ppb occur in road dust where traffic does not stop, on roads away from junctions. Pt, Pd, Rh and Au are all picked up by road sweepers and gully flushers both with maximum values of just over 100 ppb Pt and Pd. High Au values (maximum 610 ppb in a road dust) were located on pavements, in suburbs, outside schools and in road sweepers collecting in residential areas rather than on high traffic flow roads. Stratification of Pt and Pd in gullies was not observed whereas a high Au value was recorded at the bottom of a gully suggesting gravity concentration for Au. Anomalous Pd grades of 1050 ppb in road dust from a school entrance and 2040 ppb in a street sweeper sample were recorded. These high Pd- and Au-bearing samples do not have anomalous Pt or Rh values and may be sourced from jewellery or dental fillings. However, most samples have consistent Pt/Pd ratios of about 1 and Pt/Rh values of 4 to 5 indicating a catalytic converter source. Pt and Pd are concentrated in road dust at levels well above background in all the samples, including on high and low traffic flow roads. PMID:19081605

  19. High-power frequency comb in the range of 2-2.15  μm based on a holmium fiber amplifier seeded by wavelength-shifted Raman solitons from an erbium-fiber laser.

    PubMed

    Coluccelli, Nicola; Cassinerio, Marco; Gambetta, Alessio; Laporta, Paolo; Galzerano, Gianluca

    2014-03-15

    We demonstrate a room-temperature high-power frequency comb source covering the spectral region from 2 to 2.15 μm. The source is based on a femtosecond erbium-fiber laser operating at 1.55 μm with a repetition rate of 250 MHz, wavelength-shifted up to 2.06 μm by the solitonic Raman effect, seeding a large-mode-area holmium (Ho) fiber amplifier pumped by a thulium (Tm) fiber laser emitting at 1.94 μm. The frequency comb has an integrated power of 2 W, with overall power fluctuations as low as 0.3%. The beatnote between the comb and a high-spectral-purity, single-frequency Tm-Ho laser has a linewidth of 32 kHz over 1 ms observation time, with a signal-to-noise ratio in excess of 30 dB. PMID:24690863

  20. Verticillium dahliae race 2-specific PCR reveals a high frequency of race 2 strains in commercial spinach seed lots and delineates race structure.

    PubMed

    Short, Dylan P G; Gurung, Suraj; Maruthachalam, Karunakaran; Atallah, Zahi K; Subbarao, Krishna V

    2014-07-01

    Two pathogenic races of Verticillium dahliae have been described on lettuce and tomato. Host resistance to race 1 is governed by plant immune receptors that recognize the race 1-specific fungal effector Ave1. Only partial resistance to race 2 exists in lettuce. Although polymerase chain reaction (PCR) assays are available to identify race 1, no complementary test exists to positively identify race 2, except for lengthy pathogenicity assays on host differentials. Using the genome sequences of two isolates of V. dahliae, one each from races 1 and 2, we identified potential markers and PCR primers to distinguish the two races. Several primer pairs based on polymorphisms between the races were designed and tested on reference isolates of known race. One primer pair, VdR2F-VdR2R, consistently yielded a 256-bp amplicon in all race 2 isolates exclusively. We screened DNA from 677 V. dahliae isolates, including 340 from spinach seedlots, with the above primer pair and a previously published race 1-specific primer pair. DNA from isolates that did not amplify with race 1-specific PCRs amplified with the race 2-specific primers. To validate this, two differential lines of lettuce were inoculated with 53 arbitrarily selected isolates from spinach seed and their pathogenicity and virulence were assessed in a greenhouse. The reactions of the differential cultivars strongly supported the PCR data. V. dahliae race structure was investigated in crops in coastal California and elsewhere using primers specific to the two races. All artichoke isolates from California were race 1, whereas nearly all tomato isolates were race 2. Isolates from lettuce, pepper, and strawberry from California as well as isolates from spinach seed from two of four countries comprised both races, whereas only race 2 was observed in cotton, mint, olive, and potato. This highlights the importance of identifying resistance against race 2 in different hosts. The technique developed in this study will benefit

  1. Fast optical frequency sweeping using voltage controlled oscillator driven single sideband modulation combined with injection locking.

    PubMed

    Wang, Jian; Chen, Dijun; Cai, Haiwen; Wei, Fang; Qu, Ronghui

    2015-03-23

    An ultrafast optical frequency sweeping technique for narrow linewidth lasers is reported. This technique exploits the large frequency modulation bandwidth of a wideband voltage controlled oscillator (VCO) and a high speed electro-optic dual parallel Mach-Zehnder modulator (DPMZM) which works on the state of carrier suppressed single sideband modulation(CS-SSB). Optical frequency sweeping of a narrow linewidth fiber laser with 3.85 GHz sweeping range and 80 GHz/μs tuning speed is demonstrated, which is an extremely high tuning speed for frequency sweeping of narrow linewidth lasers. In addition, injection locking technique is adopted to improve the sweeper's low optical power output and small side-mode suppression ratio (SMSR). PMID:25837048

  2. Synchronous Photoinjection Using a Frequency-Doubled Gain-Switched Fiber-Coupled Seed Laser and ErYb-Doped Fiber Amplifier

    SciTech Connect

    John Hansknecht; Benard Poelker

    2006-06-01

    Light at 1.56 um from a gain-switched fiber-coupled diode laser and ErYb-doped fiber amplifier was frequency doubled to obtain over 2W average power at 780 nm with {approx} 40ps pulses and pulse repetition rate of 499 MHz. This light was used to drive the 100kV DC high voltage GaAs photoemission gun at CEBAF at Jefferson Laboratory to produce a high average current beam (100uA) of highly spin-polarized electrons (>80%). This new drive laser system represents a significant advance over laser systems used previously, providing significantly higher power and enhanced reliability.

  3. Project SEED.

    ERIC Educational Resources Information Center

    Chemical and Engineering News, 1986

    1986-01-01

    Reports on Project SEED (Summer Educational Experience for the Disadvantaged) a project in which high school students from low-income families work in summer jobs in a variety of academic, industrial, and government research labs. The program introduces the students to career possibilities in chemistry and to the advantages of higher education.…

  4. Seed rain, soil seed bank, seed loss and regeneration of Castanopsis fargesii (Fagaceae) in a subtropical evergreen broad-leaved forest

    USGS Publications Warehouse

    Du, X.; Guo, Q.; Gao, X.; Ma, K.

    2007-01-01

    Understanding the seed rain and seed loss dynamics in the natural condition has important significance for revealing the natural regeneration mechanisms. We conducted a 3-year field observation on seed rain, seed loss and natural regeneration of Castanopsis fargesii Franch., a dominant tree species in evergreen broad-leaved forests in Dujiangyan, southwestern China. The results showed that: (1) there were marked differences in (mature) seed production between mast (733,700 seeds in 2001) and regular (51,200 and 195,600 seeds in 2002 and 2003, respectively) years for C. fargesii. (2) Most seeds were dispersed in leaf litter, humus and 0-2 cm depth soil in seed bank. (3) Frequency distributions of both DBH and height indicated that C. fargesii had a relatively stable population. (4) Seed rain, seed ground density, seed loss, and leaf fall were highly dynamic and certain quantity of seeds were preserved on the ground for a prolonged time due to predator satiation in both the mast and regular years so that the continuous presence of seed bank and seedling recruitments in situ became possible. Both longer time observations and manipulative experiments should be carried out to better understand the roles of seed dispersal and regeneration process in the ecosystem performance. ?? 2006 Elsevier B.V. All rights reserved.

  5. Analysis of the plasma sweeper

    SciTech Connect

    Glanz, J.; Motley, R.W.

    1982-09-01

    The coupling of lower hybrid waves to a plasma can be modified by placing potentials on electrodes near the mouth of a phased array. Positive potentials on the electrodes create an electric field that sweeps the plasma away at a velocity c anti E x anti B/B/sup 2/. In this paper we derive the electric field created by the applied potential from the nondivergent character of the current flow and the ion momentum equation, in which ion-neutral charge-exchange collisions are retained, and we compare the predictions with experimental data.

  6. Seed Treatment. Bulletin 760.

    ERIC Educational Resources Information Center

    Lowery, Harvey C.

    This manual gives a definition of seed treatment, the types of seeds normally treated, diseases and insects commonly associated with seeds, fungicides and insecticides used, types of equipment used for seed treatment, and information on labeling and coloring of treated seed, pesticide carriers, binders, stickers, and safety precautions. (BB)

  7. What Are Chia Seeds?

    MedlinePlus

    ... Men For Women For Seniors What Are Chia Seeds? Published February 05, 2014 Print Email When you ... number of research participants. How to Eat Chia Seeds Chia seeds can be eaten raw or prepared ...

  8. Seed health and vigor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The health of lentil and chickpea seed greatly impacts the quality of the crop stand and yield. Healthy seed has a high germination rate, is whole (free of cracks or other damage), is free from foreign matter including weed seed and has limited seedborne pathogens. The health of the seed often dep...

  9. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  10. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  11. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  12. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  13. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  14. Needs of Seeds

    ERIC Educational Resources Information Center

    Keeley, Page

    2011-01-01

    The "Needs of Seeds" formative assessment probe can be used to find out whether students recognize that seeds have needs both similar to and different from plants and other living organisms (Keeley, Eberle, and Tugel 2007). The probe reveals whether students overgeneralize the needs of seeds by assuming they have the same needs as the adult plants…

  15. Pasture seed banks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In our surveys of northeastern pastures, we found the equivalent of more than 8 million seeds per acre in the surface soil (the top four inches) from the seed bank study. These seeds came from 58 species of plants. The annual forbs (all broadleaf plants with the exception of legumes and trees) domin...

  16. Preservation of recalcitrant seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recalcitrant and intermediate seeds are not included in seed banks because of misperceptions that these efforts would be futile. Between 20 and 25% of the Earth’s angiosperm species are estimated to produce recalcitrant or intermediate seeds. These species are more prevalent in the tropics and sub...

  17. Seed Development and Germination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed is the fertilized and matured ovule of angiosperms and gymnosperms and represents a crucial stage in the life cycle of plants. Seeds of diverse plant species may display differences in size, shape and color. Despite apparent morphological variations, most mature seeds consist of three major com...

  18. Seed Proteomics"

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteomic analysis of seeds encounters some specific problems that do not impinge on analyses of other plant cells, tissues, or organs. There are anatomic considerations. Seeds comprise the seed coat, the storage organ(s), and the embryonic axis. Are these to be studied individually or as a compo...

  19. Going to Seed.

    ERIC Educational Resources Information Center

    Powell, Richard R.

    1984-01-01

    Describes a unit on seeds designed to introduce students to their scientific and nutritional uses. Unit activities are easily done, employ a variety of process skills, and can be used at various grade levels. Suggests field trips to gather seeds, seed sprouting, and making cookies out of various whole grains. (JM)

  20. Injection Seeding Of A Q-Switched Alexandrite Laser

    NASA Technical Reports Server (NTRS)

    Zukowski, Barbara J. K.; Glesne, Thomas R.; Schwemmer, Geary; Czechanski, James P.; Kay, Richard B.

    1992-01-01

    Experiment demonstrates that standing-wave, Q-switched, tunable alexandrite laser can be injection-seeded to increase stability of output frequency and significantly reduce bandwidth from 750 GHz to 180 MHz. Injecting laser acts as oscillator or master, while Q-switched laser into which ouput of seed laser injected acts as amplifier or slave.

  1. Occurrence and trends of weed seed and ergot contaminants in Oregon grown Poa pratensis and Poa trivialis seed lots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to assess the diversity and frequency of occurrence of weed seeds and sclerotia of the fungus Claviceps purpurea (ergot) in certified seed lots of P. pratensis (Kentucky bluegrass) and P. trivialis (rough bluegrass) based on purity analysis at the Oregon State University See...

  2. Postfire seeding and plant community recovery in the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As wildland fire frequency increases around the globe, increased understanding of plant community recovery in burned landscapes is needed to improve effectiveness of rehabilitation efforts. We measured establishment of seeded species, colonization of Bromus tectorum L. (cheatgrass), and recovery of ...

  3. Vehicle-based road dust emission measurement—Part II: Effect of precipitation, wintertime road sanding, and street sweepers on inferred PM 10 emission potentials from paved and unpaved roads

    NASA Astrophysics Data System (ADS)

    Kuhns, H.; Etyemezian, V.; Green, M.; Hendrickson, Karin; McGown, Michael; Barton, Kevin; Pitchford, Marc

    Testing Re-Entrained Kinetic Emissions from Roads (TRAKER) is a new technique to infer paved and unpaved road dust PM 10 emission potentials based on particulate matter (PM) measurements made onboard a moving vehicle. Light scattering instruments mounted in front and behind the vehicle's tires measure the differential particle concentration of dust suspended by the vehicle's tire in contact with the road surface. Through empirical regressions relating the differential concentration (i.e. TRAKER signal) with the vehicle speed and the downwind flux of PM 10 particles from the road, an equation is derived to infer the speed independent road dust emission potential from the measured TRAKER signal. Measurements from TRAKER offer a new perspective on the processes that affect road dust emissions. The system was used to investigate temporal changes in emission potentials from paved roads in both the winter and summer in the Treasure Valley in Southwest Idaho. During the 3-week wintertime sampling period, the residential road dust PM 10 emission potential decreased by ˜50%. Summertime PM 10 emission potentials were similar to those observed at the end of the winter sampling and showed no upward or downward trends. Wintertime unpaved road emissions increased consistently with the number of days since the last rainfall. Measurement of road dust emission potentials after road sanding on dry roads indicated a 75% increase in PM 10 emissions after 2.5 h. This effect was short lived and emission potentials returned to their pre-sanding levels within 8 h of the sand application. Street sweeping with mechanical and vacuum sweepers was found to offer no measurable reduction in PM 10 emission potentials. On several roads, the PM 10 emission potentials actually increased immediately after vacuum sweeping. Long term effects of street sweeping on road dust emissions were not evaluated as part of this study and may offer some overall reduction in PM emissions from paved roads.

  4. Hot seeding using large Y-123 seeds

    NASA Astrophysics Data System (ADS)

    Scruggs, S. J.; Putman, P. T.; Zhou, Y. X.; Fang, H.; Salama, K.

    2006-07-01

    There are several motivations for increasing the diameter of melt textured single domain discs. The maximum magnetic field produced by a trapped field magnet is proportional to the radius of the sample. Furthermore, the availability of trapped field magnets with large diameter could enable their use in applications that have traditionally been considered to require wound electromagnets, such as beam bending magnets for particle accelerators and electric propulsion. We have investigated the possibility of using large area epitaxial growth instead of the conventional point nucleation growth mechanism. This process involves the use of large Y123 seeds for the purpose of increasing the maximum achievable Y123 single domain size. The hot seeding technique using large Y-123 seeds was employed to seed Y-123 samples. Trapped field measurements indicate that single domain samples were indeed grown by this technique. Microstructural evaluation indicates that growth can be characterized by a rapid nucleation followed by the usual peritectic grain growth which occurs when large seeds are used. Critical temperature measurements show that no local Tc suppression occurs in the vicinity of the seed. This work supports the suggestion of using an iterative method for increasing the size of Y-123 single domains that can be grown.

  5. Mutational effects of space flight on Zea mays seeds

    NASA Technical Reports Server (NTRS)

    Mei, M.; Qiu, Y.; He, Y.; Bucker, H.; Yang, C. H.

    1994-01-01

    The growth and development of more than 500 Zea mays seeds flown on Long Duration Exposure Facility (LDEF) were studied. Somatic mutations, including white-yellow stripes on leaves, dwarfing, change of leaf sheath color or seedling color were observed in plants developed from these seeds. When the frequency of white-yellow formation was used as the endpoint and compared with data from ground based studies, the dose to which maize seeds might be exposed during the flight was estimated to be equivalent to 635 cGy of gamma rays. Seeds from one particular holder gave a high mutation frequency and a wide mutation spectrum. White-yellow stripes on leaves were also found in some of the inbred progenies from plants displayed somatic mutation. Electron microscopy studies showed that the damage of chloroplast development in the white-yellow stripe on leaves was similar between seeds flown on LDEF and that irradiated by accelerated heavy ions on ground.

  6. A role for seed storage proteins in Arabidopsis seed longevity

    PubMed Central

    Nguyen, Thu-Phuong; Cueff, Gwendal; Hegedus, Dwayne D; Rajjou, Loïc; Bentsink, Leónie

    2015-01-01

    Proteomics approaches have been a useful tool for determining the biological roles and functions of individual proteins and identifying the molecular mechanisms that govern seed germination, vigour and viability in response to ageing. In this work the dry seed proteome of four Arabidopsis thaliana genotypes, that carry introgression fragments at the position of seed longevity quantitative trait loci and as a result display different levels of seed longevity, was investigated. Seeds at two physiological states, after-ripened seeds that had the full germination ability and aged (stored) seeds of which the germination ability was severely reduced, were compared. Aged dry seed proteomes were markedly different from the after-ripened and reflected the seed longevity level of the four genotypes, despite the fact that dry seeds are metabolically quiescent. Results confirmed the role of antioxidant systems, notably vitamin E, and indicated that protection and maintenance of the translation machinery and energy pathways are essential for seed longevity. Moreover, a new role for seed storage proteins (SSPs) was identified in dry seeds during ageing. Cruciferins (CRUs) are the most abundant SSPs in Arabidopsis and seeds of a triple mutant for three CRU isoforms (crua crub cruc) were more sensitive to artificial ageing and their seed proteins were highly oxidized compared with wild-type seeds. These results confirm that oxidation is involved in seed deterioration and that SSPs buffer the seed from oxidative stress, thus protecting important proteins required for seed germination and seedling formation. PMID:26184996

  7. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues.

    PubMed

    Gómez-González, Susana; Ojeda, Fernando; Torres-Morales, Patricio; Palma, Jazmín E

    2016-01-01

    Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene. PMID:27438267

  8. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues

    PubMed Central

    Gómez-González, Susana; Ojeda, Fernando; Torres-Morales, Patricio; Palma, Jazmín E.

    2016-01-01

    Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene. PMID:27438267

  9. A quick SEED tutorial

    USGS Publications Warehouse

    Ringler, Adam; Evans, John R.

    2015-01-01

    A number of different government-funded seismic data centers offer free open-access data (e.g., U.S. Geological Survey, National Earthquake Information Center, the Incorporated Research Institutions for Seismology (IRIS), and Data Management System), which can be freely downloaded and shared among different members of the community (Lay, 2009). To efficiently share data, it is important that different data providers follow a common format. The Standard for the Exchange of Earthquake Data (SEED) provides one such format for storing seismic and other geophysical data. The SEED format is widely used in earthquake seismology; however, SEED and its structure can be difficult for many first-time users (ourselves included). Below is a quick tutorial that outlines the basic structure of SEED format. This write-up is in no way intended to replace the comprehensive SEED manual (Ahern et al., 2009), and instead of going into the details of any specific part of the SEED format we refer the reader to the manual for additional details. The goal of this write-up is to succinctly explain the basic structure of SEED format as well as the associated jargon, as most commonly used now, in a colloquial way so that novice users of SEED can become more familiar with the format and its application quickly. Our goal is to give the reader the necessary background so that when problems or questions about SEED format arise they will have some understanding of where they should look for more details or from where the problem might be stemming. As a secondary goal, we hope to help the reader become familiar with the SEED manual (Ahern et al., 2009), which contains detailed information about all aspects of the SEED format.

  10. Examining Children's Models of Seed.

    ERIC Educational Resources Information Center

    Jewell, Natalie

    2002-01-01

    Reports research that examines children's models of seed. Explores the conceptions held by children (N=75) of germination and seed formation. Concludes that children hold a restricted meaning for the term 'seed'. (DDR)

  11. GROWING SEEDS, TEACHER'S GUIDE.

    ERIC Educational Resources Information Center

    Elementary Science Study, Newton, MA.

    THIS TEACHER'S GUIDE IS DESIGNED FOR USE WITH AN ELEMENTARY SCIENCE STUDY UNIT, "GROWING SEEDS," IN WHICH SUCH BASIC SCIENCE SKILLS AND PROCESSES AS MEASUREMENT, OBSERVATION, AND HYPOTHESIS FORMATION ARE INTRODUCED THROUGH STUDENT ACTIVITIES INVOLVING SEEDS, GERMINATION, AND SEEDLING GROWTH. THE MATERIALS WERE DEVELOPED FOR USE IN ELEMENTARY…

  12. [Quality classification criteria of Paeonia suffruticosa seeds].

    PubMed

    Cao, Ya-yue; Zhu, Zai-biao; Guo, Qiao-sheng; Liu, Li; Wang, Chang-lin

    2015-02-01

    In order to establish the quality classification criteria of Paeonia suffruticosa seeds, thirty-one batches of P. suffruticosa seeds from different provenances were selected. The seed rooting rate, seed germination rate, seed purity, seed viability, 1,000-seed weight and moisture content were determined and analyzed through SPSS 20.0 software. Seed rooting rate, seed germination rate and seed purity were selected as the main index for classification, while 1,000-seed weight, seed viability and moisture content could be used as important references. The seed quality grading of P. suffruticosa was set as three grades. The seed quality of each grade should meet following requirements: For the first grade seeds, seed rooting rate ≥ 80%, seed germination rate ≥ 80%, seed purity ≥ 90%, seed viability ≥ 80%, 1,000-seed weight ≥ 250 g, moisture content, ≤ 10. For the second grade seeds, seed rooting rate ≥ 50%, seed germination rate ≥ 60%, seed purity ≥ 70%, seed viability ≥ 75%, 1,000-seed weight ≥ 225 g, moisture content ≤ 10. For the third grade seeds, seed rooting rate ≥ 20%, seed germination rate ≥ 45%, seed purity ≥ 60%, seed viability ≥ 45%, 1,000-seed weight ≥ 205 g, moisture content ≤ 10. The quality classification criteria of P. suffruticosa seeds have been initially established. PMID:26137680

  13. The effect of burial depth on removal of seeds of Phytolacca americana.

    SciTech Connect

    Orrock, John, L.: Damschen, Ellen, I.

    2007-04-01

    Abstract - Although burial is known to have important effects on seed predation in a variety of habitats, the role of burial depth in affecting the removal of seeds in early successional systems is poorly known. Phytolacca American (pokeweed) is a model species to examine the role of burial depth in affecting seed removal because it is common in early-successional habitats, studies suggest that seed removal is indicative of seed predation, and seed predation is related to the recruitment of mature plants. To determine how burial depth affects P. americana seed removal, 20 seeds of P. americana were buried at depths of 0, 1, or 3 cm in early-successional habitats at the Savannah River Site in South Carolina for over 6 weeks. The frequency with which seeds were encountered (as measured by the removal of at least one seed) and the proportion of seeds removed was significantly greater when seeds were on the soil surface (0 cm depth) compared to seeds that were buried 1 cm or 3 cm; there was no difference in encounter or removal between seeds at 1 cm or 3 cm. Our findings suggest that burial may have important consequences for P. americana population dynamics, because seed survival depends upon whether or not the seed is buried, and relatively shallow burial can yield large increases in seed survival. Because seed limitation is known to be an important determinant of plant community composition in early successional systems, our work suggests that burial may play an unappreciated role in the dynamics of these communities by reducing predator-mediated seed limitation.

  14. Magnetic stimulation of marigold seed

    NASA Astrophysics Data System (ADS)

    Afzal, I.; Mukhtar, K.; Qasim, M.; Basra, S. M. A.; Shahid, M.; Haq, Z.

    2012-10-01

    The effects of magnetic field treatments of French marigold seeds on germination, early seedling growth and biochemical changes of seedlings were studied under controlled conditions. For this purpose, seeds were exposed to five different magnetic seed treatments for 3 min each. Most of seed treatments resulted in improved germination speed and spread, root and shoot length, seed soluble sugars and a-amylase activity. Magnetic seed treatment with 100 mT maximally improved germination, seedling vigour and starch metabolism as compared to control and other seed treatments. In emergence experiment, higher emergence percentage (4-fold), emergence index (5-fold) and vigorous seedling growth were obtained in seeds treated with 100 mT. Overall, the enhancement of marigold seeds by magnetic seed treatment with 100 mT could be related to enhanced starch metabolism. The results suggest that magnetic field treatments of French marigold seeds have the potential to enhance germination, early growth and biochemical parameters of seedlings.

  15. Comparative Proteomic Analysis of Peanut Seed and Seed Coat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peanut (Arachis hypogaea L.) is grown extensively worldwide for its edible seed and oil. In a peanut, within the hull and encasing the cotyledon is the seed coat, which is commonly referred to within the peanut industry as the skin. The seed coat is a distinct plant structure critical for seed deve...

  16. Defoliation effects on Bromus tectorum seed production: Implications for grazing

    USGS Publications Warehouse

    Hempy-Mayer, K.; Pyke, D.A.

    2008-01-01

    Cheatgrass (Bromus tectorum L.) is an invasive annual grass that creates near-homogenous stands in areas throughout the Intermountain sagebrush steppe and challenges successful native plant restoration in these areas. A clipping experiment carried out at two cheatgrass-dominated sites in eastern Oregon (Lincoln Bench and Succor Creek) evaluated defoliation as a potential control method for cheatgrass and a seeding preparation method for native plant reseeding projects. Treatments involved clipping plants at two heights (tall = 7.6 cm, and short = 2.5 cm), two phenological stages (boot and purple), and two frequencies (once and twice), although purple-stage treatments were clipped only once. Treatments at each site were replicated in a randomized complete block design that included a control with no defoliation. End-of-season seed density (seeds??m-2) was estimated by sampling viable seeds from plants, litter, and soil of each treatment. Undipped control plants produced an average of approximately 13 000 and 20 000 seeds??m-2 at Lincoln Bench and Succor Creek, respectively. Plants clipped short at the boot stage and again 2 wk later had among the lowest mean seed densities at both sites, and were considered the most successful treatments (Lincoln Bench: F 6,45 = 47.07, P < 0.0001; Succor Creek: F6,40 = 19.60, P < 0.0001). The 95% confidence intervals for seed densities were 123-324 seeds??m-2 from the Lincoln Bench treatment, and 769-2256 seeds??m-2 from the Succor Creek treatment. Literature suggests a maximum acceptable cheatgrass seed density of approximately 330 seeds??m-2 for successful native plant restoration through reseeding. Thus, although this study helped pinpoint optimal defoliation parameters for cheatgrass control, it also called into question the potential for livestock grazing to be an effective seed-bed preparation technique in native plant reseeding projects in cheatgrass-dominated areas.

  17. Photoacoustic Study of Fungal Disease of Acai ( Euterpe oleracea) Seeds

    NASA Astrophysics Data System (ADS)

    Rezende, Denise V.; Nunes, O. A. C.; Oliveira, A. C.

    2009-10-01

    Photoacoustic spectroscopy is introduced as a promising experimental technique to investigate fungus infected Acai ( Euterpe oleracea) seeds. Photoacoustic spectra of healthy and infected Acai seeds with the fungus Colletotrichum gloeosporioides were recorded firstly in the modulation frequency range of 5Hz to 700 Hz, while keeping the wavelength of excitation radiation of a Xe arc-lamp constant, to ascertain the depth of penetration of infection within the seed and secondly, at variable wavelength (wavelength scanning) in the interval 250nm to 1,000 nm, while keeping the modulation frequency constant. In the former, the photoacoustic signal strength from the infected seed was found higher than that of the healthy one, and has been associated with the appearance of new biomolecules associated with the pathogen infection. In the latter, characteristics peaks and bands were observed in the range from 650 nm to 900 nm ascribed to organic compounds with carboxylates and amines (functional groups) forming the typical metabolic structures of the fungus.

  18. Seeds in Flight

    ERIC Educational Resources Information Center

    Martin, Willard K.

    1978-01-01

    Discussed are the seed dispersal mechanisms of six different plants: big-leaf maple, pincushion tree, tree of heaven, squirting cucumber, digger pine, and bull thistle. Elaborate color and black-and-white drawings illustrate the text. (MA)

  19. Fishing for Seeds.

    ERIC Educational Resources Information Center

    Science and Children, 2001

    2001-01-01

    Describes a method to collect seeds that are dispersed from weeds while avoiding some outdoor hazards such as rough terrain or animals. Describes a plan for creating a weed fishing pole and includes a materials list. (SAH)

  20. Tomato seeds for LDEF

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Tomato seeds are prepared for their launch aboard the Langley's Long Duration Exposure Facility. Photograph published in Winds of Change, 75th Anniversary NASA publication (page 119), by James Schultz.

  1. Grape Seed Extract

    MedlinePlus

    ... Dekker; 2005:309–325. Grape. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on June ... Grape seed ( Vitis vinifera, Vitis coignetiae ). Natural Standard Database Web site. Accessed at www.naturalstandard.com on June ...

  2. Investigation of the effect of space flight factors on chromosomes in seeds

    NASA Technical Reports Server (NTRS)

    Dubinina, L. G.

    1980-01-01

    Frequency of mutations in postflight air-dry Crepis capillaris seeds, kept for five days aboard an artificial satellite was 36.0 + or - 1.9%, vs. 19.01 + or - 1.2% for seeds in a similar ground experiment. Both groups of seeds were prepared in identical concentrations and were treated by the same mutagen. The spectrum of mutations in postflight Crepis capillaris seeds contained a large number of chromosome-type mutations and some cells showed multiple alterations. Postflight seeds not treated with mutagens had a slightly higher level of mutability.

  3. Seed rain and seed bank of third- and fifth-order streams on the western slope of the cascade range. Forest Service research paper

    SciTech Connect

    Harmon, J.M.; Franklin, J.F.

    1995-04-01

    The authors compared the composition and density of the on-site vegetation, seed bank, and seed rain of three geomorphic and successional surfaces along third- and fifth- order streams on the western slope of the Cascade Range in Oregon. The on-site vegetation generally was dominated by tree species, the seed bank by herb species, and the seed rain by tree and herb species. Seed rain density generally correspond to the successional stage of the geomorphic surface and frequency of site disturbance, with the youngest and least vegetatively stable geomorphic surfaces having the highest density of trapped viable seeds. The highest density and greatest species richness of seed germinants were found on the intermediate-aged geomorphic surfaces, which had moderate levels of disturbance.

  4. Seed coat color and seed weight contribute differential responses of targeted metabolites in soybean seeds.

    PubMed

    Lee, Jinwook; Hwang, Young-Sun; Kim, Sun Tae; Yoon, Won-Byong; Han, Won Young; Kang, In-Kyu; Choung, Myoung-Gun

    2017-01-01

    The distribution and variation of targeted metabolites in soybean seeds are affected by genetic and environmental factors. In this study, we used 192 soybean germplasm accessions collected from two provinces of Korea to elucidate the effects of seed coat color and seeds dry weight on the metabolic variation and responses of targeted metabolites. The effects of seed coat color and seeds dry weight were present in sucrose, total oligosaccharides, total carbohydrates and all measured fatty acids. The targeted metabolites were clustered within three groups. These metabolites were not only differently related to seeds dry weight, but also responded differentially to seed coat color. The inter-relationship between the targeted metabolites was highly present in the result of correlation analysis. Overall, results revealed that the targeted metabolites were diverged in relation to seed coat color and seeds dry weight within locally collected soybean seed germplasm accessions. PMID:27507473

  5. Frequency curves

    USGS Publications Warehouse

    Riggs, H.C.

    1968-01-01

    This manual describes graphical and mathematical procedures for preparing frequency curves from samples of hydrologic data. It also discusses the theory of frequency curves, compares advantages of graphical and mathematical fitting, suggests methods of describing graphically defined frequency curves analytically, and emphasizes the correct interpretations of a frequency curve.

  6. Seed Transmission of Pseudoperonospora cubensis

    PubMed Central

    Cohen, Yigal; Rubin, Avia E.; Galperin, Mariana; Ploch, Sebastian; Runge, Fabian; Thines, Marco

    2014-01-01

    Pseudoperonospora cubensis, an obligate biotrophic oomycete causing devastating foliar disease in species of the Cucurbitaceae family, was never reported in seeds or transmitted by seeds. We now show that P. cubensis occurs in fruits and seeds of downy mildew-infected plants but not in fruits or seeds of healthy plants. About 6.7% of the fruits collected during 2012–2014 have developed downy mildew when homogenized and inoculated onto detached leaves and 0.9% of the seeds collected developed downy mildew when grown to the seedling stage. This is the first report showing that P. cubensis has become seed-transmitted in cucurbits. Species-specific PCR assays showed that P. cubensis occurs in ovaries, fruit seed cavity and seed embryos of cucurbits. We propose that international trade of fruits or seeds of cucurbits might be associated with the recent global change in the population structure of P. cubensis. PMID:25329308

  7. Seeds in space experiment results

    NASA Technical Reports Server (NTRS)

    Alston, Jim A.

    1991-01-01

    Two million seeds of 120 different varieties representing 106 species, 97 genera, and 55 plant families were flown aboard the Long Duration Exposure Facility (LDEF). The seeds were housed on the space exposed experiment developed for students (SEEDS) tray in sealed canister number six and in two small vented canisters. The tray was in the F-2 position. The seeds were germinated and the germination rates and development of the resulting plants compared to the control seed that stayed in Park Seed's seed storage facility. The initial results are presented. There was a better survival rate in the sealed canister in space than in the storage facility at Park Seed. At least some of the seeds in each of the vented canisters survived the exposure to vacuum for almost six years. The number of observed apparent mutations was very low.

  8. Automated seed manipulation and planting

    NASA Technical Reports Server (NTRS)

    Garcia, Ray; Herrera, Javier; Holcomb, Scott; Kelly, Paul; Myers, Scott; Rosendo, Manny; Sivitz, Herbert; Wolsefer, Dave

    1988-01-01

    The Mechanical Division fabricated three seed separators utilizing pressure gradients to move and separate wheat seeds. These separators are called minnow buckets and use air, water, or a combination of both to generate the pressure gradient. Electrostatic fields were employed in the seed separator constructed by the Electrical Division. This separator operates by forcing a temporary electric dipole on the wheat seeds and using charged electrodes to attract and move the seeds. Seed delivery to the hydroponic growth tray is accomplished by the seed cassette. The cassette is compatible with all the seed separators, and it consists of a plastic tube threaded with millipore filter paper. During planting operations, the seeds are placed in an empty cassette. The loaded cassette is then placed in the growth tray and nutrient solution provided. The solution wets the filter paper and capillary action draws the nutrients up to feed the seeds. These seeding systems were tested and showed encouraging results. Seeds were effectively separated and the cassette can support the growth of wheat plants. Problems remaining to be investigated include improving the success of delivering the seeds to the cassette and providing adequate spacing between seeds for the electric separator.

  9. An optimised protocol to isolate high-quality genomic DNA from seed tissues streamlines the workflow to obtain direct estimates of seed dispersal distances in gymnosperms.

    PubMed

    García, C; Escribano-Ávila, G

    2016-05-01

    Genotyping of maternally derived seed tissues from georefered seeds that moved away from their source tree yield direct estimates of seed dispersal distances when the location and the genotype of the fruiting tree are available. These estimates are instrumental in forecasting the response of plant communities to drivers of global change, such as fragmentation or the expansion of invasive species. Obtaining robust assessments of seed dispersal distances requires comparing reliable multilocus genotypes of maternally derived seed tissues and fruiting trees, as previously shown for angiosperm species. However, robust estimates of seed dispersal distances based on direct methods are rare in non-model gymnosperms due to the difficulty in isolating high quality DNA from inconspicuous maternally derived seed tissues. These tissues tend to yield low DNA quantities that increase the frequency of genotyping errors. Here, we deliver a step-by-step visual protocol used to identify and isolate different seed tissues of interest for dispersal studies: embryos (2n, bi-parentally derived), seed coats (2n, maternally derived), and megagametophytes (n, maternally derived). We also provide an optimised lab protocol used to obtain multilocus genotypes from the target seed tissue. These broadly applicable protocols proved successful both in avoiding contamination among different seed tissues and providing reliable multilocus genotypes. PMID:26943162

  10. Magnetic-seeding filtration

    SciTech Connect

    Depaoli, D.

    1996-10-01

    This task will investigate the capabilities of magnetic-seeding filtration for the enhanced removal of magnetic and nonmagnetic particulates from liquids. This technology appies to a wide range of liquid wastes, including groundwater, process waters, and tank supernatant. Magnetic-seeding filtration can be used in several aspects of treatment, such as (1) removal of solids, particularly those in the colloidal-size range that are difficult to remove by conventional means; (2) removal of contaminants by precipitation processes; and (3) removal of contaminants by sorption processes.

  11. Multiple seeds sensitivity using a single seed with threshold.

    PubMed

    Egidi, Lavinia; Manzini, Giovanni

    2015-08-01

    Spaced seeds are a fundamental tool for similarity search in biosequences. The best sensitivity/selectivity trade-offs are obtained using many seeds simultaneously: This is known as the multiple seed approach. Unfortunately, spaced seeds use a large amount of memory and the available RAM is a practical limit to the number of seeds one can use simultaneously. Inspired by some recent results on lossless seeds, we revisit the approach of using a single spaced seed and considering two regions homologous if the seed hits in at least t sufficiently close positions. We show that by choosing the locations of the don't care symbols in the seed using quadratic residues modulo a prime number, we derive single seeds that when used with a threshold t > 1 have competitive sensitivity/selectivity trade-offs, indeed close to the best multiple seeds known in the literature. In addition, the choice of the threshold t can be adjusted to modify sensitivity and selectivity a posteriori, thus enabling a more accurate search in the specific instance at issue. The seeds we propose also exhibit robustness and allow flexibility in usage. PMID:25747382

  12. Fiber and seed loss from seed cotton cleaning machinery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fiber and seed loss from seed cotton cleaning equipment in cotton gins occurs, but the quantity of material lost, factors affecting fiber and seed loss, and the mechanisms that cause material loss are not well understood. Two experiments were conducted to evaluate the effects of different factors on...

  13. Diode-laser-pumped Nd:YAG laser injection seeding system

    SciTech Connect

    Schmitt, R.L.; Rahn, L.A.

    1986-03-01

    We have designed and tested a compact injection seeding system consisting of a diode-laser-pumped Nd:YAG master oscillator and a permanent-magnet Faraday isolator. With active resonator frequency stabilization, this system permits highly reliable single-axial-mode operation of a Q-switched Nd:YAG laser over a period of hours. The system is capable of injection seeding both stable and unstable resonator designs and is suitable for injection seeding commercial lasers with only minor modifications.

  14. Physical View of Cloud Seeding

    ERIC Educational Resources Information Center

    Tribus, Myron

    1970-01-01

    Reviews experimental data on various aspects of climate control. Includes a discussion of (1) the physics of cloud seeding, (2) the applications of cloud seeding, and (3) the role of statistics in the field of weather modification. Bibliography. (LC)

  15. The SEED Initiative

    ERIC Educational Resources Information Center

    Teich, Carolyn R.

    2011-01-01

    Committed to fulfilling the promise of the green economy, the American Association of Community Colleges (AACC) launched the Sustainability Education and Economic Development (SEED) initiative (www.theseedcenter.org) in October 2010. The project advances sustainability and clean energy workforce development practices at community colleges by…

  16. COFFEE SEED PHYSIOLOGY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are more than 70 species of Coffea (Rubiaceae), but only C. arabica and C. canephora are used commercially. Better understanding of seed physiology within Coffea will facilitate the incorporation of genetic traits for resistance to biotic and abiotic stresses from wild relatives into commerci...

  17. Magnetic-seeding filtration

    SciTech Connect

    DePaoli, D.W.; Tsouris, C.; Yiacoumi, Sotira

    1997-10-01

    Magnetic-seeding filtration is a technology under development for the enhanced removal of magnetic and non-magnetic particulates from liquids. This process involves the addition of a small amount of magnetic seed particles (such as naturally occurring iron oxide) to a waste suspension, followed by treatment with a magnetic filter. Non-magnetic and weakly magnetic particles are made to undergo nonhomogeneous flocculation with the seed particles, forming flocs of high magnetic susceptibility that are readily removed by a conventional high-gradient magnetic filter. This technology is applicable to a wide range of liquid wastes, including groundwater, process waters, and tank supernatants. Magnetic-seeding filtration may be used in several aspects of treatment, such as (1) removal of solids, particularly those in the colloidal size range that are difficult to remove by conventional means; (2) removal of contaminants by precipitation processes; and (3) removal of contaminants by sorption processes. Waste stream characteristics for which the technology may be applicable include (1) particle sizes ranging from relatively coarse (several microns) to colloidal particles, (2) high or low radiation levels, (3) broad-ranging flow rates, (4) low to moderate solids concentration, (5) cases requiring high decontamination factors, and (6) aqueous or non-aqueous liquids. At this point, the technology is at the bench-scale stage of development; laboratory studies and fundamental modeling are currently being employed to determine the capabilities of the process.

  18. The Seeds of Change.

    ERIC Educational Resources Information Center

    Viola, Herman J.

    1991-01-01

    Discusses "Seeds of Change," a Columbian quincentenary exhibition at the Smithsonian Institution. Describes the rapid transformation of the Americas after contact with the Europeans. Reports that the exhibit explores the destruction of the native population by disease, war, slavery, the ongoing decimation of the rain forest, and the transformation…

  19. SEED Software Annotations.

    ERIC Educational Resources Information Center

    Bethke, Dee; And Others

    This document provides a composite index of the first five sets of software annotations produced by Project SEED. The software has been indexed by title, subject area, and grade level, and it covers sets of annotations distributed in September 1986, April 1987, September 1987, November 1987, and February 1988. The date column in the index…

  20. The National SEED Project.

    ERIC Educational Resources Information Center

    Nelson, Cathy L.

    1991-01-01

    The National SEED (Seeking Educational Equity and Diversity) project on Inclusive Curriculum provides K-12 teachers an opportunity for renewal and consideration of gender-inclusive and multicultural curricula. Seminars, led from multiple perspectives, immerse participants in recent scholarship on inclusive education and model teaching strategies…

  1. Healthy food trends -- chia seeds

    MedlinePlus

    ... small as poppy seeds. They come from a plant in the mint family. Chia seeds are considered to be a "super food" by many, delivering several important nutrients in just a few calories. You can eat this nutty-flavored seed in many ways.

  2. Seeds: A Celebration of Science.

    ERIC Educational Resources Information Center

    Melton, Bob

    The Space Exposed Experiment Developed for Students (SEEDS) Project offered science classes at the 5-12 and college levels the opportunity to conduct experiments involving tomato seeds that had been space-exposed over long periods of time. SEEDS kits were complete packages obtained from the National Aeronautics and Space Administration (NASA) for…

  3. Corridors cause differential seed predation.

    SciTech Connect

    Orrock, John L.; Damschen, Ellen I.

    2005-06-01

    Orrock, John, L., and Ellen I. Damschen. 2005. Corridors cause differential seed predation. Ecol. Apps. 15(3):793-798. Abstract. Corridors that connect disjunct populations are heavily debated in conservation, largely because the effects of corridors have rarely been evaluated by replicated, large-scale studies. Using large-scale experimental landscapes, we found that, in addition to documented positive effects, corridors also have negative impacts on bird-dispersed plants by affecting seed predation, and that overall predation is a function of the seeds primary consumer (rodents or arthropods). Both large-seeded Prunus serotina and small-seeded Rubus allegheniensis experienced greater predation in connected patches. However, P. serotina experienced significantly less seed predation compared to R. allegheniensis in unconnected patches, due to decreased impacts of rodent seed predators on this large-seeded species. Viewed in light of previous evidence that corridors have beneficial impacts by increasing pollination and seed dispersal, this work demonstrates that corridors may have both positive and negative effects for the same plant species at different life stages. Moreover, these effects may differentially affect plant species within the same community: seeds primarily consumed by rodents suffer less predation in unconnected patches. By shifting the impact of rodent and arthropod seed predators, corridors constructed for plant conservation could lead to shifts in the seed bank.

  4. Frequency Combs

    NASA Astrophysics Data System (ADS)

    Hänsch, Theodor W.; Picqué, Nathalie

    Much of modern research in the field of atomic, molecular, and optical science relies on lasers, which were invented some 50 years ago and perfected in five decades of intense research and development. Today, lasers and photonic technologies impact most fields of science and they have become indispensible in our daily lives. Laser frequency combs were conceived a decade ago as tools for the precision spectroscopy of atomic hydrogen. Through the development of optical frequency comb techniques, technique a setup of the size 1 ×1 m2, good for precision measurements of any frequency, and even commercially available, has replaced the elaborate previous frequency-chain schemes for optical frequency measurements, which only worked for selected frequencies. A true revolution in optical frequency measurements has occurred, paving the way for the creation of all-optical clocks clock with a precision that might approach 10-18. A decade later, frequency combs are now common equipment in all frequency metrology-oriented laboratories. They are also becoming enabling tools for an increasing number of applications, from the calibration of astronomical spectrographs to molecular spectroscopy. This chapter first describes the principle of an optical frequency comb synthesizer. Some of the key technologies to generate such a frequency comb are then presented. Finally, a non-exhaustive overview of the growing applications is given.

  5. Linearly frequency-modulated pulsed single-frequency fiber laser at 1083 nm.

    PubMed

    Zhang, Yuanfei; Yang, Changsheng; Li, Can; Feng, Zhouming; Xu, Shanhui; Deng, Huaqiu; Yang, Zhongmin

    2016-02-22

    A linearly frequency-modulated, actively Q-switched, single-frequency ring fiber laser based on injection seeding from an ultra-short cavity is demonstrated at 1083 nm. A piezoelectric transducer is employed to obtain linearly frequency-modulating performance and over 1.05 GHz frequency-tuning range is achieved with a modulating frequency reaching tens of kilohertz. A maximum peak power of the stable output pulse is over 3.83 W during frequency-modulating process. This type of pulsed fiber laser provides a promising candidate for coherent LIDAR in the measurement of thermosphere. PMID:26906980

  6. Dispersal of Transgenes through Maize Seed Systems in Mexico

    PubMed Central

    Dyer, George A.; Serratos-Hernández, J. Antonio; Perales, Hugo R.; Gepts, Paul; Piñeyro-Nelson, Alma; Chávez, Angeles; Salinas-Arreortua, Noé; Yúnez-Naude, Antonio; Taylor, J. Edward; Alvarez-Buylla, Elena R.

    2009-01-01

    Objectives Current models of transgene dispersal focus on gene flow via pollen while neglecting seed, a vital vehicle for gene flow in centers of crop origin and diversity. We analyze the dispersal of maize transgenes via seeds in Mexico, the crop's cradle. Methods We use immunoassays (ELISA) to screen for the activity of recombinant proteins in a nationwide sample of farmer seed stocks. We estimate critical parameters of seed population dynamics using household survey data and combine these estimates with analytical results to examine presumed sources and mechanisms of dispersal. Results Recombinant proteins Cry1Ab/Ac and CP4/EPSPS were found in 3.1% and 1.8% of samples, respectively. They are most abundant in southeast Mexico but also present in the west-central region. Diffusion of seed and grain imported from the United States might explain the frequency and distribution of transgenes in west-central Mexico but not in the southeast. Conclusions Understanding the potential for transgene survival and dispersal should help design methods to regulate the diffusion of germplasm into local seed stocks. Further research is needed on the interactions between formal and informal seed systems and grain markets in centers of crop origin and diversification. PMID:19503610

  7. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  8. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  9. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  10. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  11. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  12. Tree Seed Technology Training Course: Student Outline.

    ERIC Educational Resources Information Center

    Bonner, F. T.; And Others

    This manual is intended primarily to train seed collectors, seed-plant managers, seed analysts, and nursery managers, but can serve as a resource for any training course in forest regeneration. It includes both temperate and tropical tree species of all intended uses and covers the following topics: seed biology, seed collection, seed handling,…

  13. Seed priming to alleviate salinity stress in germinating seeds.

    PubMed

    Ibrahim, Ehab A

    2016-03-15

    Salinity is one of the major abiotic stresses that affect crop production in arid and semiarid areas. Seed germination and seedling growth are the stages most sensitive to salinity. Salt stress causes adverse physiological and biochemical changes in germinating seeds. It can affect the seed germination and stand establishment through osmotic stress, ion-specific effects and oxidative stress. The salinity delays or prevents the seed germination through various factors, such as a reduction in water availability, changes in the mobilization of stored reserves and affecting the structural organization of proteins. Various techniques can improve emergence and stand establishment under salt conditions. One of the most frequently utilized is seed priming. The process of seed priming involves prior exposure to an abiotic stress, making a seed more resistant to future exposure. Seed priming stimulates the pre-germination metabolic processes and makes the seed ready for radicle protrusion. It increases the antioxidant system activity and the repair of membranes. These changes promote seed vigor during germination and emergence under salinity stress. The aim of this paper is to review the recent literature on the response of plants to seed priming under salinity stress. The mechanism of the effect of salinity on seed germination is discussed and the seed priming process is summarized. Physiological, biochemical and molecular changes induced by priming that lead to seed enhancement are covered. Plants' responses to some priming agents under salinity stress are reported based on the best available data. For a great number of crops, little information exists and further research is needed. PMID:26812088

  14. Crop protection by seed coating.

    PubMed

    Ehsanfar, S; Modarres-Sanavy, S A M

    2005-01-01

    Providence of sufficient and healthy food for increasing human population clears the importance of notice to increasing crop production in company with environmental loss reduction. Growth and yield of every plant with sexual reproduction, depends on germination & emergence of sown seeds. Seed is a small alive plant that its biological function is protection and nutrition of embryo. Biological, chemical and physiological characteristics of seed, affect on plant performance & its resistance to undesirable environmental conditions, and even on its total yield. So attention to seed and try to increase its performance is so important. One of the factors that cause reduction in germination percentage and seedling establishment, is seed disease. It's possible to control these diseases by treating the seed before planting it. Coating the seed with pesticides, is one of the ways to gain this goal. Seed coating is a technique in which several material as fertilizers, nutritional elements, moisture attractive or repulsive agents, plant growth regulators, rhizobium inocolum, chemical & pesticide etc, add to seed by adhesive agents and cause to increase seed performance and germination. Seed coating, leads to increase benefits in seed industry, because seeds can use all of their genetic vigor. This technique is used for seeds of many garden plants, valuable crops (such as corn, sunflower, canola, alfalfa,...) and some of the grasses. In this technique that was first used in coating cereal seeds in 1930, a thin and permeable layer of pesticide is stuck on seed surface and prevent damage of seedborn pathogens. This layer is melted or splited after absorption of moisture and suitable temperature by seed, and let the radical to exit the seed. In this approach materials are used accurately with seed, evaporation & leakage of pesticide and also adverse effects of some pesticides on seeds are diminished, and these factors cause to increase the accuracy and performance of pesticide

  15. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  16. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  17. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  18. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  19. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  20. Empty Seeds Are Not Always Bad: Simultaneous Effect of Seed Emptiness and Masting on Animal Seed Predation

    PubMed Central

    Perea, Ramón; Venturas, Martin; Gil, Luis

    2013-01-01

    Seed masting and production of empty seeds have often been considered independently as different strategies to reduce seed predation by animals. Here, we integrate both phenomena within the whole assemblage of seed predators (both pre and post-dispersal) and in two contrasting microsites (open vs. sheltered) to improve our understanding of the factors controlling seed predation in a wind-dispersed tree (Ulmus laevis). In years with larger crop sizes more avian seed predators were attracted with an increase in the proportion of full seeds predated on the ground. However, for abundant crops, the presence of empty seeds decreased the proportion of full seeds predated. Empty seeds remained for a very long period in the tree, making location of full seeds more difficult for pre-dispersal predators and expanding the overall seed drop period at a very low cost (in dry biomass and allocation of C, N and P). Parthenocarpy (non-fertilized seeds) was the main cause of seed emptiness whereas seed abortion was produced in low quantity. These aborted seeds fell prematurely and, thus, could not work as deceptive seeds. A proportion of 50% empty seeds significantly reduced ground seed predation by 26%. However, a high rate of parthenocarpy (beyond 50% empty seeds) did not significantly reduce seed predation in comparison to 50% empty seeds. We also found a high variability and unpredictability in the production of empty seeds, both at tree and population level, making predator deception more effective. Open areas were especially important to facilitate seed survival since rodents (the main post-dispersal predators) consumed seeds mostly under shrub cover. In elm trees parthenocarpy is a common event that might work as an adaptive strategy to reduce seed predation. Masting per se did not apparently reduce the overall proportion of seeds predated in this wind-dispersed tree, but kept great numbers of seeds unconsumed. PMID:23776503

  1. In vitro Asymbiotic Germination of Immature Seed and Formation of Protocorm by Cephalanthera falcata (Orchidaceae)

    PubMed Central

    YAMAZAKI, JUN; MIYOSHI, KAZUMITSU

    2006-01-01

    • Background and Aims Many Orchidaceous species are threatened globally by development and over-collection from their natural habitats for horticultural purposes. Artificial propagation from seeds is difficult in most terrestrial orchids native to temperate regions. Seed production is another limiting factor in the artificial propagation for these species because of the lessened probability of pollination and the destruction of fruit by insect larvae. Members of the genus Cephalanthera are distributed across Europe, Asia and North America. C. falcata is a temperate species of East Asia and an endangered species in Japan. As successful propagation from seeds of this species has never been reported, a reproducible method is described here for seed production in situ and propagation using immature seeds in asymbiotic culture in vitro. • Methods Effects of hand-pollination and bagging treatment of ovaries were examined. Young capsules were collected every 10 d from 50 d after pollination until 120 d after pollination. Immature seeds obtained from these capsules were cultured asymbiotically on modified Kano medium and ND medium. Seed viability was examined within TTC (2,3,5-triphenyl tetrazolium chloride) test solution and histological observations were made on viable seeds by paraffin embedding at each collection stage. • Key Results and Conclusions Hand-pollination followed by bagging treatment of ovaries with aluminium foil was effective for insect control during fruit development, and successfully yielded capsules. Of the capsules, 74·5 % survived to full maturity. The highest frequency (39·8 %) of seed germination was obtained with seeds harvested 70 d after pollination. The frequency declined with progress of seed maturity on the mother plant. Minimal germination was observed with seeds harvested 100 d or later after pollination. Histological observation suggests that accumulation of such substances as lignin in the inner integument surrounding the embryo

  2. Dielectric characterization of the seeds of invasive Chinese tallow tree.

    PubMed

    Fennell, Laura Picou; Boldor, Dorin

    2013-01-01

    Biofuels have the potential to replace a significant portion of the transportation needs of the USA and the world. Low-cost lipid feedstock (i.e. tallow tree seeds) can be used for production of biodiesel, but these seeds need to be dried. Microwave drying is utilized to dry various seeds and grain, but for this process to be most efficient the dielectric properties of the materials need to be known. This study presents, for the first time, the dielectric properties of the seeds of the Chinese tallow tree. The dielectric constant and dielectric loss factor were determined using a modified free-space method for different moisture contents at frequency ranges centered around 915 and 2450 MHz respectively. The dielectric constant decreased with frequency in those respective ranges, and increased linearly with increasing moisture content, from 1.96 at 0% m.c. to 2.3 at 7% m.c. at 915 MHz, and from 2.08 at 0% m.c. to 2.42 at 7.6% m.c. at 2450 MHz. The dielectric loss factor generally decreased with frequency in both frequency ranges, and increased linearly with moisture content from a low of 0.16 at 0% m.c. to 0.21 at 7.56% at 915 MHz, respectively from a low of 0.13 at 0% m.c. to 0.2 at 7.6% m.c. at 2450 MHz. These results can be used to design microwave processing operations and systems for drying of tallow tree seeds, as well as for non-destructive determination of theses seeds' moisture content. PMID:24779226

  3. Seed thioredoxin h.

    PubMed

    Hägglund, Per; Finnie, Christine; Yano, Hiroyuki; Shahpiri, Azar; Buchanan, Bob B; Henriksen, Anette; Svensson, Birte

    2016-08-01

    Thioredoxins are nearly ubiquitous disulfide reductases involved in a wide range of biochemical pathways in various biological systems, and also implicated in numerous biotechnological applications. Plants uniquely synthesize an array of thioredoxins targeted to different cell compartments, for example chloroplastic f- and m-type thioredoxins involved in regulation of the Calvin-Benson cycle. The cytosolic h-type thioredoxins act as key regulators of seed germination and are recycled by NADPH-dependent thioredoxin reductase. The present review on thioredoxin h systems in plant seeds focuses on occurrence, reaction mechanisms, specificity, target protein identification, three-dimensional structure and various applications. The aim is to provide a general background as well as an update covering the most recent findings. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock. PMID:26876537

  4. Sensitive Technique For Detecting Alignment Of Seed Laser

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    1994-01-01

    Frequency response near resonance measured. Improved technique for detection and quantification of alignment of injection-seeding laser with associated power-oscillator laser proposed. Particularly useful in indicating alignment at spectral purity greater than 98 percent because it becomes more sensitive as perfect alignment approached. In addition, implemented relatively easily, without turning on power-oscillator laser.

  5. Acute toxicity and genotoxic activity of avocado seed extract (Persea americana Mill., c.v. Hass).

    PubMed

    Padilla-Camberos, Eduardo; Martínez-Velázquez, Moisés; Flores-Fernández, José Miguel; Villanueva-Rodríguez, Socorro

    2013-01-01

    The use of vegetal extracts requires toxicological and genotoxic evaluations to establish and verify safety before being added to human cosmetic, pharmaceutical medicine, or alimentary products. Persea americana seeds have been used in traditional medicine as treatment for several diseases. In this work, the ethanolic seed extract of Persea americana was evaluated with respect to its genotoxic potential through micronucleus assay in rodents. The frequency of micronuclei in groups of animals treated with avocado seed extract showed no differences compared to the negative control (vehicle); therefore, it is considered that the avocado seed extract showed no genotoxic activity in the micronucleus test. PMID:24298206

  6. Acute Toxicity and Genotoxic Activity of Avocado Seed Extract (Persea americana Mill., c.v. Hass)

    PubMed Central

    Padilla-Camberos, Eduardo; Martínez-Velázquez, Moisés; Flores-Fernández, José Miguel; Villanueva-Rodríguez, Socorro

    2013-01-01

    The use of vegetal extracts requires toxicological and genotoxic evaluations to establish and verify safety before being added to human cosmetic, pharmaceutical medicine, or alimentary products. Persea americana seeds have been used in traditional medicine as treatment for several diseases. In this work, the ethanolic seed extract of Persea americana was evaluated with respect to its genotoxic potential through micronucleus assay in rodents. The frequency of micronuclei in groups of animals treated with avocado seed extract showed no differences compared to the negative control (vehicle); therefore, it is considered that the avocado seed extract showed no genotoxic activity in the micronucleus test. PMID:24298206

  7. Seed-to-Seed-to-Seed Growth and Development of Arabidopsis in Microgravity

    PubMed Central

    Link, Bruce M.; Busse, James S.

    2014-01-01

    Abstract Arabidopsis thaliana was grown from seed to seed wholly in microgravity on the International Space Station. Arabidopsis plants were germinated, grown, and maintained inside a growth chamber prior to returning to Earth. Some of these seeds were used in a subsequent experiment to successfully produce a second (back-to-back) generation of microgravity-grown Arabidopsis. In general, plant growth and development in microgravity proceeded similarly to those of the ground controls, which were grown in an identical chamber. Morphologically, the most striking feature of space-grown Arabidopsis was that the secondary inflorescence branches and siliques formed nearly perpendicular angles to the inflorescence stems. The branches grew out perpendicularly to the main inflorescence stem, indicating that gravity was the key determinant of branch and silique angle and that light had either no role or a secondary role in Arabidopsis branch and silique orientation. Seed protein bodies were 55% smaller in space seed than in controls, but protein assays showed only a 9% reduction in seed protein content. Germination rates for space-produced seed were 92%, indicating that the seeds developed in microgravity were healthy and viable. Gravity is not necessary for seed-to-seed growth of plants, though it plays a direct role in plant form and may influence seed reserves. Key Words: Arabidopsis—Branch—Inflorescence—Microgravity—Morphology—Seed—Space. Astrobiology 14, 866–875. PMID:25317938

  8. Seed-to-seed-to-seed growth and development of Arabidopsis in microgravity.

    PubMed

    Link, Bruce M; Busse, James S; Stankovic, Bratislav

    2014-10-01

    Arabidopsis thaliana was grown from seed to seed wholly in microgravity on the International Space Station. Arabidopsis plants were germinated, grown, and maintained inside a growth chamber prior to returning to Earth. Some of these seeds were used in a subsequent experiment to successfully produce a second (back-to-back) generation of microgravity-grown Arabidopsis. In general, plant growth and development in microgravity proceeded similarly to those of the ground controls, which were grown in an identical chamber. Morphologically, the most striking feature of space-grown Arabidopsis was that the secondary inflorescence branches and siliques formed nearly perpendicular angles to the inflorescence stems. The branches grew out perpendicularly to the main inflorescence stem, indicating that gravity was the key determinant of branch and silique angle and that light had either no role or a secondary role in Arabidopsis branch and silique orientation. Seed protein bodies were 55% smaller in space seed than in controls, but protein assays showed only a 9% reduction in seed protein content. Germination rates for space-produced seed were 92%, indicating that the seeds developed in microgravity were healthy and viable. Gravity is not necessary for seed-to-seed growth of plants, though it plays a direct role in plant form and may influence seed reserves. PMID:25317938

  9. S-SEED Simulator

    Energy Science and Technology Software Center (ESTSC)

    2008-11-21

    This code simulates the transient response of two self-electrooptic-effect devices (SEEDs) connected in series to form an S-SEED pair as used in all-optical high-speed switching. Both optical beam propagation and carrier motion is assumed to be normal to the epi plane, so the code is inherently 1D in nature. For each SEED, an optical input in W/cm**2 is specified as a function of time (usually a step function input). The signal is absorbed during amore » double pass through the intrinsic region, with a spatially-dependent absorption coefficient that is dependent on the transient local electric field. This absorption generates electron-hole pairs that then contribute to the device current, and a transient optical output is predicted. Carriers in the semiconductor layers are generated through thermal excitation or optical absorption, move under the action of diffusion and self-consistent electric fields updated at each time step by a 1D Poisson solver, and recombine at density-dependent rates. The different epi layers are independently specified by position, thickness, doping type and density, and thus space charge effects and junction capacitance are included automatically.« less

  10. Sunflower seed allergy.

    PubMed

    Ukleja-Sokołowska, Natalia; Gawrońska-Ukleja, Ewa; Żbikowska-Gotz, Magdalena; Bartuzi, Zbigniew; Sokołowski, Łukasz

    2016-09-01

    Sunflower seeds are a rare source of allergy, but several cases of occupational allergies to sunflowers have been described. Sunflower allergens on the whole, however, still await precise and systematic description. We present an interesting case of a 40-year-old male patient, admitted to hospital due to shortness of breath and urticaria, both of which appeared shortly after the patient ingested sunflower seeds. Our laryngological examination revealed swelling of the pharynx with retention of saliva and swelling of the mouth and tongue. During diagnostics, 2 months later, we found that skin prick tests were positive to mugwort pollen (12/9 mm), oranges (6/6 mm), egg protein (3/3 mm), and hazelnuts (3/3 mm). A native prick by prick test with sunflower seeds was strongly positive (8/5 mm). Elevated concentrations of specific IgE against weed mix (inc. lenscale, mugwort, ragweed) allergens (1.04 IU/mL), Artemisia vulgaris (1.36 IU/mL), and Artemisia absinthium (0.49 IU/mL) were found. An ImmunoCap ISAC test found an average level of specific IgE against mugwort pollen allergen component Art v 1 - 5,7 ISU-E, indicating an allergy to mugwort pollen and low to medium levels of specific IgE against lipid transfer proteins (LTP) found in walnuts, peanuts, mugwort pollen, and hazelnuts. Through the ISAC inhibition test we proved that sunflower seed allergen extracts contain proteins cross-reactive with patients' IgE specific to Art v 1, Art v 3, and Jug r 3. Based on our results and the clinical pattern of the disease we confirmed that the patient is allergic to mugwort pollen and that he had an anaphylactic reaction as a result of ingesting sunflower seeds. We suspected that hypersensitivity to sunflower LTP and defensin-like proteins, both cross-reactive with mugwort pollen allergens, were the main cause of the patient's anaphylactic reaction. PMID:27222528

  11. Differential seed handling by two African primates affects seed fate and establishment of large-seeded trees

    NASA Astrophysics Data System (ADS)

    Gross-Camp, Nicole D.; Kaplin, Beth A.

    2011-11-01

    We examined the influence of seed handling by two semi-terrestrial African forest primates, chimpanzees ( Pan troglodytes) and l'Hoest's monkeys ( Cercopithecus lhoesti), on the fate of large-seeded tree species in an afromontane forest. Chimpanzees and l'Hoest's monkeys dispersed eleven seed species over one year, with quantity and quality of dispersal varying through time. Primates differed in their seed handling behaviors with chimpanzees defecating large seeds (>0.5 cm) significantly more than l'Hoest's. Furthermore, they exhibited different oral-processing techniques with chimpanzees discarding wadges containing many seeds and l'Hoest's monkeys spitting single seeds. A PCA examined the relationship between microhabitat characteristics and the site where primates deposited seeds. The first two components explained almost half of the observed variation. Microhabitat characteristics associated with sites where seeds were defecated had little overlap with those characteristics describing where spit seeds arrived, suggesting that seed handling in part determines the location where seeds are deposited. We monitored a total of 552 seed depositions through time, recording seed persistence, germination, and establishment. Defecations were deposited significantly farther from an adult conspecific than orally-discarded seeds where they experienced the greatest persistence but poorest establishment. In contrast, spit seeds were deposited closest to an adult conspecific but experienced the highest seed establishment rates. We used experimental plots to examine the relationship between seed handling, deposition site, and seed fate. We found a significant difference in seed handling and fate, with undispersed seeds in whole fruits experiencing the lowest establishment rates. Seed germination differed by habitat type with open forest experiencing the highest rates of germination. Our results highlight the relationship between primate seed handling and deposition site and seed

  12. Seed size selection by olive baboons.

    PubMed

    Kunz, Britta Kerstin; Linsenmair, Karl Eduard

    2008-10-01

    Seed size is an important plant fitness trait that can influence several steps between fruiting and the establishment of a plant's offspring. Seed size varies considerably within many plant species, yet the relevance of the trait for intra-specific fruit choice by primates has received little attention. Primates may select certain seed sizes within a species for a number of reasons, e.g. to decrease indigestible seed load or increase pulp intake per fruit. Olive baboons (Papio anubis, Cercopithecidae) are known to select seed size in unripe and mature pods of Parkia biglobosa (Mimosaceae) differentially, so that pods with small seeds, and an intermediate seed number, contribute most to dispersal by baboons. We tested whether olive baboons likewise select for smaller ripe seeds within each of nine additional fruit species whose fruit pulp baboons commonly consume, and for larger seeds in one species in which baboons feed on the seeds. Species differed in fruit type and seed number per fruit. For five of these species, baboons dispersed seeds that were significantly smaller than seeds extracted manually from randomly collected fresh fruits. In contrast, for three species, baboons swallowed seeds that were significantly longer and/or wider than seeds from fresh fruits. In two species, sizes of ingested seeds and seeds from fresh fruits did not differ significantly. Baboons frequently spat out seeds of Drypetes floribunda (Euphorbiaceae) but not those of other plant species having seeds of equal size. Oral processing of D. floribunda seeds depended on seed size: seeds that were spat out were significantly larger and swallowed seeds smaller, than seeds from randomly collected fresh fruits. We argue that seed size selection in baboons is influenced, among other traits, by the amount of pulp rewarded per fruit relative to seed load, which is likely to vary with fruit and seed shape. PMID:18780144

  13. Network models of frugivory and seed dispersal: Challenges and opportunities

    NASA Astrophysics Data System (ADS)

    Carlo, Tomás A.; Yang, Suann

    2011-11-01

    Network analyses have emerged as a new tool to study frugivory and seed dispersal (FSD) mutualisms because networks can model and simplify the complexity of multiple community-wide species interactions. Moreover, network theory suggests that structural properties, such as the presence of highly generalist species, are linked to the stability of mutualistic communities. However, we still lack empirical validation of network model predictions. Here we outline new research avenues to connect network models to FSD processes, and illustrate the challenges and opportunities of this tool with a field study. We hypothesized that generalist frugivores would be important for forest stability by dispersing seeds into deforested areas and initiating reforestation. We then constructed a network of plant-frugivore interactions using published data and identified the most generalist frugivores. To test the importance of generalists we measured: 1) the frequency with which frugivores moved between pasture and forest, 2) the bird-generated seed rain under perches in the pasture, and 3) the perching frequency of birds above seed traps. The generalist frugivores in the forest network were not important for seed dispersal into pastures, and thus for forest recovery, because the forest network excluded habitat heterogeneities, frugivore behavior, and movements. More research is needed to develop ways to incorporate relevant FSD processes into network models in order for these models to be more useful to community ecology and conservation. The network framework can serve to spark and renew interest in FSD and further our understanding of plant-animal communities.

  14. The mechanical defence advantage of small seeds.

    PubMed

    Fricke, Evan C; Wright, S Joseph

    2016-08-01

    Seed size and toughness affect seed predators, and size-dependent investment in mechanical defence could affect relationships between seed size and predation. We tested how seed toughness and mechanical defence traits (tissue density and protective tissue content) are related to seed size among tropical forest species. Absolute toughness increased with seed size. However, smaller seeds had higher specific toughness both within and among species, with the smallest seeds requiring over 2000 times more energy per gram to break than the largest seeds. Investment in mechanical defence traits varied widely but independently of the toughness-mass allometry. Instead, a physical scaling relationship confers a toughness advantage on small seeds independent of selection on defence traits and without a direct cost. This scaling relationship may contribute to seed size diversity by decreasing fitness differences among large and small seeds. Allometric scaling of toughness reconciles predictions and conflicting empirical relationships between seed size and predation. PMID:27324185

  15. Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887.

    PubMed

    Anikeeva, I D; Akatov YuA; Vaulina, E N; Kostina, L N; Marenny, A M; Portman, A I; Rusin, S V; Benton, E V

    1990-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors. PMID:11537516

  16. Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Anikeeva, I. D.; Akatov, Yu. A.; Vaulina, E. N.; Kostina, L. N.; Marenny, A.; Portman, A. I.; Rusin, S. V.

    1995-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied. The seeds were located inside the satellite in an open space, protected with aluminum foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminum foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival rate and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can thus be regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

  17. Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887

    NASA Technical Reports Server (NTRS)

    Anikeeva, I. D.; Vaulina, E. N.; Kostina, L. N.; Marenny, A. M.; Portman, A. I.; Rusin, S. V.; Benton, E. V.

    1990-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

  18. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  19. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  20. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  1. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  2. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  3. Within canopy distribution of cotton seed N

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole cotton seeds can be an important component of dairy rations. Nitrogen content of the seed is an important determinant of the feed value of the seed. Efforts to increase the seed value as feed will be enhanced with knowledge of the range and distribution of seed N within the cotton crop. This s...

  4. Does seeding after wildfires in rangelands reduce erosion or invasive species?

    USGS Publications Warehouse

    Pyke, David A.; Wirth, Troy A.; Beyers, Jan L.

    2013-01-01

    Mitigation of ecological damage caused by rangeland wildfires has historically been an issue restricted to the western United States. It has focused on conservation of ecosystem function through reducing soil erosion and spread of invasive plants. Effectiveness of mitigation treatments has been debated recently. We reviewed recent literature to conduct a meta-analysis of seeding after wildfires to determine if seedings may (1) protect ecosystems against soil erosion and (2) reduce invasion or abundance of undesirable nonnative plant species. Effectiveness of postfire seedings was examined in 8 erosion and 19 invasive species cases. Seeding has little effect on erosion during the first year after fire and is highly dependent upon initial establishment and coverage of species in successive years. Among all seeding cases, 28% reduced, 67% were neutral, and 5% increased invasive species abundance. Older seedings were more likely to show reductions in invasives than younger seedings. Seedings with high plant establishment were more likely to reduce invasives than those with low establishment. Studies are needed that examine (1) frequency of adequate establishment of postfire seedings and causal factors of success or failure, (2) long-term impacts of seeding along a range of initial establishment and concomitant plant coverage over time as it relates to erosion and abundance of invasive plant species, and (3) auxiliary treatments designed to increase likelihood of germination and establishment given the inevitable variability of environmental conditions. These studies would aid land managers in deciding when postfire treatments are required and their likely level of success.

  5. New Genes in Traditional Seed Systems: Diffusion, Detectability and Persistence of Transgenes in a Maize Metapopulation

    PubMed Central

    van Heerwaarden, Joost; Ortega Del Vecchyo, Diego; Alvarez-Buylla, Elena R.; Bellon, Mauricio R.

    2012-01-01

    Gene flow of transgenes into non-target populations is an important biosafety concern. The case of genetically modified (GM) maize in Mexico has been of particular interest because of the country’s status as center of origin and landrace diversity. In contrast to maize in the U.S. and Europe, Mexican landraces form part of an evolving metapopulation in which new genes are subject to evolutionary processes of drift, gene flow and selection. Although these processes are affected by seed management and particularly seed flow, there has been little study into the population genetics of transgenes under traditional seed management. Here, we combine recently compiled data on seed management practices with a spatially explicit population genetic model to evaluate the importance of seed flow as a determinant of the long-term fate of transgenes in traditional seed systems. Seed flow between farmers leads to a much wider diffusion of transgenes than expected by pollen movement alone, but a predominance of seed replacement over seed mixing lowers the probability of detection due to a relative lack of homogenization in spatial frequencies. We find that in spite of the spatial complexities of the modeled system, persistence probabilities under positive selection are estimated quite well by existing theory. Our results have important implications concerning the feasibility of long term transgene monitoring and control in traditional seed systems. PMID:23056246

  6. Metal deposition using seed layers

    DOEpatents

    Feng, Hsein-Ping; Chen, Gang; Bo, Yu; Ren, Zhifeng; Chen, Shuo; Poudel, Bed

    2013-11-12

    Methods of forming a conductive metal layers on substrates are disclosed which employ a seed layer to enhance bonding, especially to smooth, low-roughness or hydrophobic substrates. In one aspect of the invention, the seed layer can be formed by applying nanoparticles onto a surface of the substrate; and the metallization is achieved by electroplating an electrically conducting metal onto the seed layer, whereby the nanoparticles serve as nucleation sites for metal deposition. In another approach, the seed layer can be formed by a self-assembling linker material, such as a sulfur-containing silane material.

  7. Seed mucilage from Ipomoea dasysperma.

    PubMed

    Singh, V; Pandey, M; Srivastava, A; Srivastava, V

    2007-04-01

    A non-ionic water-soluble galactomannan, having galactose and mannose in 1:6 molar ratio, was isolated from endosperm of the seeds of Ipomoea dasysperma. The seed mucilage was found to have a structure having a linear chain of beta (1-->4) linked mannopyranosyl units with D-galactose side chains attached through alpha (1-->6) linkage to the main chain. I. dasysperma seed gum possesses non-ionic characteristics of commercial seed gums and has potential to be used in food and pharmaceutical industries. PMID:17346904

  8. [Dynamics of the induced chromosomal instability in welsh onion (Allium fistulosum L.): gamma irradiation of the seeds of different storage periods].

    PubMed

    Lazarenko, L M; Bezrukov, V F

    2006-01-01

    The chromosome aberrations in root meristem cells of welsh onion (Allium fistulosum L.) seeds after gamma-irradiation (5 and 10 Gy) of different-aged seeds (7, 19, 31, 43 and 55 months of storage) were studied. The irradiation dose of 5 Gy significantly increased the frequency of aberrant anaphases (FAA) for 31- and 43-months seeds; the dose of 10 Gy significantly increased the FAA in seeds of all age groups. The irradiation of young (7 months) seeds resulted in decreasing of the fraction of bridges to the control level of the old (55-months) seeds for the dose of 5 Gy and below the control level of the old seeds--for the dose of 10 Gy. Some peculiarities of cytogenetic parameters of genome instability and the germinating capacity of the seeds made it possible to suppose that the third year of storage is a critical period for the welsh onion seeds. PMID:17100278

  9. Seed-cotton Cleaning Effects on Seed Coat Fragments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Processing problems in textile mills have been linked to seed coat fragments (SCF), so cotton ginning facilities should take steps to prevent them from forming. The objective of this experiment was to determine if the use of seed-cotton cleaners prior to the extractor-feeder/gin stand caused increa...

  10. Seed to Seed, The Secret Life of Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This is a book review of "Seed to Seed, The Secret Life of Plants", by Nicholas Harberd. The book is a diary of ruminations/introspections about plant development and about the main research topic of Nick Harberd’s laboratory. His intended audience is initially nonscientists; many of the explanation...

  11. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  12. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  13. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  14. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  15. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  16. Frequency spirals

    NASA Astrophysics Data System (ADS)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-09-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call "frequency spirals." These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  17. A guide to forest seed handling

    SciTech Connect

    Willan, R.L.

    1986-01-01

    This guide to forest seed handling focuses on seed quality, i.e., the physiological viability and vigor of the seeds. Seed and fruit development, germination, and dormancy and the fundamentals of planning seed collections are covered. The guide includes discussions on seed collection of fallen fruits or seeds from the forest floor from the crowns of felled trees, and from standing trees with access from the ground and with other means of access. Also considered are precautions to be followed during fruit and seed handling between collection and processing. The different stages in seed processing are detailed, including extraction, depulping, drying, tumbling and threshing, dewinging, cleaning, grading, and mixing. Factors affecting seed longevity in storage and the choice of storage methods are reviewed. Different forms of seed pretreatment and seed testing methods are described.

  18. Seed dormancy in Mexican teosinte

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed dormancy in wild Zea species may affect fitness and relate to ecological adaptation. The primary objective of this study was to characterize the variation in seed germination of the wild species of the genus Zea that currently grow in Mexico, and to relate this variation to their ecological zon...

  19. Differential predation of forage seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In recent field experiments we observed that the main invertebrate seed predators of overseeded tall fescue (Festuca arundinacea Schreb.) or Italian ryegrass (Lolium multiflorum Lam.) seed in unimproved pastures were harvester ants (Pogonomyrmex sp.) and common field crickets (Gryllus sp.) To determ...

  20. Chapter 3: Seed and Varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed is one of the most important factors in sugarbeet production. Seed selection is one of the most important decisions a grower can make. Without a uniform plant population of a sugarbeet variety adapted to the growing region, the producer will have difficulty achieving economical crop production....

  1. OPTIMIZING FERTILITY FOR SEED PRODUCTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed corn production is a high input and high management endeavor that yields a high value product. Most seed production fields are managed as a unit in terms of cultivars, so timing of field operations follows the same scale. However, some producers are finding that spatial variability in soil prop...

  2. Seed dormancy in alpine species

    PubMed Central

    Schwienbacher, Erich; Navarro-Cano, Jose Antonio; Neuner, Gilbert; Erschbamer, Brigitta

    2011-01-01

    In alpine species the classification of the various mechanisms underlying seed dormancy has been rather questionable and controversial. Thus, we investigated 28 alpine species to evaluate the prevailing types of dormancy. Embryo type and water impermeability of seed coats gave an indication of the potential seed dormancy class. To ascertain the actual dormancy class and level, we performed germination experiments comparing the behavior of seeds without storage, after cold-dry storage, after cold-wet storage, and scarification. We also tested the light requirement for germination in some species. Germination behavior was characterized using the final germination percentage and the mean germination time. Considering the effects of the pretreatments, a refined classification of the prevailing dormancy types was constructed based on the results of our pretreatments. Only two out of the 28 species that we evaluated had predominantly non-dormant seeds. Physiological dormancy was prevalent in 20 species, with deep physiological dormancy being the most abundant, followed by non-deep and intermediate physiological dormancy. Seeds of four species with underdeveloped embryos were assigned to the morphophysiologial dormancy class. An impermeable seed coat was identified in two species, with no additional physiological germination block. We defined these species as having physical dormancy. Light promoted the germination of seeds without storage in all but one species with physiological dormancy. In species with physical dormancy, light responses were of minor importance. We discuss our new classification in the context of former germination studies and draw implications for the timing of germination in the field. PMID:24415831

  3. Training for Certification: Seed Treatment.

    ERIC Educational Resources Information Center

    Mississippi State Univ., State College. Cooperative Extension Service.

    This Cooperative Extension Service publication from Mississippi State University is a training guide for commercial pesticide applicators. Focusing specifically on the treatment of seeds with pesticides, this publication is meant to prepare one to take the written examination for Environmental Protection Agency Seed Treatment certification.…

  4. Automated seed manipulation and planting

    NASA Technical Reports Server (NTRS)

    Garcia, Ray; Herrera, Javier; Holcomb, Scott; Kelly, Paul; Myers, Scott; Rosendo, Manny; Sivitz, Herbert; Wolsefer, Dave

    1988-01-01

    Activities for the Fall Semester, 1987 focused on investigating the mechanical/electrical properties of wheat seeds and forming various Seed Planting System (SPS) concepts based on those properties. The Electrical Division of the design group was formed to devise an SPS using electrostatic charge fields for seeding operations. Experiments concerning seed separation using electrical induction (rearranging of the charges within the seed) were conducted with promising results. The seeds, when exposed to the high voltage and low current field produced by a Van de Graff generator, were observed to move back and forth between two electrodes. An SPS concept has been developed based on this phenomena, and will be developed throughout the Spring Semester, 1988. The Mechanical Division centered on SPS concepts involving valves, pumps, and fluids to separate and deliver seeds. An SPS idea utilizing the pressure difference caused by air as it rushes out of holes drilled in the wall of a closed container has been formulated and will be considered for future development. Also, a system of seed separation and delivery employing a combination of centrifugal force, friction, and air flow was considered.

  5. Microwave drying of seed cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A small lab dryer was designed for use in drying seed cotton with components of a microwave generator mounted thereon. The magnetron emitted radiation directly into the seed cotton and a fan directed air cross-flow to the radiation direction. The microwave components were a 1.1 kW magnetron, trans...

  6. Genebanking seeds from natural populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional storage protocols have been developed to preserve genetic diversity of seeds of crops in genebanks. These same principles have been applied to preserve seeds from wild populations. While most principles for conventional storage protocols are applicable to a broad range of wild species...

  7. Insecticide seed treatments for sugarbeet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pest feeding and vectoring of viruses cause serious problems in sugarbeet production worldwide. In order to ameliorate pest and disease problems on sugarbeet, two seed treatments, Poncho Beta (60 g a.i. clothianidin + 8 g a.i. beta-cyfluthrin/100,000 seed) and Cruiser Tef (60 g a.i. thiamethoxam + 8...

  8. Physical properties of psyllium seed

    NASA Astrophysics Data System (ADS)

    Ahmadi, R.; Kalbasi-Ashtari, A.; Gharibzahedi, S.

    2012-02-01

    Physical properties ie dimensions, volume, surface area, sphericity, true density, porosity, angle of repose, terminal velocity, static and dynamic friction coefficients on plywood, stainless steel, glass and galvanized iron sheet, force required for initiating seed rupture in horizontal and vertical orientations of psyllium seed at a moisture content of 7.2% (w.b.)were determined.

  9. MAINE MUSSEL SEED CONSERVATION AREAS

    EPA Science Inventory

    SEED shows point locations of Maine mussel seed conservation areas at 1:24,000 scale. Data for this coverage were screen digitized on a 1:24000 scale base using descriptions contained in Maine Department of Marine Resources (MDMR) rules. Coastal arcs from Maine Office of GIS 1:24...

  10. Morphological Analysis of Rubus Seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Rubus exhibits morphological diversity and a wide range of reproductive systems and habitats. We examined seed coat ultrastructural morphology of seed accessions of 10 subgenera preserved at the US Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Reposito...

  11. Ripening events in seeded watermelons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seeded watermelons generally start color development in the locule (seed cavity), with color progressing to the center of the fruit during the ripening process. Soluble solids content (SSR) is thought to be highest at the blossom end. In large-fruited watermelon where only a portion of the fruit is...

  12. Frequency-shifted feedback amplifier for broadband laser cooling

    NASA Astrophysics Data System (ADS)

    Lim, Michael; van Kooy, Alexander; Yanakas, Michael

    2014-03-01

    We have developed a compact, all-solid state laser amplifier for generating asymmetric sidebands with controlled number and spacing of optical frequencies. The gain element is a tapered semiconductor amplifier, used in conjunction with an acousto-optic modulator that generates red-detuned feedback frequencies. This results in asymmetric sidebands that are all lower in optical frequency than the narrowband seed laser frequency. The output laser spectrum has a well-defined edge (the input laser frequency) and multiple sidebands whose number, frequency spacing, and power are fully controlled by the seed laser characteristics and a single radio frequency input. The number of sidebands can be varied in a controlled way, and the output optical power is variable up to the Watt level of the amplifier chip. The system will be used for broadband laser cooling.

  13. Seed Dispersal by Ants in the Semi-arid Caatinga of North-east Brazil

    PubMed Central

    Leal, Inara R.; Wirth, Rainer; Tabarelli, Marcelo

    2007-01-01

    Background and Aims Myrmecochory is a conspicuous feature of several sclerophyll ecosystems around the world but it has received little attention in the semi-arid areas of South America. This study addresses the importance of seed dispersal by ants in a 2500-km2 area of the Caatinga ecosystem (north-east Brazil) and investigates ant-derived benefits to the plant through myrmecochory. Methods Seed manipulation and dispersal by ants was investigated during a 3-year period in the Xingó region. Both plant and ant assemblages involved in seed dispersal were described and ant behaviour was characterized. True myrmecochorous seeds of seven Euphorbiaceae species (i.e. elaiosome-bearing seeds) were used in experiments designed to: (1) quantify the rates of seed cleaning/removal and the influence of both seed size and elaiosome presence on seed removal; (2) identify the fate of seeds dispersed by ants; and (3) document the benefits of seed dispersal by ants in terms of seed germination and seedling growth. Key Results Seed dispersal by ants involved one-quarter of the woody flora inhabiting the Xingó region, but true myrmecochory was restricted to 12·8 % of the woody plant species. Myrmecochorous seeds manipulated by ants faced high levels of seed removal (38–84 %) and 83 % of removed seeds were discarded on ant nests. Moreover, seed removal positively correlated with the presence of elaiosome, and elaiosome removal increased germination success by at least 30 %. Finally, some Euphorbiaceae species presented both increased germination and seedling growth on ant-nest soils. Conclusions Myrmecochory is a relevant seed dispersal mode in the Caatinga ecosystem, and is particularly frequent among Euphorbiaceae trees and shrubs. The fact that seeds reach micro-sites suitable for establishment (ant nests) supports the directed dispersal hypothesis as a possible force favouring myrmecochory in this ecosystem. Ecosystems with a high frequency of myrmecochorous plants appear not

  14. Simulation of free-electron lasers seeded with broadband radiation

    SciTech Connect

    Bajlekov, Svetoslav; Fawley, William; Schroeder, Carl; Bartolini, Riccardo; Hooker, Simon

    2011-03-10

    The longitudinal coherence of free-electron laser (FEL) radiation can be enhanced by seeding the FEL with high harmonics of an optical laser pulse. The radiation produced by high-harmonic generation (HHG), however, has a fast-varying temporal profile that can violate the slowly varying envelope approximation and limited frequency window that is employed in conventional free-electron laser simulation codes. Here we investigate the implications of violating this approximation on the accuracy of simulations. On the basis of both analytical considerations and 1D numerical studies, it is concluded that, for most realistic scenarios, conventional FEL codes are capable of accurately simulating the FEL process even when the seed radiation violates the slowly varying envelope approximation. We additionally discuss the significance of filtering the harmonic content of broadband HHG seeds.

  15. Seed biology and in vitro seed germination of Cypripedium.

    PubMed

    Zeng, Songjun; Zhang, Yu; Teixeira da Silva, Jaime A; Wu, Kunlin; Zhang, Jianxia; Duan, Jun

    2014-12-01

    Cypripedium orchids have high horticultural value. The populations of most species are very geographically restricted and they are becoming increasingly rare due to the destruction of native habitats and illegal collection. Reduction of the commercial value through large-scale propagation in vitro is a preferable option to reduce pressure from illegal collection. Cypripedium species are commercially propagated via seed germination in vitro. This review focuses on in vitro seed germination and provides an in-depth analysis of the seed biology of this genus. PMID:24191720

  16. Brassinosteroid functions in Arabidopsis seed development

    PubMed Central

    Jiang, Wen-Bo; Lin, Wen-Hui

    2013-01-01

    Seed development of flowering plant is a complicated process controlled by a signal network. Double fertilization generates 2 zygotic products (embryo and endosperm). Embryo gives rise to a daughter plant while endosperm provides nutrients for embryo during embryogenesis and germination. Seed coat differentiates from maternally derived integument and encloses embryo and endosperm. Seed size/mass and number comprise final seed yield, and seed shape also contributes to seed development and weight. Seed size is coordinated by communication among endosperm, embryo, and integument. Seed number determination is more complex to investigate and shows differencies between monocot and eudicot. Total seed number depends on sillique number and seed number per sillique in Arabidopsis. Seed comes from fertilized ovule, hence the ovule number per flower determines the maximal seed number per sillique. Early studies reported that engineering BR levels increased the yield of ovule and seed; however the molecular mechanism of BR regulation in seed development still remained unclear. Our recent studies demonstrated that BR regulated seed size, shape, and number by transcriptionally modulating specific seed developmental pathways. This review summarizes roles of BR in Arabidopsis seed development and gives clues for future application of BR in agricultural production. PMID:24270689

  17. Nectar replenishment and pollen receipt interact in their effects on seed production of Penstemon roseus.

    PubMed

    Ornelas, Juan Francisco; Lara, Carlos

    2009-07-01

    Resource supply and pollen delivery are often thought to equally limit seed production in animal-pollinated plants. At equilibrium, plants should show no response to experimental pollen supplementation because resources limit seed set above the current level of pollen attraction, while experimental reduction in pollen deposition below the equilibrium level would reduce seed set. The predicted equilibrium may be disrupted, however, if plants expend additional energy to replenish removed nectar. We investigated the combined effects of nectar removal and pollen delivery on female reproductive success of Penstemon roseus (Plantaginaceae), a hummingbird-pollinated plant that replenishes removed nectar. We first documented that the frequency of experimental nectar removal was correlated with total nectar secretion; and increased frequency of nectar removal resulted in increased female reproductive costs to the plant. Trade-offs between investing resources in nectar and investing resources in seeds were then investigated in two contrasting natural populations by removing nectar from flowers at increasing frequencies while simultaneously hand-pollinating flowers with increasing amounts of pollen. Seed set was lowest at low levels of pollen deposition, highest at medium-sized pollen loads, and intermediate when pollen loads were highest. At both sites, the frequency of nectar removal and pollen deposition had an interactive effect on seed production, in that intermediate levels of nectar removal result in the absolute highest seed set, but only at intermediate pollen loads. At high pollen loads, seed set was higher following little to no nectar removal, and at low pollen loads, all rates of nectar removal affected fecundity equally. Seed mass responded to nectar removal and pollination differently than did seed set. High levels of nectar removal and pollen delivery both lowered seed mass, with little interaction between main effects. Our findings are among the first to

  18. Why cirrus cloud seeding cannot substantially cool the planet

    NASA Astrophysics Data System (ADS)

    Gasparini, Blaž; Lohmann, Ulrike

    2016-05-01

    The net warming effect of cirrus clouds has driven part of the geoengineering research toward the idea of decreasing their occurrence frequency by seeding them with efficient ice nucleating particles. We study responses of cirrus clouds to simplified global seeding strategies in terms of their radiative fluxes with the help of the ECHAM-HAM general circulation model. Our cirrus scheme takes into account the competition between homogeneous and heterogeneous freezing, preexisting ice crystals, and the full spectrum of updraft velocities. While we find that the cirrus cloud radiative effect evaluated from our model is positive and large enough (5.7 W/m2) to confirm their geoengineering potential, none of the seeding strategies achieves a significant cooling due to complex microphysical mechanisms limiting their climatic responses. After globally uniform seeding is applied, we observe an increase in cirrus cloud cover, a decrease in ice crystal number concentration, and a decrease in ice crystal radius. An analysis of their respective radiative contributions points to the ice crystal radius decrease as the main factor limiting seeding effectiveness.

  19. Ultrahigh harmonics generation in a FEL with a seed laser

    SciTech Connect

    Goloviznin, V.V.; Amersfoort, P.W. van

    1995-12-31

    One of the most challenging problems in modern FEL technology is to operate in the X-ray region, especially in the {open_quotes}water window{close_quotes}. Because of the absence of optical resonators in this range of wavelengths, only a single-pass device may be suitable for this task. The Self-Amplified Spontaneous Emission (SASE) mechanism is now under active discussion as a realistic way to provide high-power coherent emission in the X-ray range. Both the undulator parameters and the electron beam parameters required for the lasing are achieveable at today`s technological level. On the other hand, the SASE approach implies a very long and expensive periodic magnetic structure, typically several tens of meters long. This is mainly because of the rather long build-up time necessary to establish a coherent mode from incoherent noise. A mechanism of shortening this time would be therefore highly desirable. In the present paper we consider a scheme using two undulators and a seed-laser to produce coherent X-ray emission. The first undulator and the seed-laser provide a pre-modulation of the beam while the second undulator serves as a source of coherent spontaneous radiation at a very high harmonic of the seed-laser frequency; the whole scheme may then be considered to be an FEL-based frequency upconvertor. The total length of the periodic magnetic structure is shown to be of the order of several meters, nearly an order of magnitude shorter than in the SASE case. For the same beam quality as in the SASE scheme and with realistic seed-laser parameters, the efficiency of the beam pre-modulation at the 50-th (!) harmonic is shown to be as high as 15%. The output radiation is tunable between discrete harmonics of the seed-frequency.

  20. Heat shock effects on seed germination of five Brazilian savanna species.

    PubMed

    Ribeiro, L C; Pedrosa, M; Borghetti, F

    2013-01-01

    Fire is considered an important factor in influencing the physiognomy, dynamics and composition of Neotropical savannas. Species of diverse physiognomies exhibit different responses to fire, such as population persistence and seed mortality, according to the fire frequency to which they are submitted. The aim of this study is to investigate the effects of heat shocks on seed germination of Anadenanthera macrocarpa (Benth.) Brenan, Dalbergia miscolobium Benth., Aristolochia galeata Mart. & Zucc., Kielmeyera coriacea (Spreng.) Mart. and Guazuma ulmifolia Lam., which are native species of the Brazilian savanna. The temperatures and exposure times to which the seeds were submitted were established according to data obtained in the field during a prescribed fire: 60 °C (10, 20 and 40 min), 80 °C (5, 10 and 20 min) and 100 °C (2, 5 and 10 min). Untreated seeds were used as controls. Seeds of A. galeata and K. coriacea showed high tolerance to most heat treatments, and seeds of A. macrocarpa showed a significant reduction in germination percentage after treatments of 80 °C and 100 °C. Treatments of 100 °C for 10 min reduced germination percentage for all species except G. ulmifolia, which has dormant seeds. For this species, germination was accelerated by heat treatments. The high temperatures applied did not interfere with the time to 50% germination (T(50) ) of the tolerant seeds. Seeds of the savanna species K. coriacea and A. galeata were more tolerant to heat shocks than seeds of the forest species A. macrocarpa. Guazuma ulmifolia, the forest species with seeds that germinate after heat shock, also occurs in savanna physiognomies. Overall, the high temperatures applied did not affect the germination rate of the tolerant seeds. PMID:22672775

  1. The use of certified seeds of improved wheat varieties in farms and the contributions of certified seed usage to enterprise economies: the case of Ankara province in Turkey.

    PubMed

    Tanrivermiş, Harun; Akdoğan, Ilyas

    2007-12-15

    In this research, the use of certificated seeds of improved wheat varieties in farms of Ankara, which have an important share in wheat production of Turkey and the contributions of the certified seeds usage to enterprise economy have been evaluated by using data collected from farms via a questionnaire. The low level of use of certificated wheat seed in farms is associated with many factors, such as price of the seed (cost), yield gains and suitability of the varieties for the farming aims of producers. Average productivity is 49.5% and average net profit is 39.7% higher in the production of wheat with certificated seeds of improved varieties in farms in comparison to farming with traditional varieties. Average productivity in wheat production with uncertified seeds of improved varieties is 24.9% and net profit per unit area is 24.3% higher than wheat production with traditional varieties. The net economic benefit of wheat production using certificated seeds of improved varieties and that of wheat farming with uncertified seeds has been estimated at $ 102.40 and $ 62.70 ha(-1), respectively. Some $ 6.4 benefit is generated in return for $ 1 of expense in wheat farming with certificated seeds of improved varieties instead of traditional varieties. In the absence of state subsidies for certificated seeds the use of uncertified seeds seems to be advantageous for producers. While the amount of subsidy per hectare will be a minimum of $ 101 for certificated seeds per hectare of planting area (as technological improvement), the support will be encouraging for usage of certified seeds. Many variables, such as farm size, use of certified seeds, topography of land, production system, education level and frequency of visiting the agriculture organizations of the producers influence the level of gross profit per unit area in wheat farming. Low level of use of certificated seed in farms decreases the economic benefit of new varieties which are developed as a result of long

  2. Flowering, Capsule and Seed Characteristics in Cuphea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We modeled the flowering and capsule set dynamics, quantified the level of variation in seed characteristics, elucidated the inter-relationships among seed and capsule physical dimensions, and quantified their impact on single seed weight as the main determinant of seed yield in the indeterminate, p...

  3. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  4. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  5. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  6. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  7. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  8. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at 15..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED...

  9. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at 15..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED...

  10. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at 15..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED...

  11. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at 15..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED...

  12. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at 15..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED...

  13. INTESPECIIC DIFFERENCES IN GRASS SEED IMBIBITION

    EPA Science Inventory

    Seeds from 12 grass species were studied relative to mode of wetting and time of exposure to water to document interspecific differences in imbibition characteristics. Imbibition causes seeds to become wet, and wet seeds are more detectable to consumers than dry seeds. Thus, ge...

  14. Materials used for Seed Storage Containers: Response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efficient seed storage is a shared concern among the growing number of seed banks established for crop improvement or ex situ conservation. Container properties greatly affect seed interactions with the environment and the overall cost and success of seed banking operations. Several material proper...

  15. Evaluation of Lettuce Genotypes for Seed Thermotolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermoinhibition of lettuce (Lactuca sativa L.) seed germination is a common problem associated with lettuce production. Depending on lettuce cultivars, seed germination may be inhibited when temperatures exceed 28oC. The delay or inhibition of seed germination at high temperatures may reduce seedli...

  16. 46 CFR 148.310 - Seed cake.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Seed cake. 148.310 Section 148.310 Shipping COAST GUARD... SPECIAL HANDLING Special Requirements for Certain Materials § 148.310 Seed cake. (a) This part does not apply to solvent-extracted rape seed meal, pellets, soya bean meal, cotton seed meal, or sunflower...

  17. 46 CFR 148.310 - Seed cake.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Seed cake. 148.310 Section 148.310 Shipping COAST GUARD... SPECIAL HANDLING Special Requirements for Certain Materials § 148.310 Seed cake. (a) This part does not apply to solvent-extracted rape seed meal, pellets, soya bean meal, cotton seed meal, or sunflower...

  18. 46 CFR 148.310 - Seed cake.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Seed cake. 148.310 Section 148.310 Shipping COAST GUARD... SPECIAL HANDLING Special Requirements for Certain Materials § 148.310 Seed cake. (a) This part does not apply to solvent-extracted rape seed meal, pellets, soya bean meal, cotton seed meal, or sunflower...

  19. Inheritance of seed color in Capsicum.

    PubMed

    Zewdie, Y; Bosland, P W

    2003-01-01

    The mode of seed color inheritance in Capsicum was studied via an interspecific hybridization between C. pubescens Ruiz and Pav. (black seed color) and C. eximium Hunz. (yellow seed color). Black seed color was dominant over yellow seed color. The F(2) segregation pattern showed continuous variation. The generation means analysis indicated the presence of a significant effect of additive [d], dominance [h], and additive x additive [i] interaction for seed color inheritance. The estimate for a minimum number of effective factors (genes) involved in seed color inheritance was approximately 3. PMID:12920108

  20. Seeding for pervasively overlapping communities

    NASA Astrophysics Data System (ADS)

    Lee, Conrad; Reid, Fergal; McDaid, Aaron; Hurley, Neil

    2011-06-01

    In some social and biological networks, the majority of nodes belong to multiple communities. It has recently been shown that a number of the algorithms specifically designed to detect overlapping communities do not perform well in such highly overlapping settings. Here, we consider one class of these algorithms, those which optimize a local fitness measure, typically by using a greedy heuristic to expand a seed into a community. We perform synthetic benchmarks which indicate that an appropriate seeding strategy becomes more important as the extent of community overlap increases. We find that distinct cliques provide the best seeds. We find further support for this seeding strategy with benchmarks on a Facebook network and the yeast interactome.

  1. Synthetic clonal reproduction through seeds.

    PubMed

    Marimuthu, Mohan P A; Jolivet, Sylvie; Ravi, Maruthachalam; Pereira, Lucie; Davda, Jayeshkumar N; Cromer, Laurence; Wang, Lili; Nogué, Fabien; Chan, Simon W L; Siddiqi, Imran; Mercier, Raphaël

    2011-02-18

    Cloning through seeds has potential revolutionary applications in agriculture, because it would allow vigorous hybrids to be propagated indefinitely. However, asexual seed formation or apomixis, avoiding meiosis and fertilization, is not found in the major food crops. To develop de novo synthesis of apomixis, we crossed Arabidopsis MiMe and dyad mutants that produce diploid clonal gametes to a strain whose chromosomes are engineered to be eliminated after fertilization. Up to 34% of the progeny were clones of their parent, demonstrating the conversion of clonal female or male gametes into seeds. We also show that first-generation cloned plants can be cloned again. Clonal reproduction through seeds can therefore be achieved in a sexual plant by manipulating two to four conserved genes. PMID:21330535

  2. Biotechnology of oil seed crops

    SciTech Connect

    James, A.T.

    1985-02-01

    A general summary of possibilities and limitation application of biotechnology processes to processing and/or production of fats and oils is presented. Enzymatic processes, cloning of premium perennial oil crops and genetic manipulation of oil seed compositions are discussed.

  3. Diamond Synthesis Employing Nanoparticle Seeds

    NASA Technical Reports Server (NTRS)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  4. Self-seeding of a pulsed double-grating Ti:sapphire laser oscillator

    SciTech Connect

    Tamura, Koji

    2008-04-01

    A self-seeded pulsed double-grating Ti:sapphire laser oscillator consisting of a grazing incidence cavity geometry with a pair of gratings and a standing-wave cavity pumped by a frequency-doubled Nd:YAG laser was developed and characterized. With self-seeding, narrow-linewidth single-longitudinal-mode (SLM) operation and SLM scanning were possible with a reduced lasing threshold, which was desirable for the intended applications.

  5. Effects of prolonged exposure to space flight factors for 175 days on lettuce seeds

    NASA Astrophysics Data System (ADS)

    Nevzgodina, L. V.; Maximova, E. N.; Akatov, Yu. A.

    We have studied the effects of prolonged (up to 175 days) exposure of Lactuca sativa seeds to space flight factors, including primary cosmic radiation heavy ions. The data obtained evidence a significant fourfold increase ofs pontaneous mutagenesis in seeds both with regard to the total number of aberrant cells as well as the formation of single cells with multiple aberrations. Comparison of the present experiment with earlier works shows that the frequency of such aberrations increases with the duration of the flight.

  6. Effects of prolonged exposure to space flight factors for 175 days on lettuce seeds

    SciTech Connect

    Nevzgodina, L.V.; Maximova, E.N.; Akatov, Yu.A.

    1981-01-01

    The effects of prolonged (up to 175 days) exposure of Lactuca sativa seeds to space flight factors, including primary cosmic radiation heavy ions have been studied. The data obtained evidence a significant fourfold increase of spontaneous mutagenesis in seeds both with regard to the total number of aberrant cells as well as the formation of single cells with multiple aberrations. Comparison of the present experiment with earlier works shows that the frequency of such aberrations increases with the duration of the flight.

  7. Depth Profiles in Maize ( Zea mays L.) Seeds Studied by Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hernández-Aguilar, C.; Domínguez-Pacheco, A.; Cruz-Orea, A.; Zepeda-Bautista, R.

    2015-06-01

    Photoacoustic spectroscopy (PAS) has been used to analyze agricultural seeds and can be applied to the study of seed depth profiles of these complex samples composed of different structures. The sample depth profile can be obtained through the photoacoustic (PA) signal, amplitude, and phase at different light modulation frequencies. The PA signal phase is more sensitive to changes of thermal properties in layered samples than the PA signal amplitude. Hence, the PA signal phase can also be used to characterize layers at different depths. Thus, the objective of the present study was to obtain the optical absorption spectra of maize seeds ( Zea mays L.) by means of PAS at different light modulation frequencies (17 Hz, 30 Hz, and 50 Hz) and comparing these spectra with the ones obtained from the phase-resolved method in order to separate the optical absorption spectra of seed pericarp and endosperm. The results suggest the possibility of using the phase-resolved method to obtain optical absorption spectra of different seed structures, at different depths, without damaging the seed. Thus, PAS could be a nondestructive method for characterization of agricultural seeds and thus improve quality control in the food industry.

  8. Diode-laser-pumped Nd:YAG laser injection seeding system.

    PubMed

    Schmitt, R L; Rahn, L A

    1986-03-01

    We have designed and tested a compact injection seeding system consisting of a diode-laser-pumped Nd:YAG master oscillator and a permanent-magnet Faraday isolator. With active resonator frequency stabilization, this system permits highly reliable single-axial-mode operation of a Q-switched Nd:YAG laser over a period of hours. The system is capable of injection seeding both stable and unstable resonator designs and is suitable for injection seeding commercial lasers with only minor modifications. PMID:18231224

  9. Optimum harvest maturity for Leymus chinensis seed

    PubMed Central

    Lin, Jixiang; Wang, Yingnan; Qi, Mingming; Li, Xiaoyu; Yang, Chunxue; Wang, Yongcui

    2016-01-01

    ABSTRACT Timely harvest is critical to achieve maximum seed viability and vigour in agricultural production. However, little information exists concerning how to reap the best quality seeds of Leymus chinensis, which is the dominant and most promising grass species in the Songnen Grassland of Northern China. The objective of this study was to investigate and evaluate possible quality indices of the seeds at different days after peak anthesis. Seed quality at different development stages was assessed by the colours of the seed and lemmas, seed weight, moisture content, electrical conductivity of seed leachate and germination indices. Two consecutive years of experimental results showed that the maximum seed quality was recorded at 39 days after peak anthesis. At this date, the colours of the seed and lemmas reached heavy brown and yellow, respectively. The seed weight was highest and the moisture content and the electrical conductivity of seed leachate were lowest. In addition, the seed also reached its maximum germination percentage and energy at this stage, determined using a standard germination test (SGT) and accelerated ageing test (AAT). Thus, Leymus chinensis can be harvested at 39 days after peak anthesis based on the changes in parameters. Colour identification can be used as an additional indicator to provide a more rapid and reliable measure of optimum seed maturity; approximately 10 days after the colour of the lemmas reached yellow and the colour of the seed reached heavy brown, the seed of this species was suitable for harvest. PMID:27170257

  10. Optimum harvest maturity for Leymus chinensis seed.

    PubMed

    Lin, Jixiang; Wang, Yingnan; Qi, Mingming; Li, Xiaoyu; Yang, Chunxue; Wang, Yongcui; Mu, Chunsheng

    2016-01-01

    Timely harvest is critical to achieve maximum seed viability and vigour in agricultural production. However, little information exists concerning how to reap the best quality seeds of Leymus chinensis, which is the dominant and most promising grass species in the Songnen Grassland of Northern China. The objective of this study was to investigate and evaluate possible quality indices of the seeds at different days after peak anthesis. Seed quality at different development stages was assessed by the colours of the seed and lemmas, seed weight, moisture content, electrical conductivity of seed leachate and germination indices. Two consecutive years of experimental results showed that the maximum seed quality was recorded at 39 days after peak anthesis. At this date, the colours of the seed and lemmas reached heavy brown and yellow, respectively. The seed weight was highest and the moisture content and the electrical conductivity of seed leachate were lowest. In addition, the seed also reached its maximum germination percentage and energy at this stage, determined using a standard germination test (SGT) and accelerated ageing test (AAT). Thus, Leymus chinensis can be harvested at 39 days after peak anthesis based on the changes in parameters. Colour identification can be used as an additional indicator to provide a more rapid and reliable measure of optimum seed maturity; approximately 10 days after the colour of the lemmas reached yellow and the colour of the seed reached heavy brown, the seed of this species was suitable for harvest. PMID:27170257

  11. Generation of Flat Optical Frequency Comb based on Mach-Zehnder Modulator and Recirculating Frequency Shifter Loop

    NASA Astrophysics Data System (ADS)

    Wu, Shibao; Li, Yulong; Fei, Yue; Hu, Faze

    2014-06-01

    We propose a novel scheme to generate optical frequency comb by using Mach-Zehnder modulator and recirculating frequency shifter loop based on IQ modulator driven by radio frequency clock signals. A system of 4 flat and stable comb lines generation based on Mach-Zehnder modulator is set as the seed light source of the recirculating loop. Through theorical analysis and simulation it is shown that the proposed theoretical model is proved in good agreement with simulation results.

  12. Echo-Enabled Harmonic Generation for Seeded FELs

    SciTech Connect

    Stupakov, G.; /SLAC

    2011-05-19

    In the x-ray wavelengths, the two leading FEL concepts are the self-amplified spontaneous emission (SASE) configuration and the high-gain harmonic generation (HGHG) scheme. While the radiation from a SASE FEL is coherent transversely, it typically has rather limited temporal coherence. Alternatively, the HGHG scheme allows generation of fully coherent radiation by up-converting the frequency of a high-power seed laser. However, due to the relatively low up-frequency conversion efficiency, multiple stages of HGHG FEL are needed in order to generate x-rays from a UV laser. The up-frequency conversion efficiency can be greatly improved with the recently proposed echo-enabled harmonic generation (EEHG) technique. In this work we will present the concept of EEHG, and address some practically important issues that affect the performance of the seeding. We show how the EEHG can be incorporated in the FEL scheme and what is the expected performance of the EEHG seeded FEL. We will then briefly describe the first proof-of-principle EEHG experiment carried out at the Next Linear Collider Test Accelerator (NLCTA) at SLAC. We will also discuss latest advances in the echo-scheme approach, and refer to subsequent modifications of the original concept.

  13. A Theoretical and Experimental Analysis of SBS Suppression Through Modification of Amplifier Seed

    NASA Astrophysics Data System (ADS)

    Zeringue, Clint Matthew

    2011-12-01

    Theoretical and experimental investigations of stimulated Brillouin scattering (SBS) are conducted in Yb-doped fiber amplifiers when the amplifier is simultaneously seeded with multiple distinct frequencies or with a phase modulated signal. To this end, detailed models of the SBS process are developed consisting of both a steady-state approach described mathematically by a coupled set of ordinary differential equations and also transient effects described by a coupled set of partial differential equations. For the multi-frequency seeded case, the equations are solved in the steady-state limit and include the effects of four-wave mixing (FWM), intrinsic and external thermal gradients, and laser gain. In one configuration of the multi-seeded case, the signals are separated at twice the acoustic frequency of the fiber medium in order to create nonlinear Brillouin gain coupling between the seeds and Stokes signals, which suppresses the SBS process in the highest frequency seed. The concept is theoretically investigated for the two and three seeded cases. It is shown that for this scheme, FWM becomes quite significant making this concept unlikely in a practical application requiring single-frequency output. Alternatively, a novel concept is developed to suppress SBS in fiber amplifiers that relies on laser gain competition among multiple seeds to create both a favorable thermal gradient and a reduced effective length for the SBS process. In one configuration, the amplifier is simultaneously seeded with a broadband (Deltalambda˜ 0.1nm) and single-frequency Delta v ˜100kHz seed. In this case, several experiments are performed to validate the theoretical predictions with experiments leading to a 203 W polarization maintaining (PM), co-pumped monolithic fiber amplifier demonstration. To the best of our knowledge, this output power is the highest reported in the literature to date for such an amplifier. A time-dependent model of the SBS process initiated from random

  14. Pre-dispersal predation effect on seed packaging strategies and seed viability.

    PubMed

    DeSoto, Lucía; Tutor, David; Torices, Rubén; Rodríguez-Echeverría, Susana; Nabais, Cristina

    2016-01-01

    An increased understanding of intraspecific seed packaging (i.e. seed size/number strategy) variation across different environments may improve current knowledge of the ecological forces that drive seed evolution in plants. In particular, pre-dispersal seed predation may influence seed packaging strategies, triggering a reduction of the resources allocated to undamaged seeds within the preyed fruits. Assessing plant reactions to pre-dispersal seed predation is crucial to a better understanding of predation effects, but the response of plants to arthropod attacks remains unexplored. We have assessed the effect of cone predation on the size and viability of undamaged seeds in populations of Juniperus thurifera with contrasting seed packaging strategies, namely, North African populations with single-large-seeded cones and South European populations with multi-small-seeded cones. Our results show that the incidence of predation was lower on the single-large-seeded African cones than on the multi-small-seeded European ones. Seeds from non-preyed cones were also larger and had a higher germination success than uneaten seeds from preyed cones, but only in populations with multi-seeded cones and in cones attacked by Trisetacus sp., suggesting a differential plastic response to predation. It is possible that pre-dispersal seed predation has been a strong selective pressure in European populations with high cone predation rates, being a process which maintains multi-small-seeded cones and empty seeds as a strategy to save some seeds from predation. Conversely, pre-dispersal predation might not have a strong effect in the African populations with single-large-seeded cones characterized by seed germination and filling rates higher than those in the European populations. Our results indicate that differences in pre-dispersal seed predators and predation levels may affect both selection on and intraspecific variation in seed packaging. PMID:26400794

  15. Catalyst-free growth of ZnO nanowires on ITO seed/glass by thermal evaporation method: Effects of ITO seed layer thickness

    NASA Astrophysics Data System (ADS)

    Alsultany, Forat H.; Hassan, Z.; Ahmed, Naser M.

    2016-07-01

    A seed/catalyst-free growth of ZnO nanowires (ZnO-NWs) on a glass substrate were successfully fabricated using thermal evaporation technique. These nanowires were grown on ITO seed layers of different thicknesses of 25 and 75 nm, which were deposited on glass substrates by radio frequency (RF) magnetron sputtering. Prior to synthesized ITO nanowires, the sputtered ITO seeds were annealed using the continuous wave (CW) CO2 laser at 450 °C in air for 15 min. The effect of seed layer thickness on the morphological, structural, and optical properties of ZnO-NWs were systematically investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-Vis spectrophotometer.

  16. Q-switched fiber laser based on an acousto-optic modulator with injection seeding technique.

    PubMed

    Li, Wencai; Liu, Haowei; Zhang, Ji; Long, Hu; Feng, Sujuan; Mao, Qinghe

    2016-06-10

    The operation mechanism and the pulse property of an actively Q-switched erbium-doped fiber laser based on an acousto-optic modulator (AOM) switch with the injection seeding technique are investigated. Our results show that the Q-switched pulses can be locked to oscillate near a fixed frequency higher than that of the seed laser, though the frequency-shift effect of the AOM impedes stable cavity mode oscillations. The operation mechanism of such Q-switch fiber lasers can be explained by the mutual locking-in among the shifted frequency components originated from the injected coherence seed with the help of the gain dynamics of the Q-switch cavity. Moreover, narrow-linewidth Q-switched pulses with different repetition rates can be obtained with different cavity lengths for incredibly stable output pulses without any use of cavity-stabilized techniques. PMID:27409015

  17. Laser Phase Errors in Seeded FELs

    SciTech Connect

    Ratner, D.; Fry, A.; Stupakov, G.; White, W.; /SLAC

    2012-03-28

    Harmonic seeding of free electron lasers has attracted significant attention from the promise of transform-limited pulses in the soft X-ray region. Harmonic multiplication schemes extend seeding to shorter wavelengths, but also amplify the spectral phase errors of the initial seed laser, and may degrade the pulse quality. In this paper we consider the effect of seed laser phase errors in high gain harmonic generation and echo-enabled harmonic generation. We use simulations to confirm analytical results for the case of linearly chirped seed lasers, and extend the results for arbitrary seed laser envelope and phase.

  18. Detection algorithm for multiple rice seeds images

    NASA Astrophysics Data System (ADS)

    Cheng, F.; Ying, Y. B.

    2006-10-01

    The objective of this research is to develop a digital image analysis algorithm for detection of multiple rice seeds images. The rice seeds used for this study involved a hybrid rice seed variety. Images of multiple rice seeds were acquired with a machine vision system for quality inspection of bulk rice seeds, which is designed to inspect rice seeds on a rotating disk with a CCD camera. Combining morphological operations and parallel processing gave improvements in accuracy, and a reduction in computation time. Using image features selected based on classification ability; a highly acceptable defects classification was achieved when the algorithm was implemented for all the samples to test the adaptability.

  19. Multiple frequency optical mixer and demultiplexer and apparatus for remote sensing

    NASA Technical Reports Server (NTRS)

    Chen, Jeffrey R. (Inventor)

    2010-01-01

    A pulsed laser system includes a modulator module configured to provide pulsed electrical signals and a plurality of solid-state seed sources coupled to the modulator module and configured to operate, responsive to the pulsed electrical signals, in a pulse mode. Each of the plurality of solid-state seed sources is tuned to a different frequency channel separated from any adjacent frequency channel by a frequency offset. The pulsed laser system also includes a combiner that combines outputs from each of the solid state seed sources into a single optical path and an optical doubler and demultiplexer coupled to the single optical path and providing each doubled seed frequency on a separate output path.

  20. Smoke signals and seed dormancy

    PubMed Central

    Waters, Mark T; Nelson, David C

    2011-01-01

    The Arabidopsis thaliana F-box protein MAX2 has been discovered in four separate genetic screens, indicating that it has roles in leaf senescence, seedling photosensitivity, shoot outgrowth and seed germination. Both strigolactones and karrikins can regulate A. thaliana seed germination and seedling photomorphogenesis in a MAX2-dependent manner, but only strigolactones inhibit shoot branching. How MAX2 mediates specific responses to both classes of structurally-related signals, and the origin of its dual role remains unknown. The moss Physcomitrella patens utilizes strigolactones and MAX2 orthologs are present across the land plants, suggesting that this signaling system could have an ancient origin. The seed of parasitic Orobanchaceae species germinate preferentially in response to strigolactones over karrikins, and putative Orobanchaceae MAX2 orthologs form a sub-clade distinct from those of other dicots. These observations suggest that lineage-specific evolution of MAX2 may have given rise to specialized responses to these signaling molecules. PMID:22019642

  1. Functional importance of avian seed dispersers changes in response to human-induced forest edges in tropical seed-dispersal networks.

    PubMed

    Saavedra, Francisco; Hensen, Isabell; Beck, Stephan G; Böhning-Gaese, Katrin; Lippok, Denis; Töpfer, Till; Schleuning, Matthias

    2014-11-01

    Although seed-dispersal networks are increasingly used to infer the functioning of ecosystems, few studies have investigated the link between the properties of these networks and the ecosystem function of seed dispersal by animals. We investigate how frugivore communities and seed dispersal change with habitat disturbance and test whether relationships between morphological traits and functional roles of seed dispersers change in response to human-induced forest edges. We recorded interaction frequencies between fleshy fruited plants and frugivorous bird species in tropical montane forests in the Bolivian Andes and recorded functional bird traits (body mass, gape width and wing tip length) associated with quantitative (seed-removal rate) and qualitative (seed-deposition pattern) components of seed-dispersal effectiveness. We found that the abundance and richness of frugivorous birds were higher at forest edges. More fruits were removed and dispersed seeds were less clustered at edges than in the interior. Additionally, functional and interaction diversity were higher at edges than in the interior, but functional and interaction evenness did not differ. Interaction strength of bird species increased with body mass, gape width and wing tip length in the forest interior, but was not related to bird morphologies at forest edges. Our study suggests that increases in functional and interaction diversity and an even distribution of interaction strength across bird morphologies lead to enhanced quantity and tentatively enhanced quality of seed dispersal. It also suggests that the effects of species traits on ecosystem functions can vary along small-scale gradients of human disturbance. PMID:25182931

  2. Spaced Seed Data Structures for De Novo Assembly.

    PubMed

    Birol, Inanç; Chu, Justin; Mohamadi, Hamid; Jackman, Shaun D; Raghavan, Karthika; Vandervalk, Benjamin P; Raymond, Anthony; Warren, René L

    2015-01-01

    De novo assembly of the genome of a species is essential in the absence of a reference genome sequence. Many scalable assembly algorithms use the de Bruijn graph (DBG) paradigm to reconstruct genomes, where a table of subsequences of a certain length is derived from the reads, and their overlaps are analyzed to assemble sequences. Despite longer subsequences unlocking longer genomic features for assembly, associated increase in compute resources limits the practicability of DBG over other assembly archetypes already designed for longer reads. Here, we revisit the DBG paradigm to adapt it to the changing sequencing technology landscape and introduce three data structure designs for spaced seeds in the form of paired subsequences. These data structures address memory and run time constraints imposed by longer reads. We observe that when a fixed distance separates seed pairs, it provides increased sequence specificity with increased gap length. Further, we note that Bloom filters would be suitable to implicitly store spaced seeds and be tolerant to sequencing errors. Building on this concept, we describe a data structure for tracking the frequencies of observed spaced seeds. These data structure designs will have applications in genome, transcriptome and metagenome assemblies, and read error correction. PMID:26539459

  3. Spaced Seed Data Structures for De Novo Assembly

    PubMed Central

    Birol, Inanç; Chu, Justin; Mohamadi, Hamid; Jackman, Shaun D.; Raghavan, Karthika; Vandervalk, Benjamin P.; Raymond, Anthony; Warren, René L.

    2015-01-01

    De novo assembly of the genome of a species is essential in the absence of a reference genome sequence. Many scalable assembly algorithms use the de Bruijn graph (DBG) paradigm to reconstruct genomes, where a table of subsequences of a certain length is derived from the reads, and their overlaps are analyzed to assemble sequences. Despite longer subsequences unlocking longer genomic features for assembly, associated increase in compute resources limits the practicability of DBG over other assembly archetypes already designed for longer reads. Here, we revisit the DBG paradigm to adapt it to the changing sequencing technology landscape and introduce three data structure designs for spaced seeds in the form of paired subsequences. These data structures address memory and run time constraints imposed by longer reads. We observe that when a fixed distance separates seed pairs, it provides increased sequence specificity with increased gap length. Further, we note that Bloom filters would be suitable to implicitly store spaced seeds and be tolerant to sequencing errors. Building on this concept, we describe a data structure for tracking the frequencies of observed spaced seeds. These data structure designs will have applications in genome, transcriptome and metagenome assemblies, and read error correction. PMID:26539459

  4. Fluorescent Screening of Transgenic Arabidopsis Seeds without Germination1

    PubMed Central

    Wei, Shu; Bravdo, Ben-Ami; Shoseyov, Oded

    2004-01-01

    In this paper, we describe a reliable method for the screening and selection of Arabidopsis transgenic seeds within minutes without germination. Expression of the Aspergillus niger β-glucosidase gene BGL1 in the plant's endoplasmic reticulum was used as a visual marker, together with 4-methylumbelliferyl-β-d-glucopyranoside (MUGluc) as a substrate. Subsequent to incubation in a solution of MUGluc at room temperature for 2 to 15 min, transgenic seeds expressing BGL1 demonstrated a distinct fluorescent signal under UV light. Optimal screening conditions at room temperature were achieved between 75 and 450 μm MUGluc, at a pH of 2.5 to 5.0 and 2 to 5 min of incubation. No significant loss of viability was detected in transgenic seeds that were redried and stored for 45 d after incubation in MUGluc solution for 2 to 150 min. Transgenic plants expressing BGL1 displayed normal phenotypes relative to the wild type. Selection frequency was 3.1% ± 0.34% for the fluorescence selection method, while kanamycin resistant selection resulted in only 0.56% ± 0.13% using the same seed batch. This novel selection method is nondestructive, practical, and efficient, and eliminates the use of antibiotic genes. In addition, the procedure shortens the selection time from weeks to minutes. PMID:15208418

  5. Unique Method for Generating Design Earthquake Time History Seeds

    SciTech Connect

    R. E. Spears

    2008-07-01

    A method has been developed which takes a single seed earthquake time history and produces multiple similar seed earthquake time histories. These new time histories possess important frequency and cumulative energy attributes of the original while having a correlation less than 30% (per the ASCE/SEI 43-05 Section 2.4 [1]). They are produced by taking the fast Fourier transform of the original seed. The averaged amplitudes are then pared with random phase angles and the inverse fast Fourier transform is taken to produce a new time history. The average amplitude through time is then adjusted to encourage a similar cumulative energy curve. Next, the displacement is modified to approximate the original curve using Fourier techniques. Finally, the correlation is checked to ensure it is less than 30%. This process does not guarantee that the correlation will be less than 30% for all of a given set of new curves. It does provide a simple tool where a few additional iterations of the process should produce a set of seed earthquake time histories meeting the correlation criteria.

  6. Seed Mucilage Improves Seedling Emergence of a Sand Desert Shrub

    PubMed Central

    Yang, Xuejun; Baskin, Carol C.; Baskin, Jerry M.; Liu, Guangzheng; Huang, Zhenying

    2012-01-01

    The success of seedling establishment of desert plants is determined by seedling emergence response to an unpredictable precipitation regime. Sand burial is a crucial and frequent environmental stress that impacts seedling establishment on sand dunes. However, little is known about the ecological role of seed mucilage in seedling emergence in arid sandy environments. We hypothesized that seed mucilage enhances seedling emergence in a low precipitation regime and under conditions of sand burial. In a greenhouse experiment, two types of Artemisia sphaerocephala achenes (intact and demucilaged) were exposed to different combinations of burial depth (0, 5, 10, 20, 40 and 60 mm) and irrigation regimes (low, medium and high, which simulated the precipitation amount and frequency in May, June and July in the natural habitat, respectively). Seedling emergence increased with increasing irrigation. It was highest at 5 mm sand burial depth and ceased at burial depths greater than 20 mm in all irrigation regimes. Mucilage significantly enhanced seedling emergence at 0, 5 and 10 mm burial depths in low irrigation, at 0 and 5 mm burial depths in medium irrigation and at 0 and 10 mm burial depths in high irrigation. Seed mucilage also reduced seedling mortality at the shallow sand burial depths. Moreover, mucilage significantly affected seedling emergence time and quiescence and dormancy percentages. Our findings suggest that seed mucilage plays an ecologically important role in successful seedling establishment of A. sphaerocephala by improving seedling emergence and reducing seedling mortality in stressful habitats of the sandy desert environment. PMID:22511952

  7. CT, MR, and ultrasound image artifacts from prostate brachytherapy seed implants: The impact of seed size

    SciTech Connect

    Robertson, Andrew K. H.; Basran, Parminder S.; Thomas, Steven D.; Wells, Derek

    2012-04-15

    Purpose: To investigate the effects of brachytherapy seed size on the quality of x-ray computed tomography (CT), ultrasound (US), and magnetic resonance (MR) images and seed localization through comparison of the 6711 and 9011 {sup 125}I sources. Methods: For CT images, an acrylic phantom mimicking a clinical implantation plan and embedded with low contrast regions of interest (ROIs) was designed for both the 0.774 mm diameter 6711 (standard) and the 0.508 mm diameter 9011 (thin) seed models (Oncura, Inc., and GE Healthcare, Arlington Heights, IL). Image quality metrics were assessed using the standard deviation of ROIs between the seeds and the contrast to noise ratio (CNR) within the low contrast ROIs. For US images, water phantoms with both single and multiseed arrangements were constructed for both seed sizes. For MR images, both seeds were implanted into a porcine gel and imaged with pelvic imaging protocols. The standard deviation of ROIs and CNR values were used as metrics of artifact quantification. Seed localization within the CT images was assessed using the automated seed finder in a commercial brachytherapy treatment planning system. The number of erroneous seed placements and the average and maximum error in seed placements were recorded as metrics of the localization accuracy. Results: With the thin seeds, CT image noise was reduced from 48.5 {+-} 0.2 to 32.0 {+-} 0.2 HU and CNR improved by a median value of 74% when compared with the standard seeds. Ultrasound image noise was measured at 50.3 {+-} 17.1 dB for the thin seed images and 50.0 {+-} 19.8 dB for the standard seed images, and artifacts directly behind the seeds were smaller and less prominent with the thin seed model. For MR images, CNR of the standard seeds reduced on average 17% when using the thin seeds for all different imaging sequences and seed orientations, but these differences are not appreciable. Automated seed localization required an average ({+-}SD) of 7.0 {+-} 3.5 manual

  8. SEEDS: A Celebration of Science

    NASA Technical Reports Server (NTRS)

    Melton, Bob

    1991-01-01

    The major goal of the project of Space Exposed Experiment Developed for Students (SEEDS) was to stimulate interest in science through the active involvement of all participants. Youthful investigators utilized the basic and integrated science process skills as they conducted the research necessary to complete the data reports used in the compilation of this document. Participants described many unique activities designed to promote critical thinking and problem solving. Seeds made a significant impact toward enhancing the teaching, learning, and enjoyment of science for students worldwide.

  9. SEEDS Moving Group Status Update

    NASA Technical Reports Server (NTRS)

    McElwain, Michael

    2011-01-01

    I will summarize the current status of the SEEDS Moving Group category and describe the importance of this sub-sample for the entire SEEDS survey. This presentation will include analysis of the sensitivity for the Moving Groups with general a comparison to other the other sub-categories. I will discuss the future impact of the Subaru SCExAO system for these targets and the advantage of using a specialized integral field spectrograph. Finally, I will present the impact of a pupil grid mask in order to produce fiducial spots in the focal plane that can be used for both photometry and astrometry.

  10. Past agricultural land use and present-day fire regimes can interact to determine the nature of seed predation.

    PubMed

    Stuhler, John D; Orrock, John L

    2016-06-01

    Historical agriculture and present-day fire regimes can have significant effects on contemporary ecosystems. Although past agricultural land use can lead to long-term changes in plant communities, it remains unclear whether these persistent land-use legacies alter plant-consumer interactions, such as seed predation, and whether contemporary disturbance (e.g., fire) alters the effects of historical agriculture on these interactions. We conducted a study at 27 sites distributed across 80,300 ha in post-agricultural and non-agricultural longleaf pine woodlands with different degrees of fire frequency to test the hypothesis that past and present-day disturbances that alter plant communities can subsequently alter seed predation. We quantified seed removal by arthropods and rodents for Tephrosia virginiana and Vernonia angustifolia, species of conservation interest. We found that the effects of land-use history and fire frequency on seed removal were contingent on granivore guild and microhabitat characteristics. Tephrosia virginiana removal was greater in low fire frequency sites, due to greater seed removal by rodents. Although overall removal of V. angustifolia did not differ among habitats, rodents removed more seeds than arthropods at post-agricultural sites and non-agricultural sites with low fire frequencies, but not at non-agricultural sites with high fire frequencies. Land-use history and fire frequency also affected the relationship between microhabitat characteristics and removal of V. angustifolia. Our results suggest that historical agriculture and present-day fire regimes may alter seed predation by shifting the impact of rodent and arthropod seed predators among habitats, with potential consequences for the establishment of rare plant species consumed by one or both predators. PMID:26905418