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1

Adhesive Contact Sweeper  

NASA Technical Reports Server (NTRS)

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.

Patterson, Jonathan D.

1993-01-01

2

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

SciTech Connect

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.

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. [Inter University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067 (India)

2006-07-15

3

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...

4

Plasma sweeper. [Patents  

DOEpatents

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.

Motley, R.W.; Glanz, J.

1982-10-25

5

Oil sweeper method and apparatus  

SciTech Connect

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.

De V. A.; Van W. P.

1982-04-20

6

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...

7

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

PubMed Central

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.

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

2013-01-01

8

Acute Lung Function Response to Dust in Street Sweepers  

PubMed Central

Background: Sweepers are chronically exposed to dust raised during sweeping. Dust is regarded as the most influential agent and it is perceived as a frequent cause of respiratory system illness and may cause acute and chronic lung function impairment. Aims: The aim of this study was to determine the acute lung function changes in sweepers exposed to dust generated from street sweeping. Material and Methods: This study was conducted in central Karnataka, India, on 25 female sweepers and 25 healthy female control subjects who were comparable in age, height and weight. The pulmonary function test was performed in controls, sweepers before and after sweeping, by using RMS medspiror and results were compared by Student’s unpaired ‘t’ test. Results: The results showed a significant reduction in percent predicted values and mean values of FVC, FEV1, PEFR, FEF25-75% and FEF 200-1200 between sweepers and their matched controls. Pulmonary function after sweeping also showed a significant decrease. Conclusions: On comparing the pulmonary functions of sweepers before and after sweeping, it was concluded that inhalation of dust acutely affected the lung function of sweepers in India and that sweepers were at a risk of developing occupation related lung function impairment. We recommend that the workers should use protective face masks and do wet sweeping instead of dry sweeping during sweeping activity.

Johncy S., Smilee; G., Dhanyakumar; Samuel T., Vivian; K.T., Ajay; Bondade, Suresh Y.

2013-01-01

9

Nuclear-powered space debris sweeper  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

10

Two-frequency injection-seeded Nd:YAG laser  

Microsoft Academic Search

Dual longitudinal mode (DLM) operation of a Nd:YAG laser is achieved by simultaneously injection seeding with two seed frequencies. We show that the relative energy in the two frequency components can be adjusted by varying the relative seed power, and that they have excellent spatial, angular, and temporal overlap. The result is a deeply modulated 1.06-?m pulse with a modulation

T. D. Raymond; A. V. Smith

1995-01-01

11

Narrowband alexandrite laser injection seeded with frequency dithered diode laser  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

12

Slippage effect on energy modulation in seeded free-electron lasers with frequency chirped seed laser pulses  

NASA Astrophysics Data System (ADS)

Free-electron lasers (FELs) seeded with external lasers hold great promise for generating high power radiation with nearly transform-limited bandwidth in the soft x-ray region. However, it has been pointed out that the initial seed laser phase error will be amplified by the frequency up-conversion process, which may degrade the quality of the output radiation produced by a harmonic generation scheme. In this paper, theoretical and simulation studies on frequency chirp amplification in seeded FEL schemes with slippage effect taken into account are presented. It is found that the seed laser imperfection experienced by the electron beam can be significantly smoothed by the slippage effect in the modulator when the slippage length is comparable to the seed laser pulse length. This smoothing effect allows one to preserve the excellent temporal coherence of seeded FELs in the presence of large frequency chirp in the seed laser. Our studies show that the tolerance on frequency chirp in the seed laser for generating nearly transform-limited soft x-ray pulses in seeded FELs is much looser than previously thought and fully coherent radiation at nanometer wavelength may be reached with current technologies.

Feng, Chao; Deng, Haixiao; Wang, Guanglei; Wang, Dong; Zhao, Zhentang; Xiang, Dao

2013-06-01

13

Frequency shifts in injection-seeded optical parametric oscillators with phase mismatch  

Microsoft Academic Search

We have observed a frequency shift in the output signal pulses relative to the seed frequency in an injection-seeded, singly resonant, critically phase-matched, pulsed optical parametric oscillator in which phase mismatch was intentionally introduced. The observed shifts can be large compared with the linewidth of the signal pulse, are approximately linear in phase mismatch, and increase with increasing pump fluence.

T. D. Raymond; W. J. Alford; A. V. Smith; Mark S. Bowers

1994-01-01

14

Absolute frequency stabilization of an injection-seeded optical parametric oscillator  

Microsoft Academic Search

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 HeâNe 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

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

1996-01-01

15

Single-frequency, injection-seeded Ti:sapphire ring laser with high temporal precision  

Microsoft Academic Search

A three-mirror Ti:sapphire ring laser with a cavity length of 11 cm is injection seeded with a single-mode laser diode operating at 784 nm. The seed beam is injected into the ring cavity through the output coupler. The incident seed power is 11 mW. The ring laser is pumped with a frequency-doubled Nd:YAG laser. An efficiency of 40% is demonstrated.

Charles E. Hamilton

1992-01-01

16

A Q-switched alexandrite laser injection seeded by a rubidium absorption frequency matched diode laser  

Microsoft Academic Search

We developed a narrowband Q-switched alexandrite laser injection seeded by a diode laser which was frequency stabilized to the 780 nm rubidium atomic absorption line. We were able to get injection seeded single-mode output pulses of ~ 10 mJ per pulse energy at 780 nm with ~ 200 ns fwhm pulse duration. By using a side injection scheme and an

K. Choi; S. H. Lin; Eric Korevaar; C. S. Liu

1992-01-01

17

Tunable CW Single-Frequency Source for Injection Seeding 2-micrometer Lasers.  

National Technical Information Service (NTIS)

This program developed a stable, single-frequency, continuous-wave (CW) optical parametric oscillators (OPOs) for the application of injection seeding pulsed lasers. Progress has been made in the demonstration and performance characterization of doubly re...

R. L. Byer

1990-01-01

18

Absolute frequency stabilization of an injection-seeded optical parametric oscillator  

NASA Astrophysics Data System (ADS)

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-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'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 25-MHz residual error in the absolute frequency stabilities of the pump, signal, and idler waves is experimentally demonstrated, which is roughly 30% of the 160-MHz near-transform-limited linewidths of the signal and idler pulses.

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

1996-03-01

19

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

SciTech Connect

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.

Stupakov, G.; /SLAC

2011-11-18

20

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

NASA Technical Reports Server (NTRS)

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.

Brown, Lamarr A.

1992-01-01

21

Effect of low frequency ultrasonic assisted extraction on the quality of seed oils of Indian origin  

Microsoft Academic Search

The study gives an insight into the effect of low frequency ultrasonic enhancement of solvent extraction on the quality of non-edible oils (Jatropha and Pongamia as model seed varieties) in comparison to conventional methods of extraction i.e. direct reflux or soxhlet extraction using hexane. A series of experiments have been carried out to study the effect of variables; solute to

Savita Kaul; Garima Sharma; Jyoti Porwal; Neha Bisht

2011-01-01

22

Injection-Seeded, Single-Frequency, Q Switched Erbium:Glass Laser for Remote Sensing  

Microsoft Academic Search

We have built and characterized an injection-seeded, Q -switched, flash-lamp-pumped, eye-safe Er:glass laser that is suitable for coherent remote sensing. The output of the device is a 400-ns, single-frequency, transform-limited pulse of 1 mJ at 1.552 m.

Andrew J. McGrath; Jesper Munch; Gerald Smith; Peter Veitch

1998-01-01

23

Injection seeded frequency stabilized Nd:YAG ring oscillator following a Pound-Drever-Hall scheme  

Microsoft Academic Search

An injection seeded Nd:YAG laser oscillator has been set up and frequency stabilized following an rf-sideband scheme. This dual rod oscillator emits pulses with 23 ns duration and 20 mJ energy. The beam quality is almost diffraction limited (M2=1.2). The frequency stability was characterized with a heterodyne method to 1.0 MHz root mean square (rms). This oscillator will serve as

Alexander Sträßer; Thomas Waltinger; Martin Ostermeyer

2007-01-01

24

Self-seeded single-frequency laser peening method  

DOEpatents

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.

Dane, C. Brent (Livermore, CA); Hackel, Lloyd (Livermore, CA); Harris, Fritz B. (Rocklin, CA)

2009-08-11

25

Self-seeded single-frequency laser peening method  

DOEpatents

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.

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

2012-06-26

26

A Q-switched alexandrite laser injection seeded by a rubidium absorption frequency matched diode laser  

NASA Astrophysics Data System (ADS)

We developed a narrowband Q-switched alexandrite laser injection seeded by a diode laser which was frequency stabilized to the 780 nm rubidium atomic absorption line. We were able to get injection seeded single-mode output pulses of ˜ 10 mJ per pulse energy at 780 nm with ˜ 200 ns fwhm pulse duration. By using a side injection scheme and an active cavity length control technique high efficiency injection locking was obtained with small injection power. This system was used as an illumination source for atomic line filters with excellent long term stability and day-to-day reliability.

Choi, K.; Lin, S. H.; Korevaar, Eric; Liu, C. S.

1992-04-01

27

Injection-seeded optical parametric oscillator for efficient difference frequency generation in mid-IR  

Microsoft Academic Search

The design and performance of an injection-seeded pulsed parametric oscillator (OPO) is described for efficient difference frequency generation (DFG) in AgGaSe2 and AgGaS2 crystals. A LiNbO3 OPO with unstable-resonator is injection-seeded by another LiNbO3 OPO of narrow linewidth having a grating in cavity. The resulting narrow bandwidth, low divergent signal and idler waves are mixed in AgGaSe2 and AgGaS2 crystals

S. Haidar; H. Ito

1999-01-01

28

Simultaneous Amplification of Terahertz Difference Frequencies by an Injection-Seeded Semiconductor Laser Amplifier at 850 nm  

Microsoft Academic Search

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,

Shuji Matsuura; Pin Chen; Geoffrey A. Blake; J. C. Pearson; Herbert M. Pickett

1998-01-01

29

3D imaging of tomato seeds using frequency domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

A fast imaging system that can reveal internal sample structures is important for research and quality controls of seeds. Optical coherence tomography (OCT) is a non-invasive optical imaging technique that can acquire high speed, high resolution depth-resolved images in scattering samples. It has found numerous applications in studying various biological tissues and other materials in vivo. A few studies have reported the use of OCT in studying seed morphology. However, 3D imaging of internal seed structure has not been reported before. In this study, we used a frequency domain OCT system to image tomato seeds. The system has a central wavelength of 844nm with a 46.8 nm FWHM bandwidth. The requirement for depth scan was eliminated by using a Fourier domain implementation. The B-scan imaging speed was limited by the spectroscopic imaging CCD at 52 kHz. The calibrated system has a 6.7?m depth resolution and a 15.4?m lateral resolution. Our results show that major seed structures can be clearly visualized in OCT images.

Fan, Chuanmao; Yao, Gang

2012-05-01

30

Frequency response of a cold-wire in a flow seeded with oil particles  

Microsoft Academic Search

Experiments have been carried out to investigate the effects of aging on the frequency response of a fine cold-wire located\\u000a in a flow seeded with oil particles used for laser Doppler anemometry. Transfer functions are shown to depend strongly on\\u000a the running time. Photo-micrographs show that the contamination effect is due to discrete droplets, the diameter of which\\u000a increases with

F. Weiss; P. Paranthoën; J. C. Lecordier

2005-01-01

31

Focal Plane Detector System for the MSU/FSU Sweeper Magnet  

NASA Astrophysics Data System (ADS)

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.

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

2002-10-01

32

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

33

Tunable CW single-frequency source for injection seeding 2-micrometer lasers  

NASA Astrophysics Data System (ADS)

This program developed stable, single-frequency, continuous-wave (CW) optical parametric oscillators (OPOs) for the application of injection seeding pulsed lasers. Progress has been made in the demonstration and performance characterization of a doubly resonant optical parametric oscillator (DROs) operating near degeneracy pumped by 532-nm CW radiation obtained from second harmonic generation of diode-array-pumped Nd:YAG lasers. It was observed that the OPO reproduced the coherence of the pump radiation with little additional noise. A detailed analysis of the tuning and control properties of the DRO helpful for development of active stabilization techniques has been completed. Design considerations for a 2-micron DRO based on this analysis are presented. Stabilization of the DRO requires synchronized control of at least three parameters; temperature, pump frequency, and applied potential for electro-optic tuning are considered. Research on this topic is continuingly motivated by the exceptional coherence and tuning properties of the OPO and applications involving optical frequency synthesis that will extend far beyond injection seeding.

Byer, Robert L.

1990-06-01

34

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

PubMed

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

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

2012-07-30

35

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

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

36

Path optimization for Space Sweeper with Sling-Sat: A method of active space debris removal  

NASA Astrophysics Data System (ADS)

This paper provides a path optimization strategy for space debris removal, focusing on the proposed Space Sweeper with Sling-Sat (4S) mission. 4S captures and ejects debris plastically, exploiting the impulsive momentum exchanges in place of fuel. Ejected debris are sent to lower perigee orbits, or to re-enter the atmosphere. The optimization method searches for the most efficient sequence of events to remove debris of unknown masses. For a fixed time interval and number of debris interactions n, the optimized solution predicts a set of n thrust impulses, n debris captures, and n debris ejections. Optimization is performed using an evolutionary algorithm that solves the combinatory problem of selecting the debris interaction order, ejection velocities, and sequence timing, while optimizing fuel cost and effectiveness towards debris mitigation. The first debris interaction is then applied to the system, and the process is repeated after interacting with each object. In this way, an in-orbit mission is simulated, and the results support the feasibility of 4S mission.

Missel, Jonathan; Mortari, Daniele

2013-10-01

37

Moisture content and bulk density dependence of dielectric properties of safflower seed in the radio frequency range  

Microsoft Academic Search

The dielectric properties of safflower seeds were measured over a frequency range of 50kHz to 10MHz at moisture content in a range of 5.33–16.48% dry basis (d.b.) with bulk density which changed between 553.6 and 638.8kg\\/m3 using parallel-plate capacitor sample holder. Effects of the parameters such as moisture content, bulk density and frequency on the dielectric properties were studied. The

Kamil Sacilik; Celik Tarimci; Ahmet Colak

2007-01-01

38

A shrunken-2 transgene increases maize yield by acting in maternal tissues to increase the frequency of seed development.  

PubMed

The maize (Zea mays) shrunken-2 (Sh2) gene encodes the large subunit of the rate-limiting starch biosynthetic enzyme, ADP-glucose pyrophosphorylase. Expression of a transgenic form of the enzyme with enhanced heat stability and reduced phosphate inhibition increased maize yield up to 64%. The extent of the yield increase is dependent on temperatures during the first 4 d post pollination, and yield is increased if average daily high temperatures exceed 33 °C. As found in wheat (Triticum aestivum) and rice (Oryza sativa), this transgene increases maize yield by increasing seed number. This result was surprising, since an entire series of historic observations at the whole-plant, enzyme, gene, and physiological levels pointed to Sh2 playing an important role only in the endosperm. Here, we present several lines of evidence that lead to the conclusion that the Sh2 transgene functions in maternal tissue to increase seed number and, in turn, yield. Furthermore, the transgene does not increase ovary number; rather, it increases the probability that a seed will develop. Surprisingly, the number of fully developed seeds is only ?50% of the number of ovaries in wild-type maize. This suggests that increasing the frequency of seed development is a feasible agricultural target, especially under conditions of elevated temperatures. PMID:22751213

Hannah, L Curtis; Futch, Brandon; Bing, James; Shaw, Janine R; Boehlein, Susan; Stewart, Jon D; Beiriger, Robert; Georgelis, Nikolaos; Greene, Thomas

2012-06-01

39

Online/offline injection seeding system with high frequency-stability and low crosstalk for water vapor DIAL  

NASA Astrophysics Data System (ADS)

A compact and rugged distributed feedback (DFB) laser system has been developed as online–offline injection seeder for the laser transmitter of a ground-based water vapor differential absorption lidar (WV DIAL) near 820 nm. The frequency stability of this injection seeder system shows a standard deviation of only 6.3 MHz and a linewidth of less than 4.6 MHz during continuous operation of more than 14 h. These values by far exceed the requirements for WV DIAL. By use of a novel technique based on an electro-optic deflector (EOD), alternating online–offline wavelength switching is achieved for each shot of the seeded laser with 250 Hz with a response time of less than 10 µs and very low crosstalk between the channels of only 33 dB. As a result, a spectral purity of 99.95% is reached by the WV DIAL transmitter which again fulfills the requirements for WV DIAL measurements with high accuracy. Because moveable parts are not present in the seeding system, this setup is significantly less sensitive to acoustic vibrations and ambient temperature drifts during field experiments than other seeding systems which use external cavity diode lasers (ECDL) and mechanical switches. By our new seeding system not only the requirements for ground-based water-vapor DIAL are met but also for space-borne WV DIAL applications that pose even higher demands to the frequency stability and spectral purity of the laser transmitters.

Späth, Florian; Metzendorf, Simon; Behrendt, Andreas; Wizemann, Hans-Dieter; Wagner, Gerd; Wulfmeyer, Volker

2013-11-01

40

Injection Seeding of a Q-Switched Alexandrite Laser: Study of Frequency Stabilization.  

National Technical Information Service (NTIS)

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 s...

L. A. Brown

1992-01-01

41

Fast resonance-detection technique for single-frequency operation of injection-seeded Nd:YAG lasers  

Microsoft Academic Search

A new technique for maintaining single-frequency output from injection-seeded Nd:YAG lasers is described. It involves quickly sweeping the slave-cavity longitudinal-mode spectrum when the flash lamps have created a maximum population inversion. An interference signal is detected by fast electronics, and the Q switch is opened when the slave cavity is resonant with the injected field.

S. W. Henderson; E. H. Yuen; E. S. Fry

1986-01-01

42

Development of High Power Infrared Optical Parametric Amplification Laser System Seeded by Self-difference Frequency Generation Pulses  

NASA Astrophysics Data System (ADS)

We report on our recent development of a femtosecond infrared laser system based on self-phase-stabilized seed by difference-frequency generation of supercontinuum obtained with so-called hollow fiber compression technique and two-stage optical parametric amplification. After the final amplifier, we obtained pulses with duration of < 40 fs, tunable center wavelength from 1.2 to 1.8 ?m, maximum pulse energy of > 500 ?J and as a first demonstration of this new laser system, we generated high-harmonics up to 47th order in a tube target filled with Xe gas.

Kanai, Tsuneto; Weber, Sébastien; Zaïr, Amelle; Hutchison, Christopher; Siegel, Thomas; Oppermann, Malte; Hutchinson, Simon; Witting, Tobias; Brugnera, Leonardo; Ganeev, Rashid A.; Azuma, Toshiyuki; Midorikawa, Katsumi; Marangos, Jonathan P.

43

Development of narrow-linewidth Yb- and Er- fiber lasers and frequency mixing for ArF excimer laser seeding  

NASA Astrophysics Data System (ADS)

We propose and report a 193 nm narrow-linewidth light generation by a frequency mixing of Yb and Er-fiber lasers as the seed for an ArF excimer laser. The Yb-fiber laser includes a pulsed distributed feedback (DFB) or external cavity diode laser (ECDL), acousto-optic modulator(AOM), fiber amplifiers and an Yb:YAG single crystal fiber (SCF) power amplifier with more than 7 W output. The Er-fiber laser consists of a continuous-wave (CW) DFB laser, a semiconductor optical amplifier (SOA), and fiber amplifiers. The second harmonic generation (SHG) and the fourth harmonic generation (FHG) of Yb laser at 515 nm and 258 nm reach 5 W and 1.5 W, respectively. Two stages of sum-frequency generation (SFG) produce the power of 100 mW for 193 nm laser by use of CLBO crystals.

Xuan, Hongwen; Zhao, Zhigang; Igarashi, Hironori; Ito, Shinji; Kakizaki, Kouji; Kobayashi, Yohei

2014-03-01

44

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

PubMed

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

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

2012-01-30

45

Injection seeding; I: Theory  

SciTech Connect

Injection seeding has proven to be a practical method of controlling the spectral output of a laser in an efficient and reliable manner. To achieve satisfactory injection seeding performance, a sufficiently large seed must be employed. To characterize the required seed, an injection seeding theory is developed here which establishes two interrelated concepts, threshold for injection seeding and spectral purity of the laser output. Rather than utilizing numerical techniques to solve the differential equations, closed-form expressions for the threshold are developed for not only common continuous wave injection seeding but pulsed injection seeding as well. In addition, effects of alignment of the seed to the resonator, both in position and angle, and effects of frequency mismatch, or difference between the seed and the resonant frequencies of the resonator, are taken into account. Expressions for the threshold utilize readily measurable experimental parameters. Spectral purity of the laser output and its consequences on the required seed power or energy are also explored.

Barnes, N.P.; Barnes, J.C. (NASA Langley Research Center, Hampton, VA (United States))

1993-10-01

46

A 275-W Multitone Driven All-Fiber Amplifier Seeded by a Phase-Modulated Single-Frequency Laser for Coherent Beam Combining  

Microsoft Academic Search

We present what we believe to be a new approach of multitone driven amplifier for power scaling and coherent beam combining. A novel multitone seed is generated by a sine wave phase-modulated single-frequency laser and used for stimulated Brillouin scattering suppression of the amplifier. The theory for coherent beam combining of multitone lasers is presented for the first time. Weoptimize

Xiaolin Wang; Pu Zhou; Jingyong Leng; Wenbo Du; Yanxing Ma; Hu Xiao; Jiajian Zhu; Xiaolin Dong; Xiaojun Xu; Zejin Liu; Yijun Zhao

2011-01-01

47

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

48

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

Microsoft Academic Search

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, one can study the characteristics and the causes of intrapulse frequency variation. These include the effect of the decaying plasma, the thermal gradient due to the energy dissipation

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

1987-01-01

49

Motor disturbances and thalamic electrical power of frequency bands' improve by grape seed extract in animal model of Parkinson's disease  

PubMed Central

Objective: Previous studies showed that grape seed extract (GSE) is an excellent natural substance with potent antioxidant effect and free radical scavenger. This study aimed to evaluate the effect of GSE on motor dysfunctions and thalamic local Electroencephalography (EEG) frequency bands' powers in rats with Parkinson's disease (PD). Materials and Methods: In this study 8 µg 6-hydroxydopamine (6-OHDA) dissolved in 2 µl normal saline containing 0.01% ascorbic acid was infused into right medial forebrain bundle (MFB) to make an animal model of PD. Rats with PD received four weeks GSE (100 mg/kg, p.o.) after apomorphine-induced rotation test. Spontaneous motor tests and also thalamic ventroanterior nucleus (AV) local EEG recording were done in freely moving rats in all groups. Results: Chronic treatment of PD rats with GSE could influence potentially frequency bands' powers of thalamic VA and improve post-lesion motor dysfunctions significantly (p<0.05 and p<0.01, respectively). Conclusion: Our findings suggest that GSE modulates the CNS function and has beneficial effects on the direct and indirect striato-thalamo-cortical pathways in PD. GSE acts as a new and potent natural free radical scavenger which removes oxidants produced by neurotoxin 6-OHDA in brain. Therefore, it reinforces electrical power of remained thalamic VA neurons and thereby improves post-lesion motor disorders.

Sarkaki, Alireza; Eidypour, Zainab; Motamedi, Freshteh; keramati, keivan; Farbood, Yaghoub

2012-01-01

50

Characterization of frequency-tripled nanosecond pulsed Ti:sapphire laser injection seeded by a frequency-scanning cw Ti:sapphire laser by use of optogalvanic spectroscopy of silicon atoms  

Microsoft Academic Search

The performance of a narrow-linewidth nanosecond pulsed deep-UV coherent light source consisting of a frequency-tripled nanosecond pulsed Ti:sapphire laser injection seeded by a frequency-scanning cw Ti:sapphire laser has been characterized by using optogalvanic spectroscopy of silicon atoms as a diagnostic. The envelope of the optogalvanic spectrum indicates the pure Doppler broadening of silicon atoms, which was estimated to be as

Yasutomo Shiomi; Kuniaki Kyutoku; Hiroshi Kumagai; Ataru Kobayashi

2006-01-01

51

The effects of Fusilade (Fluazifop- p -butyl) on germination, mitotic frequency and ?-amylase activity of lentil ( Lens culinaris Medik.) seeds  

Microsoft Academic Search

In this study, seed germination percentages, effects on phases of mitosis and ?-amylase enzyme activity of lentil seeds treated\\u000a with four different concentrations (0.25, 0.5, 1 and 1.5%) of Fusilade (Fluazifop-p-butyl) were determined. Median EC (effective concentration) values were calculated according to seed germination percentages\\u000a after treatment for 72 h. Germination percentages of primary lentil roots decreased with increasing Fusilade concentrations.

Feruzan Dane; Filiz Ekinci Sanal; Tulin Aktac

2007-01-01

52

A shrunken-2 Transgene Increases Maize Yield by Acting in Maternal Tissues to Increase the Frequency of Seed Development[W  

PubMed Central

The maize (Zea mays) shrunken-2 (Sh2) gene encodes the large subunit of the rate-limiting starch biosynthetic enzyme, ADP-glucose pyrophosphorylase. Expression of a transgenic form of the enzyme with enhanced heat stability and reduced phosphate inhibition increased maize yield up to 64%. The extent of the yield increase is dependent on temperatures during the first 4 d post pollination, and yield is increased if average daily high temperatures exceed 33°C. As found in wheat (Triticum aestivum) and rice (Oryza sativa), this transgene increases maize yield by increasing seed number. This result was surprising, since an entire series of historic observations at the whole-plant, enzyme, gene, and physiological levels pointed to Sh2 playing an important role only in the endosperm. Here, we present several lines of evidence that lead to the conclusion that the Sh2 transgene functions in maternal tissue to increase seed number and, in turn, yield. Furthermore, the transgene does not increase ovary number; rather, it increases the probability that a seed will develop. Surprisingly, the number of fully developed seeds is only ?50% of the number of ovaries in wild-type maize. This suggests that increasing the frequency of seed development is a feasible agricultural target, especially under conditions of elevated temperatures.

Hannah, L. Curtis; Futch, Brandon; Bing, James; Shaw, Janine R.; Boehlein, Susan; Stewart, Jon D.; Beiriger, Robert; Georgelis, Nikolaos; Greene, Thomas

2012-01-01

53

Optical pulse generation at frequencies up to 20 GHz using external-injection seeding of a gain-switched commercial Fabry-Perot laser  

Microsoft Academic Search

We demonstrate that by using strong external-injection seeding of gain-switched Fabry-Perot (FP) lasers, it is possible to generate optical pulses at repetition rates far in excess of the laser bandwidth. Experimental results illustrate the generation of optical pulses at frequencies up to 20 GHz from a FP laser with a 3-dB bandwidth of only 8 GHz. The optical pulses generated

L. P. Barry; P. Anandarajah; A. Kaszubowska

2001-01-01

54

Frequency jitter and spectral width of an injection-seeded Q-switched Nd:YAG laser for a Doppler wind lidar  

Microsoft Academic Search

The design of a 50 Hz single longitudinal mode, diode-pumped and frequency-tripled Nd:YAG master oscillator power amplifier\\u000a is described, and the first measurements of output parameters are presented. The laser oscillator is injection-seeded by a\\u000a tuneable monolithic Nd:YAG ring laser and frequency stabilized by minimising the Q-switch build-up time. The laser system\\u000a will be an integral part of an airborne instrument

T. Schröder; C. Lemmerz; O. Reitebuch; M. Wirth; C. Wührer; R. Treichel

2007-01-01

55

Experimental investigation on amplification and coherence properties of a single-frequency and dual-single-frequency narrow-linewidth fiber Raman amplifier employing a switchable narrow-linewidth seed laser  

NASA Astrophysics Data System (ADS)

We demonstrate a narrow-linewidth fiber Raman amplifier (NL-FRA) operating at single-frequency (SF) and dual-single-frequency (DSF) to study the amplification and coherence properties. A switchable NL seed laser at a central wavelength of 1079.7 nm is utilized to provide SF and DSF signal light for FRA. The signal light is Raman amplified to 791 mW and 1.07 W, respectively. Measurements of spectrum and frequency spectrum indicate that there is no significant indication of stimulated Brillouin scattering (SBS) and four-wave mixing (FWM). The experimental investigation on coherence properties of SF and DSF NL-FRA indicates that the optical-path-difference-control and control-servomechanism-system for coherent beam combination (CBC) of DSF NL-FRAs are more strictly required, but still feasible.

Xu, Jiangming; Wu, Wuming; Xiao, Hu; Leng, Jinyong; Hou, Jing

2011-11-01

56

Single-frequency, Q-switched Ho:YAG laser at room temperature injection-seeded by two F-P etalons-restricted Tm, Ho:YAG laser.  

PubMed

We demonstrated a 1.91 ?m pumped, injection-seeded Q-switched Ho:YAG laser operating at room temperature. By inserting two Fabry-Perot etalons into the laser cavity, single-frequency Tm, Ho:YAG seed lasing was achieved at a wavelength of 2090.9 nm, with a typical output power of 60 mW. Single-frequency, nearly transform-limited Q-switched operation of the Ho:YAG laser was achieved by injection seeding. The output energy of the single-frequency Q-switched pulse is 7.6 mJ, with a pulse width of 132 ns and a repetition rate of 100 Hz. We measured the pulse spectrum, half-width of which was 3.5 MHz, by a heterodyne technique. PMID:22660050

Dai, T Y; Ju, Y L; Yao, B Q; Shen, Y J; Wang, W; Wang, Y Z

2012-06-01

57

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)

This thesis explores the design, construction, and applications of the optoelectronic swept-frequency laser (SFL). The optoelectronic SFL is a feedback loop designed around a swept-frequency (chirped) semiconductor laser (SCL) to control its instantaneous optical frequency, such that the chirp characteristics are determined solely by a reference electronic oscillator. The resultant system generates precisely controlled optical frequency sweeps. In particular, we focus on linear chirps because of their numerous applications. We demonstrate optoelectronic SFLs based on vertical-cavity surface-emitting lasers (VCSELs) and distributed-feedback lasers (DFBs) at wavelengths of 1550 nm and 1060 nm. We develop an iterative bias current predistortion procedure that enables SFL operation at very high chirp rates, up to 1016 Hz/sec. We describe commercialization efforts and implementation of the predistortion algorithm in a stand-alone embedded environment, undertaken as part of our collaboration with Telaris, Inc. We demonstrate frequency-modulated continuous-wave (FMCW) ranging and three-dimensional (3-D) imaging using a 1550 nm optoelectronic SFL. We develop the technique of multiple source FMCW (MS-FMCW) reflectometry, in which the frequency sweeps of multiple SFLs are "stitched" together in order to increase the optical bandwidth, and hence improve the axial resolution, of an FMCW ranging measurement. We demonstrate computer-aided stitching of DFB and VCSEL sweeps at 1550 nm. We also develop and demonstrate hardware stitching, which enables MS-FMCW ranging without additional signal processing. The culmination of this work is the hardware stitching of four VCSELs at 1550 nm for a total optical bandwidth of 2 THz, and a free-space axial resolution of 75 microns. We describe our work on the tomographic imaging camera (TomICam), a 3-D imaging system based on FMCW ranging that features non-mechanical acquisition of transverse pixels. Our approach uses a combination of 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%.

Vasilyev, Arseny

58

Seed Dispersal  

NSDL National Science Digital Library

In this outdoor activity and bingo-like game, learners explore why and how seeds spread far from the plants that produce them. To understand natural adaptions that let seeds and fruit be dispersed, learners make modifications to dried beans and peas so they could be dispersed by natural forces like water, air, or an animal moving from one place to another. In the "Seed-Go" Game, learners match ways that seeds are dispersed, to fill rows on the game board.

Science, Lawrence H.

1979-01-01

59

Seed Size  

NSDL National Science Digital Library

In this activity, learners collect, arrange, and draw various seeds from smallest to biggest. They also estimate how many of the smallest would fit into the biggest. In addition, learners predict how many seeds they would find inside an apple or lemon, and cut open these fruits to check their prediction against the real seed count. The Did You Know section describes the biggest and smallest seeds on Earth.

Science, Lawrence H.

2007-01-01

60

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)

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).

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

1999-01-01

61

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

PubMed

We demonstrate a room-temperature high-power frequency comb source covering the spectral region from 2 to 2.15 ?m. The source is based on a femtosecond erbium-fiber laser operating at 1.55 ?m with a repetition rate of 250 MHz, wavelength-shifted up to 2.06 ?m 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 ?m. 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

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

2014-03-15

62

Traveling Seeds  

NSDL National Science Digital Library

In this activity, learners make three different "seed" types and determine which design flies the farthest. Learners wad a piece of paper, wad a piece of tape, and make a paper helicopter to represent plant seeds. Learners measure and record the distance each seed travels. Use this activity to help learners practice measuring and recording data. This activity guide contains sample questions to ask, literary connections, extensions, and alignment to local and national standards.

Houston, Children'S M.

2014-03-10

63

Many Seeds: Estimating Hidden Seeds  

NSDL National Science Digital Library

In this activity, learners will estimate how many seeds are in a fruit or vegetable, then count to find out. The result: mix estimation with healthy eating. Vary the level of difficulty by using different foods: for younger learners, choose something with up to about 15 seeds inside (e.g. apples, snow peas); for a medium level of difficulty, try melon slices or cucumbers; for more challenge, use pomegranates or mini-pumpkins. Available as a web page or downloadable pdf.

Terc

2010-01-01

64

Verticillium dahliae Race 2-Specific PCR Reveals a High Frequency of Race 2 Strains in Commercial Spinach Seed Lots and Delineates Race Structure.  

PubMed

ABSTRACT 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 studies in ecology, population biology, disease surveillance, and epidemiology at local and global scales, and resistance breeding against race 2 in lettuce and other crops. PMID:24502204

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

2014-07-01

65

Seed Catalogues  

NSDL National Science Digital Library

The Smithsonian Institutions Libraries Web site currently features a unique collection of seed and nursery catalogs dating from 1830 to the present. Online visitors may view a portion of the exhibit, which offers a look at "the history of the seed and agricultural implement business in the United States, as well as provides a history of botany and plant research such as the introduction of plant varieties into the US." Although this site does include much material, gardeners and anyone else with a horticultural bent should enjoy a casual browse through the online exhibit.

66

International Seed Saving Institute: Basic Seed Saving  

NSDL National Science Digital Library

This straightforward site from the International Seed Saving Institute on Basic Seed Saving will be of use to any growers interested in learning how to save seeds from season to season. The site provides links "to specific seed saving instructions for 27 common vegetables" including many favorites like corn, carrots, broccoli, and lettuce. The site also links to a glossary of seed saving terms and a six-step Seed Saving Tutorial.

67

Injection seeding. I. Theory  

Microsoft Academic Search

Injection seeding has proven to be a practical method of controlling the spectral output of a laser in an efficient and reliable manner. To achieve satisfactory injection seeding performance, a sufficiently large seed must be employed. To characterize the required seed, an injection seeding theory is developed here which establishes two interrelated concepts, threshold for injection seeding and spectral purity

Norman P. Barnes; James C. Barnes

1993-01-01

68

Big Seed  

NSDL National Science Digital Library

This iOS app helps develop spatial reasoning and strategic thinking. Users reflect seed squares (horizontally, vertically and diagonally) to grow larger pieces that eventually cover the given design space without spilling over. A graduated set of difficulty levels makes the game accessible to a wide range of ages.

2012-12-06

69

Seed Bargains  

NSDL National Science Digital Library

Children as well as adults are usually intrigued by the ideas of bargains. More seeds for less money is often enough to convince them to buy a larger, cheaper package. In this case, the children are savvy enough to question the value of either package. On

Konicek-Moran, Richard

2008-04-01

70

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

USGS Publications Warehouse

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.

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

2007-01-01

71

Seed Treatment. Bulletin 760.  

ERIC Educational Resources Information Center

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)

Lowery, Harvey C.

72

Seed Magazine  

NSDL National Science Digital Library

Seed is an online (and print) magazine dedicated to increasing the scientific awareness and knowledge of the general public. The site is updated six days a week and features news articles, original-content articles on a variety of science topics, columns, and reviews. "Cribsheets," a downloadable feature, provide brief tutorials on scientific issues and innovations that may occur in everyday conversation. The magazine also features a collection of multimedia materials, such as podcasts, slide shows, and video content. The web site's main page features articles from the latest issue; back issues may be browsed by category, author, or date. Information about subscribing to the print version is also provided.

73

Red peach and seed  

NSDL National Science Digital Library

This peach has only one large seed, as compared to the pomegranate that has many seeds. The peach is like an apple in the way that its seed is surrounded by the entire fruit. The fruit can be eaten by humans, but it is actually there as nourishment and food for the peach seed to grow.

Jack Dykinga (USDA;ARS)

1997-08-01

74

How Seeds Travel  

NSDL National Science Digital Library

Students will rotate around to 7 different stations to identify how the 7 presented seeds travel, whether it be by wind, water, or animal. They will then record it in their plant journals by illustrating the seed, listing its characteristics, and identifying the way in which it travels. Designer Seeds 7 Stations Coconut-Water Maple Seed- Wind Burdock (burrs) - Animals ...

Liston, Mrs

2009-11-09

75

Vegetable Seed Saving Handbook  

NSDL National Science Digital Library

This Vegetable Seed Saving Handbook online is a great resource for anyone wanting to harvest viable Fast Plants seeds to plant right away (as in selection experiments) or save for future use. Follow the instructions for cabbage family seeds (Brassica raps, in particular). If you're planning on saving your seeds, treat Fast Plants seeds as "desiccation-tolerant" as described here: http://howtosaveseeds.com/store.php

76

The Seed Biology Place  

NSDL National Science Digital Library

This remarkable site was created by Professor Gerhard Leubner and his colleagues at the University of Freiburg in Germany. Here, visitors can take advantage of a veritable cornucopia of reference materials related to seed biology, such as diagrams and illustrations of seed germination, plant hormones, endosperm weakening, and seed dormancy. Neophytes may wish to start by looking at the Seed Structure and Anatomy area, which features a concise and well-written overview of the structure, anatomy, and morphology of mature seeds. The same section contains information on the seed structure of the castor bean and other legumes. Another fascinating section on the site is dedicated to Seed Evolution. Visitors can discover a wealth of information here, including such topics as the evolutionary trends of angiosperm seeds and the seed ferns of the Late Permian period. All told, the site is a wonderful resource, and visitors will want to share it with friends.

Leubner, Gerhard

2012-02-10

77

Seed Treatment. Sale Publication 4076.  

ERIC Educational Resources Information Center

This guide gives information about types of seeds that may require chemical protection against pests, seed treatment pesticide formulations, seed treatment methods, labeling treated seed, and safety and environmental precautions. (Author/BB)

Wamsley, Mary Ann, Ed.; Vermeire, Donna M., Ed.

78

Inside a Seed  

NSDL National Science Digital Library

This image from Biology by Kenneth R. Miller and Joseph Levine illustrates the five most important parts of a seed: the seed coat, the endosperm, and the embryo's primary root, cotyledon, and embryonic leaves.

Foundation, Wgbh E.

2003-09-26

79

Inside a Seed  

NSDL National Science Digital Library

This image from Biology by Kenneth R. Miller and Joseph Levine illustrates the five most important parts of a seed: the seed coat, the endosperm, and the embryos primary root, cotyledon, and embryonic leaves.

2007-12-12

80

Kenaf seed oil  

Microsoft Academic Search

Summary  Kenaf oil is obtained from the seeds ofHibiscus cannabinus L. The procedure for extracting the oil is practically the same as is used in extracting cotton seed oil. The seed is ground\\u000a and pressed without decortication because the episperm is strongly adherent to the kernel and also because of the peculiar\\u000a shape of the seed. Up to 20% oil of

Mario Lewy

1947-01-01

81

Needs of Seeds  

ERIC Educational Resources Information Center

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…

Keeley, Page

2011-01-01

82

Injection Seeding Of A Q-Switched Alexandrite Laser  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

83

Use of grain and seed dielectric properties for moisture measurement  

Microsoft Academic Search

The importance of moisture measurement in grain and seed is discussed, and a brief history of the development of moisture sensing instruments, based on sensing electrical properties of these materials, is presented. Data are presented graphically on the permittivities or dielectric properties of grain and seed showing their variation with frequency, moisture content, temperature, and bulk density, and references are

Stuart O. Nelson; Samir Trabelsi

2011-01-01

84

The seed nuclear proteome.  

PubMed

Understanding the regulatory networks coordinating seed development will help to manipulate seed traits, such as protein content and seed weight, in order to increase yield and seed nutritional value of important food crops, such as legumes. Because of the cardinal role of the nucleus in gene expression, sub-proteome analyses of nuclei from developing seeds were conducted, taking advantage of the sequences available for model species. In this review, we discuss the strategies used to separate and identify the nuclear proteins at a stage when the seed is preparing for reserve accumulation. We present how these data provide an insight into the complexity and distinctive features of the seed nuclear proteome. We discuss the presence of chromatin-modifying enzymes and proteins that have roles in RNA-directed DNA methylation and which may be involved in modifying genome architecture in preparation for seed filling. Specific features of the seed nuclei at the transition between the stage of cell divisions and that of cell expansion and reserve deposition are described here which may help to manipulate seed quality traits, such as seed weight. PMID:23267364

Repetto, Ombretta; Rogniaux, Hélène; Larré, Colette; Thompson, Richard; Gallardo, Karine

2012-01-01

85

Polyamines and related enzymes in rice seeds differing in germination potential  

Microsoft Academic Search

In ungerminated rice seeds, (Japonica rice variety, CV Tapei 309), the content of free amines (putrescine, spermidine, spermine, tyramine) was higher in seed lots having a low germination frequency compared to those with high germination potential. Conversely, amine conjugates (di-feruloylputrescine, di-feruloylspermidine, diferuloyldiaminopropane and feruloyltyramine) decreased with loss of viability. Thus, these compounds appeared to constitute biochemical markers of seed viability.

L. Bonneau; M. Carré; J. Martin-Tanguy

1994-01-01

86

Microwave resonator technique for moisture content and mass determination in single soybean seeds  

Microsoft Academic Search

Principles are presented relating to the use of a microwave resonant cavity for determining simultaneously the mass and moisture content of individual soybean seeds. Measurement of the resonant frequency shift and change in the transmission characteristics of the cavity when the soybean seed is inserted provides the necessary information for calculating the mass of water in the seed and the

A. W. Kraszewski; S. O. Nelson

1994-01-01

87

Water impermeable seed dormancy  

Microsoft Academic Search

Viable seeds that do not imbibe water and thus fail to germinate in an apparently favorable environment are commonly termed\\u000a impermeable or hard seed. This physical, exogenous dormancy is especially common in species of the Fabaceae. The ecological\\u000a significance of hard seed includes the ability to rapidly recolonize burnt areas after fire and to withstand ingestion by\\u000a animals and birds.

M. Philip Rolston

1978-01-01

88

Frequency Analysis of the Laser Biospeckle  

NASA Astrophysics Data System (ADS)

This research work presents a study of beans seed tissue (Phaseolous vulgaris, L.) optical interactions with laser aiming to contribute to the development of biospeckle techniques applied to the recognition of bean seed tissue vitality when contaminated with fungi, by differentiating the generated frequency spectra. Biospeckle is an interference optic phenomenon occurring when a laser beam reaches a surface exhibiting some dynamic process, due to biological activities or purely physical changes. The technique involves image processing to distinguish each different active material contribution present in the seed, by means of the procedure known as ``Moment of Inertia'' and frequency analysis. Frequency analysis was carried by Fourier Transform preceded by module of convolution. A great challenge in this area is to identify the elements contribution to increase biospeckle activity, such as water, microorganisms, among others. This research work is recognized to provide an important step aiming to characterize the interaction of laser with biological material. Three groups of bean seeds were employed, one represented by healthy seeds and two groups composed of seeds contaminated with Aspergillus spp as well as with Fusarium spp fungi. The biospeckle analysis considered the activity and its frequency spectra. The seeds were each one exposed to laser in a random order. The results reveled differences in the average values of MI of the three seed groups. Also, some different harmonics in the biospeckle pattern in a same group as well as among seed groups had been noticed. These results allow confirming that it is possible to differentiate contaminated seeds from non-contaminated ones by means of biospeckle frequency analysis.

Enes, Adilson M.; Rabelo, Giovanni F.; Júnior, Roberto A. Braga; Dal Fabbro, Inácio M.; Vilela, Michelle

2008-04-01

89

Imprinting and Seed Development  

Microsoft Academic Search

Fertilization Seeds consist of three genetically distinct components: embryo, endosperm, and seed coat. In plants, mitosis follows meiosis to produce the haploid phase of the plant life cycle, the male and female gametophytes. The angiosperm female gametophyte, the site of fertilization, is completely embedded within the maternal sporophytic tissues of the ovule. The most prevalent type of mature female gametophyte

Mary Gehring; Yeonhee Choi; Robert L. Fischer

2004-01-01

90

Seeds of Success.  

ERIC Educational Resources Information Center

Project SEED, begun in 1963, is an integral part of mathematics instruction in several urban districts. To provide at-risk students with tough academic challenges, Project SEED recruits mathematicians and scientists from universities, corporations, and the community to work in elementary and middle-school classrooms. Program tips are provided.…

Ebrahimi, Hamid

1999-01-01

91

Tanzania Seed Multiplication.  

National Technical Information Service (NTIS)

Tanzania has long suffered from lack of an organized seed production and distribution system. The report presents the results of an impact assessment of a project (1/70-12/82) to increase the quality and quantity of seeds produced in Tanzania.

C. B. Ratchford L. R. Meyers B. J. Ndunguru M. S. Zak

1985-01-01

92

When Seed Dispersal Matters  

NSDL National Science Digital Library

This peer-reviewed resource from Bioscience journal is about the varying importance of seed dispersal within plant communities. A profusion of fruit forms implies that seed dispersal plays a central role in plant ecology, yet the chance that an individual seed will ultimately produce a reproductive adult is low to infinitesimal. Extremely high variance in survival implies that variations in fruit production or transitions from seed to seedling will contribute little to population growth. The key issue is that variance in survival of plant life-history stages, and therefore the importance of dispersal, differs greatly among and within plant communities. In stable communities of a few species of long-lived plants, variances in seed and seedling survival are immense, so seed-to-seedling transitions have little influence on overall population dynamics. However, when seedlings in different circumstances have very different chances of survival--in ecological succession, for example, or when dispersed seeds escape density-dependent mortality near parent trees--the biased survival of dispersed seeds or seedlings in some places rather than others results in pervasive demographic impacts.

HENRY F. HOWE and MARIA N. MIRITI (;)

2004-07-01

93

Needs of Seeds  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about seeds. It specifically probes to find out if students recognize that a seed has needs, similar to other organisms that allow it to develop into the next stage of its life cycle.

Eberle, Francis; Tugel, Joyce; Keeley, Page

2007-01-01

94

Millennium Seed Bank Project  

NSDL National Science Digital Library

A number of organizations have developed a concerted interest in establishing seed banks to protect the wide diversity of existing plant life for future generations. The Royal Botanic Gardens is currently working on their own project, whose ultimate goal is to collect 24,000 plant species. So far, they have successfully secured samples from almost all of the native flowering plants in the United Kingdom, and their work continues on in the present day. Many visitors to the site will want to peruse their homepage and the helpful graphic (a peapod) helps orient first-time visitors to the various sections on the site, such as "Solving Seed Problems" and their publications and data area. The site also includes a field manual for those who would like to collect their own seeds in the field as well as data about the seeds collected thus far in the Seed Information Database.

2005-01-01

95

Telomeres and seed banks.  

PubMed

We have found that a progressive loss of telomeric sequences occurs from high molecular weight DNA with an increasing appearance at low molecular weight as the periods of storage in the dry state were extended in time to provide seed germination loss from 98 to 0%. Telomere distribution would appear to follow the general pattern of DNA random fragmentation that occurs in the embryos of seeds stored in the dry state, but there are also indications of an overall telomere loss from DNA as a consequence of storage. There is a need for a convenient "equality marker" for the seeds that can be monitored over time. Reviewing the implications of our results very carefully we believe that there is considerable potential in the use of telomere sequences to mark embryo ageing of seeds held in Seed Banks. PMID:17427414

Boubriak, I; Pouschuk, V; Grodzinsky, A; Osborne, Daphne J

2007-01-01

96

Injection seeding for single-mode operation  

SciTech Connect

Spectrally narrow, pulsed outputs consisting of almost a single mode have been obtained from an optically-pumped high-power (200kW) D{sub 2}O laser by adopting the injection seeding method, where single-mode radiation (seed pulse) from a low-power, compact D{sub 2}O laser has been injected into the main D{sub 2}O laser. Spectrally narrow outputs with high power having spectral widths as narrow as 5 MHz have been obtained, when the seed pulses with frequency tuned to one longitudinal mode of the main D{sub 2}O laser have been injected at a time sufficiently before the lasing of the main laser took place. The experimental results have been compared with those of numerical simulation modified to include the injection field with varying injection times.

Sasaki, K.; Takahashi, O.; Takada, N. [Nagoya Univ. (Japan)] [and others

1995-12-01

97

Magnetic stimulation of marigold seed  

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

98

Defoliation effects on Bromus tectorum seed production: Implications for grazing  

USGS Publications Warehouse

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.

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

2008-01-01

99

Seed Dispersal: Lemurs  

NSDL National Science Digital Library

Trees in Madagascar's forests have evolved traits that promote the dispersal of their seeds by lemurs. This two-minute radio program focuses on the interaction between forest plants and lemurs--the main seed dispersers in the forests. A guest scientist explains why lemurs ingest seeds that are large relative to their body size. He also notes that the fruits of Madagascar's trees have evolved to be strong smelling but drably colored in accordance with lemurs' keen sense of smell and poor vision. The program is available in text and audio formats. The latter includes audio of ring-tailed lemurs. Copyright 2005 Eisenhower National Clearinghouse

Planet, Pulse O.

2007-09-20

100

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

PubMed Central

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 to be restricted to regions of nutrient-impoverished soil or to fire-prone regions.

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

2007-01-01

101

Seed output and the seed bank in Vallisneria americana (Hydrocharitaceae).  

PubMed

Seed banks and sexual reproduction are known to be significant in colonization and re-establishment of some aquatic macrophyte communities. For highly clonal aquatic macrophytes, however, there is a lack of information on seed production and seed fate as compared with annual sexual species. The seed bank for three populations of Vallisneria americana in the Huron-Erie corridor of the Great Lakes was sampled and quantified in the spring of 1994, and related to seed production in the previous season at these sites. Seed deposition rates during 1994 were also assessed. Sites varied in the proportion of plants flowering and in their tertiary sex ratios, but did not differ in seed numbers produced per unit area. The size of the seed bank was not significantly related to the previous season's seed output, and estimates of seed deposition in the following year tended to be approximately tenfold greater than seed densities found in the seed bank. The stages between seed production and subsequent seed germination are generally very dynamic, with dispersal, mortality, and predation as likely regulating factors. The potential for seedling establishment in V. americana needs to be assessed more fully before the role of seeds in population processes can be determined. PMID:21708549

Lokker, C; Lovett-Doust, L; Lovett-Doust, J

1997-10-01

102

Tomato seeds for LDEF  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

103

Tropical Tree Seed Manual.  

National Technical Information Service (NTIS)

The Tropical Tree Seed Manual is a one-volume reference manual for students, technicians, and scientists that provides comprehensive internationally compiled data about tropical trees. The emphasis is on species of the Americas; however, a number of tropi...

J. A. Vozzo

2002-01-01

104

Fishing for Seeds.  

ERIC Educational Resources Information Center

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)

Science and Children, 2001

2001-01-01

105

Easy PEAsy Seed Germination  

NSDL National Science Digital Library

In this activity, learners determine the necessary conditions for pea seed germination. This activity encourages learners to make predictions and think about how they might investigate the effects of variables like light, temperature, and moisture.

Dyson, Paul

2012-04-09

106

Quality Seed Production,  

National Technical Information Service (NTIS)

In many arid and semiarid regions, seed production has not kept pace with the development of new varieties. To remedy the situation, the International Center for Agricultural Research in the Dry Areas (ICARDA) is working closely with national programs and...

A. J. G. van Gastel J. Kerley

1988-01-01

107

Microencapsulated Cloud Seeding Materials.  

National Technical Information Service (NTIS)

A process was developed for encapsulating hygroscopic, cloud-seeding agents, sodium chloride and urea. The encapsulation process involves depositing the coating polymer, ethylcellulose, onto finely divided powders using a phase separation-coacervation tec...

J. L. Anderson

1971-01-01

108

Seeds in Flight  

ERIC Educational Resources Information Center

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)

Martin, Willard K.

1978-01-01

109

Dormancy in Plant Seeds  

Microsoft Academic Search

\\u000a Seed dormancy has been studied intensely over the past decades and, at present, knowledge of this plant trait is at the forefront\\u000a of plant biology. The main model species is Arabidopsis thaliana, an annual weed, possessing nondeep physiological dormancy. This overview presents the state-of-the-art of seed dormancy\\u000a research, focusing mainly on physiological and molecular-genetic aspects in this species. It has

Henk W. M. Hilhorst; William E. Finch-Savage; Julia Buitink; William Bolingue; Gerhard Leubner-Metzger

110

CloudSeeding  

NSDL National Science Digital Library

This Topic in Depth begins with a Web site from the Oklahoma Weather Modification Program called Cloud Physics - The Basics (1 ). Students are encouraged to initiate a debate on the controversy surrounding the issue of inducing or enhancing precipitation. Next, the Texas Water Resources Institute Web site, Does Weather Modification Really Work? (3 ) provides a more basic description of cloudseeding. The site offers several categories including The Science of Cloud Seeding, A Brief History of Weather Modification in Texas, Legal and Policy Issues, Current and Future Activities, and more. The Western Kansas Weather Modification Program offers the next site, Aircrew Pictures 2001 (4 ). The page contains pictures of the planes and crew involved in the program as well as pictures from the plane during a mission. Other links on the site contain radar, data, and other information. The next site from ABCNEWS.com is an article entitled Weather as a Weapon? (5 ) The piece explorers what might happen "on some battlefield of the future where the US military could gain a tactical advantage by changing the weather." A discussion on the possibilities of changing the weather, an Air Force research paper and several other links are provided to learn more. The 6th site maintained by the North Dakota State Water Commission is entitled Atmospheric Resources-Photos and Videos (6 ). Here, visitors can find more photographs of cloudseeding equipment and most notably three videos of cloudseeding planes in action. Atmospherics Incorporated, an operations and research company in the field of applied meteorology, provides the next site, The Physical Basis for Seeding Clouds (7 ). The page describes techniques for cloud seeding and has a link to photographs of pyrotechnic seeding devices. The last site provided by North American Weather Consultants, Inc. is titled, Cloud Seeding -Frequently Asked Questions (8 ). The site briefly answers questions such as When did application of modern cloud seeding technology begin?, Is cloud seeding effective?, and Do the commonly used seeding materials pose any direct health or environmental risks?

2002-01-01

111

Dropping rates of elaiosome-bearing seeds during transport by ants ( Formica polyctena Foerst.): Implications for distance dispersal  

NASA Astrophysics Data System (ADS)

In a deciduous forest, foraging ants collect elaiosome-bearing seeds and carry them to their nests. Some of the seeds reach the nest and are concentrated there. Others may be dropped by ants during transport. The dropped seeds enter the soil seed pool. However, they might be repeatedly removed by other ant individuals and carried again in the direction of the nest. Rates of seed dropping and repeated removals must be known to evaluate the effect of ant workers on dispersal distance of seeds. The rate of seed dropping is predicted to depend on size of seeds and of elaiosomes, both of which vary among plant species, and on the size of the ant workers. Mark-recapture experiments were used to evaluate dropping rates of seeds of five myrmecochorous and diplochorous plants ( Chelidonium majus L., Asarum europaeum L., Viola matutina Klok., V. mirabilis L., V. hirta L.) during their transport by the ant Formica polyctena Foerst. In the series of species A. europaeum - V. hirta - V. mirabilis - Ch. majus - V. matutina, the dropping rate increased. Small workers dropped seeds of A. europaeum more often than did large ones, while seeds of V. hirta were dropped by ants of different size classes with the same frequency. Across species, dropping rates of seeds were negatively correlated with the rate at which ants removed them from the depot. The number of seeds which reach the nests is the other important parameter of seed dispersal. This parameter depends on dropping rates: seeds with lower dropping rates have higher chances of being deposited in nests. Diplochores usually produce many small seeds, which are characterised by low removal rates and high dropping rates during transport by ants. Obligate myrmecochores produce rather few large seeds, which have high removal rates and low dropping rates. To analyse the significance of seed dropping in the dispersal distance of seeds, a computer simulation based on two factors [(i) seed number produced by a plant; (ii) dropping rate of seeds] is proposed.

Gorb, Stanislav N.; Gorb, Elena V.

1999-09-01

112

Dielectric characteristics of rape-seed oil  

Microsoft Academic Search

This paper deals with the investigation of fundamental dielectric characteristics of rape-seed oil considered to be a substitute of mineral oil in power transformers. The 50 Hz breakdown voltage is comparable to normal mineral oil, e.g. more than 50 kV\\/2.5 mm. Furthermore, the permittivity εR and the dielectric loss factor tan ? for various temperatures and frequencies were measured. Using

R. Badent; K. Kist; B. Ruggemeier; W. Zierhut; A. J. Schwab

1998-01-01

113

Injection seeded terahertz-wave parametric generator  

Microsoft Academic Search

We report on the development of a widely tunable (frequency: 0.6-2.6 THz), injection-seeded THz-wave parametric generator (is-TPG), which operates at room temperature. The spectral resolution (<100 NfHz, 0.0033 cm-1) is the Fourier transform limit of the nanosecond THz-wave pulse. The continuous scanning and narrow spectral bandwidth of the is-TPG were verified in the absorption spectrum of low-pressure water vapor.

K. Kawase; K. Imai; H. Minamide; J. I. Shikata; H. Ito

2002-01-01

114

Optically seeded stimulated Raman scattering of aqueous sulfate microdroplets  

NASA Astrophysics Data System (ADS)

Optically seeded, stimulated Raman scattering is demonstrated for 25- mu m -radius water droplets containing sulfate. Frequency-doubled Nd:YAG laser-excited Stokes radiation from the 3450- cm -1 O-H-stretching vibration of water provides the seed for morphology-dependent stimulated Raman scattering from the nu 1 vibration of sulfate that is excited by a dye laser. Seeding enhances the otherwise weaker signal for low concentrations of the anion, thereby reducing the solute detection limit, by a method that does not require changing of the droplet composition.

Pasternack, Louise; Fleming, James W.; Owrutsky, Jeffrey C.

1996-07-01

115

Precocious Germination during In Vitro Growth of Soybean Seeds 1  

PubMed Central

Immature Glycine max (L.) Merrill seeds were grown and matured in liquid medium at 25°C under fluorescent light. In standard medium containing minerals, 146 millimolar sucrose and 62.5 millimolar glutamine (osmolality 0.24), precocious germination seldom occurred with a starting seed size of less than 300 milligrams fresh weight. Frequency of precocious germination increased with increased starting seed size. Sucrose concentration strongly affected precocious germination while glutamine concentration had no effect. Starting with 300 to 350 milligrams fresh weight seeds, treatments which reduced the sucrose concentration or lowered the osmolality of the culture medium stimulated precocious germination, and increased the fresh weight growth but not the dry weight growth of seeds. Increasing the osmolality to 0.38 with sucrose or mannitol prevented precocious germination without reducing dry weight accumulation in seeds. In medium with initially low osmolality, precocious germination was inhibited by addition of 1 to 100 micromolar abscisic acid to the medium without a reduction in seed growth. During growth and maturation of large soybean seeds in vitro, precocious germination and other abnormal tissue growth can be prevented by high sucrose or mannitol concentrations in the medium or by addition of abscisic acid.

Obendorf, Ralph L.; Wettlaufer, Scott H.

1984-01-01

116

Automated seed manipulation and planting  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

117

Spike-based and seed-based selection for preharvest sprouting resistance in wheat  

Microsoft Academic Search

The utility of spike- and seed-based mass selection techniques for improving preharvest sprouting resistance in heterogeneous wheat (Triticum spp.) populations was evaluated. Sorting seed by size improved selection efficiency in some cases, putatively by physiological synchronization. Progeny testing, as well as changes in frequency of red-kernelled types, indicate effectiveness of both spike- and seed-based mass selection for reduced preharvest sprouting.

A. H. Paterson; M. E. Sorrells

1990-01-01

118

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

SciTech Connect

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.

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

1986-03-01

119

Single axial mode operation of a Q-switched Nd: YAG oscillator by injection seeding  

SciTech Connect

The authors have achieved stable Fourier transform limited single axial mode operation of an unstable resonator Nd:YAG oscillator by injection seeding of an external signal. A detailed theoretical and experimental treatment of axial mode selection via injection seeding is presented. This study shows that the axial mode selection process in Q-switched lasers via injection seeding is quite different from the frequency locking in CW lasers via injection locking.

Park, Y.K.; Byer, R.L.; Giuliani, G.

1984-02-01

120

Single axial mode operation of a Q-switched Nd:YAG oscillator by injection seeding  

Microsoft Academic Search

Stable Fourier transform-limited single axial mode operation of an unstable resonator Nd:YAG oscillator has been achieved by injection-seeding of an external signal. A detailed theoretical and experimental treatment of axial mode selection via injection seeding is presented. This study shows that the axial mode selection process in Q-switched lasers via injection seeding is quite different from the frequency locking in

Y. K. Park; G. Giuliani

1984-01-01

121

Single axial mode operation of a Q-switched Nd:YAG oscillator by injection seeding  

SciTech Connect

Stable Fourier transform-limited single axial mode operation of an unstable resonator Nd:YAG oscillator has been achieved by injection-seeding of an external signal. A detailed theoretical and experimental treatment of axial mode selection via injection seeding is presented. This study shows that the axial mode selection process in Q-switched lasers via injection seeding is quite different from the frequency locking in CW lasers via injection locking. 34 references.

Park, Y.K.; Giuliani, G.; Byer, R.L.

1984-02-01

122

Seed banks and seed population dynamics of halophytes  

Microsoft Academic Search

In this review I will describe the importance of seed banks and thepopulation dynamics of seeds on the distribution of species in salinehabitats. The main questions being examined in this review include: 1.Does the seed bank represent the flora of the entire salinity gradient or isit restricted to the species in each zonal community? 2. Is the size andspecies composition

Irwin A. Ungar

2001-01-01

123

Seed Dormancy and Germination  

PubMed Central

Seed dormancy allows seeds to overcome periods that are unfavourable for seedling established and is therefore important for plant ecology and agriculture. Several processes are known to be involved in the induction of dormancy and in the switch from the dormant to the germinating state. The role of plant hormones, the different tissues and genes involved, including newly identified genes in dormancy and germination are described in this chapter, as well as the use transcriptome, proteome and metabolome analyses to study these mechanistically not well understood processes.

Bentsink, Leonie; Koornneef, Maarten

2008-01-01

124

Light Water Seed Blanket Reactor.  

National Technical Information Service (NTIS)

A seed blanket light water breeder reactor and a light water seed blanket thorium burner reactor have been considered. Both these proposals make use of geometry control in order to regulate reactivity. (Atomindex citation 11:538563)

1979-01-01

125

Physical View of Cloud Seeding  

ERIC Educational Resources Information Center

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)

Tribus, Myron

1970-01-01

126

Dispersal of Transgenes through Maize Seed Systems in Mexico  

PubMed Central

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.

Dyer, George A.; Serratos-Hernandez, J. Antonio; Perales, Hugo R.; Gepts, Paul; Pineyro-Nelson, Alma; Chavez, Angeles; Salinas-Arreortua, Noe; Yunez-Naude, Antonio; Taylor, J. Edward; Alvarez-Buylla, Elena R.

2009-01-01

127

Seeds: A Celebration of Science.  

ERIC Educational Resources Information Center

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…

Melton, Bob

128

Keywords Lithocarpus densiflora . Seed reserves  

Microsoft Academic Search

To investigate how seed reserves affect early seedling performance, we conducted a factorial green- house experiment using Lithocarpus densiflora (Tanoak). Seedlings were grown from large (5.8±0.7 g) and small (3.2±0.4 g) seeds and, following shoot emergence, seeds were either removed or left attached. Seedlings were harvested for quantification of biomass and ? 13 C at seven

P. G. Kennedy; N. J. Hausmann; E. H. Wenk; T. E. Dawson

129

Cloud Seeding Frequently Asked Questions  

NSDL National Science Digital Library

This site is provided by North American Weather Consultants, Inc. The site briefly answers questions such as "when did application of modern cloud seeding technology begin?," "Is cloud seeding effective?," and "Do the commonly used seeding materials pose any direct health or environmental risks?"

Griffith, Don; Solak, Mark

2008-01-07

130

Corridors cause differential seed predation.  

SciTech Connect

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.

JOHN L. ORROCk; ELLEN I. DAMSCHEN

2005-06-01

131

Seeds of the world : Journey to Forever  

NSDL National Science Digital Library

Seeds of the world: Journey to Forever - No seeds, no food, vanishing seeds, most crop varieties already lost, rendezvous with extinction, seed saving, biodiversity, world hunger This site discusses the importance of seeds to humans and the global economy. It provides extension information about genetically modified seeds and the Green Revolution.

Addison, Keith

2001-01-01

132

Measurement of grain and seed moisture and density through permittivity relationships  

Microsoft Academic Search

The importance of moisture measurement in grain and seed is discussed, and a brief history of the development of moisture sensing instruments, based on sensing of dielectric properties of these materials, is presented. Data are presented graphically on the permittivities or dielectric properties of grain and seed showing their variation with frequency, moisture content, temperature, and bulk density, and references

Stuart O. Nelson; Samir Trabelsi

2010-01-01

133

Studies in seed dormancy  

Microsoft Academic Search

When dormant hazel seeds were subjected to six weeks chilling at 5° C their subsequent transfer to 20° C resulted in the accumulation of gibberellin (GA) followed by germination. In the presence of either phosphon D or ß-chlorethyltrimethylammonium chloride (CCC) at 20° C there was inhibition of both GA accumulation and germination, a finding consistent with the hypothesis that GA

I. Arias; P. M. Williams; J. W. Bradbeer

1976-01-01

134

Apparatus for Planting Seeds.  

National Technical Information Service (NTIS)

The patent application relates to a process whereby seeds are punch planted by an apparatus comprising a disk equipped with a plurality of punches rotatably mounted on a frame. The punch disk is eccentrically driven to insure that the punches are perpendi...

D. E. Wilkins W. J. Conley

1979-01-01

135

The SEED Initiative  

ERIC Educational Resources Information Center

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…

Teich, Carolyn R.

2011-01-01

136

The Seeds of Change.  

ERIC Educational Resources Information Center

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…

Viola, Herman J.

1991-01-01

137

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

PubMed Central

• 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 during seed maturation plays an important role in induction of dormancy.

YAMAZAKI, JUN; MIYOSHI, KAZUMITSU

2006-01-01

138

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

PubMed

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

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

2013-01-01

139

[Seed dispersal efficiency of forest herbaceous plant species by the ant Myrmica ruginodis].  

PubMed

We compared the ability of 33 plant species collected in forest to have their seeds dispersed by the wood red ant Myrmica ruginodis. The elaiosome-bearing seeds (species Chelidonium majus, Colchicum autumnale, Luzula forsteri, Viola reichenbachiana, Luzula multiflora, Melica uniflora) and the small and light caryopses of the grasses (Holcus mollis, Agrostis capillaris, Deschampsia flexuosa, Poa trivialis, Holcus lanatus) are the most efficiently collected by ants. The seed quantity removed by ants is correlated negatively with their length. No significant correlation is found between the rate of seed removal and the frequency of the plants in the field at the scale of the study. PMID:18355754

Delatte, Emilie; Chabrerie, Olivier

2008-04-01

140

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

PubMed Central

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.

Padilla-Camberos, Eduardo; Martinez-Velazquez, Moises; Flores-Fernandez, Jose Miguel; Villanueva-Rodriguez, Socorro

2013-01-01

141

Construct Arguments: Pumpkin Seeds  

NSDL National Science Digital Library

This professional development video clip shows students engaged in the Common Core Practice Standard #3âConstruct viable arguments for conclusions reached and critique the reasoning of others. In this lesson, learners work in groups to discuss and revise their estimates of how many seeds are in a small pumpkin. Additional resources include a video transcript, teaching tips, and a link to a professional development reflection activity based upon the video.

Boston, Wghb

2013-01-01

142

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

NASA Astrophysics Data System (ADS)

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 fate, and may be helpful in developing models to predict seed shadows and recruitment patterns of large-seeded trees.

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

2011-11-01

143

Frequency Generating Source: Frequency Synthesizers.  

National Technical Information Service (NTIS)

A mode of fractional frequency harmonic generation obtained by the modulation of a square wave reference signal is considered. The produced spectrum exhibits a particular structure. The longer the fractional part of the frequency of the modulating wave is...

N. Yahyabey S. Hassani

1992-01-01

144

Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887.  

PubMed

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

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

145

Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887  

NASA Technical Reports Server (NTRS)

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.

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

146

New genes in traditional seed systems: diffusion, detectability and persistence of transgenes in a maize metapopulation.  

PubMed

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

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

2012-01-01

147

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

USGS Publications Warehouse

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.

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

2013-01-01

148

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

PubMed Central

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.

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

2012-01-01

149

Metal deposition using seed layers  

DOEpatents

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.

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

2013-11-12

150

Wheat Seed System in Ethiopia: Farmers' Varietal Perception, Seed Sources, and Seed Management  

Microsoft Academic Search

Knowledge and information on farmers' perception and its influence on adoption of modern wheat varieties, awareness and source of new wheat production technology, wheat seed sources, and on-farm seed-management practices remain sporadic in Ethiopia. This study was conducted to understand the functioning of the wheat seed system in four major wheat-growing areas of Ethiopia. A total of 304 wheat growers

Zewdie Bishaw; P. C. Struik; A. J. G Van Gastel

2010-01-01

151

Teaching Through Trade Books: Secrets of Seeds  

NSDL National Science Digital Library

From a tiny radish seed to a giant coconut, seeds come in a multitude of shapes and sizes. They all share one amazing secret: the potential to grow into a new plant when conditions are right. In this month's column, students observe a variety of seeds, match seeds to the plants they grow into, explore what seeds need to germinate and grow, and design investigations with seeds.

Morgan, Emily; Ansberry, Karen

2009-02-01

152

Automated seed manipulation and planting  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

153

Physical properties of psyllium seed  

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

154

Physical properties of psyllium seed  

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

155

Two light yellow seed embryos  

NSDL National Science Digital Library

The style of the carpel of a flower (female reproductive structure) leads to the ovary. The ovary holds eggs, which become seeds once fertilized. Seeds hold embryos. The embryo becomes a new plant. In animals, the embryo becomes a new animal.

Katie Hale (CSUF;Biological Sciences)

2007-06-19

156

A preliminary investigation of pre-dispersal seed predation by Acanthoscelides schrankiae Horn (Coleoptera: Bruchidae) in Mimosa bimucronata (DC.) Kuntze trees.  

PubMed

This is the first record of Acanthoscelides schrankiae Horn. feeding in seeds of Mimosa bimucronata (DC.) Kuntze. We investigated the pattern of oviposition and seed exploitation by A. schrankiae, and the distribution of mature fruits and seed predation in the inflorescences. We also compared the percentage of predated seeds, the total dry weight of fruits and non-predated seeds, the percentage of aborted seeds, and the percentage of non-emergent insects, among different quadrants of the M. bimucronata canopy. To determine the occurring species, the emergence of bruchids and parasitoids was observed in the laboratory, resulting altogether, only in individuals of A. schrankiae and Horismenus sp. (Hymenoptera: Eulophidae) species, respectively. Mean number of fruits produced in the median region of inflorescence was significantly higher than in the inferior and superior regions, and the frequencies (observed and expected) of predated and non-predated seeds differed among the different regions of inflorescence. Females of A. schrankiae laid their eggs on fruits, and larvae, after emergence, perforated the exocarp to reach the seeds. Most fruits presented one to three eggs and only one bruchid larva was observed in each seed. The highest value of the rate "number of eggs/fruit" and the highest percentage of predated seeds were recorded in April. Dry weight of fruits (total) and seeds (non-predated), proportions of predated seeds, seed abortions, and non-emergent seed predators, were evenly distributed in the canopy. PMID:17607452

Silva, Laura A; Maimoni-Rodella, Rita C S; Rossi, Marcelo N

2007-01-01

157

The rheological properties of the seed coat mucilage of Capsella bursa-pastoris L. Medik. (shepherd's purse).  

PubMed

The outer surface of myxospermous seed coats contains mucilage which absorbs large amounts of water relative to its dry weight. Ecologically, the seed mucilage can affect seed germination and dormancy. Upon hydration, a large proportion of the seed mucilage is lost to the soil and the physics of soil-seed mucilage interactions has not been assessed. Towards that end, the dynamic rheological properties of mucilage extracted from Capsella bursa-pastoris L. Medik. (shepherd's purse) seeds were assessed as a function of mucilage concentration (1-10% [w/w]), temperature (0-80°C) and shear frequency (0.1-100 rad s-1). The seed mucilage was shear thinning and was classified as a highly viscous "weak gel". The relationship between the viscoelastic parameters (viscosity, ?*, storage and loss modulus, G' and G?, yield and flow stresses, ?y and ?f) and mucilage concentration were well fitted by power law models. The values of ?*, G' and G? increased as temperature increased above 40°C and were also slightly frequency dependent. The shepherd's purse seed mucilage is more viscous than that from other plant parts, such as fruits and roots. These properties highlight the possibility that seed mucilage may affect soil conditions and therefore present an additional facilitative ecological role (beyond that already reported, which directly affect seed biology); and this is discussed. PMID:23619153

Deng, Wenni; Iannetta, Pietro P M; Hallett, Paul D; Toorop, Peter E; Squire, Geoffrey R; Jeng, Dong-Sheng

2013-01-01

158

Simulation of free-electron lasers seeded with broadband radiation  

SciTech Connect

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.

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

2011-03-10

159

On subset seeds for protein alignment.  

PubMed

We apply the concept of subset seeds to similarity search in protein sequences. The main question studied is the design of efficient seed alphabets to construct seeds with optimal sensitivity/selectivity trade-offs. We propose several different design methods and use them to construct several alphabets. We then perform a comparative analysis of seeds built over those alphabets and compare them with the standard Blastp seeding method, as well as with the family of vector seeds. While the formalism of subset seeds is less expressive (but less costly to implement) than the cumulative principle used in Blastp and vector seeds, our seeds show a similar or even better performance than Blastp on Bernoulli models of proteins compatible with the common BLOSUM62 matrix. Finally, we perform a large-scale benchmarking of our seeds against several main databases of protein alignments. Here again, the results show a comparable or better performance of our seeds versus Blastp. PMID:19644175

Roytberg, Mikhail; Gambin, Anna; Noé, Laurent; Lasota, Slawomir; Furletova, Eugenia; Szczurek, Ewa; Kucherov, Gregory

2009-01-01

160

Seed storage oil mobilization.  

PubMed

Storage oil mobilization starts with the onset of seed germination. Oil bodies packed with triacylglycerol (TAG) exist in close proximity with glyoxysomes, the single membrane-bound organelles that house most of the biochemical machinery required to convert fatty acids derived from TAG to 4-carbon compounds. The 4-carbon compounds in turn are converted to soluble sugars that are used to fuel seedling growth. Biochemical analysis over the last 50 years has identified the main pathways involved in this process, including beta-oxidation, the glyoxylate cycle, and gluconeogenesis. In the last few years molecular genetic dissection of the overall process in the model oilseed species Arabidopsis has provided new insight into its complexity, particularly with respect to the specific role played by individual enzymatic steps and the subcellular compartmentalization of the glyoxylate cycle. Both abscisic acid (ABA) and sugars inhibit storage oil mobilization and a substantial degree of the control appears to operate at the transcriptional level. PMID:18444898

Graham, Ian A

2008-01-01

161

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

PubMed

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

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

2013-01-01

162

Implications of nonrandom seed abscission and global stilling for migration of wind-dispersed plant species.  

PubMed

Migration of plant populations is a potential survival response to climate change that depends critically on seed dispersal. Biological and physical factors determine dispersal and migration of wind-dispersed species. Recent field and wind tunnel studies demonstrate biological adaptations that bias seed release toward conditions of higher wind velocity, promoting longer dispersal distances and faster migration. However, another suite of international studies also recently highlighted a global decrease in near-surface wind speeds, or 'global stilling'. This study assessed the implications of both factors on potential plant population migration rates, using a mechanistic modeling framework. Nonrandom abscission was investigated using models of three seed release mechanisms: (i) a simple drag model; (ii) a seed deflection model; and (iii) a 'wear and tear' model. The models generated a single functional relationship between the frequency of seed release and statistics of the near-surface wind environment, independent of the abscission mechanism. An Inertial-Particle, Coupled Eulerian-Lagrangian Closure model (IP-CELC) was used to investigate abscission effects on seed dispersal kernels and plant population migration rates under contemporary and potential future wind conditions (based on reported global stilling trends). The results confirm that nonrandom seed abscission increased dispersal distances, particularly for light seeds. The increases were mitigated by two physical feedbacks: (i) although nonrandom abscission increased the initial acceleration of seeds from rest, the sensitivity of the seed dispersal to this initial condition declined as the wind speed increased; and (ii) while nonrandom abscission increased the mean dispersal length, it reduced the kurtosis of seasonal dispersal kernels, and thus the chance of long-distance dispersal. Wind stilling greatly reduced the modeled migration rates under biased seed release conditions. Thus, species that require high wind velocities for seed abscission could experience threshold-like reductions in dispersal and migration potential if near-surface wind speeds continue to decline. PMID:23505130

Thompson, Sally E; Katul, Gabriel G

2013-06-01

163

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

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 term research and development studies and with a large amount of expense and causes the return of expenses to take a long time, if ever. PMID:19093496

Tanrivermi?, Harun; Akdo?an, Ilyas

2007-12-15

164

Topic in Depth - Cloud Seeding  

NSDL National Science Digital Library

This Topic in Depth is about cloud seeding, a type of weather modification in which substances, such as silver iodide or dry ice, are added to the air in order to produce changes in the weather. Cloud seeding is most commonly used to increase precipitation, but may also be used to suppress certain weather patterns as well, such as hail and high winds. While there is some controversy about whether or not cloud seeding actually does produce more precipitation, it can be a highly useful tool for areas that have very arid conditions and need additional rainfall to help produce more viable crops and minimize drought-like conditions.

2010-09-09

165

[Effect of decimeter polarized electromagnetic radiation on germinating capacity of seeds].  

PubMed

The effect of a polarization structure of electromagnetic radiation on the germinating capacity of seeds of such weeds as Green foxtail (Setaria viridis) and Green amaranth (Amaranthus retroflexus) has been studied. Seeds have been exposed to impulse electromagnetic radiation in a frequency of 896 MHz with linear, elliptical right-handed and elliptical left-handed polarizations at different power flux density levels. It is determined that the effect of the right-handed polarized electromagnetic radiation increases and the influence of the left-handed polarized one reduces the germinating capacity of seeds compared to the effect of the linearly polarized electromagnetic radiation. It is shown that the seeds have an amplitude polarization selectivity as evinced by the major effect of the right-handed polarized radiation on seeds. An electrodynamic model as the right-handed elliptically polarized antenna with the given quantity of the ellipticity of polarization is suggested to use in description of this selectivity. PMID:24455890

Polevik, N D

2013-01-01

166

Tumbling For Seed Cleaning and Conditioning1  

Microsoft Academic Search

Small rock tumblers can be used to clean and condition seeds both in an aqueous and a dry mode. During the process, grit and gravel remove fruit pulp and abrade seed coats. Wet tumbling of seed aids imbibition, leaches water-soluble germination inhibitors, and may partially substitute for cold stratification for some shrub seed lots.

David Dreesen

167

Seed Production and Germinability of Cucurbit Crops  

Microsoft Academic Search

Cucurbit crops are mostly produced for their immature or mature fruits. However, a relatively high proportion of cucurbit fields are destined for seed production, either for seed consumption or for propagation material. Production of cucurbits for seed consumption (as a snack food) is very popular in some parts of the globe and almost unknown in others. Open-pollinated cultivars (inexpensive seeds)

Haim Nerson

168

Improvements on a Reliable Oak Seed Trap.  

National Technical Information Service (NTIS)

The need for seed trap longevity, capture of heavy seed, and protection from predation in several forest types for long-term studies of seed production prompted seed trap design improvements. Critical improvements were achieved by painting the trap with a...

C. N. Phillips M. K. Burke T. B. Hunnicutt

1995-01-01

169

7 CFR 201.50 - Weed seed.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Weed seed. 201.50 Section 201.50 ...Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed...

2009-01-01

170

7 CFR 201.50 - Weed seed.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Weed seed. 201.50 Section 201.50 ...Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed...

2010-01-01

171

Laser Seeding of the Storage-Ring Microbunching Instability for High-Power Coherent Terahertz Radiation  

NASA Astrophysics Data System (ADS)

We report the first observation of laser seeding of the storage-ring microbunching instability. Above a threshold bunch current, the interaction of the beam and its radiation results in a coherent instability, observed as a series of stochastic bursts of coherent synchrotron radiation (CSR) at terahertz frequencies initiated by fluctuations in the beam density. We have observed that this effect can be seeded by imprinting an initial density modulation on the beam by means of laser “slicing.” In such a situation, most of the bursts of CSR become synchronous with the pulses of the modulating laser and their average intensity scales exponentially with the current per bunch. We present detailed experimental observations of the seeding effect and a model of the phenomenon. This seeding mechanism also creates potential applications as a high-power source of CSR at terahertz frequencies.

Byrd, J. M.; Hao, Z.; Martin, M. C.; Robin, D. S.; Sannibale, F.; Schoenlein, R. W.; Zholents, A. A.; Zolotorev, M. S.

2006-08-01

172

Seed weight patterns of Acacia tortilis from seven seed provenances across Botswana  

Microsoft Academic Search

Laboratory-based seed storage systems have been devel- oped as an alternative to in situ conservation for indigen- ous woody plant species. However, interactions between seed quality and environmental variables must be known for each species prior to seed collection, storage and sowing to ensure effective conservation. This study investigated Acacia tortilis seed weight\\/quality patterns across seven Botswana seed provenances in

N. M. Moleele; M. S. Reed; L. Motoma; O. Seabe

2005-01-01

173

Getting Acquainted with a Seed  

NSDL National Science Digital Library

Description: In this activity students become acquainted with the anatomy and biology of seeds. They will use lenses and scales and make drawings to scale. Students will measure and calculate magnifications and they will begin to understand relationships among these. They will organize and summarize their data and, as they do so, they will be developing the understanding and skills needed to undertake more detailed investigations on the biology and reproduction of Fast Plants.Learning ObjectivesThis activity is designed to strengthen students' observational and quantitative skills. In participating in this activity students will:- learn to use magnifying lenses, microscopes and dissecting tools for detailed observation; - measure scales with rulers; - draw to scale, with accuracy and precision to understand scale and magnification; - learn features of the external anatomy of seeds that are associated with certain features of the internal anatomy of seeds; and - estimate the amount of water required to be taken up by seeds in order to initiate germination.

Program, The W.

174

Biotechnology of oil seed crops  

SciTech Connect

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.

James, A.T.

1985-02-01

175

Hygroscopic Seeding of Convective Clouds.  

National Technical Information Service (NTIS)

This report summarizes the results of over 10,000 separate computer runs investigating the possible effects of hygroscopic seeding on the time or location of the initial development of precipitation in convective clouds. This study suggests that hygroscop...

D. B. Johnson

1980-01-01

176

Autoradiography for iodine-125 seeds  

SciTech Connect

To study the interior design of model 6702 and 6711 iodine-125 seeds, contact autoradiographs were performed using mammography film. Improved resolution was obtained using a pin-hole camera with a hole of 0.1 mm [times] 0.1 mm. With these techniques, qualitative determination of the relative activity distribution within each seed was possible. The number of the activated resin spheres and the positions of the centers of these spheres can be exactly determined. A model calculation shows that variations in the arrangement of the activated spheres within a seed have a moderate influence on the dose distribution at source distances below 10 mm. Knowing the exact source configuration may be useful when comparing dose calculations with measured data for model 6702 [sup 125]I seeds which are currently employed in ophthalmic plaque and implant therapy of other tumors. 16 refs., 5 figs., 2 tabs.

Alberti, W.; Divoux, S. (Alfried Krupp Krankenhaus, Essen (Germany)); Pothmann, B.; Tabor, P. (Universitaetsklinikum, Essen (Germany)); Hermann, K.P.; Harder, D. (Universitaet Goettingen (Germany))

1993-04-02

177

Selectively Nucleated Lateral Crystallization of Lead Zirconate Titanate Thin Films Using Titanium Island Seed Layer  

Microsoft Academic Search

We have investigated the selectively nucleated lateral crystallization (SNLC) of lead zirconate titanate (PZT) thin film using a titanium seed. The titanium island seed layer was formed on Pt(200 nm)\\/SiO2(500 nm)\\/Si by radio frequency magnetron sputtering and lift-off process at room temperature. Selectively nucleated lateral crystallization happened at 570°C and a rectangular array of PZT single grains was formed after

JONG-IN YUN; NAM-KYU SONG; SEUNG-KI JOO

2004-01-01

178

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

Microsoft Academic Search

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

Randal L. Schmitt; Larry A. Rahn

1986-01-01

179

Economic Evaluation of Soybean Fungicide Seed Treatments  

Microsoft Academic Search

ing a more informed seed treatment decision before planting.Also,sinceseedcostandassociatedtechnology The effects of fungicide seed treatments on seeding rate, location, fees have made seed cost a greater percentage of op- simulated rainfall at emergence, time of planting, and seed quality erating costs (Lambert and Lowenberg-DeBoer, 2003), were analyzed for soybean (Glycine max (L.) Merr.) in this study. Variation in plant emergence

Paul Scott Poag; Michael Popp; John Rupe; Bruce Dixon; Craig Rothrock; Carol Boger

2005-01-01

180

The seed proteome web portal.  

PubMed

The Seed Proteome Web Portal (SPWP; http://www.seed-proteome.com/) gives access to information both on quantitative seed proteomic data and on seed-related protocols. Firstly, the SPWP provides access to the 475 different Arabidopsis seed proteins annotated from two dimensional electrophoresis (2DE) maps. Quantitative data are available for each protein according to their accumulation profile during the germination process. These proteins can be retrieved either in list format or directly on scanned 2DE maps. These proteomic data reveal that 40% of seed proteins maintain a stable abundance over germination, up to radicle protrusion. During sensu stricto germination (24?h upon imbibition) about 50% of the proteins display quantitative variations, exhibiting an increased abundance (35%) or a decreasing abundance (15%). Moreover, during radicle protrusion (24-48?h upon imbibition), 41% proteins display quantitative variations with an increased (23%) or a decreasing abundance (18%). In addition, an analysis of the seed proteome revealed the importance of protein post-translational modifications as demonstrated by the poor correlation (r(2)?=?0.29) between the theoretical (predicted from Arabidopsis genome) and the observed protein isoelectric points. Secondly, the SPWP is a relevant technical resource for protocols specifically dedicated to Arabidopsis seed proteome studies. Concerning 2D electrophoresis, the user can find efficient procedures for sample preparation, electrophoresis coupled with gel analysis, and protein identification by mass spectrometry, which we have routinely used during the last 12?years. Particular applications such as the detection of oxidized proteins or de novo synthesized proteins radiolabeled by [(35)S]-methionine are also given in great details. Future developments of this portal will include proteomic data from studies such as dormancy release and protein turnover through de novo protein synthesis analyses during germination. PMID:22701460

Galland, Marc; Job, Dominique; Rajjou, Loïc

2012-01-01

181

The seeds always know best  

Microsoft Academic Search

The New Zealand woody plant flora differs from those of temperate Northern Hemisphere regions by having: a very high proportion (70% cf. 17-47%) of tree species (but lower proportions of shrubs and vines) with fleshy fruit; a relatively low proportion of seeds with overwinter dormancy; and relatively few species that form long-term (i.e., 1 year or longer) seed banks. These

Colin J. Burrows

1994-01-01

182

Drying kinetics of grape seeds  

Microsoft Academic Search

Drying of grape seeds representing waste products from white wine processing (Riesling), red wine processing (Cab Franc), and juice processing (Concord) was studied at 40, 50, and 60°C and constant air velocity of 1.5m\\/s. Equilibrium moisture content had a significant effect on the normalized drying curve and was determined for each grape seed at each drying temperature. Effective moisture diffusivity

John S. Roberts; David R. Kidd; Olga Padilla-Zakour

2008-01-01

183

Seed dormancy and ABA signaling  

PubMed Central

The seed is an important organ in higher plants, it is an important organ for plant survival and species dispersion. The transition between seed dormancy and germination represents a critical stage in the plant life cycle and it is an important ecological and commercial trait. A dynamic balance of synthesis and catabolism of two antagonistic hormones, abscisic acid (ABA) and giberellins (GAs), controls the equilibrium between seed dormancy and germination. Embryonic ABA plays a central role in induction and maintenance of seed dormancy and also inhibits the transition from embryonic to germination growth. Therefore, the ABA metabolism must be highly regulated at both temporal and spatial levels during phase of dessication tolerance. On the other hand, the ABA levels do not depend exclusively on the seeds because sometimes it becomes a strong sink and imports it from the roots and rhizosphere through the xylem and/or phloem. These events are discussed in depth here. Likewise, the role of some recently characterized genes belonging to seeds of woody species and related to ABA signaling are also included. Finally, although four possible ABA receptors have been reported, not much is known about how they mediate ABA signaling transduction. However, new publications seem to show that almost all these receptors lack several properties to consider them as such.

del Carmen Rodriguez-Gacio, Maria; Matilla-Vazquez, Miguel A

2009-01-01

184

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

NASA Astrophysics Data System (ADS)

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 thermal noise is also developed to study SBS suppression under phase modulated pump conditions. The SBS suppression is characterized for several phase modulation schemes. It is found that the SBS suppression for a white-noise phase modulation (WNS) which broadens the pump spectrum, depends significantly on the length of fiber and only in the long fiber limit follows the often quoted threshold enhancement formula of Pth = P0 (1+Deltanu/Deltanu B) where P0, Deltanu and Deltanu B describe the SBS threshold of the single-frequency case, the effective linewidth of the pump, and the spontaneous Brillouin linewidth respectively. In addition, the SBS threshold is characterized as a function of modulation amplitude and frequency for a single-sinusoidal phase modulation scheme.

Zeringue, Clint Matthew

185

Echo-Enabled Harmonic Generation for Seeded FELs  

SciTech Connect

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.

Stupakov, G.; /SLAC

2011-05-19

186

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

Code of Federal Regulations, 2010 CFR

...potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading 1005.10., HTSUS, shall be made at the time of entry. Such classification shall be...

2010-04-01

187

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

Code of Federal Regulations, 2010 CFR

...potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading 1005.10., HTSUS, shall be made at the time of entry. Such classification shall be...

2009-04-01

188

The Seed Challenge - `How many seeds can you get from a single seed?  

NSDL National Science Digital Library

A 23-page PDF file (644 KB) with a complete set of activities for elementary students (can also work with middle level) to learn about the life cycle of flowering plants. Students predict how many seeds their Fast Plant will produce and engage in planting, growing, observing doing supporting learning activities to understand the life cycle.Carolina Biological sells a kit to accompany this activity for a class of 32 students, containing the seeds and planting materials. Alternatively, the activity can be taught using seeds from a packet of Standard Wisconsin Fast Plants (or seeds from Fast Plants you grow yourself) and your own potting mix and growing system.A 24-hour fluorescent light source is needed for this activity.

Program, The W.

189

Can Soil Seed Banks Serve as Genetic Memory? A Study of Three Species with Contrasting Life History Strategies  

PubMed Central

We attempted to confirm that seed banks can be viewed as an important genetic reservoir by testing the hypothesis that standing (aboveground) plants represent a nonrandom sample of the seed bank. We sampled multilocus allozyme genotypes from three species with different life history strategies: Amaranthus retroflexus, Carduus acanthoides, Pastinaca sativa. In four populations of each species we analysed the extent to which allele and genotype frequencies vary in consecutive life history stages including the summer seed bank, which has been overlooked up to now. We compared the winter seed bank (i.e., seeds collected before the spring germination peak), seedlings, rosettes, the summer seed bank (i.e., seeds collected after the spring germination peak) and fruiting plants. We found that: (1) All three species partitioned most of their genetic diversity within life history stages and less among stages within populations and among populations. (2) All genetic diversity parameters, except for allele frequencies, were similar among all life history stages across all populations in different species. (3) There were differences in allele frequencies among life history stages at all localities in Amaranthus retroflexus and at three localities in both Carduus acanthoides and Pastinaca sativa. (4) Allele frequencies did not differ between the winter and summer seed bank in most Carduus acanthoides and Pastinaca sativa populations, but there was a marked difference in Amaranthus retroflexus. In conclusion, we have shown that the summer seed bank is not genetically depleted by spring germination and that a majority of genetic diversity remains in the soil through summer. We suggest that seed banks in the species investigated play an important role by maintaining genetic diversity sufficient for recovery rather than by accumulating new genetic diversity at each locality.

Mandak, Bohumil; Zakravsky, Petr; Mahelka, Vaclav; Plackova, Ivana

2012-01-01

190

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

191

Laser Phase Errors in Seeded FELs  

SciTech Connect

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.

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

2012-03-28

192

Osmotic priming of true potato seed: Effects of seed age  

Microsoft Academic Search

Summary  The effects on germination and early seedling growth of presowing true potato seed in water or gibberellic acid (GA) at 1500\\u000a ppm and of priming in ?1.0, ?1.25 and ?1.5 MPa solutions of KNO3+K3PO4 were studied using 30, 18, 6 and 3\\/4 month-old seed. The influence of light during presowing on the effectiveness of treatments\\u000a was also investigated.\\u000a \\u000a Overall, priming

N. Pallais

1989-01-01

193

Seed Rain and Seed Bank Reveal that Seed Limitation Strongly Influences Plant Community Assembly in Grasslands  

PubMed Central

Dispersal is an important factor in plant community assembly, but assembly studies seldom include information on actual dispersal into communities, i.e. the local propagule pool. The aim of this study was to determine which factors influence plant community assembly by focusing on two phases of the assembly process: the dispersal phase and the establishment phase. At 12 study sites in grazed ex-arable fields in Sweden the local plant community was determined and in a 100-m radius around the centre of each site, the regional species pool was measured. The local seed bank and the seed rain was explored to estimate the local propagule pool. Trait-based models were then applied to investigate if species traits (height, seed mass, clonal abilities, specific leaf area and dispersal method) and regional abundance influenced which species from the regional species pool, dispersed to the local community (dispersal phase) and which established (establishment phase). Filtering of species during the dispersal phase indicates the effect of seed limitation while filtering during the establishment phase indicates microsite limitation. On average 36% of the regional species pool dispersed to the local sites and of those 78% did establish. Species with enhanced dispersal abilities, e.g. higher regional abundance, smaller seeds and dispersed by cattle, were more likely to disperse to the sites than other species. At half the sites, dispersal was influenced by species height. Species establishment was however mainly unlinked to the traits included in this study. This study underlines the importance of seed limitation in local plant community assembly. It also suggests that without information on species dispersal into a site, it is difficult to distinguish between the influence of dispersal and establishment abilities, and thus seed and microsite limitation, as both can be linked to the same trait.

Marteinsdottir, Bryndis

2014-01-01

194

Effect of Resting Patterns of Tamarins (Saguinus fuscicollis and Saguinus mystax) on the Spatial Distribution of Seeds and Seedling Recruitment  

PubMed Central

The spatial distributions of dispersed seeds have important evolutionary consequences for plants. Repeated defecations in sites frequently used by seed dispersers can result in high seed concentrations. We observed the resting behavior of a mixed-species group of tamarins in Peru and recorded the occurrence of seed dispersal (over 8 mo) and seed fate (over 11–22 mo) to determine whether the location and use of resting sites influenced the spatial distribution of dispersed seeds and seedlings. The tamarins rested mostly on trees (Saguinus fuscicollis: 60.6%, S. mystax: 89.2%) and dead trunks (S. fuscicollis: 24.4%) and used 61% of their resting sites repeatedly. During both the dry and wet seasons, tamarins dispersed significantly more seeds within resting areas (0.00662 and 0.00424 seeds/m2, respectively) than outside them (0.00141 and 0.00181 seeds/m2). Seed survival and seedling recruitment did not differ significantly between resting and other areas, resulting in a higher seedling concentration around the resting sites. Seed density did not increase with the duration or the frequency of use of the resting sites but did increase when we pooled the seasonal resting sites together in 50 m?×?50 m quadrats, ultimately causing a clumped distribution of dispersed seeds. The use of resting sites in secondary forest, particularly during the dry season, allows the creation of seedling recruitment centers for species coming from the primary forest. Our findings show that tamarin resting behavior affects the spatial distribution of dispersed seeds and seedlings, and their resting sites play an important role in plant diversity maintenance and facilitate forest regeneration in degraded areas.

Culot, Laurence; Huynen, Marie-Claude; Heymann, Eckhard W.

2010-01-01

195

Unique Method for Generating Design Earthquake Time History Seeds  

SciTech Connect

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.

R. E. Spears

2008-07-01

196

Seed Mucilage Improves Seedling Emergence of a Sand Desert Shrub  

PubMed Central

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.

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

2012-01-01

197

Smoke signals and seed dormancy  

PubMed Central

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.

Waters, Mark T; Nelson, David C

2011-01-01

198

Multiple frequency optical mixer and demultiplexer and apparatus for remote sensing  

NASA Technical Reports Server (NTRS)

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.

Chen, Jeffrey R. (Inventor)

2010-01-01

199

Scheduling Fall Seedings for Cold-Climate Revegetation.  

National Technical Information Service (NTIS)

Revegetating construction sites in the fall requires the scheduling of seeding and mulching for either permanent or dormant seedings. Dormant seedings must be late enough in the fall to prevent germination, while permanent seedings must be early enough to...

A. J. Palazzo C. H. Racine R. N. Bailey

1990-01-01

200

SEEDS Moving Group Status Update  

NASA Technical Reports Server (NTRS)

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.

McElwain, Michael

2011-01-01

201

Electromagnetic Treatment of Loblolly Pine Seeds.  

National Technical Information Service (NTIS)

Loblolly pine (Pinus taeda L.) seeds were exposed to an electromagnetic radiation treatment (Energy Transfer Process, marketed by the Energy Transfer Corporation), and the effects of the treatments on seed germination, seedling development, disease resist...

J. P. Barnett S. L. Krugman

1989-01-01

202

Recommended Amounts of Nuts, seeds, and soy  

Cancer.gov

Recommended Amounts of Nuts, seeds, and soy Table B14. Nuts, seeds, and soy: Estimated percentage of persons below, at, or above recommendation1 Age (years) N Mean (SE) % with intake below recommendation (SE) % with intake meeting recommendation (SE) %

203

Breaking seed coat dormancy of Acacia nilotica seeds under simulated natural habitat conditions in Sudan  

Microsoft Academic Search

This study attempted to break the seed coat dormancy of Acacia nilotica, a riverine tree species, by simulating natural conditions. The effects of extended water soaking, soil burial and shade placement on seeds and pods were studied. Pods, clean-seeds and unclean-seeds were soaked in water for periods up to 24 weeks in two sites with or without forest soil. The

ESSAM I. WARRAG; MASHAIR A. ELTIGANI

204

MHD heat and seed recovery technology project  

NASA Astrophysics Data System (ADS)

Heat and Seed Recovery Technology Project is discussed, including NOx behavior in the radiant boiler and secondary combustor, radiant boiler design to meet the multiple requirements of steam generation, NOx decomposition, and seed-slag separating, effects of solid or liquid seed deposits on heat transfer and gas flow in the steam and air heaters, formation, growth, and deposition of seed-slag particles, character of the combustion gas effluents, and the corrosion and erosion of ceramic and metallic materials of construction.

Petrick, M.; Johnson, T. R.

1980-08-01

205

Study on the seed laser phase error multiplication in seeded free electron lasers  

NASA Astrophysics Data System (ADS)

Seeded free-electron lasers (FELs) hold a great promise for generating high brilliant radiation with a narrow bandwidth. However, it has been pointed out that the initial seed laser noise will be amplified in the harmonic up-conversion process, which may degrade the output radiation pulse quality of a seeded FEL. In this paper, theoretical and simulation studies of seeded FEL schemes with seed laser imperfections are presented. It is found that the slippage effect in the modulator will slow down the multiplication process of the seed laser phase error, which may aid in the production of transform-limited short-wavelength pulses for seeded FELs.

Wang, Guanglei; Feng, Chao; Zhang, Tong; Wang, Dong; Deng, Haixiao

2014-02-01

206

Patterns of allozymic variation within calluna vulgaris populations at seed bank and adult stages  

PubMed

We investigated the spatial genetic structure within and between two plots of Calluna vulgaris and the extent to which the soil seed bank differed genetically from adults at seven allozyme loci. Averaged over the two plots, the seed bank and adult populations contained very similar levels of genetic diversity. Moreover, seeds contained in a single soil core (100 cm3) exhibited similar mean allozyme diversity to the surrounding adult population, indicating that the seed bank preserves genetic diversity at a very local scale. Few differences in allelic frequencies were found between the seed bank and its surrounding adult population in each plot. Mean GST indicated a lack of differentiation between the two plots at adult (GST = 0.008) and seed bank (GST = 0.002) stages. Low interplot differentiation is consistent with the outcrossing mating system of the population (tm = 0.91 in one plot) and its history of human disturbance. In contrast, spatial autocorrelation analysis of adults indicated a genetic structure at a very local scale, with positive autocorrelation for all alleles below 2 m in one plot and with a pattern of positive autocorrelation below 8 m in the two plots. Current limitation to seed dispersal rather than spatial extension of clones is thought to be responsible for local genetic structure. PMID:10383662

Mahy; Vekemans; Jacquemart

1999-04-01

207

Storage Requirements for Sugar Maple Seeds.  

National Technical Information Service (NTIS)

Sugar maple seeds, collected from three trees in northern Vermont, were stored at four temperatures (18, 7, 2 and -10C) in combination with four seed moisture contents (35, 25, 17, and 10 percent). Seed moisture content and storage temperature significant...

C. M. Carl H. W. Yawney

1974-01-01

208

Involvement of ethylene in seed physiology  

Microsoft Academic Search

The seed, the organ by which higher plants perpetuate themselves, is programmed to survive after being dispersed from the mother plant until establishing a photosynthetically competent seedling. Seed dormancy, conceived as the temporary failure of an intact viable seed to complete germination under favourable conditions, is developed during the last period of embryogenesis and prevents germination during periods unfavourable to

A. J. Matilla; M. A. Matilla-Vázquez

2008-01-01

209

Nitric oxide reduces seed dormancy in Arabidopsis  

Microsoft Academic Search

Dormancy is a property of many mature seeds, and experimentation over the past century has identified numerous chemical treatments that will reduce seed dormancy. Nitrogen-containing compounds including nitrate, nitrite, and cyanide break seed dormancy in a range of species. Experiments are described here that were carried out to further our understanding of the mechanism whereby these and other compounds, such

Paul C. Bethke; Igor G. L. Libourel; Russell L. Jones

2006-01-01

210

46 CFR 148.310 - Seed cake.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Seed cake. 148.310 Section 148.310 Shipping...Certain Materials § 148.310 Seed cake. (a) This part does not apply to...combined. (c) Before loading, the seed cake must be aged per the instructions of...

2013-10-01

211

The composition of mowrah-seed oil  

Microsoft Academic Search

Mowrah-seed oil or Mowrah butter is derived from the seeds of the Bassia latifolia, a tree widely distributed in India. It is an important food stuff in the northwest provinces of India: it is also used for candle and soap making, and medicinally as an ointment. The seeds contain about fifty per cent of oil. The oil is decidedly yellow,

Augustus H. Gill; Champak C. Shah

1925-01-01

212

7 CFR 947.12 - Seed potatoes.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Seed potatoes. 947.12 Section 947.12 Agriculture...DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN MODOC AND SISKIYOU COUNTIES...Handling Definitions § 947.12 Seed potatoes. Seed potatoes means and...

2009-01-01

213

Seed Scarification Requirement in Doum (Hyphaene thebaica Mart.)  

Microsoft Academic Search

Seed dormancy is a means to allow seeds to initiate germination when conditions are normally favorable for germination and survival of the seedlings. Dormancy can be regulated by the environment or by the seed itself. The seed dormancy may be due to unfavorable environmental conditions or sometimes, some seeds may not germinate because of some inhibitory factor of the seed

Mohammed A. Al-Fredan; Yusef S. S. Ali

2008-01-01

214

Seed Coat Dormancy in Two Species of Grevillea(Proteaceae)  

Microsoft Academic Search

The role played by the seed coat in seed dormancy of Grevillea linearifolia(Cav.) Druce and G. wilsonii(A. Cunn.) was tested by a series of manipulations in which the seed coat was dissected and removed, dissected and returned to the decoated seed, or dissected, removed and given a heat shock, and returned to the decoated seed. Germination of intact seeds of

E. Charles Morris; Anle Tieu; Kingsley Dixon

2000-01-01

215

Molecular Aspects of Seed Dormancy  

Microsoft Academic Search

Seed dormancy provides a mechanism for plants to delay germina- tion until conditions are optimal for survival of the next generation. Dormancy release is regulated by a combination of environmental and endogenous signals with both synergistic and competing effects. Molecular studies of dormancy have correlated changes in transcrip- tomes, proteomes, and hormone levels with dormancy states ranging from deep primary

Ruth Finkelstein; Wendy Reeves; Tohru Ariizumi; Camille Steber

2008-01-01

216

Noise Amplification in HGHG Seeding  

SciTech Connect

An essential element of seeded FEL based on high-gain harmonic generation (HGHG) or echo-enabled harmonic generation (EEHG) is an undulator-modulator, in which interaction with a laser beam modulates the beam energy. We study how the interaction of electrons in this undulator-modulator changes the noise properties of the beam.

Stupakov, Gennady

2010-08-25

217

Climate Kids: Make Seed Paper  

NSDL National Science Digital Library

The recycled paper produced from the instructions provided contains an additional component - wildflower seeds. The entire paper disc can be planted; the sprouting of the flowers can be observed and analyzed. The Climate Kids website is a NASA education resource featuring articles, videos, images and games focused on the science of climate change.

218

Polar constituents of celery seed  

Microsoft Academic Search

From the water-soluble portion of the methanol extract of celery seed (fruit of Apium graveolens L.) five sesquiterpenoid glucosides (celerioside A–E) and three phthalide glycosides (celephtalide A–C) were isolated together with six aromatic compound glucosides, two norcarotenoid glucosides and a lignan glucoside. Their structures were determined by spectral investigations.

Junichi Kitajima; Toru Ishikawa; Mitsuru Satoh

2003-01-01

219

Carbohydrates from Sophora flavescens seeds  

Microsoft Academic Search

Sophora flavescens Soland (Leguminosae) is a medicinal plant, the roots of which are used widely in Tibetan medicine to treat infectious diseases and diseases of the gastro-intestinal tract and nervous system [1]. The chemical composition of i ts roots [2] and seeds of Leguminosae plants have been investigated for the presence of galactomannans. Information about the compounds contained in S.

D. N. Olennikov; L. M. Tankhaeva; D. V. Sandanov

2007-01-01

220

Sowing the Seeds of Neuroscience  

NSDL National Science Digital Library

Sowing the Seeds of Neuroscience seeks to increase student interest and understanding of neuroscience through simple, safe lab investigations using plants. The site contains 8 laboratory investigations exploring properties of compounds found in plants and their effect on the behavior and growth of invertebrates. The site also provides general neuroscience and medicinal plant information.

Chudler, Eric

2014-04-04

221

Diversity of plant oil seed-associated fungi isolated from seven oil-bearing seeds and their potential for the production of lipolytic enzymes.  

PubMed

Commercial oil-yielding seeds (castor, coconut, neem, peanut, pongamia, rubber and sesame) were collected from different places in the state of Tamil Nadu (India) from which 1279 endophytic fungi were isolated. The oil-bearing seeds exhibited rich fungal diversity. High Shannon-Index H' was observed with pongamia seeds (2.847) while a low Index occurred for coconut kernel-associated mycoflora (1.018). Maximum Colonization Frequency (%) was observed for Lasiodiplodia theobromae (176). Dominance Index (expressed in terms of the Simpson's Index D) was high (0.581) for coconut kernel-associated fungi, and low for pongamia seed-borne fungi. Species Richness (Chao) of the fungal isolates was high (47.09) in the case of neem seeds, and low (16.6) for peanut seeds. All 1279 fungal isolates were screened for lipolytic activity employing a zymogram method using Tween-20 in agar. Forty isolates showed strong lipolytic activity, and were morphologically identified as belonging to 19 taxa (Alternaria, Aspergillus, Chalaropsis, Cladosporium, Colletotrichum, Curvularia, Drechslera, Fusarium, Lasiodiplodia, Mucor, Penicillium, Pestalotiopsis, Phoma, Phomopsis, Phyllosticta, Rhizopus, Sclerotinia, Stachybotrys and Trichoderma). These isolates also exhibited amylolytic, proteolytic and cellulolytic activities. Five fungal isolates (Aspergillus niger, Chalaropsis thielavioides, Colletotrichum gloeosporioides, Lasiodiplodia theobromae and Phoma glomerata) exhibited highest lipase activities, and the best producer was Lasiodiplodia theobromae (108 U/mL), which was characterized by genomic sequence analysis of the ITS region of 18S rDNA. PMID:22806781

Venkatesagowda, Balaji; Ponugupaty, Ebenezer; Barbosa, Aneli M; Dekker, Robert F H

2012-01-01

222

Effects of APETALA2 on embryo, endosperm, and seed coat development determine seed size in Arabidopsis  

Microsoft Academic Search

Arabidopsis APETALA2 (AP2) controls seed mass maternally, with ap2 mutants producing larger seeds than wild type. Here, we show that AP2 influences development of the three major seed compartments:\\u000a embryo, endosperm, and seed coat. AP2 appears to have a significant effect on endosperm development. ap2 mutant seeds undergo an extended period of rapid endosperm growth early in development relative to

Masa-aki Ohto; Sandra K. Floyd; Robert L. Fischer; Robert B. Goldberg; John J. Harada

2009-01-01

223

Aerial seed storage in Melaleuca ericifolia Sm. (Swamp Paperbark): environmental triggers for seed release  

Microsoft Academic Search

Aerial seed banks are potentially the main source of sexual recruitment for woody wetland plants. Whilst the importance of\\u000a soil seed banks for the persistence and recruitment of wetland plants has been examined in many studies, the role of aerial\\u000a seed banks has been largely neglected. We used seed traps and the seedling emergence technique to quantify the seed rain

Sheila Hamilton-Brown; Paul I. Boon; Elisa Raulings; Kay Morris; Randall Robinson

2009-01-01

224

Quantitative imaging of oil storage in developing crop seeds.  

PubMed

In this article, we present a tool which allows the rapid and non-invasive detection and quantitative visualization of lipid in living seeds at a variety of stages using frequency-selected magnetic resonance imaging. The method provides quantitative lipid maps with a resolution close to the cellular level (in-plane 31 microm x 31 microm). The reliability of the method was demonstrated using two contrasting subjects: the barley grain (monocot, 2% oil, highly compartmentalized) and the soybean grain (dicot, 20% oil, economically important oilseed). Steep gradients in local oil storage were defined at the organ- and tissue-specific scales. These gradients were closely coordinated with tissue differentiation and seed maturation, as revealed by electron microscopy and biochemical and gene expression analysis. The method can be used to elucidate similar oil accumulation processes in different tissues/organs, as well as to follow the fate of storage lipids during deposition and subsequent mobilization. PMID:17894785

Neuberger, Thomas; Sreenivasulu, Nese; Rokitta, Markus; Rolletschek, Hardy; Göbel, Cornelia; Rutten, Twan; Radchuk, Volodja; Feussner, Ivo; Wobus, Ulrich; Jakob, Peter; Webb, Andrew; Borisjuk, Ljudmilla

2008-01-01

225

CW injection seeding of a modelocked semiconductor laser  

SciTech Connect

This paper reports on the injection locking technique to control the output of a modelocked semiconductor laser with an external CW signal. With this injection seeding technique, the authors have obtained over 8 mW of average power in 30 ps pulses with side cluster suppression of over 20 dB from an actively modelocked AlGaAs semiconductor laser. This average output power compares favorably with the 12 mW CW output power of the extended resonator. The frequency spectrum of the laser is determined by the background noise level as set by the spontaneous emission. Injection seeding overrides the noise and concentrates over 99% of the available energy in a single nearly transform-limited pulse.

Joneckis, L.G.; Ho, P.T.; Burdge, G.L. (Lab. for Physical Sciences, College Park, MD (US))

1991-07-01

226

Getting of the seeds-and-tools treadmill with CRS seed vouchers and fairs.  

PubMed

The free distribution of seeds and tools is the standard approach to agricultural recovery. The predominance of this approach is partly attributable to the: (1) perception that farmer seed quality is poor, (2) insistence on seed certification, (3) promotion of researcher varieties, (4) misdiagnosis of unavailability, (5) difficulty accessing farmer seed, and (6) support for the commercial seed sector. This paper presents a Seed Security Assessment Framework to distinguish among the causes of seed insecurity and focuses on three principal concepts: seed availability; access to seed; and factors associated with seed utilisation. Using this diagnostic framework, Catholic Relief Services (CRS) has developed a better approach to promoting seed system-based agricultural recovery. It involves a combination of seed voucher distribution and the organization of seed fairs, which bring together a range of sellers from whom the holders of vouchers may purchase seed. This approach is advantageous because it: strengthens farmer seed procurement systems; is cost efficient; in economic terms, has a multiplier effect in the community; is straightforward to plan and implement; allows commercial sector participation; provides an opportunity to promote improved varieties for farmer evaluation; brings together different communities. PMID:12518508

Remington, Tom; Maroko, Jeremiah; Walsh, Stephen; Omanga, Paul; Charles, Edward

2002-12-01

227

Self-seeding ring optical parametric oscillator  

DOEpatents

An optical parametric oscillator apparatus utilizing self-seeding with an external nanosecond-duration pump source to generate a seed pulse resulting in increased conversion efficiency. An optical parametric oscillator with a ring configuration are combined with a pump that injection seeds the optical parametric oscillator with a nanosecond duration, mJ pulse in the reverse direction as the main pulse. A retroreflecting means outside the cavity injects the seed pulse back into the cavity in the direction of the main pulse to seed the main pulse, resulting in higher conversion efficiency.

Smith, Arlee V. (Albuquerque, NM); Armstrong, Darrell J. (Albuquerque, NM)

2005-12-27

228

Methods of estimating seed banks with reference to long-term seed burial.  

PubMed

We compared two standard seed-bank estimation techniques using buried seed populations that had been covered to depths of >1 m by volcanic deposits for 20 years. Some seeds were germinated in a greenhouse (germination method [GM]), and other seeds were extracted by flotation using 50% K(2)CO(3) solution (flotation method [FM]). In total, FM could detect more species and seeds in the soils than GM. However, many species that were extracted by FM did not germinate by GM and smaller seeds were extracted to a lesser extent by FM. FM and GM have distinct advantages and disadvantages. We concluded that the application of a single method should be avoided in estimating seed banks, in particular for long-lived seed banks, because the seeds cannot be readily germinated and are structurally weak. PMID:15034763

Ishikawa-Goto, Masaki; Tsuyuzaki, Shiro

2004-06-01

229

The role of local species pool, soil seed bank and seedling pool in natural vegetation restoration on abandoned slope land  

NASA Astrophysics Data System (ADS)

Theory and empirical evidence suggest that natural vegetation restoration depends on both the availability of seed resources and on successful seedling establishment. In the hill-gully Loess Plateau region, it remains unclear whether a rich diversity of species persists in the fragmented landscape in spite of intensive human activities and whether the distribution of the soil seed bank and the establishment of seedlings are threatened by serious soil erosion. We investigated vegetation composition in a series of plots with different slope aspects and degrees in a watershed of 8.26 km2 in Shaanxi Provence, China to determine the local species pool. The soil seed bank and seedling recruitment on typical eroded slopes over varied erosion zones were simultaneously studied to characterise soil seed bank resources and seedling establishment. In this study, 133 species were identified in the local species pool. The species' frequency within the soil seed bank, seedling and standing vegetation was positively correlated with the frequency of matched species in the local species pool. The soil seed bank density and species richness had no significantly decreasing with the soil erosion intensity increasing on the hill slope. However, the seedling density and species composition showed significant difference among the investigative times and different erosion zones. Furthermore, the species frequency declined with increasing seed mass. Results of this study indicate that the seeds of widely distributed species always have small size, persist in soil under eroded conditions and have stable seedling density over the growing season. Therefore, these species can successfully recolonise in abandoned slope land. However, late-successional species with large seeds that lack dispersal vectors are less able to disperse and recolonise in areas that need to be restored.

Wang, Ning; Jiao, Juying; Du, Huadong; Wang, Dongli; Jia, Yanfeng; Chen, Yu

2013-04-01

230

Stimulated Raman scattering and four-wave Raman mixing seeded by a supercontinuum generated in dibromomethane using picosecond and femtosecond laser sources  

Microsoft Academic Search

Stimulated Raman emission from liquid dibromomethane (vibrational Raman shift frequency, 588 cm?1) is introduced into hydrogen gas (rotational Raman shift frequency, 587 cm?1) as a seed beam, in order to generate numerous rotational lines by four-wave Raman mixing. Unexpectedly, a supercontinuum, which is generated by self-phase modulation in dibromomethane, acted as a seed beam to exclusively generate vibrational lines; the

Hiroyuki Kawano; Tomonori Mori; Yasuyuki Hirakawa; Totaro Imasaka

1999-01-01

231

Pulse compression of CW injection seeded gain-switched diode laser  

Microsoft Academic Search

A commercially available gain-switched diode laser was injection seeded by a CW laser diode to provide a controlled frequency chirped output which was compressed by a grating pair and telescope. Pulses were generated with a width of 12 ps and a peak power of 0.19 W at a repetition rate of 3.2 GHz

Gary M. Carter; Liu Zheng

1992-01-01

232

Electrically wavelength-tunable pulses generated by synchronous two-way injection seeding  

Microsoft Academic Search

We propose and experimentally demonstrate a scheme for the generation of wavelength-tunable pulses from two mutually injection seeded Fabry-Perot laser diodes. The wavelength tuning is achieved by electrical control of the delay time between two RF signals driving the lasers. A linear tuning characteristic is obtained at a constant operating frequency of 1 GHz. The output has a sidemode suppression

K. Chan; C. Shu

1999-01-01

233

Fast wavelength-tunable multichannel switching using a self-injection seeding scheme  

Microsoft Academic Search

Wavelength-tunable switching among different channels in the range of hundreds of megahertz has been demonstrated by the self-injection seeding mechanism. The different wavelength components have been switched by sequentially feeding back the temporally separated cavity modes to the laser diode. The spacing between different wavelengths has been tuned by adjusting the electrical modulation frequency and the length of the dispersive

Sui-Pan Yam; Chester Shu

1999-01-01

234

Conventional and in situ transesterification of sunflower seed oil for the production of biodiesel  

Microsoft Academic Search

In the present work the alkaline transesterification of sunflower seed oil with methanol and ethanol, for the production of biodiesel fuel was studied. Both conventional and in situ transesterification were investigated using low frequency ultrasonication (24 kHz) and mechanical stirring (600 rpm). Use of ultrasonication in conventional transesterification with methanol gave high yields of methyl esters (95%) after a short reaction time

K. G. Georgogianni; M. G. Kontominas; P. J. Pomonis; D. Avlonitis; V. Gergis

2008-01-01

235

Measurement of grain and seed microwave permittivity for moisture and density determination  

Microsoft Academic Search

The importance of moisture measurement in grain and seed is discussed, and a brief history of the development of moisture sensing instruments, based on sensing of dielectric properties of these materials, is presented. Data are presented graphically on the permittivities or dielectric properties of wheat, showing their variation with frequency and moisture content, and references are cited for further information.

Stuart O. Nelson; Samir Trabelsi

2010-01-01

236

Determination of dielectric properties of corn seeds from 1 to 100 MHz  

Microsoft Academic Search

The dielectric properties of corn seeds were determined in the ranges of 9.71–21.51% wet basis (w.b.) for moisture content, 772.5–902.2kg\\/m3 for bulk density and 1–100MHz for frequency of applied electric field using a coaxial capacitor sample holder. Effects of the parameters such as moisture content, bulk density and frequency on the dielectric properties were investigated. The dielectric constant, loss factor

Kamil Sacilik; Ahmet Colak

2010-01-01

237

Water binding in legume seeds  

NASA Technical Reports Server (NTRS)

The physical status of water in seeds has a pivotal role in determining the physiological reactions that can take place in the dry state. Using water sorption isotherms from cotyledon and axis tissue of five leguminous seeds, the strength of water binding and the numbers of binding sites have been estimated using van't Hoff analyses and the D'Arcy/Watt equation. These parameters of water sorption are calculated for each of the three regions of water binding and for a range of temperatures. Water sorption characteristics are reflective of the chemical composition of the biological materials as well as the temperature at which hydration takes place. Changes in the sorption characteristics with temperature and hydration level may suggest hydration-induced structural changes in cellular components.

Vertucci, C. W.; Leopold, A. C.

1987-01-01

238

Comparative study of spectral narrowing of a pulsed Ti:Sapphire laser using pulsed and CW injection seeding  

Microsoft Academic Search

We report a comparative study of a pulsed as well as continuous-wave (cw) injection seeding of a Ti:Sapphire laser pumped by aQ-switched frequency-doubled Nd3+:YAG laser for achieving narrow spectral bandwidth. The results have indicated that the Ti:Sapphire laser using either a pulsed or a cw injection seeding could achieve efficient energy extraction in a narrow spectral bandwidth. In the case

N. J. Vasa; M. Tanaka; T. Okada; M. Maeda; O. Uchino

1996-01-01

239

Compounds That Promote Seed Germination  

NSDL National Science Digital Library

The two molecules for this month come from the section Compound in Smoke Provides the Spark for Germination in the article about "Research Advances" by Angela G. King. These molecules have been demonstrated to stimulate seed germination under various conditions. The butenolide moiety is frequently encountered in natural products. An interesting approach to the synthesis of such molecules can be found in this Organic Letters article (accessed January 2005).

240

Elastohydrodynamic properties of seed oils  

Microsoft Academic Search

The film-forming properties of canola (CAN), soybean (SBO), and jojoba (JO) seed oils under elastohydrodynamic (EHD) conditions\\u000a were investigated to determine whether differences in their chemical and physical properties affect their EHD properties.\\u000a Polyalphaolefin (PAO), whose EHD properties have been reported before, was used as the reference synthetic oil. The effect\\u000a of measurement variables (speed, load, and temperature) on the

G. Biresaw

2006-01-01

241

Generation of Particles and Seeding  

NASA Technical Reports Server (NTRS)

One of the most important elements in laser velocimetry, yet the most neglected, is the small particle embedded in the flow field that scatters the light necessary to make velocity measurements. An attempt to remove the confusion in choosing a seeding method by assessing many of the techniques currently used is presented. Their characteristics and typical limitations imposed by various applications are outlined. The ramifications of these methods on measurement accuracy are addressed.

Meyers, James F.

1991-01-01

242

Optimal seedings in elimination tournaments  

Microsoft Academic Search

We study an elimination tournament with heterogenous contestants whose ability is common-knowledge. Each pair-wise match is\\u000a modeled as an all-pay auction. Equilibrium efforts are in mixed strategies, yielding complex dynamics: endogenous win probabilities\\u000a in each match depend on other matches’ outcome through the identity of the expected opponent in the next round. The designer\\u000a seeds competitors according to their ranks.

Christian Groh; Benny Moldovanu; Aner Sela; Uwe Sunde

2012-01-01

243

Vertical Bridgman growth of sapphire-Seed crystal shapes and seeding characteristics  

NASA Astrophysics Data System (ADS)

The growth of sapphire by the traditional vertical Bridgman (VB) method was studied by using various shapes of seed crystals and tungsten (W) crucibles shaped to match the seeds. Approximately 2-in. diameter, c-axis sapphire single crystals were reproducibly grown from three kinds of seed: thin, tapered and full diameter. Factors relating seed type to single-crystal growth are discussed, including the reproducibility of seeding processes, and the generation and elimination of low-angle grain boundaries (LAGBs). What was learned facilitated the subsequent growth of large-diameter, 3-, 4- and 6-in., c-axis single-crystal sapphires from full-diameter seeds.

Hoshikawa, K.; Osada, J.; Saitou, Y.; Ohba, E.; Miyagawa, C.; Kobayashi, T.; Yanagisawa, J.; Shinozuka, M.; Kanno, K.

2014-06-01

244

Frequency domain optical parametric amplification  

PubMed Central

Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43?mJ two-cycle pulses at 1.8??m wavelength.

Schmidt, Bruno E.; Thire, Nicolas; Boivin, Maxime; Laramee, Antoine; Poitras, Francois; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Legare, Francois

2014-01-01

245

Frequency domain optical parametric amplification.  

PubMed

Today's ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43?mJ two-cycle pulses at 1.8??m wavelength. PMID:24805968

Schmidt, Bruno E; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

2014-01-01

246

Frequency domain optical parametric amplification  

NASA Astrophysics Data System (ADS)

Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43?mJ two-cycle pulses at 1.8??m wavelength.

Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

2014-05-01

247

Proteomics of rice seed germination  

PubMed Central

Seed is a condensed form of plant. Under suitable environmental conditions, it can resume the metabolic activity from physiological quiescent status, and mobilize the reserves, biosynthesize new proteins, regenerate organelles, and cell membrane, eventually protrude the radicle and enter into seedling establishment. So far, how these activities are regulated in a coordinated and sequential manner is largely unknown. With the availability of more and more genome sequence information and the development of mass spectrometry (MS) technology, proteomics has been widely applied in analyzing the mechanisms of different biological processes, and proved to be very powerful. Regulation of rice seed germination is critical for rice cultivation. In recent years, a lot of proteomic studies have been conducted in exploring the gene expression regulation, reserves mobilization and metabolisms reactivation, which brings us new insights on the mechanisms of metabolism regulation during this process. Nevertheless, it also invokes a lot of questions. In this mini-review, we summarized the progress in the proteomic studies of rice seed germination. The current challenges and future perspectives were also discussed, which might be helpful for the following studies.

He, Dongli; Yang, Pingfang

2013-01-01

248

Local evolution of seed flotation in Arabidopsis.  

PubMed

Arabidopsis seeds rapidly release hydrophilic polysaccharides from the seed coat on imbibition. These form a heavy mucilage layer around the seed that makes it sink in water. Fourteen natural Arabidopsis variants from central Asia and Scandinavia were identified with seeds that have modified mucilage release and float. Four of these have a novel mucilage phenotype with almost none of the released mucilage adhering to the seed and the absence of cellulose microfibrils. Mucilage release was modified in the variants by ten independent causal mutations in four different loci. Seven distinct mutations affected one locus, coding the MUM2 ?-D-galactosidase, and represent a striking example of allelic heterogeneity. The modification of mucilage release has thus evolved a number of times independently in two restricted geographical zones. All the natural mutants identified still accumulated mucilage polysaccharides in seed coat epidermal cells. Using nuclear magnetic resonance (NMR) relaxometry their production and retention was shown to reduce water mobility into internal seed tissues during imbibition, which would help to maintain seed buoyancy. Surprisingly, despite released mucilage being an excellent hydrogel it did not increase the rate of water uptake by internal seed tissues and is more likely to play a role in retaining water around the seed. PMID:24625826

Saez-Aguayo, Susana; Rondeau-Mouro, Corinne; Macquet, Audrey; Kronholm, Ilkka; Ralet, Marie-Christine; Berger, Adeline; Sallé, Christine; Poulain, Damien; Granier, Fabienne; Botran, Lucy; Loudet, Olivier; de Meaux, Juliette; Marion-Poll, Annie; North, Helen M

2014-03-01

249

The Potential Roles of Seeds and Seed Bioactives on the Prevention and Treatment of Breast and Prostate Cancer  

Microsoft Academic Search

\\u000a Several seeds have been suggested to play a role in the prevention and treatment of cancer. These include flaxseed, grape\\u000a seed, sesame seed, pomegranate seed, caper seed, black cumin seed, and adlay seed. This chapter describes the research to\\u000a date on the determination of their anticancer effects using different experimental models (in vitro, animal, clinical), the\\u000a findings identifying the active

Krista A. Power; Lilian U. Thompson

250

Effects of rodent species, seed species, and predator cues on seed fate  

USGS Publications Warehouse

Seed selection, removal and subsequent management by granivorous animals is thought to be a complex interaction of factors including qualities of the seeds themselves (e.g., seed size, nutritional quality) and features of the local habitat (e.g. perceived predator risk). At the same time, differential seed selection and dispersal is thought to have profound effects on seed fate and potentially vegetation dynamics. In a feeding arena, we tested whether rodent species, seed species, and indirect and direct predation cues influence seed selection and handling behaviors (e.g., scatter hoarding versus larder hoarding) of two heteromyid rodents, Ord's kangaroo rat (Dipodomys ordii) and the Great Basin pocket mouse (Perognathus parvus). The indirect cue was shrub cover, a feature of the environment. Direct cues, presented individually, were (1) control, (2) coyote (Canis latrans) vocalization, (3) coyote scent, (4) red fox (Vulpes vulpes) scent, or (5) short-eared owl (Asio flammeus) vocalization. We offered seeds of three sizes: two native grasses, Indian ricegrass (Achnatherum hymenoides) and bluebunch wheatgrass (Pseudoroegneria spicata), and the non-native cereal rye (Secale cereale), each in separate trays. Kangaroo rats preferentially harvested Indian ricegrass while pocket mice predominately harvested Indian ricegrass and cereal rye. Pocket mice were more likely to scatter hoard preferred seeds, whereas kangaroo rats mostly consumed and/or larder hoarded preferred seeds. No predator cue significantly affected seed preferences. However, both species altered seed handling behavior in response to direct predation cues by leaving more seeds available in the seed pool, though they responded to different predator cues. If these results translate to natural dynamics on the landscape, the two rodents are expected to have different impacts on seed survival and plant recruitment via their different seed selection and seed handling behaviors.

Sivy, Kelly J.; Ostoja, Steven M.; Schupp, Eugene W.; Durham, Susan

2011-01-01

251

Elemental Concentrations in the Seed of Mutants and Natural Variants of Arabidopsis thaliana Grown under Varying Soil Conditions  

PubMed Central

The concentrations of mineral nutrients in seeds are critical to both the life cycle of plants as well as human nutrition. These concentrations are strongly influenced by soil conditions, as shown here by quantifying the concentration of 14 elements in seeds from Arabidopsis thaliana plants grown under four different soil conditions: standard, or modified with NaCl, heavy metals, or alkali. Each of the modified soils resulted in a unique change to the seed ionome (the mineral nutrient content of the seeds). To help identify the genetic networks regulating the seed ionome, changes in elemental concentrations were evaluated using mutants corresponding to 760 genes as well as 10 naturally occurring accessions. The frequency of ionomic phenotypes supports an estimate that as much as 11% of the A. thaliana genome encodes proteins of functional relevance to ion homeostasis in seeds. A subset of mutants were analyzed with two independent alleles, providing five examples of genes important for regulation of the seed ionome: SOS2, ABH1, CCC, At3g14280 and CNGC2. In a comparison of nine different accessions to a Col-0 reference, eight accessions were observed to have reproducible differences in elemental concentrations, seven of which were dependent on specific soil conditions. These results indicate that the A. thaliana seed ionome is distinct from the vegetative ionome, and that elemental analysis is a sensitive approach to identify genes controlling ion homeostasis, including those that regulate gene expression, phospho-regulation, and ion transport.

McDowell, Stephen C.; Akmakjian, Garo; Sladek, Chris; Mendoza-Cozatl, David; Morrissey, Joe B.; Saini, Nick; Mittler, Ron; Baxter, Ivan; Salt, David E.; Ward, John M.; Schroeder, Julian I.; Guerinot, Mary Lou; Harper, Jeffrey F.

2013-01-01

252

Tannin concentration enhances seed caching by scatter-hoarding rodents: An experiment using artificial ‘seeds  

NASA Astrophysics Data System (ADS)

Tannins are very common among plant seeds but their effects on the fate of seeds, for example, via mediation of the feeding preferences of scatter-hoarding rodents, are poorly understood. In this study, we created a series of artificial 'seeds' that only differed in tannin concentration and the type of tannin, and placed them in a pine forest in the Shangri-La Alpine Botanical Garden, Yunnan Province of China. Two rodent species ( Apodemus latronum and A. chevrieri) showed significant preferences for 'seeds' with different tannin concentrations. A significantly higher proportion of seeds with low tannin concentration were consumed in situ compared with seeds with a higher tannin concentration. Meanwhile, the tannin concentration was significantly positively correlated with the proportion of seeds cached. The different types of tannin (hydrolysable tannin vs condensed tannin) did not differ significantly in their effect on the proportion of seeds eaten in situ vs seeds cached. Tannin concentrations had no significant effect on the distance that cached seeds were carried, which suggests that rodents may respond to different seed traits in deciding whether or not to cache seeds and how far they will transport seeds.

Wang, Bo; Chen, Jin

2008-11-01

253

Spectrally-resolved statistical characterization of seeded supercontinuum suppression using optical time-stretch.  

PubMed

Real-time experimental measurements of the spectrally-resolved noise properties of supercontinuum (SC) have been challenging because of the lack of ultrafast optical spectrometer technologies. Understanding the SC noise is increasingly important because it not only can gain new insight of the complex spectral dynamics of SC generation, but also provides clues to search for stable SC source. Driven by the intense interest in the active seeding mechanism for SC generation, we experimentally demonstrate real-time spectrally-resolved, broadband, statistical characterization of minute continuous-wave (CW) seeded SC, enabled by an ultrahigh-speed spectral acquisition technique called optical time-stretch (OTS). The shot-to-shot statistical analysis shows that the seeded SC exhibits a general compromise between SC bandwidth and spectral stability. OTS also allows us to experimentally identify the seeding condition for SC suppression, in which the spectral broadening is mainly contributed by the cascaded parametric process that delays Akhmediev Breather breakup process and subsequent soliton self-frequency shift. Additionally, the characteristic spectral signature of the Raman solitons, which are becalmed by the minute CW seed, can be clearly captured in real-time by OTS operated at a spectral acquisition rate as high as 20 MHz. We anticipate the OTS technique could provide further new insights for understanding more complex mechanisms of seeded-SC generation which can be examined experimentally. PMID:24921306

Ren, Zhibo; Xu, Yiqing; Qiu, Yi; Wong, Kenneth K Y; Tsia, Kevin

2014-05-19

254

Fire increases aboveground biomass, seed production and recruitment success of Molinia caerulea in dry heathland  

NASA Astrophysics Data System (ADS)

During the last decades, the perennial tussock grass Molinia caerulea has shown an increased abundance in European heathlands, most likely as a result of increased nitrogen deposition and altered management schemes. Because of its deciduous nature, Molinia produces large amounts of litter each year, which may affect the intensity and frequency of accidental fires in heathlands. These fires may influence plant population dynamics and heathland community organization through their effects on plant vital attributes and competitive interactions. In this study, fire-induced changes in competitive ability and invasiveness of Molinia through changes in biomass production, seed set and seed germination under both natural and laboratory conditions were investigated. We found that fire significantly increased aboveground biomass, seed set and germination of Molinia. Seed set was twice as high in burned compared to unburned heathland. Two years after fire, seedling densities in natural conditions were on average six times higher in burned than in unburned heathland, which resulted in increased abundance of Molinia after burning. The seed germination experiment indicated that seeds harvested from plants in burned heathland showed higher germination rates than those from unburned heathland. Hence, our results clearly demonstrate increased invasive spread of Molinia after large and intense fires. Active management guidelines are required to prevent further encroachment of Molinia and to lower the probability of large fires altering the heathland community in the future.

Brys, Rein; Jacquemyn, Hans; De Blust, Geert

2005-11-01

255

Biological damage induced by ionizing cosmic rays in dry Arabidopsis seeds.  

PubMed

In September 1987 dry seeds containing embryos of the crucifer plant Arabidopsis thaliana (L.) Heynh, were flown in orbit for 13 days on the Kosmos 1887 satellite. The seeds were fixed on CNd detectors and stored in units of Biorack type I/O. One unit was exposed inside, another one outside the satellite. The temperature profile of the flown seeds inside the satellite was simulated on earth in an identical backup control sample (BC). An additional control (SC) was studied with the original seeds sample. By use of the CNd-detector, HZE-tracks were measured with a PC-assisted microscope. The biological damages were investigated by growing the seeds under controlled climatic conditions. The following biological endpoints of the cosmic radiation damage were studied: germination, radicle length, sublethality, morphological aberrations, flower development, tumorization, embryo lethality inside the siliques. The summarized damage (D) and the mutation frequencies of embyronic lethal genes were calculated. The following results were obtained: the damages increase significantly in orbit at all biological endpoints; germination and fiowerings especially, as well as embryo lethality of fruits and lethal mutation frequency, were maximum mostly for HZE-hit seeds. Additionally, an increase of damage was observed for the seeds of the outside-exposed Biorack in comparison to the inside ones, which was probably caused by less radiation shielding and free space vacuum. The significance of the results obtained is discussed with respect to stress and risk and, thus, the quality of the RBE-factors and heavy ionizing radiation all needed for the very definition of radiation protection standards in space. PMID:11537515

Kranz, A R; Bork, U; Bucker, H; Reitz, G

1990-01-01

256

Applicator Training Manual for: Seed Treatment Pest Control.  

ERIC Educational Resources Information Center

This manual gives general information on seed treatment and type of seeds which can be treated. Also discussed are the problems and pests commonly associated with seed diseases and the fungicides and insecticides used for seed treatment. Information is also given on seed treatment equipment such as dust treaters, slurry treaters, and direct…

TeKrony, Dennis M.

257

Seed dynamics during forest succession in Costa Rica  

Microsoft Academic Search

Soil seed banks and current seed inputs each play a role in tropical succession. We compared the abundance and floristic composition of seeds from these two sources at a Costa Rican site by germinating seeds from the soil, measuring seed inputs for 3 yr, and monitoring the earliest colonists in a forest clearing.

K. R. Young; J. J. Ewel; B. J. Brown

1987-01-01

258

Postdispersal Weed Seed Predation Is Affected by Experimental Substrate  

Microsoft Academic Search

A standard method for evaluating weed seed predation is needed to facilitate generalizations across studies. Identification of general trends could allow practical recommendations for enhancing weed seed predation in agricultural systems. The objective of this study was to compare the commonly used sandpaper and soil substrate methods for offering weed seeds when assessing seed predation rates. Invertebrate seed predators and

Rachel E. Shuler; Antonio DiTommaso; John E. Losey; Charles L. Mohler

2008-01-01

259

Inheritance of seed colour in turnip rape ( Brassica campestris L.)  

Microsoft Academic Search

The inheritance of seed colour was investigated in the progenies of crosses between seven yellow seeded forms and a brown seeded one of turnip rape (Brassica campestris L.). Seed colour differences were found to be determined in each case by one or two genes with epistatic effect. Moreover, independent inheritance of hilum colour was observed. Seed colour was predominantly but

A. Schwetka

1982-01-01

260

Seed Potato Systems in Ecuador: A Case Study.  

National Technical Information Service (NTIS)

Seeds and seed systems, provide a vital link between cropping seasons. The research report, one of a series of case studies of seed potato programs, examines the seed potato system in Ecuador. The system is dominated by a farmer-based informal seed system...

C. C. Crissman J. E. Uquillas

1989-01-01

261

Modification of Seed Germination Performance through Cold Plasma Chemistry Technology  

Microsoft Academic Search

growth regulators to seeds (Silcock and Smith, 1982; Taylor and Harman, 1990; Zarnstorff et al., 1994). One This study was conducted to determine if an alternate seed treat- such treatment is seed coating, the direct application of ment approach based on plasma chemistry would offer a more viable material to a seed surface. Seeds can be treated by alternative over

John C. Volin; Ferencz S. Denes; Raymond A. Young; Scott M. T. Park

2000-01-01

262

Some Physical Properties of Gilaburu Seed  

Microsoft Academic Search

In this study, the physical properties of gilaburu (Viburnum opulus L.) seed have been investigated. The average length, width, thickness and geometric mean diameter values in 54% of moisture content of gilaburu seed were between 6.56 and 8.44 mm, 6.24 and 8.57 mm, 1.62 and 2.52 mm, 4.19 and 5.31 mm, respectively. Sphericity, surface area, thousand seed mass and terminal

Nihat SÖNMEZ; H. A. ALIZADEH; Ramazan ÖZTÜRK

263

Selenium increases seed production in Brassica  

Microsoft Academic Search

Selenium (Se) is essential for humans and animals but is not considered to be essential for higher plants. Although researchers\\u000a have found increases in vegetative growth due to fertiliser Se, there has been no definitive evidence to date of increased\\u000a reproductive capacity, in terms of seed production and seed viability. The aim of this study was to evaluate seed production

G. H. Lyons; Y. Genc; K. Soole; J. C. R. Stangoulis; F. Liu; R. D. Graham

2009-01-01

264

Gene expression analysis of flax seed development  

Microsoft Academic Search

Background  Flax, Linum usitatissimum L., is an important crop whose seed oil and stem fiber have multiple industrial applications. Flax seeds are also well-known\\u000a for their nutritional attributes, viz., omega-3 fatty acids in the oil and lignans and mucilage from the seed coat. In spite\\u000a of the importance of this crop, there are few molecular resources that can be utilized toward

Prakash Venglat; Daoquan Xiang; Shuqing Qiu; Sandra L Stone; Chabane Tibiche; Dustin Cram; Michelle Alting-Mees; Jacek Nowak; Sylvie Cloutier; Michael Deyholos; Faouzi Bekkaoui; Andrew Sharpe; Edwin Wang; Gordon Rowland; Gopalan Selvaraj; Raju Datla

2011-01-01

265

Formation of cloud microstructure during hygroscopic seeding  

Microsoft Academic Search

The evolution of cloud microstructure initiated by hygroscopic seeding is studied on the basis of numerical simulation of\\u000a cloud formation in the initial stage of condensation. The influence of both physicochemical properties of atmospheric aerosol\\u000a and atmospheric conditions controlling the cloud type on the microstructure of a developing cloud (without hygroscopic seeding)\\u000a is analyzed. It is shown that cloud seeding

A. S. Drofa

2006-01-01

266

Effects of elevated CO2 and temperature on seed quality.  

PubMed

Successful crop production depends initially on the availability of high-quality seed. By 2050 global climate change will have influenced crop yields, but will these changes affect seed quality? The present review examines the effects of elevated carbon dioxide (CO2) and temperature during seed production on three seed quality components: seed mass, germination and seed vigour. In response to elevated CO2, seed mass has been reported to both increase and decrease in C3 plants, but not change in C4 plants. Increases are greater in legumes than non-legumes, and there is considerable variation among species. Seed mass increases may result in a decrease of seed nitrogen (N) concentration in non-legumes. Increasing temperature may decrease seed mass because of an accelerated growth rate and reduced seed filling duration, but lower seed mass does not necessarily reduce seed germination or vigour. Like seed mass, reported seed germination responses to elevated CO2 have been variable. The reported changes in seed C/N ratio can decrease seed protein content which may eventually lead to reduced viability. Conversely, increased ethylene production may stimulate germination in some species. High-temperature stress before developing seeds reach physiological maturity (PM) can reduce germination by inhibiting the ability of the plant to supply the assimilates necessary to synthesize the storage compounds required for germination. Nothing is known concerning the effects of elevated CO2 on seed vigour. However, seed vigour can be reduced by high-temperature stress both before and after PM. High temperatures induce or increase the physiological deterioration of seeds. Limited evidence suggests that only short periods of high-temperature stress at critical seed development stages are required to reduce seed vigour, but further research is required. The predicted environmental changes will lead to losses of seed quality, particularly for seed vigour and possibly germination. The seed industry will need to consider management changes to minimize the risk of this occurring. PMID:23495259

Hampton, J G; Boelt, B; Rolston, M P; Chastain, T G

2013-04-01

267

Variation of Mucilage in Flax Seed and Its Relationship with Other Seed Characters  

Microsoft Academic Search

A four-location trial in western Canada with 16 North American flax (Linum usitatissimumL.) cultivars was conducted in 2001 and 2002 to investigate the genotypic and environmental influences on mucilage in the flax seed coat. The viscosity of a water extract from intact flax seed was used as quantitative descriptor of the seed-coat mucilage (mucilage indicator value, MIV). Thousand-seed weight (TSW)

Axel Diederichsen; J. Philip Raney; Scott D. Duguid

2006-01-01

268

Chemical characterization of Central American pitaya (Hylocereussp.) seeds and seed oil  

Microsoft Academic Search

Central American red pitaya (Hylocereussp.) seeds were studied for their chemical and nutritional traits with particular reference to the fatty acid (FA) profile of the seed oil. Proximate seed composition averaged 352 g\\/kg, 302 g\\/kg, 296 g\\/kg, 206 g\\/kg, 126 g\\/kg, and 21 g\\/kg for total carbohydrates, dietary fiber, fat, protein, moisture, and ash, respectively. FA composition of pitaya seed

M. G. Villalobos-Gutiérrez; R. M. Schweiggert; R. Carle; P. Esquivel

2012-01-01

269

EFFICACY OF FUNGICIDAL SEED TREATMENT IN CONTROLLING ALTERNARIA SPP. IN RADISH SEED  

Microsoft Academic Search

Islam, S.S., Rahman, M.H., Hasan, M.J., Ashadusjaman, M. and Khatun, M.M. 2007. Efficacy of Fungicidal Seed Treatment in Controlling Alternaria spp. in Radish Seed. Int. J. Sustain. Crop Prod. 2(5): 46-50 The experiments were conducted to find out effective seed treating fungicides to control seedborne Alternaria spp. of the crop. In the experiment, seeds were treated with the six fungicides

S. S. ISLAM; M. H. RAHMAN; M. J. HASAN

270

Conflicting selection from fire and seed predation drives fine-scaled phenotypic variation in a widespread North American conifer.  

PubMed

Recent work has demonstrated that evolutionary processes shape ecological dynamics on relatively short timescales (eco-evolutionary dynamics), but demonstrating these effects at large spatial scales in natural landscapes has proven difficult. We used empirical studies and modeling to investigate how selective pressures from fire and predispersal seed predation affect the evolution of serotiny, an ecologically important trait. Serotiny is a highly heritable key reproductive trait in Rocky Mountain lodgepole pine (Pinus contorta subsp. latifolia), a conifer that dominates millions of hectares in western North America. In these forests, the frequency of serotiny determines postfire seedling density with corresponding community- and ecosystem-level effects. We found that serotinous individuals have a selective advantage at high fire frequencies and low predation pressure; however, very high seed predation shifted the selective advantage to nonserotinous individuals even at high fire frequencies. Simulation modeling suggests that spatial variation in the frequency of serotiny results from heterogeneity in these two selective agents. These results, combined with previous findings showing a negative association between the density of seed predators and the frequency of serotiny at both landscape and continental scales, demonstrate that contemporary patterns in serotiny reflect an evolutionary response to conflicting selection pressures from fire and seed predation. Thus, we show that variation in the frequency of a heritable polygenic trait depends on spatial variation in two dominant selective agents, and, importantly, the effects of the local trait variation propagate with profound consequences to the structure and function of communities and ecosystems across a large landscape. PMID:24979772

Talluto, Matthew V; Benkman, Craig W

2014-07-01

271

Seed coat has no value in protecting cowpea seed against attack by Callosobruchus maculatus (F.)  

Microsoft Academic Search

Experiments were conducted to compare the oviposition preference of the cowpea seed beetle Callosobruchus maculatus (F.) on 22 cowpea varieties, with and without seed coat. The cowpeas included five resistant, four moderately resistant and 13 susceptible varieties. Ten of the varieties had smooth seed coats while 12 were wrinkled. Mean numbers of eggs laid on smooth and wrinkled varieties were

P. A Edde; C. I Amatobi

2003-01-01

272

Variation of seed mass and its effects on germination in Polylepis australis : implications for seed collection  

Microsoft Academic Search

South American Polylepis mountain forests are recognised as being one of the most endangered forest ecosystems in the world. Reforestation measures\\u000a have been strongly recommended but may be hampered due to the very low seed germination reported for several Polylepis species. In order to facilitate reforestation we analysed the influence of seed mass on germination probability for Polylepis australis seeds

Peggy Seltmann; Ilona Leyer; Daniel Renison; Isabell Hensen

2007-01-01

273

Seed and regeneration ecology in dry Afromontane forests of Ethiopia: I. Seed production - population structures  

Microsoft Academic Search

A series of events occur in the process of regeneration, namely flowering, seed production and dispersal, incorporation of seeds into the soil, seed predation or germination, seedling establishment and growth and formation of seedling banks. Forests are subjected to both natural and anthropogenic disturbances, which disrupt the process of plant regeneration. In response to these disturbances, succession is triggered in

DEMEL TEKETAY

2005-01-01

274

Seed size, shape and vertical distribution in the soil: indicators of seed longevity  

Microsoft Academic Search

Summary 1. We investigated the vertical distribution of seeds in the soil, using data from nine studies in five European countries. We discovered significant correlations between seed shape and distribution in the soil. 2. The classification of the longevity of seeds of plant species has been improved by the introduction of a 'longevity index', expressing on a continuous scale the

R. M. BEKKER; J. P. BAKKER; U. GRANDIN; R. KALAMEES; P. MILBERG; P. POSCHLOD; Ken Thompson; J. H. WILLEMS

1998-01-01

275

Intrapopulation variation in Abutilon theophrasti seed mass and its relationship to seed germinability  

Microsoft Academic Search

The relationship between seed mass variation and germinability in ten Abutilon theophrasti Medic. plants from a single agricultural population was examined under controlled environmental conditions. Seeds were collected in the autumn of 1995 and dry-stored in paper bags at 4°C until the start of trials in the spring of 1998. For each plant, between 549 and 1000 randomly selected seeds

Hameed A. Baloch; Antonio DiTommaso; Alan K. Watson

2001-01-01

276

Supplementing seed banks to rehabilitate disturbed Mojave Desert shrublands: where do all the seeds go?  

USGS Publications Warehouse

Revegetation of degraded arid lands often involves supplementing impoverished seed banks and improving the seedbed, yet these approaches frequently fail. To understand these failures, we tracked the fates of seeds for six shrub species that were broadcast across two contrasting surface disturbances common to the Mojave Desert—sites compacted by concentrated vehicle use and trenched sites where topsoil and subsurface soils were mixed. We evaluated seedbed treatments that enhance soil-seed contact (tackifier) and create surface roughness while reducing soil bulk density (harrowing). We also explored whether seed harvesting by granivores and seedling suppression by non-native annuals influence the success of broadcast seeding in revegetating degraded shrublands. Ten weeks after treatments, seeds readily moved off of experimental plots in untreated compacted sites, but seed movements were reduced 32% by tackifier and 55% through harrowing. Harrowing promoted seedling emergence in compacted sites, particularly for the early-colonizing species Encelia farinosa, but tackifier was largely ineffective. The inherent surface roughness of trenched sites retained three times the number of seeds than compacted sites, but soil mixing during trench development likely altered the suitability of the seedbed thus resulting in poor seedling emergence. Non-native annuals had little influence on seed fates during our study. In contrast, the prevalence of harvester ants increased seed removal on compacted sites, whereas rodent activity influenced removal on trenched sites. Future success of broadcast seeding in arid lands depends on evaluating disturbance characteristics prior to seeding and selecting appropriate species and seasons for application.

DeFalco, Lesley A.; Esque, Todd C.; Nicklas, Melissa B.; Kane, Jeffrey M.

2012-01-01

277

``From seed-to-seed'' experiment with wheat plants under space-flight conditions  

Microsoft Academic Search

An important goal with plant experiments in microgravity is to achieve a complete life cycle, the ``seed-to-seed experiment''. Some Soviet attempts to reach this goal are described, notably an experiment with the tiny mustard, Arabidopsis thaliana, in the Phyton 3 device on Salyut 7. Normal seeds were produced although yields were reduced and development was delayed. Several other experiments have

A. Mashinsky; I. Ivanova; T. Derendyaeva; G. Nechitailo; F. Salisbury

1994-01-01

278

Coherence-based photoacoustic imaging of brachytherapy seeds implanted in a canine prostate  

NASA Astrophysics Data System (ADS)

Visualization of individual brachytherapy seed locations assists with intraoperative updates to brachytherapy treatment plans. Photoacoustic imaging is advantageous when compared to current ultrasound imaging methods, due to its superior sensitivity to metal surrounded by tissue. However, photoacoustic images suffer from poor contrast with insufficient laser fluence. A short-lag spatial coherence (SLSC) beamformer was implemented to enhance these low-contrast photoacoustic signals. Photoacoustic imaging was performed with a transrectal ultrasound probe and an optical fiber surrounded by a light-diffusing sheath, placed at a distance of approximately 4-5 mm from the location of seeds implanted in an in vivo canine prostate. The average energy density through the tip of the sheath was varied from 8 to 167 mJ/cm2. When compared to a fast Fourier transform (FFT)- based reconstruction method, the mean contrast and signal-to-noise ratios were improved by up to 22 dB and a factor of 4, respectively, with the SLSC beamformer (12% of the receive aperture elements were included in the short-lag sum). Image artifacts that were spatially coherent had spatial frequency spectra that were quadrantally symmetric about the origin, while the spatial frequency spectra of the seed signals possessed diagonal symmetry. These differences were utilized to reduce artifacts by 9-14 dB after applying a bandpass filter with diagonal symmetry. Results indicate that advanced methods, such as SLSC beamforming or frequency-based filters, hold promise for intraoperative localization of prostate brachytherapy seeds

Lediju Bell, Muyinatu A.; Song, Danny Y.; Boctor, Emad M.

2014-03-01

279

The seeded growth of graphene  

PubMed Central

In this paper, we demonstrate the seeded growth of graphene under a plasma chemical vapor deposition condition. First, we fabricate graphene nanopowders (~5?nm) by ball-milling commercial multi-wall carbon nanotubes. The graphene nanoparticles were subsequently subject to a direct current plasma generated in a 100?Torr 10%CH4 - 90%H2 gas mixture. The plasma growth enlarged, over one hour, the nuclei to graphene sheets larger than one hundred nm2 in area. Characterization by electron and X-ray diffraction, high-resolution transmission electron microscopy images provide evidence for the presence of monolayer graphene sheets.

Lee, Jae-Kap; Lee, Sohyung; Kim, Yong-Il; Kim, Jin-Gyu; Min, Bong-Ki; Lee, Kyung-Il; Park, Yeseul; John, Phillip

2014-01-01

280

The seeded growth of graphene.  

PubMed

In this paper, we demonstrate the seeded growth of graphene under a plasma chemical vapor deposition condition. First, we fabricate graphene nanopowders (~5?nm) by ball-milling commercial multi-wall carbon nanotubes. The graphene nanoparticles were subsequently subject to a direct current plasma generated in a 100?Torr 10%CH4 - 90%H2 gas mixture. The plasma growth enlarged, over one hour, the nuclei to graphene sheets larger than one hundred nm(2) in area. Characterization by electron and X-ray diffraction, high-resolution transmission electron microscopy images provide evidence for the presence of monolayer graphene sheets. PMID:25022816

Lee, Jae-Kap; Lee, Sohyung; Kim, Yong-Il; Kim, Jin-Gyu; Min, Bong-Ki; Lee, Kyung-Il; Park, Yeseul; John, Phillip

2014-01-01

281

Dispersal of mimetic seeds of three species of Ormosia (Leguminosae)  

USGS Publications Warehouse

Seeds with 'imitation arils' appear wholly or partially covered by pulp or aril but actually carry no fleshy material. The mimetic seed hypothesis to explain this phenomenon proposes a parasitic relationship in which birds are deceived into dispersing seeds that resemble bird-dispersed fruits, without receiving a nutrient reward. The hard-seed for grit hypothesis proposes a mutualistic relationship in which large, terrestrial birds swallow the exceptionally hard 'mimetic' seeds as grit for grinding the softer seeds on which they feed. They defecate, dispersing the seeds, and abrade the seed surface, enhancing germination. Any fruit mimicry is incidental. Fruiting trees of Ormosia spp. (Leguminosae: Papilionoideae) were observed to ascertain mechanisms of seed dispersal and the role of seemingly mimetic characteristics of the seeds in that dispersal. Seed predation and seed germination were also examined. Ormosia isthamensis and O. macrocalyx (but not O. bopiensis) deceived arboreally-foraging frugivorous birds into taking their mimetic seeds, although rates of seed dispersal were low. These results are consistent with the mimetic seed hypothesis. On the other hand, the rates of disappearance of seeds from the ground under the Ormosia trees, hardness of the seeds, and enhancement of germination with the abrasion of the seed coat are all consistent with the hard-seed for grit hypothesis.

Foster, M.S.; DeLay, L.S.

1998-01-01

282

Frequency Agility Technique for Frequency Scanned Antenna.  

National Technical Information Service (NTIS)

In a serpentine feed structure for a frequency scanned antenna a switching network is provided which allows the serpentine to be fed from either end on alternate or random scans. This variable transmission system significantly increases the frequency band...

R. R. Boothe

1980-01-01

283

Temporal variation of allele frequencies in a natural population of wild Vigna unguiculata  

Microsoft Academic Search

Temporal variation in allele frequencies in a natural population of wild Vigna unguiculata was studied by making monthly collections of seeds over a two-year period. Using starch gel electrophoresis, four out of seven loci analysed were shown to be polymorphic (Enp, Fdh, Fle3 and Pgd2). These four loci showed significant variation in allele frequencies over time. Changes in population structure

E. B. Kouam; R. S. Pasquet; G. M. Muluvi

2012-01-01

284

Low-Cost, Single-Frequency Sources for Spectroscopy using Conventional Fabry-Perot Diode Lasers  

NASA Technical Reports Server (NTRS)

Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

Duerksen, Gary L.; Krainak, Michael A.

1999-01-01

285

Low-Cost, Single-Frequency Sources for Spectroscopy Using Conventional Fabry-Perot Diode Lasers  

NASA Technical Reports Server (NTRS)

Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

Krainak, Michael A.; Duerksen, Gary L.

1999-01-01

286

Seed Anatomy and Water Uptake in Relation to Seed Dormancy in Opuntia tomentosa (Cactaceae, Opuntioideae)  

PubMed Central

Background and Aims There is considerable confusion in the literature concerning impermeability of seeds with ‘hard’ seed coats, because the ability to take up (imbibe) water has not been tested in most of them. Seeds of Opuntia tomentosa were reported recently to have a water-impermeable seed coat sensu lato (i.e. physical dormancy), in combination with physiological dormancy. However, physical dormancy is not known to occur in Cactaceae. Therefore, the aim of this study was to determine if seeds of O. tomentosa are water-permeable or water-impermeable, i.e. if they have physical dormancy. Methods The micromorphology of the seed coat and associated structures were characterized by SEM and light microscopy. Permeability of the seed-covering layers was assessed by an increase in mass of seeds on a wet substrate and by dye-tracking and uptake of tritiated water by intact versus scarified seeds. Key Results A germination valve and a water channel are formed in the hilum–micropyle region during dehydration and ageing in seeds of O. tomentosa. The funicular envelope undoubtedly plays a role in germination of Opuntia seeds via restriction of water uptake and mechanical resistance to expansion of the embryo. However, seeds do not exhibit any of three features characteristic of those with physical dormancy. Thus, they do not have a water-impermeable layer(s) of palisade cells (macrosclereids) or a water gap sensu stricto and they imbibe water without the seed coat being disrupted. Conclusions Although dormancy in seeds of this species can be broken by scarification, they have physiological dormancy only. Further, based on information in the literature, it is concluded that it is unlikely that any species of Opuntia has physical dormancy. This is the first integrative study of the anatomy, dynamics of water uptake and dormancy in seeds of Cactaceae subfamily Opuntioideae.

Orozco-Segovia, A.; Marquez-Guzman, J.; Sanchez-Coronado, M. E.; Gamboa de Buen, A.; Baskin, J. M.; Baskin, C. C.

2007-01-01

287

7 CFR 1427.165 - Eligible seed cotton.  

Code of Federal Regulations, 2010 CFR

...cotton. (a) Seed cotton pledged...producer to pledge the seed cotton to CCC as...redeemed; (6) Be production from acreage that...and (b) The quality of cotton which...cotton in each lot of seed cotton as...

2010-01-01

288

7 CFR 1427.165 - Eligible seed cotton.  

Code of Federal Regulations, 2010 CFR

...cotton. (a) Seed cotton pledged...producer to pledge the seed cotton to CCC as...redeemed; (6) Be production from acreage that...and (b) The quality of cotton which...cotton in each lot of seed cotton as...

2009-01-01

289

Optimum Size for Planting Hatchery Produced Oyster Seed.  

National Technical Information Service (NTIS)

The ability of hatcheries to produce oyster seed for stocking a variety of oyster culture operations is well established. Hatchery produced seed has not gained acceptance along the Gulf Coast primarily because survival of seed is poorly understood, partic...

R. K. Wallace F. S. Rikard J. C. Howe D. B. Rouse

2001-01-01

290

7 CFR 201.58a - Indistinguishable seeds.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Indistinguishable seeds. 201.58a Section 201.58a Agriculture ...DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Examinations in the...

2009-01-01

291

7 CFR 201.58a - Indistinguishable seeds.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Indistinguishable seeds. 201.58a Section 201.58a Agriculture ...DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Examinations in the...

2010-01-01

292

7 CFR 945.7 - Certified seed potatoes.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Certified seed potatoes. 945.7 Section 945.7 Agriculture...DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN CERTAIN DESIGNATED COUNTIES...Definitions § 945.7 Certified seed potatoes. Certified seed potatoes means...

2009-01-01

293

Diatom response to extremely low-frequency magnetic fields  

SciTech Connect

Reports that extremely low-frequency magnetic fields can interfere with normal biological cell function continue to stimulate experimental activity as well as investigations into the possible mechanism of the interaction. The cyclotron resonance' model of Liboff has been tested by Smith et al. using as the biological test system the diatom Amphora coffeiformis. They report enhanced motility of the diatom in response to a low-frequency electromagnetic field tuned to the cyclotron resonance condition for calcium ions. We report here an attempt to reproduce their results. Following their protocol diatoms were seeded onto agar plates containing varying amounts of calcium and exposed to colinear DC and AC magnetic fields tuned to the cyclotron resonant condition for frequencies of 16, 30, and 60 Hz. The fractional motility was compared with that of control plates seeded at the same time from the same culture. We find no evidence of a cyclotron resonance effect.

Parkinson, W.C.; Sulik, G.L. (Department of Physics, University of Michigan, Ann Arbor (United States))

1992-06-01

294

Incorporating animal behavior into seed dispersal models: implications for seed shadows.  

PubMed

Seed dispersal fundamentally influences plant population and community dynamics but is difficult to quantify directly. Consequently, models are frequently used to describe the seed shadow (the seed deposition pattern of a plant population). For vertebrate-dispersed plants, animal behavior is known to influence seed shadows but is poorly integrated in seed dispersal models. Here, we illustrate a modeling approach that incorporates animal behavior and develop a stochastic, spatially explicit simulation model that predicts the seed shadow for a primate-dispersed tree species (Virola calophylla, Myristicaceae) at the forest stand scale. The model was parameterized from field-collected data on fruit production and seed dispersal, behaviors and movement patterns of the key disperser, the spider monkey (Ateles paniscus), densities of dispersed and non-dispersed seeds, and direct estimates of seed dispersal distances. Our model demonstrated that the spatial scale of dispersal for this V. calophylla population was large, as spider monkeys routinely dispersed seeds >100 m, a commonly used threshold for long-distance dispersal. The simulated seed shadow was heterogeneous, with high spatial variance in seed density resulting largely from behaviors and movement patterns of spider monkeys that aggregated seeds (dispersal at their sleeping sites) and that scattered seeds (dispersal during diurnal foraging and resting). The single-distribution dispersal kernels frequently used to model dispersal substantially underestimated this variance and poorly fit the simulated seed-dispersal curve, primarily because of its multimodality, and a mixture distribution always fit the simulated dispersal curve better. Both seed shadow heterogeneity and dispersal curve multimodality arose directly from these different dispersal processes generated by spider monkeys. Compared to models that did not account for disperser behavior, our modeling approach improved prediction of the seed shadow of this V. calophylla population. An important function of seed dispersal models is to use the seed shadows they predict to estimate components of plant demography, particularly seedling population dynamics and distributions. Our model demonstrated that improved seed shadow prediction for animal-dispersed plants can be accomplished by incorporating spatially explicit information on disperser behavior and movements, using scales large enough to capture routine long-distance dispersal, and using dispersal kernels, such as mixture distributions, that account for spatially aggregated dispersal. PMID:17249240

Russo, Sabrina E; Portnoy, Stephen; Augspurger, Carol K

2006-12-01

295

Castor Seed Poisoning in Humans: A Review.  

National Technical Information Service (NTIS)

This work reviews 314 cases of poisoning, including 15 deaths which occurred in humans as a result of castor seed ingestion between 1738 and 1988. Castor seed toxicity is due to ricin, a powerful phytotoxin present in the plant and concentrated in the see...

G. J. Klain J. J. Jaeger

1990-01-01

296

Abscisic Acid Levels and Seed Dormancy  

PubMed Central

Dormant seeds from Fraxinus species require cold-temperature after-ripening prior to germination. Earlier, we found that abscisic acid (ABA) will inhibit germination of excised nondormant embryos and that this can be reversed with a combination of gibberellic acid and kinetin. Using Milborrow's quantitative “racemate dilution” method the ABA concentration in 3 types of Fraxinus seed and pericarp were determined. While ABA was present in all tissues, the highest concentration was found in the seed and pericarp of dormant F. americana. During the chilling treatment of F. americana the ABA levels decreased 37% in the pericarp and 68% in the seed. The ABA concentration of the seed of the nondormant species, F. ornus, is as low as that found in F. americana seeds after cold treatment. Experiments with exogenously added ABA solutions indicate that it is unlikely that the ABA in the pericarp functions in the regulation of seed dormancy. However, the ABA in the seed does seem to have a regulatory role in germination. Images

Sondheimer, E.; Tzou, D. S.; Galson, Eva C.

1968-01-01

297

Bronchial asthma due to Cannabis sativa seed.  

PubMed

A 51-year-old man with asthmatic attacks due to Cannabis sativa seed inhalation was studied. Specific IgE against this seed was demonstrated by in vivo (skin and bronchial challenge tests) and in vitro methods (reverse enzyme immunoassay and histamine release from basophils), suggesting a Type I immunologic reaction. PMID:1789408

Vidal, C; Fuente, R; Iglesias, A; Sáez, A

1991-11-01

298

Establishment of Bermudagrass Seeded with Annual Ryegrass.  

National Technical Information Service (NTIS)

Seedling of perennial grasses often are subjected to intense competition and fail to establish a stand. This competition may come from weeds present in the seeded area or from other components of the seed mixture. Competition between plants on the same si...

W. J. Bowmer W. G. McCully

1968-01-01

299

MHD heat and seed recovery technology project  

SciTech Connect

The MHD Heat and Seed Recovery Technology Project at Argonne National Laboratory is obtaining information for the design and operation of the steam plant downstream of the MHD channel-diffuser, and of the seed regeneration process. The project goal is to supply the engineering data required in the design of components for prototype and demonstration MHD facilities. The work is being done in close cooperation with the Heat Recovery-Seed Recovery facility, which will be a 20-MW pilot plant of the MHD steam bottoming system. The primary effort of the HSR Technology Project is directed toward experimental investigations of critical issues, such as 1) NO/sub x/ behavior in the radiant boiler and secondary combustor; 2) radiant boiler design to meet the multiple requirements of steam generation, NO/sub x/ decomposition, and seed slag separation; 3) effects of solid or liquid seed deposits on heat transfer and gas flow in the steam and air heaters; 4) formation, growth, and deposition of seed-slag particles, 5) character of the combustion gas effluents, and 6) the corrosion and erosion of ceramic and metallic materials of construction. These investigations are performed primarily in a 2-MW test facility, Argonne MHD Process Engineering Laboratory (AMPEL). Other project activities are related to studies of the thermochemistry of the seed-slag combustion gas system, identification of ceramic and metallic materials for service in the MHD-steam plant, and evaluation of seed regeneration processes. Progress is reported.

Petrick, M.; Johnson, T.R.

1980-08-01

300

Photomanipulation of Phytochrome in Lettuce Seeds  

PubMed Central

Seeds of lettuce (Lactuca sativa L. cv. Grand Rapids) were imbibed and given either short irradiation with red or far red light prior to drying or dried under continuous red or far red light. Seeds treated with either short or continuous red germinate in darkness, whereas seeds treated with either short or continuous far red require a short exposure to red light, after a period of imbibition, to stimulate germination. Irradiation of dry red seeds with far red light immediately before sowing results in a marked inhibition of germination. This result was predicted since far red-absorbing form phytochrome can be photoconverted to the intermediate P650 (absorbance maximum 650 nm) in freeze-dried tissue. A similar far red treatment to continuous red seeds is less effective and it is concluded that in these seeds a proportion of total phytochrome is blocked as intermediates between red-absorbing and far red-absorbing form phytochrome, which only form the far red-absorbing form of phytochrome on imbibition. The inhibition of dry short red seeds by far red light can be reversed by an irradiation with short red light given immediately before sowing, confirming that P650 can be photoconverted back to the far red-absorbing form of phytochrome. The results are discussed in relation to seed maturation (dehydration) on the parent plant.

Kendrick, Richard E.; Russell, Jane H.

1975-01-01

301

Policosanol content and composition in perilla seeds.  

PubMed

Policosanols, long-chain alcohols, have many beneficial physiological activities. Contents and compositions in perilla seeds (Perilla frutescens) produced in Korea and China were determined. Waxy materials were extracted from perilla seeds using hot hexane. Yield of the waxy materials from perilla seeds was 72.1 mg/100 g of dry weight. Contents and compositions of the waxy materials and policosanols were identified and quantified by TLC, HPLC, and GC. Major components of the waxy materials from Korean and Chinese perilla seeds were policosanols (25.5 and 34.8%, respectively), hydrocarbons (18.8 and 10.5%), wax esters, steryl esters and aldehydes (53.0 and 49.8%), acids (1.7 and 2.1%), and triacylglycerols (1.0 and 2.9%), determined by HPLC. For comparison, waxy materials of sesame seeds were also analyzed. Yield of the waxy materials from sesame seeds were 8.6 mg/100 g. Less than 5% policosanols were detected in the waxy materials extracted from sesame seeds produced in Korea and China. Wax esters or steryl esters accounted for 93-95% of the sesame waxy materials. Policosanols in the perilla seeds were composed of 67-68% octacosanol, 16-17% hexacosanol, 6-9% triacontanol, and others. PMID:16848517

Adhikari, Prakash; Hwang, Keum Taek; Park, Jae Nam; Kim, Choong Ki

2006-07-26

302

9 CFR 101.7 - Seed organisms.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Seed organisms. 101.7 Section 101.7 Animals...SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS DEFINITIONS § 101.7 Seed organisms. When used in conjunction with or...

2010-01-01

303

9 CFR 101.7 - Seed organisms.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Seed organisms. 101.7 Section 101.7 Animals...SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS DEFINITIONS § 101.7 Seed organisms. When used in conjunction with or...

2009-01-01

304

Grass Seed Structure and Seedling Emergence  

NSDL National Science Digital Library

This activity discusses both seed structure and seedling emergence in monocots. Through active learning elements, photos and text students will discover the basic anatomy of seeds and the function of each structure. The process of seedling emergence is presented in detail including the difference between emergence in cool-season and warm-season grasses.

305

Usual Intake of Nuts and seeds  

Cancer.gov

Usual Intake of Nuts and seeds Table A31. Nuts and seeds: Means, percentiles and standard errors of usual intake, 2007-2010 Age (Years) N1 oz equivalents3 Mean (SE)2 5% (SE) 10% (SE) 25% (SE) 50% (SE) 75% (SE) 90% (SE) 95% (SE) Males 1-3 774 0.3 (0.04) 0.0

306

Calculations Pertaining to Hygroscopic Seeding with Flares  

Microsoft Academic Search

Some possible effects of hygroscopic seeding with flares are explored by calculating how such seeding would modify the initial size distribution of cloud droplets and the subsequent evolution of that size distribution by coalescence. To be representative of recent experiments in South Africa, the calculations emphasize the effects of hygroscopic particles that can be produced by flares, instead of the

William A. Cooper; Roelof T. Bruintjes; Graeme K. Mather

1997-01-01

307

Membrane organization in soybean seeds during hydration  

Microsoft Academic Search

The ability of seeds to withstand dehydration indicates that their membranes may maintain structural integrity even when dry. Analysis of polar lipids (the principal lipidic constituents of the membranes) from soybean seeds (Glycine-max (L.) Merr.) by X-ray diffraction indicated that even in the dehydrated state the lipids retained a lamellar (bilayer) configuration. As the degree of hydration was raised, evidence

Victoria Seewaldt; David A. Priestley; A. Carl Leopold; Gerald W. Feigenson; Federico Goodsaid-Zalduondo

1981-01-01

308

Hit integration for identifying optimal spaced seeds  

Microsoft Academic Search

Background: Introduction of spaced speeds opened a way of sensitivity improvement in homology search without loss of search speed. Since then, the efforts of finding optimal seed which maximizes the sensitivity have been continued today. The sensitivity of a seed is generally computed by its hit probability. However, the limitation of hit probability is that it computes the sensitivity only

Won-Hyoung Chung; Seong-Bae Park

2010-01-01

309

Supercritical fluid extraction of celery seed oil  

Microsoft Academic Search

The supercritical fluid extraction of oil from milled celery seeds, using CO2 as a solvent, is presented in this study. The effect of the process parameters — pressure and temperature of extraction, particle size of celery seeds and flow rate of CO2 — on the extraction rate was examined in a series of experiments. The results indicated a significant increase

I. Papamichail; V. Louli; K. Magoulas

2000-01-01

310

The conservation physiology of seed dispersal  

PubMed Central

At a time when plant species are experiencing increasing challenges from climate change, land-use change, harvesting and invasive species, dispersal has become a very important aspect of plant conservation. Seed dispersal by animals is particularly important because some animals disperse seeds to suitable sites in a directed fashion. Our review has two aims: (i) to highlight the various ways plant dispersal by animals can be affected by current anthropogenic change and (ii) to show the important role of plant and (particularly) animal physiology in shaping seed–dispersal interactions. We argue that large-bodied seed dispersers may be particularly important for plant conservation because seed dispersal of large-seeded plants is often more specialized and because large-bodied animals are targeted by human exploitation and have smaller population sizes. We further argue that more specialized seed-dispersal systems on island ecosystems might be particularly at risk from climate change both owing to small population sizes involved but also owing to the likely thermal specialization, particularly on tropical islands. More generally, the inherent vulnerability of seed-dispersal mutualisms to disruption driven by environmental change (as well as their ubiquity) demands that we continue to improve our understanding of their conservation physiology.

Ruxton, Graeme D.; Schaefer, H. Martin

2012-01-01

311

Students Educating Each Other about Discrimination (SEED).  

ERIC Educational Resources Information Center

This manual is for the Students Educating Each Other about Discrimination (SEED) program and describes its philosophy and curriculum. This curriculum was approved by the Ann Arbor (Michigan) Public Schools School Board. SEED tries to eliminate most forms of discrimination through a program in which high school students encourage sixth graders to…

Thornton, Miguel E.; And Others

312

[Seeds latency of Stylosanthes hamata (Leguminosae) and its relation with morphology of the seed-coat].  

PubMed

The seed of Stylosanthes hamata is characterized by it's a high level of dormancy, which is imposed by seed-coat impermeability to water entry (harseededness or hard-seed condition). The level of hardseededness between upper and lower articulations of seven diploid and five tetraploid accessions was studied under tropical conditions. Germination tests on naked seeds (relative humidity: 55-65%, constant temperature: 27-30 degrees C, photoperiod: 12/12 hr) showed that hard-seed percentage was, in most cases, over 85% independent of ploidy level and seed position within the fruit. Histochemical analysis indicated that hardseededness in this species was associated with a completely sealed microphile and hilum. This feature was also associated to: a) an epidermis consisting of a palisade-like layer of macrosclereids, b) a like-line at the outermost region of these cells and c) a high concentration of hydrophobic compounds located all across the seed-coat. PMID:11795157

Castillo, R; Guenni, O

2001-03-01

313

Wheat and barley seed systems in Ethiopia and Syria  

Microsoft Academic Search

Keywords: Wheat,Triticum<\\/span>spp<\\/span>., Barley,Hordeum<\\/span>vulgare<\\/span> L., Seed Systems, Formal Seed Sector, Informal Seed Sector, National Seed Program, Seed Source, Seed Selection, Seed Management, Seed Quality, Genetic Diversity, Ethiopia, Syria<\\/o:p><\\/ins><\\/span><\\/span>

seed'' attosecond pulse and a control ir field, we propose a scheme for generating secondary attosecond pulses with a high degree of control of their characteristics. By solving the time-dependent Schroedinger equation for a model pre-dissociated molecule (H{sub 2}{sup +}) irradiated by the control ir field and seed xuv pulse, we demonstrate that one can generate such well-controlled secondary attosecond pulses by achieving frequency tuning and up-shifting and control on the chirp of the secondary pulses, which can even be significantly shorter than the seed. We also show that their characteristics can be accurately predicted with a simple classical approach.

Foerre, Morten [Department of Physics and Technology, University of Bergen, N-5007 Bergen (Norway); Centre Lasers Intenses et Applications, Universite Bordeaux-CNRS-CEA, F-33405 Talence Cedex (France); Mevel, Eric; Constant, Eric [Centre Lasers Intenses et Applications, Universite Bordeaux-CNRS-CEA, F-33405 Talence Cedex (France)

2011-02-15

319

[Evaluation of the consequences of stress factors on plant seeds growing in a 30-km zone of Balakovo AES].  

PubMed

The effect of stress factors (small doses of radiation and maximum temperatures in the econiche of the tested plants (tmax)) as well as aging on pea seeds, both acting independently and in combination, is estimated. Here we evaluate the influence of oxidizing stress on pea seeds in the laboratory (gamma-irradiated with 7 cGy at 0.3-19.1 cGy/h, tmax approximately 30-32 degrees C) and on natural plantain seeds collected in a 30-km zone of NPP (radiation exposure approximately 15 R/h, tmax approximately 38-40 degrees C). We have mathematically modeled CAs frequencies in root seedlings meristeme by invoking an enhancing factor transmitted from cell to cell. It is shown under the stress conditions: 1) CA frequency decreases whereas the fraction of inviable seeds (IS) increases, the dependence of IS on CA frequency being inversed; 2) a stimulation of proliferation of cell was observed; 3) a bystander effect appears; 4) antioxidative status (AOS) of seeds influences on adaptation on the all levels of the organization; 5) IS increases up to 73-80% under the combined effect of radiation and heat stresses. PMID:15060947

Korogodina, V L; Bamblevski?, V P; Grishina, I V; Gustova, M V; Dzhavadova, V; Zueva, M V; Korogodin, V I; Lozovskaia, E L; Malikov, A N; Maslov, O D; Mel'nikova, L A; Stepanchuk, V P; Florko, B V; Shliakhtin, G V

2004-01-01

320

Anomalous, extreme weather disrupts obligate seed dispersal mutualism: snow in a subtropical forest ecosystem.  

PubMed

Ongoing global climate change is predicted to increase the frequency and magnitude of extreme weather events, impacting population dynamics and community structure. There is, however, a critical lack of case studies considering how climatic perturbations affect biotic interactions. Here, we document how an obligate seed dispersal mutualism was disrupted by a temporally anomalous and meteorologically extreme interlude of unseasonably frigid weather, with accompanying snowstorms, in subtropical China, during January-February 2008. Based on the analysis of 5892 fecal samples (representing six mammalian seed dispersers), this event caused a substantial disruption to the relative seed dispersal function for the raisin tree Hovenia dulcis from prestorm 6.29 (2006) and 11.47 (2007), down to 0.35 during the storm (2008). Crucially, this was due to impacts on mammalian seed dispersers and not due to a paucity of fruit, where 4.63 fruit per branch were available in January 2008, vs. 3.73 in 2006 and 3.58 in 2007. An induced dietary shift occurred among omnivorous carnivores during this event, from the consumption fruit to small mammals and birds, reducing their role in seed dispersal substantially. Induced range shift extinguished the functionality of herbivorous mammals completely, however, seed dispersal function was compensated in part by three omnivorous carnivores during poststorm years, and thus while the mutualism remained intact it was enacted by a narrower assemblage of species, rendering the system more vulnerable to extrinsic perturbations. The storm's extended effects also had anthropogenic corollaries - migrating ungulates becoming exposed to heightened levels of illegal hunting - causing long-term modification to the seed dispersal community and mutualism dynamics. Furthermore, degraded forests proved especially vulnerable to the storm's effects. Considering increasing climate variability and anthropogenic disturbance, the impacts of such massive, aberrant events warrant conservation concern, while affording unique insights into the stability of mutualisms and the processes that structure biodiversity and mediate ecosystem dynamics. PMID:23640765

Zhou, Youbing; Newman, Chris; Chen, Jin; Xie, Zongqiang; Macdonald, David W

2013-09-01

321

Timing of seed dispersal generates a bimodal seed bank depth distribution  

USGS Publications Warehouse

The density of soil seed banks is normally highest at the soil surface and declines monotonically with depth. Sometimes, for a variety of reasons, peak density occurs below the surface but, except in severely disturbed soils, it is generally true that deeper seeds are older. In seasonally dry habitats that develop deep soil cracks during the dry season, it is possible that some seeds fall down cracks and rapidly become deeply buried. We investigated this possibility for three dominant clonal perennials (Scirpus maritimus, S. litoralis, and Juncus subulatus) in the Don??ana salt marsh, a nontidal marsh with a Mediterranean climate located in southwest Spain. Two species, which shed most of their seed during the dry season and have seeds with low buoyancy, had bimodal viable seed depth distributions, with peak densities at the surface and at 16-20 cm. A third species, which shed most seeds after soil cracks had closed and had seeds with high buoyancy, had viable seeds only in surface soil. Bimodal seed bank depth distributions may be relatively common in seasonally dry habitats with fine-textured soils, but their ecological significance has not been investigated.

Espinar, J. L.; Thompson, K.; Garcia, L. V.

2005-01-01

322

Grazing impact on desert plants and soil seed banks: Implications for seed-eating animals  

NASA Astrophysics Data System (ADS)

We assess whether the knowledge of livestock diet helps to link grazing effects with changes in plant cover and soil seed bank size, aiming at inferring the consequences of grazing on seed-eating animals. Specifically, we test whether continuous and heavy grazing reduce the cover, number of reproductive structures and seed reserves of the same grass species whose seeds are selected and preferred by granivorous animals in the central Monte desert, Argentina. Grass cover and the number of grass spikes usually diminished under grazing conditions in the two localities studied (Telteca and Ñacuñán), and soil seed bank was consistently reduced in all three years evaluated owing to a decline of perennial grass and forb seeds. In particular, the abundance of those seeds selected and preferred by birds and ants (in all cases grass species) declined 70-92% in Ñacuñán, and 52-72% in Telteca. Reduction of perennial grass cover and spike number in grazed sites reinforced the causal link between livestock grazing and the decline of grass soil seed reserves throughout failed plant reproduction. Grass seed bank depletion suggests that grazing may trigger a "cascade" of mechanisms that affect the abundance and persistence of valuable fodder species as well as the availability of seed resources for granivorous animals.

Pol, Rodrigo G.; Sagario, M. Cecilia; Marone, Luis

2014-02-01

323

Colonization of citrus seed coats by 'Candidatus Liberibacter asiaticus': implications for seed transmission of the bacterium.  

PubMed

Huanglongbing is an economically damaging disease of citrus associated with infection by 'Candidatus Liberibacter asiaticus'. Transmission of the organism via infection of seeds has not been demonstrated but is a concern since some citrus varieties, particularly those used as rootstocks in commercial plantings are propagated from seed. We compared the incidence of detection of 'Ca. Liberibacter asiaticus' DNA in individual fruit peduncles, seed coats, seeds, and in germinated seedlings from 'Sanguenelli' sweet orange and 'Conners' grapefruit fruits sampled from infected trees. Using real-time quantitative PCR (qPCR) we detected pathogen DNA in nucleic acid extracts of 36 and 100% of peduncles from 'Sanguenelli' and from 'Conners' fruits, respectively. We also detected pathogen DNA in extracts of 37 and 98% of seed coats and in 1.6 and 4% of extracts from the corresponding seeds of 'Sanguenelli' and 'Conners', respectively. Small amounts of pathogen DNA were detected in 10% of 'Sanguenelli' seedlings grown in the greenhouse, but in none of 204 extracts from 'Conners' seedlings. Pathogen DNA was detected in 4.9% and in 89% of seed coats peeled from seeds of 'Sanguenelli' and 'Conners' which were germinated on agar, and in 5% of 'Sanguenelli' but in none of 164 'Conners' seedlings which grew from these seeds on agar. No pathogen DNA was detected in 'Ridge Pineapple' tissue at 3 months post-grafting onto 'Sanguenelli' seedlings, even when pathogen DNA had been detected initially in the 'Sanguenelli' seedling. Though the apparent colonization of 'Conners' seeds was more extensive and nearly uniform compared with 'Sanguenelli' seeds, no pathogen DNA was detected in 'Conners' seedlings grown from these seeds. For either variety, no association was established between the presence of pathogen DNA in fruit peduncles and seed coats and in seedlings. PMID:21714779

Hilf, Mark E

2011-10-01

324

Single-mode operation characteristics of a self-injection seeded Fabry-Perot laser diode with distributed feedback from a fiber grating  

Microsoft Academic Search

We study the operational characteristics of a self-injection seeded laser diode in an external cavity consisting of a fiber Bragg grating. The distributed feedback (DFB) of light in the grating provides an additional tolerance of frequency detuning in mode selection. The spectral characteristics at different operating frequencies and feedback rates have been investigated. Wavelength tuning has also been realized by

Y. Zhao; C. Shu

1997-01-01

325

Converting Frequency Responses to Daily Frequency  

Cancer.gov

Frequency information on the DSQ in NHANES 2009-2010 was collected using a rate and time unit (e.g., 3 times per week). A different response format consisting of a set number of frequency categories is used in the self-administered paper questionnaire (link to questionnaire) ,. In both cases, the frequency responses are converted to a common unit of time, i.e. times per day.

326

Triple Modulator-Chicane Scheme for Seeding Sub-Nanometer X-Ray Free Electron Lasers  

SciTech Connect

We propose a novel triple modulator-chicane (TMC) scheme to convert external input seed to shorter wavelengths. In the scheme high power seed lasers are used in the first and third modulator while only very low power seed is used in the second modulator. By properly choosing the parameters of the lasers and chicanes, we show that ultrahigh harmonics can be generated in the TMC scheme while simultaneously keeping the energy spread growth much smaller than beam's initial slice energy spread. As an example we show the feasibility of generating significant bunching at 1 nm and below from a low power ({approx} 100 kW) high harmonic generation seed at 20 nm assisted by two high power ({approx} 100 MW) UV lasers at 200 nm while keeping the energy spread growth within 40%. The supreme up-frequency conversion efficiency of the proposed TMC scheme together with its unique advantage in maintaining beam energy spread opens new opportunities for generating fully coherent x-rays at sub-nanometer wavelength from external seeds.

Xiang, Dao; Stupakov, Gennady; /SLAC

2011-07-06

327

Effects of rice seed surface sterilization with hypochlorite on inoculated Burkholderia vietnamiensis.  

PubMed

When a combination of hydrogen peroxide and hypochlorite was used to surface sterilize rice seeds, a 10(2)- to 10(4)-fold decrease in CFU was observed during the first 15 h after inoculation of the rice rhizosphere organism Burkholderia vietnamiensis TVV75. This artifact could not be eliminated simply by rinsing the seeds, even thoroughly, with sterile distilled water. When growth resumed, a significant increase in the frequency of rifampin- and nalidixic acid-resistant mutants in the population was observed compared to the control without seeds. This phenomenon was a specific effect of hypochlorite; it was not observed with hydrogen peroxide alone. It was also not observed when the effect of hypochlorite was counteracted by sodium thiosulfate. We hypothesized that the hypochlorite used for disinfection reacted with the rice seed surface, forming a chlorine cover which was not removed by rinsing and generated mutagenic chloramines. We studied a set of rifampin- and nalidixic acid-resistant mutants obtained after seed surface sterilization. The corresponding rpoB and gyrA genes were amplified and sequenced to characterize the induced mutations. The mutations in five of seven nalidixic acid-resistant mutants and all of the rifampin-resistant mutants studied were found to correspond to single amino acid substitutions. Hypochlorite surface sterilization can thus be a source of artifacts when the initial bacterial colonization of a plant is studied. PMID:11425720

Miché, L; Balandreau, J

2001-07-01

328

Oxygen requirement of germinating flax seeds.  

PubMed

Plant experiments in earth orbit are typically prepared on the ground and germinated in orbit to study gravity effects on the developing seedlings. Germination requires the breakdown of storage compounds, and this metabolism depends upon respiration, making oxygen one of the limiting factors in seed germination. In microgravity lack of run-off of excess water requires careful testing of water dispensation and oxygen availability. In preparation for a shuttle experiment (MICRO on STS-107) we studied germination and growth of flax (Linum usitatissimum L.) seedlings in the developed hardware (Magnetic Field Chamber, MFC). We tested between four to 32 seeds per chamber (air volume=14 mL) and after 36 h measured the root length. At 90 microliters O2 per seed (32 seeds/chamber), the germination decreased from 94 to 69%, and the root length was reduced by 20%, compared to 8 seeds per chamber. Based on the percent germination and root length obtained in controlled gas mixtures between 3.6 and 21.6% O2 we determined the lower limit of reliable germination to be 10 vol. % O2 at atmospheric pressure. Although the oxygen available in the MFC's can support the intended number of seeds, the data show that seed storage and microgravity-related limitations may reduce germination. PMID:14686434

Kuznetsov, Oleg A; Hasenstein, K H

2003-01-01

329

Oxygen requirement of germinating flax seeds  

NASA Astrophysics Data System (ADS)

Plant experiments in earth orbit are typically prepared on the ground and germinated in orbit to study gravity effects on the developing seedlings. Germination requires the breakdown of storage compounds, and this metabolism depends upon respiration, making oxygen one of the limiting factors in seed germination. In microgravity lack of run-off of excess water requires careful testing of water dispensation and oxygen availability. In preparation for a shuttle experiment (MICRO on STS-107) we studied germination and growth of flax ( Linum usitatissimum L.) seedlings in the developed hardware (Magnetic Field Chamber, MFC). We tested between four to 32 seeds per chamber (air volume = 14 mL) and after 36 h measured the root length. At 90 ?l O 2 per seed (32 seeds/chamber), the germination decreased from 94 to 69%, and the root length was reduced by 20%, compared to 8 seeds per chamber. Based on the percent germination and root length obtained in controlled gas mixtures between 3.6 and 21.6% O 2 we determined the lower limit of reliable germination to be 10 vol. % O 2 at atmospheric pressure. Although the oxygen available in the MFC's can support the intended number of seeds, the data show that seed storage and microgravity-related limitations may reduce germination.

Kuznetsov, Oleg A.; Hasenstein, K. H.

2003-05-01

330

Photoinduced Seed Germination of Oenothera biennis L  

PubMed Central

The postinduction period of Oenothera biennis L. seed germination was examined by temperature treatments. For all experiments, seeds received a standard 24 hour/24°C preinduction period and 12 hour/32°C photoinduction period. Germination is inhibited by postinduction temperatures above 32°C. When seeds are briefly incubated at 44°C and then transferred to 28°C, they germinate at a much lower percentage than 28°C controls. When thermally inhibited seeds are placed in the dark at 28°C for 20 hours, they can be promoted to germinate by a single pulse of red light. Seeds incubated at 12°C or below immediately after photoinduction enter a lag period in which they germinate slowly or not at all for a long time and then resume germination. The length of the lag period is exponentially related to the postinduction temperature. When seeds are incubated at a low temperature and then transferred to a warm temperature, they germinate much more rapidly than seeds not incubated at a low temperature. A model is proposed which is consistent with these and additional results. In the model, a germination promoter is irreversibly formed from a precursor and the synthesis of the precursor is favored at low temperatures and its degradation is favored at high temperatures.

Ensminger, Peter A.; Ikuma, Hiroshi

1988-01-01

331

Control of Seed Germination by Abscisic Acid  

PubMed Central

The germination process of mustard seeds (Sinapis alba L.) has been characterized by the time courses of water uptake, rupturing of the seed coat (12 hours after sowing), onset of axis growth (18 hours after sowing), and the point of no return, where the seeds lose the ability to survive redesiccation (12 to 24 hours after sowing, depending on embryo part). Abscisic acid (ABA) reversibly arrests embryo development at the brink of radicle growth initiation, inhibiting the water uptake which accompanies embryo growth. Seeds which have been kept dormant by ABA for several days will, after removal of the hormone, rapidly take up water and continue the germination process. Seeds which have been preincubated in water lose the sensitivity to be arrested by ABA after about 12 hours after sowing. This escape from ABA-mediated dormancy is not due to an inactivation of the hormone but to a loss of competence to respond to ABA during the course of germination. The sensitivity to ABA can be restored in these seeds by redrying. It is concluded that a primary action of ABA in inhibiting seed germination is the control of water uptake of the embryo tissues rather than the control of DNA, RNA, or protein syntheses.

Schopfer, P.; Bajracharya, D.; Plachy, C.

1979-01-01

332

Oxygen requirement of germinating flax seeds  

NASA Technical Reports Server (NTRS)

Plant experiments in earth orbit are typically prepared on the ground and germinated in orbit to study gravity effects on the developing seedlings. Germination requires the breakdown of storage compounds, and this metabolism depends upon respiration, making oxygen one of the limiting factors in seed germination. In microgravity lack of run-off of excess water requires careful testing of water dispensation and oxygen availability. In preparation for a shuttle experiment (MICRO on STS-107) we studied germination and growth of flax (Linum usitatissimum L.) seedlings in the developed hardware (Magnetic Field Chamber, MFC). We tested between four to 32 seeds per chamber (air volume=14 mL) and after 36 h measured the root length. At 90 microliters O2 per seed (32 seeds/chamber), the germination decreased from 94 to 69%, and the root length was reduced by 20%, compared to 8 seeds per chamber. Based on the percent germination and root length obtained in controlled gas mixtures between 3.6 and 21.6% O2 we determined the lower limit of reliable germination to be 10 vol. % O2 at atmospheric pressure. Although the oxygen available in the MFC's can support the intended number of seeds, the data show that seed storage and microgravity-related limitations may reduce germination. c2003 Published by Elsevier Ltd on behalf of COSPAR.

Kuznetsov, Oleg A.; Hasenstein, K. H.; Hasentein, K. H. (Principal Investigator)

2003-01-01

333

Frequency doubling in ultralow frequency wave signals  

NASA Astrophysics Data System (ADS)

We report a new theory to explain the long-observed frequency-doubling phenomenon detected in the compressional component of ``high-m'' ultralow-frequency signals seen in the Earth's magnetosphere. We show that the effect is a nonlinear response directly associated with resonant particles. The phase relationship observed between the linear signal and the nonlinear frequency-doubled signal is predicted by the theory. Our explanation and the fit with observation mean that the occurrence of frequency doubling provides critical evidence of the fact that ring current particles drive high-m waves.

Southwood, David J.; Kivelson, Margaret G.

1997-12-01

334

The oxygen requirement of germinating flax seeds  

NASA Astrophysics Data System (ADS)

Experiments for earth orbit are typically prepared on the ground and often germinated in orbit in order to study gravity effects on developing seedlings. Germination requires the breakdown of storage compounds and respiration. In orbit the formation of a water layer around the seed may further limit oxygen availability. Therefore, the oxygen content of the available gas volume is one of the limiting factors for seed germination. In preparation for an upcoming shuttle experiment (MICRO on STS-107) we studied germination and growth of flax (Linum usitatissimum L.) seedlings in the developed hardware. We tested per seed chamber (gas volume = 14 mL, O2 = 2.9 mL) between 4 to 32 seeds glued to germination paper by 1% (w/v) gum guar. A lexan cover and a gasket hermetically sealed each of the eight chambers. For imbibition of the seeds a previously optimized amount of distilled water was dispensed through sealed inlets. The seedlings were allowed to grow for either 32 to 48 h on a clinostat or without microgravity simulation. Then their root length was measured. With 32 seeds per chamber, four times the intended number of seeds for the flight, the germination rate decreased from 94 to 69%, and the root length was reduced by 20%. Experiments on the germination and root length in controlled atmospheres (5, 10, 15 and 21% O2 ) suggest that germination and growth for two days requires about 200 :l of O (1 mL air) per seed. Our2 experiments correlate oxygen dependency from seed mass and germination temperature, and analyze accumulation of gaseous metabolites (supported by NASA grant NAG10-0190).

Kuznetsov, O.; Hasenstein, K.

335

Direct somatic embryogenesis and synthetic seed production from Paulownia elongata.  

PubMed

We have developed a reproducible system for efficient direct somatic embryogenesis from leaf and internodal explants of Paulownia elongata. The somatic embryos obtained were subsequently encapsulated as single embryos to produce synthetic seeds. Several plant growth regulators [6-benzylaminopurine, indole-3-acetic acid, alpha-naphthaleneacetic acid, kinetin and thidiazuron (TDZ)] alone or in combination were tested for their capacity to induce somatic embryogenesis. The highest induction frequencies of somatic embryos were obtained on Murashige and Skoog (MS) medium supplemented with 3% sucrose, 0.6% Phytagel, 500 mg l(-1) casein hydrolysate and 10 mg l(-1) TDZ (medium MS10). Somatic embryos were induced from leaf (69.8%) and internode (58.5%) explants on MS10 medium after 7 days. Subsequent withdrawal of TDZ from the induction medium resulted in the maturation and growth of the embryos into plantlets on MS basal media. The maturation frequency of somatic embryos from leaf and internodal explants was 50.8% and 45.8%, respectively. Subculturing of mature embryos led to their germination on the same medium with a germination frequency of 50.1% and 29.8% from leaf and internode explants, respectively. Somatic embryos obtained directly on leaf explants were used for encapsulation in liquid MS medium containing different concentrations of sodium alginate with a 30-min exposure to 50 m M CaCl(2). A 3% sodium alginate concentration provided a uniform encapsulation of the embryos with survival and germination frequencies of 73.7% and 53.3%, respectively. Storage at 4 degrees C for 30 days or 60 days significantly reduced the survival and complete germination frequencies of both encapsulated and non-encapsulated embryos relative to those of non-stored somatic embryos. However, the survival and germination rates of encapsulated embryos increased following storage at 4 degrees C. After 30 days or 60 days of storage, the survival rates of encapsulated embryos were 67.8% and 53.5% and the germination frequencies were 43.2% and 32.4%, respectively. These systems could be useful for the rapid clonal propagation and dissemination of synthetic seed material of Paulownia elongata. PMID:12827435

Ipekci, Z; Gozukirmizi, N

2003-08-01

336

Competition between meiotic and apomictic pathways during ovule and seed development results in clonality.  

PubMed

Meiotic and apomictic reproductive pathways develop simultaneously in facultative aposporous species, and compete to form a seed as a final goal. This developmental competition was evaluated in tetraploid genotypes of Paspalum malacophyllum in order to understand the low level of sexuality in facultative apomictic populations. Cyto-embryology on ovules, flow cytometry on seeds and progeny tests by DNA fingerprinting were used to measure the relative incidence of each meiotic or apomictic pathway along four different stages of the plant's life cycle, namely the beginning and end of gametogenesis, seed formation and adult offspring. A high variation in the frequencies of sexual and apomictic pathways occurred at the first two stages. A trend of radical decline in realized sexuality was then observed. Sexual and apomictic seeds were produced, but the efficiency of the sexual pathway dropped drastically, and exclusively clonal offspring remained. Both reproductive pathways are unstable at the beginning of development, and only the apomictic one remains functional. Key factors reducing sexuality are the faster growth and parthenogenetic development in the aposporous pathway, and an (epi)genetically negative background related to the extensive gene de-regulation pattern responsible for apomixis. The effects of inbreeding depression during post-fertilization development may further decrease the frequency of effective sexuality. PMID:23127139

Hojsgaard, Diego H; Martínez, Eric J; Quarin, Camilo L

2013-01-01

337

MHD Heat and Seed Recovery Technology Project  

NASA Astrophysics Data System (ADS)

Experimental investigations are being conducted or planned in the following of critical problem areas: (1) corrosion and erosion of refractories and metal alloys; (2) NO/sub x/ behavior in the radiant boiler and secondary combustor; (3) radiant boiler design to meet the multiple requirements of steam generation, NO/sub x/ decomposition, and seed-slag separation; (4) effects of solid or liquid seed deposits on heat transfer and gas flow in the steam and air heaters; (5) formation, growth, and deposition of seed-slag particles, and (6) character of the combustion gas effluents.

Petrick, M.; Johnson, T. R.

1981-07-01

338

Seed dimorphism, nutrients and salinity differentially affect seed traits of the desert halophyte Suaeda aralocaspica via multiple maternal effects  

PubMed Central

Background Maternal effects may influence a range of seed traits simultaneously and are likely to be context-dependent. Disentangling the interactions of plant phenotype and growth environment on various seed traits is important for understanding regeneration and establishment of species in natural environments. Here, we used the seed-dimorphic plant Suaeda aralocaspica to test the hypothesis that seed traits are regulated by multiple maternal effects. Results Plants grown from brown seeds had a higher brown:black seed ratio than plants from black seeds, and germination percentage of brown seeds was higher than that of black seeds under all conditions tested. However, the coefficient of variation (CV) for size of black seeds was higher than that of brown seeds. Seeds had the smallest CV at low nutrient and high salinity for plants from brown seeds and at low nutrient and low salinity for plants from black seeds. Low levels of nutrients increased size and germinability of black seeds but did not change the seed morph ratio or size and germinability of brown seeds. High levels of salinity decreased seed size but did not change the seed morph ratio. Seeds from high-salinity maternal plants had a higher germination percentage regardless of level of germination salinity. Conclusions Our study supports the multiple maternal effects hypothesis. Seed dimorphism, nutrient and salinity interacted in determining a range of seed traits of S. aralocaspica via bet-hedging and anticipatory maternal effects. This study highlights the importance of examining different maternal factors and various offspring traits in studies that estimate maternal effects on regeneration.

2012-01-01

339

?-Irradiation of Seeds and Productivity of Coriander, Coriandrum sativum L  

Microsoft Academic Search

Plant productivity and essential oil quality of coriander (Coriandrum sativuum L. cv. Alekseevsky 247) grown from ?-irradiated seeds was field tested in Bulgaria. The seeds, irradiated with 500 to 1500 rads using Co as the ?-irradiation source, produced plants yielding 14 to 25 percent more seed and 12 to 28 percent more oil than control plants grown from unirradiated seed.

E. A. Jeliazkova; L. E. Craker; V. D. Zheljazkov

1998-01-01

340

Yield and Quality of Seed from Yellow Birch Progenies.  

National Technical Information Service (NTIS)

Seed yield in 8- and 9-year-old yellow birch varied among families and years but averaged more than 1,500 seeds per tree. Long catkins contained more seed than short ones. Seed quality was poor due to insufficient pollination and to differences among tree...

K. E. Clausen

1980-01-01

341

Structural mechanics of seed deterioration: Standing the test of time  

Microsoft Academic Search

Seeds die inevitably but unexpectedly during storage and current understanding of seed quality and storage conditions do not allow reliable means to predict or prevent this critical problem. Chemical degradation of seed components likely occurs through oxidative damage, but the rate of these reactions is dominated by properties of seed that are affected by temperature and moisture. These visco-elastic properties

Christina Walters; Daniel Ballesteros; Veronica A. Vertucci

2010-01-01

342

EMISSION OF VOLATILE COMPOUNDS BY SEEDS UNDER DIFFERENT ENVIRONMENTAL CONDITIONS  

EPA Science Inventory

Small mammals locate buried wet seeds more efficiently than buried dry seeds. This may be attributable to emission of volatile compounds by the seeds. To test this hypothesis I measured emission of volatile compounds from seeds of three plant species (Pinus contorta, Purshia tr...

343

Burial increases seed longevity of two Artemisia tridentata (Asteraceae) subspecies  

USGS Publications Warehouse

Premise of the study: Seed longevity and persistence in soil seed banks may be especially important for population persistence in ecosystems where opportunities for seedling establishment and disturbance are unpredictable. The fire regime, an important driver of population dynamics in sagebrush steppe ecosystems, has been altered by exotic annual grass invasion. Soil seed banks may play an active role in postfire recovery of the foundation shrub Artemisia tridentata, yet conditions under which seeds persist are largely unknown. Methods: We investigated seed longevity of two Artemisia tridentata subspecies in situ by retrieving seed bags that were placed at varying depths over a 2 yr period. We also sampled naturally dispersed seeds in litter and soil immediately after seed dispersal and before flowering in subsequent seasons to estimate seed persistence. Key results: After 24 mo, seeds buried at least 3 cm below the soil surface retained 30–40% viability whereas viability of seeds on the surface and under litter declined to 0 and Artemisia tridentata has the potential to form a short-term soil seed bank that persists longer than has been commonly assumed, and that burial is necessary for seed longevity. Use of seeding techniques that promote burial of some seeds to aid in formation of a soil seed bank may increase restoration potential.

Wijayratne, Upekala C.; Pyke, David A.

2012-01-01

344

7 CFR 361.5 - Sampling of seeds.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Sampling of seeds. 361.5 Section 361.5 Agriculture ...SERVICE, DEPARTMENT OF AGRICULTURE IMPORTATION OF SEED AND SCREENINGS UNDER THE FEDERAL SEED ACT § 361.5 Sampling of seeds....

2009-01-01

345

7 CFR 361.5 - Sampling of seeds.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Sampling of seeds. 361.5 Section 361.5 Agriculture ...SERVICE, DEPARTMENT OF AGRICULTURE IMPORTATION OF SEED AND SCREENINGS UNDER THE FEDERAL SEED ACT § 361.5 Sampling of seeds....

2010-01-01

346

Insect visitation to flowering hybrid carrot seed crops  

Microsoft Academic Search

Although there is some literature published on insect visitation to open pollinated carrot seed crops in several regions around the world, there is none in Australasia and none on insect visitation to hybrid carrot seed crops worldwide. With a growing hybrid carrot seed crop industry in southern Australia and New Zealand, a survey of insect visitation to carrot seed crops

A Gaffney; G R Allen; P H Brown

2011-01-01

347

Thieving rodents as substitute dispersers of megafaunal seeds  

PubMed Central

The Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other’s buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees.

Jansen, Patrick A.; Hirsch, Ben T.; Emsens, Willem-Jan; Zamora-Gutierrez, Veronica; Wikelski, Martin; Kays, Roland

2012-01-01

348

Thieving rodents as substitute dispersers of megafaunal seeds.  

PubMed

The Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other's buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees. PMID:22802644

Jansen, Patrick A; Hirsch, Ben T; Emsens, Willem-Jan; Zamora-Gutierrez, Veronica; Wikelski, Martin; Kays, Roland

2012-07-31

349

Power and frequency-noise characteristics of an Yb-doped fiber amplifier and actuators for stabilization  

Microsoft Academic Search

The interferometric gravitational-wave detector LISA requires laser sources with 1W of output power and low frequency and power noise as well as actuators for further power and frequency stabilization. We report on power- and frequency noise measurements of an Yb-doped fiber amplifier seeded by a nonplanar ring oscillator and identify actuators for both power and frequency stabilization of such a

Michael Tröbs; Peter Weßels; Carsten Fallnich

2005-01-01

350

Using a linearly chirped seed suppresses SBS in high-power fiber amplifiers, allows coherent combination, and enables long delivery fibers  

NASA Astrophysics Data System (ADS)

When seeding a high power fiber amplifier with a frequency-chirped seed, the backward Brillouin scattering can be kept at the spontaneous level because the coherent laser/Stokes interaction is interrupted. Operating a conventional vertical cavity surface-emitting diode laser in an optoelectronic feedback loop can yield a linear frequency chirp of ~1016 Hz/s at a constant output power. The simple and deterministic variation of phase with time preserves temporal coherence, in the sense that it is straightforward to coherently combine multiple amplifiers despite a large length mismatch. The seed bandwidth as seen by the counter-propagating SBS is large, and also increases linearly with fiber length, resulting in a nearly-length-independent SBS threshold. Experimental results at the 600W level will be presented. The impact of a chirped seed on multimode instability is also addressed theoretically.

White, Jeffrey O.; Petersen, Eliot; Edgecumbe, J.; Rakuljic, George; Satyan, Naresh; Vasilyev, Arseny; Yariv, A.

2014-03-01

351

Effects of Seed Roasting on Tocopherols, Carotenoids, and Oxidation in Mustard Seed Oil During Heating  

Microsoft Academic Search

Seed roasting is practiced in the mustard oil industry in some areas of the world, and can affect the physicochemical properties\\u000a of the oil for further applications. This research studied the differences in oxidative stability, tocopherols, and carotenoids\\u000a during heating at 160 °C between oil extracted from roasted mustard seeds and that from unroasted seeds. The content of free\\u000a fatty acids,

Bipin Vaidya; Eunok Choe

2011-01-01

352

Effect of GA3 Treatment on Seed Development and Seed-Related Gene Expression in Grape  

PubMed Central

Background The phytohormone gibberellic acid (GA3) is widely used in the table grape industry to induce seedlessness in seeded varieties. However, there is a paucity of information concerning the mechanisms by which GAs induce seedlessness in grapes. Methodology/Principal Findings In an effort to systematically analyze the cause of this GA3-induced seed abortion, we conducted an in depth characterization of two seeded grape cultivars (‘Kyoho’ and ‘Red Globe’), along with a seedless cultivar (‘Thompson Seedless’), following treatment with GA3. In a similar fashion to the seedless control, which exhibited GA3-induced abortion of the seeds 9 days after full bloom (DAF), both ‘Kyoho’ and ‘Red Globe’ seeded varieties exhibited complete abortion of the seeds 15 DAF when treated with GA3. Morphological analyses indicated that while fertilization appeared to occur normally following GA3 treatment, as well as in the untreated seedless control cultivar, seed growth eventually ceased. In addition, we found that GA3 application had an effect on redox homeostasis, which could potentially cause cell damage and subsequent seed abortion. Furthermore, we carried out an analysis of antioxidant enzyme activities, as well as transcript levels from various genes believed to be involved in seed development, and found several differences between GA3-treated and untreated controls. Conclusion Therefore, it seems that the mechanisms driving GA3-induced seedlessness are similar in both seeded and seedless cultivars, and that the observed abortion of seeds may result at least in part from a GA3-induced increase in cell damage caused by reactive oxygen species, a decrease in antioxidant enzymatic activities, and an alteration of the expression of genes related to seed development.

Cheng, Chenxia; Xu, Xiaozhao; Singer, Stacy D.; Li, Jun; Zhang, Hongjing; Gao, Min; Wang, Li; Song, Junyang; Wang, Xiping

2013-01-01

353

Gastropod Seed Dispersal: An Invasive Slug Destroys Far More Seeds in Its Gut than Native Gastropods  

PubMed Central

Seed dispersal is one of the most important mechanisms shaping biodiversity, and animals are one of the key dispersal vectors. Animal seed dispersal can directly or indirectly be altered by invasive organisms through the establishment of new or the disruption of existing seed dispersal interactions. So far it is known for a few gastropod species that they ingest and defecate viable plant seeds and consequently act as seed dispersers, referred to as gastropodochory. In a multi-species experiment, consisting of five different plant species and four different gastropod species, we tested with a fully crossed design whether gastropodochory is a general mechanism across native gastropod species, and whether it is altered by the invasive alien slug species Arion lusitanicus. Specifically, we hypothesized that a) native gastropod species consume the seeds from all tested plant species in equal numbers (have no preference), b) the voracious invasive alien slug A. lusitanicus – similarly to its herbivore behaviour – consumes a higher amount of seeds than native gastropods, and that c) seed viability is equal among different gastropod species after gut passage. As expected all tested gastropod species consumed all tested plant species. Against our expectation there was a difference in the amount of consumed seeds, with the largest and native mollusk Helix pomatia consuming most seeds, followed by the invasive slug and the other gastropods. Seed damage and germination rates did not differ after gut passage through different native species, but seed damage was significantly higher after gut passage through the invasive slug A. lusitanicus, and their germination rates were significantly reduced.

Blattmann, Tamara; Boch, Steffen; Turke, Manfred; Knop, Eva

2013-01-01

354

Device for isolation of seed crystals during processing of solution  

DOEpatents

A device is described for isolation of seed crystals during processing of solutions. The device enables a seed crystal to be introduced into the solution without exposing the solution to contaminants or to sources of drying and cooling. The device constitutes a seed protector which allows the seed to be present in the growth solution during filtration and overheating operations while at the same time preventing the seed from being dissolved by the under saturated solution. When the solution processing has been completed and the solution cooled to near the saturation point, the seed protector is opened, exposing the seed to the solution and allowing growth to begin. 3 figs.

Montgomery, K.E.; Zaitseva, N.P.; Deyoreo, J.J.; Vital, R.L.

1999-05-18

355

Plants as seed traps: inter-specific interference with dispersal  

NASA Astrophysics Data System (ADS)

Established plants may disrupt patterns of seed deposition by physically trapping dispersing seed. In this study we quantified seed trapping at very fine spatial scales, by measuring seed fall of two ericaceous dwarf shrub species at a range of distances from allospecific shrubs within a matrix of short grass vegetation. Next to allospecific bushes, seed deposition densities of Calluna vulgaris and Erica cinerea were between 7- and 20-fold higher than those in the short grass. This increase is comparable to deposition densities next to conspecific bushes, caused by local dispersal, which were 19-33-fold greater than the background seed rain. Seed densities decayed rapidly with distance from the allospecific bush, so that in general the bush's influence on deposition extended <0.1 m. By causing localised, extreme peaks in seed density around established plants, seed trapping could have large effects on the fitness of plants dispersing seed and on the spatial pattern of recruitment across plant communities.

Bullock, James M.; Moy, Ibby L.

2004-03-01

356

Injection-seeded pulsed Ti:sapphire laser with novel stabilization scheme and capability of dual-wavelength operation  

Microsoft Academic Search

A gain-switched, single-frequency titanium-sapphire laser for atmospheric humidity measurements using the differential absorption lidar technique operating in the 820 nm wavelength region is described. The laser is pumped by a frequency-doubled, flashlamp-pumped Nd:YAG laser at a repetition rate of 50 Hz and injection seeded by two external-cavity-diode lasers. The system yields pulses with an energy of 15 mJ and high

Klaus Ertel; Holger Linné; Jens Bösenberg

2005-01-01

357

Induction of 9-cis-epoxycarotenoid dioxygenase in Arabidopsis thaliana seeds enhances seed dormancy  

PubMed Central

Full understanding of mechanisms that control seed dormancy and germination remains elusive. Whereas it has been proposed that translational control plays a predominant role in germination, other studies suggest the importance of specific gene expression patterns in imbibed seeds. Transgenic plants were developed to permit conditional expression of a gene encoding 9-cis-epoxycarotenoid dioxygenase 6 (NCED6), a rate-limiting enzyme in abscisic acid (ABA) biosynthesis, using the ecdysone receptor-based plant gene switch system and the ligand methoxyfenozide. Induction of NCED6 during imbibition increased ABA levels more than 20-fold and was sufficient to prevent seed germination. Germination suppression was prevented by fluridone, an inhibitor of ABA biosynthesis. In another study, induction of the NCED6 gene in transgenic seeds of nondormant mutants tt3 and tt4 reestablished seed dormancy. Furthermore, inducing expression of NCED6 during seed development suppressed vivipary, precocious germination of developing seeds. These results indicate that expression of a hormone metabolism gene in seeds can be a sole determinant of dormancy. This study opens the possibility of developing a robust technology to suppress or promote seed germination through engineering pathways of hormone metabolism.

Martinez-Andujar, Cristina; Ordiz, M. Isabel; Huang, Zhonglian; Nonogaki, Mariko; Beachy, Roger N.; Nonogaki, Hiroyuki

2011-01-01

358

Timing of fire relative to seed development controls availability of non-serotinous aerial seed banks  

NASA Astrophysics Data System (ADS)

The existence of non-serotinous, non-sprouting species in fire regimes where serotiny confers an adaptive advantage is puzzling, particularly when these species recruit poorly from soil seed banks or from burn edges. In this paper, white spruce (Picea glauca (Moench) Voss) was used to show that the timing of fire relative to seed development can control aerial seed bank availability for non-serotinous species. To estimate seed survival in closed cones during crown fires, cone heating was simulated using a one-dimensional conduction model implemented in a computational fluid dynamics (Navier-Stokes) fire spread model. To quantify the area burned when germinable seed would be contained in closed cones, empirical fire occurrence and seed development (germinability and cone opening) data were compared for multiple locations across the white spruce range. Approximately 12% of cones contained viable seed following crown fire simulations (0.072 m s-1 mean spread rate; 9147 kW m-1 mean intensity), and roughly half of the historical area burned resulted from fires that occurred when closed cones would contain germinable seed. Post-fire recruitment from in situ aerial seed banks can occur for non-serotinous species, and may be an important cause of their existence in fire regimes to which they otherwise seem poorly suited.

Michaletz, S. T.; Johnson, E. A.; Mell, W. E.; Greene, D. F.

2012-11-01

359

Pesticide-laden dust emission and drift from treated seeds during seed drilling: a review.  

PubMed

Dressing seeds with pesticides to control pests is a widespread practice with important advantages. Recent incidents of bee losses, however, have directed attention to the emission of abraded pesticide-coated seed particles to the environment during sowing. This phenomenon of drift of pesticide dust can lead to pesticide contamination of air, water and other natural resources in crop-growing areas. This review article presents the state of the art of the phenomenon of dust emission and drift from pesticide seed dressing during sowing and its consequences. Firstly, pesticide seed treatment is defined and its pros and cons are set out, with the focus on dust, dust emission and dust drift from pesticide-coated seed. The factors affecting emission of pesticide dust (e.g. seed treatment quality, seed drilling technology and environmental conditions) are considered, along with its possible effects. The measuring techniques and protocols and models currently in use for calculating the behaviour of dust are reviewed, together with their features and limitations. Finally, possible mitigation measures are discussed, such as improving the seed quality and the use of modified seed drilling technology, and an overview of regulations and stewardship activities is given. PMID:23456984

Nuyttens, David; Devarrewaere, Wouter; Verboven, Pieter; Foqué, Dieter

2013-05-01

360

Prospects for Successful Manila Clam Seeding.  

National Technical Information Service (NTIS)

The report summarizes the cooperative effort among several agencies investigating a culture technique for planting hatchery-reared seed Manila clams on Puget Sound beaches. The study investigates the feasibility of this method of culture and searches for ...

K. K. Chew

1975-01-01

361

Effects of Air Temperature on Seed Germination  

NSDL National Science Digital Library

This activity begins as a classroom investigation, but may extend to a field investigation where students will determine the effects of air temperature on seed germination. This is accomplished by developing investigative questions, recording, and analyzing data.

Macarthur, Amy

362

Calculations Pertaining to Hygroscopic Seeding with Flares.  

NASA Astrophysics Data System (ADS)

Some possible effects of hygroscopic seeding with flares are explored by calculating how such seeding would modify the initial size distribution of cloud droplets and the subsequent evolution of that size distribution by coalescence. To be representative of recent experiments in South Africa, the calculations emphasize the effects of hygroscopic particles that can be produced by flares, instead of the larger particles used in most past hygroscopic-seeding experiments. Parcel calculations representing simultaneous condensation and coalescence suggest that the formation of rain through the warm-rain process can be accelerated significantly by the addition of such hygroscopic particles. Some observations of the effects of hygroscopic material near cloud base support at least the early stages of the calculations. The results suggest that the positive effects being obtained in the South African experiment may occur through such acceleration of the warm-rain process. Possible cloud-seeding applications and climate implications are discussed.

Cooper, William A.; Bruintjes, Roelof T.; Mather, Graeme K.

1997-11-01

363

Adaptive seeds tame genomic sequence comparison  

PubMed Central

The main way of analyzing biological sequences is by comparing and aligning them to each other. It remains difficult, however, to compare modern multi-billionbase DNA data sets. The difficulty is caused by the nonuniform (oligo)nucleotide composition of these sequences, rather than their size per se. To solve this problem, we modified the standard seed-and-extend approach (e.g., BLAST) to use adaptive seeds. Adaptive seeds are matches that are chosen based on their rareness, instead of using fixed-length matches. This method guarantees that the number of matches, and thus the running time, increases linearly, instead of quadratically, with sequence length. LAST, our open source implementation of adaptive seeds, enables fast and sensitive comparison of large sequences with arbitrarily nonuniform composition.

Kielbasa, Szymon M.; Wan, Raymond; Sato, Kengo; Horton, Paul; Frith, Martin C.

2011-01-01

364

Shaping metal nanocrystals through epitaxial seeded growth  

SciTech Connect

Morphological control of nanocrystals has becomeincreasingly important, as many of their physical and chemical propertiesare highly shape-dependent. Nanocrystal shape control for both single andmultiple material systems, however, remains fairly empirical andchallenging. New methods need to be explored for the rational syntheticdesign of heterostructures with controlled morphology. Overgrowth of adifferent material on well-faceted seeds, for example, allows for the useof the defined seed morphology to control nucleation and growth of thesecondary structure. Here, we have used highly faceted cubic Pt seeds todirect the epitaxial overgrowth of a secondary metal. We demonstrate thisconcept with lattice matched Pd to produce conformal shape-controlledcore-shell particles, and then extend it to lattice mismatched Au to giveanisotropic growth. Seeding with faceted nanocrystals may havesignificant potential towards the development of shape-controlledheterostructures with defined interfaces.

Habas, Susan E.; Lee, Hyunjoo; Radmilovic, Velimir; Somorjai,Gabor A.; Yang, Peidong

2008-02-17

365

Global Changes in DNA Methylation in Seeds and Seedlings of Pyrus communis after Seed Desiccation and Storage  

PubMed Central

The effects of storage and deep desiccation on structural changes of DNA in orthodox seeds are poorly characterized. In this study we analyzed the 5-methylcytosine (m5C) global content of DNA isolated from seeds of common pear (Pyrus communis L.) that had been subjected to extreme desiccation, and the seedlings derived from these seeds. Germination and seedling emergence tests were applied to determine seed viability after their desiccation. In parallel, analysis of the global content of m5C in dried seeds and DNA of seedlings obtained from such seeds was performed with a 2D TLC method. Desiccation of fresh seeds to 5.3% moisture content (mc) resulted in a slight reduction of DNA methylation, whereas severe desiccation down to 2–3% mc increased DNA methylation. Strong desiccation of seeds resulted in the subsequent generation of seedlings of shorter height. A 1-year period of seed storage induced a significant increase in the level of DNA methylation in seeds. It is possible that alterations in the m5C content of DNA in strongly desiccated pear seeds reflect a reaction of desiccation-tolerant (orthodox) seeds to severe desiccation. Epigenetic changes were observed not only in severely desiccated seeds but also in 3-month old seedlings obtained from these seeds. With regard to seed storage practices, epigenetic assessment could be used by gene banks for early detection of structural changes in the DNA of stored seeds.

Michalak, Marcin; Barciszewska, Miroslawa Z.; Barciszewski, Jan; Plitta, Beata P.; Chmielarz, Pawel

2013-01-01

366

Seed storage at elevated partial pressure of oxygen, a fast method for analysing seed ageing under dry conditions (Online First)  

Microsoft Academic Search

Background and Aims Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. Methods Dry

S. P. C. Groot; A. A. Surki; Vos de R. C. H; J. Kodde

2012-01-01

367

?? ????????????? ?????? ???????????????????????????? ?????????????????????????? Number of Seeds in a Fruit, Germination and Effect of Desiccation on Seed Storage in Amoora polystachya ?????? ?????????1  

Microsoft Academic Search

The study on relationship between number of seeds in a fruit and germination and the effect of desiccation on seed storage of Amoora polystachya was conducted at the Silviculture Research Centre 5, Kamphaeng Phet province during March 1998 to July 1999 using seed samples from Kamphaeng Phet and Tak. The study concentrated on effect of number of seed in a

Bundit Ponoy; Prapai Khaennak; Sompong Paktoop

368

Chimpanzee (Pan troglodytes) Seed Dispersal in an Afromontane Forest: Microhabitat Influences on the Postdispersal Fate of Large Seeds1  

Microsoft Academic Search

We examined the postdispersal fate of large seeds (?5 mm) dispersed by chimpanzees in an afromontane forest to evaluate aspects of the effectiveness of seed dispersal by chimpanzees, Pan troglodytes. We assessed the influence of six microhabitat characteristics on seed persistence and germination in seeds dispersed in chimpanzee feces and \\

Nicole Gross-Camp; Beth A. Kaplin

2005-01-01

369

The influence of temperature, light, salinity and seed pre-treatment on the germination of Sesbania sesban seeds  

Microsoft Academic Search

The germination of Sesbania sesban seeds was studied under controlled environmental conditions. Interactive effects of temperature and light, effects of salinity and effects of different pre-treatments of seeds were studied. Sesbania seeds were placed in Petri dishes with filtration paper and the germination and radical development followed during seven day periods. The seeds generally germinated within one or two days.

Truong Hoang Dan; Hans Brix

370

Some Physical Properties of Sesame Seed  

Microsoft Academic Search

In order to design equipment for improved processing of sesame seed (Sesamum indicum L.), some of the physical properties were determined at moisture content of 3·4%w.b. The average dimensions of sesame seed viz., length, width and thickness were 2·80, 1·69 and 0·82mm, respectively. The average geometric mean diameter, sphericity, surface area and density were 1·56mm, 0·56, 7·80mm2 and 1224kgm?3. The

T. Y. Tunde-Akintunde; B. O. Akintunde

2004-01-01

371

Role of Abscisic Acid in Seed Dormancy  

Microsoft Academic Search

Seed dormancy is an adaptive trait that improves survival of the next generation by optimizing the distribution of germination\\u000a over time. The agricultural and forest industries rely on seeds that exhibit high rates of germination and vigorous, synchronous\\u000a growth after germination; hence dormancy is sometimes considered an undesirable trait. The forest industry encounters problems\\u000a with the pronounced dormancy of some

Allison R. Kermode

2005-01-01

372

Hormone Cross-Talk in Seed Dormancy  

Microsoft Academic Search

The choice to become dormant versus continuing to grow is observed in a variety of organisms in response to specific developmental\\u000a and environmental signals. In higher plants this is most obvious during both the establishment and breaking of seed dormancy.\\u000a With the advent of molecular genetic analysis, particularly in Arabidopsis, genes involved in the establishment and breaking of seed dormancy

Siobhan M. Brady; Peter McCourt

2003-01-01

373

Calibration procedures for seeds preloaded in cartridges  

SciTech Connect

Radioactive seeds preloaded in sterilized cartridges or needles are commonly obtainable from manufacturers. Under the US regulations for control of radioactive materials, seed users are required to account for all seeds and independently verify their air kerma strength (S{sub K}). As a result, the viability of inspection schemes that rely on measurement of aggregate seeds is of interest. In this paper we consider the conditions (if any) under which cartridge inspection can satisfy regulatory requirements and still provide practical benefit (i.e., time savings) against the regular single-seed assay. The standards for comparison are the recommendations of AAPM TG40, AAPM TG56, and ACR's 'Standard for the Performance of Manually Loaded Brachytherapy Sources'. The practical benefit is judged in comparison to the effort required to apply the 10% assay recommendation of TG40 to seeds in cartridges. Two specific cartridge inspection schemes are considered: (a) measuring the S{sub K} of each cartridge in a batch; (b) measuring a single cartridge sampled at random from the batch. Unlike the 10% assay, which is defined (imperfectly, in our view) without reference to the prevalence of in-calibration seeds, the estimation of the relative merits of cartridge inspection methods must necessarily include such information and, as such, is manufacturer specific. In this paper results are provided for Oncura model 6711 {sup 125}I seeds in shielded and unshielded Mick cartridges. We show that the only practically useful cartridge inspection scheme is the batch scheme applied to unshielded cartridges. The false positive rates associated with the other schemes are such that we expect to open a cartridge (and perform the 10% assay) at least 80% of the time. While anything less than 100% of the time is theoretically an improvement, this neglects the additional effort required to assay the cartridges.

Brame, Ryan S.; Cohen, Gil'ad N.; Zaider, Marco [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10021 (United States)

2006-08-15

374

Genomic regions governing soybean seed nitrogen accumulation  

Microsoft Academic Search

Nitrogen accumulation in the form of seed protein takes place in soybean [Glycine max (L.) Merr.] during the reproductive stages of development. The purpose of this study was to relate genotypic differences\\u000a in seed nitrogen accumulation with genomic regions controlling nitrogen accumulation in soybean during R5, R6, and R7 growth stages. A population of 101 F6?8 recombinant inbred lines (RIL)

D. R. Panthee; V. R. Pantalone; C. E. Sams; A. M. Saxton; D. R. West; W. E. Rayford

2004-01-01

375

Longitudinal Coherence Preservation and Chirp Evolution in a High Gain Laser Seeded Free Electron Laser Amplifier  

SciTech Connect

In this letter we examine the start-up of a high gain free electron laser in which a frequency-chirped coherent seed laser pulse interacts with a relativistic electron beam. A Green function formalism is used to evaluate the initial value problem. We have fully characterized the startup and evolution through the exponential growth regime. We obtain explicit expressions for the pulse duration, bandwidth and chirp of the amplified light and show that the FEL light remains fully longitudinally coherent.

Murphy, J.B.; /BNL, NSLS; Wu, Juhao; /SLAC; Wang, X.J.; Watanabe, T.; /BNL, NSLS

2006-06-07

376

Gravitational stress on germinating Pinus pinea seeds.  

PubMed

In the germination of lipid-rich seeds, the glyoxylate cycle plays a control role in that, bypassing the two decarboxylative steps of the Krebs cycle; it allows the net synthesis of carbohydrates from lipids. The activity of isocitrate lyase, the key enzyme of the glyoxylate cycle, is an indicator of the state of seed germination: stage of germination, growth of embryo, activation and progress of protein synthesis, depletion of lipidic supplies. In order to investigate the effects of gravity on seed germination, we carried out a study on the time pattern of germination of Pinus pinea seeds that were subjected to a hypergravitational stress (1000 g for 64 h at 4 degrees C), either in a dry or in a wet environment, before to be placed in germination plates. During the whole time of germination, we monitored the state of embryo growth and the most representative enzymes of the main metabolic pathways. In treated wet seeds, we observed an average germination of only 20% with a slowdown of the enzyme activities assayed and a noticeable degradation of lipidic reserves with respect to the controls. These differences in germination are not found for dry seeds. PMID:14558475

Ranaldi, Francesco; Giachetti, Eugenio; Guerin, Elizabeth; Bacci, Stefano; Paoletti, Elena; Boddi, Vieri; Vanni, Paolo

2003-06-01

377

Oxidative Processes in Soybean and Pea Seeds  

PubMed Central

Oxidative processes are probable determinants of longevity of seeds in storage. Measurements of actual oxygen uptake rates were made for soybean and pea seeds as a comparison of short and long lived seeds when light, temperature, and moisture contents were varied. In both peas and soybeans, the oxygen uptake was depressed at low temperatures (<16°C) and low water contents (<0.25 gram H2O per gram dry weight). Apparent activation energies under these conditions are very high, while apparent activation energies of seeds at higher water contents and at temperatures greater than 22°C are much less. Light enhances the level of oxygen uptake in pea, but reduces the level of oxygen uptake in soybean. The complexities of the interactions of oxygen uptake with environmental conditions in soybean compared to pea suggest that oxidative processes occur in soybean at low water contents, but are essentially absent in pea. It is suggested that the additional oxidative processes in soybean with moisture contents between 0.10 and 0.24 gram per gram may contribute to the poorer longevity of soybean seed compared to pea seed.

Vertucci, Christina W.; Leopold, A. Carl

1987-01-01

378

A chirp-compensated, injection-seeded alexandrite laser  

NASA Astrophysics Data System (ADS)

A Q-switched alexandrite laser suitable for high-resolution spectroscopy is described which produces pulses of 35 mJ energy in a 10 MHz bandwidth, with a high-purity TEM00 mode. The laser can be synchronised to external event to within 100 ns. The output pulse length is 120 ns and the repetition rate 25 Hz. The laser is injection-seeded by a Ti:sapphire laser operating around 730 nm. To preserve single-mode seeding under external triggering conditions, and to obtain small time-jitter, active cavity length control was used. In order to achieve the 10 MHz output bandwidth, intra-cavity electro-optic modulators were used to compensate for the frequency chirp. The refractive index of alexandrite was found to vary linearly with inversion density with a constant of proportionality equal to 1.6×10-24 cm3. In pulsed operation at 730 nm, the index change due to this effect is only partially compensated by changes due to ground state phonon relaxation.

Bakule, P.; Baird, P. E. G.; Boshier, M. G.; Cornish, S. L.; Heller, D. F.; Jungmann, K.; Lane, I. C.; Meyer, V.; Sandars, P. H. G.; Toner, W. T.; Towrie, M.; Walling, J. C.

2000-07-01

379

Photon polarization in electron-seeded pair-creation cascades  

NASA Astrophysics Data System (ADS)

An electromagnetic pair-creation cascade seeded by an electron or a photon in an intense plane wave interacts in a complicated way with the external field. Many simulations neglect the vector nature of photons by including their interaction using unpolarized cross sections. After deriving rates for the tree-level processes of nonlinear Compton scattering and pair creation with an arbitrary linearly polarized photon in a constant crossed field, we present results of numerical simulations that include the photon's vector nature. The simulations of seed electrons in a rotating electric field of optical frequency on the one hand support the approximation of using unpolarized cross sections for tree-level processes, which predicts the same number of created particles when using polarized cross section to within around 5%. On the other hand, these simulations show that when the polarization of the photon can be influenced by its environment, the asymmetry in the polarization distribution could be used to significantly increase the rates of each process.

King, B.; Elkina, N.; Ruhl, H.

2013-04-01

380

Infrared frequency combs and supercontinua for multiplex high sensitivity spectroscopy  

PubMed Central

An infrared high-brightness light source based on supercontinuum generation through a SF6 photonic crystal fiber seeded by a Cr4+:YAG femtosecond oscillator is developed for high resolution multiplex spectroscopy in the 1.5 ?m region. Moreover, a multiplex high resolution approach based on a Cr4+:YAG frequency comb enables to probe large spectral domains, with simultaneous sensitive measurement of the absorption and the dispersion associated with all individual spectral features.

Mandon, J.; Sorokin, E.; Sorokina, I.T; Guelachvili, G.; Picque, N.

2010-01-01

381

Variation in seed and germination characteristics among Juniperus procera populations in Ethiopia  

Microsoft Academic Search

Variations in seed and germination characteristics among nine Juniperus procera populations in Ethiopia were evaluated. Bulk seed samples were collected and examined for variations in number of seeds per cone, seed length, width, 1000-seed weight and germination in the laboratory and nursery. In the laboratory, the effect of light conditions on seed germination was tested by incubating the seeds under

Negash Mamo; Mebrate Mihretu; Miftah Fekadu; Mulualem Tigabu; Demel Teketay

2006-01-01

382

Frequency-guided windowed Fourier ridges technique for automatic demodulation of a single closed fringe pattern  

SciTech Connect

A frequency-guided windowed Fourier ridges (FG-WFR) technique for phase extraction from a single closed fringe pattern is proposed. The algorithm begins with a selected seed point and is then guided by the local frequency of the computed pixels. For the seed point, the whole spectral range is examined with WFR to provide reliable local frequency and phase estimation. However, for the rest of the pixels, the WFR algorithm is performed in a more narrow spectral range centered at the determined frequency of its computed neighboring pixel, which not only enforces the continuity of the local frequency between adjacent pixels but also reduces computation consumption significantly. Besides, since phase unwrapping can be readily implemented after demodulation of each pixel, the algorithm directly offers a continuous phase map. The proposed FG-WFR algorithm is verified by successfully demodulating two computer simulated fringe patterns and one noisy experimental fringe pattern.

Li Kai; Pan Bing

2010-01-01

383

Comparison Between High and Low Source Activity Seeds for I-125 Permanent Seed Prostate Brachytherapy  

SciTech Connect

Purpose: To compare low (mean 0.44, SD {+-} 0.0163 mCi) with high source activity (0.61 {+-} 0.0178 mCi) in I{sup 125} permanent seed brachytherapy regarding seed loss, dosimetric outcome, and toxicity. Methods and Materials: The study included 199 patients with prostate cancer treated by permanent seed brachytherapy alone: the first 105 with seeds of lower activity (first cohort), the following 94 with higher seed activity (second cohort). The V100, V150, V200, and D90 were analyzed on the CT scan 30 days after implantation (CTD30). The V100, V150, and D2 of the rectum were also calculated on CTD30. Seed loss was determined 30 days after implantation. Urinary toxicity was measured with the International Prostate Symptom Score (IPSS) questionnaire. Results: Lower seed activity was associated with lower V150 and V200 (p = 0.01 and p {<=} 0.001, respectively) on CTD30. More patients had a V100 <90% and D90 <140 Gy in the lower activity cohort (p = 0.098 for D90 and p = 0.029 for V100) on CTD30. There was no difference between cohorts in dose to the rectum (p = 0.325-0.516) or difference in patients' IPSS score from baseline (p = 0.0.117-0.618), although there was a trend toward more urinary toxicity at 4 and 8 months for high activity seeds. Seed loss as a percentage of implanted seeds was not different (p = 0.324). Conclusions: Higher seed activity (I{sup 125} {>=} 0.6 mCi) results in at least equal V100 and D90 on CTD30. However, dose inhomogeneity and a trend toward more urinary toxicity at 4 and 8 months after treatment may lead to a higher long-term urinary complications.

Masucci, Giuseppina Laura; Donath, David; Tetreault-Laflamme, Audrey; Carrier, Jean-Francois; Hervieux, Yannick; Larouche, Renee Xaviere; Bahary, Jean-Paul [Department of Radiation Oncology Centre Hospitalier de l'Universite de Montreal, Montreal (Canada); Taussky, Daniel, E-mail: daniel.taussky.chum@ssss.gouv.qc.c [Department of Radiation Oncology Centre Hospitalier de l'Universite de Montreal, Montreal (Canada)

2010-11-01

384

Seasonal Variation in Seed Dispersal by Tamarins Alters Seed Rain in a Secondary Rain Forest  

PubMed Central

Reduced dispersal of large seeds into degraded areas is one of the major factors limiting rain forest regeneration, as many seed dispersers capable of transporting large seeds avoid these sites with a limited forest cover. However, the small size of tamarins allows them to use small trees, and hence to disperse seeds into young secondary forests. Seasonal variations in diet and home range use might modify their contribution to forest regeneration through an impact on the seed rain. For a 2-yr period, we followed a mixed-species group of tamarins in Peru to determine how their role as seed dispersers in a 9-yr-old secondary-growth forest varied across seasons. These tamarins dispersed small to large seeds of 166 tree species, 63 of which were into a degraded area. Tamarins’ efficiency in dispersing seeds from primary to secondary forest varied across seasons. During the late wet season, high dietary diversity and long forays in secondary forest allowed them to disperse large seeds involved in later stages of regeneration. This occurred precisely when tamarins spent a more equal amount of time eating a high diversity of fruit species in primary forest and pioneer species in secondary forest. We hypothesized that well-balanced fruit availability induced the movement of seed dispersers between these 2 habitats. The noteworthy number of large-seeded plant species dispersed by such small primates suggests that tamarins play an important, but previously neglected, role in the regeneration and maintenance of forest structure. Electronic supplementary material The online version of this article (doi:10.1007/s10764-010-9413-7) contains supplementary material, which is available to authorized users.

Munoz Lazo, Fernando Julio Joao; Huynen, Marie-Claude; Poncin, Pascal; Heymann, Eckhard W.

2010-01-01

385

Effects of seed traits on the success of direct seeding for restoring southern Thailand’s lowland evergreen forest ecosystem  

Microsoft Academic Search

The success of direct seeding, as a low-cost approach to forest restoration, varies with tree species and seed characteristics.\\u000a A system to predict which tree species are likely to be suitable for direct seeding would therefore be useful for improving\\u000a forest restoration projects. Therefore, this study aimed to determine the effects of seed traits on the success of direct\\u000a seeding

Panitnard Tunjai; Stephen Elliott

386

Identification of QTLs for maize seed vigor at three stages of seed maturity using a RIL population  

Microsoft Academic Search

In maize hybrid seed production, some hybrid seed in the field must be harvested before reaching physiological maturity because\\u000a of the potential damage from early fall frosts. However, early harvesting can result in poor quality and low vigor of seeds.\\u000a To elucidate the genetic basis of seed vigor at different stages of maturity, the seeds of a set of recombinant

Liu Jing-baoFu; Fu Zhi-yuan; Xie Hui-ling; Hu Yan-min; Liu Zong-hua; Duan Liu-jing; Xu Shang-zhong; Tang Ji-hua

2011-01-01

387

Precision Frequency Synthesizing Sources with Excellent Time/Frequency Performances.  

National Technical Information Service (NTIS)

Precision frequency synthesizing sources are needed in the time / frequency measuring system, atomic frequency standards, telemetry, communication, and radar systems. This kind of frequency synthesizing source possesses high frequency accuracy and excelle...

L. Zhou H. Lin

1994-01-01

388

Edge Plasma Effects in DIII-D Impurity Seeded Discharges  

SciTech Connect

DIII-D, ELMing H-mode radiating mantle discharges have been obtained with electron density near the Greenwald density limit and a large fraction of the input power radiated inside the last closed flux surface, significantly reducing peak divertor heat fluxes. In these ''puff and pump'' discharges, the introduction of argon reduces particle flux to divertor tiles by a factor of 4 while peak heat flux is half of the no impurity value, suggesting that impurity seeding may be a useful control tool to reduce wall heat and particle fluxes in fusion reactors. A robust H-mode transport barrier is maintained and there is little change in the ELM energy or in the ELM frequency.

Jackson, G.L.; Boedo, J.A.; Lasnier, C. J.; Leonard, A.W.; McKee, G. R.; Murakami, M; Wade, M.R.; Watkins, J.G.; West, W.P.; Whyte, D.G.

2002-06-01

389

Anharmonic Frequency Analysis.  

National Technical Information Service (NTIS)

A new numerical method of frequency analysis is described, designed mainly to search for discrete frequencies in a time series. An integral transform is applied twice to the data for different reference times. A complex amplitude within a selected narrow ...

A. K. Paul

1971-01-01

390

High Frequency Via.  

National Technical Information Service (NTIS)

Techniques that enable the transitioning of high frequency signals on a printed wiring board processed in accordance with industry standards (such as the IPC specifications) are disclosed. One embodiment provides a high frequency via structure for a print...

J. S. Greeley

2004-01-01

391

Quantum frequency conversion  

Microsoft Academic Search

An experimental scheme is proposed by which the quantum states of two light beams of different frequencies can be interchanged. With this scheme it is possible to generate frequency-tunable squeezed light for spectroscopic applications.

Prem Kumar

1990-01-01

392

Agrobacterium tumefaciens-mediated genetic transformation of Salix matsudana Koidz. using mature seeds.  

PubMed

An Agrobacterium tumefaciens-mediated transformation method was developed for Salix matsudana Koidz. using mature seeds as starting material. Multiple shoots were induced directly from embryonic shoot apices of germinating seeds. Although thidiazuron, 6-benzylaminopurine and zeatin induced multiple shoot induction with high frequency, zeatin (4.5 ?M) was more effective for elongation of shoots and roots. The binary vector pCAMBIA1303, which contained neomycin phosphotransferase as a selectable marker gene and ?-glucuronidase as a reporter gene, was used for transformation. Factors affecting transformation efficiency were examined for optimization of the procedure. Up to 35 of 180 seeds regenerated kanamycin-resistant shoots under optimal transformation conditions as follows: seeds were precultured for 4 days, apices of embryonic shoots were removed and infected with A. tumefaciens strain LBA4404 grown to a cell density equivalent (OD600) of 0.6, and then the infected explants were cultivated at 21 °C for 4 days. Storage of seeds at -20 °C for as long as 3 years had no significant effect on the induction of kanamycin-resistant shoots. Using this method, transgenic plants were obtained within ?5 months with a transformation frequency of 7.2%. Analysis by polymerase chain reaction (PCR) showed that 36.4-93.8% of plants from all 13 tested kanamycin-resistant lines were PCR positive. Several 'escapes' were eliminated by a second round of selection. PCR, Southern blot and reverse transcriptase-PCR analyses of selected transgenic individuals 2 years after cutting propagation confirmed the successful generation of stable transformants. Our method, which minimizes the duration of axenic culture, may provide an alternative procedure for transformation of other recalcitrant Salix species. PMID:23771952

Yang, Jingli; Yi, Jaeseon; Yang, Chuanping; Li, Chenghao

2013-06-01

393

Opiate concentrations following the ingestion of poppy seed products – evidence for `the poppy seed defence'  

Microsoft Academic Search

The universally accepted 300 ng\\/ml cut-off limit for opiate assays stated to be mandatory for all drug screening laboratories by the Substance Abuse and Mental Health Services Administration, has been questioned recently due to positive results being obtained following the ingestion of poppy seed containing food products. To establish the plausibility of the `the poppy seed defence' the concentrations of

Claire Meadway; Steve George; Robin Braithwaite

1998-01-01

394

Effects of Seed Predators of Different Body Size on Seed Mortality in Bornean Logged Forest  

PubMed Central

Background The Janzen-Connell hypothesis proposes that seed and seedling enemies play a major role in maintaining high levels of tree diversity in tropical forests. However, human disturbance may alter guilds of seed predators including their body size distribution. These changes have the potential to affect seedling survival in logged forest and may alter forest composition and diversity. Methodology/Principal Findings We manipulated seed density in plots beneath con- and heterospecific adult trees within a logged forest and excluded vertebrate predators of different body sizes using cages. We show that small and large-bodied predators differed in their effect on con- and heterospecific seedling mortality. In combination small and large-bodied predators dramatically decreased both con- and heterospecific seedling survival. In contrast, when larger-bodied predators were excluded small-bodied predators reduced conspecific seed survival leaving seeds coming from the distant tree of a different species. Conclusions/Significance Our results suggest that seed survival is affected differently by vertebrate predators according to their body size. Therefore, changes in the body size structure of the seed predator community in logged forests may change patterns of seed mortality and potentially affect recruitment and community composition.

Hautier, Yann; Saner, Philippe; Philipson, Christopher; Bagchi, Robert; Ong, Robert C.; Hector, Andy

2010-01-01

395

Hydrothermal time analysis of seed dormancy in true (botanical) potato seeds  

Microsoft Academic Search

As seed dormancy is released within a seed population, both the rate and percentage of germina- tion increase progressively with increasing dose of a dormancy-breaking treatment or condition. Popu- lation-based models can account for this behaviour on the basis of shifting response thresholds as dormancy is alleviated. In particular, hydrothermal time analysis of germination sensitivity to water potential (C) and

Kent J. Bradford; Veria Alvarado

2005-01-01

396

Germination in seed species ingested by opossums: implications for seed dispersal and forest conservation  

Microsoft Academic Search

Seed germination in plant species consumed by oposs ums, genus Didelphis , was investigated in southern Brazil, in order to improve knowledge of the strategies of zoo chorous plants in the Neotropics. Seeds were obtain ed from opossum feces. Thirteen of the most frequent specie s in the diet of local opossums were tested for ger mination rates and germination

Nilton Carlos Cáceres; Emygdio Leite de Araújo Monteiro-Filho

2007-01-01

397

Mitoses in thermodormant lettuce seeds with reference to histological location, localized expansion, and seed storage  

Microsoft Academic Search

Seeds from one lot of “New York” lettuce were sown in each of 5 successive years to compare the effect of duration of storage on the capacity for mitosis in thermodormant seeds with the effect of storage on the capacity for germination under conditions favorable for germination. Whereas the capacity for mitosis in absence of germination increased as a function

Donald E. Foard; Alan H. Haber

1966-01-01

398

Drift Seeds And Drift Fruits : Seeds That Ride The Ocean Currents  

NSDL National Science Digital Library

This essay explores seed dispersal by water and describes some of the physical adaptations that evolution has produced in the seeds and fruits that travel this way. There is a background essay, discussion questions, state and national standards, and links to related Teacher's Domain resources.

2007-01-01

399

Feral genetically modified herbicide tolerant oilseed rape from seed import spills: are concerns scientifically justified?  

PubMed

One of the concerns surrounding the import (for food and feed uses or processing) of genetically modified herbicide tolerant (GMHT) oilseed rape is that, through seed spillage, the herbicide tolerance (HT) trait will escape into agricultural or semi-natural habitats, causing environmental or economic problems. Based on these concerns, three EU countries have invoked national safeguard clauses to ban the marketing of specific GMHT oilseed rape events on their territory. However, the scientific basis for the environmental and economic concerns posed by feral GMHT oilseed rape resulting from seed import spills is debatable. While oilseed rape has characteristics such as secondary dormancy and small seed size that enable it to persist and be redistributed in the landscape, the presence of ferals is not in itself an environmental or economic problem. Crucially, feral oilseed rape has not become invasive outside cultivated and ruderal habitats, and HT traits are not likely to result in increased invasiveness. Feral GMHT oilseed rape has the potential to introduce HT traits to volunteer weeds in agricultural fields, but would only be amplified if the herbicides to which HT volunteers are tolerant were used routinely in the field. However, this worst-case scenario is most unlikely, as seed import spills are mostly confined to port areas. Economic concerns revolve around the potential for feral GMHT oilseed rape to contribute to GM admixtures in non-GM crops. Since feral plants derived from cultivation (as distinct from import) occur at too low a frequency to affect the coexistence threshold of 0.9% in the EU, it can be concluded that feral GMHT plants resulting from seed import spills will have little relevance as a potential source of pollen or seed for GM admixture. This paper concludes that feral oilseed rape in Europe should not be routinely managed, and certainly not in semi-natural habitats, as the benefits of such action would not outweigh the negative effects of management. PMID:21526422

Devos, Yann; Hails, Rosemary S; Messéan, Antoine; Perry, Joe N; Squire, Geoffrey R

2012-02-01

400

Activation of gibberellin biosynthesis and response pathways by low temperature during imbibition of Arabidopsis thaliana seeds.  

PubMed

Exposure of imbibed seeds to low temperature (typically 4 degrees C) is widely used to break seed dormancy and to improve the frequency of germination. However, the mechanism by which temperature accelerates germination is largely unknown. Using DNA microarray and gas chromatography-mass spectrometry analyses, we found that a subset of gibberellin (GA) biosynthesis genes were upregulated in response to low temperature, resulting in an increase in the level of bioactive GAs and transcript abundance of GA-inducible genes in imbibed Arabidopsis thaliana seeds. Using a loss-of-function mutant, the cold-inducible GA biosynthesis gene, AtGA3ox1, was shown to play an essential role in mediating the effect of low temperature. Besides temperature, AtGA3ox1 also is positively regulated by active phytochrome and negatively regulated by GA activity. We show that both red light and GA deficiency act in addition to low temperature to elevate the level of AtGA3ox1 transcript, indicating that multiple signals are integrated by the AtGA3ox1 gene to control seed germination. When induced by low temperature, AtGA3ox1 mRNA was detectable by in situ RNA hybridization in an additional set of cell types relative to that in red light-induced seeds. Our results illustrate that the GA biosynthesis and response pathways are activated during seed imbibition at low temperature and suggest that the cellular distribution of bioactive GAs may be altered under different light and temperature conditions. PMID:14729916

Yamauchi, Yukika; Ogawa, Mikihiro; Kuwahara, Ayuko; Hanada, Atsushi; Kamiya, Yuji; Yamaguchi, Shinjiro

2004-02-01

401

Limit of Frequency Estimation.  

National Technical Information Service (NTIS)

In phase and frequency measurements, the measured phase and frequency are not the true phase and frequency but the ones which are disturbed by noises, due to the effects of the noise processes. In this paper, we discussed the effects of three noise proces...

W. Guo

1992-01-01

402

Genomic Data and Annotation from the SEED  

DOE Data Explorer

The SEED Project is a cooperative effort to annotate ever-expanding genomic data so researchers can conduct effective comparative analyses of genomes. Launched in 2003 by the Fellowship for Interpretation of Genomes (FIG), the project is one of several initiatives in ongoing development of data curation systems. SEED is designed to be used by scientists from numerous centers and with varied research objectives. As such, several institutions have since joined FIG in a consortium, including the University of Chicago, DOE’s Argonne National Laboratory (ANL), the University of Illinois at Urbana-Champaign, and others. As one example, ANL has used SEED to develop the National Microbial Pathogen Data Resource. Other agencies and institutions have used the project to discover genome components and clarify gene functions such as metabolism. SEED also has enabled researchers to conduct comparative analyses of closely related genomes and has supported derivation of stoichiometric models to understand metabolic processes. The SEED Project has been extended to support metagenomic samples and concomitant analytical tools. Moreover, the number of genomes being introduced into SEED is growing very rapidly. Building a framework to support this growth while providing highly accurate annotations is centrally important to SEED. The project’s subsystem-based annotation strategy has become the technological foundation for addressing these challenges.(copied from Appendix 7 of Systems Biology Knowledgebase for a New Era in Biology, A Genomics:GTL Report from the May 2008 Workshop, DOE/SC-0113, Grequrick, S; Fredrickson, J.K.; Stevens, R., Pub March 1, 2009.)

Fonstein, Michael; Kogan, Yakov; Osterman, Andrei; Overbeek, Ross; Vonstein, Veronika The Fellowship for Interpretation of Genomes (FIG)

403

Big sagebrush seed storage. Forest Service research note  

SciTech Connect

Big sagebrush (Artemisia tridentata Nutt.) seeds were stored in three different environments; cool, constant temperature (refrigerator 10 degs. C); room temperature (14 to 24 degs. C); and a nonheated warehouse (-28 to +44 degs. C). In all three cases, humidity was held constant and equal. Significant drop in seed viability occurred first in the seed stored in the nonheated warehouse, followed by seed stored at room temperatures, and then seed stored at cool temperatures. It appeared from this study and studies by others that humidity control is more important to maintaining seed viability than temperature control. The old adage simply states `store seeds in a cool and dry place` - but first make sure the seeds have been properly dried. Drying sagebrush seed during the cool, wet weather of the harvesting period creates special challenges to the producer.

Welch, B.L.; Briggs, S.F.; Johansen, J.H.

1996-12-01

404

Methods and systems for seed planting management and control  

DOEpatents

A seed planting system providing optimal seed spacing in an agricultural field. The seed planting system includes a mobile seed planter having one or more planting shoes, or members being adapted for towing by a farm vehicle or being self-propelled. Sensors, disposed proximate to respective planting shoes, detect seed planting events and send corresponding signals to a computer. Contemporaneously, a geospatial locator acquires, and transmits to the computer, the geospatial location of each planted seed. The computer correlates the geospatial location data with the seed deposition data and generates a seed distribution profile indicating the location of each seed planted in a zone of interest to enable the control of speed spacing.

Svoboda, John M. (Idaho Falls, ID); Hess, J. Richard (Idaho Falls, ID); Hoskinson, Reed L. (Rigby, ID); Harker, David J. (Idaho Falls, ID)

2002-01-01

405

Continued results of the seeds in space experiment  

NASA Technical Reports Server (NTRS)

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 seed were housed on the Space Exposed Experiment Developed for Students (SEEDS) tray in the sealed canister number 6 and in two small vented canisters. The tray was in the F-2 position. The seed were germinated and the germination rates and the development of the resulting plants were compared to the performance of the control seed that stayed in Park Seed's seed storage facility. The initial results were presented in a paper at the First LDEF Post-Retrieval Symposium. There was a better survival rate of the seed in the sealed canister in space than in the storage facility at Park Seed. At least some of the seed in each of the vented canisters survived the exposure to vacuum for almost six years. The number of observed apparent mutations was very low. In the initial testing, the small seeded crops were not grown to maturity to check for mutations and obtain second generation seed. These small seeded crops have now been grown for evaluation and second generation seed collected.

Alston, Jim A.

1993-01-01

406

Frequency selective infrared sensors  

DOEpatents

A frequency selective infrared (IR) photodetector having a predetermined frequency band. The exemplary frequency selective photodetector includes: a dielectric IR absorber having a first surface and a second surface substantially parallel to the first surface; an electrode electrically coupled to the first surface of the dielectric IR absorber; and a frequency selective surface plasmonic (FSSP) structure formed on the second surface of the dielectric IR absorber. The FSSP structure is designed to selectively transmit radiation in the predetermined frequency band that is incident on the FSSP structure substantially independent of the angle of incidence of the incident radiation on the FSSP structure.

Davids, Paul; Peters, David W

2013-05-28

407

Laser phase errors in seeded free electron lasers  

NASA Astrophysics Data System (ADS)

Harmonic seeding of free electron lasers has attracted significant attention as a method for producing 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 and impede production of transform-limited pulses. 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.

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

2012-03-01

408

Laser Phase Errors in Seeded Free Electron Lasers  

SciTech Connect

Harmonic seeding of free electron lasers has attracted significant attention as a method for producing 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 and impede production of transform-limited pulses. 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.

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

2012-04-17

409

Device for isolation of seed crystals during processing of solution  

DOEpatents

A device for isolation of see crystals during processing of solutions. The device enables a seed crystal to be introduced into the solution without exposing the solution to contaminants or to sources of drying and cooling. The device constitutes a seed protector which allows the seed to be present in the growth solution during filtration and overheating operations while at the same time preventing the seed from being dissolved by the under saturated solution. When the solution processing has been completed and the solution cooled to near the saturation point, the seed protector is opened, exposing the seed to the solution and allowing growth to begin.

Montgomery, Kenneth E. (Tracy, CA); Zaitseva, Natalia P. (Livermore, CA); Deyoreo, James J. (Livermore, CA); Vital, Russell L. (Tracy, CA)

1999-01-01

410

Germination response of MR 219 rice variety to different exposure times and periods of 2450 MHz microwave frequency.  

PubMed

Germination is a key process in plants' phenological cycles. Accelerating this process could lead to improvment of the seedling growth as well as the cultivation efficiency. To achieve this, the effect of microwave frequency on the germination of rice seeds was examined. The physiological feedbacks of the MR 219 rice variety in terms of seed germination rate (GR), germination percentage (GP), and mean germination time (MGT) were analyzed by exposing its seeds to 2450 MHz of microwave frequency for one, four, seven, and ten hours. It was revealed that exposing the seeds to the microwave frequency for 10 hours resulted in the highest GP. This treatment led to 100% of germination after three days with a mean germination time of 2.1 days. Although the other exposure times of microwave frequency caused the moderate effects on germination with a GP(a3) ranged from 93% to 98%, they failed to reduce the MGT(a3). The results showed that ten-hour exposure times of microwave frequency for six days significantly facilitated and improved the germination indices (primary shoot and root length). Therefore, the technique is expected to benefit the improvement of rice seed germination considering its simplicity and efficacy in increasing the germination percentage and rate as well as the primary shoot and root length without causing any environmental toxicity. PMID:24307869

Talei, Daryush; Valdiani, Alireza; Maziah, Mahmood; Mohsenkhah, Mohammad

2013-01-01

411

The qSD12 Locus Controls Offspring Tissue-Imposed Seed Dormancy in Rice  

PubMed Central

Seed component structures were grouped into maternal and offspring (embryo and endosperm) tissues to characterize a dormancy quantitative trait locus (QTL) for tissue-specific function using a marker-assisted genetic approach. The approach was devised to test if genotypic/allelic frequencies of a marker tightly linked to the QTL deviate from Mendelian expectations in germinated and nongerminated subpopulations derived from a segregation population of partially after-ripened seeds and was applied to the dormancy QTL qSD12 and qSD7-1 in a nearly isogenic background of rice. Experimental results unambiguously demonstrated that qSD12 functions in the offspring tissue(s) and suggested that qSD7-1 may control dormancy through the maternal tissues. These experiments also provide the first solid evidence that an offspring tissue-imposed dormancy gene contributes to the segregation distortion in a mapping population developed from partially after-ripened seeds and, in part, to the germination heterogeneity of seeds from hybrid plants. Offspring and maternal tissue-imposed dormancy genes express in very early and late stages of the life cycle, respectively, and interact to provide the species with complementary adaptation strategies. The qSD12 locus was narrowed to the region of ?600 kbp on a high-resolution map to facilitate cloning and marker-assisted selection of the major dormancy gene.

Gu, Xing-You; Turnipseed, E. Brent; Foley, Michael E.

2008-01-01

412

Stimulated Brillouin scattering suppression with a chirped laser seed: comparison of dynamical model to experimental data  

NASA Astrophysics Data System (ADS)

When scaling CW single-mode fiber amplifiers to high power, the first nonlinear limitation that appears for narrowlinewidth seed lasers is stimulated Brillouin scattering (SBS). We present a dynamical simulation of Brillouin scattering in a Yb-doped fiber amplifier that numerically solves the differential equations in z and t describing the laser, Stokes and pump waves, the inversion, and the density fluctuations that seed the scattering process. We compare the model to experimental data, and show that a linearly chirped seed laser is an efficient form of SBS suppression; especially for long delivery fibers. The frequency chirp decreases the interaction length by chirping through the Brillouin resonance in a time that is short compared to the fiber transit time. The seed has a highly linear chirp of 1014 - 1016 Hz/s at 1064 nm which preserves a well-defined phase relationship in time. This method of SBS suppression retains a long effective coherence length for purposes of coherent combining, while at high chirps appears to the SBS as a large linewidth, increasing the threshold. An increase in fiber length increases the laser bandwidth as seen by the SBS, leading to a fiberlength- independent SBS threshold.

Petersen, Eliot; Yang, Zhi; White, Jeffrey O.; Rakuljic, George; Satyan, Naresh; Vasilyev, Arseny; Yariv, Amnon

2014-03-01

413

Efficient injection-seeded kHz picosecond LBO optical parametric generator  

NASA Astrophysics Data System (ADS)

We report a highly efficient optical parametric generator (OPG) in lithium triborate (LBO). A frequency-doubled passively mode-locked diode-pumped Nd:YVO4 oscillator amplifier (MOPA) system is used as the pump radiation source. Focussing according to the theory of Boyd and Kleinman leads to a pump power density of 50 GW/cm2, which is well below the damage threshold of LBO of 80 GW/cm2. The overall conversion efficiency reaches a value of 72% measured at degeneracy. The tuning range of the OPG ranges from 760 nm (signal) to 1770 nm (idler) when referring to an overall conversion efficiency of 50%. The beam quality is excellent for conversion efficiencies below 40% ( M 2<1.3). The typically 10 nm (RMS) broad spectrum can be narrowed by injection seeding the OPG. Injection seeding is demonstrated for a signal wavelength of 922.54 nm. A seed cw power of 30 nW is sufficient to reduce the spectral width to 0.1 nm (RMS). The measured injection-seeded OPG pulse duration is 9 ps (FWHM). This results in a time-bandwidth product of 1.30, which is 4.1 times the theoretical limit of 0.315 for sech2-shaped pulses.

Traub, T.; Ruebel, F.; L'Huillier, J. A.

2011-01-01

414

Myrmecochory by small ants - Beneficial effects through elaiosome nutrition and seed dispersal  

NASA Astrophysics Data System (ADS)

Seed dispersal by ants (myrmecochory) is a common mutualism in temperate woodlands of the Northern hemisphere. In this paper we highlight the contribution of one of the most abundant ant species of Eastern Central Europe, Temnothorax crassispinus, to myrmecochory. In field and mesocosm studies we found that T. crassispinus workers disperse seeds over distances of up to 162 cm and carry them to their nests, thereby enabling the spread of Chelidonium majus seedlings. In a controlled feeding experiment with four different feeding regimes, we supplemented the respective diet of a fraction of the nests with the elaiosome-bearing seeds of C. majus and Scilla bifolia. Here, ant workers carried seeds to their nest and fed elaiosome pieces to their larvae. Subsequent production of sexual offspring and dry weights of sexual pupae were positively correlated with increasing feeding frequencies. With supplementary elaiosome feeding, the female dry weight was significantly higher, whereas the male dry weight decreased. Our results indicate a nutritional benefit from elaiosomes to the ants, which may cause shifts of investment, and at the same time underline the ecological relevance of Temnothorax ants for elaiosome-bearing plants.

Fokuhl, Gerriet; Heinze, Jürgen; Poschlod, Peter

2012-01-01

415

Radio frequency detection assembly and method for detecting radio frequencies  

DOEpatents

A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

Cown, Steven H. (Rigby, ID); Derr, Kurt Warren (Idaho Falls, ID)

2010-03-16

416

Seed dormancy and germination--emerging mechanisms and new hypotheses  

PubMed Central

Seed dormancy has played a significant role in adaptation and evolution of seed plants. While its biological significance is clear, molecular mechanisms underlying seed dormancy induction, maintenance and alleviation still remain elusive. Intensive efforts have been made to investigate gibberellin and abscisic acid metabolism in seeds, which greatly contributed to the current understanding of seed dormancy mechanisms. Other mechanisms, which might be independent of hormones, or specific to the seed dormancy pathway, are also emerging from genetic analysis of “seed dormancy mutants.” These studies suggest that chromatin remodeling through histone ubiquitination, methylation and acetylation, which could lead to transcription elongation or gene silencing, may play a significant role in seed dormancy regulation. Small interfering RNA and/or long non-coding RNA might be a trigger of epigenetic changes at the seed dormancy or germination loci, such as DELAY OF GERMINATION1. While new mechanisms are emerging from genetic studies of seed dormancy, novel hypotheses are also generated from seed germination studies with high throughput gene expression analysis. Recent studies on tissue-specific gene expression in tomato and Arabidopsis seeds, which suggested possible “mechanosensing” in the regulatory mechanisms, advanced our understanding of embryo-endosperm interaction and have potential to re-draw the traditional hypotheses or integrate them into a comprehensive scheme. The progress in basic seed science will enable knowledge translation, another frontier of research to be expanded for food and fuel production.

Nonogaki, Hiroyuki

2014-01-01

417

Assessing potential exposure of birds to pesticide-treated seeds.  

PubMed

Seed treatments are widely used for crop protection and present a particular risk to granivorous birds. UK risk assessment for seed treatments has tended to focus on highly granivorous species; however, under some conditions, non-granivorous birds will take seeds. Better data is needed on which species eat seeds for which pesticide treatments are used. To identify which species will take and eat a range of crop seeds in common usage in the UK, birds visiting bait stations at which untreated seed was presented were video recorded. Information was also obtained on how much seed is taken by individual birds. The seeds tested were wheat, barley, maize, oilseed rape, grass, peas and pelleted sugar beet. For many of the species observed at the bait stations, the amounts of seed consumed during single visits were sufficient to pose a potential risk (toxicity-exposure ratio < 10) if the seed had been treated with one of the more acutely toxic seed treatments. Previous studies have shown that de-husking of seeds can substantially reduce birds' exposure. This paper provides information on which of the species recorded de-husked which seeds, in field conditions. The use of these data in pesticide risk assessment is considered. PMID:16151611

Prosser, Phil; Hart, A D M

2005-10-01

418

Biochemical pathways in seed oil synthesis.  

PubMed

Oil produced in plant seeds is utilized as a major source of calories for human nutrition, as feedstocks for non-food uses such as soaps and polymers, and can serve as a high-energy biofuel. The biochemical pathways leading to oil (triacylglycerol) synthesis in seeds involve multiple subcellular organelles, requiring extensive lipid trafficking. Phosphatidylcholine plays a central role in these pathways as a substrate for acyl modifications and likely as a carrier for the trafficking of acyl groups between organelles and membrane subdomains. Although much has been clarified regarding the enzymes and pathways responsible for acyl-group flux, there are still major gaps in our understanding. These include the identity of several key enzymes, how flux between alternative pathways is controlled and the specialized cell biology leading to biogenesis of oil bodies that store up to 80% of carbon in seeds. PMID:23529069

Bates, Philip D; Stymne, Sten; Ohlrogge, John

2013-06-01

419

Seeded hot dark matter models with inflation  

NASA Technical Reports Server (NTRS)

We examine massive neutrino (hot dark matter) models for large-scale structure in which the density perturbations are produced by randomly distributed relic seeds and by inflation. Power spectra, streaming velocities, and the Sachs-Wolfe quadrupole fluctuation are derived for this model. We find that the pure seeded hot dark matter model without inflation produces Sachs-Wolfe fluctuations far smaller than those seen by COBE. With the addition of inflationary perturbations, fluctuations consistent with COBE can be produced. The COBE results set the normalization of the inflationary component, which determines the large-scale (about 50/h Mpc) streaming velocities. The normalization of the seed power spectrum is a free parameter, which can be adjusted to obtain the desired fluctuations on small scales. The power spectra produced are very similar to those seen in mixed hot and cold dark matter models.

Gratsias, John; Scherrer, Robert J.; Steigman, Gary; Villumsen, Jens V.

1993-01-01

420

Signposts of Planets Observed by SEEDS  

NASA Technical Reports Server (NTRS)

The Strategic Exploration of Exoplanets and Disks at Subaru (SEEDS) is the first strategic observing program (SSOPs) awarded by the National Astronomical Observatory of Japan (NAOJ). SEEDS targets a broad sample of stars that span a wide range of masses and ages to explore the formation and evolution of planetary systems. This survey has been awarded 120 nights over five years time to observe nearly 500 stars. Currently in the second year, SEEDS has already produced exciting new results for the protoplanetary disk AB AUf, transitional disk LkCa15, and nearby companion to GJ 758. We present the survey architecture, performance, recent results, and the projected sample. Finally, we will discuss planned upgrades to the high contrast instrumentation at the Subaru

McElwain, Michael

2011-01-01

421

Subaru SEEDS Survey of Exoplanets and Disks  

NASA Technical Reports Server (NTRS)

The Strategic Exploration of Exoplanets and Disks at Subaru (SEEDS) is the first strategic observing program (SSOPs) awarded by the National Astronomical Observatory of Japan (NAOJ). SEEDS targets a broad sample of stars that span a wide range of masses and ages to explore the formation and evolution of planetary systems. This survey has been awarded 120 nights over five years time to observe nearly 500 stars. Currently in the second year, SEEDS has already produced exciting new results for the protoplanetary disk AB Aur, transitional disk LkCa15, and nearby companion to GJ 758. We present the survey architecture, performance, recent results, and the projected sample. Finally, we will discuss planned upgrades to the high contrast instrumentation at the Subaru Telescope

McElwain, Michael W.

2012-01-01

422

Indirectly seeded optical parametric generation in PPLN  

NASA Astrophysics Data System (ADS)

We show that pulsed quasi-phase matched optical parametric generation can be indirectly seeded with a weak cw beam with a wavelength different from that of either the signal or the idler waves. This is accomplished by first mixing the cw seed beam with the pulsed pump beam in a periodically poled lithuim niobate (PPLN) crystal to produce a weak signal beam which is then further amplified in the same crystal. The crystal has two regions with different domain structure periodicities. In the first region the periodicity is chosen to create a beam at 1561.5 nm, resulting from mixing a 15 mW, 632.8 nm beam and an intense, 7 ns 1064 nm pulse. In the second region, the periodicity produces amplification of this signal beam at 1561.5 nm. The output beam inherits the spectral and mode characteristics of the weak seed beam.

Orozco-Arellanes, M. J.; Alonso, F.; Rios, L. A.; Cudney, Roger S.

2003-11-01

423

``From seed-to-seed'' experiment with wheat plants under space-flight conditions  

NASA Astrophysics Data System (ADS)

An important goal with plant experiments in microgravity is to achieve a complete life cycle, the ``seed-to-seed experiment''. Some Soviet attempts to reach this goal are described, notably an experiment with the tiny mustard, Arabidopsis thaliana, in the Phyton 3 device on Salyut 7. Normal seeds were produced although yields were reduced and development was delayed. Several other experiments have shown abnormalities in plants grown in space. In recent work, plants of wheat (Triticum aestivum) were studied on the ground and then in a preliminary experiment in space. Biometric indices of vegetative space plants were 2 to 2.5 times lower than those of controls, levels of chlorophyll a and b were reduced (no change in the ratio of the two pigments), carotenoids were reduced, there was a serious imbalance in major minerals, and membrane lipids were reduced (no obvious change in lipid patterns). Following the preliminary studies, an attempt was made with the Svetoblock-M growth unit to grow a super-dwarf wheat cultivar through a life cycle. The experiment lasted 167 d on Mir. Growth halted from about day 40 to day 100, when new shoots appeared. Three heads had appeared in the boot (surrounded by leaves) when plants were returned to earth. One head was sterile, but 28 seeds matured on earth, and most of these have since produced normal plants and seeds. In principle, a seed-to-seed experiment with wheat should be successful in microgravity.

Mashinsky, A.; Ivanova, I.; Derendyaeva, T.; Nechitailo, G.; Salisbury, F.

1994-11-01

424

The evolution of seed dormancy: environmental cues, evolutionary hubs, and diversification of the seed plants.  

PubMed

Seed dormancy, by controlling the timing of germination, can strongly affect plant survival. The kind of seed dormancy, therefore, can influence both population and species-level processes such as colonization, adaptation, speciation, and extinction. We used a dataset comprising over 14 000 taxa in 318 families across the seed plants to test hypotheses on the evolution of different kinds of seed dormancy and their association with lineage diversification. We found morphophysiological dormancy to be the most likely ancestral state of seed plants, suggesting that physiologically regulated dormancy in response to environmental cues was present at the origin of seed plants. Additionally, we found that physiological dormancy (PD), once disassociated from morphological dormancy, acted as an 'evolutionary hub' from which other dormancy classes evolved, and that it was associated with higher rates of lineage diversification via higher speciation rates. The environmental sensitivity provided by dormancy in general, and by PD in particular, appears to be a key trait in the diversification of seed plants. PMID:24684268

Willis, Charles G; Baskin, Carol C; Baskin, Jerry M; Auld, Josh R; Venable, D Lawrence; Cavender-Bares, Jeannine; Donohue, Kathleen; Rubio de Casas, Rafael

2014-07-01

425

Germination Ecophysiology of Annona crassiflora Seeds  

PubMed Central

Background and Aims Little is known about environmental factors that break morphophysiological dormancy in seeds of the Annonaceae and the mechanisms involved. The aim of this study was to characterize the morphological and physiological components of dormancy of Annona crassiflora, a tree species native to the Cerrado of Brazil, in an ecophysiological context. Methods Morphological and biochemical characteristics of both embryo and endosperm were monitored during dormancy break and germination at field conditions. Seeds were buried in the field and exhumed monthly for 2 years. Germination, embryo length and endosperm digestion, with endo-?-mannanase activity as a marker, were measured in exhumed seeds, and scanning electron microscopy was used to detect cell division. The effect of constant low and high temperatures and exogenous gibberellins on dormancy break and germination was also tested under laboratory conditions. Key Results After burial in April, A. crassiflora seeds lost their physiological dormancy in the winter months with lowest monthly average minimum temperatures (May–August) prior to the first rainfall of the wet season. The loss of physiological dormancy enabled initiation of embryo growth within the seed during the first 2 months of the rainy season (September–October), resulting in a germination peak in November. Embryo growth occurred mainly through cell expansion but some dividing cells were also observed. Endosperm digestion started at the micropylar side around the embryo and diffused to the rest of the endosperm. Exogenous gibberellins induced both embryo growth and endo-?-mannanase activity in dormant seeds. Conclusions The physiological dormancy component is broken by low temperature and/or temperature fluctuations preceding the rainy season. Subsequent embryo growth and digestion of the endosperm are both likely to be controlled by gibberellins synthesized during the breaking of physiological dormancy. Radicle protrusion thus occurred at the beginning of the rainy season, thereby maximizing the opportunity for seedlings to emerge and establish.

da Silva, Edvaldo A. A.; de Melo, Daniel L. B.; Davide, Antonio C.; de Bode, Nienke; Abreu, Guilherme B.; Faria, Jose M. R.; Hilhorst, Henk W. M.

2007-01-01

426

7 CFR 201.76 - Minimum Land, Isolation, Field, and Seed Standards.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Minimum Land, Isolation, Field, and Seed Standards. 201.76 Section 201.76 Agriculture...DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Certified Seed § 201.76...

2009-01-01

427

7 CFR 201.76 - Minimum Land, Isolation, Field, and Seed Standards.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Minimum Land, Isolation, Field, and Seed Standards. 201.76 Section 201.76 Agriculture...DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Certified Seed § 201.76...

2010-01-01

428

Galactomannan: a versatile biodegradable seed polysaccharide.  

PubMed

Polysaccharides have been finding, in the last decades, very interesting and useful applications in the biomedical and, specifically, in the biopharmaceutical field. Galactomannans are a group of storage polysaccharides from various plant seeds that reserve energy for germination in the endosperm. There are four major sources of seed galactomannans: locust bean (Ceratonia siliqua), guar (Cyamopsis tetragonoloba), tara (Caesalpinia spinosa Kuntze), and fenugreek (Trigonella foenum-graecum L.). Through keen references of reported literature on galactomannans, in this review, we have described occurrence of various galactomannans, its physicochemical properties, characterization, applications, and overview of some major galactomannans. PMID:23707734

Prajapati, Vipul D; Jani, Girish K; Moradiya, Naresh G; Randeria, Narayan P; Nagar, Bhanu J; Naikwadi, Nikhil N; Variya, Bhavesh C

2013-09-01

429

New kaurene diterpenoid glycosides from fenugreek seeds.  

PubMed

Two new kaurene diterpenoid glycosides, named Graecumoside A (1) and B (2), were isolated from fenugreek seeds, along with three known flavonoid-C-glycosides, isoorientin (3), isovitexin (4) and vitexin (5). By combined analyses of 1D- and 2D-NMR, and MS spectroscopy, the structures of two new compounds were elucidated as 3-O-?- D-glucopyranosyl kaur-5, 16-dien-3?, 6, 13?-trihydroxy-7-oxo-18-oic acid methyl ester and 3-O-?-neohesperidosyl kaur-5, 16-dien-3?, 6, 13?-trihydroxy-7-oxo-18-oic acid methyl ester, respectively. The kaurene diterpenoid glycosides were first isolated and identified from fenugreek seeds. PMID:22950814

Pang, Xu; Kang, Li-Ping; Yu, He-Shui; Zhao, Yang; Xiong, Cheng-Qi; Zhang, Jie; Ma, Bai-Ping

2013-01-01

430

Needle tract seeding: An avoidable complication.  

PubMed

Needle tract seeding refers to implantation of tumor cells by contamination when instruments like biopsy needles are used to examine, excise or ablate a tumor. Implantation along needle tract may lead to change of stage of the tumor, converting a resectable tumor into an inoperable one. In this paper we have reviewed the cases of needle tract seeding due to fine needle aspiration cytology (FNAC) procedure. We analyzed the various aspects of needle tract seedling and suggested how to take precautionary measures to prevent it. Diagn. Cytopathol. 2014;42:636-640. © 2014 Wiley Periodicals, Inc. PMID:24591300

Tyagi, Ruchita; Dey, Pranab

2014-07-01

431

Frequency conversion system  

NASA Technical Reports Server (NTRS)

A frequency conversion system comprises first and second gain sources providing first and second frequency radiation outputs where the second gain source receives as input the output of the first gain source and, further, the second gain source comprises a Raman or Brillouin gain fiber for wave shifting a portion of the radiation of the first frequency output into second frequency radiation output to provided a combined output of first and second frequencies. Powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Sanders, Steven (Inventor); Waarts, Robert G. (Inventor)

2001-01-01

432

PhysicoChemical Characteristics of Citrus Seeds and Seed Oils from Pakistan  

Microsoft Academic Search

The physico-chemical characteristics of the seeds and seed oils of four citrus species, Mitha (Citrus limetta), Grapefruit (Citrus paradisi), Mussami (Citrus sinensis), and Kinnow (Citrus reticulata) were investigated. The hexane-extracted oil content of citrus seeds ranged from 27.0 to 36.5%. The protein, fiber and ash\\u000a contents were found to be 3.9–9.6%, 5.0–8.5%, and 4.6–5.6%, respectively. The extracted oils exhibited an

Farooq Anwar; Rehana Naseer; M. I. Bhanger; Samia Ashraf; Farah Naz Talpur; Felix Adekunle Aladedunye

2008-01-01

433

Challenges facing seed banks and agriculture in relation to seed quality.  

PubMed

Seeds form a convenient vehicle for storage of germplasm, both for agricultural purposes and conservation of wild species. When required, seeds can be taken from storage and germinated, and plants can be propagated for the desired purpose, e.g., crop production or biome restoration. However, seed dormancy often interferes with stand establishment or industrial utilization in crops and germination of wild species. An anticipated termination of dormancy (i.e., before crop harvest) also occurs, with preharvest sprouting as a consequence. In order to overcome these problems, a better understanding of dormancy is required. This chapter is devoted to discuss the achievement of such understanding in problematic species. PMID:21898247

Rodríguez, M Verónica; Toorop, Peter E; Benech-Arnold, Roberto L

2011-01-01

434

Ubiquitin-mediated control of seed size in plants  

PubMed Central

Seed size in higher plants is an important agronomic trait, and is also crucial for evolutionary fitness. In flowering plants, the seed comprises three major anatomical components, the embryo, the endosperm and the seed coat, each with different genetic compositions. Therefore, seed size is coordinately determined by the growth of the embryo, endosperm and maternal tissue. Recent studies have revealed multiple pathways that influence seed size in plants. Several factors involved in ubiquitin-related activities have been recently known to determine seed size in Arabidopsis and rice. In this review, we summarize current knowledge of ubiquitin-mediated control of seed size and discuss the role of the ubiquitin pathway in seed size control.

Li, Na; Li, Yunhai

2014-01-01

435

Detection of brachytherapy seeds using 3-D transrectal ultrasound.  

PubMed

Detection of brachytherapy seeds plays a key role in dosimetry for prostate brachytherapy. However, seed localization using B-mode transrectal ultrasound (TRUS) still remains a challenge for prostate brachytherapy, mainly due to the small size of brachytherapy seeds in the relatively low-quality B-mode TRUS images. In this paper, we propose a new solution for brachytherapy seed detection using 3-D ultrasound. A 3-D reflected power image is computed from ultrasound RF signals, instead of conventional B-mode images. Then, implanted seeds are segmented in 3-D local search spaces that are determined by a priori knowledge, e.g., needle entry points and seed placements. Needle insertion tracks are also detected locally by the Hough transform. Experimental results show that the proposed solution works well for seed localization in a prostate phantom implanted according to a realistic treatment plan with 136 seeds from 26 needles. PMID:20595088

Wen, Xu; Salcudean, Septimiu Tim E; Lawrence, Peter D

2010-10-01

436

7 CFR 457.108 - Sunflower seed crop insurance provisions.  

Code of Federal Regulations, 2010 CFR

...2) All harvested production from the insurable...Mature sunflower seed production may be adjusted for excess moisture and quality deficiencies. If... (4) Sunflower seed production that is eligible for quality adjustment, as...

2010-01-01

437

Prostate brachytherapy seed migration to the left testicular vein  

Microsoft Academic Search

PurposeProstate brachytherapy seeds may detach from their initial insertion sites and migrate to lungs, heart, coronary artery, liver, kidney, and vertebral venous plexus. The authors present the left testicular vein as additional site of seed embolization.

Ba D. Nguyen; Genevieve L. Egnatios

2010-01-01

438

Top seeded growth and joining of bulk YBCO.  

SciTech Connect

We report (i) systematic studies of the growth rate for melt textured YBCO, (ii) top seeding growth techniques to determine the minimum seed size, and (iii) joining techniques for melt textured YBCO, enabling the fabrication of large single domain structures of arbitrary shape. Seeded growth of YBCO occurs in a narrow temperature window about 20 C below the peritectic decomposition temperature. Successful top seeding depends on the size of the NdBCO seed crystal. Small seeds are eventually dissolved in the melt before nucleation occurs, while large seeds regularly produce single domain monoliths. Joining techniques based on seeding of low melting point Tm123/Y211 filler material by neighboring YBCO are described. Magneto-optical images of the YBCO/TmBCO/YBCO assembly show no detectable penetration of magnetic field at the joints.

Zheng, H.; Veal, B. W.; Paulikas, A.; Nikolova, R.; Welp, U.; Claus, H.; Crabtree, G. W.

1999-10-26

439

Tanzania Seed Industry Survey: Report of Evaluations and Recommendations.  

National Technical Information Service (NTIS)

The production of high quality seeds of improved and adapted crop varieties is essential for economic improvement of Tanzania's agricultural sector. This report presents the findings of a survey of the components of Tanzania's modern seed industry: breede...

A. R. Hagan R. J. Bevins L. E. Cavanah J. M. Poehlamn

1979-01-01

440

Kin conflict in seed development: an interdependent but fractious collective.  

PubMed

Seeds are complex structures that unite diploid maternal tissues with filial tissues that may be haploid (gametophyte), diploid (embryo), or triploid (endosperm). Maternal tissues are predicted to favor smaller seeds than are favored by filial tissues, and filial genes of maternal origin are predicted to favor smaller seeds than are favored by filial genes of paternal origin. Consistent with these predictions, seed size is determined by an interplay between growth of maternal integuments, which limits seed size, and of filial endosperm, which promotes larger seeds. Within endosperm, genes of paternal origin favor delayed cellularization of endosperm and larger seeds, whereas genes of maternal origin favor early cellularization and smaller seeds. The ratio of maternal and paternal gene products in endosperm contributes to the failure of crosses between different ploidy levels of the same species and crosses between species. Maternally expressed small-interfering RNAs (siRNAs) are predicted to associate with growth-enhancing genes. PMID:23641801

Haig, David

2013-01-01

441

String stabilized ribbon growth a method for seeding same  

DOEpatents

This invention is a method of initiating or seeding the growth of a crystalline or polycrystalline ribbon by the String Stabilized Ribbon Growth Method. The method for seeding the crystal growth comprises contacting a melt surface with a seed and two strings used in edge stabilization. The wetted strings attach to the wetted seed as a result of the freezing of the liquid melt. Upon drawing the seed, which is attached to the strings, away from the melt surface a melt liquid meniscus, a seed junction, and a growth interface forms. Further pulling of the attached seed causes a crystal ribbon to grow at the growth interface. The boundaries of the growing ribbon are: at the top the seed junction, at the bottom the freezing boundary of the melt liquid meniscus, and at the edges frozen-in strings.

Sachs, Emanuel M. (39 Harding Ave., Belmont, MA 02178)

1987-08-25

442

Improved resistance to controlled deterioration in transgenic seeds.  

PubMed

We show that seed-specific overexpression of the sunflower (Helianthus annuus) HaHSFA9 heat stress transcription factor (HSF) in tobacco (Nicotiana tabacum) enhances the accumulation of heat shock proteins (HSPs). Among these proteins were HSP101 and a subset of the small HSPs, including proteins that accumulate only during embryogenesis in the absence of thermal stress. Levels of late embryogenesis abundant proteins or seed oligosaccharides, however, were not affected. In the transgenic seeds, a high basal thermotolerance persisted during the early hours of imbibition. Transgenic seeds also showed significantly improved resistance to controlled deterioration in a stable and transgene-dependent manner. Furthermore, overexpression of HaHSFA9 did not have detrimental effects on plant growth or development, including seed morphology and total seed yield. Our results agree with previous work tentatively associating HSP gene expression with phenotypes important for seed longevity. These findings might have implications for improving seed longevity in economically important crops. PMID:16998084

Prieto-Dapena, Pilar; Castaño, Raúl; Almoguera, Concepción; Jordano, Juan

2006-11-01

443

Anti-Cad lectin from the seeds of Leonurus cardiaca.  

PubMed

A predominantly Cad-specific lectin is present in the seeds of Leonurus cardiaca. Extracts of these seeds makes a valuable addition to reagents used in the elucidation of red cell polyagglutinability. PMID:535304

Bird, G W; Wingham, J

1979-01-01

444

Characterization of thiamin-binding protein from buckwheat seeds.  

PubMed

A thiamin-binding protein from buckwheat (Fagopyrum esculentum Moench) seeds gave two bands of 56-and 50-kDa in the absence of 2-mercaptoethanol and a single band of 25-kDa in the presence of 2-mercaptoethanol on sodium dodecylsulfate gel electrophoresis. These results indicate that the protein consists of polypeptides linked by disulfide bond(s). The protein isolated from buckwheat seeds did not have immunological homology with the thiamin-binding proteins from rice seeds and sesame seeds. However, the binding of the protein to thiamin was inhibited by the modification of the carboxyl residues in the protein as well as that of the thiamin-binding protein from rice seeds. These results suggest that the thiamin-binding protein from buckwheat seeds differ from those from rice seeds and sesame seeds as to subunit structure or immunological properties, but resembles them in the mechanism of binding thiamin. PMID:9675712

Watanabe, K; Shimizu, M; Adachi, T; Yoshida, T; Mitsunaga, T

1998-04-01

445

Ecosystem services from keystone species: diversionary seeding and seed-caching desert rodents can enhance Indian ricegrass seedling establishment  

USGS Publications Warehouse

Seeds of Indian ricegrass (Achnatherum hymenoides), a native bunchgrass common to sandy soils on arid western rangelands, are naturally dispersed by seed-caching rodent species, particularly Dipodomys spp. (kangaroo rats). These animals cache large quantities of seeds when mature seeds are available on or beneath plants and recover most of their caches for consumption during the remainder of the year. Unrecovered seeds in caches account for the vast majority of Indian ricegrass seedling recruitment. We applied three different densities of white millet (Panicum miliaceum) seeds as “diversionary foods” to plots at three Great Basin study sites in an attempt to reduce rodents' over-winter cache recovery so that more Indian ricegrass seeds would remain in soil seedbanks and potentially establish new seedlings. One year after diversionary seed application, a moderate level of Indian ricegrass seedling recruitment occurred at two of our study sites in western Nevada, although there was no recruitment at the third site in eastern California. At both Nevada sites, the number of Indian ricegrass seedlings sampled along transects was significantly greater on all plots treated with diversionary seeds than on non-seeded control plots. However, the density of diversionary seeds applied to plots had a marginally non-significant effect on seedling recruitment, and it was not correlated with recruitment patterns among plots. Results suggest that application of a diversionary seed type that is preferred by seed-caching rodents provides a promising passive restoration strategy for target plant species that are dispersed by these rodents.

Longland, William; Ostoja, Steven M.

2013-01-01

446

Blackberry seed extracts and isolated polyphenolic compounds showing protective effect on human lymphocytes DNA.  

PubMed

The tentative identification of seed extracts from 3 cultivars of blackberry (blackberry seed extracts [BSEs]) constituents was performed by LC/UV/MS technique. The identified compounds belonged to ellagitannins, galic acid derivatives, and ellagic acid derivatives. Two ellagitannins, Lambertianin C and Sanguiniin H-6, and an ellagic acid derivative, 4-?-L-arabinofuranosylellagic acid, were isolated using semipreparative High-performance liquid chromatography. The structure elucidations were based on high resolution-mass spectrometry and nuclear magnetic resonance studies. The BSEs and 3 isolated pure compounds were tested for in vitro protective effect on chromosome aberrations in peripheral human lymphocytes using cytochalasin-B blocked micronucleus (MN) assay. The frequency of MN was scored in binucleated cells, and nuclear proliferation index was calculated. Among the tested extracts, the seeds of cv. Thornfree at concentration of 1 ?g/mL exhibit the most prominent effect decreasing the frequency of MN by 62.4%, when compared with the controls cell cultures. Antioxidant potential of pure ellagitannins cannot explain the strong effect of BSEs. The assumption was that better antioxidant effect of BSEs result from synergistic effects of individual compounds contained in the extracts and/or some minor components possessed strong activity. PraCTICAL APPLICATION: Our results provide evidence of protective effects of BSEs and isolated pure compounds on cytogenetic damages in human lymphocytes. Thus, BSEs could exert beneficial effects in quite a few diseases, because many of the biological actions have been attributed to their antioxidant properties. PMID:21824137

Go?evac, Dejan; Teševi?, Vele; Vajs, Vlatka; Milosavljevi?, Slobodan; Stankovi?, Miroslava

2011-09-01

447

A Crunching Colon: Rectal Bezoar Caused by Pumpkin Seed Consumption  

PubMed Central

Rectal seed bezoars are an uncommon cause of fecal impaction, particularly in the United States. Although the literature has reported several cases of phytobezoars composed of various types of seeds, bezoars formed of pumpkin seeds have rarely been reported. We report a case of a man, aged 62 years, with a rectal bezoar composed of pumpkin seeds with complications necessitating extensive treatment, including manual disimpaction and colonoscopy.

Manne, Janaki R.; Rangu, Venu M.; Motapothula, Uma Maheswara R.; Hall, Matthew C.

2012-01-01

448

Physical properties of coriander seeds ( Coriandrum sativum L.)  

Microsoft Academic Search

Physical properties of kernels, grains, and seeds are necessary for the design of equipment to handle, transport, process and store the crop. The physical properties of coriander seeds have been evaluated as a function of seed moisture content, varying from 7.10% to 18.94% (d.b.). In the moisture range, seed length decreased linearly from 4.74 to 4.61mm, and width, thickness, arithmetic

Yalç?n Co?kuner; Er?an Karababa

2007-01-01

449

Research on Grading Detection of the Wheat Seeds  

PubMed Central

Evaluating the merits of the wheat seed is an important significance for wheat breeding. We studied analytic hierarchy process (AHP) for seeds grading by digital image processing techniques in the paper. Firstly, preprocess the collected wheat seed images; extract some parameters, such as area, plumpness, rectangular, and elongation of the seed, and then build the level model. Experiments showed the model is right, and level accuracy rate is more than 95%.

Han, Xian-Zhong; Wang, Ke-Jian; Yuan, Yingchun; Chen, Chen; Liang, Liang

2014-01-01

450

Development of Hybrid Corn and the Seed Corn Industry  

Microsoft Academic Search

This is a history of the development of hybrid corn (Zea maize L.) and of the developing seed corn industry by review of the\\u000a literature and by the personal testimony of colleagues. I identify, describe, and discuss pertinent background germplasm and\\u000a provide a sampling of seed corn company histories. Some highlights of seed organizations and seed improvement associations\\u000a are given.

A. Forrest Troyer

451

Organic substance metabolism during seed germination of Pinus bungeana  

Microsoft Academic Search

The metabolism of fats, proteins and carbohydrates and change of enzyme of seeds ofpinus bungeana during the germination were conducted by the methods of gas-liquid chromatography, flow injection, colorimetric analysis\\u000a of spectrophotometer, to provide theoretical basis for seeds dormancy, germination and storage of seeds of forest tree. The\\u000a results indicate that (1) carbohydrates were first utilized during germination of seed

Shang Jie; Zhao Kentian

1993-01-01

452

Cotton Seed Deterioration: Assessment of some Physiological and Biochemical Aspects  

Microsoft Academic Search

The effect of accelerated aging (AA) was studied in cotton seeds. The cotton seeds were exposed to high temperature (45-48ºC) and humidity (80-90% relative humidity) for 2, 3, 10 and 20 days. Treated and untreated seeds were compared for various vigor tests. The seeds were analyzed for fat acidity and peroxidase level. The germination percentage decreased with AA. There was

SHAHZAD MAQSOOD; AHMAD BASRA; SAJJAD IQBAL

453

Experimental investigation of injection locking of fundamental and subharmonic frequency-modulated active mode-locked laser diodes  

Microsoft Academic Search

Narrow linewidth and stabilized light injection is employed to reduce the phase noise and stabilize the frequencies of individual teeth of an active mode-locked laser diode (ML-LD) which is modulated by both fundamental and subharmonic frequencies of the cavity free-spectral range (FSR). We demonstrate accurate frequency control of the ML-LD using an injection seed light with linewidth of less than

Mitsuhiro Teshima; Kenji Sato; Masafumi Koga

1998-01-01

454

Influence of Ca 2+ in biological stimulating effects of AC magnetic fields on germination of bean seeds  

NASA Astrophysics Data System (ADS)

This study reports an attempt to investigate the effects of AC magnetic field on the seed germination and seedling growth of beans, at different concentrations of CaCl 2, since Ca 2+ is an essential plant nutrient. Bean seeds were exposed to a combination of local geomagnetic field (DC field) and sinusoidal time-varying extremely low frequency (ELF) magnetic field (AC field) 28.3 Hz, 20 ?T AC field tuned to the fundamental cyclotron resonance for calcium ions. . The application of AC field promoted the germination of bean seeds for all CaCl 2 concentrations. There was no significant change of average weight of the radicals for all concentrations of CaCl 2, whereas there was a significant increase of radicals' length for deionized (DD) and distilled DD water and DD water+ Ca 10 mM.

Sakhnini, Lama

455

Enhanced performance of flexible nanocrystalline silicon thin-film solar cells using seed layers with high hydrogen dilution.  

PubMed

Flexible hydrogenated nanocrystalline (nc-Si:H) thin-film solar cells were prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD), and the effect of highly crystalline intrinsic Si seed layers at the initial growth stage of i nc-Si:H absorbers on their structural and electrical properties and on the performance of solar cells was investigated. The crystallization of i nc-Si:H absorbers was significantly enforced by the introduction of highly crystalline seed layers, resulting in the reduction of defect-dense a-Si:H grain boundary and incubation layer thickness. The open circuit voltage of the nc-Si:H solar cells with the seed layers was improved by the decrease of charged defect density in the defect-rich amorphous region. PMID:24266159

Lee, Ji-Eun; Kim, Donghwan; Yoon, Kyung Hoon; Cho, Jun-Sik

2013-12-01

456

Results on artemia cysts, lettuce and tobacco seeds in the Biobloc 4 experiment flown aboard the Soviet biosatellite Cosmos 1129  

SciTech Connect

The effects of space flight factors, in particular the heavy ion component of cosmic rays, on dormant stages of life forms were investigated as part of the Biobloc 4 experiment flown aboard the Cosmos 1129 biosatellite. Artemia cysts and seeds of tobacco and lettuce plants were placed in tubes and in monolayers sandwiched between layers of visual particle track detectors. Although Artemia cysts exposed in the dry state did not differ from ground controls, hydrated cysts exhibited a slight decrease in hatchability and reduced (C-14)O2 incorporation and protein and nucleic acid synthesis. For cysts held in the monolayers, hits by HZE particles were observed to stimulate emergence, hatching and survival. Higher proportions of chromosomal aberrations were found in lettuce seeds hit by HZE particles, while space flight produced a stimulatory effect on both germination rate and abnormality frequency in both hit and nonhit tobacco seeds. 9 references.

Gaubin, Y.; Planel, H.; Gasset, G.; Pianezzi, B.

1983-01-01

457

Mutagenic effects of heavy ion irradiation on rice seeds  

NASA Astrophysics Data System (ADS)

Three varieties of rice seeds were subjected to irradiation using low-energy and medium-energy ions. The damage and mutations induced by the ions were examined. In addition, genetic analysis and gene mapping of spotted leaf (spl) mutants were performed. Low-energy ions had no significant influence on germination, survival or seedling height, except for the survival of Nipponbare. Medium-energy ions had a significant influence on germination and survival but had no significant effect on seedling height. In the low-energy group, among 60,000 M2 plants, 2823 putative morphological mutants were found, and the mutation frequency was approximately 4.71%. In the medium-energy group, 3132 putative morphological mutants were found, and the mutation frequency was approximately 5.22%. Five spl mutants (spl29-spl33) were obtained by ion irradiation, and the heredity of the spl mutants was stable. The characteristics of the spl mutants were found, by genetic analysis and preliminary mapping, to be controlled by a single recessive gene, and spl30 and spl33 were found to be new lesion-mimic mutants.

Xu, Xue; Liu, Binmei; Zhang, Lili; Wu, Yuejin

2012-11-01

458

100W, single mode, single polarization, picosecond, ytterbium doped fibre MOPA frequency doubled to 530 nm  

Microsoft Academic Search

High average power laser sources operating in the picosecond (ps) regime are useful for a wide range of applications including frequency-doubling and pumping of OPOs. Gain switching (GS) of laser diodes provides a practical and low cost method to generate ps pulses at GHz repetition rates and mW average power levels. Such devices represent excellent seeds for high power fiber

K. K. Chen; Shaif-ul Alam; J. R. Hayes; D. Lin; A. Malinowski; D. J. Richardson

2009-01-01

459

UV generation by frequency quadrupling of a Yb-doped fiber amplifier  

Microsoft Academic Search

The pulsed output of a Yb-doped fiber amplifier was frequency doubled and quadrupled to generate visible and UV radiation. When pumped with 150-200 mW at 980 nm and seeded at 1064 nm, the amplifier produced an average power of 90 mW at 1064 nm, 45 mW at 532 nm, and 1.4 mW at 266 nm. These results indicate that frequency-converted

Jeffrey P. Koplow; Dahv A. V. Kliner; Lew Goldberg

1998-01-01

460

Frequency conversion processes in the non-linear organic crystal N-(4-nitrophenyl)- l-prolinol  

Microsoft Academic Search

Crystals of N-(4-nitrophenyl)-l-prolinol (NPP) of large size and of high optical quality are grown in methanol solution starting from toluene nucleated seeds. The high second-order susceptibility of NPP is exp