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1

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...

2

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

3

Performance evaluation of an improved street sweeper  

SciTech Connect

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

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

1985-10-01

4

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...

5

A Vehicle for Research: Using Street Sweepers to Explore the Landscape of Environmental Community Action  

E-print Network

, environmental science, environmental justice, mobile participatory sensing, street sweepers. ACM ClassificationA Vehicle for Research: Using Street Sweepers to Explore the Landscape of Environmental Community platforms to facilitate public awareness of environmental conditions. However, turning such awareness

Aoki, Paul M.

6

IMPROVED STREET SWEEPERS FOR CONTROLLING URBAN INHALABLE PARTICULATE MATTER  

EPA Science Inventory

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

7

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

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

8

Frequency stabilization of a single-frequency Q-switched Tm:YAG laser by using injection seeding technique.  

PubMed

A stable single-frequency Q-switched Tm:YAG laser was demonstrated. The laser was injection seeded by a monolithic nonplanar ring oscillator laser utilizing the ramp-hold-fire technique. The measurements of the output parameters were presented. This paper focused on investigation of the frequency stability of the injection-seeded laser, which was measured by optical heterodyne technique. A method used to restrict the frequency jitter of the laser was discussed. The fluctuation of the laser frequency was reduced from 2.36 MHz (rms) to 1.07 MHz (rms) in 1 h by optimizing the voltage of the piezoelectric translator. PMID:21772412

Zhang, Yunshan; Gao, Chunqing; Gao, Mingwei; Zheng, Yan; Wang, Lei; Wang, Ran

2011-07-20

9

Frequency stabilization of a single-frequency Q-switched Tm:YAG laser by using injection seeding technique  

NASA Astrophysics Data System (ADS)

A stable single-frequency Q-switched Tm:YAG laser was demonstrated. The laser was injection seeded by a monolithic nonplanar ring oscillator laser utilizing the ramp--hold--fire technique. The measurements of the output parameters were presented. This paper focused on investigation of the frequency stability of the injection-seeded laser, which was measured by optical heterodyne technique. A method used to restrict the frequency jitter of the laser was discussed. The fluctuation of the laser frequency was reduced from 2.36MHz (rms) to 1.07MHz (rms) in 1h by optimizing the voltage of the piezoelectric translator.

Zhang, Yunshan; Gao, Chunqing; Gao, Mingwei; Zheng, Yan; Wang, Lei; Wang, Ran

2011-07-01

10

Sectoral sweepers for sensor node management and location estimation in adhoc sensor networks  

Microsoft Academic Search

In this paper the sectoral sweeper scheme is introduced where a central node that has a directional antenna broadcasts tasks. Nodes which receive a task start sensing and generating reports. Hence nodes at a specified region can be activated or deactivated at any time. Tasks are also associated with a unique identification for each region. Sensor nodes include related task

Ayhan Erdogan; Erdal Cayirci; Vedat Coskun

2003-01-01

11

[Effects of litter coverage and watering frequency on seed germination and seedling survival of Castanopsis fissa].  

PubMed

Castanopsis fissa is an important pioneer species commonly used in the restoration of degraded subtropical grassland in southern China. The study on the effects of litter coverage and watering frequency on the seed germination and seedling survival of C. fissa showed that the effects of litter coverage depended on soil moisture condition. When the watering frequency was 1 time per day, litter covering could restrain seed germination and increase seedling mortality; while watering 2 or 3 times per day, the covering would ameliorate soil moisture condition, and benefit seed germination and seedling establishment. The biomass of C. fissa seedlings was enhanced significantly by litter covering. It was suggested that keeping a litter layer on soil surface could benefit the seed germination and seedling survival of C. fissa to restore subtropical shrub land. PMID:19123340

Wang, Jun; Wang, Zhuo-Han; Yang, Long; Ren, Hai

2008-10-01

12

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

13

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

14

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

15

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

DOEpatents

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

Motley, Robert W. (Princeton, NJ); Glanz, James (Lawrenceville, NJ)

1985-01-01

16

Calibration of the Thick and Thin Scintillators for the NSCL/FSU Sweeper Magnet System  

NASA Astrophysics Data System (ADS)

The MoNA (Modular Neutron Array) Sweeper-magnet setup at the NSCL is designed to measure neutron unbound states by full kinematic reconstruction of the neutrons and the decay fragments. One crucial aspect of these coincidence experiments is the particle identification of the charged fragments in the focal plane detectors following the sweeper magnet. The particle ID is achieved by the measurement of the energy-loss and total kinetic energy in large thin and thick plastic scintillation detectors, respectively. The pulse-height of the signals from these detectors is strongly position dependent. In order to achieve accurate Delta-E/E-identification for the fragments it is thus necessary to correct for these position dependencies. A procedure was developed to implement this correction quickly and efficiently for the on-line analysis. The procedure is based on Tcl-scripts sourced in the analysis program SpecTcl in combination with fitting routines in Excel. The performance of this procedure will be presented with data from experiment 05124, which studied neutron unbound states close to the neutron dripline.

Hayes, Anne

2006-10-01

17

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

NASA Astrophysics Data System (ADS)

Experiments have been carried out to investigate the effects of aging on the frequency response of a fine cold-wire located in a flow seeded with oil particles used for laser Doppler anemometry. Transfer functions are shown to depend strongly on the running time. Photo-micrographs show that the contamination effect is due to discrete droplets, the diameter of which increases with running time. Reduction of frequency response is shown to affect at first the high-frequency range and then an intermediate range of frequencies that are larger than the inverse of the oil droplets time constant. Good agreement is found between experimental results and predictions derived from a simple model of the contaminated wire. This contamination process requires testing and cleaning the wire steadily in order to keep a significant frequency response and, if needed, to correct temperature fluctuations.

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

2005-11-01

18

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

19

On the mechanisms of stimulation and inhibition of wheat seed germination by low-frequency magnetic field  

Microsoft Academic Search

Stimulation of wheat seed germination by brief exposure in a 50-Hz electromagnetic field (EMF) is shown to depend on the extent\\u000a of membrane stretching upon seed swelling in sucrose solutions. This again confirms the effect of low-frequency EMF on the\\u000a release of peripheral proteins from membranes. Prolonged exposure, on the contrary, decreases the germination rate and retards\\u000a seedling growth.

S. I. Aksyonov; T. Yu. Grunina; S. N. Goryachev

2007-01-01

20

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

21

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 ?s 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

22

High-frequency plant regeneration from seed-derived callus cultures of Kentucky bluegrass ( Poa pratensis L.)  

Microsoft Academic Search

Shoot regeneration from seed-derived callus cultures of Kentucky bluegrass (Poa pratensis L.) was tested on MS basal medium supplemented with four different growth regulators. Regeneration frequencies for medium supplemented with 10 M 2,4-dichlorophenoxyacetic acid (2,4-D), 60 M 4amino-3, 5,6-picolinic acid (picloram), or 30 M 3,6dichloro-o-anisic acid (dicamba) ranged from 0.4 to 4%. Medium supplemented with 30 M dicamba plus 10

Jeffrey D. Griffin; Margaret S. Dibble

1995-01-01

23

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

PubMed

H(-) beam was successfully extracted from a cesium seeded ion source operated using a field effect transistor inverter power supply as a radio frequency (RF) wave source. High density hydrogen plasma more than 10(19) m(-3) was obtained using an external type antenna with RF frequency of lower than 0.5 MHz. The source was isolated by an isolation transformer and H(-) ion beam was extracted from a single aperture. Acceleration current and extraction current increased with the increase of extraction voltage. Addition of a small amount of cesium vapor into the source enhanced the currents. PMID:22380279

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

2012-02-01

24

Investigation of broadcasting signal overlay using high-frequency filtering characteristics of RSOA in ASE seeded WDM access network  

NASA Astrophysics Data System (ADS)

The simultaneous baseband and broadcasting signal transmission based on wavelength division multiplexing-passive optical network access network are proposed and their experimental verifications are shown. Amplified spontaneous emitting source modulated by broadcasting signal in radio frequency band at reflective semiconductor optical amplifier is provided as seed source for wired signal modulation. The filtered amplified spontaneous emitting source is aligned to each channel and modulated by the downlink baseband signal at RSOA. Simultaneous downstream transmission of baseband and broadcasting signals over 23-km SMF is experimentally verified. Mutual interference between broadcasting and baseband signals, nonlinearity by two tone analysis, and performance variation on temperature are investigated.

Kim, Hyun-Seung; Yang, Se-Hoon; Son, Yong-Hwan; Han, Sang-Kook

2012-02-01

25

Single-frequency operation of diode-pumped 2 microm Q-switched Tm:YAG laser injection seeded by monolithic nonplanar ring laser.  

PubMed

We present a diode-pumped, 2mum single-frequency Q-switched Tm:YAG laser. The Q-switched laser is injection seeded by a monolithic Tm:YAG nonplanar ring oscillator with the ramp-hold-fire technique. The output energy of the 2mum single-frequency Q-switched pulse is 2.23mJ, with a pulse width of 290ns and a repetition rate of 200Hz. From the heterodyne beating measurement, the frequency difference between the seed laser and the Q-switched laser is determined to be 37.66MHz, with a half-width of the symmetric spectrum of about 2 MHz. PMID:20490245

Gao, Chunqing; Lin, Zhifeng; Gao, Mingwei; Zhang, Yunshan; Zhu, Lingni; Wang, Ran; Zheng, Yan

2010-05-20

26

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. PMID:22751213

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

2012-01-01

27

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

28

[On the mechanisms of stimulation and inhibition during germination of wheat seeds in extremely low frequency electromagnetic fields].  

PubMed

It has been shown that the effects of stimulation of germination of wheat seeds by electromagnetic field depend on the degree of membrane tension during imbibition of seeds in sucrose solutions. This provides further confirmation of the influence of electromagnetic fields on the release of proteins from the bound state on the membranes. The prolonged treatment with electromagnetic fields during the imbibition of seeds leads not only to the inhibition of germination of sprouts but also to a decrease in their germinability, which can be as strong as twofold for seeds with the initial low germinability. This is related to the desynchronization of germination processes, caused by the stimulation of the release of proteins and inhibition of another stage during the cell division, the assembly of complex structures. It is noted that the activation of the release of proteins and inhibition of their binding by the action of electromagnetic fields must elevate the cell excitability. The presumably, the excitability of cells determines the effects of magnetic storms and high solar activity on the physiological state of organisms. PMID:17477063

Aksenov, S I; Grunina, T Iu; Goriachev, S N

2007-01-01

29

High power tunable picosecond green laser pulse generation by frequency doubling of an Yb-doped fiber power amplifier seeded by a gain switch laser diode  

NASA Astrophysics Data System (ADS)

A compact tunable high power picosecond green laser pulse source based on frequency doubling of an Yb-doped fiber amplifier seeded by a gain switch laser diode has been developed. The fiber amplifier generates the picosecond infrared pulses with average power of 10.3 W, repetition rate of 1 MHz, pulse duration of 150 ps, and tunable range of 20 nm around 1064 nm. For underwater use, the tunable output infrared pulses are frequency doubled into picosecond green laser pulses, which can be tuned from 527 to 537 nm with average power of more than 1.1 W, corresponding to an overall conversion efficiency of 10.7% by a BBO nonlinear crystal. This kind of laser source will have potential application for underwater optical communication.

Liu, H. J.; Li, X. F.

2011-12-01

30

Co-seeded Er3+:Yb3+ single frequency fiber amplifier with 60 W output power and over 90% TEM(00) content.  

PubMed

We report on the design and fabrication of an Er(3+):Yb(3+) triple clad fiber and on the power scaling of a single frequency fiber amplifier at 1.5 ?m based on that fiber. In addition, we report on mode content measurements in order to reveal the overlap of the amplifier output with the TEM(00) mode. The triple clad design was used to enable high output power levels, a good slope efficiency and an excellent beam quality. A maximum single frequency output power of 61 W at 1.5 ?m could be achieved with the aid of the co-seeding method, which was used to suppress parasitic processes at 1.0 ?m. With a scanning ring cavity the mode content of the amplifier output was analyzed with respect to the TEM modes. For all output power levels the TEM(00) content was above 90%. PMID:25090490

Steinke, M; Croteau, A; Paré, C; Zheng, H; Laperle, P; Proulx, A; Neumann, J; Kracht, D; Wessels, P

2014-07-14

31

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

PubMed

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

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

2013-03-15

32

High-efficiency intra-cavity sum-frequency-generation in a self-seeded image-rotating nanosecond optical parametric oscillator.  

SciTech Connect

We have built and tested a highly efficient source of pulsed 320 nm light based on intra-cavity sum-frequency-generation in a self-injection-seeded image-rotating nanosecond optical parametric oscillator. The four-mirror nonplanar ring optical cavity uses the RISTRA geometry, denoting rotated-image singly-resonant twisted rectangle. The cavity contains a type-II xz-cut KTP crystal pumped by the 532 nm second harmonic of Nd:YAG to generate an 803{approx}nm signal and 1576 nm idler, and a type-II BBO crystal to sum-frequency mix the 532 nm pump and cavity-resonant 803 nm signal to generate 320 nm light. The cavity is configured so pump light passes first through the BBO crystal and then through the KTP crystal with the 320 nm light exiting through the output coupler following the BBO sum-frequency crystal. The cavity output coupler is designed to be a high reflector at 532 nm, have high transmission at 320 nm, and reflect approximately 85% at 803 nm. With this configuration we've obtained 1064 nm to 320 nm optical-to-optical conversion efficiency of 24% and generated single-frequency {lambda} = 320 nm pulses with energies up to 140 mJ.

Armstrong, Darrell Jewell; Smith, Arlee Virgil

2005-02-01

33

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

34

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

35

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

36

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

PubMed

We present a cylindrically curved GaAs x-ray spectrometer with energy resolution ?E/E = 1.1 ×?10(-4) and wave-number resolution of ?k/k = 3 ×?10(-3), allowing plasmon scattering at the resolution limits of the Linac Coherent Light Source (LCLS) x-ray free-electron laser. It spans scattering wavenumbers of 3.6 to 5.2/Å in 100 separate bins, with only 0.34% wavenumber blurring. The dispersion of 0.418 eV/13.5??m agrees with predictions within 1.3%. The reflection homogeneity over the entire wavenumber range was measured and used to normalize the amplitude of scattering spectra. The proposed spectrometer is superior to a mosaic highly annealed pyrolytic graphite spectrometer when the energy resolution needs to be comparable to the LCLS seeded bandwidth of 1 eV and a significant range of wavenumbers must be covered in one exposure. PMID:25273706

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

2014-09-01

37

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

E-print Network

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

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

2014-01-01

38

PRODUCCIÓN Y CALIDAD DE SEMILLAS EN CUATRO POACEAS. EFECTO DE CORTES CON DISTINTAS FRECUENCIAS Y EN DIVERSAS ETAPAS FENOLÓGICAS1 Seed production and quality in four poaceaes. Effects of cutting with different frequency and at different phenological stages1  

Microsoft Academic Search

A B S T R A C T The effect of cutting frequency and phenological stage at cutting on production and quality of seeds was studied on Bromus berteroanus Colla, Hordeum murinum L., Avena barbata Pott ex Link, and Vulpia myuros (L.) C.C. Gmel. The trials were held in a greenhouse under controlled conditions and without water restriction. The phenological

Myrna Johnston R; Alfredo Olivares; Jorge Laura

39

Pomegranate seeds  

NSDL National Science Digital Library

This pomegranate has many seeds inside. These seeds are surrounded individually by red fruit. Some fruits also have many seeds, but all of the seeds are surrounded by the fruit instead of individually, like in an apple.

Peter N/A (None;)

2005-01-01

40

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

41

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

42

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

43

Scattering Seeds  

NSDL National Science Digital Library

In this lesson, students will: 1) Investigate how seeds are dispersed. 2) Understand the variety of seed dispersal that exists in the plant kingdom. 3) Understand how factors in the natural environment can effect how far a seed is dispersed. Included in this one to two day lesson plan are the objectives, needed materials, procedures, adaptations for older students, discussion questions, an evaluation, extensions, suggested reading, links to other sites, vocabulary, and academic standards. Students will collect a variety of seeds and design a wind-dispersed seed mechanism. They can click on a vocabulary word to hear its pronunciation and a sentence using the word. Teachers can purchase the video, The Private Life of Plants 5-Pack (Branching Out) and download comprehension questions and answers. They can link to Teaching Tools to create custom worksheets, puzzles, and quizzes. A printable version of this lesson plan can be downloaded.

Discoveryschool.com; Cahill, Mary

2007-01-01

44

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

PubMed

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

45

Seeding Rangeland  

E-print Network

easily. Following a wildfire, seeding may be necessary to restore the area?s productivity. On abandoned cropland, an ideal seedbed may be prepared without undue expense, but on rangeland, the ideal seedbed is a goal seldom attained because expenses exceed... easily. Following a wildfire, seeding may be necessary to restore the area?s productivity. On abandoned cropland, an ideal seedbed may be prepared without undue expense, but on rangeland, the ideal seedbed is a goal seldom attained because expenses exceed...

Welch, Tommy G.; Hafercamp, Marshall R.

2001-01-04

46

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

SciTech Connect

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

John Hansknecht; Benard Poelker

2006-06-01

47

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.

48

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.

49

Big Seed  

NSDL National Science Digital Library

This free 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

50

Mighty Seeds  

NSDL National Science Digital Library

In this biology experiment, learners plant soybean seeds in plaster of Paris, witnessing firsthand the mighty power and ability of plants to grow in adverse conditions. This is also an excellent activity to touch upon exothermic reactions, as warmth is created when the plaster is mixed.

Cosi

2009-01-01

51

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

52

ANL/APS/LS-327 A New Type of Bunch Compressor and Seeding of a Short Wave Length  

E-print Network

interacting with the electron beam and thus can prepare a significantly higher frequency seed for seeded free-electron lasers. The same approach can be used for a frequency down-conversion that can be useful for generation

Kemner, Ken

53

Pollen-limited seed set in pods of tamarind ( Tamarindus indica L.)  

E-print Network

Introduction A negatively skewed distribution of seeds per pod, where the frequency of many- seeded pods (Lee and Bazaaz, 1982), However, disturban- ces of this negatively skewed distribution have been) of seeds per pod in T. indica: 1) resource limitation, 2) post-fertilization abortion of seeds, and 3

Boyer, Edmond

54

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.

55

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.

56

Bean Seed Imbibition.  

ERIC Educational Resources Information Center

Enables students to examine the time course for seed imbibition and the pressure generated by imbibing seeds. Provides background information, detailed procedures, and ideas for further investigation. (DDR)

Hershey, David R.

1998-01-01

57

Detection of brachytherapy seeds using 3D ultrasound.  

PubMed

Imaging and detection of brachytherapy seeds using transrectal ultrasound (TRUS) remains a challenge for prostate brachytherapy, mainly due to the small size of brachytherapy seeds in relatively low-quality B-mode TRUS images. In this paper, we propose a new solution for brachytherapy seed detection using 3D ultrasound. We use 3D reflected power images computed from ultrasound radio-frequency signals, instead of using conventional B-mode images. Then implanted seeds are detected in 3D local search spaces that are determined by a priori knowledge. Experimental results showed that the proposed solution works well for seed localization in the prostate phantom. PMID:19162791

Wen, Xu; Salcudean, S E

2008-01-01

58

Improvement of Arabidopsis thaliana seed transformation efficiency  

Microsoft Academic Search

Agrobacterium tumefaciens induced transgenosis by treatment of germinatingArabidopsis thaliana seed embryos has been achieved with differentAgrobacterium strains including the strain LBA4404, which was ineffective in seed transformation experiments of the other authors. The\\u000a frequency of transgenosis was increased several times by application of acetosyringone to the growingA. tumefaciens suspension cultures. The DNA demethylating agent 5-azacytidine partly restored the distorted Mendelian

D. PAVINGEROVJk; M. Ond?ej

1995-01-01

59

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

60

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

61

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

62

Mechanisms of long-distance dispersal of seeds by wind  

Microsoft Academic Search

Long-distance dispersal (LDD) is central to species expansion following climate change, re-colonization of disturbed areas and control of pests. The current paradigm is that the frequency and spatial extent of LDD events are extremely difficult to predict. Here we show that mechanistic models coupling seed release and aerodynamics with turbulent transport processes provide accurate probabilistic descriptions of LDD of seeds

Ran Nathan; Gabriel G. Katul; Henry S. Horn; Suvi M. Thomas; Ram Oren; Roni Avissar; Stephen W. Pacala; Simon A. Levin

2002-01-01

63

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

64

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

65

Evaluating Cotton Seed Quality  

E-print Network

, treated and bagged for planting the following season. Producers who plan to save seed from conventional varieties are advised to evaluatr seed quality before the planting season, using procedures such as the free fatty acid test, germination tests...

Boman, Randy

2005-10-05

66

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

67

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

68

SEED Database Requirements  

Microsoft Academic Search

SEED is an acronym for Software Environment to Support the Early Phases in Building Design. The overall architecture of SEED is based on a division of the preliminary design process into phases, each of which addresses a specific task. SEED intends to support each phase by an individual support module based on a shared logic and architecture. The modules envisioned

Robert Coyne; Robert Woodbury; Shang-Chia Chiou; Bongjin Choi; Han Kiliccote; Teng-Weng Chang; Sheng-Fen Chien; Jim Snyder

69

7 CFR 201.15 - Weed seeds.  

Code of Federal Regulations, 2010 CFR

...Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed...transported and shall include noxious weed seeds. [5 FR 31, Jan. 4,...

2010-01-01

70

Switchgrass recruitment from broadcast seed vs. seed fed to cattle  

Microsoft Academic Search

Fecal seeding by livestock may be an effective, low-cost means of rangeland restoration. We compared recruitment of switch- grass (Panicum virgatum L.) from seed fed to cattle and deposited in dung to that of broadcast-seeded plots receiving a comparable number of unfed seed. Although germinability of seed passed through livestock (52 to 62%) was reduced relative to that of broadcast

W. R OCUMPAUGH; S. ARCHER; J. W. STUTH

71

Wheat seed quality - A study on farmers' seed  

Microsoft Academic Search

High quality seed is the key to successful agriculture. Survey results have shown that 64% of Bangladeshi farmers use their own wheat seed year after year, or 26% purchase from other farmers in local markets. Only 10% of the seed is purchased from governments' seed suppliers. As a result, poor seed quality is a significant factor affecting wheat productivity at

Salina P. Banu; J. M. Duxbury; J. G. Lauren; Craig Meisner; Rafiqul Islam

72

Control of Weeds at a Pinyon-Juniper Site by Seeding Grasses  

Microsoft Academic Search

An area seeded to perennial grasses and an adjacent nonseeded area both within a burned Colorado pinyon\\/Utahjuniper (Pinus edulis Engelm.\\/Juniperus osteosperma (Torr.) Little) com­ munity provided an opportunity to contrast frequency of plant species in the two treatments. Lower frequencies for cheatgrass (Bromus tectorum L.) and yellow salsify (Tragopogon dubius Scop.), which are introduced annuals, were found in the seeded

Sherel Goodrich; Dustin Rooks

73

Antibacterial Substances in Seeds  

Microsoft Academic Search

WHILE investigating the physiology of germination, it was noted that micro-organisms occurring on the seeds of certain species proliferated rapidly during germination, whereas the seeds of some other species, germinating under the same conditions, remained sterile. It seemed obvious that certain seeds must contain and release-during germination-compounds that are able to inhibit the growth of certain micro-organisms. In order to

L. Ferenczy

1956-01-01

74

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

75

Seed Dispersal 101  

NSDL National Science Digital Library

This two-minute radio program introduces listeners to the variety of agents that disperse seeds. The program's guest, a plant biologist, cites examples of nonliving and living dispersal agents that include the wind, water, and such animals as birds and bats. He also explains that a plant's fruits or seeds often offer clues about how they are dispersed. The program, which is available here in audio and text, is the first in a series about seed dispersal. Copyright 2005 Eisenhower National Clearinghouse

Planet, Pulse O.

2007-07-26

76

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

77

Ant–seed mutualisms  

Microsoft Academic Search

Invasion by the red imported fire ant, Solenopsis invicta, has had negative impacts on individual animal and plant species, but little is known about how S. invicta affects complex mutualistic relationships. In some eastern forests of North America, 30% of herbaceous species have ant-dispersed seeds. We conducted experiments to determine if fire ants are attracted to seeds of these plant

Jennifer A Zettler; Timothy P Spira; Craig R Allen

2001-01-01

78

Barley Seed Son  

E-print Network

, selling fruit, raising and selling pigs, selling produce from greenhouses, driving tractors, and so on. Most families own cows for milk. ?????????????????????????????????????????????????? ??????? ????? ??????? ?????? ????? ?????? ?????? ?????? ??... (Video) Barley Seed Son ‘Barley Seed Son’ was told by Rgyal mtshan in A mdo Tibetan. Rta rgyugs, a subdivision of Rka phug Administrative Village, is a farming village located in Khams ra Town, Gcan tsa County Town, Rma lho Tibetan...

Rdo rje don 'grub

2011-01-01

79

Planning cloud seeding research  

Microsoft Academic Search

It is suggested that a theory of cloud seeding needs to be developed before seeding experiments can be properly planned and assessed. This theory will arise from improved knowledge of cloud processes gained by the study of natural clouds. Some techniques used in observing shower clouds in Sweden are described, and some preliminary results mentioned.

F. H. Ludlam

1955-01-01

80

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

81

The earliest seeds  

USGS Publications Warehouse

Lagenostomalean-type seeds in bifurcating cupule systems have been discovered in the late Devonian Hampshire Formation of Randolph County, West Virginia, USA (Fig. 1). The associated megaflora, plants from coal balls, and vertebrate and invertebrate faunas demonstrate that the material is Famennian; the microflora indicates a more specific Fa2c age. Consequently, these seeds predate Archaeosperma arnoldii1 from the Fa2d of northeastern Pennsylvania, the oldest previously reported seed. By applying precision fracture, transfer, de??gagement, and thin-section techniques to selected cupules from the more than 100 specimens on hand, we have determined the three-dimensional morphology and histology of the seeds (Fig. 2a-h, k) and cupule systems. A comparison with known late Devonian to early Carboniferous seeds reveals that ours are more primitively organized than all except Genomosperma2,3. ?? 1981 Nature Publishing Group.

Gillespie, W.H.; Rothwell, G.W.; Scheckler, S.E.

1981-01-01

82

Fungicide Seed Treatment and Seed Colour Effects on Seed Vigour and Emergence in Flax  

Microsoft Academic Search

In this study, the effect of chemical seed treatment with Captan 0.2% and Carbendazim 0.15% and seed colour on germination, seed vigour and emergence was studied on two populations of flax that were near-isogenic for seed colour. The results showed that in germination test, chemical seed treatment and seed colour had no significant effect on germination. However, in the vigour

G. SAEIDI; A. A. MOHAMMADI MIRIK

83

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

84

7 CFR 201.15 - Weed seeds.  

Code of Federal Regulations, 2012 CFR

... 3 2012-01-01 2012-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture...REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants...

2012-01-01

85

7 CFR 201.15 - Weed seeds.  

Code of Federal Regulations, 2011 CFR

... 3 2011-01-01 2011-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture...REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants...

2011-01-01

86

7 CFR 201.15 - Weed seeds.  

Code of Federal Regulations, 2013 CFR

... 3 2013-01-01 2013-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture...REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants...

2013-01-01

87

7 CFR 201.15 - Weed seeds.  

... 3 2014-01-01 2014-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture...REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants...

2014-01-01

88

Corn Seed Germination and Vigor Following Freezing during Seed Development  

Microsoft Academic Search

The potential for an early autumn frost to reduce corn (Zea mays L.) seed quality is a concern for seed producers. This study evaluated the effect of freezing rate, freezing temperature (26, 211C) and duration (4, 6 h), ear attachment, and endosperm composition on seed germination and vigor (accelerated aging (AA) and cold test) during seed development and maturation of

James Woltz; Dennis M. TeKrony; Dennis B. Egli

2006-01-01

89

Empty seeds reduce seed predation by birds in Juniperus osteosperma  

E-print Network

Empty seeds reduce seed predation by birds in Juniperus osteosperma MARCELINO FUENTES1 and EUGENE W juniper (Juniperus osteosperma) is one of many plant species that produce large numbers of fruits to demonstrate discrimination based on seed ®lling at the level of whole plants. Keywords: empty seeds; Juniperus

Fuentes, Marcelino

90

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

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

91

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

NASA Technical Reports Server (NTRS)

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

Dubinina, L. G.

1980-01-01

92

Genetically Modified Food Seeds: Genetically Modified Food Seeds: Genetically Modified Food Seeds: Genetically Modified Food Seeds: Genetically Modified Food Seeds: Health, Socioeconomic  

Microsoft Academic Search

Although concerns about genetically modified (GM) food seeds are serious and well-founded, the problems which these seeds raise are usually not unique to GM seeds alone. GM organisms are only one example of problematic new varieties or breeds. Large soybean and other monocultural plantations have serious environmental effects which GM seeds exacerbate. Although GM seeds may benefit large scale commercial

Frank J. Leavitt

93

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

Microsoft Academic Search

Commercial oil-yielding seeds (castor, coconut, neem, peanut, pongamia, rubber and sesame) were collected from different places\\u000a in the state of Tamil Nadu (India) from which 1279 endophytic fungi were isolated. The oil-bearing seeds exhibited rich fungal\\u000a diversity. High Shannon-Index H? was observed with pongamia seeds (2.847) while a low Index occurred for coconut kernel-associated\\u000a mycoflora (1.018). Maximum Colonization Frequency (%)

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

94

Molecular Physiology of Seed Maturation and Seed Storage Protein Biosynthesis  

Microsoft Academic Search

\\u000a Recent progress is presented in order to understand seed protein synthesis in the context of seed maturation, with the main\\u000a emphasis on legume and cereal crop seeds. This review highlights the molecular physiology of seed storage protein synthesis\\u000a and deposition, the genetic background, and the regulatory and signal transduction network of seed maturation. Storage protein\\u000a synthesis is tightly connected to

H. Weber; N. Sreenivasulu; W. Weschke

95

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

96

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

97

Alfalfa Seed Testing.  

E-print Network

of the embryo with part of the outer covering still attached. At the sides are smaller figures giving natural sizes of the seeds. Rib (Plantago laneeolata.) This is one of the weed seeds al- Grass. most universally found in alfalfa growu in northern.... ......... .... . .... ,I-+,Q,: : : : : z-: +A: fi: =: i g; i i j ~i ~l RibGrass,Plantago lance- ........... .... olata. : : : : : : : : : : : : : : Ql: : : : ': : : : w: : : N: : + Pig Weed, Amaranthus re...

Ball, O. M. (Oscar Melville)

1905-01-01

98

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

99

Seed weight variation of Wyoming sagebrush in northern Nevada.  

PubMed

Seed size is a crucial plant trait that may potentially affect not only immediate seedling success but also the subsequent generation. We examined variation in seed weight of Wyoming sagebrush (Artemisia tridentata ssp. wyomingensis Beetle and Young), an excellent candidate species for rangeland restoration. The working hypothesis was that a major fraction of spatial and temporal variability in seed size (weight) of Wyoming sagebrush could be explained by variations in mean monthly temperatures and precipitation. Seed collection was conducted at Battle Mountain and Eden Valley sites in northern Nevada, USA, during November of 2002 and 2003. Frequency distributions of seed weight varied from leptokurtic to platykurtic, and from symmetry to skewness to the right for both sites and years. Mean seed weight varied by a factor of 1.4 between locations and years. Mean seed weight was greater (P < 0.05) in 2003 than in 2002 at both sites. This can partially be attributed to 55% greater precipitation in 2003 than 2002, since mean monthly temperatures were similar (P > 0.05) in all study situations. Simple linear regression showed that monthly precipitation (March to November) explained 85% of the total variation in mean seed weight (P = 0.079). Since the relationship between mean monthly temperature (June-November) and mean seed weight was not significant (r2 = 0.00, P = 0.431), this emphasizes the importance of precipitation as an important determinant of mean seed weight. Our results suggest that the precipitation regime to which the mother plant is exposed can have a significant effect on sizes of seeds produced. Hence, seasonal changes in water availability would tend to alter size distributions of produced offspring. PMID:16524249

Busso, Carlos A; Perryman, Barry L

2005-12-01

100

Seed Iron in Diverse Soybean Genotypes  

Microsoft Academic Search

Iron (Fe) in the embryo fraction of soybean (Glycine max L.) seed is important for seedling growth. Seed Fe accumulation in 27 soybean genotypes differing in seed size was studied at two field locations. Mean seed weight was 148 mg seed with mean individual genotypic values ranging from 68 to 217 mg seed. Percentage of total seed dry matter in

John T. Moraghan; Ted C. Helms

2005-01-01

101

Seed Transmission of Pseudoperonospora cubensis  

PubMed Central

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

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

2014-01-01

102

Seeding rate and seed size as management techniques for ryegrass (Lolium Multiflorum, Lam) in winter wheat  

E-print Network

Higher seeding rates and larger seed sizes could enhance the competitiveness of wheat with ryegrass. Growth room and field research evaluated the effects of wheat seeding rates and seed size in competition with Italian ryegrass. Winter wheat seeds...

Cook, Casey Lee

2005-08-29

103

Tracking wind-dispersed seeds using (15) N-isotope enrichment.  

PubMed

Seed dispersal influences a wide range of ecological processes. However, measuring dispersal patterns, particularly long-distance dispersal, has been a difficult task. Marking bird-dispersed seeds with stable (15) N isotopes has been shown to be a user-friendly method to trace seed dispersal. In this study, we determined whether (15) N urea solution could be used to enrich seeds of two common wind-dispersed plants, Eupatorium glaucescens (Asteraceae) and Sericocarpus tortifolius (Asteraceae). We further tested if the water type (distilled versus tap) in (15) N urea solutions influences the level and variability of enrichment of plant seeds, and if increasing spraying frequency per se increases enrichment. Because droughts may lower seed set or kill plants, we wanted to investigate if the additional use of an externally applied anti-transpirant affects the intake of externally applied (15) N into seeds. The results demonstrate that (15) N enrichment of seeds can facilitate dispersal experiments with wind-dispersed plants. The use of distilled water in (15) N urea solutions did not increase (15) N enrichment compared to tap water. Further, enrichment was more efficient at lower spray frequencies. Both the use of tap water and low frequencies could lower time, effort and project costs. The results suggest that species can be protected from drought using an anti-transpirant without decreasing the incorporation of (15) N into seeds. PMID:25174806

Forster, C; Herrmann, J D

2014-11-01

104

An integrated injection seeded THz source and amplifier for time-domain spectroscopy  

E-print Network

An integrated injection seeded THz source and amplifier for time-domain spectroscopy J. Maysonnave, XXXX A terahertz (THz) frequency quantum cascade laser (QCL) is used as an integrated injection seeded source and amplifier for use in THz time-domain spectroscopy. A THz input pulse is generated inside a QCL

Paris-Sud XI, Université de

105

When Will Plant Morphology Affect the Shape of a Seed Dispersal “Kernel”?  

Microsoft Academic Search

Most models of dispersal assume that plants are point sources. In reality, the scale in height over which seed sources are distributed is often of the same order as the scale in distance over which most individual seeds are dispersed. But is this sufficient to affect the fundamental shapes of dispersal frequency distributions? Most published conclusions about the effects of

R. D. COUSENS; A. A. RAWLINSON

2001-01-01

106

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

107

Empty seeds reduce seed predation by birds in Juniperus osteosperma  

Microsoft Academic Search

Utah juniper (Juniperus osteosperma) is one of many plant species that produce large numbers of fruits containing parthenocarpic or otherwise empty or inviable seeds. We tested the hypothesis that production of empty fruits in this species results in reduced levels of predation on fertile seeds. In a population in west-central Utah, we estimated the proportion of fruits with filled seeds

Marcelino Fuentes; Eugene W. Schupp

1998-01-01

108

Seeds of confusion : the impact of policies on seed systems  

Microsoft Academic Search

Seed is basic to crop production. Next to its importance in production, food security and rural development, seed is a key element in many debates about technology development and transfer, biodiversity, globalisation and equity. The sustainable availability of good quality seed is thus an important development issue. This study deals with the impact different types of regulation have on how

N. P. Louwaars

2007-01-01

109

Chia seed oil  

Microsoft Academic Search

Summary  The results of the determination of the chemical composition of chia seed oil are furnished below. The composition of two\\u000a samples of linseed oil determined by Kaufmann and Keller9 is given for comparison.\\u000a \\u000a \\u000a \\u000a The chia seed oil contains a very small amount of oleic glyceride—much less than linseed oil, practically the same amount\\u000a of linolenic glyceride as the Calcutta linseed

WALTER F. BAUGItMAN; George S. Jamieson

1929-01-01

110

Lignins of Rumex acetosa Seeds  

Microsoft Academic Search

Spinach seeds were analyzed quantitatively. Wilstetter lignin was isolated and characterized by alkaline hydrolysis of spinach seed-lignocarbohydrate complex. Its elemental composition and molecular weight were determined. Its IR spectrum was analyzed.

G. N. Dalimova; D. N. Dalimov; M. K. Bkhatt

2004-01-01

111

Healthy food trends -- chia seeds  

MedlinePLUS

... Some think chia seeds may help with weight loss and other risk factors, but this has not been proven. Chia seeds are also high in calcium , iron , and magnesium . Just one little tablespoon will give ...

112

Automated Seed Manipulation and Planting.  

National Technical Information Service (NTIS)

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 t...

R. Garcia, J. Herrera, S. Holcomb, P. Kelly, S. Myers

1988-01-01

113

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

114

Tree Seed Technology Training Course: Student Outline.  

ERIC Educational Resources Information Center

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

Bonner, F. T.; And Others

115

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

116

Somatic polymorphism and seed dispersal  

Microsoft Academic Search

SOMATIC seed polymorphism is the production of seeds of different morphologies or behaviour on different parts of the same plant and is a somatic differentiation rather than the result of genetic segregation1. This phenomenon appears to be confined to a limited number of families of higher plants (for example, Cruciferae, Compositae, Chenopodiaceae, Gramineae). Seed produced within a somatic polymorphism may

Anne E. Sorensen

1978-01-01

117

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

118

Cloud Seeding By: Julie Walter  

E-print Network

Cloud Seeding By: Julie Walter Air Chem and Pollution #12;History · In Kurt Vonnegut's 1963 novel nuclei catalyst. #12;Cloud Seeding is... · a process that uses a product such as Silver Iodide or dry ice the freezing process of the ice nuclei in clouds. static seeding- involves cumulus clouds traveling west

Toohey, Darin W.

119

Morphological Analysis of Rubus Seed  

Microsoft Academic Search

The genus Rubus exhibits morphological diversity and a wide range of reproductive systems and habitats. We examined seed coat ultrastructural morphology of seed accessions of 10 subgenera preserved at the US Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), Corvallis, Oregon, using scanning electron microscopy (SEM). SEM images were taken of 56 seed samples collected worldwide. Macromorphological

Sugae Wada; Barbara M. Reed

120

Seed Cotton Handling & Storage  

E-print Network

Seed Cotton Handling & Storage #12;S.W. Searcy Texas A&M University College Station, Texas M) Lubbock, Texas E.M. Barnes Cotton Incorporated Cary, North Carolina Acknowledgements: Special thanks for the production of this document has been provided by Cotton Incorporated, America's Cotton Producers

Mukhtar, Saqib

121

Grass and grain seeds  

NSDL National Science Digital Library

Many types of grasses grow back after they have been cut back or mowed. Some weeds also do this, but other kinds of weeds stop growing once cut. Grains are seeds, but they are also valuable sources of food for humans and animals.

Olivia Worland (Purdue University;Biological Sciences)

2008-06-03

122

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. PMID:17071633

YAMAZAKI, JUN; MIYOSHI, KAZUMITSU

2006-01-01

123

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

PubMed

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

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

2014-10-01

124

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

PubMed Central

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

Perea, Ramon; Venturas, Martin; Gil, Luis

2013-01-01

125

Injection-seeded Ho:YAG laser at room temperature by monolithic nonplanar ring laser  

Microsoft Academic Search

We demonstrated a 1.91 ?m-pumped, injection-seeded Ho:YAG laser operating at room-temperature. Single-frequency, nearly transform-limited Q-switched operation of the laser was achieved by injection-seeding. Using a monolithic Ho:YAG nonplanar ring oscillator (NPRO) as the seed laser, the 11 mJ single-frequency Q-switched Ho:YAG laser at 110 Hz with a pulse width of 110 ns was obtained. The beam quality factor was measured

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

2012-01-01

126

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

127

USING LOCAL SEEDS IN  

Microsoft Academic Search

Choice among local, non-local, and cultivar seeds for restoring native ecosystems is not purely an academic question—it also has practical consequences. In this article we summarize a series of genetic and competition studies of big bluestem (Andropogon gerardii Vitman. [Poaceae]), Indian grass (Sorghastrum nutans (L.) Nash. [Poaceae]), and purple prairie clover (Dalea purpurea Vent.[Fabaceae]) from remnant and restored Illinois (local)

Danny J Gustafson; David J Gibson; Daniel L Nickrent

2005-01-01

128

Network models of frugivory and seed dispersal: Challenges and opportunities  

NASA Astrophysics Data System (ADS)

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

Carlo, Tomás A.; Yang, Suann

2011-11-01

129

Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887  

SciTech Connect

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. [Academy of Sciences, Moscow (Russian Federation); [Institute of Biomedical Problems, Moscow (R); [Moscow Physical-Engineering Inst. (Russian Federation)

1995-03-01

130

Spatial variability in seed predation in Primula farinosa: local population legacy versus patch selection.  

PubMed

Spatio-temporal variation in seed predation may strongly influence both plant population dynamics and selection on plant traits. The intensity of seed predation may depend on a number of factors, but the relative importance of previous predator abundance ("local legacy"), spatial distribution of the host plant, environmental factors and plant characteristics has been explored in few species. We monitored seed predation in the perennial herb Primula farinosa, which is dimorphic for scape length, during 5 consecutive years, in a 10-km x 4-km area comprising 79 P. farinosa populations. A transplant experiment showed that the seed predator, the oligophagous tortricid moth Falseuncaria ruficiliana, was not dispersal limited at the spatial scale corresponding to typical distances between P. farinosa populations. Correlations between population characteristics and incidence and intensity of seed predation varied among years. The incidence of the seed predator was positively correlated with host population size and mean number of flowers, while intensity of seed predation in occupied patches was positively related to the frequency of the long-scaped morph in 2 years and negatively related to host population size in 1 year. In both scape morphs, predation tended to increase with increasing frequency of the long morph. There was no evidence of a local legacy; incidence and intensity of seed predation were not related to the abundance of the seed predator in the population in the previous year. Taken together, the results indicate that among-population variation in seed predation intensity is determined largely by patch selection and that the seed predator's preference for tall and many-flowered inflorescences may not only affect selection on plant traits within host plant populations, but also the overall intensity of seed predation. PMID:19214585

Vanhoenacker, Didrik; Agren, Jon; Ehrlén, Johan

2009-05-01

131

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

132

Sweeper-Agent Recommendations-Tree Early Scheme  

E-print Network

of Information and Communication technology University of Trento - ITALY {sameh, paolo.giorgini} @ dit). Objects-Identification related technologies are encouraging scholars to build up Smart Ambient systems Technology in forming a virtual community between environmental objects. This virtual community is reasonably

133

Seed Dispersal by Japanese Macaques  

Microsoft Academic Search

\\u000a Seed dispersal is a crucial process in recruitment of plant populations, as well as for pollen dispersal. The location of\\u000a dispersed seeds affects the survival of seedlings and the spatial distribution pattern of plants. Plants employ various strategies\\u000a for effective seed dispersal, and diaspores have unique structures that utilize biotic and\\/or abiotic factors such as fleshy\\u000a arils for endozoochory, thorny

Tatsuya Otani

134

Post-fire seeding on Wyoming big sagebrush ecological sites: regression analyses of seeded nonnative and native species densities.  

PubMed

Since the mid-1980s, sagebrush rangelands in the Great Basin of the United States have experienced more frequent and larger wildfires. These fires affect livestock forage, the sagebrush/grasses/forbs mosaic that is important for many wildlife species (e.g., the greater sage grouse (Centrocercus urophasianus)), post-fire flammability and fire frequency. When a sagebrush, especially a Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis (Beetle & A. Young)), dominated area largely devoid of herbaceous perennials burns, it often transitions to an annual dominated and highly flammable plant community that thereafter excludes sagebrush and native perennials. Considerable effort is devoted to revegetating rangeland following fire, but to date there has been very little analysis of the factors that lead to the success of this revegetation. This paper utilizes a revegetation monitoring dataset to examine the densities of three key types of vegetation, specifically nonnative seeded grasses, nonnative seeded forbs, and native Wyoming big sagebrush, at several points in time following seeding. We find that unlike forbs, increasing the seeding rates for grasses does not appear to increase their density (at least for the sites and seeding rates we examined). Also, seeding Wyoming big sagebrush increases its density with time since fire. Seeding of grasses and forbs is less successful at locations that were dominated primarily by annual grasses (cheatgrass (Bromus tectorum L.)), and devoid of shrubs, prior to wildfire. This supports the hypothesis of a "closing window of opportunity" for seeding at locations that burned sagebrush for the first time in recent history. PMID:18790557

Eiswerth, Mark E; Krauter, Karl; Swanson, Sherman R; Zielinski, Mike

2009-02-01

135

Selection by a predispersal seed predator constrains the evolution of avian seed dispersal in pines  

Microsoft Academic Search

Summary 1. Previous studies have demonstrated that wind dispersal is an effective mode of seed dispersal for pines ( Pinus , Pinaceae) with seeds weighing <90 mg, but not for larger- seeded ( ? 90 mg) pines. Consequently, most large-seeded pines rely on birds in the family Corvidae for seed dispersal, but some do not, and most of their seeds

A. M. SIEPIELSKI; C. W. BENKMAN

2007-01-01

136

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

137

Successful creation of species-rich grassland on road verges depend on various methods for seed transfer  

Microsoft Academic Search

This study focused on a suite of vascular plant species (six herbs and two grasses) common to traditionally managed, species-rich grasslands in Western Norway. We assessed the suitability of two species transfer methods (seed sowing and soil seed bank) for restoration of species-rich grassland on a newly established road verge. We compared the species' frequencies one and three years after

J.-F. Nordbakken; K. Rydgren; I. Auestad; I. Austad

2010-01-01

138

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

139

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

140

Training for Certification: Seed Treatment.  

ERIC Educational Resources Information Center

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

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

141

?- and ?-Amylases in seed germination  

Microsoft Academic Search

During the first 24 h of germination of wheat seeds, starch is hydrolysed by free ?-amylase. In the next 24 h, some amount\\u000a of inactive form of ?-amylase is converted into active form and this together with ?-amylase synthesizedde novo brings about the hydrolysis of starch. The amount of ?-amylase is greater in seeds with embryo intact than with embryo

A. K. Goswami; M. K. Jain; B. Paul

1977-01-01

142

Seed dormancy in alpine species  

PubMed Central

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

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

2011-01-01

143

Wildfire, Ryegrass Seeding, and Watershed Rehabilitation1  

E-print Network

Abstract: Aerial seeding of Italian annual ryegrass (Lolium multiflorum) is a common, but controversial seeded with either Italian annual ryegrass (Lolium multiflorum) or soft chess (Bromus mollis, also

Standiford, Richard B.

144

Seed-coat thickness data clarify seed sizeseed-bank persistence trade-offs in Abutilon theophrasti (Malvaceae)  

E-print Network

Seed-coat thickness data clarify seed size­seed-bank persistence trade-offs in Abutilon theophrasti previously correlated with seed survival in soil. To do this, we used Abutilon theophrasti accessions and seed-bank persistence. Keywords: Abutilon theophrasti, arable weed, seed defence, seed dormancy, seed

Sims, Gerald K.

145

Wet deposition of the seeding agent after weather modification activities.  

PubMed

Weather modification activities are performed mostly by cloud seeding. Some operational projects have been conducted for more than a half century and cover planetary scales. These activities have led to large amounts of seeding agents being deposited on the ground in precipitation. The main intent of this paper is to identify the spatial pattern of silver iodide deposits after hail suppression. The spatial pattern of silver iodide deposits is determined using the weather modification project measurements from seeding agent reports, two weather radars and 316 launching sites during a 5-year period. The estimated spatial distribution of the deposits is not uniform, with the maximum silver iodide amount located in the southern part of the study area (up to 140 ?g m(-2)). Our results are comparable with the measurements performed by chemical analyses during other cloud seeding experiments. The maximum location coincides well with that of the maximum seeded hailstorm precipitation frequency. A new method for identifying the spatial pattern of wet-deposited material has been established. The location with the maximum amount is found. This method would be important as a means of placing samplers and monitoring at the representative sites because those are where most weather modification projects would be performed in the future. PMID:23589275

Curi?, Mladjen; Janc, Dejan

2013-09-01

146

Seed biology and in vitro seed germination of Cypripedium.  

PubMed

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

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

2014-12-01

147

Selective injection locking of a multi-mode semiconductor laser to a multi-frequency reference beam  

NASA Astrophysics Data System (ADS)

Injection locking is a well known and commonly used method for coherent light amplification. Usually injection locking is obtained on a single-mode laser injected by a single-frequency seeding beam. In this work we show that selective injection locking of a single-frequency may also be achieved on a multi-mode semiconductor laser injected by a multi-frequency seeding beam, if the slave laser provides sufficient frequency filtering. This selective injection locking condition depends critically on the frequency detuning between the free-running slave emission frequency and each injected frequency component. Stable selective injection locking to a set of three seeding components separated by 1.2 GHz is obtained. This system provides an amplification up to 37 dB of each component. This result suggests that, using distinct slave lasers for each frequency line, a set of mutually coherent high-power radiation modes can be tuned in the GHz frequency domain.

Srinivas Pramod, Mysore; Yang, Tao; Pandey, Kanhaiya; Giudici, Massimo; Wilkowski, David

2014-07-01

148

[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

149

Mobilization of seed protein reserves.  

PubMed

The mobilization of seed storage proteins upon seed imbibition and germination is a crucial process in the establishment of the seedling. Storage proteins fold compactly, presenting only a few vulnerable regions for initial proteolytic digestion. Evolutionarily related storage proteins have similar three-dimensional structure, and thus tend to be initially cleaved at similar sites. The initial cleavage makes possible subsequent rapid and extensive breakdown catalyzed by endo- and exopeptidases. The proteolytic enzymes that degrade the storage proteins during mobilization identified so far are mostly cysteine proteases, but also include serine, aspartic and metalloproteases. Plants often ensure early initiation of storage protein mobilization by depositing active proteases during seed maturation, in the very compartments where storage proteins are sequestered. Various means are used in such cases to prevent proteolytic attack until after imbibition of the seed with water. This constraint, however, is not always enforced as the dry seeds of some plant species contain proteolytic intermediates as a result of limited proteolysis of some storage proteins. Besides addressing fundamental questions in plant protein metabolism, studies of the mobilization of storage proteins will point out proteolytic events to avoid in large-scale production of cloned products in seeds. Conversely, proteolytic enzymes may be applied toward reduction of food allergens, many of which are seed storage proteins. PMID:22017287

Tan-Wilson, Anna L; Wilson, Karl A

2012-05-01

150

[Metabolic control of seed germination].  

PubMed

We have used proteomics to better characterize germination and early seedling vigor in sugarbeet. Our strategy includes (1) construction of proteome reference maps for dry and germinating seeds of a high-vigor reference seed lot; (2) investigation of the specific tissue accumulation of proteins (root, cotyledon, perisperm); (3) investigation of changes in protein expression profiles detected in the reference seed lot subjected to different vigor-modifying treatments, e.g. aging and/or priming. More than 1 000 sugarbeet seed proteins have been identified by LC/MS-MS mass spectrometry (albumins, globulins and glutelins have been analyzed separately). Due to the conservation of protein sequences and the quality of MS sequencing (more than 10 000 peptide sequences have been obtained), the success rate of protein identification was on the average of 80%. This is to our knowledge the best detailed proteome analysis ever carried out in seeds. The data allowed us to build a detailed metabolic chart of the sugarbeet seed, generating new insights into the molecular mechanisms determining the development of a new seedling. Also, the proteome of a seed-storage tissue as the perisperm is described for the first time. PMID:18980744

Catusse, Julie; Strub, Jean-Marc; Job, Claudette; Van Dorsselaer, Alain; Job, Dominique

2008-01-01

151

Genomic dissection of the seed  

PubMed Central

Seeds play an integral role in the global food supply and account for more than 70% of the calories that we consume on a daily basis. To meet the demands of an increasing population, scientists are turning to seed genomics research to find new and innovative ways to increase food production. Seed genomics is evolving rapidly, and the information produced from seed genomics research has exploded over the past two decades. Advances in modern sequencing strategies that profile every molecule in every cell, tissue, and organ and the emergence of new model systems have provided the tools necessary to unravel many of the biological processes underlying seed development. Despite these advances, the analyses and mining of existing seed genomics data remain a monumental task for plant biologists. This review summarizes seed region and subregion genomic data that are currently available for existing and emerging oilseed models. We provide insight into the development of tools on how to analyze large-scale datasets. PMID:25309563

Becker, Michael G.; Hsu, Ssu-Wei; Harada, John J.; Belmonte, Mark F.

2014-01-01

152

Alfalfa… for Forage and Seed.  

E-print Network

on the soil, condition of the seed- I seed quality. In the eastern half of the nd where alfalfa is to be irrigated, 15 to ~ds per acre usually assure a good stand. gated seedings in the western half of the lay be made at the rate of 12 to 15 pounds... and difficulty in curing. VARIETIES Varieties of alfalfa popular in the United States are divided into four groups; common, Turkistan, variegated and nonhardy. The com- mon group includes Southwestern, Kansas and other common varieties that have developed...

Trew, E. M.

1957-01-01

153

Physical Properties of Sunflower Seeds  

Microsoft Academic Search

Physical dproperties of sunflower seeds and kernels were evaluated as a function of moisture content. At 6·2% m.c.d.b., the average length, width, thickness and unit mass of the seed were 9·52mm, 5·12mm, 3·27mm and 0·049g respectively. Corresponding values for the kernel were 8·28mm, 4·09mm, 2·43mm and 0·034g. The mean equivalent diameter and sphericity of the seed were 5·39mm and 0·57

R. K. Gupta; S. K. Das

1997-01-01

154

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

155

Self fertilization and seed set in Trifolium repens L. by in situ and in vitro pollination  

Microsoft Academic Search

The frequency of seed formation has been determined from self-pollination in situ (by hand) and in vitro for Trifolium repens. Selfing in situ was measured over a period of 3 years in which plants were held either at 35 °C for 24 h post-pollination (1984 and 1985) or held at ambient temperatures (1986). Mean yield of self-seed per 100 florets

G. C. Douglas; V. Connolly

1989-01-01

156

Effects of low-level microwave radiation on germination and growth rate in corn seeds  

Microsoft Academic Search

Experiments were conducted to investigate the effects of microwave radiation on germination and growth rate in corn seeds. Specimens were irradiated in an anechoic chamber, for 22 to 24 h, at CW power density levels from 10 mW\\/cm2to 30 mW\\/cm2. The radiation frequency was 9 GHz. Marked inhibition of seed germination was observed in radiated specimens, probably as a result

J. Bigu-Del-Blanco; J. M. Bristow; C. Romero-Sierra

1977-01-01

157

Effect of seed layer on the growth of well-aligned ZnO nanowires  

Microsoft Academic Search

We demonstrate that vertical well-aligned crystalline ZnO nanowire arrays were grown on ZnO\\/glass substrates by a low-temperature solution method. Different thicknesses of ZnO seed layers on glass substrates were prepared by radio-frequency sputtering. In this work it was found that the morphology of ZnO nanowires strongly depends on the thickness of ZnO seed layers. The average diameter of nanowires is

Liang-Wen Ji; Shi-Ming Peng; Jun-Sheng Wu; Wei-Shun Shih; Cheng-Zhi Wu; I-Tseng Tang

2009-01-01

158

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

159

46 CFR 148.310 - Seed cake.  

Code of Federal Regulations, 2011 CFR

...Special Requirements for Certain Materials § 148.310 Seed cake. (a) This part does not apply to solvent-extracted rape seed meal, pellets, soya bean meal, cotton seed meal, or sunflower seed meal that— (1) Contains a maximum of 4...

2011-10-01

160

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

161

SEED ORCHARDS ON RECLAIMED MINED LAND  

Microsoft Academic Search

Reclaimed mined lands often have restricted public access, a situation that could encourage sagebrush seed growers to invest in methods for increasing seed production and improving seed purity and quality. I tested the agronomic benefit of 2 seeding methods and fabric mulch and a cross-linked polyacrylamide polymer soil amendment by using these practices to establish 3 Wyoming big sagebrush (Artemisia

D Terrance Booth

2005-01-01

162

Effects of cloud seeding activities on the distribution of rainfall in the Texas High Plains  

E-print Network

: Professor John F. Griffiths This research investigates the effects of cloud seeding activities on the distributions of rainfall totals and number of rain days in the Iligh Plains region of West Texas. Rainfall data of target and control areas were... examined to determine if cloud seeding led to greater or lesser rain in the seeded region than over adjacent areas. The monthly rainfall and rain-day data for a 34-yr period were analyzed. The frequency distributions of the observed rainfall and rain...

Bomar, George Wayne

2012-06-07

163

Comments on relationships between native seed preferences of shrub-steppe granivores and seed nutritional characteristics  

Microsoft Academic Search

Kelrick et al. (1986) argued that seed preferences of desert granivores are strongly influenced by soluble carbohydrate contents of native seed species. They assumed that bitterbrush (Purshia tridentata) seeds are eaten in their entirety by rodents, but in fact these granivores eat only embryos of bitterbrush seeds. Embryos have a much lower percentage of soluble carbohydrate than whole bitterbrush seeds,

Stephen H. Jenkins

1988-01-01

164

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

Microsoft Academic Search

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

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

2011-01-01

165

Characteristics of pumpkin seed oil  

Microsoft Academic Search

Eighteen samples of pumpkin seed oil were examined and the following indices determined: specific gravity, refractive index,\\u000a saponification number, iodine value, unsaponifiable matter, free fatty acids, and peroxide value.

V. V. Markovic; L. V. Bastic

1976-01-01

166

Physical Properties of Cumin Seed  

Microsoft Academic Search

The physical properties of cumin seed were evaluated as a function of moisture content. The average length, breadth and thickness were 5·61, 1·77 and 1·55 mm respectively. In the moisture range from 7 to 22% d.b., studies on dried or rewetted cumin seed showed that bulk density initially increased from 477 to 502 kg\\/m3then decreased from 502 to 410 kg\\/m3,

K. K. Singh; T. K. Goswami

1996-01-01

167

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. PMID:23185340

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

2012-01-01

168

Ben (moringa) seed oil  

Microsoft Academic Search

Summary  A brief description of the tree Moringa oleifera, flowers and fruits has been given. The oil expressed from seed produced\\u000a in Haiti, the subject of this investigation, gave the following characteristics:\\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Refractive index at 25 C. 1.4671\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Iodine number (Hanus) 68\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Saponification value 186.4\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Acid value 0.74\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Unsaponifiable matter 1.5 per cent.\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a The results indicated

George S. Jamieson

1939-01-01

169

In vitro comparative study of vibro-acoustography versus pulse-echo ultrasound in imaging permanent prostate brachytherapy seeds  

PubMed Central

Background Permanent prostate brachytherapy (PPB) is a common treatment for early stage prostate cancer. While the modern approach using trans-rectal ultrasound guidance has demonstrated excellent outcome, the efficacy of PPB depends on achieving complete radiation dose coverage of the prostate by obtaining a proper radiation source (seed) distribution. Currently, brachytherapy seed placement is guided by trans-rectal ultrasound imaging and fluoroscopy. A significant percentage of seeds are not detected by trans-rectal ultrasound because certain seed orientations are invisible making accurate intra-operative feedback of radiation dosimetry very difficult, if not impossible. Therefore, intra-operative correction of suboptimal seed distributions cannot easily be done with current methods. Vibro-acoustography (VA) is an imaging modality that is capable of imaging solids at any orientation, and the resulting images are speckle free. Objective and methods The purpose of this study is to compare the capabilities of VA and pulse-echo ultrasound in imaging PPB seeds at various angles and show the sensitivity of detection to seed orientation. In the VA experiment, two intersecting ultrasound beams driven at f1 = 3.00 MHz and f2 = 3.020 MHz respectively were focused on the seeds attached to a latex membrane while the amplitude of the acoustic emission produced at the difference frequency 20 kHz was detected by a low frequency hydrophone. Results Finite element simulations and results of experiments conducted under well-controlled conditions in a water tank on a series of seeds indicate that the seeds can be detected at any orientation with VA, whereas pulse-echo ultrasound is very sensitive to the seed orientation. Conclusion It is concluded that vibro-acoustography is superior to pulse-echo ultrasound for detection of PPB seeds. PMID:18538365

Mitri, F.G.; Davis, B.J.; Greenleaf, J.F.; Fatemi, M.

2010-01-01

170

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.

171

Experimental Evaluation of Seed Limitation in Alpine Snowbed Plants  

PubMed Central

Background The distribution and abundance of plants is controlled by the availability of seeds and of sites suitable for establishment. The relative importance of these two constraints is still contentious and possibly varies among species and ecosystems. In alpine landscapes, the role of seed limitation has traditionally been neglected, and the role of abiotic gradients emphasized. Methodology/Principal Findings We evaluated the importance of seed limitation for the incidence of four alpine snowbed species (Achillea atrata L., Achillea clusiana Tausch, Arabis caerulea L., Gnaphalium hoppeanum W. D. J. Koch) in local plant communities by comparing seedling emergence, seedling, juvenile and adult survival, juvenile and adult growth, flowering frequency as well as population growth rates ? of experimental plants transplanted into snowbed patches which were either occupied or unoccupied by the focal species. In addition, we accounted for possible effects of competition or facilitation on these rates by including a measure of neighbourhood biomass into the analysis. We found that only A. caerulea had significantly lower seedling and adult survival as well as a lower population growth rate in unoccupied sites whereas the vital rates of the other three species did not differ among occupied and unoccupied sites. By contrast, all species were sensitive to competitive effects of the surrounding vegetation in terms of at least one of the studied rates. Conclusions/Significance We conclude that seed and site limitation jointly determine the species composition of these snowbed plant communities and that constraining site factors include both abiotic conditions and biotic interactions. The traditional focus on abiotic gradients for explaining alpine plant distribution hence appears lopsided. The influence of seed limitation on the current distribution of these plants casts doubt on their ability to readily track shifting habitats under climate change unless seed production is considerably enhanced under a warmer climate. PMID:21738694

2011-01-01

172

Reconciling Seed Dispersal and Seed Bank Observations to Predict Smooth Brome  

E-print Network

Reconciling Seed Dispersal and Seed Bank Observations to Predict Smooth Brome (Bromus inermis for their establishment. Nomenclature: Smooth brome, Bromus inermis Leyss. Key words: Biological invasions, plant

Kenkel, Norm

173

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. PMID:24805968

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

2014-01-01

174

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

PubMed

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

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

2014-11-01

175

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

176

Cotton Planting Seed and Related Fiber Qualities.  

E-print Network

of Cotton Planting Seed, 1953 Eig,ht-tenths of the Rowden seed sold was produced in Texas. Most of the remainder was from Arkansas. Nearly all of the Mebane types were produced in Texas (Table 12). Seed of the certified and registered grade were... of Cotton Planting Seed, 1953 Eig,ht-tenths of the Rowden seed sold was produced in Texas. Most of the remainder was from Arkansas. Nearly all of the Mebane types were produced in Texas (Table 12). Seed of the certified and registered grade were...

Paulson, W. E.; Ward, J. M.

1956-01-01

177

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

178

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. PMID:22511952

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

2012-01-01

179

Seed mucilage improves seedling emergence of a sand desert shrub.  

PubMed

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

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

2012-01-01

180

Soil warming increases plant species richness but decreases germination from the alpine soil seed bank.  

PubMed

Global warming is occurring more rapidly above the treeline than at lower elevations and alpine areas are predicted to experience above average warming in the future. Temperature is a primary factor in stimulating seed germination and regulating changes in seed dormancy status. Thus, plant regeneration from seed will be crucial to the persistence, migration and post disturbance recruitment of alpine plants in future climates. Here, we present the first assessment of the impact of soil warming on germination from the persistent alpine soil seed bank. Contrary to expectations, soil warming lead to reduced overall germination from the soil seed bank. However, germination response to soil temperature was species specific such that total species richness actually increased by nine with soil warming. We further explored the system by assessing the prevalence of seed dormancy and germination response to soil disturbance, the frequency of which is predicted to increase under climate change. Seeds of a significant proportion of species demonstrated physiological dormancy mechanisms and germination of several species appeared to be intrinsically linked to soil disturbance. In addition, we found no evidence of subalpine species and little evidence of exotic weed species in the soil, suggesting that the soil seed bank will not facilitate their invasion of the alpine zone. In conclusion, changes in recruitment via the alpine soil seed bank can be expected under climate change, as a result of altered dormancy alleviation and germination cues. Furthermore, the alpine soil seed bank, and the species richness therein, has the potential to help maintain local species diversity, support species range shift and moderate species dominance. Implications for alpine management and areas for further study are also discussed. PMID:23505066

Hoyle, Gemma L; Venn, Susanna E; Steadman, Kathryn J; Good, Roger B; McAuliffe, Edward J; Williams, Emlyn R; Nicotra, Adrienne B

2013-05-01

181

Frequency signature of water activity by biospeckle laser  

NASA Astrophysics Data System (ADS)

Biospeckle laser technique has become an important tool to investigate biological activity in several areas of science. However, due to the complexity of biological materials it is necessary to develop research processes that ensure greater efficiency in isolating areas of different activities in the same material using the biospeckle. Thus, alternative techniques, such as those related to spectral domain, allow approaches that provide a means for frequency and isolation marking of various observed phenomena. The possibility of creating frequency markers related to physical or chemical phenomena under biospeckle laser monitoring opens the way for important applications in the analysis of biological materials. In seeds, for example, one research challenge is the creation of a methodology to analyze their vigor undermining the influence of water activity. This study aimed to use wavelet transform to create maps in frequency of biological material, particularly from maize and bean seeds, seeking to isolate water activity. Wavelet transform was used in conjunction with traditional biospeckle laser methods, Fujii, Generalized Differences and Time History Speckle Patterns. The data analysis allowed access of information in different frequencies, making it possible to map activities that only occur at certain frequencies in the seeds associated to particular areas they operate, as in the case of activities present in the embryo as well as those present in the endosperm. Thus the work enabled the identification of frequency bands where water activity may be operating creating a signature useful in further works.

Cardoso, Rafael Rodrigues; Costa, Anderson Gomide; Nobre, Cassia Marques Batista; Braga, Roberto Alves

2011-04-01

182

Microwave roasting effects on the oxidative stability of oils and molecular species of triacylglycerols in the kernels of pumpkin ( Cucurbita spp.) seeds  

Microsoft Academic Search

Pumpkin (Cucurbita spp.) seeds of the two cultivars were exposed to microwaves for 6, 12, 20 or 30min at a frequency of 2450MHz using a microwave oven. After the kernels were separated from the whole pumpkin seeds, the quality characteristics and composition of the oils, i.e., their tocopherol distributions and the molecular species of the triacylglycerols (TAGs) were investigated. These

Hiromi Yoshida; Yuka Tomiyama; Yuki Hirakawa; Yoshiyuki Mizushina

2006-01-01

183

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

184

SEEDS: A Celebration of Science  

NASA Technical Reports Server (NTRS)

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

Melton, Bob

1991-01-01

185

The Great Kansas Seed Swindle  

E-print Network

, at 14. Some agents even displayed specimens in glass jars. Id. 2007] THE GREAT KANSAS SEED SWINDLE 989 By 1885 the extent of the financial losses caused by these dishonest plant and tree agents had led both to media coverage and to the involvement...The Great Kansas Seed Swindle MH. Hoeflich' In February, 1885, the Kansas legislature approved a law that made it a misdemeanor punishable by a fine of "not less than ten dollars nor more than two hundred dollars, or by imprisonment in a county jail...

Hoeflich, Michael H.

2007-05-01

186

Native seed preferences of shrub-steppe rodents, birds and ants: the relationships of seed attributes and seed use  

Microsoft Academic Search

Summary This study established the preferences of shrubsteppe granivores among seeds of 6 common sagebrushsteppe plants and related the preferences observed to physical and nutritional attributes of the seeds. Seeds of big sagebrush (Artemisia tridentata), cheatgrass (Bromus tectorum), Indian ricegrass (Oryzopsis hymenoides), western wheatgrass (Pascopyrum smithii), bitterbrush (Purshia tridentata) and green needlegrass (Stipa viridula) were placed in groups of petri

M. I. Kelrick; J. A. MacMahon; R. R. Parmenter; D. V. Sisson

1986-01-01

187

Use Chia Seeds with Caution, Researcher Warns  

MedlinePLUS

... features on this page, please enable JavaScript. Use Chia Seeds With Caution, Researcher Warns Never eat them dry, ... 21, 2014 (HealthDay News) -- Despite potential health benefits, chia seeds may pose a risk if they are not ...

188

Landscape Corridors Provide Pathway for Seed Dispersal  

NSF Publications Database

... Pathway for Seed Dispersal Birds help habitats maintain diversity Seeds were more often found in ... Corridors--narrow strips of habitat that join patches of similar habitat--are thought to provide a ...

189

We're Having a Seed Sale.  

ERIC Educational Resources Information Center

Botany meets computer science in this activity, which challenges students to create a computerized seed catalog. Class members work together to develop a database of plants, much like the major seed companies do. (PR)

Riss, Pam Helfers

1994-01-01

190

SEED-Pro: Computer-Assisted Architectural Programming in SEED  

Microsoft Academic Search

Computer assisted architectural programming is in its infancy. What there is in terms of architectural programming theory often differs from practice. In the first half of this paper, we define relevant terms, provide a brief review of the state of the art, and draw attention to the pri- macy of architectural programming in design. SEED-Pro is introduced as an intelligent

Ömer Akin; Rana Sen; Magd Donia; Ye Zhang

1995-01-01

191

On the relationship between seed-based and ICA-based measures of functional connectivity  

PubMed Central

Brain functional connectivity (FC) refers to inter-regional synchrony of low frequency fluctuations in blood oxygenation level dependent (BOLD) functional MRI (fMRI). FC has been evaluated both during task performance and in the “resting” state, yielding reports of FC differences correlated with behavior and diagnosis. Two methodologies are widely used for evaluating FC from BOLD fMRI data: Temporal correlation with a specified seed voxel or small region of interest; and spatial independent component analysis (ICA). While results from seed-based and ICA methodologies are generally similar, they are conceptually different. The present study is intended to elucidate and illustrate, qualitatively and quantitatively, the relationship between seed and ICA derived measures of FC. Seed-based FC measures are shown to be the sum of ICA-derived within network connectivities and between network connectivities. We present a simple simulation and an experiment on visuomotor activity that highlight this relationship between the two methods. PMID:21394769

Joel, Suresh E; Caffo, Brian S; van Zijl, Peter CM; Pekar, James J

2011-01-01

192

Intercepted Solar Radiation during Seed Filling Determines Sunflower Weight per Seed and Oil Concentration  

Microsoft Academic Search

and on weight per seed. Recently, weight per seed was closely related to intercepted PAR from the end of A reduction in intercepted photosynthetically active radiation flowering (R6 46C d, base temperature 6C) to (PAR) during a short period of seed filling could affect weight per seed physiological maturity (R9, Schneiter and Miller, 1981) and oil concentration in sunflower (Helianthus

Luis A. N. Aguirrezábal; Yorick Lavaud; Guillermo A. A. Dosio; Natalia G. Izquierdo; Fernando H. Andrade; Leila M. González

2003-01-01

193

The effects of seed abundance on seed predation and dispersal by rodents in Castanopsis fargesii (Fagaceae)  

Microsoft Academic Search

Based on the animal dispersal hypothesis and the predator satiation hypothesis, we examined the effects of seed abundance at both population (i.e., mast seeding) and community levels on seed predation and dispersal of Castanopsis fargesii (Fagaceae), a rodent-dispersed mast species in Eastern Asia. In a subtropical evergreen broadleaved forest in the Dujiangyan region of Sichuan Province, China, individual seeds with

Zhishu Xiao; Zhibin Zhang; Yushan Wang

2005-01-01

194

ORIGINAL PAPER Internal dispersal of seeds by waterfowl: effect of seed size  

E-print Network

for plant species that do not produce fleshy fruits. Seed mass is assumed to have evolved as a compromise of seed shadows produced by vertebrates depend both on movement patterns of the dispersers germination can modify the seed shadows produced by birds due to higher percent germination of seeds retained

Green, Andy J.

195

Another Wintertime Cloud Seeding Case Study with Strong Evidence of Seeding Effects  

Microsoft Academic Search

In the 1990s numerous winter orographic cloud seeding experiments were conducted over Utah's Wasatch Plateau. Several previously published case studies suc- cessfully documented the physical response in clouds and precipitation to ground-based seeding with silver iodide and liquid propane. A previously unpublished case study that shows additional evidence of positive seeding effects is presented here. Careful docu- mentation of seeding

Arlen W. Huggins

196

Seed Disperser Effectiveness: The Quantity Component and Patterns of Seed Rain for Prunus mahaleb  

Microsoft Academic Search

In this paper we analyze the seed dispersal stage of the Prunus mahaleb-frugivorous bird inter- action from fruit removal through seed delivery within the context of disperser effectiveness. The effectiveness of a frugivorous species as a seed disperser is the contribution it makes to plant fitness. Effectiveness depends on the quantity of seed dispersed (''quantity component'') and the quality of

Pedro Jordano; Eugene W. Schupp

2000-01-01

197

Mechanical damage to soybean seed during processing  

Microsoft Academic Search

The effects of seed cleaning and handling on soybean seed germination and physical integrity were determined with changing seed moisture content (m.c.). In addition, storage behavior of seed and loss of storability caused by damage resulting from free-fall from different heights were determined.Six lots of the variety “MACS-13” at three different m.c.'s were passed through a vertical bucket elevator, cleaner

Shreekant R. Parde; Rameshwar T. Kausal; Digvir S. Jayas; Noel D. G. White

2002-01-01

198

Rangeland Risk Management for Texans: Seeding Rangeland  

E-print Network

and trees such as Kudzu, Chinese tal- lowtree, kochia, Korean lespedeza, yellow sweetclover, Russian olive, lantana and salt cedar. 6) Planting method. Because it is important that seeds have good contact with the soil, drilling seed is the most successful... and trees such as Kudzu, Chinese tal- lowtree, kochia, Korean lespedeza, yellow sweetclover, Russian olive, lantana and salt cedar. 6) Planting method. Because it is important that seeds have good contact with the soil, drilling seed is the most successful...

Rector, Barron S.

2000-11-01

199

Monitoring soybean seed germination by calorimetry  

Microsoft Academic Search

A method to monitor seed germination that combines isothermal calorimetry and imbibition measurements is reported. Individual\\u000a seeds of three cultivars of soybean seeds (A7636RG, Munasqa and DM5.8RR) and one of radish were used. Imbibition curves were\\u000a performed on individual seeds in a germination chamber at 25 °C. Calorimetric specific thermal power (p)–time (t) curves of germination were also obtained at 25 °C

Fanny I. Schabes; E. Elizabeth Sigstad

2011-01-01

200

An XUV-FEL amplifier seeded using high harmonic generation  

NASA Astrophysics Data System (ADS)

A detailed design of a free electron laser (FEL) amplifier operating in the extreme ultra violet (XUV) and seeded directly by a high harmonic source is presented. The design is part of the 4th generation light source (4GLS) facility proposed for the Daresbury Laboratory in the UK which will offer users a suite of high brightness synchronised sources from THz frequencies into the XUV. The XUV-FEL will generate photons with tunable energies from 8 to 100 eV at giga-watt peak power levels in near Fourier-transform limited pulses of variable polarisation. The designs of the high harmonic generation (HHG) seeding, FEL amplifier and synchronising systems are presented. Numerical simulations quantify the FEL output characteristics.

McNeil, B. W. J.; Clarke, J. A.; Dunning, D. J.; Hirst, G. J.; Owen, H. L.; Thompson, N. R.; Sheehy, B.; Williams, P. H.

2007-04-01

201

Unsupervised frequency selection†  

Microsoft Academic Search

The paper describes an algorithm for the unsupervised selection of frequencies for Bode or Nyquist frequency analyses. The algorithm includes phase crossovers, gain crossovers, bounds on the frequency range, critical points, and a multiplicative increment.

RICHARD A. NORTHOUSE

1972-01-01

202

HIV Testing Frequency  

MedlinePLUS

... HIV Testing Frequency Translate Text Size Print Share HIV Testing Frequency Testing Frequency How often should you ... local health department for proper care and information. HIV Testing HIV Test Locations HIV Test Types HIV ...

203

Fat but slim: Criteria of seed attractiveness for earthworms  

Microsoft Academic Search

Earthworms were shown to significantly affect seeds and seedlings survival via their ingestion and digestion for nutritive purposes. Such selective feeding of earthworms on plant seeds is likely to favour certain plant species and to affect seed bank composition, plant recruitment and plant community structure. Relationships between earthworms and seeds, particularly seed traits that determine attractiveness of seeds for earthworms,

Julia Clause; Pierre Margerie; Estelle Langlois; Thibaud Decaëns; Estelle Forey

204

Abscisic acid and assimilate partitioning during seed development  

Microsoft Academic Search

This thesis describes the influence of abscisic acid (ABA) on the transport of assimilates to seeds and the deposition of reserves in seeds. It is well-known from literature that ABA accumulates in seeds during development, and that ABA concentrations in seeds correlate rather well with seed size and seed growth rates. However, since ABA is at least partly synthesized in

Bruijn de S. M

1993-01-01

205

Characteristics and composition of different seed oils and flours  

Microsoft Academic Search

The nutritional quality and functional properties of paprika seed flour and seed kernel flours of pumpkin and watermelon, and also the characteristics and structure of their seed oils, were studied. Paprika seed and seed kernels of pumpkin and watermelon were rich in oil and protein. All flour samples contained considerable amounts of P, K, Mg, Mn and Ca. Paprika seed

Tarek A El-Adawy; Khaled M Taha

2001-01-01

206

Applications of Computers in Seed Technology  

Microsoft Academic Search

Seed vigor testing provides valuable information for assessing seed lot quality. However, vigor testing has not experienced widespread use because it is labor intensive, high in cost, and test results are often variable from laboratory to laboratory. An automated seed vigor assessment system is presented for lettuce (Lactuca sativa L.) and soybeans (Glycine max (L.) Merr.) that is objective, economical,

Y. Sako; A. Hoffmaster; K. Fujimura; M. B. McDonald; M. A. Bennett

207

Aspen Seed Collection Nursery Information Series  

E-print Network

color of the male anthers that catch one's eye. Male flowers Seem to emerge earlier in the season than pistil or capsule from female flower. Color can be deceptive and helpful both. Red or maroon color be determined. Close examination of the seed is a must. Seed maturity is best determined by seed color. Early

208

Plant Populations and Seeding Rates for Soybeans  

E-print Network

Plant Populations and Seeding Rates for Soybeans Andrew P. Robinson Department of Agronomy www input costs for soybean growers, so it's important for growers to plant the right amount of seed to minimize input costs and increase profitability. Seeding rate, plant population, and row spacing are tied

Holland, Jeffrey

209

Some engineering properties of locust bean seed  

Microsoft Academic Search

Locust bean was found to be a protein rich crop whose seed is processed into local food condiment ‘iru’ in Nigeria. To explore the possibility of developing handling and processing equipment for the seed, some engineering properties namely: size, 1000 seed weight, true density, bulk density, porosity, static coefficient of friction on wood, angle of repose, specific heat and cracking

L. A. O. Ogunjimi; N. A. Aviara; O. A. Aregbesola

2002-01-01

210

WEATHER MODIFICATION BY AIRCRAFT CLOUD SEEDING  

E-print Network

WEATHER MODIFICATION BY AIRCRAFT CLOUD SEEDING BERYULEV G.P. Head, Department of Cloud;#12; Precipitation Enhancement An aircraft cloud seeding by iceforming or hygroscopic agents is a basis of atmosphere and clouds necessary for decision making, fulfillment of seeding and assessment

Vali, Gabor

211

Field Test of Combination Seeding Flares  

E-print Network

2008 during the Polarimetric Cloud Analysis and Seeding Test 2 (POLCAST2) field project. Aircraft for cloud seeding and airborne measurements. For the 1 July 2008 flight, the Cessna 340 aircraft's flareField Test of Combination Seeding Flares Report to Ice Crystal Engineering 5985 49th St. SE

Delene, David J.

212

Polarimetric Cloud Analysis and Seeding Test 3  

E-print Network

Polarimetric Cloud Analysis and Seeding Test 3: Cloud Micro-physical Data Analysis David Delene;Motivation The Polarimetric Cloud Analysis and Seeding Test 3 (POLCAST3) experiment is a continuation Objectives Characterization of hygroscopic seeding effects stratified by aerosol and Cloud Condensation

Delene, David J.

213

The poppy seed defense: a novel solution.  

PubMed

A major toxicological challenge is distinguishing whether morphine in urine, in the absence of 6-monoacetylmorphine (6-MAM), originates from 'street' heroin use or poppy seed ingestion. Manufacturing byproducts from the synthesis of illicit heroin include those that originate from the reaction of acetic anhydride with the alkaloid impurity, thebaine, which undergoes skeletal rearrangement, resulting in compounds with a 2-(N-methylacetamido)ethyl side-chain. The hypothesis that the tertiary amide in this side-chain is resistant to endogenous hydrolysis was supported from in-vitro experiments; a glucuronide metabolite (designated 'ATM4G') was identified that may be used as a marker of 'street' heroin administration. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for this metabolite was then performed on selected urine specimens from 22 known heroin users, these being negative on routine testing for 6-MAM by gas chromatography-mass spectrometry (GC-MS), using the generally applied reporting threshold of 10?ng/mL, but positive for the presence of morphine. Peaks corresponding to the retention time for the metabolite marker were clearly observed for 16 of the 22 samples, with variations of the ratios of its three dependent ions being within?±?30% of that produced in vitro. Conversely, 6-MAM was detected in only 3 samples, but at concentrations <1?ng/mL. Such a high frequency for the presence of the metabolite marker in urine, in the absence of 6-MAM, is noteworthy and suggests that detection of this metabolite may offer an important advance in forensic toxicology, allowing the development of a new and more definitive test for heroin abuse and thus a potential solution to the so-called 'poppy seed defense'. PMID:24339374

Chen, P; Braithwaite, R A; George, C; Hylands, P J; Parkin, M C; Smith, N W; Kicman, A T

2014-03-01

214

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

215

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.

216

Seed coat structure and dormancy  

Microsoft Academic Search

An understanding of dormancy mechanisms is of ecological and economic importance. Identification of the level at which dormancy is imposed appears to be species specific. The variation brought about by this therefore requires that developmental studies be included in seed coat dormancy experiments. In most cases, a site of permeability can be identified during the developmental process, and this information

K. M. Kelly; J. Staden; W. E. Bell

1992-01-01

217

ANTIOXIDANT ACTIVITIES OF LUPIN SEEDS  

Microsoft Academic Search

Lupin seeds have been used as a source of protein for animal feeding and human consumption. Recently, human consumption of lupins has been increased due to their nutritional values and some functional properties. As lupins are used as an ingredient in foods, the health benefits of lupins are being investigated by researchers. It was known that antioxidant phytochemicals in foods

Shaofang Wang; Jon Clements

218

Withanolides from hyoscyamus niger seeds  

PubMed

Three withanolide class steroids were isolated from the seeds of Hyoscyamus niger. Two of them were identified as daturalactone-4 (1) and Nic-3 (which is now named hyoscyamilactol) (2). The new compound was elucidated as 16alpha-acetoxyhyoscyamilactol (3) on the basis of spectroscopic properties and X-ray crystallographic analysis. PMID:10543915

Ma; Williams; Che

1999-10-01

219

Strangelet seeding from stellar evolution  

Microsoft Academic Search

The authors present a scenario for strangelets seeding in galactic environments based on the ejection of strange matter from type II super nova events. The possibility that these aggregates act in turn as triggers of future explosions of the same type is discussed, together with the expected features of their distribution and abundance.

O. G. Benvenuto; J. E. Horvath

1989-01-01

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

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

222

Two-phase seed dispersal: linking the effects of frugivorous birds and seed-caching rodents  

Microsoft Academic Search

Frugivorous birds disperse the seeds of many fruit-bearing plants, but the fate of seeds after defecation or regurgitation\\u000a is often unknown. Some rodents gather and scatter hoard seeds, and some of these may be overlooked, germinate, and establish\\u000a plants. We show that these two disparate modes of seed dispersal are linked in some plants. Rodents removed large (>25 mg)\\u000a seeds from

Stephen B. Vander Wall; Kellie M. Kuhn; Jennifer R. Gworek

2005-01-01

223

[Seed rain, soil seed bank, and natural regeneration of natural Toona ciliata var. pubescens forest].  

PubMed

Taking the natural Toona ciliata var. pubescens forest in the Jiujiangshan National Nature Reserve in Jiangxi Province of China as test object, an investigation was conducted on the seed rain, soil seed bank, and seedlings number in 2008-2011. The seed rain of the forest was dispersed from late October to the end of December. In 2010, the seed rain intensity in different sampling plots was in the order of Xiagongtang observatory (320.3 +/- 23.5 seeds x m(-2)) > Xiagongtang protection station (284.7 +/- 24.2 seeds x m(-2)) > Daqiutian protection station (251.6 +/- 24.7 seeds x m(-2)), and the quantity of the intact seeds in soil supplied for seed germination and regeneration was 222.0, 34.3, and 22.6 seeds x m(-2), respectively. The seed bank reserves was affected by the seed production amount, bird feeding, and seed viability, etc., of which, bird feeding was the prime factor for the substantial drop of the seed bank reserves. Due to the low resistance against storage and a large number of rot during storage, the seeds in soil could hardly be effectively stored beyond one month. The seedlings germinated in December were averagely less than 2 stands x m(-2), and the soil seed reserves in the next January was the least (6.7-11.8 seeds x m(-2)), with the germinated seedlings averagely 0.4-0.6 stands x m(-2), which was consistent with the rare distribution of natural seedlings in the forest. It was concluded that the small seed rain reserves, low seed vigor of soil seed bank, and low seedling establishment were the important factors impacting the natural regeneration of T. ciliata var. pubescens. PMID:22803462

Huang, Hong-Lan; Zhang, Lu; Liao, Cheng-Kai

2012-04-01

224

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

225

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

226

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

227

Experimental and Numerical Investigation of Single Frequency Amplifier with Photonic Bandgap Fiber at 1178 nm  

NASA Astrophysics Data System (ADS)

A single frequency photonic bandgap fiber amplifier at 1178 nm is investigated experimentally and numerically. With a pump power of 81 W, a single frequency 1178 nm fiber laser of 10.3 W is obtained with a 3W seed laser and a 20 m gain fiber. Numerical simulation is conducted with a rate equation model taking amplified spontaneous emission and stimulated Brillouin scattering (SBS) into consideration. Temperature distribution along the fiber is applied for SBS suppression, more than 50 W single frequency fiber laser at 1178 nm is predicted theoretically with a 5W seed laser and a 40 m long gain fiber with five temperature steps.

Wang, Jian-Hua; Cui, Shu-Zhen; Hu, Jin-Meng; Cao, Fen; Fang, Yong; Lu, Hui-Ling

2014-06-01

228

Improved efficiency of somatic embryogenesis from zygotic embryos in Hyoscyamus niger by seed water-soaking  

Microsoft Academic Search

We describe an efficient procedure to obtain somatic embryos from mature zygotic embryos of Hyoscyamus niger (black henbane). It has several advantages over previous regeneration methods, which are: the use of mature seeds, an average 80% somatic embryogenesis rate and a high (eight-fold higher than the control) plant regeneration frequency. The critical step in this protocol was soaking of the

Shanjun Tu; R. S. Sangwan; B. S. Sangwan-Norreel

2005-01-01

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

In vitro seed to seed growth on clinostats  

NASA Technical Reports Server (NTRS)

The effect of a long term micro-gravity environment on the life cycle of plants is unknown. Whether higher plants have evolved to a stage where removal or reduction of gravity is detrimental to plant life cycle and thus fatal to the plant species, is an unanswered question in space plants which were successfully grown through the various stages of their life cycle. Attempts to grow plants as a continuous integral process from seed to seed through one generation were successful until recently. Culture of plants through multiple generations was not accomplished in space nor in ground based studies. The effect of long term simulated weightlessness by growing consecutive generations of plants continuously on clinostats using the cruciferous plants, Arabidopsis thaliana (L.) Heyn. and Cardamine oligosperma Nutt. is being investigated.

Hoshizaki, T.

1984-01-01

231

Frequency Measurement & Analysis Service  

E-print Network

NIST Frequency Measurement & Analysis Service #12;A Complete Solution To All Frequency Measurement & Calibration Problems The NIST Frequency Measurement and Analysis Service makes it easy to measure and calibrate any quartz, rubidium, or cesium frequency standard. All measurements are made automatically

Magee, Joseph W.

232

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

233

Seed physiological maturity in Cuphea  

Microsoft Academic Search

Cuphea (Cuphea viscosissima Jacq.×C. lanceolata f. silenoides W.T. Aiton, line PSR23) is a new crop being developed in the North Central United States, as an industrial oilseed crop. Cuphea PSR23 seed oil is rich in medium-chain-length fatty acids such as capric acid used to manufacture soaps and detergents. The objective of this research was to determine the time when physiological

Marisol T. Berti; Burton L. Johnson; Linda K. Manthey

2007-01-01

234

Precision metering of germinated seeds  

E-print Network

viability test and analysis. 208 LIST OF FIGURES Figure Graphical representations of the two-parameter exponential distribution. Page 31 Final seed metering system design. Major parts of overall control system. 50 52 Schematic of the single file... for metering system tests. 151 26 27 28 29 30 31 Histograms of arrival time c. o. v. Histograms of arrival time skewness Histograms of arrival time kurtosis. Arrival time density functions. Histogram of TMPTM/TMER for run 7. Scatter plot of percent...

Elliot, Gregory Lawrence

2012-06-07

235

MHD seed recovery and regeneration  

NASA Astrophysics Data System (ADS)

The TRW Econoseed MHD Seed Regeneration Process is based on the reaction of calcium formate with potassium sulfate spent seed from an MHD electric power generation plant. The process was tested at bench scale, design a proof of concept (POC) test plant, plan and cost a Phase 2 project for a POC plant evaluation and prepare a conceptual design of a 300 MW (t) commercial plant. The results of the project are as follows: (1) each of the unit operations is demonstrated, and (2) the data are incorporated into a POC plant design and project cost, as well as a 300 MW (t) commercial retrofit plant design and cost estimate. Specific results are as follows: (1) calcium formate can be produced at 100 percent yield in a total retention time of less than 5 minutes, (2) utilizing the calcium formate, spent seed can quantitatively be converted to potassium formate, potassium carbonate or mixtures of these with potassium sulfate as per the commercial design without measurable loss of potassium to insolubles at a total retention time under 20 minutes and ambient pressure, (3) the solid rejects form the process meet RCRA EP Toxicity requirements for safe disposal, and (4) filtration and evaporation data, as well as reaction data cited above, show that the Econoseed technology is ready for scale up to POC plant scale. Economics forecast studies show that the total cost per unit of potassium for seed regeneration by the Econoseed Process is in the range of $0.23 to $0.27/lb, a cost which is less than half the potassium cost of $0.63/lb for purchasing new potassium carbonate.

1988-10-01

236

Seed oil of Artemisia absinthium  

Microsoft Academic Search

The oil of the seeds ofArtemisia absinthium has yielded 95.5% of glycerides. Of these, 59.5% consists of unoxidized and 32.0% of oxidized triglycerides, 1.3% of diglycerides,\\u000a and 2.7% of monoglycerides. The remaining 4.5% of the oil is made up of hydrocarbons, sterols, sterol acetates, and free fatty\\u000a acids. The oxy acid content has been calculated from the results obtained (?12%

N. T. Ul'chenko; É. I. Gigienova; K. L. Seitanidi; M. R. Yagudaev; A. U. Umarov

1979-01-01

237

Lipids of Viburnum opulus seeds  

Microsoft Academic Search

Lipid components of the seeds ofViburnum opulus (Caprifoliaceae family) were investigated. The neutral lipids consist of eight classes, the glycolipids consist of three classes, and the\\u000a phospholipids contain seven classes. The fatty-acid contents of all of the acyl-containing lipids were determined. The 18?2\\u000a fatty acid is the main component of all the lipid fractions. The content of saturated acids is

S. G. Yunusova; E. G. Zinurova; M. S. Yunusov; E. G. Galkin; A. R. Karimova

1998-01-01

238

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

239

Occurrence and distribution of tomato seed-borne mycoflora in Saudi Arabia and its correlation with the climatic variables.  

PubMed

One hundred samples of tomato seeds were collected in 2011 and 2012 from tomato-cultivated fields in Saudi Arabia and screened for their seed-borne mycoflora. A total of 30 genera and 57 species of fungi were recovered from the collected seed samples using agar plate and deep-freezing blotter methods. The two methods differed as regards the frequency of recovered seed-borne fungi. Seven fungi among those recovered from tomato seeds, which are known as plant pathogens, were tested for their pathogenicity and transmission on tomato seedlings. The recovery rate of these pathogens gradually decreased from root up to the upper stem, and did not reach to the stem apex. The distribution of tomato seed-borne fungi was also investigated throughout Saudi Arabia. In this concern, Al-Madena governorate recorded the highest incidence of fungal flora associated with tomato seeds. The impact of meteorological variables on the distribution of tomato seed-borne mycoflora was explored using the ordination technique (canonical correspondence analysis). Among all climatic factors, relative humidity was the most influential variable in this regard. Our findings may provide a valuable contribution to our understanding of future global disease change and may be used also to predict disease occurrence and fungal transfer to new uninfected areas. PMID:24964218

Al-Askar, Abdulaziz A; Ghoneem, Khalid M; Rashad, Younes M; Abdulkhair, Waleed M; Hafez, Elsayed E; Shabana, Yasser M; Baka, Zakaria A

2014-11-01

240

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. PMID:23671651

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

241

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. PMID:23847647

He, Dongli; Yang, Pingfang

2013-01-01

242

MHD seed recovery/regeneration  

NASA Astrophysics Data System (ADS)

Task 1 calls for the design, procurement, construction, and installation of the Seed Regeneration Proof-of-Concept Facility (SRPF) that will produce tonnage quantities of recyclable potassium formate seed at a design rate of 250 lb/hr for testing in the channel at the CDIF while collecting data that will be used to upgrade the design of a 300 MW(sub t) system. Approximately 12 tons of KCOOH (dry basis) as 70-75 wt percent solution were produced. The front end of the plant (potassium sulfate reaction and solids separation/washing units) was operated for five days in March. Most of the operations were conducted at a spent seed feed rate of 250 pounds/hour. A total of 8,500 gallons of dilute KCOOH solution was generated containing approximately 2.6 tons of potassium formate (dry basis). The average KCOOH content of this solution was 7 wt percent. The design KCOOH solution concentration for the front end of the plant is 8.5 wt percent. The evaporation unit was operated for a total of six days during March. Approximately 2.5 tons of potassium formate (dry basis) were processed through the evaporator and concentrated to greater then 7 wt percent.

243

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

244

Local Evolution of Seed Flotation in Arabidopsis  

PubMed Central

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; Salle, Christine; Poulain, Damien; Granier, Fabienne; Botran, Lucy; Loudet, Olivier; de Meaux, Juliette; Marion-Poll, Annie; North, Helen M.

2014-01-01

245

Slippage effect on laser phase error amplification in seeded harmonic generation free-electron lasers  

E-print Network

Free-electron lasers (FELs) seeded with external lasers hold great promise for generating high power radiation with nearly transform-limited bandwidth in soft x-ray region. However, it has been pointed out that the initial seed laser noise 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 for laser phase error 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 laser pulse length. This smoothing effect allows one to preserve the excellent temporal coherence of seeded FELs in presence of large laser phase errors. For ultra-short UV seed lasers with FWHM around 16 fs, the slippage length in a modulator with ~30 undulator periods i...

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

2013-01-01

246

When will plant morphology affect the shape of a seed dispersal "kernel"?  

PubMed

Most models of dispersal assume that plants are point sources. In reality, the scale in height over which seed sources are distributed is often of the same order as the scale in distance over which most individual seeds are dispersed. But is this sufficient to affect the fundamental shapes of dispersal frequency distributions? Most published conclusions about the effects of canopy structure on dispersal are subjective. A model is developed to explore the consequences of plant canopies for the shapes of whole-plant seed dispersal "kernels". The canopies were described by simple geometric shapes, while an empirical probability density function (PDF) was used for dispersal from a point source. It was found that the resulting whole-plant PDF for dispersal distance was almost invariably peaked, whereas the PDF for the density of seed rain (as would be measured by pitfall traps) could either be peaked or monotonic according to the canopy shape, position of seeds in the canopy, and mean dispersal distance. The shapes of kernels from whole plants (distributed seed sources) can be very different from those derived from a point source under certain circumstances. PMID:11444954

Cousens, R D; Rawlinson, A A

2001-08-01

247

Parasitoid attack of the seed-feeding beetle Bruchus loti enhances the germination success of Lathyrus japonicus seeds  

Microsoft Academic Search

Hard seeds of some legume species can germinate after seed-feeding insects bore through the seed coat and consequently break\\u000a seed dormancy. Larvae of bruchine beetles are the main seed feeders attacking many legume species. Boring of the hard seed\\u000a coat by bruchine beetle larvae enhances the germination percentage of legume species, but consuming too much of a single seed\\u000a may

Zenta NakaiTetsuya; Tetsuya Kondo; Shin-ichi Akimoto

248

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

249

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

NASA Astrophysics Data System (ADS)

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

2011-07-01

250

Seed size as an indicator of seed quality: a case study of Primula veris  

NASA Astrophysics Data System (ADS)

Seed size is a widely accepted measure of seed quality, because many earlier studies have shown that large seeds have high seedling survival, growth and establishment. We tested whether ovule loss increases size of the remaining seeds and whether such size increase affects seedling establishment. We removed all except one flower from inflorescences of Primula veris L. (Primulaceae), a perennial hemicryptophyte herb, at a late stage of flowering. Flower removal (FR) increased seed size by 33% compared to the control plants. We then divided the seeds within each treatment to small, middle-sized and large seeds and carried out a sowing experiment in the field. Within each experimental group, seedling establishment was positively associated with seed size. However, despite size differences, seeds from the FR and control groups had the same seedling establishment probability. Seeds from FR plants had a higher seedling emergence in May than those from control plants, but the number of seedlings alive per sowing plot in the late summer was the same in both experimental groups. Increase in seed mass after partial FR thus did not enhance seedling performance, although seed size variation due to other causes was positively correlated with seedling establishment. Further studies are needed to show whether plastic changes of seed size are usually adaptive or not.

Lehtilä, Kari; Ehrlén, Johan

2005-11-01

251

Yellowstone grizzly bear mortality, human habituation, and whitebark pine seed crops  

USGS Publications Warehouse

The Yellowstone grizzly bear (Ursus arctos horribilis) population may be extirpated during the next 100-200 years unless mortality rates stabilize and remain at acceptable low levels. Consequently, we analyzed relationships between Yellowstone grizzly bear mortality and frequency of human habituation among bears and size of the whitebark pine (Pinus albicaulis) seed crop. During years of large seed crops, bears used areas within 5 km of roads and 8 km of developments half as intensively as during years of small seed crops because whitebark pine's high elevation distribution is typically remote from human facilities. On average, management trappings of bears were 6.2 times higher, mortality of adult females 2.3 times higher, and mortality of subadult males 3.3 times higher during years of small seed crops. We hypothesize that high mortality of adult females and subadult males during small seed crop years was a consequence of their tendency to range closest (of all sex-age cohorts) to human facilities; they also had a higher frequency of human habituation compared with adult males. We also hypothesize that low morality among subadult females during small seed crop years was a result of fewer energetic stressors compared with adult females and greater familiarity with their range compared with subadult males; mortality was low even though they ranged close to humans and exhibited a high frequency of human habituation. Human-habituated and food-conditioned bears were 2.9 times as likely to range within 4 km of developments and 3.1 times as often killed by humans compared with nonhabituated bears. We argue that destruction of habituated bears that use native foods near humans results in a decline in the overall ability of bears to use available habitat; and that the number and extent of human facilities in occupied grizzly bear habitat needs to be minimized unless habituated bears are preserved and successful ways to manage the associated risks to humans are developed.

Mattson, David J.; Blanchard, Bonnie M.; Knight, Richard R.

1992-01-01

252

Oxidative signaling in seed germination and dormancy  

PubMed Central

Reactive Oxygen Species (ROS) play a key role in various events of seed life. In orthodox seeds, ROS are produced from embryogenesis to germination, i.e., in metabolically active cells, but also in quiescent dry tissues during after ripening and storage, owing various mechanisms depending on the seed moisture content. Although ROS have been up to now widely considered as detrimental to seeds, recent advances in plant physiology signaling pathways has lead to reconsider their role. ROS accumulation can therefore be also beneficial for seed germination and seedling growth by regulating cellular growth, ensuring a protection against pathogens or controlling the cell redox status. ROS probably also act as a positive signal in seed dormancy release. They interact with abscisic acid and gibberellins transduction pathway and are likely to control numerous transcription factors and properties of specific protein through their carbonylation. PMID:19513212

El-Maarouf-Bouteau, Hayat

2008-01-01

253

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

254

Evolutionary Ecology, 1994, 8, 188-195 Pollen availability, seed production and seed  

E-print Network

, Cirsium arvense. Offspring of flies feed solelyon thistle seeds and seed production is pollen- limited thistle (Cirsium arvense) may be affected by the availability of pollen. In Europe, O. ruficauda attacks

Lalonde, Bob

255

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.

256

Evolutionary Dynamics of Seed Size and Seedling Competitive Ability  

Microsoft Academic Search

We present a model for the evolutionary dynamics of seed size when there is a trade-off between seed size and seed number, and seedlings from large seeds are better competitors and have a higher precompetitive survival than seedlings from small seeds. We find that strong competitive asymmetry, high resource levels, and intermediate harshness of the precompetitive environment favor coexistence of

Stefan A. H. Geritz; Ed van der Meijden; Johan A. J. Metz

1999-01-01

257

Tansley review Seed dormancy and the control of germination  

E-print Network

Tansley review Seed dormancy and the control of germination William E. Finch-Savage1 and Gerhard This section on applied aspects of the control of seed germination by dormancy is an additional part the seed at the molecular level? 5. Applied aspects of the control of germination by seed dormancy Seeds

Leubner, Gerhard

258

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

259

Choosing the best heuristic for seeded alignment of DNA sequences  

Microsoft Academic Search

Background: Seeded alignment is an important component of algorithms for fast, large-scale DNA similarity search. A good seed matching heuristic can reduce the execution time of genomic- scale sequence comparison without degrading sensitivity. Recently, many types of seed have been proposed to improve on the performance of traditional contiguous seeds as used in, e.g., NCBI BLASTN. Choosing among these seed

Yanni Sun; Jeremy Buhler

2006-01-01

260

Seed size and quantitative characters in Avena barbata  

Microsoft Academic Search

Seed-size differences in Avena barbata Pott ex Link are of two sorts. First, there is a seed-size dimorphism (floret position) such that half of the seeds on every plant are larger. Second, the characteristic seed sizes of certain populations are significantly larger than those of other populations. This study reports relationships between seed size and quantitative characters at very early,

Elmarie S Hutchinson

1984-01-01

261

Generalized frequency modulation  

E-print Network

In frequency modulation (FM) systems, a continuous-time information signal is modulated onto a sinusoidal carrier wave by using the information signal to modulate the frequency of the carrier wave. In this thesis, a more ...

Torres, Wade Patrick

2001-01-01

262

Frequency comb swept lasers  

E-print Network

We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep ...

Tsai, Tsung-Han

263

Seed Total Phosphate and Phytic Acid  

Microsoft Academic Search

Both the total amount and composition of seed phosphorus (P) are important to maize end-use quality. Seed total P represents\\u000a a major pool in the flux of P through the agricultural ecology. The phosphate stored in seeds of major crops represents a\\u000a sum equivalent to more than 50% of phosphate fertilizer applied annually worldwide (Lott et al. 2000). Clearly this

Victor Raboy

264

Photoacoustic imaging of prostate brachytherapy seeds.  

PubMed

Brachytherapy seed therapy is an increasingly common way to treat prostate cancer through localized radiation. The current standard of care relies on transrectal ultrasound (TRUS) for imaging guidance during the seed placement procedure. As visualization of individual metallic seeds tends to be difficult or inaccurate under TRUS guidance, guide needles are generally tracked to infer seed placement. In an effort to improve seed visualization and placement accuracy, the use of photoacoustic (PA) imaging, which is highly sensitive to metallic objects in soft tissue, was investigated for this clinical application. The PA imaging properties of bare (i.e., embedded in pure gelatin) and tissue-embedded (at depths of up to 13 mm) seeds were investigated with a multi-wavelength (750 to 1090 nm) PA imaging technique. Results indicate that, much like ultrasonic (US) imaging, an angular dependence (i.e., seed orientation relative to imaging transducer) of the PA signal exists. Despite this shortcoming, however, PA imaging offers improved contrast, over US imaging, of a seed in prostate tissue if sufficient local fluence is achieved. Additionally, although the PA signal of a bare seed is greatest for lower laser wavelengths (e.g., 750 nm), the scattering that results from tissue tends to favor the use of higher wavelengths (e.g., 1064 nm, which is the primary wavelength of Nd:YAG lasers) when the seed is located in tissue. A combined PA and US imaging approach (i.e., PAUS imaging) shows strong potential to visualize both the seed and the surrounding anatomical environment of the prostate during brachytherapy seed placement procedures. PMID:21833361

Su, Jimmy L; Bouchard, Richard R; Karpiouk, Andrei B; Hazle, John D; Emelianov, Stanislav Y

2011-08-01

265

Seeding of high temperature air flow  

Microsoft Academic Search

Seeding of high temperature air flows is problematic because common seeding materials can ignite and may pose a threat for\\u000a human health in case of inhalation. Sodium chloride is proposed as a seeding material to avoid these problems. The generation\\u000a of crystals using an ultrasonic atomizer is described and the measured particle size distribution is presented. The described\\u000a method has

D. Rusch; A. Kempe; T. Roesgen

2007-01-01

266

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

267

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

268

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

269

The restoration of sedge meadows: seed viability, seed germination requirements, and seedling growth of Carex species  

Microsoft Academic Search

To better understand how to establishCarex species from seed in created and restored wetlands, a series of experimental studies was conducted onCarex seed and seedlings. These studies included (1) the effect of seed age (1 to 18 months after collection) on viability and\\u000a germination, (2) storage conditions (+4,-4 or +4\\/-4°C; wet or dry) on seed germination, (3) soil moisture on

Arnold G. van der Valk; Tony L. Bremholm; Elizabeth Gordon

1999-01-01

270

Effect of Noise on the Mathematical Parameters that Describe Isothermal Seed Germination.  

PubMed

A mathematical model is proposed to describe the isothermal germination rate of seeds as a function of time. All environmental parameters were held constant with the exception of the sound-pressure level and the frequency of the impinging sound waves. Each single frequency sound has its own set of mathematical parameters that describe the differential germination rate as a function of time. Frequencies of 100, 1000, 2000, 4000, and 9000 hertz as well as broad band noise, all at 100 decibels, were used in the experiments. PMID:16658758

Hageseth, G T

1974-04-01

271

Proteopathic tau seeding predicts tauopathy in vivo.  

PubMed

Transcellular propagation of protein aggregates, or proteopathic seeds, may drive the progression of neurodegenerative diseases in a prion-like manner. In tauopathies such as Alzheimer's disease, this model predicts that tau seeds propagate pathology through the brain via cell-cell transfer in neural networks. The critical role of tau seeding activity is untested, however. It is unknown whether seeding anticipates and correlates with subsequent development of pathology as predicted for a causal agent. One major limitation has been the lack of a robust assay to measure proteopathic seeding activity in biological specimens. We engineered an ultrasensitive, specific, and facile FRET-based flow cytometry biosensor assay based on expression of tau or synuclein fusions to CFP and YFP, and confirmed its sensitivity and specificity to tau (?300 fM) and synuclein (?300 pM) fibrils. This assay readily discriminates Alzheimer's disease vs. Huntington's disease and aged control brains. We then carried out a detailed time-course study in P301S tauopathy mice, comparing seeding activity versus histological markers of tau pathology, including MC1, AT8, PG5, and Thioflavin S. We detected robust seeding activity at 1.5 mo, >1 mo before the earliest histopathological stain. Proteopathic tau seeding is thus an early and robust marker of tauopathy, suggesting a proximal role for tau seeds in neurodegeneration. PMID:25261551

Holmes, Brandon B; Furman, Jennifer L; Mahan, Thomas E; Yamasaki, Tritia R; Mirbaha, Hilda; Eades, William C; Belaygorod, Larisa; Cairns, Nigel J; Holtzman, David M; Diamond, Marc I

2014-10-14

272

Physicochemical and grinding characteristics of dragonhead seeds  

NASA Astrophysics Data System (ADS)

The results of investigations on the physicochemical and grinding characteristics of Moldavian dragonhead seeds are presented. The data obtained showed that the physical properties (average size, sphericity, surface area, 1 000 seed mass, dynamic angle of repose, coefficient of static friction, and bulk and true densities) of the white and blue form of dragonhead seeds were not significantly different. Both forms of dragonhead showed similar levels of protein (average of 21%), whereas the blue form of dragonhead had a lower fat content (average of 23.1%) and higher mucilage content (13.35%) in comparison to the blue form of seed (24.6 and 9.95%, respectively). Antioxidant capacity of dragonhead seeds was comparable for both forms and averaged about 40%, which corresponded to EC50 values of 0.12 and 0.13 mgml-1 for the white and blue forms, respectively. The grinding material showed similar particle size distribution of ground material for both forms of dragonhead seeds. The lowest values of specific grinding energy were obtained for the white form of dragonhead seeds, those for the blue form were significantly higher. Grinding of dragonhead seeds using a screen 2.0 mm mesh size caused screen hole clogging. This problem did not occur when dragonhead seeds were mixed with wheat grain.

Dziki, D.; Mi?, A.; G?adyszewska, B.; Laskowski, J.; Kwiatkowski, S.; Gawlik-Dziki, U.

2013-12-01

273

Eastern Frequency Response Study  

SciTech Connect

This study was specifically designed to investigate the frequency response of the Eastern Interconnection that results from large loss-of-generation events of the type targeted by the North American Electric Reliability Corp. Standard BAL-003 Frequency Response and Frequency Bias Setting (NERC 2012a), under possible future system conditions with high levels of wind generation.

Miller, N.W.; Shao, M.; Pajic, S.; D'Aquila, R.

2013-05-01

274

Influence of fruit ripeness at the time of seed extraction on pepper ( Capsicum annuum) seed germination  

Microsoft Academic Search

The influence of fruit ripeness (half ripe, fully ripe, overripe) at the time of seed extraction on seed germination behaviour, at 25 °C and 13 °C, was studied in two Spanish pepper cultivars for canning. Seeds from half ripe fruits had a poorer behaviour than those taken from fully ripe fruits, especially at 13 °C. Room ripening and overripening of

Jose Cavero; Ramiro Gil Ortega; Carlos Zaragoza

1995-01-01

275

Susan's Lemon Poppy Seed Cake 2 oz. Black poppy seeds (4 tbs.)*  

E-print Network

Susan's Lemon Poppy Seed Cake 2 oz. Black poppy seeds (4 tbs.)* 4 oz. Self-raising flour (just and poppy seeds. Bake in a greased loaf tin for about 30 min. Ten minutes before the cake is due to come out

Lamond, Angus I.

276

Seed size and provenance mediate the joint effects of disturbance and seed predation on community  

E-print Network

or experimentally disturbed subplots in and out of larger rodent exclusion plots at ten grassland sites acrossSeed size and provenance mediate the joint effects of disturbance and seed predation on community interactions such as post-dispersal seed predation and disturbance, which dictate what species actually

277

FACTORS LIMITING CAPSULE SET, SEED SET AND REPRODUCTIVE SUCCESS IN EUCALYPTUS GLOBULUS SEED ORCHARDS  

Microsoft Academic Search

Low capsule set is a major factor limiting seed production in Eucalyptus globulus seed orchards. Trials were conducted in E. globulus seed orchards in Tasmania to identify the timing of capsule development and abortion, as well as the effect of pollination type, female tree, site, fertilisation, flower physical attributes, flower density, irrigation and weather events on capsule set and overall

S. Suitor; B. M. Potts; P. H. Brown; A. J. Gracie; P. L. Gore

2007-01-01

278

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

279

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

280

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

281

Two-phase seed dispersal: linking the effects of frugivorous birds and seed-caching rodents.  

PubMed

Frugivorous birds disperse the seeds of many fruit-bearing plants, but the fate of seeds after defecation or regurgitation is often unknown. Some rodents gather and scatter hoard seeds, and some of these may be overlooked, germinate, and establish plants. We show that these two disparate modes of seed dispersal are linked in some plants. Rodents removed large (>25 mg) seeds from simulated bird feces (pseudofeces) at rates of 8-50%/day and scatter hoarded them in soil. Ants (Formica sibylla) also harvested some seeds and carried them to their nests. Rodents carried seeds 2.5+/-3.2 m to cache sites (maximum 12 m) and buried seeds at 8+/-7 mm depth. Enclosure studies suggest that yellow pine chipmunks (Tamias amoenus) and deer mice (Peromyscus maniculatus) made the caches. In spring, some seeds germinated from rodent caches and established seedlings, but no seedlings established directly from pseudofeces. This form of two-phase seed dispersal is important because each phase offers different benefits to plants. Frugivory by birds permits relatively long-range dispersal and potential colonization of new sites, whereas rodent caching moves seeds from exposed, low-quality sites (bird feces on the ground surface) to a soil environment that may help maintain seed viability and promote successful seedling establishment. PMID:15959820

Vander Wall, Stephen B; Kuhn, Kellie M; Gworek, Jennifer R

2005-09-01

282

A seed predator drives the evolution of a seed dispersal mutualism  

Microsoft Academic Search

Although antagonists are hypothesized to impede the evolution of mutualisms, they may simultaneously exert selection favouring the evolution of alternative mutualistic interactions. We found that increases in limber pine (Pinus flexilis) seed defences arising from selection exerted by a pre-dispersal seed predator (red squirrel Tamiasciurus hudsonicus) reduced the efficacy of limber pine's primary seed disperser (Clark's nutcracker Nucifraga columbiana) while

Adam M. Siepielski; Craig W. Benkman

2008-01-01

283

Seeding date influence on camelina seed yield, yield components, and oil content in Chile  

Microsoft Academic Search

Camelina (Camelina sativa L.) was introduced for the first time in Chile in 2008 as a potential feedstock for biodiesel and also as high omega-3-containing seed oil for the salmon feed industry. The objective of this study was to determine the optimum seeding date to maximize camelina seed yield in South Central Chile. The experiment was conducted under dryland conditions

Marisol Berti; Rosemarie Wilckens; Susana Fischer; Alejandro Solis; Burton Johnson

2011-01-01

284

Bulk YBCO seeded with 45°-45° bridge-seeds of different lengths  

NASA Astrophysics Data System (ADS)

Single grain, (RE)BCO (rare earth-barium-copper oxide) bulk superconductors in large or complicated geometries are required for a variety of potential applications, such as in motors and generators and magnetic shielding devices. As a result, top, multi-seeded, melt growth has been investigated over the past 15 years in an attempt to enlarge the size of (RE)BCO single grains specifically for such applications. Of these multi-seeding techniques, so-called bridge-seeding provides the best alignment of two seeds in a single grain growth process. Here we report, for the first time, the successful growth of YBCO (yttrium-barium-copper oxide) using a special, 45°-45°, arrangement of bridge-seeds. The superconducting properties, including trapped field, of the multi-seeded YBCO grains have been measured for different bridge lengths of the 45°-45° bridge-seeds. The boundaries at the impinging growth front and the growth features of the top, multi-seeded surface and cross-section of the multi-seeded, samples have been analysed using optical microscopy. The results suggest that an impurity-free boundary between the two seeds of each leg of the bridge-seed can form when 45°-45° bridge-seeds are used to enlarge the size of YBCO grains.

Shi, Y.-H.; Durrell, J. H.; Dennis, A. R.; Cardwell, D. A.

2013-01-01

285

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

286

The relationship between seed rain and the soil seed bank in a temperate rainforest stand near Auckland, New Zealand  

Microsoft Academic Search

Composition of the germinable seed rain and the soil seed bank is documented for five sites in temperate rainforest near Auckland, New Zealand, in an effort to understand the dynamics of the soil seed bank. The seed rain added a mean of 202 ± 93 germinable seeds per 0.1 m over 15 months to the forest floor in 1988 and

G. Sem; N. J. Enright

1996-01-01

287

Male genotype influences seed set and seed size in controlled crosses of American chestnut (Castanea dentata [Marsh] Borhk)  

E-print Network

The fruit of a chestnut tree, a chestnut, is composed of a maternally derived pellicle enclosing a seed trees are resulting in the creation of seed orchards that will produce American chestnut hybrid seed for outplanting (Burnham et al. 1986). Chestnut seed orchards must efficiently produce high-quality seed to meet

288

Effects of Gut Passage, Feces, and Seed Handling on Latency and Rate of Germination in Seeds Consumed by  

E-print Network

of primary seed dispersal by animals is the quality of seed dispersal (Schupp: Plant Ecol 107/108 [1993] 15 of seeds dispersed and the quality of dispersal provided each seed'' (Schupp, 1993). Here, we focus on the latter. Although the quantity com- ponent of seed dispersal effectiveness (sensu Schupp, 1993) refers

Fedigan, Linda M.

289

Sterols in pumpkin seed oil  

Microsoft Academic Search

and summary  The sterol fraction of unsaponifiable matter obtained from a Yugoslav pumpkin seed ripening was investigated by gas liquid\\u000a chromatography on a glass capillary column. It contained at least 14 different sterols ten of which were identified primarily\\u000a by combined gas chromatography-mass spectrometry as cholesterol, brassicasterol, campesterol, stigmasterol, 24-methylcholest-7-en-3?-ol,\\u000a ?7,22,25-stimastatrien-3?-ol, ?-spinasterol, ?7,25-stigmastadien-3?-ol, ?7,25-stigmastenol, and ?7-avenasterol. It was shown that the

M. Basti?; Lj. Basti?; J. A. Jovanovi?; G. Spiteller

1977-01-01

290

The seeded growth of graphene  

NASA Astrophysics Data System (ADS)

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

2014-07-01

291

Frequency Bin Entangled Photons  

E-print Network

A monochromatic laser pumping a parametric down conversion crystal generates frequency entangled photon pairs. We study this experimentally by addressing such frequency entangled photons at telecommunication wavelengths (around 1550 nm) with fiber optics components such as electro-optic phase modulators and narrow band frequency filters. The theory underlying our approach is developed by introducing the notion of frequency bin entanglement. Our results show that the phase modulators address coherently up to eleven frequency bins, leading to an interference pattern which can violate a Bell inequality adapted to our setup by more than five standard deviations.

L. Olislager; J. Cussey; A. T. Nguyen; Ph. Emplit; S. Massar; J. -M. Merolla; K. Phan Huy

2009-10-07

292

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. PMID:17298989

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

2007-01-01

293

Management and Conservation Article Agricultural Seed Biomass for Migrating  

E-print Network

Management and Conservation Article Agricultural Seed Biomass for Migrating and Wintering Waterfowl frequently acquire high-energy agricultural seeds in harvested and unharvested croplands during migration wetlands for migrating and wintering waterfowl because seed resources are low in harvested agricultural

Gray, Matthew

294

29 CFR 780.113 - Seeds, spawn, etc.  

...2014-07-01 2014-07-01 false Seeds, spawn, etc. 780.113 ...Horticultural Commodities § 780.113 Seeds, spawn, etc. Seeds and seedlings of agricultural and...Thus, since mushrooms and beans are considered...

2014-07-01

295

High-frequency transformation of Arabidopsis thaliana by Agrobacterium tumefaciens  

Microsoft Academic Search

Incorporation of 5 mg\\/L silver thiosulphate into media for seed germination and callus induction, as used in the transformation\\u000a protocol originally described by Valvekens et al. (1988), was found to increase the frequency of regeneration of transformants\\u000a ofArabidopsis thaliana ecotypes C24 and Landsbergerecta by at least 10- to 100-fold. Other factors, such as density of the bacterial inoculation culture, density

Michael C. Clarke; Wenbin Wei; Keith Lindsey

1992-01-01

296

Recovery and Germination of Grass Seeds Ingested by Cattle  

Microsoft Academic Search

Seeds of bluebunch wheatgrass (Psuedoroegneria spicata (Pursh) A. Love) and Sandberg bluegrass (Poa secunda Presl.) were fed to Holstein heifers in different amounts to investigate the effects of seed feeding level and seed size on the recovery and germinability of passed seed. Animals were fed 60,000, 30,000,15,000, and 7,500 seeds of each species. Passed seeds were recovered from dungcollected daily

Ferhat Gokbulak

2006-01-01

297

Spatial and temporal variation of seed predation and removal of sympatric large-seeded species in relation to innate seed traits in a subtropical forest, Southwest China  

Microsoft Academic Search

Based on the complex seed packaging strategies involving morphology, nutrition quality and secondary chemistry, spatial and temporal variation of seed predation and removal by granivorous rodents was examined among six sympatric large-seeded tree species with different seed traits: Lithocarpus harlandii, Quercus variabilis, Q. serrata, Cyclobalanopsis glauca and Castanopsis fargesii (Fagaceae); Camellia oleifera (Theaceae) across different stands and seasons in a

Zhishu Xiao; Yushan Wang; Marvin Harris; Zhibin Zhang

2006-01-01

298

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

Microsoft Academic Search

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

Xiaojun Du; Qinfeng Guo; Xianming Gao; Keping Ma

2007-01-01

299

Genetics of seed storage proteins in the love tree Cercis siliquastrum L. (Fabaceae).  

PubMed

The patterns of C. siliquastrum seed storage proteins ("cercins") are described using SDS-polyacrylamide gel electrophoresis. The polypeptides detected had very different molecular weights (ranging from 168 to 34 KDa) which, together with their high homogeneity, produced a very good resolution of bands. These proteins could be ascribed to five different loci. The analysis of seed sets of individual trees indicated that the love tree is almost completely autogamous with less than 5% of outcrosses. Although this mode of reproduction seems to produce a decrease in heterozygote frequency among the seeds of the population analysed, the levels of variability detected were very high for an autogamous plant: all of the loci were polymorphic, with a mean heterozygosity of 0.327 and a polymorphic index of 0.412. Protein segregation revealed a strong genetic linkage between three cercin loci (a, c and d) while the other two are independent. PMID:24178101

González, C; Henriques-Gil, N

1994-12-01

300

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

301

Lesquerella seed pretreatment to improve germination  

Microsoft Academic Search

Lesquerella fendleri is a potential oilseed crop. Seed dormancy, including light requirement, is common in many small-seeded species native to arid and semiarid environments, and may be a major contributor to stand establishment difficulties in Lesquerella. Gibberellic acid (GA3) and potassium nitrate (KNO3) in solutions of water have been shown to be effective moistening agents for improving germination and reducing

Naveen Puppala; James L Fowler

2003-01-01

302

Volatile components in okra seed coat  

Microsoft Academic Search

The volatile compounds in the coat of okra seeds can be released by simple rubbing of the seeds. They were isolated by hexane extraction and steam distillation to give the essential oil (EO) and by head space (HS) condensation. 72 compounds were identified in the study (40 esters and 24 sesquiterpenes and derivatives).The most abundant compound was 2-methylbutyl 2-methylbutanoate which

Marius Camciuc; Jean Marie Bessière; Gérard Vilarem; Antoine Gaset

1998-01-01

303

Organic acids as seed germination inhibitors  

Microsoft Academic Search

Phytotoxicity of aromatic and aliphatic acids was tested by a wheat seed bioassay. Wheat seed germination was found to be influenced by the number of hydroxy and methoxy groups, the molecular position of single and double hydroxy groups, the length of the aliphatic chain, as well as by the pKa of the acid solutions. Orto and meta coumaric, ferulic and

A. Saviozzi; R. Riffaldi

1994-01-01

304

Seed Dispersal Velocity in Four Dwarfmistletoes  

Microsoft Academic Search

By means of a high-speed photographic technique, the initial velocities of seeds were studied as they were expelled from the fruits of four Colorado dwarfmistletoes: Arceuthobium douglasii, A. campylopodum f. cyanocarpum, A. vaginatum f. cryptopodum, and A. americanum. Velocities of the seeds of the latter two species averaged 2600 centimeters per second and were significantly greater than those of the

T. E. Hinds; F. G. Hawksworth

1965-01-01

305

Comparative seed morphology of Mexican Nymphaea species  

Microsoft Academic Search

Seed morphology was studied in 10 species belonging to three subgenera of Nymphaea occurring in Mexico: subgenus Brachyceras (N. ampla, N. elegans, N. gracilis, N. pulchella); subgenus Hydrocallis (N. amazonum, N. conardii, N. jamesoniana, N. novogranatensis); and subgenus Nymphaea (N. mexicana, N. odorata). Phenetic relationships of Mexican species of Nymphaea were studied by cluster analysis (UPGMA). Among subgenera, the seeds

Jaime Bonilla-Barbosa; Alejandro Novelo; Yolanda Hornelas Orozco; Judith Márquez-Guzmán

2000-01-01

306

Determinants of seed production in Geranium maculatum  

Microsoft Academic Search

We experimentally examined factors limiting seed production in two populations of the perennial woodland herb Geranium maculatum in central Illinois, USA. To test the pollinator-limitation hypothesis, we compared the seed production of plants whose flowers were supplementarily pollinated with outcross pollen to that of control plants receiving natural pollination only. To test if fruit production by early flowers suppresses fruit

Jon Ågren; Mary F. Willson

1992-01-01

307

Sucrose metabolism in lima bean seeds  

Microsoft Academic Search

Developing and germinating lima bean (Phaseolus lunatus var Cangreen) seeds were used for testing the sucrose synthase pathway, to examine the competition for uridine diphosphate (UDP) and pyrophosphate (PPi), and to identify adaptive and maintenance-type enzymes in glycolysis and gluconeogenesis. In developing seeds, sucrose breakdown was dominated by the sucrose synthase pathway; but in the seedling embryos, both the sucrose

Dianpeng Xu; S.-J. S. Sung; S. Shijean; C. C. Black

1989-01-01

308

Statistical Evaluation of Cloud Seeding Operations  

Microsoft Academic Search

Modern commercial cloud seeding dates from the discovery in 1946 that silver iodide crystals are good nuclei for the formation of precipitation from cold clouds. Whether silver iodide seeding does actually increase the precipitation over what would occur naturally has been a controversial question.In 1953 Congress established the Advisory Committee on Weather Control, one of its responsibilities being to determine

K. A. Brownlee

1960-01-01

309

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. PMID:22566677

Ruxton, Graeme D.; Schaefer, H. Martin

2012-01-01

310

Sparse representation for weed seeds classification  

Microsoft Academic Search

In agricultural industry, there is a longing for highly efficient and reliable seeds classification methods. Fast implementation of the existing methods is of great economical importance. Almost all categories of weed seeds have different size, shape and texture, and even the same species are quantitatively diverse in feature. Therefore, feature extraction is a tough, time consuming and labor-intensive task. In

Ming Zhang; Cheng Cai; Junping Zhu

2010-01-01

311

Genetic basis of seed setting in alfalfa  

Microsoft Academic Search

The genetic basis of seed setting was evaluated in seven clones of alfalfa selected under predominantly self-pollinating conditions. They were hand crossed in all possible combinations. Their compatibility was studied by the percentage of flowers forming pods and number of seeds per pod during crossing. The variances for GCA, SCA and reciprocal effects were significant for percentage of pod set

S. M. Singh

1978-01-01

312

Physicochemical changes of oat seeds during germination  

Microsoft Academic Search

The physicochemical properties of native and germinated oat seeds cultivated in China and their correlations were investigated. The growth curve during germination of oat seeds was described. The malt yield was 84% at the end of malting. The losses by removing of shoots and rootlets were the major cause of the total dry matter losses in the last 24h of

Binqiang Tian; Bijun Xie; John Shi; Jia Wu; Yan Cai; Tuoming Xu; Sophia Xue; Qianchun Deng

2010-01-01

313

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

314

Alterations in seed development gene expression affect size and oil content of Arabidopsis seeds.  

PubMed

Seed endosperm development in Arabidopsis (Arabidopsis thaliana) is under control of the polycomb group complex, which includes Fertilization Independent Endosperm (FIE). The polycomb group complex regulates downstream factors, e.g. Pheres1 (PHE1), by genomic imprinting. In heterozygous fie mutants, an endosperm develops in ovules carrying a maternal fie allele without fertilization, finally leading to abortion. Another endosperm development pathway depends on MINISEED3 (a WRKY10 transcription factor) and HAIKU2 (a leucine-rich repeat kinase). While the role of seed development genes in the embryo and endosperm establishment has been studied in detail, their impact on metabolism and oil accumulation remained unclear. Analysis of oil, protein, and sucrose accumulation in mutants and overexpression plants of the four seed development genes revealed that (1) seeds carrying a maternal fie allele accumulate low oil with an altered composition of triacylglycerol molecular species; (2) homozygous mutant seeds of phe1, mini3, and iku2, which are smaller, accumulate less oil and slightly less protein, and starch, which accumulates early during seed development, remains elevated in mutant seeds; (3) embryo-specific overexpression of FIE, PHE1, and MINI3 has no influence on seed size and weight, nor on oil, protein, or sucrose content; and (4) overexpression of IKU2 results in seeds with increased size and weight, and oil content of overexpressed IKU2 seeds is increased by 35%. Thus, IKU2 overexpression represents a novel strategy for the genetic manipulation of the oil content in seeds. PMID:24014578

Fatihi, Abdelhak; Zbierzak, Anna Maria; Dörmann, Peter

2013-10-01

315

Seed Production Characteristics of Some Introduced Warm-Season Grasses.  

E-print Network

seed costs. This Inay result from poor seed yields, low quality, tlilliculty ol harvest or other seeti protluction prob- len~r. Among the grasses which have shown some tlegrcc of atlaptation but which are limited by seed ~~.otluction or poor seed... seed costs. This Inay result from poor seed yields, low quality, tlilliculty ol harvest or other seeti protluction prob- len~r. Among the grasses which have shown some tlegrcc of atlaptation but which are limited by seed ~~.otluction or poor seed...

Holt, Ethan C.

1965-01-01

316

Alfalfa Seed Decontamination in Salmonella Outbreak  

PubMed Central

Based on in vitro data, the U.S. Food and Drug Administration recommends chemical disinfection of raw sprout seeds to reduce enteric pathogens contaminating the seed coats. However, little is known about the effectiveness of decontamination at preventing human disease. In 1999, an outbreak of Salmonella enterica serotype Mbandaka occurred in Oregon, Washington, Idaho, and California. Based on epidemiologic and pulsed-field gel electrophoresis evidence from 87 confirmed cases, the outbreak was linked to contaminated alfalfa seeds grown in California’s Imperial Valley. Trace-back and trace-forward investigations identified a single lot of seeds used by five sprout growers during the outbreak period. Cases of salmonellosis were linked with two sprout growers who had not employed chemical disinfection; no cases were linked to three sprout growers who used disinfection. This natural experiment provides empiric evidence that chemical disinfection can reduce the human risk for disease posed by contaminated seed sprouts. PMID:12702229

Gill, Christopher J.; Mohle-Boetani, Janet C.; Farrar, Jeff A.; Waller, Patti L.; Hahn, Christine G.; Cieslak, Paul R.

2003-01-01

317

Breaking of seed dormancy by catalase inhibition.  

PubMed Central

Germination of some dormant seeds is promoted by solutions of thiourea, sodium nitrite, and hydroxylamine salts. The promotions are accompanied by irreversible inhibition of catalase (EC 1.11.1.6) in extracts from the seeds. The seeds are also promoted in germination by catechol and pyrogallol solutions. These effects are recorded for lettuce (Lactuca sativa L. cv. Grand Rapids) and pigweed (Amaranthus albus L.) seeds. The results indicae that metabolically derived hydrogen peroxide, spared from decomposition by catalase inhibition, oxidizes reduced NADPH required as the oxidant in the pentose pathway of glucose use. The metabolic system for such use of H2O2 involves the enzymes, peroxidase (EC 1.11.1.7) and pyridine nucleotide quinone oxidoreductase (EC 1.6.99.2), which are present in the dormant seed prior to imbibition of water. PMID:235126

Hendricks, S B; Taylorson, R B

1975-01-01

318

Molecular regulation of seed and fruit set.  

PubMed

Seed and fruit set are established during and soon after fertilization and determine seed and fruit number, their final size and, hence, yield potential. These processes are highly sensitive to biotic and abiotic stresses, which often lead to seed and fruit abortion. Here, we review the regulation of assimilate partitioning, including the potential roles of recently identified sucrose efflux transporters in seed and fruit set and examine the similarities of sucrose import and hydrolysis for both pollen and ovary sinks, and similar causes of abortion. We also discuss the molecular origins of parthenocarpy and the central roles of auxins and gibberellins in fruit set. The recently completed strawberry (Fragaria vesca) and tomato (Solanum lycopersicum) genomes have added to the existing crop databases, and new models are starting to be used in fruit and seed set studies. PMID:22776090

Ruan, Yong-Ling; Patrick, John W; Bouzayen, Mondher; Osorio, Sonia; Fernie, Alisdair R

2012-11-01

319

Seed concentration control of metal nanowire diameter.  

PubMed

Gold/silver nanowires (NWs) of controlled diameters were synthesized from catalytic metal seed particles at the substrate/solution interface. Small seed nanoparticles of three different sizes: ~1 nm (11 gold atoms), ~1.4 nm (~55 gold atoms), and homemade nanoparticles of ~2 nm were used. By varying a single type of seed particle concentration in the growth solution, the NW diameters and morphology could be controlled, between bundles of ultrathin NWs of ~2-3 nm diameter to thicker isolated single NWs with a mean diameter of ~16 nm. In addition, the catalytic reduction rate leading to NW growth was found to be seed size dependent at small seed sizes (<2 nm). The two types of metallic NW films were tested for their performance as transparent electrodes after additional metal deposition for their stabilization and conductivity enhancement. The thin NW bundles exhibit superior transparent conductor properties. PMID:23030846

Azulai, Daniel; Cohen, Elad; Markovich, Gil

2012-11-14

320

Seed Maturation Regulators Are Related to the Control of Seed Dormancy in Wheat (Triticum aestivum L.).  

PubMed

In Arabidopsis, the regulation network of the seed maturation program controls the induction of seed dormancy. Wheat EST sequences showing homology with the master regulators of seed maturation, LEAFY COTYLEDON1 (LEC1), LEC2 and FUSCA3 (FUS3), were searched from databases and designated respectively as TaL1L (LEC1-LIKE), TaL2L (LEC2-LIKE), and TaFUS3. TaL1LA, TaL2LA and TaFUS3 mainly expressed in seeds or embryos, with the expression limited to the early stages of seed development. Results show that tissue-specific and developmental-stage-dependent expressions are similar to those of seed maturation regulators in Arabidopsis. In wheat cultivars, the expression level of TaL1LA is correlated significantly with the germination index (GI) of whole seeds at 40 days after pollination (DAP) (r?=?-0.83**). Expression levels of TaFUS3 and TaL2LA are significantly correlated respectively with GIs at 40 DAP and 50 DAP, except for dormant cultivars. No correlation was found between the expression level of TaVP1, orthologue of ABA INSENSITIVE3 (ABI3), and seed dormancy. DELAY OF GERMINATION1 (DOG1) was identified as a quantitative trait locus (QTL) for the regulation of seed dormancy in Arabidopsis. Its promoter has RY motif, which is a target sequence of LEC2. Significant correlation was found between the expression of TaDOG1 and seed dormancy except for dormant cultivars. These results indicate that TaL1LA, TaL2LA, and TaFUS3 are wheat orthologues of seed maturation regulators. The expressions of these genes affect the level of seed dormancy. Furthermore, the pathways, which involve seed maturation regulators and TaDOG1, are important for regulating seed dormancy in wheat. PMID:25211528

Rikiishi, Kazuhide; Maekawa, Masahiko

2014-01-01

321

Weed seeds on clothing: a global review.  

PubMed

Weeds are a major threat to biodiversity including in areas of high conservation value. Unfortunately, people may be unintentionally introducing and dispersing weed seeds on their clothing when they visit these areas. To inform the management of these areas, we conducted a systematic quantitative literature review to determine the diversity and characteristics of species with seeds that can attach and be dispersed from clothing. Across 21 studies identified from systematic literature searches on this topic, seeds from 449 species have been recorded on clothing, more than double the diversity found in a previous review. Nearly all of them, 391 species, are listed weeds in one or more countries, with 58 classified as internationally-recognised environmental weeds. When our database was compared with weed lists from different countries and continents we found that clothing can carry the seeds of important regional weeds. A total of 287 of the species are listed as aliens in one or more countries in Europe, 156 are invasive species/noxious weeds in North America, 211 are naturalized alien plants in Australia, 97 are alien species in India, 33 are invasive species in China and 5 are declared weeds/invaders in South Africa. Seeds on the clothing of hikers can be carried to an average distance of 13 km, and where people travel in cars, trains, planes and boats, the seeds on their clothing can be carried much further. Factors that affect this type of seed dispersal include the type of clothing, the type of material the clothing is made from, the number and location of the seeds on plants, and seed traits such as adhesive and attachment structures. With increasing use of protected areas by tourists, including in remote regions, popular protected areas may be at great risk of biological invasions by weeds with seeds carried on clothing. PMID:24956465

Ansong, Michael; Pickering, Catherine

2014-11-01

322

Frequency invariant interferometry  

NASA Astrophysics Data System (ADS)

This paper discusses frequency-independent phase comparison interferometry as a method of direction finding. Theoretical relationships are derived that show the electrical phase between two elements of an array can remain approximately constant over frequency. The theory is developed for log-periodic dipole arrays. Design and fabrication of a two-element interferometer using log-periodic antennas are discussed. Experimental results are presented which show that this array remains frequency independent over a three-octave bandwidth.

Musselman, Randall L.; Norgard, John D.

1992-05-01

323

Nonlinear Frequency Compression  

PubMed Central

Frequency lowering technologies offer an alternative amplification solution for severe to profound high frequency hearing losses. While frequency lowering technologies may improve audibility of high frequency sounds, the very nature of this processing can affect the perceived sound quality. This article reports the results from two studies that investigated the impact of a nonlinear frequency compression (NFC) algorithm on perceived sound quality. In the first study, the cutoff frequency and compression ratio parameters of the NFC algorithm were varied, and their effect on the speech quality was measured subjectively with 12 normal hearing adults, 12 normal hearing children, 13 hearing impaired adults, and 9 hearing impaired children. In the second study, 12 normal hearing and 8 hearing impaired adult listeners rated the quality of speech in quiet, speech in noise, and music after processing with a different set of NFC parameters. Results showed that the cutoff frequency parameter had more impact on sound quality ratings than the compression ratio, and that the hearing impaired adults were more tolerant to increased frequency compression than normal hearing adults. No statistically significant differences were found in the sound quality ratings of speech-in-noise and music stimuli processed through various NFC settings by hearing impaired listeners. These findings suggest that there may be an acceptable range of NFC settings for hearing impaired individuals where sound quality is not adversely affected. These results may assist an Audiologist in clinical NFC hearing aid fittings for achieving a balance between high frequency audibility and sound quality. PMID:23539261

Scollie, Susan; Glista, Danielle; Seelisch, Andreas

2013-01-01

324

Frequencies of solar oscillations  

NASA Technical Reports Server (NTRS)

Solar oscillations have been observed at three different spatial scales at Big Bear Solar Observatory during 1986-1987 and, using three data sets, a new and more accurate table of solar oscillation frequencies has been compiled. The oscillations, which are presented as functions of radial order n and spherical harmonic degree l, are averages over azimuthal order and therefore approximate the normal mode frequencies of a nonrotating, spherically symmetric sun, near solar minimum. The table contains frequencies for most of the solar p and f modes with l between 0 and 1860, n between 0 and 26, and oscillation mode frequencies between 1.0 and 5.3.

Libbrecht, K. G.; Woodard, M. F.; Kaufman, J. M.

1990-01-01

325

Responses of seed germination, seedling growth, and seed yield traits to seed pretreatment in maize (Zea mays L.).  

PubMed

A series of seed priming experiments were conducted to test the effects of different pretreatment methods to seed germination, seedling growth, and seed yield traits in maize (Zea mays L.). Results indicated that the seeds primed by gibberellins (GA), NaCl, and polyethylene glycol (PEG) reagents showed a higher imbibitions rate compared to those primed with water. The final germination percentage and germination rate varied with different reagents significantly (P < 0.05). The recommended prime reagents were GA at 10?mg/L, NaCl at 50?mM, and PEG at 15% on account of germination experiment. 15% PEG priming reagent increased shoot and root biomass of maize seedling. The shoot biomass of seedlings after presoaking the seeds with NaCl reagent was significantly higher than the seedlings without priming treatment. No significant differences of plant height, leaf number, and hundred-grain weight were observed between control group and priming treatments. Presoaking with water, NaCl (50?mM), or PEG (15%) significantly increased the hundred-grain weight of maize. Therefore, seed pretreatment is proved to be an effective technique to improve the germination performance, seedling growth, and seed yield of maize. However, when compared with the two methods, if immediate sowing is possible, presoaking is recommended to harvest better benefits compared to priming method. PMID:25093210

Tian, Yu; Guan, Bo; Zhou, Daowei; Yu, Junbao; Li, Guangdi; Lou, Yujie

2014-01-01

326

Electrophysiological Low-Frequency Coherence and Cross-Frequency Coupling  

E-print Network

to interareal BOLD correlations. The low-frequency oscillations also influenced local pro- cessing by modulatingNeuron Article Electrophysiological Low-Frequency Coherence and Cross-Frequency Coupling Contribute in the task-free state. Low-frequency oscillations (

Kastner, Sabine

327

The functional evaluation of waste yuzu (Citrus junos) seeds.  

PubMed

We have succeeded in extracting a large amount of expensive limonoids and the high total antioxidant capability yuzu seed oil from waste yuzu seed by simple methods. Yuzu seeds contain higher amounts of fat-soluble limonoid aglycone (330.6 mg g(-1) of dry seed), water-soluble limonoid glycoside (452.0 mg g(-1) of dry seed), and oil (40 mg g(-1) of green seed) than other citrus fruits. The antioxidant activities of yuzu seed aglycone, glycoside, and seed oil were evaluated in vitro. The potential antioxidant activity in oil solution, diphenylpicrylhydrazyl radical-scavenging activity, and hydrogen peroxide-scavenging activity effects of the seed extracts were also investigated. The antioxidant activity of yuzu seed oil was two times that of grapefruit seed oil, which has high activity. Yuzu glycoside produced the same high antioxidant activity as Luo Han Guo glycoside. PMID:24336775

Minamisawa, Mayumi; Yoshida, Shoichiro; Uzawa, Atsushi

2014-02-01

328

Dielectric and conductivity studies of the hydration mechanisms in plant seeds.  

PubMed Central

The hydration mechanism of various plant seeds has been investigated by a) sorption-desorption isotherms, b) ac-dielectric spectroscopy in the 10 Hz to 1 GHz frequency range and the -80 to + 40 degrees C temperature range, and c) thermally stimulated depolarization current techniques in the -170 to + 23 degrees C temperature range. Seeds of different chemical composition were studied at water contents varying between 0 and 40% w/w (dry weight basis). Our experimental results permitted us to determine i) the diffusion constant of water in the samples, found to be between 1.4 x 10(-11) and 3.7 x 10(-11) m2/s; ii) a critical water content corresponding to the completion of the primary hydration layer, which is in the range 0.11-0.17 w/w, depending on the seed nature; and iii) the activation energy of the main relaxation mechanism, found to be equal to 0.54 +/- 0.05 eV. Moreover, they make it possible to investigate the dependence of various parameters (conductivity, molecular mobility, plasticizing effect of water) on the water content of the sample, to follow the crystallization of water in the seeds as a function of temperature and confirm that it is not a reversible process, to study the dehydration process as a function of temperature and time, and to propose an alternative technique for the determination of the moisture content in seeds. PMID:8785305

Konsta, A A; Pissis, P; Kanapitsas, A; Ratkovic, S

1996-01-01

329

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

330

Physical dormancy in seeds: a game of hide and seek?  

PubMed

Historically, 'physical dormancy', or 'hard seededness', where seeds are prevented from germinating by a water-impermeable seed coat, is viewed as a dormancy mechanism. However, upon water uptake, resumption of metabolism leads to the unavoidable release of volatile by-products, olfactory cues that are perceived by seed predators. Here, we examine the hypothesis that hard seeds are an anti-predator trait that evolved in response to powerful selection by small mammal seed predators. Seeds of two legume species with dimorphic seeds ('hard' and 'soft'), Robinia pseudoacacia and Vicia sativa, were offered to desert hamsters (Phodopus roborovskii) in a series of seed removal studies examining the differences in seed harvest between hard and soft seeds. Volatile compounds emitted by dry and imbibed soft seeds were identified by headspace gas chromatography-mass spectrometry (GC-MS). Fourteen main volatile compounds were identified, and hamsters readily detected both buried imbibed seeds and an artificial 'volatile cocktail' that mimicked the scent of imbibed seeds, but could not detect buried hard or dry soft seeds. We argue that physical dormancy has evolved to hide seeds from mammalian predators. This hypothesis also helps to explain some otherwise puzzling features of hard seeds and has implications for seed dispersal. PMID:23421728

Paulsen, Torbjørn Rage; Colville, Louise; Kranner, Ilse; Daws, Matthew I; Högstedt, Göran; Vandvik, Vigdis; Thompson, Ken

2013-04-01

331

A low jitter single frequency Q-switched laser from solid state to optical fiber configuration  

NASA Astrophysics Data System (ADS)

This paper will get to the bottom of the mechanism of a superior inject seeding technology, and take it even further, from the solid state laser into the fiber laser configuration. This low jitter, single frequency Q-switched solid state laser with precisely controllable firing time was realized, developed and reported previously, in which the oscillator can output energy of near 100 mJ and the master oscillator power amplifier (MOPA) reaches the output energy of 300 mJ, operating at a wavelength of 1064 nm, with a pulse width of 10 ns and in near single transversal mode. Comparing two existing commercial techniques, ramp-and-fire and pulse-to-pulse buildup time reduction, this report presents a full understanding of using a CW transformed injection seeding method in which this technique is immune to mechanical vibration or thermal expansion, and it is able to precisely control the high peak energy launching time within a nanosecond jitter and achieve single frequency operation at the same time. It is carefully observed that the CW seeding mechanism is similar but not equivalent to a pulsed seeding with pulse width shorter or equal to the ring cavity length. The advantage of the realized regime is that in stable laser operation there is no need to adjust the slave cavity length to match the seeded light longitudinal mode. Therefore, the extremely strict mechanical requirement can be relaxed. It is found that the slave laser frequency follows exactly to the injected seeded laser's frequency which can also provide frequency tuning, control and locking.

Wu, Frank F.

2013-03-01

332

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

333

A seed predator drives the evolution of a seed dispersal mutualism  

PubMed Central

Although antagonists are hypothesized to impede the evolution of mutualisms, they may simultaneously exert selection favouring the evolution of alternative mutualistic interactions. We found that increases in limber pine (Pinus flexilis) seed defences arising from selection exerted by a pre-dispersal seed predator (red squirrel Tamiasciurus hudsonicus) reduced the efficacy of limber pine's primary seed disperser (Clark's nutcracker Nucifraga columbiana) while enhancing seed dispersal by ground-foraging scatter-hoarding rodents (Peromyscus). Thus, there is a shift from relying on primary seed dispersal by birds in areas without red squirrels, to an increasing reliance on secondary seed dispersal by scatter-hoarding rodents in areas with red squirrels. Seed predators can therefore drive the evolution of seed defences, which in turn favour alternative seed dispersal mutualisms that lead to major changes in the mode of seed dispersal. Given that adaptive evolution in response to antagonists frequently impedes one kind of mutualistic interaction, the evolution of alternative mutualistic interactions may be a common by-product. PMID:18460433

Siepielski, Adam M; Benkman, Craig W

2008-01-01

334

A seed predator drives the evolution of a seed dispersal mutualism.  

PubMed

Although antagonists are hypothesized to impede the evolution of mutualisms, they may simultaneously exert selection favouring the evolution of alternative mutualistic interactions. We found that increases in limber pine (Pinus flexilis) seed defences arising from selection exerted by a pre-dispersal seed predator (red squirrel Tamiasciurus hudsonicus) reduced the efficacy of limber pine's primary seed disperser (Clark's nutcracker Nucifraga columbiana) while enhancing seed dispersal by ground-foraging scatter-hoarding rodents (Peromyscus). Thus, there is a shift from relying on primary seed dispersal by birds in areas without red squirrels, to an increasing reliance on secondary seed dispersal by scatter-hoarding rodents in areas with red squirrels. Seed predators can therefore drive the evolution of seed defences, which in turn favour alternative seed dispersal mutualisms that lead to major changes in the mode of seed dispersal. Given that adaptive evolution in response to antagonists frequently impedes one kind of mutualistic interaction, the evolution of alternative mutualistic interactions may be a common by-product. PMID:18460433

Siepielski, Adam M; Benkman, Craig W

2008-08-22

335

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

336

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. PMID:16665932

Ensminger, Peter A.; Ikuma, Hiroshi

1988-01-01

337

Photoinduced Seed Germination of Oenothera biennis L  

PubMed Central

General characteristics of light-induced germination of Oenothera biennis L. seeds were investigated at 24°C. During dark imbibition, seeds reached maximal respiration in 7 hours and maximal water content and photosensitivity in 24 hours. After dark imbibition of 24 hours, seeds required a long exposure (>36 hours) to red or white light for maximal germination. Two photoperiods (12 and 2 hours) separated by a period of darkness of 10 to 16 hours gave near maximal germination. For the two photoperiod regime, the first light potentiates a reversible phytochrome response by the second light. A 35°C treatment for 2 to 3 hours in the dark immediately prior or subsequent to 8 hours of light caused a higher percentage of germination. A 2 hour treatment at 35°C also potentiates a reversible phytochrome response. Halved seeds germinated at 100% in light or darkness indicating that the light requirement of the seeds is lost in the halving procedure. After-ripened seeds required less light and germinated more rapidly and at higher percentages than seeds tested shortly after maturation. PMID:16665824

Ensminger, Peter A.; Ikuma, Hiroshi

1987-01-01

338

Cell cycle control and seed development  

PubMed Central

Seed development is a complex process that requires coordinated integration of many genetic, metabolic, and physiological pathways and environmental cues. Different cell cycle types, such as asymmetric cell division, acytokinetic mitosis, mitotic cell division, and endoreduplication, frequently occur in sequential yet overlapping manner during the development of the embryo and the endosperm, seed structures that are both products of double fertilization. Asymmetric cell divisions in the embryo generate polarized daughter cells with different cell fates. While nuclear and cell division cycles play a key role in determining final seed cell numbers, endoreduplication is often associated with processes such as cell enlargement and accumulation of storage metabolites that underlie cell differentiation and growth of the different seed compartments. This review focuses on recent advances in our understanding of different cell cycle mechanisms operating during seed development and their impact on the growth, development, and function of seed tissues. Particularly, the roles of core cell cycle regulators, such as cyclin-dependent-kinases and their inhibitors, the Retinoblastoma-Related/E2F pathway and the proteasome-ubiquitin system, are discussed in the contexts of different cell cycle types that characterize seed development. The contributions of nuclear and cellular proliferative cycles and endoreduplication to cereal endosperm development are also discussed.

Dante, Ricardo A.; Larkins, Brian A.; Sabelli, Paolo A.

2014-01-01

339

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

340

Frequency modulated oscillator  

NASA Technical Reports Server (NTRS)

A frequency modulated push-pull oscillator in which the non-linear characteristic of varactors producing frequency modulation is compensated for by an opposite non-linear characteristic of a field effect transistor providing modulating bias to the varactors is described.

Honnell, M. A. (inventor)

1977-01-01

341

Stabilized radio frequency quadrupole  

DOEpatents

A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

Lancaster, Henry D. (Orinda, CA); Fugitt, Jock A. (Berkeley, CA); Howard, Donald R. (Danville, CA)

1984-01-01

342

Do surface plant and soil seed bank populations differ genetically? A multipopulation study of the desert mustard Lesquerella fendleri (Brassicaceae).  

PubMed

Seed banks are an important component of many plant populations, but few empirical studies have investigated the genetic relationship between soil seeds and surface plants. We compared the genetic structure of soil seeds and surface plants of the desert mustard Lesquerella fendleri within and among five ecologically diverse populations at the Sevilleta National Wildlife Refuge in Central New Mexico. At each site, 40 Lesquerella surface plants and 40 samples of soil seeds were mapped and genetically analyzed using starch gel electrophoresis. Overall allele frequencies of soil seeds and surface plants showed significant differences across the five populations and within three of the five individual populations. Surface plants had significantly greater amounts of single and multilocus heterozygosity, and mean surface plant heterozygosity was also greater at the total population level and in four of the five individual populations. Overall soil seed (bot not surface plant) homozygosity was significantly greater than predicted by Hardy-Weinberg expectations at the total and individual population levels. Although F-alpha estimates revealed similarly small but significant genetic divergence within each life-history stage, estimates of coancestry showed that fine-scale (0.5-2 m) genetic correlations among the surface plant genotypes were roughly twice those of soil seed genotypes. An unweighted pair group method with arithrnetic mean cluster analysis indicated that in the two geographically closest sites, the surface plants were slightly more genetically similar to each other than to their own respective seed banks. We also found weak and/or negative demographic associations between Lesquerella soil seed and surface plant densities within each of the five sites. We discuss the difficulties involved with sampling and genetically comparing these two life-history stages. PMID:21684995

Cabin, R; Mitchell, R; Marshall, D

1998-08-01

343

Bird attributes, plant characteristics, and seed dispersal of Pera glabrata (Schott, 1858), (Euphorbiaceae) in a disturbed cerrado area.  

PubMed

Several plant characteristics, such as fruit production, nutrient reward, secondary compounds, and fruit color display, affect fruit choice by birds. On the other hand, several bird attributes affect their efficiency as dispersers. Here we investigate the ornithochoric seed dispersal of Pera glabrata Schott (Euphorbiaceae) in a cerrado fragment in southeastern Brazil. A set of bird attributes, such as frequency of visits, number of diaspores eaten, time spent foraging, methods of taking and handling the diaspores and agonistic interactions were analyzed in order to infer about the potential of each species to act as a seed disperser. Birds were the unique seed dispersers of these oil-rich diaspores. We observed 414 bird visits during 60 hours of focal observations in five trees from December 1999 to January 2000. Twenty bird species from seven families ate the diaspores of P. glabrata, but only 14 species were considered potential seed dispersers because they swallowed the diaspores, increasing the probabilities for the seeds to be defecated and/or regurgitated away from the parent trees. The main potential seed dispersers were: Turdus leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) and Elaenia spp. (Tyrannidae). We did not find any significant seasonal change in the number of visits on the fruiting trees throughout the day. We also did not find any relation between the number of visits per tree and fruit production. The most effective seed dispersers of P. glabrata were generalist birds, which have a high visiting rate, high fruit consumption rate, and spend short periods on the plants. The large number of species recorded as potential seed dispersers of P. glabrata, being most of them very abundant even in Brazilian disturbed areas, may guarantee seed dispersal of this plant in small fragments and regenerating areas. PMID:18278313

Francisco, M R; Lunardi, V O; Galetti, M

2007-11-01

344

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.

345

SUPERMASSIVE SEEDS FOR SUPERMASSIVE BLACK HOLES  

SciTech Connect

Recent observations of quasars powered by supermassive black holes (SMBHs) out to z {approx}> 7 constrain both the initial seed masses and the growth of the most massive black holes (BHs) in the early universe. Here we elucidate the implications of the radiative feedback from early generations of stars and from BH accretion for popular models for the formation and growth of seed BHs. We show that by properly accounting for (1) the limited role of mergers in growing seed BHs as inferred from cosmological simulations of early star formation and radiative feedback, (2) the sub-Eddington accretion rates of BHs expected at the earliest times, and (3) the large radiative efficiencies {epsilon} of the most massive BHs inferred from observations of active galactic nuclei at high redshift ({epsilon} {approx}> 0.1), we are led to the conclusion that the initial BH seeds may have been as massive as {approx}> 10{sup 5} M{sub Sun }. This presents a strong challenge to the Population III seed model, which calls for seed masses of {approx}100 M{sub Sun} and, even with constant Eddington-limited accretion, requires {epsilon} {approx}< 0.09 to explain the highest-z SMBHs in today's standard {Lambda}CDM cosmological model. It is, however, consistent with the prediction of the direct collapse scenario of SMBH seed formation, in which a supermassive primordial star forms in a region of the universe with a high molecule-dissociating background radiation field, and collapses directly into a 10{sup 4}-10{sup 6} M{sub Sun} seed BH. These results corroborate recent cosmological simulations and observational campaigns which suggest that these massive BHs were the seeds of a large fraction of the SMBHs residing in the centers of galaxies today.

Johnson, Jarrett L.; Whalen, Daniel J.; Li Hui [Nuclear and Particle Physics, Astrophysics and Cosmology Group (T-2), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Holz, Daniel E., E-mail: jlj@lanl.gov [Enrico Fermi Institute, Department of Physics, and Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States)

2013-07-10

346

Nutritional evaluation of dried tomato seeds.  

PubMed

Two samples of tomato seeds, a by-product of the tomato canning industry were evaluated to determine proximate analysis, amino acid content, and digestibility, TMEn, and protein efficiency ratio. Tomato seeds were also used to replace corn and soybean meal (SBM) in a chick diet on an equal true amino acid digestibility and TMEn basis. Tomato seeds were found to contain 8.5% moisture, 25% CP, 20.0% fat, 3.1% ash, 35.1% total dietary fiber, 0.12% Ca, 0.58% P, and 3,204 kcal/kg of TMEn. The total amounts of methionine, cystine, and lysine in the tomato seeds were 0.39, 0.40, and 1.34%, respectively, and their true digestibility coefficients, determined in cecectomized roosters, were 75, 70, and 54%, respectively. The protein efficiency ratio (weight gain per unit of protein intake) value when fed to chicks at 9% CP was 2.5 compared to 3.6 for SBM (P < or = 0.05). When corn-SBM diets were formulated on an equal true amino acid digestibility and TMEn basis, up to 15% tomato seeds could replace corn and SBM without any adverse affects on chick weight gain, feed intake, or gain:feed ratio from 8 to 21 d posthatch. Tomato seeds at any level in the diet did not significantly affect skin pigmentation. Although the protein quality of tomato seeds may not be as high as SBM, tomato seeds do contain substantial amounts of digestible amino acids and TMEn. When formulating diets on a true digestible amino acid and TMEn basis, tomato seeds can be supplemented into chick rations at up to 15% without any adverse affects on growth performance. PMID:12580256

Persia, M E; Parsons, C M; Schang, M; Azcona, J

2003-01-01

347

Microfabricated ion frequency standard  

DOEpatents

A microfabricated ion frequency standard (i.e. an ion clock) is disclosed with a permanently-sealed vacuum package containing a source of ytterbium (Yb) ions and an octupole ion trap. The source of Yb ions is a micro-hotplate which generates Yb atoms which are then ionized by a ultraviolet light-emitting diode or a field-emission electron source. The octupole ion trap, which confines the Yb ions, is formed from suspended electrodes on a number of stacked-up substrates. A microwave source excites a ground-state transition frequency of the Yb ions, with a frequency-doubled vertical-external-cavity laser (VECSEL) then exciting the Yb ions up to an excited state to produce fluorescent light which is used to tune the microwave source to the ground-state transition frequency, with the microwave source providing a precise frequency output for the ion clock.

Schwindt, Peter (Albuquerque, NM); Biedermann, Grant (Albuquerque, NM); Blain, Matthew G. (Albuquerque, NM); Stick, Daniel L. (Albuquerque, NM); Serkland, Darwin K. (Albuquerque, NM); Olsson, III, Roy H. (Albuquerque, NM)

2010-12-28

348

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. PMID:23006315

2012-01-01

349

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

350

Some Physical Properties of Lentil Seeds  

Microsoft Academic Search

Several physical properties of lentil seed were evaluated as a function of moisture content. The average diameter, thickness, unit mass and volume of seed were 6·64 mm, 2·65 mm, 0·070 g and 49·08 mm3respectively at 6·5% m.c.d.b. Studies on rewetted seed showed that as moisture content increased from 6·5 to 32·6% d.b., bulk density decreased from 1190 to 935 kg\\/m3,

K. Çarman

1996-01-01

351

Seed Dispersal Velocity in Four Dwarfmistletoes.  

PubMed

By means of a high-speed photographic technique, the initial velocities of seeds were studied as they were expelled from the fruits of four Colorado dwarfmistletoes: Arceuthobium douglasii, A. campylopodum f. cyanocarpum, A. vaginatum f. cryptopodum, and A. americanum. Velocities of the seeds of the latter two species averaged 2600 centimeters per second and were significantly greater than those of the first two, which averaged 2200 centimeters per second. The initial velocity of 526 seeds of the four dwarfmistletoes averaged 2400 centimeters per second. PMID:17842843

Hinds, T E; Hawksworth, F G

1965-04-23

352

Germination Response of MR 219 Rice Variety to Different Exposure Times and Periods of 2450 MHz Microwave Frequency  

PubMed Central

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 GPa3 ranged from 93% to 98%, they failed to reduce the MGTa3. 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

Valdiani, Alireza; Maziah, Mahmood; Mohsenkhah, Mohammad

2013-01-01

353

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

354

Precision frequency synthesizing sources with excellent time/frequency performances  

NASA Technical Reports Server (NTRS)

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 excellent long term and short term frequency stability. Several precision frequency synthesizing sources developed by Beijing Institute of Radio Metrology and Measurement (BIRMM) which have been successfully applied to the time / frequency measuring system, atomic frequency standards system, and radar system are described. In addition, the working principle, implementation approach, and the main technical specifications of the frequency synthesizing sources are also given.

Zhou, Liren; Lin, Hai

1994-01-01

355

Effect of a continuous hot water treatment of potato tubers on seed-borne fungal pathogens  

Microsoft Academic Search

Summary  The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive.\\u000a \\u000a Potato tubers were exposed to 55C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated\\u000a seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of

E. P. Dashwood; E. M. Burnett; M. C. M. Perombelon

1991-01-01

356

Using a diverse seed mix to establish native plants on a Sonoran Desert burn  

Microsoft Academic Search

Revegetating burns is a major challenge facing resource managers in the low- and unpredictable-precipitation deserts of the southwestern US. We monitored the effectiveness of using a diverse, 28-species seed mix for establishing native plants on a 1.5-ha (3.7-ac) burn in the northern Sonoran Desert. Our objective was to compare species performances, which we assessed by measuring species frequencies and cover

2009-01-01

357

Meta-analysis of environmental effects on soybean seed composition  

Microsoft Academic Search

The value of commodity soybean depends on the concentration of protein and oil in the seeds. While seed composition is primarily genetically determined, environmental conditions during seed development also affect seed component accumulation, and can result in protein and\\/or oil deficits for processing. To understand the general environmental effects on soybean composition, we conducted a meta-analysis of published data quantifying

José L. Rotundo; Mark E. Westgate

2009-01-01

358

Weed seed predation in organic and conventional fields  

Microsoft Academic Search

Enhanced biological control of weed seeds may improve sustainability of agricultural production. Biological control due to seed predation may be higher in organic fields because organic production generally supports more seed predators. To investigate such a difference, weed seed predation was studied in autumn in eight organic and eight conventional mixed cropping fields in New Zealand. Predation rates were estimated

S. Navntoft; S. D. Wratten; K. Kristensen; P. Esbjerg

2009-01-01

359

HORTSCIENCE 42(6):14361439. 2007. Primed Lettuce Seeds Exhibit  

E-print Network

. Lactuca sativa, seed priming, aging, viability equation, germination Abstract. The Ellis-Roberts seed life. Because primed seeds were not used in developing the Ellis-Roberts equation, the reciprocal Ben' and `Parris Island Cos'. Seeds primed in polyethylene glycol 8000 (­1.45 MPa, 24 h at 15 8C

Bradford, Kent

360

Tomato Tasting Seed Source List 2011 Snyder Farm Observation Trial  

E-print Network

Tomato Tasting Seed Source List 2011 Snyder Farm Observation Trial Seed Source*Tomato Variety Beefsteak/Extra Large Tomato Growers Supply CoAnanas Noir Pinetree Garden SeedsBig Rainbow Tomato Growers Supply CoBoondocks StokesBrandywine Tomato Growers Supply CoChurch Seed Savers Exchange

Goodman, Robert M.

361

Note: Seed for Moreton tomato are available in packets (35 seeds) from http://www.njfarmfresh.rutgers.edu/ JerseyTomato.html. Bulk Moreton seed available from Harris Seed http://www.harrisseeds.com.  

E-print Network

Note: Seed for Moreton tomato are available in packets (35 seeds) from http://www.njfarmfresh.rutgers.edu/ JerseyTomato.html. Bulk Moreton seed available from Harris Seed http://www.harrisseeds.com. Shipping Tomato Point of Purchase Material 2012 Order Form for Retailers Plant labels, 5 X 7 bench cards and sign

Goodman, Robert M.

362

Designing Seeds for Similarity Search in Genomic DNA Jeremy Buhler  

E-print Network

or "seed" of matching bases. The literature suggests that the choice of seed substantially affects are good choices. We also describe Mandala, a software tool for seed design, and show that it can be used or word of matching bases1 . All matching words between two sequences can be found quickly, so seeded

Lonardi, Stefano

363

Semi-supervised Document Clustering with Dual Supervision through Seeding  

E-print Network

, Features Keywords User Supervision, Feature Supervision, Seeding, Text Cloud 1. INTRODUCTION TraditionalSemi-supervised Document Clustering with Dual Supervision through Seeding Yeming Hu Dalhousie labeled features to gen- erate cluster seeds to seed the unsupervised clustering. In this paper, we

Milios, Evangelos E.

364

Report on the Polarimetric Cloud Analysis and Seeding Test 2  

E-print Network

Report on the Polarimetric Cloud Analysis and Seeding Test 2 (POLCAST2 ) David Delene1 , Paul seeding of convective clouds in North Dakota. · Determine identifiable signatures of hygroscopic seeding by aerosol and CCN concentrations. · Characterization of the cloud droplet size distributions for seeded

Delene, David J.

365

7 CFR 201.58a - Indistinguishable seeds.  

Code of Federal Regulations, 2010 CFR

...or determination that seed is hybrid is not possible by seed characteristics...seeds shall be grown on white filter paper and the number of fluorescent...seeds. Place two layers of filter paper in a container and moisten...down, on the two layers of filter paper and cover the...

2010-01-01

366

Seed and spore banks of two boreal mires  

Microsoft Academic Search

The importance of the seed bank as a regenerative strategy in disturbed mires and the viability of seeds and spores in peat stratigraphy on two drained mires were studied prior to restoration. Most of the seedlings developed from the surface sample but still viable seeds occurred in the deepest layer sampled (50 cm). Germination from seeds, however, remained low. Six

Sinikka Jauhiainen

1998-01-01

367

SEED GERMINATION AND VIABILITY OF WYOMING SAGEBRUSH IN NORTHERN NEVADA  

Microsoft Academic Search

SUMMARY Seed size and germination behavior affect performance of early seedlings. The purpose of this study was to investigate rela- tionships between seed size and germination percentage, germina- tion rate, time course of germination and seed viability in Wyo- ming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle and Young). Working hypotheses were: 1) for single seeds, germination percentages and rates

Carlos A. Busso; Mónica Mazzola; Barry L. Perryman

2005-01-01

368

Effects of Fertilisers on Seed Germination in New Zealand  

Microsoft Academic Search

This paper uses data from a series of local field and glasshouse studies to highlight the main issues associated with fertilisers causing germination damage to seed. When fertiliser was placed in close contact with seed either through a conventional drill or when placed on top of seed in the glasshouse, in general small seed was more predisposed to germination damage

M. D. Craighead

369

7 CFR 353.9 - Standards for accreditation of non-government facilities to perform laboratory seed health...  

Code of Federal Regulations, 2013 CFR

...perform laboratory seed health testing and seed crop phytosanitary...Agriculture (Continued) ANIMAL AND PLANT HEALTH INSPECTION...perform laboratory seed health testing and seed crop phytosanitary...perform laboratory seed health testing or seed crop...

2013-01-01

370

7 CFR 353.9 - Standards for accreditation of non-government facilities to perform laboratory seed health...  

Code of Federal Regulations, 2012 CFR

...perform laboratory seed health testing and seed crop phytosanitary...Agriculture (Continued) ANIMAL AND PLANT HEALTH INSPECTION...perform laboratory seed health testing and seed crop phytosanitary...perform laboratory seed health testing or seed crop...

2012-01-01

371

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

372

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. PMID:24086477

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

2013-01-01

373

The roles of seed mass and persistent seed banks in gap colonisation in grassland  

Microsoft Academic Search

Gaps in grassland created by animals are often sites for species regeneration. The persistent seed banks of ant-hills and\\u000a surrounding soils in a calcareous grassland in southern Britain were compared and analysed in terms of seed mass and longevity.\\u000a The relative abundance of species on ant-hills compared to the pasture was highly correlated with seed abundance in ant-hill\\u000a soil. The

Timothy John King

2007-01-01

374

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. ?? 2010 Society for Ecological Restoration International.

DeFalco, L.A.; Esque, T.C.; Nicklas, M.B.; Kane, J.M.

2012-01-01

375

Effect of seed size on protein and lipid contents, germination and imbibition in true potato seeds  

Microsoft Academic Search

Summary  Seeds of an open pollinated crop of potato (Solanum tuberosum L.) TPS-2, cv. Kufri Jyoti, were graded into four sizes. There were significant differences between grades for 100-seed weight,\\u000a the concentrations of total proteins and ethanol soluble proteins, and total lipids and phospholipids.\\u000a \\u000a Large seeds contained higher levels (% dry weight) of total proteins, ethanol soluble proteins and alkali soluble

A. K. Bhatt; T. C. Bhalla; H. O. Agrawal; M. D. Upadhya

1989-01-01

376

Allometric allocation in fruit and seed packaging conditions the conflict among selective pressures on seed size  

Microsoft Academic Search

Selective pressures on seed size could vary among the different stages of plant life cycles, so no simple relation could explain\\u000a a priori its evolution. Here, we determined the relationships between seed size and two fitness components—seed dispersal and survival\\u000a from predation—in a bird-dispersed tree, Crataegus monogyna. We interpret these relationships in relation to the patterns of mass allocation to

Isabel Martínez; Daniel García; José Ramón Obeso

2007-01-01

377

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

378

Precise wavelength control of a single-frequency pulsed Ho:Tm:YLF laser.  

PubMed

We demonstrate wavelength control of a single-frequency diode-pumped Ho:Tm:YLF laser by referencing its wavelength to an absorption line of carbon dioxide. We accomplish this wavelength control by injection seeding with a cw Ho:Tm:YLF laser that can be tuned over or stabilized to carbon dioxide or water vapor lines. We show that the pulsed laser can be scanned precisely over an absorption line of carbon dioxide by scanning the injection seed laser wavelength. We locked the pulsed laser to within 18.5 MHz of the absorption line center by stabilizing the injection seed on the line center. The single-frequency pulsed output, intended for use as a transmitter for differential absorption lidar detection of atmospheric carbon dioxide and water vapor and for coherent detection of wind, is 100 mJ per pulse at a 5-Hz repetition rate. PMID:11921801

Koch, Grady J; Petros, Mulugeta; Yu, Jirong; Singh, Upendra N

2002-03-20

379

Squeezing frequency combs  

E-print Network

We have developed the full theory of a synchronously pumped type I optical parametric oscillator (SPOPO). We derive expressions for the oscillation threshold and the characteristics of the generated mode-locked signal beam. We calculate the output quantum fluctuations of the device, and find that, in the degenerate case (coincident signal and idler set of frequencies), perfect squeezing is obtained when one approaches threshold from below for a well defined "super-mode', or frequency comb, consisting of a coherent linear superposition of signal modes of different frequencies which are resonant in the cavity.

German J. De Valcarcel; Giuseppe Patera; Nicolas Treps; Claude Fabre

2006-05-15

380

Radio frequency strain monitor  

NASA Technical Reports Server (NTRS)

A radio frequency strain monitor includes a voltage controlled oscillator for generating an oscillating signal that is input into a propagation path. The propagation path is preferably bonded to the surface of a structure to be monitored and produces a propagated signal. A phase difference between the oscillating and propagated signals is detected and maintained at a substantially constant value which is preferably a multiple of 90.degree. by changing the frequency of the oscillating signal. Any change in frequency of the oscillating signal provides an indication of strain in the structure to which the propagation path is bonded.

Heyman, Joseph S. (Inventor); Rogowski, Robert S. (Inventor); Holben, Jr., Milford S. (Inventor)

1989-01-01

381

Quantum frequency downconversion experiment  

E-print Network

We report the first quantum frequency downconversion experiment. Using the difference frequency generation process in a periodically poled lithium niobate waveguide, we successfully observed the phase-preserved frequency downconversion of a coherent pulse train with an average photon number per pulse of $<$1, from the 0.7-$\\mu$m visible wavelength band to the 1.3-$\\mu$m telecom band. We expect this technology to become an important tool for flexible photonic quantum networking, including the realization of quantum repeater systems over optical fiber using atom-photon entanglement sources for the visible wavelength bands.

Hiroki Takesue

2010-06-02

382

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

383

Seed Dispersers, Seed Predators, and Browsers Act Synergistically as Biotic Filters in a Mosaic Landscape  

PubMed Central

In this study, we analize the functional influence of animals on the plants they interact with in a mediterranean mountain. We hypothesise that seed dispersers, seed predators, and browsers can act as biotic filters for plant communities. We analyse the combined effects of mutualistic (seed dispersal) and antagonistic (seed predation, herbivory) animal interactions in a mosaic landscape of Mediterranean mountains, basing our results on observational and experimental field. Most of the dispersed seeds came from tree species, whereas the population of saplings was composed predominantly of zoochorous shrub species. Seed predators preferentially consumed seeds from tree species, whereas seeds from the dominant fleshy-fruited shrubs had a higher probability of escaping these predators. The same pattern was repeated among the different landscape units by browsers, since they browsed selectively and far more intensely on tree-species saplings than on the surrounding shrubs. In synthesis, our work identifies the major biotic processes that appear to be favoring a community dominated by shrubs versus trees because seed dispersers, predators, and herbivores together favored shrub dispersal and establishment versus trees. PMID:25233342

Zamora, Regino; Matias, Luis

2014-01-01

384

The functional response of a hoarding seed predator to mast seeding.  

PubMed

Mast seeding involves the episodic and synchronous production of large seed crops by perennial plants. The predator satiation hypothesis proposes that mast seeding maximizes seed escape because seed predators consume a decreasing proportion of available seeds with increasing seed production. However, the seed escape benefits of masting depend not only on whether predators are satiated at high levels of seed production, but also on the shape of their functional response (type II vs. type III), and the actual proportion of available seeds that they consume at different levels of seed production. North American red squirrels (Tamiasciurus hudsonicus) are the primary vertebrate predator of white spruce (Picea glauca) mast seed crops in many boreal regions because they hoard unopened cones in underground locations, preempting the normal sequence of cone opening, seed dispersal, and seed germination. We document the functional response of cone-hoarding by red squirrels across three non-mast years and one mast year by estimating the number of cones present in the territories of individual red squirrels and the proportion of these cones that they hoarded each autumn. Even though red squirrels are not constrained by the ingestive and on-body (fat reserves) energy reserve limitations experienced by animals that consume seeds directly, most squirrels hoarded < 10% of the cones present on their territories under mast conditions. Cone availability during non-mast years also reached levels that satiated the hoarding activity of red squirrels; however, this occurred only on the highest-quality territories. Squirrels switched to mushroom-hoarding when cone production was low and mushrooms were abundant. This resulted in type III functional response whereby the proportional harvest of cones was highest at levels of cone availability that were intermediate within non-mast years. Overall, more cones escaped squirrel cone-hoarding during a mast event than when cone production was low in non-mast years, which supports the predator satiation hypothesis. However, the highly variable seed escape in non-mast years may help to explain why all spruce cone production is not concentrated into fewer, larger, mast years. PMID:20957961

Fletcher, Quinn E; Boutin, Stan; Lane, Jeffrey E; LaMontagne, Jalene M; McAdam, Andrew G; Krebs, Charles J; Humphries, Murray M

2010-09-01

385

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

386

Vacuum Seed Sowing Manifold: a novel device for high-throughput sowing of Arabidopsis seeds.  

PubMed

The small size of Arabidopsis provides both opportunities and difficulties for laboratory research. Large numbers of plants can be grown in a relatively small area making it easy to observe and investigate interesting phenotypes. Conversely, their small size can also make it difficult to obtain large quantities of tissue for investigation using modern molecular techniques. Sowing large numbers of their seed can overcome this; however, their small seed size makes this difficult. Here we present the Vacuum Seed Sowing Manifold (VSSM), a simple device that can be printed using a 3D printer and provides a new high throughput method to sow large numbers of seeds at a range of densities. PMID:24148867

Barker, Richard; Cox, Benjamin; Mackie, Thomas Rockwell; Masson, Patrick

2013-01-01

387

Respiratory Transition during Seed Germination 1  

PubMed Central

Experiments with germinating seeds of Wayne soybean (Glycine max Merr.) show that between the 4th and the 8th hour of germination, respiration experiences a transition from predominantly “alternate” respiration, which is sensitive to salicylhydroxamic acid, to a cyanide-sensitive respiration. The dependence of early germination stages on alternate respiration is reflected in several types of seed functions, including subsequent root growth rate, chlorophyll synthesis, and germination itself. The early period of germination is shown to require a normal O2 tension, which is no longer a requirement at later stages. The changing sensitivity to cyanide and to salicylhydroxamic acid is found to be common to seven different types of germinating seeds. It is proposed that the alternate pathway of respiration provides something essential for the completion of the earliest stages of seed germination. PMID:16659465

Yentur, Semahat; Leopold, A. Carl

1976-01-01

388

Seed train optimization for cell culture.  

PubMed

For the production of biopharmaceuticals a seed train is required to generate an adequate number of cells for inoculation of the production bioreactor. This seed train is time- and cost-intensive but offers potential for optimization. A method and a protocol are described for the seed train mapping, directed modeling without major effort, and its optimization regarding selected optimization criteria such as optimal points in time for cell passaging. Furthermore, the method can also be applied for the set-up of a new seed train, for example for a new cell line. Although the chapter is directed towards suspension cell lines, the method is also generally applicable, e.g. for adherent cell lines. PMID:24297426

Frahm, Björn

2014-01-01

389

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. PMID:21209072

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

2011-01-01

390

Automatic Brachytherapy Seed Placement Under MRI Guidance  

PubMed Central

The paper presents a robotic method of performing low dose rate prostate brachytherapy under magnetic resonance imaging (MRI) guidance. The design and operation of a fully automated MR compatible seed injector is presented. This is used with the MrBot robot for transperineal percutaneous prostate access. A new image-registration marker and algorithms are also presented. The system is integrated and tested with a 3T MRI scanner. Tests compare three different registration methods, assess the precision of performing automated seed deployment, and use the seeds to assess the accuracy of needle targeting under image guidance. Under the ideal conditions of the in vitro experiments, results show outstanding image-guided needle and seed placement accuracy. PMID:17694871

Patriciu, Alexandru; Petrisor, Doru; Muntener, Michael; Mazilu, Dumitru; Schar, Michael; Stoianovici, Dan

2011-01-01

391

Plant Science Inquiry: From Seed to Flower  

NSDL National Science Digital Library

This activity is a first grade life science activity where the students practice inquiry skills by developing questions about seeds, planting them and noting details about how they change as they grow.

Wheeler, Elizebeth

392

Inhibitory effect of myrigalone A on seed germination 1 Myrigalone A inhibits Lepidium sativum seed germination by interference with  

E-print Network

Inhibitory effect of myrigalone A on seed germination 1 Myrigalone A inhibits Lepidium sativum seed germination by interference with gibberellin metabolism and apoplastic superoxide production required Issue on Seed Biology (Issue 1, 2012) Supplementary data #12;Inhibitory effect of myrigalone A on seed

Leubner, Gerhard

393

A seed bank pathogen causes seedborne disease: Pyrenophora semeniperda on undispersed grass seeds in western North America  

Microsoft Academic Search

The generalist pathogen Pyrenophora semeniperda is abundant in seed banks of the exotic winter annual grass Bromus tectorum in semiarid western North America and is also found in the seed banks of co-occurring native grasses. In this study, we examined natural incidence of disease caused by this pathogen on undispersed host seeds, that is, seeds that were never directly exposed

Susan E. Meyer; Julie Beckstead; Phil S. Allen; Duane C. Smith

2008-01-01

394

Evaluation of water binding, seed coat permeability and germination characteristics of wheat seeds equilibrated at different relative humidities  

Microsoft Academic Search

The relative binding of seed water and seed coat membrane stability were measured in two contrasting wheat ( Triticum aestivum L) varieties, HDR 77 (drought-tolerant) and HD 2009 (susceptible) using seed water sorption isotherms, electrical conductivity (EC) of leachates and desorption-absorption isotherms. Analysis of sorption isotherm at 25°C showed that the seeds of HDR 77 had significantly higher number of

Nabamita Chatterjee; Shantha Nagarajan

395

Seedling emergence, growth, and allocation of Oriental bittersweet: effects of seed input, seed bank, and forest floor litter  

Microsoft Academic Search

The establishment of invasive plant populations is controlled by seed input, survival in the soil seed bank, and effects of soil surface disturbance on emergence, growth, and survival. We studied the invasive vine Celastrus orbiculatus Thunb. (Oriental bittersweet) to determine if seedlings in forest understory germinate from the seed bank or from seed rain. We also conducted a greenhouse experiment

Joshua W. Ellsworth; Robin A. Harrington; James H. Fownes

2004-01-01

396

Effect of potassium, zinc and phosphorus on seed yield, seed viability and seedling vigor of cotton (Gossypium barbadense L.)  

Microsoft Academic Search

Conditions prevailing during seed formation can affect the quality of seed produced, and hence crop establishment in the next growing season. Two field experiments were conducted to investigate the effect of potassium, zinc and phosphorus on seed yield, seed viability, and seedling vigor of cotton cv. Giza 86. Fertilizer applications occurred as follows: two rates of potassium (0.0 and 47 kg

Zakaria M. Sawan; Ashraf H. Fahmy; Serag E. Yousef

2011-01-01

397

Landscape-scale eco-evolutionary dynamics: selection by seed predators and fire determine a major reproductive strategy.  

PubMed

Recent work in model systems has demonstrated significant effects of rapid evolutionary change on ecological processes (eco-evolutionary dynamics). Fewer studies have addressed whether eco-evolutionary dynamics structure natural ecosystems. We investigated variation in the frequency of serotiny in lodgepole pine (Pinus contorta), a widespread species in which postfire seedling density and ecosystem structure are largely determined by serotiny. Serotiny, the retention of mature seeds in cones in a canopy seed bank, is thought to be an adaptation for stand-replacing fire, but less attention has been paid to the potential selective effects of seed predation on serotiny. We hypothesized that spatial variation in percentage serotiny in lodgepole pine forests results from an eco-evolutionary dynamic where the local level of serotiny depends on the relative strengths of conflicting directional selection from fire (favoring serotiny) and seed predation (favoring cones that open at maturity). We measured percentage serotiny, the abundance of American red squirrels (Tamiasciurus hudsonicus; the primary pre-dispersal seed predator of lodgepole pine), and several measures of forest structure in Yellowstone National Park, USA. Fire frequency strongly predicted the frequency of serotiny, a pattern that is well-supported in the literature. At sites with high fire frequency (return intervals of -135-185 years) where fire favors increased serotiny, squirrel abundance was negatively associated with serotiny, suggesting that selection from predation can overwhelm selection from fire when squirrels are abundant. At sites with low fire frequency (return intervals of -280-310 years), serotiny was nearly universally uncommon (< 10%). Finally, forest structure strongly predicted squirrel density independently of serotiny, and serotiny provided no additional explanatory power, suggesting that the correlation is caused by selection against serotiny exerted by squirrels, rather than squirrels responding to variation in percentage serotiny. PMID:23923494

Talluto, Matt V; Benkman, Craig W

2013-06-01

398

Seed Rain of Restored and Natural Prairie Wetlands  

Microsoft Academic Search

In prairie wetland restorations, seeds may be limiting plant recolonization but this has never been quantified in the field.\\u000a We evaluated the seed rain in restored and natural wetlands to determine if seed limitation constrains plant recolonization.\\u000a We were particularly interested in determining whether Carex species, dominant vegetation of seasonally flooded zones, are seed limited in restorations. We quantified seed

Karin M. Kettenring; Susan M. Galatowitsch

2011-01-01

399

Respiration in dormant and non-dormant bitterbrush seeds  

Microsoft Academic Search

Bitterbrush (Purshia tridentata dc.) seed dormancy is not understood but may result from a metabolic block by a chemical inhibitor. To determine whether dormancy affects seed respiration, we compared CO2evolution from individual imbibed dormant and non-dormant seeds and from germinating seeds, using Fourier transform infrared photoacoustic spectroscopy. We found CO2evolution did not differ between dormant and non-dormant seeds, and that

D. T. Booth; S. Sowa

2001-01-01

400

Germination of 151-year old Acacia spp. seeds  

Microsoft Academic Search

A collection of seeds from five Acacia species was made in Egypt in 1856. Since then, the seeds have been stored at room temperature in different Swedish museums.\\u000a Due to the extreme longevity within the seeds of Acacia and related species, germination tests were performed on the now 151-year old seed. Seeds of two of the five species tested\\u000a germinated.

Matti W. Leino; Johan Edqvist

2010-01-01

401

A fast 3D seed-filling algorithm  

Microsoft Academic Search

The 3D seed-filling algorithm that fills consecutive object voxels at a time has shown higher efficiency than the method of filling only one voxel at a time. However, it searches seeds for filled voxels already containing no seeds. This paper presents a fast 3D seed-filling algorithm that uses a 2D pointer array of linked lists to avoid the redundant seed

Shyan-bin Jou; Ming-dar Tsai

2003-01-01

402

Factors causing losses of clover seed  

Microsoft Academic Search

Crops of white clover (Trifolium repens L.), alsike clover (Trifolium hybridum L.), and red clover (Trifolium pratense L.) were studied during 1958–60 to determine the effect of shrivelling, insect damage, and harvesting operations on seed yields.In individual crops the percentages of shrivelled seed ranged from 1–28 per cent in white clover, 1–44 per cent in alsike clover, and 23–54 per

I. W. Forster; G. L. Jeffery; T. Palmer-Jones

1962-01-01

403

Amino acid composition of Lesquerella seed meals  

Microsoft Academic Search

Seed meals from 14 species ofLesquerella, family Cruciferae, were analyzed for 18 amino acids. Lysine and methionine contents ranged, respectively, from 331 to 440,\\u000a and 72 to 94 mg. per g. of nitrogen. When compared with 9 species ofBrassica (rape, mustard),Lesquerella seeds were higher in lysine and lower in methionine. Thirteen unidentified substances were detected by the ion-exchange chromatographic\\u000a method

Roger Wayne Miller; C. H. Van Etten; I. A. Wolff

1962-01-01

404

Promotion of Seed Germination by Cyanide  

PubMed Central

Potassium cyanide at 3 ?m to 10 mm promotes germination of Amaranthus albus, Lactuca sativa, and Lepidium virginicum seeds. l-Cysteine hydrogen sulfide lyase, which catalyzes the reaction of HCN with l-cysteine to form ?-l cyanoalanine, is active in the seeds. ?-l-Cyanoalanine is the most effective of the 23 ?-amino acids tested for promoting germination of A. albus seeds. Aspartate, which is produced by enzymatic hydrolysis of asparagine formed by hydrolysis from ?-cyanoalanine, is the second most effective of the 23 amino acids. Uptake of aspartate-4-14C is much lower than of cyanide. Radioactive tracer in K14CN shows uptake of about 1.5 ?moles of HCN per gram of A. albus and L. sativa seeds after 20 hours of imbibition. Extracts of the seeds gave high 14C activity in ?-cyanoalanine, asparagine, and aspartate. The acid-hydrolyzed protein extract gave high activity only in aspartate. Tests were negative for free cyanide in the seed. Respiration of the seed is inhibited more than 75% by KCN and by KN3 at 10 mm. Azide at greater than 1.0 mm inhibits the promotion of germination by cyanides. Neither 0.1 mm KCN nor KN3 inhibit O2 consumption, whereas lower concentrations promote germination. It is concluded that the high rate of utilization of cyanide in the reaction to form ?-l-cyanoalanine and the subsequent incorporation into protein limit any inhibition of oxygen consumption. The promotion of seed germination is substrate-limited by asparagine-aspartate, which is required for protein synthesis. PMID:16658492

Taylorson, R. B.; Hendricks, S. B.

1973-01-01

405

Promotion of seed germination by cyanide.  

PubMed

Potassium cyanide at 3 mum to 10 mm promotes germination of Amaranthus albus, Lactuca sativa, and Lepidium virginicum seeds. l-Cysteine hydrogen sulfide lyase, which catalyzes the reaction of HCN with l-cysteine to form beta-l cyanoalanine, is active in the seeds. beta-l-Cyanoalanine is the most effective of the 23 alpha-amino acids tested for promoting germination of A. albus seeds. Aspartate, which is produced by enzymatic hydrolysis of asparagine formed by hydrolysis from beta-cyanoalanine, is the second most effective of the 23 amino acids. Uptake of aspartate-4-(14)C is much lower than of cyanide.Radioactive tracer in K(14)CN shows uptake of about 1.5 mumoles of HCN per gram of A. albus and L. sativa seeds after 20 hours of imbibition. Extracts of the seeds gave high (14)C activity in beta-cyanoalanine, asparagine, and aspartate. The acid-hydrolyzed protein extract gave high activity only in aspartate. Tests were negative for free cyanide in the seed. Respiration of the seed is inhibited more than 75% by KCN and by KN(3) at 10 mm. Azide at greater than 1.0 mm inhibits the promotion of germination by cyanides. Neither 0.1 mm KCN nor KN(3) inhibit O(2) consumption, whereas lower concentrations promote germination. It is concluded that the high rate of utilization of cyanide in the reaction to form beta-l-cyanoalanine and the subsequent incorporation into protein limit any inhibition of oxygen consumption. The promotion of seed germination is substrate-limited by asparagine-aspartate, which is required for protein synthesis. PMID:16658492

Taylorson, R B; Hendricks, S B

1973-07-01

406

Azospirillum inoculation in pregerminating wheat seeds  

Microsoft Academic Search

Azospirillum cells were inoculated in pregerminating wheat during seed imbibition. Surface-sterilized seeds of Triticum aestivum cv. Buck Pucara were sequentially soaked for 3 h in water and 3 h in the inoculum of 3 x lo8 Azospirillum brasilense Sp 245 cells. rnL-I, to allow bacteria to enter during imbibition. Germination and seedling growth were accomplished in sterile distilled water at

Cecilia M. Creus; Rolando J. Sueldo; Carlos A. Barassi

1996-01-01

407

Proteomics of Arabidopsis seed germination and priming  

Microsoft Academic Search

To better understand seed germination, a complex developmental process, we developed a proteome analysis of the model plant Arabidopsis for which complete genome sequence is now available. Among about 1,300 total seed proteins resolved in two-dimensional gels, changes in the abundance (up- and down-regulation) of 74 proteins were observed during germination sensu stricto (i.e. prior to radicle emergence) and the

K. Gallardo; C. Job; S. P. C. Groot; M. Puype; H. Demol; J. Vandekerckhove; D. Job

2003-01-01

408

Lignans in seeds of Linum species.  

PubMed

Mature seeds of 20 Linum species were analyzed for their content of lignans. The seeds of common flax (Linum usitatissimum L.) are known to contain as characteristic lignan sesoisolariciresinol diglucoside (SDG), whose presence in seeds of some other Linum species has also been reported. In order to investigate the material for the presence of such very polar lignans as well as for less polar non-glycosidic lignans as frequently found in aerial parts of Linum species, polar and non-polar extracts of each sample were analyzed by HPLC/ESI-MSMS. SDG was detected in 15 of 16 investigated seed samples of taxa representing sections Linum and Dasylinum. None of eight samples of taxa from sections Syllinum and Linopsis contained detectable amounts of SDG. Quite interestingly, most of the SDG-positive samples contained the 8R,8'R-isomer exclusively while only three (including L. usitatissimum) contained the 8S,8'S-stereoisomer as the predominant form. As a most noteworthy finding, the dichloromethane extracts obtained from seeds of several Linum species were found to contain significant concentrations of non-polar cyclolignans of the arylnaphthalene/-dihydronaphthalene lactone type or, alternatively of the aryltetralin lactone type. Thus, seeds of Linum perenne L. as well as those of several other representatives of sections Linum and Dasylinum were found to contain significant concentrations of the arylnaphthalene justicidin B along with further compounds of this type and some aryldihydronaphthalene-type lignans. On the other hand, seeds of Linum flavum and further representatives of section Syllinum were found to contain aryltetralin-type lignans, mainly in the form of esters with aliphatic carboxylic acids, such as 6-methoxypodophyllotoxin-7-O-n-hexanoate, whose occurrence in L. flavum seeds has very recently been reported by us for the first time. Various chemosystematic and biogenetic aspects are discussed in the light of these results. PMID:22854497

Schmidt, Thomas J; Klaes, Michael; Sendker, Jandirk

2012-10-01

409

Canopy seed storage in woody plants  

Microsoft Academic Search

The retention of seeds in the plant canopy for one to 30 years or more is termed serotiny. It is well represented floristically\\u000a and physiognomically in fire-prone, nutrient-poor and seasonally-dry sclerophyll vegetation in Australia, and to a lesser\\u000a extent, South Africa followed by North America. While the seed-storing structures vary greatly, all will release their propagules\\u000a following exposure to the

Byron B. Lamont; D. C. Le Maitre; R. M. Cowling; N. J. Enright

1991-01-01

410

Some Physical Properties of Hemp Seed  

Microsoft Academic Search

Various physical properties of hemp seed were determined as a function of moisture content. As the moisture content increased from 8·62 to 20·88% dry basis (d.b.), the dimensions of the major, medium and minor axes varied from 3·79 to 4·11mm, 2·92 to 3·11mm and 2·47 to 2·82mm, respectively. In the same moisture range, studies on rewetted hemp seed showed that

K. Sacilik; R. Öztürk; R. Keskin

2003-01-01

411

Some Physical Properties of Locust Bean Seed  

Microsoft Academic Search

To design equipment and facilities to process “Iru”, an important food-flavouring condiment made from locust bean seeds, some of the physical properties of the seeds were determined. At a moisture content of 6·42% d.b., the average length, width and thickness of locust bean were 10·80, 8·42 and 4·64 mm, respectively. The average geometric mean diameter, sphericity and density were 7·47

J. O. Olajide; B. I. O. Ade-Omowaye

1999-01-01

412

Effects of Cloud Seeding in West Texas  

Microsoft Academic Search

The effect of randomized seeding with droppable silver iodide (AgI) flares in West Texas during the Southwest Cooperative Program is addressed. Attention is focused on individual convective cells and on the small mesoscale convective clusters that contain the cells.Analysis of three-dimensional, volume-scan, C-band radar data using sophisticated tracking software indicates that AgI seeding increased the areas, durations and rain volumes

Daniel Rosenfeld; William L. Woodley

1989-01-01

413

Seed germination characteristics of Halogeton glomeratus  

Microsoft Academic Search

Halogeton glomeratus (Bieb.) C.A. Mey, an annual forb in the family Chenopodiaceae, is widely distributed in the inland salt deserts of western North America. Experiments were conducted to determine the effects of NaCl and temperature on seed germination and the recovery of germination responses after transfer to distilled water. Seeds of H. glomeratus were germinated at various temperature regimes (5-15°C,

M. Ajmal Khan; Bilquees Gul; Darrell J. Weber

2001-01-01

414

Laser Heater and seeded Free Electron Laser  

E-print Network

In this paper we consider the effect of laser heater on a seeded Free Electron Laser. We develop a model embedding the effect of the energy modulation induced by the heater with those due to the seeding. The present analysis is compatible with the experimental results obtained at FERMI displaying secondary maxima with increasing heater intensity. The treatment developed in the paper confirms and extends previous analyses and put in evidence further effects which can be tested in future experiments.

Dattoli, G; Sabia, E

2014-01-01

415

Graphene Frequency Multipliers  

E-print Network

In this letter, the ambipolar transport properties of graphene flakes have been used to fabricate full-wave signal rectifiers and frequency-doubling devices. By correctly biasing an ambipolar graphene field-effect transistor ...

Wang, Han

416

Plants grow better if seeds see green  

NASA Astrophysics Data System (ADS)

We report on the response of dry plant seeds to their irradiation with intense green light applied at biostimulatory doses. Red and near-infrared light delivered by lasers or arrays of light emitting diodes applied at such doses have been shown previously by us to have effects on mammalian cells. Effects include cell proliferation and elevation of cell vitality, and have practical applications in various biomedical fields. Growth processes induced by photoreceptor stimulation (phytochromes and cryptochromes) in plant seeds with green light were described so far only for imbibed seeds. In this paper, we show that irradiation of dry cress, radish and carrot seeds with intense green light (laser or arrays of light emitting diodes), applied at biostimulatory doses, resulted in a significant increase in biomass—14, 26, and 71 days after seeding, respectively. In the case of radish and carrot, the irradiation led to important changes in the root-to-foliage surface ratio. Seeds with a potential to grant growth acceleration could be of special interest in agricultural applications, and could even compensate for shorter growth seasons caused by climate change.

Sommer, Andrei P.; Franke, Ralf-Peter

2006-07-01

417

Survival of seeds in hypervelocity impacts  

NASA Astrophysics Data System (ADS)

Panspermia (‘seeds everywhere’) postulates that life naturally migrates through space. Laboratory studies of Panspermia often examine the survival of Earth's species under the conditions thought to occur during transfer through space. Much of this research has centred on bacteria, but here we consider seeds themselves. We simulated the extreme accelerations necessary for their hypothetical ejection from a planetary surface and the impacts associated with their arrival on another planet. Seeds of tobacco, alfalfa and cress were fired into water at speeds in the range 1 3 km s-1, corresponding to impact shock pressures of circa 0.24 2.4 GPa. No seeds remained intact and able to germinate, even at the lowest speeds. Although fragmentation occurred, even at 3 km s-1 the size of some of the fragments was about 25% that of the seeds. Thus, whilst the seeds themselves did not survive extreme shocks, a substantial fraction of their mass did and might successfully deliver complex organic materials after impact. These results are discussed with respect to ancient Panspermia and the potential of contemporary impacts to eject living organisms into space.

Jerling, Aaron; Burchell, Mark J.; Tepfer, David

2008-10-01

418

Nutritional evaluation of some Nigerian wild seeds.  

PubMed

Some wild seeds, namely Parkia biglobosa, Tetracarpidum conophorum, Pentaclethra macrophylla, Irvingia gabonensis, Afzelia africana, Prosporis africana and Monodora myristica, were randomly collected from various parts of Nigeria and analyzed with regard to their proximate, mineral, antinutrient composition and zinc bioavailability. The results revealed that the seeds had high protein (6.5-24.2%), fat (19.0-58.5%), mineral (Mg, Fe, Zn, Mn, Ca, Na, K, P) and phytate (1043.6-2905.2 mg/100 g) contents, while the cyanide content was low (3.7-6.4 mg/kg). However, Co, Pb and Ni were not detected in all the samples. The calculated [Ca] [phytate]/[Zn] molar ratios (which is the best index for predicting Zn bioavailability) for all the seeds revealed that Parkia biglobosa, Irvingia gabonensis and Prosporis africana had a calculated molar ratio above 0.50 mol/kg (critical level), thus indicating reduced bioavailability of Zn to a critical level. In view of the high fat, protein, mineral and low cyanide contents, the high phytate content would not be expected to reduce bioavailability of Zn in some of the wild seeds (Afzelia africana, Pentaclethra macrophylla and Monodora myristica). These wild seeds could be good nutrient sources if integrated fully into human and animal nutrition. However, further studies will be carried out on the protein quality and toxicological potentials of these wild seeds. PMID:15146961

Oboh, Ganiyu; Ekperigin, M Mofoluso

2004-04-01

419

Density measurement in air with a saturable absorbing seed gas  

NASA Technical Reports Server (NTRS)

A method for making density measurements in a compressible flow by using off resonance laser induced fluorescence is studied. The seed molecule chosen for study is the iodine molecule which is excited with the 514.5 nm line of the argon ion laser whose output is frequency tuned, by as much as 3 GHz, relative to a strong iodine transition using an intracavity etalon. The theory which was developed to analyze the effect will be used in conjunction with two experiments being conducted to further study the method an acoustic resonance tube in which controlled perturbations about a uniform state are produced, and a small supersonic jet in which the conditions of the flow vary widely from point to point.

Baganoff, D.

1982-01-01

420

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

421

A digital frequency synthesizer  

Microsoft Academic Search

A digital frequency synthesizer has been designed and constructed based on generating digital samples ofexp [j(2^{pi}nk\\/N)]at timenT. The real and imaginary parts of this exponential form samples of quadrature sinusoids where the frequency indexkis allowed to vary(-N\\/4) leq K < (N\\/4). The digital samples drive digital to analog converters followed by low-pass interpolating filters to produce analog sinusoids. The method

JOSEPH TIERNEY; CHARLES M. RADER; B. Gold

1971-01-01

422

Metamaterials at zero frequency.  

PubMed

We investigate the problem of designing metamaterial structures which operate at very low frequencies. As an example, we consider the case of a DC magnetic cloak, which requires a variable, anisotropic magnetic permeability with both paramagnetic and diamagnetic components. We show that a structure based on superconducting components is the key to diamagnetism at low frequencies, and present a metamaterial design which meets the requirements of the cloak. PMID:22251595

Wood, B; Pendry, J B

2007-02-21

423

Frequency domain measurement systems  

NASA Technical Reports Server (NTRS)

Stable frequency sources and signal processing blocks were characterized by their noise spectra, both discrete and random, in the frequency domain. Conventional measures are outlined, and systems for performing the measurements are described. Broad coverage of system configurations which were found useful is given. Their functioning and areas of application are discussed briefly. Particular attention is given to some of the potential error sources in the measurement procedures, system configurations, double-balanced-mixer-phase-detectors, and application of measuring instruments.

Eischer, M. C.

1978-01-01

424

Seed provisioning in gynodioeciousSilene acaulis (Caryophyllaceae).  

PubMed

In gynodioecious species, which contain females and hermaphrodites, the outcrossed seeds of females have been found to outperform the outcrossed seeds of hermaphrodites, in spite of the fact that their seeds are not larger in mass. Females do not make pollen. Hence the nutrients that hermaphrodites allocate to pollen, such as nitrogen, might be allocated to seeds by the females, such that individual seeds from females are better provisioned than those from hermaphrodites. Alternatively, females might make more seeds, rather than better provisioned seeds. We tested the hypothesis that seeds from females would be better provisioned for the gynodioecious species Silene acaulis, by comparing seed mass, embryo/endosperm mass, nitrogen and phosphorus content, and energy content for outcrossed seeds from females and hermaphrodites produced in a natural population. We also measured the proportion of flowers that set fruit in both morphs. Seeds from the two sexual morphs were not found to differ significantly for any of the measures of seed provisioning, with seeds from females containing either nonsignificantly less or equivalent amounts of each of the measures as compared to hermaphrodites. However, females set a significantly higher proportion of their flowers to fruit, as compared to hermaphrodites. These results indicate that females do not provision individual seeds more than hermaphrodites in S. acaulis, and alternative hypotheses will need to be examined to explain the difference in the performance of the seeds from the two sexual morphs. PMID:21680354

Delph, L F; Bailey, M F; Marr, D L

1999-01-01

425

Uncoupling the Effects of Seed Predation and Seed Dispersal by Granivorous Ants on Plant Population Dynamics  

PubMed Central

Secondary seed dispersal is an important plant-animal interaction, which is central to understanding plant population and community dynamics. Very little information is still available on the effects of dispersal on plant demography and, particularly, for ant-seed dispersal interactions. As many other interactions, seed dispersal by animals involves costs (seed predation) and benefits (seed dispersal), the balance of which determines the outcome of the interaction. Separate quantification of each of them is essential in order to understand the effects of this interaction. To address this issue, we have successfully separated and analyzed the costs and benefits of seed dispersal by seed-harvesting ants on the plant population dynamics of three shrub species with different traits. To that aim a stochastic, spatially-explicit individually-based simulation model has been implemented based on actual data sets. The results from our simulation model agree with theoretical models of plant response dependent on seed dispersal, for one plant species, and ant-mediated seed predation, for another one. In these cases, model predictions were close to the observed values at field. Nonetheless, these ecological processes did not affect in anyway a third species, for which the model predictions were far from the observed values. This indicates that the balance between costs and benefits associated to secondary seed dispersal is clearly related to specific traits. This study is one of the first works that analyze tradeoffs of secondary seed dispersal on plant population dynamics, by disentangling the effects of related costs and benefits. We suggest analyzing the effects of interactions on population dynamics as opposed to merely analyzing the partners and their interaction strength. PMID:22880125

Arnan, Xavier; Molowny-Horas, Roberto; Rodrigo, Anselm; Retana, Javier

2012-01-01

426

Effects of previous cropping on seed yield and yield components of oil-seed rape ( Brassica napus L.)  

Microsoft Academic Search

Information about the effect of the preceding crop or crop combination on the seed yield of oil-seed rape is extremely scarce. Experiments were carried out in northwest Germany to investigate the effect of different preceding crops on the growth, seed yield and yield components of oil-seed rape. The two directly preceding crops, wheat and oil-seed rape, had only a negligible

Klaus Sieling; Olaf Christen; Bahadour Nemati; Herbert Hanus

1997-01-01

427

The maintenance of mitochondrial genetic variation by negative frequency-dependent selection.  

PubMed

Mitochondrial genes generally show high levels of standing genetic variation, which is puzzling given the accumulating evidence for phenotypic effects of mitochondrial genetic variation. Negative frequency-dependent selection, where the relative fitness of a genotype is inversely related to its frequency in a population, provides a potent and potentially general process that can maintain mitochondrial polymorphism. We assessed the change in mitochondrial haplotype frequencies over 10 generations of experimental evolution in 180 seed beetle populations in the laboratory, where haplotypes competed for propagation to subsequent generations. We found that haplotypes consistently increased in frequency when they were initially rare and decreased in frequency when initially common. Our results have important implications for the use of mtDNA haplotype frequency data to infer population level processes and they revive the general hypothesis that negative frequency-dependent selection, presumably caused by habitat heterogeneity, may commonly promote polymorphism in ecologically relevant life history genes. PMID:24134428

Kazanc?o?lu, Erem; Arnqvist, Göran

2014-01-01

428

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

429

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

430

Poachers Alter Mammal Abundance, Seed Dispersal, and Seed Predation in a Neotropical Forest  

Microsoft Academic Search

We evaluated the hypothesis that poachers reduce the abundance of herbivorous mammals, and that this, in turn, alters seed dispersal, seed predation, and seedling recruitment for two palms ( Attalea bu- tyraceae and Astrocaryum standleyanum ) in central Panama. Using physical evidence left by poachers and in- terviews with forest guards, we quantified poaching intensity for eight forest sites. We

S. Joseph Wright; Horacio Zeballos; Iván Domínguez; Marina M. Gallardo; Marta C. Moreno; Roberto Ibáñez

2000-01-01

431

Seed Coat Microsculpturing Changes during Seed Development in Diploid and Amphidiploid Brassica Species  

PubMed Central

• Background and Aims Seed coat morphology is known to be an excellent character for taxonomic and evolutionary studies, thus understanding its structure and development has been an important goal for biologists. This research aimed to identify the developmental differences of seed coats between amphidiploids and their putative parents in Brassica. • Methods Scanning electron microscope (SEM) studies were carried out on six species (12 accessions), three amphidiploids and their three diploid parents. • Key Results Twelve types of basic ornamentation patterns were recognized during the whole developmental process of the seed coat. Six types of seed coat patterns appeared in three accessions of Brassica rapa, five types in B. oleracea, B. nigra and B. carinata, seven types in B. napus, and eight types in B. juncea. There was less difference among seed coat patterns of the three accessions of B. rapa. The reticulate and blister types were two of the most common patterns during the development of seeds in the six species, the blister?pimple and the pimple?foveate patterns were characteristic of B. rapa, and the ruminate of B. oleracea and B. nigra. The development of seed coat pattern in amphidiploids varied complicatedly. Some accessions showed intermediate patterns between the two putative parents, while others resembled only one of the two parents. • Conclusions The variation in the patterns of seed coat development could be used to provide a new and more effective way to analyse the close relationship among amphidiploids and their ancestral parents. PMID:15037452

ZENG, CHANG?LI; WANG, JIAN?BO; LIU, AI?HUA; WU, XIAO?MING

2004-01-01

432

Inflow of seeds through the forest edge: evidence from seed bank and vegetation patterns  

Microsoft Academic Search

To determine the influence of the proximity of a forest edge on seed bank composition and diversity, we performed a seed bank sampling at ancient deciduous forests bordering intensive arable fields. Also vegetation patterns were taken into account. We hypothised that forest edges may facilitate the entrance of diaspores of invasive species into the forest and the successive incorporation of

Rebecca Devlaeminck; Beatrijs Bossuyt; Martin Hermy

2005-01-01

433

SEED PREDATION AND SELECTION EXERTED BY A SEED PREDATOR INFLUENCE SUBALPINE TREE DENSITIES  

Microsoft Academic Search

Strongly interacting species often have pronounced direct and indirect effects on other species. Here we focus of the effects of pine squirrels (Tamiasciurus spp.), which are a dominant pre-dispersal seed predator of many conifers including limber pines (Pinus flexilis) and whitebark pines (P. albicaulis). Pine squirrels depress seed abundance by harvesting most limber and whitebark pine cones on their territories.

Adam M. Siepielski; Craig W. Benkman

2008-01-01

434

Seed predation and selection exerted by a seed predator influence subalpine tree densities.  

PubMed

Strongly interacting species often have pronounced direct and indirect effects on other species. Here we focus of the effects of pine squirrels (Tamiasciurus spp.), which are a dominant pre-dispersal seed predator of many conifers including limber pines (Pinus flexilis) and whitebark pines (P. albicaulis). Pine squirrels depress seed abundance by harvesting most limber and whitebark pine cones on their territories. Pine squirrels further reduce seed availability for Clark's Nutcrackers (Nucifraga columbiana), the primary seed disperser of these pines, because selection exerted by pine squirrels has reduced the number of seeds per cone and causes seeds to be less accessible. We predicted that, if fewer seeds were available for dispersal by nutcrackers, pine recruitment should be suppressed in areas with pine squirrels. In support of this prediction, stand densities were about two times greater in areas where pine squirrels are absent than in areas where they are present. Alternative explanations that we considered do not account for these differences; however, precipitation may limit stand densities in the absence of seed limitation by pine squirrels. In sum, pine squirrels apparently depress limber and whitebark pine stand densities, with the potential for ecosystem impacts because these pines are foundation species within Western subalpine ecosystems. PMID:18959333

Siepielski, Adam M; Benkman, Craig W

2008-10-01

435

The effect of parsley seed hydration treatment and pelleting on seed vigour  

Microsoft Academic Search

The effect of two priming techniques: hardening (prehydration treatment) and solid matrix priming (SMP) was studied on the seeds of two parsley varieties (Cukrowa and Berli?ska) in 3-year laboratory experiments. On the images obtained from scanning electron microscope (SEM) there is a parsley embryo developing during germination up to the moment of radicle emergence. On the surface of primed seeds,

S. Podlaski; Z. Chrobak; Z. Wyszkowska

436

Proteome profiling of flax (Linum usitatissimum) seed: characterization of functional metabolic pathways operating during seed development.  

PubMed

Flax (Linum usitatissimum L.) seeds are an important source of food and feed due to the presence of various health promoting compounds, making it a nutritionally and economically important plant. An in-depth analysis of the proteome of developing flax seed is expected to provide significant information with respect to the regulation and accumulation of such storage compounds. Therefore, a proteomic analysis of seven seed developmental stages (4, 8, 12, 16, 22, 30, and 48 days after anthesis) in a flax variety, NL-97 was carried out using a combination of 1D-SDS-PAGE and LC-MSE methods. A total 1716 proteins were identified and their functional annotation revealed that a majority of them were involved in primary metabolism, protein destination, storage and energy. Three carbon assimilatory pathways appeared to operate in flax seeds. Reverse transcription quantitative PCR of selected 19 genes was carried out to understand their roles during seed development. Besides storage proteins, methionine synthase, RuBisCO and S-adenosylmethionine synthetase were highly expressed transcripts, highlighting their importance in flax seed development. Further, the identified proteins were mapped onto developmental seed specific expressed sequence tag (EST) libraries of flax to obtain transcriptional evidence and 81% of them had detectable expression at the mRNA level. This study provides new insights into the complex seed developmental processes operating in flax. PMID:23153172

Barvkar, Vitthal T; Pardeshi, Varsha C; Kale, Sandip M; Kadoo, Narendra Y; Giri, Ashok P; Gupta, Vidya S

2012-12-01

437

Promoting smallholder seed enterprises: quality seed production of rice, maize, sorghum and millet in northern Cameroon  

Microsoft Academic Search

Food and Agriculture Organization of the United Nations (FAO) conducted two projects in Cameroon on strengthening rice, and sorghum, maize and millet seed production by smallholder seed enterprises (SSEs). Farmer groups (respectively, 25 SSEs and 114 SSEs) were formed or strengthened and trained. Sixty-six selected lead farmers were trained on the administering and managing of revolving funds. The groups were

Robert G. Guei; Abdoulaye Barra; Drissa Silué

2011-01-01

438

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

439

Frequency Standards and Metrology  

NASA Astrophysics Data System (ADS)

Preface / Lute Maleki -- Symposium history / Jacques Vanier -- Symposium photos -- pt. I. Fundamental physics. Variation of fundamental constants from the big bang to atomic clocks: theory and observations (Invited) / V. V. Flambaum and J. C. Berengut. Alpha-dot or not: comparison of two single atom optical clocks (Invited) / T. Rosenband ... [et al.]. Variation of the fine-structure constant and laser cooling of atomic dysprosium (Invited) / N. A. Leefer ... [et al.]. Measurement of short range forces using cold atoms (Invited) / F. Pereira Dos Santos ... [et al.]. Atom interferometry experiments in fundamental physics (Invited) / S. W. Chiow ... [et al.]. Space science applications of frequency standards and metrology (Invited) / M. Tinto -- pt. II. Frequency & metrology. Quantum metrology with lattice-confined ultracold Sr atoms (Invited) / A. D. Ludlow ... [et al.]. LNE-SYRTE clock ensemble: new [symbol]Rb hyperfine frequency measurement - spectroscopy of [symbol]Hg optical clock transition (Invited) / M. Petersen ... [et al.]. Precise measurements of S-wave scattering phase shifts with a juggling atomic clock (Invited) / S. Gensemer ... [et al.]. Absolute frequency measurement of the [symbol] clock transition (Invited) / M. Chwalla ... [et al.]. The semiclassical stochastic-field/atom interaction problem (Invited) / J. Camparo. Phase and frequency noise metrology (Invited) / E. Rubiola ... [et al.]. Optical spectroscopy of atomic hydrogen for an improved determination of the Rydberg constant / J. L. Flowers ... [et al.] -- pt. III. Clock applications in space. Recent progress on the ACES mission (Invited) / L. Cacciapuoti and C. Salomon. The SAGAS mission (Invited) / P. Wolf. Small mercury microwave ion clock for navigation and radioScience (Invited) / J. D. Prestage ... [et al.]. Astro-comb: revolutionizing precision spectroscopy in astrophysics (Invited) / C. E. Kramer ... [et al.]. High frequency very long baseline interferometry: frequency standards and imaging an event horizon (Invited) / S. Doeleman. Optically-pumped space cesium clock for Galileo: results of the breadboard / R. Ruffieux ... [et al.] -- pt. IV. Optical clocks I: lattice clocks. Optical lattice clock: seven years of progress and next steps (Invited) / H. Katori, M. Takamoto and T. Akatsuka. The Yb optical lattice clock (Invited) / N. D. Demke ... [et al.]. Optical Lattice clock with Sr atoms (Invited) / P. G. Westergaard ... [et al.]. Development of an optical clock based on neutral strontium atoms held in a lattice trap / E. A. Curtis ... [et al.]. Decoherence and losses by collisions in a [symbol]Sr lattice clock / J. S. R. Vellore Winfred ... [et al.]. Lattice Yb optical clock and cryogenic Cs fountain at INRIM / F. Levi ... [et al.] -- pt. V. Optical clocks II: ion clocks. [Symbol]Yb+ single-ion optical frequency standards (Invited) / Chr. Tamm ... [et al.]. An optical clock based on a single trapped [symbol]Sr+ ion (Invited) / H. S. Margolis ... [et al.]. A trapped [symbol]Yb+ ion optical frequency standard based on the [symbol] transition (Invited) / P. Gill ... [et al.]. Overview of highly accurate RF and optical frequency standards at the National Research Council of Canada (Invited) / A. A. Madej ... [et al.] -- pt. VI. Optical frequency combs. Extreme ultraviolet frequency combs for spectroscopy (Invited) / A. Ozawa ... [et al.]. Development of an optical clockwork for the single trapped strontium ion standard at 445 THz / J. E. Bernard ... [et al.]. A phase-coherent link between the visible and infrared spectral ranges using a combination of CW OPO and femtosecond laser frequency comb / E. V. Kovalchuk and A. Peters. Improvements to the robustness of a TI: sapphire-based femtosecond comb at NPL / V. Tsatourian ... [et al.] -- pt. VII. Atomic microwave standards. NIST FI and F2 (Invited) / T. P. Heavner ... [et al.]. Atomic fountains for the USNO master clock (Invited) / C. Ekstrom ... [et al.]. The transportable cesium fountain clock NIM5: its construction and performance (Invited) / T. Li ... [et al.].Compensated multi-pole merc

Maleki, Lute

2009-04-01

440

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

441

Seed dormancy distribution: explanatory ecological factors  

PubMed Central

Background and Aims Knowledge of those traits that vary with latitude should be helpful in predicting how they may evolve locally under climate change. In the sea beet Beta vulgaris ssp. maritima, seed dormancy largely controls the timing of germination, is highly heritable and varies geographically; it is therefore thought to be selected by climate. The aim here was to characterize the variation in seed dormancy among sea beet populations across the French distribution area, as well as the ecological factors in situ that are correlated with and that could therefore select for seed dormancy. The relative importance of genetic inheritance vs. non-genetic variation is also evaluated. Methods The proportions of dormant seeds from 85 natural populations encompassing different climates over the whole French distribution area were measured under controlled conditions. Germination phenology was observed in a common garden experiment. Dormancy variation of seeds collected in situ was compared with that of seeds collected on plants grown in the greenhouse. Key Results The proportions of dormant seeds in the greenhouse were highly variable, covering almost the entire range from 0 to 1, and followed a geographical pattern from lower dormancy at high latitudes to high dormancy at low latitudes. The distribution of dormancy was positively correlated with yearly temperatures, especially summer temperatures. Minimum temperatures in winter did not significantly explain the trait variation. The genetic component of the total variation was significant and is probably completed by an important adjustment to the local conditions brought about by maternal adaptive phenotypic plasticity. Conclusions Dormancy in sea beet could be interpreted as a way to limit summer germination and spread germination over the first autumn and spring or following autumns. This highly heritable trait has the potential to evolve in the relatively near future because of climate change. PMID:22952378

Wagmann, Kristen; Hautekèete, Nina-Coralie; Piquot, Yves; Meunier, Cécile; Schmitt, S. Eric; Van Dijk, Henk

2012-01-01

442

The evolution of massive black hole seeds  

E-print Network

We investigate the evolution of high redshift seed black hole masses at late times and their observational signatures. The massive black hole seeds studied here form at extremely high redshifts from the direct collapse of pre-galactic gas discs. Populating dark matter halos with seeds formed in this way, we follow the mass assembly of these black holes to the present time using a Monte-Carlo merger tree. Using this machinery we predict the black hole mass function at high redshifts and at the present time; the integrated mass density of black holes and the luminosity function of accreting black holes as a function of redshift. These predictions are made for a set of three seed models with varying black hole formation efficiency. Given the accuracy of current observational constraints, all 3 models can be adequately fit. Discrimination between the models appears predominantly at the low mass end of the present day black hole mass function which is not observationally well constrained. However, all our models predict that low surface brightness, bulgeless galaxies with large discs are least likely to be sites for the formation of massive seed black holes at high redshifts. The efficiency of seed formation at high redshifts has a direct influence on the black hole occupation fraction in galaxies at z=0. This effect is more pronounced for low mass galaxies. This is the key discriminant between the models studied here and the Population III remnant seed model. We find that there exists a population of low mass galaxies that do not host nuclear black holes. Our prediction of the shape of the black hole mass - velocity dispersion relation at the low mass end is in agreement with the recent observational determination from the census of low mass galaxies in the Virgo cluster.

M. Volonteri; G. Lodato; P. Natarajan

2007-09-04

443

Monolithic THz Frequency Multipliers  

NASA Technical Reports Server (NTRS)

Frequency multipliers are required as local oscillator sources for frequencies up to 2.7 THz for FIRST and airborne applications. Multipliers at these frequencies have not previously been demonstrated, and the object of this work was to show whether such circuits are really practical. A practical circuit is one which not only performs as well as is required, but also can be replicated in a time that is feasible. As the frequency of circuits is increased, the difficulties in fabrication and assembly increase rapidly. Building all of the circuit on GaAs as a monolithic circuit is highly desirable to minimize the complexity of assembly, but at the highest frequencies, even a complete monolithic circuit is extremely small, and presents serious handling difficulty. This is compounded by the requirement for a very thin substrate. Assembly can become very difficult because of handling problems and critical placement. It is very desirable to make the chip big enough to that it can be seen without magnification, and strong enough that it may be picked up with tweezers. Machined blocks to house the chips present an additional challenge. Blocks with complex features are very expensive, and these also imply very critical assembly of the parts. It would be much better if the features in the block were as simple as possible and non-critical to the function of the chip. In particular, grounding and other electrical interfaces should be done in a manner that is highly reproducible.

Erickson, N. R.; Narayanan, G.; Grosslein, R. M.; Martin, S.; Mehdi, I.; Smith, P.; Coulomb, M.; DeMartinez, G.

2001-01-01

444

Seed maturity differentially mediates metabolic responses in black soybean.  

PubMed

The soybean seed is placed in the middle of the morphological and developmental alterations, such as changes in seed size, weight, and colour, and alteration of the composition and contents of metabolites during maturation. In this study, we used black soybean seeds to investigate the effect of maturity on metabolite levels at different maturity stages. Seeds were sorted into five maturity categories, from M1 to M5, based on seed size and external pigmentation. Maturity stages M1, M3, and M5 are equivalent to R6, R7, and R8 on the soybean reproductive growth stage scale, indicating full seed, beginning maturity, and full maturity, respectively. As seed maturation progressed, the seed size decreased and the water soluble extract changed, indicating that a change of seed pigmentation occurred. At the same time, numerous metabolites responded differentially to seed maturation. The partial least squares (PLS) scores plot indicated that the metabolic alteration during maturation was clearly visible. Furthermore, isoflavones were highly associated with seed maturity on the PLS loading plot while fatty acids, glucose, fructose, and sucrose were less linked with seed maturity, indicating that those metabolites responded less to seed maturation. Overall, the results indicate that each category of metabolites is mediated differentially during maturation in black soybean seeds. PMID:23870927

Lee, Jinwook; Hwang, Young-Sun; Chang, Woo-Suk; Moon, Jung-Kyeong; Choung, Myoung-Gun

2013-12-01

445

High frequency energy measurements  

SciTech Connect

High-frequency (> 100 MHz) energy measurements present special problems to the experimenter. Environment or available electronics often limit the applicability of a given detector type. The physical properties of many detectors are frequency dependent and in some cases, the physical effect employed can be frequency dependent. State-of-the-art measurements generally involve a detection scheme in association with high-speed electronics and a method of data recording. Events can be single or repetitive shot requiring real time, sampling, or digitizing data recording. Potential modification of the pulse by the detector and the associated electronics should not be overlooked. This presentation will review typical applications, methods of choosing a detector, and high-speed detectors. Special considerations and limitations of some applications and devices will be described.

Stotlar, S.C.

1981-01-01

446

Hg(+) Frequency Standards  

NASA Technical Reports Server (NTRS)

In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

2000-01-01

447

Frequency division multiplex technique  

NASA Technical Reports Server (NTRS)

A system for monitoring a plurality of condition responsive devices is described. It consists of a master control station and a remote station. The master control station is capable of transmitting command signals which includes a parity signal to a remote station which transmits the signals back to the command station so that such can be compared with the original signals in order to determine if there are any transmission errors. The system utilizes frequency sources which are 1.21 multiples of each other so that no linear combination of any harmonics will interfere with another frequency.

Brey, H. (inventor)

1973-01-01

448

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

449

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

450

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

451

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

452

Insights into the effects of long-term artificial selection on seed size in maize.  

PubMed

Grain produced from cereal crops is a primary source of human food and animal feed worldwide. To understand the genetic basis of seed-size variation, a grain yield component, we conducted a genome-wide scan to detect evidence of selection in the maize Krug Yellow Dent long-term divergent seed-size selection experiment. Previous studies have documented significant phenotypic divergence between the populations. Allele frequency estimates for ?3 million single nucleotide polymorphisms (SNPs) in the base population and selected populations were estimated from pooled whole-genome resequencing of 48 individuals per population. Using FST values across sliding windows, 94 divergent regions with a median of six genes per region were identified. Additionally, 2729 SNPs that reached fixation in both selected populations with opposing fixed alleles were identified, many of which clustered in two regions of the genome. Copy-number variation was highly prevalent between the selected populations, with 532 total regions identified on the basis of read-depth variation and comparative genome hybridization. Regions important for seed weight in natural variation were identified in the maize nested association mapping population. However, the number of regions that overlapped with the long-term selection experiment did not exceed that expected by chance, possibly indicating unique sources of variation between the two populations. The results of this study provide insights into the genetic elements underlying seed-size variation in maize and could also have applications for other cereal crops. PMID:25037958

Hirsch, Candice N; Flint-Garcia, Sherry A; Beissinger, Timothy M; Eichten, Steven R; Deshpande, Shweta; Barry, Kerrie; McMullen, Michael D; Holland, James B; Buckler, Edward S; Springer, Nathan; Buell, C Robin; de Leon, Natalia; Kaeppler, Shawn M

2014-09-01

453

Seed Dormancy in Red Rice 1  

PubMed Central

The weak acid character of many previously identified, but otherwise chemically dissimilar, dormancy-breaking compounds may contribute to their physiological activity. To test this idea, short chain monocarboxylic acids of one to six carbons, for which no previous reports of such activity exist, were incubated with dormant, dehulled red rice (Oryza sativa) seeds. Greater than 90% germination was observed after 24 hours of imbibition with 19 millimolar formic, 53 millimolar acetic, 20 millimolar propionic, 28 millimolar butyric, 20 millimolar valeric, or 16 millimolar caproic acid followed by 7 to 14 days incubation on water at 30°C. Dormancy-breaking activity was pH-dependent. Incubation medium pH values that favored formation of the protonated species resulted in the highest germination percentages. There was no promotive effect of medium pH itself in the range of 3 to 7. In contrast, germination of intact seeds was less than 40% in the presence of 55 millimolar monocarboxylic acids at pH 3, unless seeds were partially dry-afterripened. The pH-dependent activity of these acids was maintained during afterripening of intact seeds. The results are consistent with the idea that the dissociable proton of weak acids is responsible for their dormancy-breaking activity. Many other weak acids may break seed dormancy but have been over-looked due to the rigid pH dependence necessary for activity. PMID:16665509

Cohn, Marc Alan; Chiles, Lisa A.; Hughes, John A.; Boullion, Karen J.

1987-01-01

454

Rotating Phasors- Negative Frequencies  

NSDL National Science Digital Library

This interactive phasor page allows you to control the values of a rotating phasor and see a visualization of each change that is done. You can control: one, pos/neg, two, beats, delta, sawtooth, square, triangle, time, zoom, plus you can put into five different values: Frequency (rel, HZ, mHZ), Amplitude (raw, rel), and Phases (Deg, Rad, unitrad).

2011-05-25

455

HF (High Frequency) Communications Frequency-Management Procedure for Forecasting the Frequency of Optimum Transmission.  

National Technical Information Service (NTIS)

This report describes a procedure for forecasting the Frequency of Optimum Transmission (FOT) on a high-frequency communications path when the Maximum Observable Frequency (MOF) on another path and an historical record of the correlations of MOFs measured...

M. Daehler

1984-01-01

456

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. PMID:24904627

Nonogaki, Hiroyuki

2014-01-01

457

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

458

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

459

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

460

Physical and mechanical properties of hemp seed  

NASA Astrophysics Data System (ADS)

The current study was conducted to investigate the effect of moisture content on the post-harvest physical and mechanical properties of hemp seed in the range of 5.39 to 27.12% d.b. Results showed that the effect of moisture content on the most physical properties of the grain was significant (P<0.05). The results of mechanical tests demonstrated that the effect of loading rate on the mechanical properties of hemp seed was not significant. However, the moisture content effect on rupture force and energy was significant (P<0.01). The lowest value of rupture force was obtained at the highest loading rate (3mm min-1)and in the moisture content of 27.12% d.b. Moreover, the interaction effects of loading rate and moisture content on the rupture force and energy of hemp seed were significant (P<0.05).

Taheri-Garavand, A.; Nassiri, A.; Gharibzahedi, S.

2012-04-01

461

Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements  

NASA Technical Reports Server (NTRS)

Theoretical and experimental frequency narrowing studies of a Ti:sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported.

Bair, Clayton H.; Brockman, Philip; Hess, Robert V.; Modlin, Edward A.

1988-01-01

462

Synchrony between fruit maturation and effective dispersers' foraging activity increases seed protection against seed predators  

PubMed Central

The evolution of pollination and seed dispersal mutualisms is conditioned by the spatial and temporal co-occurrence of animals and plants. In the present study we explore the timing of seed release of a myrmecochorous plant (Helleborus foetidus) and ant activity in two populations in southern Spain during 2 consecutive years. The results indicate that fruit dehiscence and seed shedding occur mostly in the morning and correspond to the period of maximum foraging activity of the most effective ant dispersers. By contrast, ant species that do not transport seeds and/or that do not abound near the plants are active either before or after H. foetidus diaspores are released. Experimental analysis of diet preference for three kinds of food shows that effective ant dispersers are mostly scavengers that readily feed on insect corpses and sugars. Artificial seed depots suggest that seeds deposited on the ground out of the natural daily time window of diaspore releasing are not removed by ants and suffer strong predation by nocturnal rodents Apodemus sylvaticus. Nevertheless, important inter-annual variations in rodent populations cast doubts on their real importance as selection agents. We argue that traits allowing synchrony between seed presentation and effective partners may constitute a crucial pre-adaptation for the evolution of plant–animal mutualisms involving numerous animal partners. PMID:17698486

Boulay, Raphael; Carro, Francisco; Soriguer, Ramon C; Cerda, Xim

2007-01-01

463

Low frequency phase signal measurement with high frequency squeezing  

E-print Network

We calculate the utility of high-frequency squeezed-state enhanced two-frequency interferometry for low-frequency phase measurement. To use the high-frequency sidebands of the squeezed light, a two-frequency intense laser is used in the interferometry instead of a single-frequency laser as usual. We find that the readout signal can be contaminated by the high-frequency phase vibration, but this is easy to check and avoid. A proof-of-principle experiment is in the reach of modern quantum optics technology.

Zehui Zhai; Jiangrui Gao

2011-01-14

464

Dose profile establishment of new I-125 brachytherapy seed by radiochromic film  

E-print Network

this new brachytherapy seed to be similar to the commercially available model 6711 seed because of similar source geometry. Exposures with the seed embedded in a paraffin medium produced different profiles from when the seed was embedded in Plexiglas...

Lee, Sung-Woo

2012-06-07

465

7 CFR 361.7 - Special provisions for Canadian-origin seed and screenings.  

Code of Federal Regulations, 2012 CFR

...a private seed laboratory accredited by the Canadian Food Inspection Agency. S