154 research outputs found
New insights on arabidopsis thaliana root adaption to ammonium nutrition by the use of a quantitative proteomic approach
Nitrogen is an essential element for plant nutrition. Nitrate and ammonium are the two
major inorganic nitrogen forms available for plant growth. Plant preference for one or the other
form depends on the interplay between plant genetic background and environmental variables.
Ammonium-based fertilization has been shown less environmentally harmful compared to nitrate
fertilization, because of reducing, among others, nitrate leaching and nitrous oxide emissions.
However, ammonium nutrition may become a stressful situation for a wide range of plant species
when the ion is present at high concentrations. Although studied for long time, there is still an
important lack of knowledge to explain plant tolerance or sensitivity towards ammonium nutrition.
In this context, we performed a comparative proteomic study in roots of Arabidopsis thaliana plants
grown under exclusive ammonium or nitrate supply. We identified and quantified 68 proteins with
differential abundance between both conditions. These proteins revealed new potential important
players on root response to ammonium nutrition, such as H+
-consuming metabolic pathways
to regulate pH homeostasis and specific secondary metabolic pathways like brassinosteroid and
glucosinolate biosynthetic pathways
The NEMP family supports metazoan fertility and nuclear envelope stiffness.
Human genome-wide association studies have linked single-nucleotide polymorphisms (SNPs) in NEMP1 (nuclear envelope membrane protein 1) with early menopause; however, it is unclear whether NEMP1 has any role in fertility. We show that whole-animal loss of NEMP1 homologs in Drosophila, Caenorhabditis elegans, zebrafish, and mice leads to sterility or early loss of fertility. Loss of Nemp leads to nuclear shaping defects, most prominently in the germ line. Biochemical, biophysical, and genetic studies reveal that NEMP proteins support the mechanical stiffness of the germline nuclear envelope via formation of a NEMP-EMERIN complex. These data indicate that the germline nuclear envelope has specialized mechanical properties and that NEMP proteins play essential and conserved roles in fertility
Statefinder diagnostic and analysis for interacting polytropic gas dark energy model
The interacting polytropic gas dark energy model is investigated from the
viewpoint of statefinder diagnostic tool and analysis. The
dependency of the statefinder parameters on the parameter of the model as well
as the interaction parameter between dark matter and dark energy is calculated.
We show that different values of the parameters of model and different values
of interaction parameter result different evolutionary trajectories in
and planes. The polytropic gas model of dark energy mimics the
standard CDM model at the early time.Comment: 17 pages, 4 figures, ijtp accepte
Evaluation of time domain electromagnetic fields radiated by constant velocity moving particles traveling along an arbitrarily shaped cross-section waveguide using frequency domain Green's functions
A technique for the accurate computation of the time domain electromagnetic fields radiated by a charged distribution traveling along an arbitrarily shaped waveguide region is presented. Based on the transformation (by means of the standard Fourier analysis) of the time-varying current density of the analyzed problem to the frequency domain, the resulting equivalent current is further convolved with the dyadic electric and magnetic Green's functions. Moreover, we show that only the evaluation of the transverse magnetic modes of the structure is required for the calculation of fields radiated by particles traveling in the axial direction. Finally, frequency domain electric and magnetic fields are transformed back to the time domain, just obtaining the total fields radiated by the charged distribution. Furthermore, we present a method for the computation of the wakefields of arbitrary cross-section uniform waveguides from the resulting field expressions. Several examples of charged particles moving in the axial direction of such waveguides are included.The authors would like to thank ESA/ESTEC for having cofunded this research activity through the Network Partnering Initiative program and through the project "Multipactor Analysis in Planar Transmission Lines" (contract 20841/08/NL/GLC). We also are grateful to the Spanish government and the local Council of Murcia for their support through the projects CICYT Ref. TEC2010-21520-C04-04 and SENECA Ref. 08833/PI/08, respectively.Jimenez Nogales, M.; Marini, S.; Gimeno Martinez, B.; Alvarez Melcon, A.; Quesada Pereira, FD.; Boria Esbert, VE.; Soto Pacheco, P.... (2012). Evaluation of time domain electromagnetic fields radiated by constant velocity moving particles traveling along an arbitrarily shaped cross-section waveguide using frequency domain Green's functions. Radio Science. 47(5):1-14. https://doi.org/10.1029/2012RS005008S114475Alvarez-Melcon, A., & Mosig, J. R. (2000). Two techniques for the efficient numerical calculation of the Green’s functions for planar shielded circuits and antennas. IEEE Transactions on Microwave Theory and Techniques, 48(9), 1492-1504. doi:10.1109/22.869000Bane, K. L. F., Wilson, P. B., & Weiland, T. (1985). Wake fields and wake field acceleration. AIP Conference Proceedings. doi:10.1063/1.35182Bozzi, M., Perregrini, L., Alvarez Melcon, A., Guglielmi, M., & Conciauro, G. (2001). MoM/BI-RME analysis of boxed MMICs with arbitrarily shaped metallizations. IEEE Transactions on Microwave Theory and Techniques, 49(12), 2227-2234. doi:10.1109/22.971604Burov, A., & Danilov, V. (1999). Suppression of Transverse Bunch Instabilities by Asymmetries in the Chamber Geometry. Physical Review Letters, 82(11), 2286-2289. doi:10.1103/physrevlett.82.2286Cogollos, S., Marini, S., Boria, V. E., Soto, P., Vidal, A., Esteban, H., … Gimeno, B. (2003). Efficient modal analysis of arbitrarily shaped waveguides composed of linear, circular, and elliptical arcs using the BI-RME method. IEEE Transactions on Microwave Theory and Techniques, 51(12), 2378-2390. doi:10.1109/tmtt.2003.819776Conciauro, G., Bressan, M., & Zuffada, C. (1984). Waveguide Modes Via an Integral Equation Leading to a Linear Matrix Eigenvalue Problem. IEEE Transactions on Microwave Theory and Techniques, 32(11), 1495-1504. doi:10.1109/tmtt.1984.1132880Deshpande , M. D. 1997 Analysis of discontinuities in a rectangular waveguide using dyadic Green's function approach in conjuntion with Method of Moments Langley Res. Cent., NASA Hampton, Va.Felsen, L. B., & Marcuvitz, N. (1994). Radiation and Scattering of Waves. doi:10.1109/9780470546307Figueroa, H., Gai, W., Konecny, R., Norem, J., Ruggiero, A., Schoessow, P., & Simpson, J. (1988). Direct Measurement of Beam-Induced Fields in Accelerating Structures. Physical Review Letters, 60(21), 2144-2147. doi:10.1103/physrevlett.60.2144Gai, W., Kanareykin, A. D., Kustov, A. L., & Simpson, J. (1997). Numerical simulations of intense charged-particle beam propagation in a dielectric wake-field accelerator. Physical Review E, 55(3), 3481-3488. doi:10.1103/physreve.55.3481Gluckstern, R. L., van Zeijts, J., & Zotter, B. (1993). Coupling impedance of beam pipes of general cross section. Physical Review E, 47(1), 656-663. doi:10.1103/physreve.47.656Hanson, G. W., & Yakovlev, A. B. (2002). Operator Theory for Electromagnetics. doi:10.1007/978-1-4757-3679-3Hess, M., Park, C. S., & Bolton, D. (2007). Green’s function based space-charge field solver for electron source simulations. Physical Review Special Topics - Accelerators and Beams, 10(5). doi:10.1103/physrevstab.10.054201Iriso-Ariz, U., Caspers, F., & Mostacci, A. (s. f.). Evaluation of the horizontal to vertical transverse impedance ratio for LHC beam screen using a 2D electrostatic code. Proceedings of the 2003 Bipolar/BiCMOS Circuits and Technology Meeting (IEEE Cat. No.03CH37440). doi:10.1109/pac.2003.1289954Jing, C., Liu, W., Xiao, L., Gai, W., Schoessow, P., & Wong, T. (2003). Dipole-mode wakefields in dielectric-loaded rectangular waveguide accelerating structures. Physical Review E, 68(1). doi:10.1103/physreve.68.016502Kim, S. H., Chen, K. W., & Yang, J. S. (1990). Modal analysis of wake fields and its application to elliptical pill‐box cavity with finite aperture. Journal of Applied Physics, 68(10), 4942-4951. doi:10.1063/1.347079Lutman, A., Vescovo, R., & Craievich, P. (2008). Electromagnetic field and short-range wake function in a beam pipe of elliptical cross section. Physical Review Special Topics - Accelerators and Beams, 11(7). doi:10.1103/physrevstab.11.074401Ng, K.-Y. (1990). Wake fields in a dielectric-lined waveguide. Physical Review D, 42(5), 1819-1828. doi:10.1103/physrevd.42.1819Palumbo, L., Vaccaro, V. G., & Wustefeld, G. (1984). Coupling Impedance in a Circular Particle Accelerator, a Particular Case: Circular Beam, Elliptic Chamber. IEEE Transactions on Nuclear Science, 31(4), 1011-1020. doi:10.1109/tns.1984.4333427Panofsky, W. K. H., & Wenzel, W. A. (1956). Some Considerations Concerning the Transverse Deflection of Charged Particles in Radio‐Frequency Fields. Review of Scientific Instruments, 27(11), 967-967. doi:10.1063/1.1715427Rahmat-Samii, Y. (1975). On the Question of Computation of the Dyadic Green’s Function at the Source Region in Waveguides and Cavities (Short Papers). IEEE Transactions on Microwave Theory and Techniques, 23(9), 762-765. doi:10.1109/tmtt.1975.1128671Rosing, M., & Gai, W. (1990). Longitudinal- and transverse-wake-field effects in dielectric structures. Physical Review D, 42(5), 1829-1834. doi:10.1103/physrevd.42.1829Rumolo, G., Ruggiero, F., & Zimmermann, F. (2001). Simulation of the electron-cloud build up and its consequences on heat load, beam stability, and diagnostics. Physical Review Special Topics - Accelerators and Beams, 4(1). doi:10.1103/physrevstab.4.012801Salah, W. (2004). Analytical and numerical investigations of the evolution of wake fields of accelerated electron beams encountering cavity discontinuities in laser-driven RF-free electron laser photoinjector. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 533(3), 248-257. doi:10.1016/j.nima.2004.05.129Salah, W., & Dolique, J.-M. (1999). Wake field of electron beam accelerated in a RF-gun of free electron laser «ELSA». Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 431(1-2), 27-37. doi:10.1016/s0168-9002(99)00255-7Stupakov, G., Bane, K. L. F., & Zagorodnov, I. (2007). Optical approximation in the theory of geometric impedance. Physical Review Special Topics - Accelerators and Beams, 10(5). doi:10.1103/physrevstab.10.054401Wang, J. J. H. (1978). Analysis of a Three-Dimensional Arbitrarily Shaped Dielectric or Biological Body Inside a Rectangular Waveguide. IEEE Transactions on Microwave Theory and Techniques, 26(7), 457-462. doi:10.1109/tmtt.1978.1129416Wangler, T. P. (2008). RF Linear Accelerators. doi:10.1002/9783527623426Xiao, L., Gai, W., & Sun, X. (2001). Field analysis of a dielectric-loaded rectangular waveguide accelerating structure. Physical Review E, 65(1). doi:10.1103/physreve.65.016505Zagorodnov, I. (2006). Indirect methods for wake potential integration. Physical Review Special Topics - Accelerators and Beams, 9(10). doi:10.1103/physrevstab.9.102002Zimmermann , F. 1997 A simulation study of electron-cloud instability and beam-induced multipacting in the LHC Eur. Org. for Nucl. Res. Geneva, SwitzerlandZotter, B. W., & Kheifets, S. (1998). Impedances and Wakes in High Energy Particle Accelerators. doi:10.1142/306
Stable Isotope Biogeochemistry of Seabird Guano Fertilization: Results from Growth Chamber Studies with Maize (Zea Mays)
Stable isotope analysis is being utilized with increasing regularity to examine a wide range of issues (diet, habitat use, migration) in ecology, geology, archaeology, and related disciplines. A crucial component to these studies is a thorough understanding of the range and causes of baseline isotopic variation, which is relatively poorly understood for nitrogen (δ(15)N). Animal excrement is known to impact plant δ(15)N values, but the effects of seabird guano have not been systematically studied from an agricultural or horticultural standpoint.This paper presents isotopic (δ(13)C and δ(15)N) and vital data for maize (Zea mays) fertilized with Peruvian seabird guano under controlled conditions. The level of (15)N enrichment in fertilized plants is very large, with δ(15)N values ranging between 25.5 and 44.7‰ depending on the tissue and amount of fertilizer applied; comparatively, control plant δ(15)N values ranged between -0.3 and 5.7‰. Intraplant and temporal variability in δ(15)N values were large, particularly for the guano-fertilized plants, which can be attributed to changes in the availability of guano-derived N over time, and the reliance of stored vs. absorbed N. Plant δ(13)C values were not significantly impacted by guano fertilization. High concentrations of seabird guano inhibited maize germination and maize growth. Moreover, high levels of seabird guano greatly impacted the N metabolism of the plants, resulting in significantly higher tissue N content, particularly in the stalk.The results presented in this study demonstrate the very large impact of seabird guano on maize δ(15)N values. The use of seabird guano as a fertilizer can thus be traced using stable isotope analysis in food chemistry applications (certification of organic inputs). Furthermore, the fertilization of maize with seabird guano creates an isotopic signature very similar to a high-trophic level marine resource, which must be considered when interpreting isotopic data from archaeological material
- …