bluuebunny/crossref_metadata_2025 huggingface dataset:
Soliton cellular automaton associated with $D_n^{(1)}$Dn(1)-crystal B2,s
Authors: Misra Kailash C. , Wilson Evan A.
Published: April 2013

A solvable vertex model in ferromagnetic regime gives rise to a soliton cellular automaton which is a discrete dynamical system in which site variables take on values in a finite set. We study the scattering of a class of soliton cellular automata associated with the \documentclass[12pt]{minimal}\begin{document}$U_q(D_n^{(1)})$\end{document}Uq(Dn(1))-perfect crystal B2, s. We calculate the combinatorial R matrix for all elements of B2, s ⊗ B2, 1. In particular, we show that the scattering rule for our soliton cellular automaton can be identified with the combinatorial R matrix for \documentclass[12pt]{minimal}\begin{document}$U_q(A_1^{(1)}) \oplus U_q(D_{n-2}^{(1)})$\end{document}Uq(A1(1))⊕Uq(Dn−2(1))-crystals.
Ferromagnetism in Mn half-doped LaCrO3 perovskite
Authors: Barrozo Petrucio , Albino Aguiar J.
Published: April 2013

In this work, we present results on the structural, electrical, and magnetic properties of pure and half-doped LaCrO3 compounds. It is observed that including Mn the lattice structure changes from orthorhombic to rhombohedral. The electrical transport in LaCrO3 can be described by a band gap model, whereas in La2CrMnO6, a charge localization occurs and the electrical transport is described by a variable range hopping model. The magnetic measurements show that LaCrO3 is a G-type antiferromagnetic with a Neel temperature at 290 K, and the Mn doping favors the ferromagnetic order and reduces the transition temperature.
Virasoro type algebraic structure hidden in the constrained discrete Kadomtsev-Petviashvili hierarchy
Authors: Li Maohua , Li Chuanzhong , Tian Keilei , He Jingsong , Cheng Yi
Published: April 2013

In this paper, we construct the additional symmetries of one-component constrained discrete Kadomtsev-Petviashvili hierarchy, and then prove that the algebraic structure of the symmetry flows is the positive half of Virasoro algebra.
Bifurcations in a low-order nonlinear model of tropical Pacific sea surface temperatures derived from observational data
Authors: Hong Mei , Zhang Ren , Wang Hui-Zan , Ge Jing-jing , Pan Ao-Da
Published: April 2013

Aiming at tackling the difficulty in exactly constituting the sea surface temperature (SST) dynamical model, the paper introduces the dynamical system reconstruction idea and establishes the nonlinear dynamical model of SST field based on 1963-2010 monthly average Hadley SST data. Time coefficients series after empirical orthogonal functions decomposition are taken as the dynamical model variables and Genetic Algorithms is used to optimize and retrieve the model parameters. The stability of the equilibrium in the reconstructed model is analyzed and dynamical actions such as bifurcation and mutation are discussed. Also the activity configuration and aberrance mechanism of the SST field are developed upon the actual activity characteristics of the SST field in the Tropical Pacific Ocean in that year. Results reveal that the bifurcation action of the SST field system from one stable high-value equilibrium to another stable low-value equilibrium accords with the La Niña process while the mutation action of the SST field system from two stable equilibriums to another stable equilibrium accords with the El Niño process.
Characterization of multiscroll attractors using Lyapunov exponents and Lagrangian coherent structures
Authors: Fazanaro Filipe I. , Soriano Diogo C. , Suyama Ricardo , Attux Romis , Madrid Marconi K. , Raimundo de Oliveira José
Published: April 2013

The present work aims to apply a recently proposed method for estimating Lyapunov exponents to characterize—with the aid of the metric entropy and the fractal dimension—the degree of information and the topological structure associated with multiscroll attractors. In particular, the employed methodology offers the possibility of obtaining the whole Lyapunov spectrum directly from the state equations without employing any linearization procedure or time series-based analysis. As a main result, the predictability and the complexity associated with the phase trajectory were quantified as the number of scrolls are progressively increased for a particular piecewise linear model. In general, it is shown here that the trajectory tends to increase its complexity and unpredictability following an exponential behaviour with the addition of scrolls towards to an upper bound limit, except for some degenerated situations where a non-uniform grid of scrolls is attained. Moreover, the approach employed here also provides an easy way for estimating the finite time Lyapunov exponents of the dynamics and, consequently, the Lagrangian coherent structures for the vector field. These structures are particularly important to understand the stretching/folding behaviour underlying the chaotic multiscroll structure and can provide a better insight of phase space partition and exploration as new scrolls are progressively added to the attractor.
Solar light trapping in slanted conical-pore photonic crystals: Beyond statistical ray trapping
Authors: Eyderman Sergey , John Sajeev , Deinega Alexei
Published: April 2013

We demonstrate that with only 1 μm, equivalent bulk thickness, of crystalline silicon, sculpted into the form of a slanted conical-pore photonic crystal and placed on a silver back-reflector, it is possible to attain a maximum achievable photocurrent density (MAPD) of 35.5 mA/cm2 from impinging sunlight. This corresponds to absorbing roughly 85% of all available sunlight in the wavelength range of 300–1100 nm and exceeds the limits suggested by previous “statistical ray trapping” arguments. Given the AM 1.5 solar spectrum and the intrinsic absorption characteristics of silicon, the optimum carrier generation occurs for a photonic crystal square lattice constant of 850 nm and slightly overlapping inverted cones with upper (base) radius of 500 nm. This provides a graded refractive index profile with good anti-reflection behavior. Light trapping is enhanced by tilting each inverted cone such that one side of each cone is tangent to the plane defining the side of the elementary cell. When the solar cell is packaged with silica (each pore filled with SiO2), the MAPD in the wavelength range of 400–1100 nm becomes 32.6 mA/cm2 still higher than the Lambertian 4n2 benchmark of 31.2 mA/cm2. In the near infrared regime from 800 to 1100 nm, our structure traps and absorbs light within slow group velocity modes, which propagate nearly parallel to the solar cell interface and exhibit localized high intensity vortex-like flow in the Poynting vector-field. In this near infrared range, our partial MAPD is 10.9 mA/cm2 compared to a partial MAPD of 7 mA/cm2 based on “4n2 statistical ray trapping.” These results suggest silicon solar cell efficiencies exceeding 20% with just 1 μm of silicon.
Strain modified/enhanced ferromagnetism in Mn3Ge2 thin films on GaAs(001) and GaSb(001)
Authors: Duc Dung Dang , Feng Wuwei , Van Thiet Duong , Park In-Sung , Bo Lee Sung , Cho Sunglae
Published: April 2013

Ferromagnetic Mn3Ge2 thin films were successfully grown on GaAs(001) and GaSb(001) substrates using molecular beam epitaxy. The results of our work revealed that the substrate facilitates to modify magnetic and electrical properties of Mn3Ge2 films due to tensile/compressive strain effect between films and substrates. The characteristic spin-flopping transition at around 150 K for the bulk Mn3Ge2 disappeared completely for both samples. The antiferromagnetism below 150 K changed to ferromagnetism and retained above room temperature. The saturation magnetization was found to be 0.23 and 1.32 μB/Mn atom at 10 K for the samples grown on GaSb(001) and GaAs(001), respectively.
Direct piezoelectric responses of soft composite fiber mats
Authors: Varga M. , Morvan J. , Diorio N. , Buyuktanir E. , Harden J. , West J. L. , Jákli A.
Published: April 2013

Recently soft fiber mats electrospun from solutions of Barium Titanate (BT) ferroelectric ceramics particles and polylactic acid (PLA) were found to have large (d33 ∼ 1 nm/V) converse piezoelectric signals offering a myriad of applications ranging from active implants to smart textiles. Here, we report direct piezoelectric measurements (electric signals due to mechanical stress) of the BT/PLA composite fiber mats at several BT concentrations. A homemade testing apparatus provided AC stresses in the 50 Hz-1.5 kHz-frequency range. The piezoelectric constant d33 ∼ 0.5 nC/N and the compression modulus Y ∼ 104–105 Pa found are in agreement with the prior converse piezoelectric and compressibility measurements. Importantly, the direct piezoelectric signal is large enough to power a small LCD by simple finger tapping of a 0.15 mm thick 2-cm2 area mat. We propose using these mats in active Braille cells and in liquid crystal writing tablets.
d-orbital ordering of oxygen-deficient amorphous and anatase TiO2−x channels for high mobility thin film transistors
Authors: Choi Kwang-Hyuk , Chung Kwun-Bum , Kim Han-Ki
Published: April 2013

Semiconducting behavior in oxygen-deficient amorphous and anatase TiO2−x films prepared by direct current magnetron sputtering was investigated for high mobility oxide thin film transistors (OxTFTs). Rapid thermal annealing (RTA) was found to induce transition from an amorphous to anatase phase in oxygen-deficient TiO2−x channels and was significantly influenced by DC power during sputtering. Compared to the low field effect mobility (μFE: 0.57 cm2/V s) of OxTFTs with d-orbital ordered amorphous TiO2−x channels, OxTFTs with anatase TiO2−x channels exhibited a higher mobility (μFE: 1.02 cm2/V s) due to an increased amount of free carriers and effective d-orbital ordering. In addition, the oxygen ambient annealing time during the RTA process had a critical effect on Von shift and shallow/deep trap states of anatase TiO2−x-based TFTs.
Mesoscopic photonic structures in glasses by femtosecond-laser fashioned confinement of semiconductor quantum dots
Authors: Mardilovich Pavel , Yang Lihmei , Huang Huan , Krol Denise M. , Risbud Subhash H.
Published: April 2013

Optically tunable mesoscale structures offer unparalleled potential for photonic device applications. Here, we report the creation of composite photonic structures consisting of CdSxSe1−x quantum dots (QDs) customized within lines, first written in a glass by femtosecond laser pulses. CdSxSe1−x-doped borosilicate glasses were pulsed with a fs-laser using a 473 kHz repetition rate to create chemically distinct microscopic regions. Upon further heat treatment, these regions served as “micro-crucibles” within which quantum dots were precipitated exclusively. These results open prospects of developing other semiconductor doped glasses for versatile photonic structures useful over broader optical wavelengths.
Shallow acceptor complexes in p-type ZnO
Authors: Reynolds J. G. , Reynolds C. L. , Mohanta A. , Muth J. F. , Rowe J. E. , Everitt H. O. , Aspnes D. E.
Published: April 2013

We show that N-doped ZnO films grown on sapphire can exhibit significant (∼1018 cm−3) room-temperature p-type behavior when sufficient nitrogen (N) is incorporated and the material is annealed appropriately. Substitutional N on the oxygen (O) sublattice is a deep acceptor; however, shallow acceptor complexes involve N, H, and zinc vacancies (VZn). Combining secondary ion mass spectrometry, Raman-scattering, photoluminescence, and Hall-effect data, we establish the evolution of N from its initial incorporation on a Zn site to a final shallow acceptor complex VZn_NO_H+ with an ionization energy of ca. 130 meV. This complex is responsible for the observed p-type behavior.
Reduction of 1/f noise in graphene after electron-beam irradiation
Authors: Zahid Hossain Md. , Rumyantsev Sergey , Shur Michael S. , Balandin Alexander A.
Published: April 2013

We investigated experimentally the effect of the electron-beam irradiation on the level of the low-frequency 1/f noise in graphene devices. It was found that 1/f noise in graphene reduces with increasing concentration of defects induced by irradiation. The increased amount of structural disorder in graphene under irradiation was verified with micro-Raman spectroscopy. The bombardment of graphene devices with 20-keV electrons reduced the noise spectral density, SI/I2 (I is the source-drain current) by an order-of magnitude at the radiation dose of 104 μC/cm2. We analyzed the observed noise reduction in the limiting cases of the mobility and carrier number fluctuation mechanisms. The obtained results are important for the proposed graphene applications in analog, mixed-signal, and radio-frequency systems, integrated circuits and sensors.
High quality interfaces of InAs-on-insulator field-effect transistors with ZrO2 gate dielectrics
Authors: Takei Kuniharu , Kapadia Rehan , Fang Hui , Plis E. , Krishna Sanjay , Javey Ali
Published: April 2013

Interface quality of InAs-on-insulator (XOI) field-effect transistors (FETs) with a ZrO2 gate dielectric is examined as a function of various chemical treatments. With a forming gas anneal, InAs XOI FETs exhibit a low subthreshold swing of ∼72 mV/dec with an interface trap density of ∼1.5 × 1012 states/cm2 eV—both of which are comparable to the best reported epitaxially grown III-V devices on III-V substrates. Importantly, the results indicate that the surface properties of InAs are preserved during the layer transfer process, thereby, enabling the realization of high performance III-V FETs on Si substrates using the XOI configuration.
Electrostrictive effect in Pb(Mg1/3Nb2/3)O3-xPbTiO3 crystals
Authors: Li Fei , Jin Li , Xu Zhuo , Wang Dawei , Zhang Shujun
Published: April 2013

The electrostrictive effect was investigated in Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) relaxor ferroelectric crystal, a representative high performance piezoelectric material, with respect to orientation, temperature, and composition. The electrostrictive coefficients Q11C, Q12C, and Q44C of PMN-xPT (x = 0.25−0.37) crystals were found to be on the order of 0.055, −0.024, and 0.020 m4/C2, respectively. The maximum and minimum Q33* were found to be along 〈100〉 and 〈111〉 directions, being about 0.055 and 0.014 m4/C2, respectively, showing a strong anisotropic behavior, which is inherently associated with the oxygen-octahedra structure. In contrast to piezoelectric and dielectric responses, the electrostrictive coefficients Q are found to be insensitive to the ferroelectric phase transition, no matter it is induced by the temperature or composition.
Single domain Bi2Se3 films grown on InP(111)A by molecular-beam epitaxy
Authors: Guo X. , Xu Z. J. , Liu H. C. , Zhao B. , Dai X. Q. , He H. T. , Wang J. N. , Liu H. J. , Ho W. K. , Xie M. H.
Published: April 2013

We report the growth of single-domain epitaxial Bi2Se3 films on InP(111)A substrate by molecular-beam epitaxy. Nucleation of Bi2Se3 proceeds at steps, so the lattices of the substrate play the guiding role for a unidirectional crystalline film in the step-flow growth mode. There exists a strong chemical interaction between atoms at the heterointerface, so the growth does not follow the van der Waals epitaxy process. A mounded morphology of thick Bi2Se3 epilayers suggests a growth kinetics dictated by the Ehrlich-Schwoebel barrier. The Schubnikov de Haas oscillations observed in magnetoresistance measurements are attributed to Landau quantization of the bulk states of electrons.
Transient and steady-state dark current mechanisms in amorphous selenium avalanche radiation detectors
Authors: Kabir M. Z. , Imam Safayat-Al
Published: April 2013

A theoretical model for describing bias-dependent transient and steady-state behaviors of dark current in amorphous selenium (a-Se) avalanche detector structures has been developed. The analytical model considers bulk thermal generation current from mid-gap sates, transient carrier depletion, and carrier injection from the electrodes incorporating avalanche multiplication. The proposed physics-based dark current model is compared with the published experimental results on three potential a-Se avalanche detector structures. The steady-state dark current is the minimum for the structures that have effective blocking layers for both holes and electrons. The transient decay time to reach a plateau decreases considerably with increasing electric field.
Phase behaviors of agarose gel
Authors: Morita Takaharu , Narita Takayuki , Mukai Sada-atsu , Yanagisawa Miho , Tokita Masayuki
Published: April 2013

We present evidence for the existence of phase separation in the gel state of agarose having the mixture of water and methanol as the gelsolvent. Firstly, the sol-geltransition line and the cloud point line are determined independently as a function of the concentration of agarose as well as the concentration of methanol in the mixed solvent by the quasi-equilibrium cooling of the solutions. Then the spinodal line is determined by quenching the solutions below the sol-geltransition line. We find that the spinodal line appears below the cloud point line and both lines are entirely buried below the sol-geltransition line in the aqueous agarose system. The concentration fluctuations are, therefore, frozen into the polymer network of agarose gel that promotes the opacity of the resultant gel. The structure of agarose gel is observed by the confocal laser scanning microscope (CLSM)imaging technique that reveals that the density fluctuations are grown up to micrometer scale in space. The phase separationboundary is found to shift to the higher temperature region than the sol-geltransition line when the concentration of methanol in the mixed solvent is increased. The results indicate that the position of the phase separation boundary in relative to the sol-geltransition line varies with the quality of solvent.These results are in agreement with the theory of the sol-geltransition in which both the divergence of the connectivity and the thermodynamic instability are taken into account.
Supersymmetric Ito equation: Bosonization and exact solutions
Authors: Ren Bo , Lin Ji , Yu Jun
Published: April 2013

Based on the bosonization approach, the \documentclass[12pt]{minimal}\begin{document}${\cal N} =1$\end{document}N=1 supersymmetric Ito (sIto) system is changed to a system of coupled bosonic equations. The approach can effectively avoid difficulties caused by intractable fermionic fields which are anticommuting. By solving the coupled bosonic equations, the traveling wave solutions of the sIto system are obtained with the mapping and deformation method. Some novel types of exact solutions for the supersymmetric system are constructed with the solutions and symmetries of the usual Ito equation. In the meanwhile, the similarity reduction solutions of the model are also studied with the Lie point symmetry theory.
Poly (vinylidene fluoride-trifluoroethylene)/barium titanate nanocomposite for ferroelectric nonvolatile memory devices
Authors: Valiyaneerilakkal Uvais , Varghese Soney
Published: April 2013

The effect of barium titanate (BaTiO3) nanoparticles (particle size <100nm) on the ferroelectric properties of poly (vinylidenefluoride-trifluoroethylene) P(VDF-TrFE) copolymer has been studied. Different concentrations of nanoparticles were added to P(VDF-TrFE) using probe sonication, and uniform thin films were made. Polarisation - Electric field (P-E) hysteresis analysis shows an increase in remnant polarization (Pr) and decrease in coercive voltage (Vc). Piezo-response force microscopy analysis shows the switching capability of the polymercomposite. The topography and surface roughness was studied using atomic force microscopy. It has been observed that this nanocomposite can be used for the fabrication of non-volatile ferroelectric memorydevices.
Genetics of early conception and its relationship to growth traits in red deer (Cervus elaphus)
Authors: Archer J. A. , Asher G. W. , Fisher P. J. , Ward J. F. , Scott I. C. , Bixley M. J. , Hickey S. M. , Morris C. A.
Published: April 2013

The genetics of early conception success and live-animal growth were studied in five herds of red deer in New Zealand. Conception date (CD) was used as the criterion of success in seasonally mated hinds, with 2493 mating records available. Liveweights analysed were weaning weight, yearling weight, 15-month weight and mature weight (hinds only). CD and liveweights were analysed using restricted maximum likelihood procedures with an animal model, including all available pedigree records. Under the management conditions applied, CD had a phenotypic standard deviation of 7.9 days, a repeatability across years of 0.29 ± 0.03 and a direct (univariate) heritability of 0.20 ± 0.06. Regression procedures using DNA markers to adjust the data for genetic differences resulting from an animal’s ancestral region of origin (mainly western vs eastern European) had little effect on the parameter estimates above. Direct heritability estimates for the four weight traits were 0.38 ± 0.03, 0.49 ± 0.02, 0.48 ± 0.04 and 0.46 ± 0.04, respectively, while the genetic correlations between CD and these traits (e.g. using 1763 paired records of CD with yearling weight) were –0.24 ± 0.11, –0.24 ± 0.09, –0.16 ± 0.10 and –0.04 ± 0.09, respectively. Selection for earlier CD would be successful and compatible with selection for higher juvenile weights.
Protection against malaria after immunization by chloroquine prophylaxis and sporozoites is mediated by preerythrocytic immunity
Authors: Bijker Else M. , Bastiaens Guido J. H. , Teirlinck Anne C. , van Gemert Geert-Jan , Graumans Wouter , van de Vegte-Bolmer Marga , Siebelink-Stoter Rianne , Arens Theo , Teelen Karina , Nahrendorf Wiebke , Remarque Edmond J. , Roeffen Will , Jansens Annemieke , Zimmerman Dunja , Vos Martijn , van Schaijk Ben C. L. , Wiersma Jorien , van der Ven André J. A. M. , de Mast Quirijn , van Lieshout Lisette , Verweij Jaco J. , Hermsen Cornelus C. , Scholzen Anja , Sauerwein Robert W.
Published: April 2013

Volunteers immunized under chloroquine chemoprophylaxis with
Plasmodium falciparum
sporozoites (CPS) develop complete, long-lasting protection against homologous sporozoite challenge. Chloroquine affects neither sporozoites nor liver-stages, but kills only asexual forms in erythrocytes once released from the liver into the circulation. Consequently, CPS immunization exposes the host to antigens from both preerythrocytic and blood stages, and induced immunity might target either of these stages. We therefore explored the life cycle stage specificity of CPS-induced protection. Twenty-five malaria-naïve volunteers were enrolled in a clinical trial, 15 of whom received CPS immunization. Five immunized subjects and five controls received a sporozoite challenge by mosquito bites, whereas nine immunized and five control subjects received an i.v. challenge with
P. falciparum-
infected erythrocytes. The latter approach completely bypasses preerythrocytic stages, enabling a direct comparison of protection against either life cycle stage. CPS-immunized subjects (13 of 14) developed anticircumsporozoite antibodies, whereas only one volunteer generated minimal titers against typical blood-stage antigens. IgG from CPS-immunized volunteers did not inhibit asexual blood-stage growth in vitro. All CPS-immunized subjects (5 of 5) were protected against sporozoite challenge. In contrast, nine of nine CPS-immunized subjects developed parasitemia after blood-stage challenge, with identical prepatent periods and blood-stage multiplication rates compared with controls. Intravenously challenged CPS-immunized subjects showed earlier fever and increased plasma concentrations of inflammatory markers D-dimer, IFN-γ, and monokine induced by IFN-γ than i.v. challenged controls. The complete lack of protection against blood-stage challenge indicates that CPS-induced protection is mediated by immunity against preerythrocytic stages. However, evidence is presented for immune recognition of
P. falciparum
-infected erythrocytes, suggesting memory responses unable to generate functional immunity.
Modernization as Westernization? The geopolitical consequences of ethno-nationalism analyzed through Russian Art
Authors: Shah Tabish
Published: April 2013

This paper argues that ethno-nationalist models of state organization encourage and strengthen sectarianism by accentuating differences between respective majority populations and those with non-majority characteristics as problematic, and identifies and explains the impacts of this for intra-state security in the West and for building partnerships with non-Western populations, citing negative implications on how we understand political behavior and for influence in military operations. The paper uses nineteenth-century Russian identity as a case study, considers the conflation between modernization and Westernization occuring at the time and uses Russian Art of the period as an analytical tool to uncover nuances that are relevant to debates concerning security, identity, and political behavior.
“Soviet mentality?” The role of shared political culture in relations between the Armenian state and Russia's Armenian diaspora
Authors: Cavoukian Kristin
Published: April 2013

Russia's Armenians have begun to form diaspora institutions and engage in philanthropy and community organization, much as the pre-Soviet “established” diaspora in the West has done for years. However, the Russian Armenian diaspora is seen by Armenian elites as being far less threatening due to a shared “mentality.” While rejecting the mentality argument, I suggest that the relationship hinges on their shared political culture and the use of symbols inherited from the Soviet Union in the crafting of new diaspora and diaspora-management institutions. Specifically, “Friendship of the Peoples” symbolism appears to be especially salient on both sides. However, the difference between old and new diasporas may be more apparent than real. The Russian Armenian diaspora now engages in many of the same activities as the Western diaspora, including the one most troublesome to Armenia's elites: involvement in politics.
HAIR TYPES, POLLEN, AND SEED SURFACES OF SOLANUM MACROCARPON COMPLEX AND SOLANUM LINNAEANUM (SOLANACEAE)
Authors: Bukenya Z.R. , Carasco J.F.
Published: April 2013

Hair types, pollen, and seed surfaces ofSolanum macrocarponL. complex andSolanum linnaeanumHepper ex Jaeger were studied using a light and scanning electron microscope. The different hair types occurring in theS. macrocarponcomplex andS. linnaeanumcan be used to differentiate the various groups inS. macrocarponcomplex, andS. macrocarponfromS. linnaeanum.Pollen ofS. macrocarponcomplex was tricolporate, prolate spheroidal, and the surface ornamented. Pollen characters could not be used to differentiate groups belonging toS. macrocarponcomplex. Seed surface patterns were found to be similar inS. macrocarponcomplex andS. linnaeanum, and hence of little taxonomic value.
ECTOMYCORRHIZAL ASSOCIATIONS PROVEN FOR PINUS HALEPENSIS
Authors: Torres P. , Honrubia M.
Published: April 2013

Six new ectomycorrhizal associations with Pinus halepensis are described. These associations have been proven using the “pouch” method for in vitro synthesis of ectomycorrhizae. Morphological and anatomical characteristics of each association are presented.
CONTRIBUTIONS TO THE FLORA OF ISRAEL. VI. STIPAGROSTIS DRARII AND AMBROSIA CONFERTIFLORA AND TENUIFOLIA, NEW RECORDS FROM ISRAEL
Authors: Danin Avinoam
Published: April 2013

Stipagrostis drarii, found recently in sandy soils of the Arava Valley, is typical component of sandy soils in extreme desert areas. It is adapted to sand mobility by having the ability to overcome up to 50 cm of sand-cover by producing new shoots from the axillary buds of the leafy culm and adventive roots from nodes close to the new soil surface.

Two species ofAmbrosiawhich seem to be relatively new introductions to the flora of Israel are recorded here for the first time. It is not clear if these colonizing species will become established. However, judging from their way of dispersal by many small diaspores and efficient vegetative propagation they are potentially noxious weeds.
SELFING ABILITY AND MALE STERILITY IN SENECIO VERNALIS WALDST. ET KIT. (ASTERACEAE) FROM ISRAEL
Authors: Comes H.P.
Published: April 2013

Two major findings relating to the breeding system of Senecio vernalis from Israel are reported. First, isolation experiments failed to confirm the existence of a widespread, truly self-compatible and predominantly self-pollinating breeding system in Israeli populations of S. vernalis. However, a single S. vernalis plant derived from a natural stand at Jerusalem was found to be self- compatible and strongly self-pollinating. In its progeny, there were signs of inbreeding depression commonly associated with selfed offspring of outbreeding species. Selfing ability ratios in this progeny indicate a single dominant gene for selfing ability in S. vernalis. The implications of these observations for the origin of S. vulgaris are briefly discussed. Second, the occurrence of gynodioecy in S. vernalis populations from Israel is reported. Although male sterile plants are recognizable by the complete absence of pollen on their exposed stigmas, there probably exists a large amount of variation within and between plants for pollen production. Infertile pollen grains of male steriles differ in size, shape, and sculpturing from those of hermaphrodites. At the Mt. of Olives, in Jerusalem, the frequency of male steriles was found to be 9.1%. There is some preliminary evidence for differences in floret (= ovule) number between the two gender types. Although the inheritance of male sterility appears to be predominantly cytoplasmically controlled, additional mechanisms restoring male fertility have to be postulated to account for the data observed in one of the crosses. The male sterility system in S. vernalis should therefore be referred to as “nuclear-cytoplasmic.”
THE OCCURRENCE OF SENECIO VULGARIS L. VAR. VULGARIS AND S. × HELWINGII BEGER EX HEGI (S. VULGARIS × S. VERNALIS WALDST. ET KIT.) IN ISRAEL
Authors: Comes H.P.
Published: April 2013

Common Groundsel (Senecio vulgarisL. var.vulgaris(2n = 40)) is widespread in the northern hemisphere. In Israel, judging from a herbarium survey, records taken from the Israel Plant Information Center (ROTEM), and field studies, it has a restricted and widely disjunct pattern of geographical distribution, and, thus, is another example of the comparatively large group of weeds in Israel which are extremely stenochorous. The remarkable gaps in its distribution, from the Upper Golan to Mt. Carmel and to the Jerusalem area, are considered primarily to be the result of paleoclimatic changes, whereas its occurrence outside these centers of distribution is probably related to long-distance dispersal events. Natural hybridization ofS. vulgariswith its closest ally,S. vernalisWaldst. et Kit. (2n = 20), results in formation of their shortly ligulate and highly sterile hybrid,S. × helwingiiBeger ex Hegi (2n = 30), which is reported for the first time from the Israel area. Hybrid frequencies of 8.7 and 9.8%, respectively, were found in the two mixed populations examined in the Upper Golan. These are higher than previously reported for two localities of hybridization in Central Europe (1.1 and 1.5%), and probably indicate a closer genetic affinity ofS. vulgarisvar.vulgaristoS. vernalisfrom Israel than toS. vernalisfrom Central Europe. It is likely that reports of radiate variants ofS. vulgarisvar.vulgarisfrom the Israel area, none of which could be confirmed, refer toS. × helwingii.
COMPARATIVE ASSESSMENT OF GENETIC DIVERSITY IN WILD AND CULTIVATED BARLEY USING RIBOSOMAL DNA SPACER LENGTH VARIANTS
Authors: Ramamoorthy Jeyanthi , Chong Daniel K. , Chinnappa C.C.
Published: April 2013

Ribosomal DNA spacer length variants (slv) were used to compare the genetic diversity betweenHordeum spontaneum, the supposed progenitor of cultivated barley, and landraces of barley,H. vulgare, collected from three countries in the eastern Mediterranean region. A total of six rDNA slv and six slv phenotypes were observed. All six slv and phenotypes were found in both species. Nei's heterozygosity index was higher for landraces in all three countries. Landraces possessed slightly higher diversity thanH. spontaneum.Slv phenotype 1 (112, 104) was the most predominant type in both species, and the frequency distributions for the two species were similar. This suggests thatH. vulgareandH. spontaneumbelong to the same polymorphic species. Furthermore,H. spontaneumseen today in the eastern Mediterranean region might have been derived from an extinct two-rowed ancestor.
ADAPTATION VERSUS PRE-EXISTING RESISTANCE: AN INTERGENOTYPE ANALYSIS OF THE RESPONSE OF SORGHUM BICOLOR TO SALINITY
Authors: Amzallag G.Nissim , R. Lerner Henri
Published: April 2013

Developmental and physiological responses of 11 Sorghum bicolor (L.) Moench genotypes exposed for 3 weeks to a 150 mM NaCl-pretreatment were studied. Following the pretreatment, exposure to 300 mM NaCl resulted in a gradient of response between “adaptation to salinity” (increase in salinity tolerance) and “pre-existing resistance” (maintenance of original salinity tolerance). Level of adaptation of each genotype was quantified by determination of the mean relative growth rate of the shoot at 300 mM NaCl (). There was a positive correlation between and the following parameters during the process of adaptation: inhibition of growth, decrease of the shoot:root ratio, and shoot Na+ uptake. There were more pronounced physiological perturbations during adaptation than during the pre-existing resistance response to salinity. During the first 25 days of exposure to NaCl, inhibition of growth and shoot Na+ concentration were not correlated. The much lower value for the intergenotype coefficient of variation (ICV) for Na+ + K+ as compared to that for Na+ or K+ suggests that the sum of these ions is a parameter of physiological importance, and that these two ions were interdependent and partially interchangeable. It seems that Na+ + K+ + CI− were the main osmotica in the shoot of most genotypes. It is concluded that the nature of the response of the plant, rather than Na+ toxicity, was responsible for the effects of salinity on growth.
EFFECTS OF NICKEL SULFATE ON ROOT GROWTH AND NUCLEOLI IN ROOT TIP CELLS OF ALLIUM CEPA
Authors: Liu Donghua , Jiang Wusheng , Guo Lin , Hao Yuqing , Lu Cheng , Zhao Fengmei
Published: April 2013

The effects of different concentrations of nickel sulfate on root growth and nucleoli in root tip cells of Allium cepa were studied. The concentrations of nickel sulfate (NiSO4 · 7H2O) used were in the range of 10−7-10−1M. The results showed that nickel sulfate has a stimulatory effect on root growth at lower concentrations, and an inhibitory effect at higher concentrations. Nickel has toxic effects on nucleoli at higher concentrations. Phenomena we observed were irregularly shaped nucleoli, weaker silver staining reaction at the periphery of the nucleolus, and extrusion of nucleolar material from nuclei into the cytoplasm after treatment with higher concentrations of Ni.
FLOWERING AND POLLINATION REQUIREMENTS IN CEREUS PERUVIANUS CULTIVATED IN ISRAEL
Authors: Weiss J. , Nerd A. , Mizrahi Y.
Published: April 2013

The flowering and pollination requirements of Cereus peruvianus (L) Mill. (Cactaceae) were investigated in Beer Sheva, Israel, in a three-year-old plantation which had been established from seedlings, in order to domesticate this plant as a fruit crop. Plants flowered during the hot season (May-October), and flowers opened for one night only. Variations were observed in the flowers' opening time, with the early-opening plants beginning to open two hours before sunset, and the late-opening plants opening close to sunset. Flowers were visited only by day-active insects: the honey bee (Apis mellifera) and the carpenter bee (Xylocopa pubescens). The visitors' behavior indicated that they were involved in pollination. Early-opening flowers were visited both in the evening and in the morning, whereas late-openers were visited only in the morning. C. peruvianus was found to be self-incompatible, and fruit set did not occur when flowers were hand self-pollinated. Hand cross-pollination resulted in very high fruit set (92%) and heavy fruits with a high seed number. Fruit set, seed number, and fruit weight were lower in open-pollination than in hand cross-pollination. This indicates limited pollination or fertilization in open- pollination and might be related to the briefness of the bee visits, reduced pollen germinability, and stigma receptivity during part of the visit period.
TEMPERATURES AND ECOLOGICAL—GENETIC DIFFERENTIATION AFFECTING THE GERMINATION OF HORDEUM SPONTANEUM CARYOPSES HARVESTED FROM THREE POPULATIONS: THE NEGEV DESERT AND OPPOSING SLOPES ON MEDITERRANEAN MOUNT CARMEL
Authors: Gutterman Yitzchak , Nevo Eviatar
Published: April 2013

Ecological—genetic differentiation and dry storage temperatures regulate the germination of caryopses of Hordeum spontaneum, the wild type of cultivated barley. Freshly harvested caryopses of H. spontaneum in their spikelets (dispersal units) did not germinate, but separated embryos did. After dry storage for more than 68 days at high temperatures, caryopses in their dispersal units germinated. The degree of after-ripening (dormancy) was found to differ in the 3 local populations tested in this study. The highest germination occurred in caryopses collected from the northern-facing slope of Nahal Oren, Mount Carmel, the most humid habitat tested. An intermediate result was from the opposite southern-facing slope, and the lowest germination was observed in those from the Negev Desert near Sede Boker. The germination level of caryopses from spikelets stored dry at low temperatures such as −18 °C remained poor for a long time. The ecological significance of this study is discussed.
LEAF AND STEM ANATOMY OF SPECIES OF CYTISOPHYLLUM, CYTISUS, CHAMAECYTISUS, GENISTA, AND GENISTA SECT. TELINE (FABACEAE: GENISTEAE) AS AN AID FOR TAXONOMY
Authors: Norverto C.A. , González-Andrés F. , Ortiz J.M.
Published: April 2013

The leaf and stem anatomies of several shrubby species of theCytisus-Genistacomplex have been studied. The selected species have potential value for soil conservation and as feed for ruminants in the Mediterranean basin. The usefulness of anatomy for identification of such species and its value as an aid to clarify the taxonomy of the complex were examined. We conclude that leaf anatomy is of no taxonomic use at the generic and infrageneric level. On the other hand, stem anatomy presents systematic value. The presence or absence of ribs and the occurrence of vascular bundles within the ribs have proven useful to identify genera as well as to clarify the taxonomy of the complex at the generic level. The results support the generic arrangement proposed by Bisby (1981). Some species can be identified by the presence of peculiar stem anatomical traits.
IN MEMORIAM—MICHAEL EVENARI AND HIS DESERT SEED DISPERSAL AND GERMINATION STRATEGIES OF SPERGULAR DIANDRA COMPARED WITH SOME OTHER DESERT ANNUAL PLANTS INHABITING THE NEGEV DESERT OF ISRAEL
Authors: Gutterman Yitzchak
Published: April 2013

The late Professor Michael Evenari was a leader and agreat scientist with a very wide view and varied interests. Throughout the 26 years that I studied desert plants with Professor Evenari in the deserts of Israel and the Sinai Peninsula, he liked to summarize the seasonal field observations of seedling emergence with the words, “this particular year is a very special year.”

What are the reasons for such species' diversity, and what are the survival strategies of desert annuals'? Some species are common and others emerge only once in several years under unpredictable seasonal precipitation and massive seed consumption by ants. Escape dispersal strategies after maturation of the tiny, long-living seeds, and partial “opportunistic” germination strategies after only 10 mm of rain, are found in some common annuals such as Schismus arabicus and Spergularia diandra. Day lengthing seed maturation, and light and temperatures during seed wetting and germination, also affect their germinability. In S. diandra, nine types of seeds have been found (3 genotypes and 3 color phenotypes), which differ in coat structure, color, and germinability, and in Mesembryanthemum nodiflorum a position effect was found (3 groups of seeds in a capsule). The more opportunities for a small portion of seeds from the seed bank to germinate after several rainfalls, the greater the chances to germinate at suitable rain distribution. This enables these plants to develop and produce large numbers of seeds, even after a number of small rainfalls.
ECOLOGY OF LINEAR DUNES: II. DIFFERENTIAL DEMOGRAPHIC RESPONSES OF ANNUAL PLANTS TO LOCAL SCALE VARIATION IN SAND STABILITY
Authors: Kadmon Ronen
Published: April 2013

An experimental study was designed to investigate the demographic mechanisms by which annual plants inhabiting desert sand dunes respond to local gradients in the stability of the sand. The results indicated that individual plants emerging at different topographic positions along the dune experience different probabilities of survival and reproduction. The general trend observed was a decrease in seedling survival, plant biomass, fecundity, reproductive allocation, and fruit weight from the relatively stable, interdune corridor towards the unstable crest of the dune. However, all of these demographic responses were highly species-specific, indicating that coexisting annual species respond differentially to underlying patterns of spatial heterogeneity in the stability of the sand. These results suggest that local-scale spatial heterogeneity in sand stability may be important in promoting coexistence of desert sand dune annuals.
HAIRY ROOT TRANSFORMATION SYSTEM IN LARGE-SEEDED GRAIN LEGUMES
Authors: Siefkes-Boer H.J. , Noonan M.J. , Bullock D.W. , Conner A.J.
Published: April 2013

Hairy roots were produced on faba bean (Vicia faba L.) and chickpea (Cicer arietinum L.) plants by inoculation with Agrobacterium root-inducing strains. Examination of 14 plant genotypes and eight Agrobacterium strains in all possible combinations revealed specific strain/genotype interactions. Hairy root size and morphology differed substantially between faba bean and chickpea hairy roots. Sixty percent of chickpea hairy roots were 10–15 mm in length and forty percent, 15–25 mm. All were <1.0 mm in thickness. Sixty-three percent of faba bean hairy roots were 15–25 mm long and thirty-seven percent, 25–40 mm. All faba bean hairy roots were between 1.0 and 1.5 mm in thickness.
APPLICATION OF ALGAL BIOFERTILIZERS (AULOSIRA FERTILISSIMA TENUIS AND ANABAENA DOLIOLUM BHARDAWAJA) FOR SUSTAINED PADDY CULTIVATION IN NORTHERN INDIA
Authors: Dubey A.K. , Rai A.K.
Published: April 2013

Field trials were conducted to determine the effect of algal biofertilizers(Aulosira fertilissimaandAnabaena doliolum), alone or in combination with different doses of N-fertilizer (0–120 kg N/ha) supplied as urea, on biomass yield and nutritive value of rice. All doses of N-fertilizer, together withA. fertilissimaorA. doliolum, significantly increased plant height, number of tillers/hill, root length, leaf length, chlorophyll content, number of panicles/hill, number of seeds/ear, seed weight, grain yield, protein, and N content of grain. However, lower doses of N-fertilizer resulted in more efficient and rapid responses. Maximal qualitative improvement in rice production was found with 90 kg N/ha together with 12.5 kg/ha algal biofertilizer. The responses to these biofertilizers appear to be strain-specific since application ofA. fertilissimayielded better results than application ofA. doliolum.Application of the former saved about 25% of the chemical N-demand of the crop.
CONTRIBUTIONS TO THE FLORA OF ISRAEL. VIII. A NEW CYPERUS FROM ISRAEL, CYPERUS SHARONENSIS DANIN ET KUKKONEN SP. N.
Authors: Danin Avinoam , Kukkonen Ilkka
Published: April 2013

A new Cyperus (C. sharonensis) belonging to section Arenarii (Kunth) Jaub. et Spach basal, from the Sharon Plain of Israel, is described. It has a tuberous brachyblastic basal part terminating the underground stem, and scapous inflorescence on 70–130-cm-long leafless culm, and grows on shallow dunes of the coastal plain of northern Israel between Tel Aviv and the coast of Galilee. The leaves are wider and longer and the rhizome thicker than those of its few relatives which share the sandy habitats of coastal or desert areas of Israel. The longer nutlets, specific morphology of the nearly smooth surface, and roots that are not woolly, all differentiate the new species from its closest relative, C. capitatus Vandelli.
WHEAT EVOLUTION
Authors: Breiman Adina , Graur Dan
Published: April 2013

Many wild and cultivated wheat species are amphidiploid, i.e., they are polyploid species containing two or more distinct nuclear genomes, each with its own independent evolutionary history, but whose genetic behavior resembles that of diploids. Amphidiploidy has important evolutionary consequences in wheat. Since the beginning of this century different methods have been employed to identify the diploid donors of the coexisting genomes in the polyploids. To date, several of the genomic donors have been identified, and the search for the others has been narrowed down considerably. Molecular methodologies that are being increasingly used in studies aimed at reconstructing the evolutionary history of wheat species and their wild relatives have resolved many of the phylogenetic relationships among the various taxa.
EVALUATION OF METAL ION TOXICITY ON ROOT TIP CELLS BY THE ALLIUM TEST
Authors: Liu Donghua , Jiang Wusheng , Wang Wei , Zhai Lin
Published: April 2013

The effects of different concentrations of eleven different metals (aluminum chloride, chromium nitrate and potassium dichromate, lead nitrate, copper sulfate, manganous sulfate, cobaltous nitrate, zinc sulfate, magnesium sulfate, nickel sulfate, cadmium chloride, and mercuric chloride) on cell division and nucleoli in root tip cells of Allium cepa were studied. The results showed that the metal ions could, in varying degrees, cause chromosome, nucleus, and nucleolus irregularities, including c-mitosis, chromosome bridges, chromosome stickiness, irregularly shaped nuclei, micronuclei, irregularly shaped nucleoli, some silver-stained material scattered in the nucleus, the weakening of silver-staining reaction at the periphery of the nucleolus, and the release of nucleolar material from the nucleus into the cytoplasm. The Allium test may be useful for the rapid screening of chemicals involved in environmental problems.
PENNISETUM CLANDESTINUM HOCHST. EX CHIOV. (POACEAE), AN AFRICAN GRASS IN EUROPE
Authors: Herrero-Borgoñón Juan José , Cristóbal José Carlos , Crespo B. Manuel
Published: April 2013

Pennisetum clandestinumHochst, ex Chiov. is a grass native to Central and Eastern Africa, which is reported for the Iberian and European floras from materials collected in the littoral areas of both Alicante and Valencia provinces (eastern Spain). This plant is briefly described, and some ecological and phytosociological data are also reported.