Controle da vitrificação do cravo (Dianthus caryophyllus L.) in vitro

Low levels of benzyl adenine (BAP), low water potential of the growth medium and low humidity due to cotton covers, inhibited vitrification of carnation (Dianthus caryophyllus L.) in vitro. However, under these conditions, a low development of plants and a decrease in the multiplication ratio, were observed. High levels of amonium nitrate enhanced vitrification with an increase in the total soluble protein content. An inverse correlation was observed in the presence of high levels of calcium chloride. The latter was correlated to an increase in peroxidase activity. The results allowed the establishment of a protocol to control vitrification during carnation meristein growth, as follows: "Gelrite", 4 g/1; naphtalene acetic acid, 0.5 mg/l; BAP, 0.05 mg/l; normal dosis of MS salts; cotton covers. For in vitro multiplication the protocol should be altered to BAP, 0.5 mg/1; amoniuin nitrate 10.3 mM; calcium chloride 12.0 mM.Baixos níveis de benziladenina (BAP), baixo potencial de água no meio e baixa umidade condicionada por tampas de algodão foram capazes de inibir a vitrificação de cravo (Dianthus caryophyllus L.) cultivado In vitro, mas essas condições implicaram no baixo desenvolvimento das plantas e da taxa de propagação. Elevados níveis de NH4NO3 demonstraram serem altamente promotores da vitrifícação assinalada pelo alto conteúdo de proteína, enquanto relação inversa foi constatada para altos níveis de CaCl2, aos quais seguiu-se aumento na atividade da peroxidase. Os resultados permitiram estabelecer um protocolo para controle da vitrificação do cravo, constituído de 4,0 g/1 de "Gelrite", 0,5 mg/1 de ácido naftalenoacético (ANA), 0,05 mg/1 de BAP, doses normais das soluções salinas do meio MS e vedação do tipo tampas de algodão para cultivo de ápices meristemáticos. Para a fase de multiplicação, este protocolo deve ser alterado para 0,5 mg/1 de BAP, 10,3 mM de NH4NO3 e 12,0 mM de CaCl2

Evaluación genética en etapa de vivero de áreas productoras de semillas (APS) de Pino Ponderosa en Nordpatagonia

El Pino Ponderosa (Pinus ponderosa Dougl. ex Laws) es la principal especie forestal implantada en secanoen la Patagonia. Su potencialidad productiva y la disponibilidad de tierras para su cultivo permiten proyectarla continuidad de su uso en plantaciones comerciales, para lo que es indispensable asegurar la provisión desemillas de adecuada calidad genética. Las semillas utilizadas en la última década se produjeron en una seriede rodales mediante ensayos para evaluar su descendencia. El objetivo del presente trabajo es evaluar estosrodales ensayando su descendencia. En este primer reporte presentamos los resultados de una evaluaciónen etapa de vivero. Se ensayaron 31 procedencias locales seleccionadas (Áreas Productoras de Semillas,APS) en dos sitios, midiendo altura y diámetro a la altura del cuello en plantines de 2 años de edad. A través de análisis de la varianza se probó un claro efecto de interacción entre las APS y los sitios, y también diferencias entre las APS dentro de cada sitio. Seguidamente, se establecieron rankings de las APS por sitio y variable evaluada. A través de comparaciones de a pares se formaron grupos homogéneos. También se estimó la estabilidad genotípica de las APS por medio del cálculo de sus ecovalencias. Los resultados son aún preliminares, pero el haber probado diferencias en tan temprana edad nos alerta sobre la importancia de la procedencia de las semillas a utilizar para la producción comercial. Se espera que estas diferencias se acentúen en edades más avanzadas. Para probarlo, ya se han establecido ensayos de plantación

Multi-GeV Electron Spectrometer

The advance in laser plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular the upcoming experiments with the FLAME laser at LNF will enter the GeV regime with almost 1pC of electrons. From the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need to develop a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV) under still unknown angular divergences. Within the PlasmonX experiment at LNF a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence present unprecedented challenges in the design and construction of such a device. We will present the design considerations for this spectrometer and the first results from a prototype.Comment: 7 pages, 6 figures, submitted to NIM

Search for lepton-flavor violation at HERA

A search for lepton-flavor-violating interactions $e p \to \mu X$ and $e p\to \tau X$ has been performed with the ZEUS detector using the entire HERA I data sample, corresponding to an integrated luminosity of 130 pb^{-1}. The data were taken at center-of-mass energies, $\sqrt{s}$, of 300 and 318 GeV. No evidence of lepton-flavor violation was found, and constraints were derived on leptoquarks (LQs) that could mediate such interactions. For LQ masses below $\sqrt{s}$, limits were set on $\lambda_{eq_1} \sqrt{\beta_{\ell q}}$, where $\lambda_{eq_1}$ is the coupling of the LQ to an electron and a first-generation quark $q_1$, and $\beta_{\ell q}$ is the branching ratio of the LQ to the final-state lepton $\ell$ ($\mu$ or $\tau$) and a quark $q$. For LQ masses much larger than $\sqrt{s}$, limits were set on the four-fermion interaction term $\lambda_{e q_\alpha} \lambda_{\ell q_\beta} / M_{\mathrm{LQ}}^2$ for LQs that couple to an electron and a quark $q_\alpha$ and to a lepton $\ell$ and a quark $q_\beta$, where $\alpha$ and $\beta$ are quark generation indices. Some of the limits are also applicable to lepton-flavor-violating processes mediated by squarks in $R$-Parity-violating supersymmetric models. In some cases, especially when a higher-generation quark is involved and for the process $e p\to \tau X$, the ZEUS limits are the most stringent to date.Comment: 37 pages, 10 figures, Accepted by EPJC. References and 1 figure (Fig. 6) adde

Multijet production in neutral current deep inelastic scattering at HERA and determination of alpha_s

Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 < Q2 < 5000 GeV2. The data were taken at the ep collider HERA with centre-of-mass energy sqrt(s) = 318 GeV using the ZEUS detector and correspond to an integrated luminosity of 82.2 pb-1. Jets were identified in the Breit frame using the k_T cluster algorithm in the longitudinally invariant inclusive mode. Measurements of differential dijet and trijet cross sections are presented as functions of jet transverse energy E_{T,B}{jet}, pseudorapidity eta_{LAB}{jet} and Q2 with E_{T,B}{jet} > 5 GeV and -1 < eta_{LAB}{jet} < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant alpha_s(M_Z), determined from the ratio of the trijet to dijet cross sections, is alpha_s(M_Z) = 0.1179 pm 0.0013(stat.) {+0.0028}_{-0.0046}(exp.) {+0.0064}_{-0.0046}(th.)Comment: 22 pages, 5 figure

Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV using an integrated luminosity of 120 pb-1. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in terms of the coalescence model. The (anti)deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.

Photoproduction of D∗±D^{*\pm} mesons associated with a leading neutron

The photoproduction of $D^{*\pm} (2010)$ mesons associated with a leading neutron has been observed with the ZEUS detector in $ep$ collisions at HERA using an integrated luminosity of 80 pb$^{-1}$. The neutron carries a large fraction, {$x_L>0.2$}, of the incoming proton beam energy and is detected at very small production angles, {$\theta_n<0.8$ mrad}, an indication of peripheral scattering. The $D^*$ meson is centrally produced with pseudorapidity {$|\eta| 1.9$ GeV}, which is large compared to the average transverse momentum of the neutron of 0.22 GeV. The ratio of neutron-tagged to inclusive $D^*$ production is $8.85\pm 0.93({\rm stat.})^{+0.48}_{-0.61}({\rm syst.})\%$ in the photon-proton center-of-mass energy range {$130 <W<280$ GeV}. The data suggest that the presence of a hard scale enhances the fraction of events with a leading neutron in the final state.Comment: 28 pages, 4 figures, 2 table

Measurement of the open-charm contribution to the diffractive proton structure function

Production of D*+/-(2010) mesons in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb^{-1}. Diffractive events were identified by the presence of a large rapidity gap in the final state. Differential cross sections have been measured in the kinematic region 1.5 < Q^2 < 200 GeV^2, 0.02 < y < 0.7, x_{IP} < 0.035, beta 1.5 GeV and |\eta(D*+/-)| < 1.5. The measured cross sections are compared to theoretical predictions. The results are presented in terms of the open-charm contribution to the diffractive proton structure function. The data demonstrate a strong sensitivity to the diffractive parton densities.Comment: 35 pages, 11 figures, 6 table

Measurement of beauty production in deep inelastic scattering at HERA

The beauty production cross section for deep inelastic scattering events with at least one hard jet in the Breit frame together with a muon has been measured, for photon virtualities Q^2 > 2 GeV^2, with the ZEUS detector at HERA using integrated luminosity of 72 pb^-1. The total visible cross section is sigma_b-bbar (ep -> e jet mu X) = 40.9 +- 5.7 (stat.) +6.0 -4.4 (syst.) pb. The next-to-leading order QCD prediction lies about 2.5 standard deviations below the data. The differential cross sections are in general consistent with the NLO QCD predictions; however at low values of Q^2, Bjorken x, and muon transverse momentum, and high values of jet transverse energy and muon pseudorapidity, the prediction is about two standard deviations below the data.Comment: 18 pages, 4 figure

Measurement of charm fragmentation ratios and fractions in photoproduction at HERA

The production of D^*+, D^0, D^+, D_s^+ and Lambda_c^+ charm hadrons and their antiparticles in ep scattering at HERA was measured with the ZEUS detector using an integrated luminosity of 79 pb^-1. The measurement has been performed in the photoproduction regime with the exchanged-photon virtuality Q^2 < 1 GeV^2 and for photon-proton centre-of-mass energies in the range 130 < W < 300 GeV. The charm hadrons were reconstructed in the range of transverse momentum p_T(D, Lambda_c) > 3.8 GeV and pseudorapidity |eta(D, Lambda_c)| < 1.6. The production cross sections were used to determine the ratio of neutral and charged D-meson production rates, R_u/d, the strangeness-suppression factor, gamma_s, and the fraction of charged D mesons produced in a vector state, P_v^d. The measured R_u/d and gamma_s values agree with those obtained in deep inelastic scattering and in e^+e^- annihilations. The measured P_v^d value is smaller than, but consistent with, the previous measurements. The fractions of c quarks hadronising as a particular charm hadron, f(c -> D, Lambda_c), were derived in the given kinematic range. The measured open-charm fragmentation fractions are consistent with previous results, although the measured f(c -> D^*+) is smaller and f(c -> Lambda_c^+) is larger than those obtained in e^+e^- annihilations. These results generally support the hypothesis that fragmentation proceeds independently of the hard sub-process.Comment: 29 pages, 5 figures, 6 tables; minor text revision