Transporte de explosivos químicos sometidos a procesos de infiltración y evaporación en suelos

Es necesario conocer el destino y el transporte de Compuestos Explosivos Relacionados ( para evaluar la contaminación potencial y para proteger los suministros de agua potable de contaminantes tóxicos, desarrollar estrategias de remediación, y facilitar la detección de explosivos enterrados. En este estudio se desarrollaron seis experimentos para evaluar los efectos de la infiltración y evaporación en el transporte de químicos explosivos. Estos experimentos se realizaron en una columna cilíndrica de 100 cm de longitud empacada con arena homogénea, instrumentada con sensores de presión de aire y agua y puntos de muestreo para monitorear las condiciones hidráulicas y perfiles de concentración de ERCs en el suelo. Esta investigación estudió el comportamiento del transporte de ERCs en el suelo bajo diferentes condiciones ambientales, cuando se sometieron a la advección (movimiento de fluidos). Los resultados mostraron que el transporte de TNT (2,4,6 trinitrotolueno) y DNT (2,4 dinitrotolueno) está influenciado por la disolución (fuente-agua), la volatilización (agua-aire), y las limitaciones en la transferencia de masa por adsorción (agua-suelo). El movimiento hacia abajo con el agua infiltrada por lo general es retardado por procesos de adsorción en los suelos y superficies de contacto aire-agua. El movimiento ascendente del agua durante la evaporación resultó en el movimiento ascendente de ERCs hacia la superficie sueloatmósfera. La evaporación del agua cerca de la superficie del suelo produjo un aumento de la concentración de ERC cerca de la superficie del suelo después de períodos prolongados de evaporación

Photometry of the Type Ia Supernovae 1999cc, 1999cl, and 2000cf

We present previously unpublished BVRI photometry of the Type Ia supernovae 1999cc and 2000cf along with revised photometry of SN 1999cl. We confirm that SN 1999cl is reddened by highly non-standard dust, with R_V = 1.55 +/- 0.08. Excepting two quasar-lensing galaxies whose low values of R_V are controversial, this is the only known object with a published value of R_V less than 2.0. SNe 1999cl and 2000cf have near-infrared absolute magnitudes at maximum in good agreement with other Type Ia SNe of mid-range decline rates.Comment: 28 pages, 5 figures, accepted for publication in the Astronomical Journal, 5 November 200

Nonclassicality in Weak Measurements

We examine weak measurements of arbitrary observables where the object is prepared in a mixed state and on which measurements with imperfect detectors are made. The weak value of an observable can be expressed as a conditional expectation value over an infinite class of different generalized Kirkwood quasi-probability distributions. "Strange" weak values for which the real part exceeds the eigenvalue spectrum of the observable can only be found if the Terletsky-Margenau-Hill distribution is negative, or, equivalently, if the real part of the weak value of the density operator is negative. We find that a classical model of a weak measurement exists whenever the Terletsky-Margenau-Hill representation of the observable equals the classical representation of the observable and the Terletsky-Margenau-Hill distribution is nonnegative. Strange weak values alone are not sufficient to obtain a contradiction with classical models. We propose feasible weak measurements of photon number of the radiation field. Negative weak values of energy contradicts all classical stochastic models, whereas negative weak values of photon number contradict all classical stochastic models where the energy is bounded from below by the zero-point energy. We examine coherent states in particular, and find negative weak values with probabilities of 16% for kinetic energy (or squared field quadrature), 8% for harmonic oscillator energy and 50% for photon number. These experiments are robust against detector inefficiency and thermal noise.Comment: 12 pages, 8 figure

Quadratic reheating

The reheating process for the inflationary scenario is investigated phenomenologically. The decay of the oscillating massive inflaton field into light bosons is modeled after an out of equilibrium mixture of interacting fluids within the framework of irreversible thermodynamics. Self-consistent, analytic results for the evolution of the main macroscopic magnitudes like temperature and particle number densities are obtained. The models for linear and quadratic decay rates are investigated in the quasiperfect regime. The linear model is shown to reheat very slowly while the quadratic one is shown to yield explosive particle and entropy production. The maximum reheating temperature is reached much faster and its magnitude is comparable with the inflaton mass.Comment: 21 pages, LaTeX 2.09, 4 figures. To be published in International Journal of Modern Physics

Plant regeneration of tea (Camellia sinensis) by in vitro culture of meristems, axillary buds and uninodal segments

Tres tipos de explantes de dos clones ( C H 1 4 I N TA y C H 3 1 8 I N TA ) d e t é (Camellia sinensis (L.) O. Kuntze) fueron evaluados para su regeneración in vitro, bajo la influencia de dos citocininas (BAP y CIN) y una giberelina (AG3). Previa desinfección, con etanol 70% (1 minuto) e hipoclorito de sodio 1,5% (20 minutos) y tres enjuagues con agua destilada estéril, los explantes fueron aislados y cultivados en los distintos medios de cultivo. Las mejores respuestas en formación de vástagos se registraron con los segmentos uninodales de ambos clones cultivados en el medio ½ MS + 1 mg/L de BAP o con el cultivo de yemas axilares del clon CH 14 INTA en el medio ½ MS + 1 mg/L de BAP o del clon CH 318 INTA en el medio ½ MS + 1 mg/L BAP + 1 mg/L AG3. Los mejores resultados con el empleo de meristemas caulinares se obtuvieron en el medio ½ MS + 1 mg/L de CIN y 1 mg/L de AG3. Los vástagos obtenidos fueron enraizados mediante su cultivo en ¼ MS + 6 mg/L de IBA.Plants of two clones (CH 14 INTA and CH 318 INTA) of tea (Camellia sinensis (L.) O. Kuntze) were regenerated by in vitro culture of three types of explants disinfected by immersion in 70% ethanol (1 min) and 1.5% sodium hypochlorite (20 min). The best medium for shoot regeneration from uninodal segments, for both clones, as well as for axillary buds of CH 14 INTA clone was ½ MS + 1 mg/L BAP. While the best medium for axillary buds of CH 318 clone was ½ MS + 1 mg/L BAP + 1 mg/L AG3. For meristems culture, the best medium, for both clones was ½ MS + 1 mg/L KIN + 1 mg/L AG3. Rooting of regenerated shoots were achieved by culture them on ¼ MS + 6 mg/L IBA.Fil: Molina, Sandra P.. Instituto Nacional de Tecnología Agropecuaria (Argentina). Estación Experimental Agropecuaria Cerro AzulFil: Pérez, María Laura. Universidad Nacional del Nordeste. Facultad de Ciencias AgrariasFil: Rey, Hebe Y.. Universidad Nacional del Nordeste. Facultad de Ciencias AgrariasFil: Mroginski, Luis A.. Universidad Nacional del Nordeste. Facultad de Ciencias Agraria

Influence of water sample storage protocols in chemiluminescence detection of trace elements by batch or FI modes

[EN] This paper shows the influence of different sample storage protocols, on the chemiluminescence signal of some metal ions. The storage protocols studied were: acid addition (HCl or HNO3) and no reagent addition to filtered and refrigerated (T=4 °C) samples. Light emission was produced for the chemiluminescence reaction between luminol and hydrogen peroxide in buffer carbonate conditions (pH 10.8) catalysed by Cr(III), Co(II) and Cu(II). Batch and/or flow modes in different conditions were tested. Fe(II), Fe(III), Ni(II) and Mn(II) did not give chemiluminescence in the studied conditions. A parallel study of sensitivity and selectivity was performed. Then the presence or absence of the masking agent EDTA, added to samples or used in the carrier stream, is assayed. If the samples are acidified with HNO3, a previous neutralisation is needed using batch mode. The determination of Cr(III) is independent of storage protocol by flow injection (FI) method; however, the determination of Co(II) or Cu(II) or total determination of three metals requires the conditioning of standards. Detection limits achieved are ranged between 0.5 and 2 ¿g l¿1. For batch mode, detection limits are better for unacidified samples and worse for carbonate-neutralised samples. The influence of storage protocols was validated using standard metal mixtures and calibration solutions. The use of standard reference material (SRM© 1640) (Trace elements in natural water) corroborates the previous statements and validates the accuracy of the different approaches underlined. This paper demonstrates that it is possible to determine Cr(III) selectively in natural waters.The authors are grateful to the DGICYT (Project No. PB 97-1387) for financial support. Y.M.M., S.M.L. and L.A.T.G. express their gratitude to Ministerio de Educación y Cultura (Spain) for the predoctoral grant.Molliner Martínez, Y.; Meseguer-Lloret, S.; Tortajada-Genaro, LA.; Campins-Falcó, P. (2003). Influence of water sample storage protocols in chemiluminescence detection of trace elements by batch or FI modes. Talanta. 60(1):257-268. https://doi.org/10.1016/S0039-9140(03)00068-7S25726860

Contribution of water-limited ecoregions to their own supply of rainfall

The occurrence of wet and dry growing seasons in water-limited regions remains poorly understood, partly due to the complex role that these regions play in the genesis of their own rainfall. This limits the predictability of global carbon and water budgets, and hinders the regional management of naturalresources. Using novel satellite observations and atmospheric trajectory modelling, we unravel the origin and immediate drivers of growing-season precipitation, and the extent to which ecoregions themselves contribute to their own supply of rainfall. Results show that persistent anomalies in growing-season precipitation—and subsequent biomass anomalies—are caused by a complex interplay of land and ocean evaporation, air circulation and local atmospheric stability changes. For regions such as the Kalahari and Australia, the volumes of moisture recycling decline in dry years, providing a positive feedback that intensifies dry conditions. However, recycling ratios increase up to40%, pointing to the crucial role of these regions in generating their own supply of rainfall; transpiration in periods of water stress allows vegetation to partly offset the decrease in regional precipitation. Findings highlight the need to adequately represent vegetation–atmosphere feedbacks in models to predict biomass changes and to simulate the fate of water-limited regions in our warming climate

Phase Sensitivity of a Mach-Zehnder Interferometer

The best performance of a Mach-Zehnder interferometer is achieved with the input state |N_T/2 + 1>|N_T/2-1 > + |N_T/2 - 1>|N_T/2+1>, being N_T the total number of atoms/photons. This gives: i) a phase-shift error confidence C_{68%}=2.67/N_T with ii) a single interferometric measurement. Different input quantum states can achieve the Heisenberg scaling ~ 1/N_T but with higher prefactors and at the price of a statistical analysis of two or more independent measurements.Comment: 4 figure

Deciphering species-specific pollen tube guidance in Solanum

Small, secreted cysteine-rich proteins (CRPs)combine a highly stable cysteine spacing,ensuring conservation of their 3D structure andfunction, and hypervariable inter-cysteine blocks, allowing quick evolution of specific recognition domains. Interestingly, several CRPs were shown to control key pollen-pistil interactions in aspecies-specific way. The most emblematicexample is perhaps the LURE defensin-likefamily, controlling directional guidance of pollentubes (PTs) in Torenia and Arabidopsis.We chose wild potatoes (Solanum sect. Petota) asa case study to investigate the impact of rapidCRP divergence in plant speciation. Gathering ~200 close species with overlapping distribution areas, this taxon indeed exhibits strong reproductive isolation. Lab-on-a-chipmicrofluidic experiments carried out on 4 species show that species-preferential PT attraction is a key factor in this isolation. We suspect polymorphic CRPs to control this attraction. High-throughput sequencing technologies were applied to profile the ovule secretome as well as the reproductive transcriptomes of our 4 speciesof interest. To screen out candidate genes, we developped KAPPA, a sequence search algorithm specifically dedicated to CRPs, and obtained a set of 32 defensin-like groups expressed in ovules. Five promising chemoattractant candidates exhibiting (i) ovule-specific expression, (ii) down-regulation in guidance-defective ovules, and (iii) interspecific divergence were selectedfor further characterization. They are currently being investigated with on-gel assays and specific microfluidic devices tailored for Solanum PTs. This study will lead to a better understanding of CRP-mediated PT chemoattraction as one of the major species-specificity checkpoints that mustbe unlocked by pollen tubes in the pistil.Fil: Joly, V.. Institut de Recherche En Biologie Végétale; CanadáFil: Viallet, C.. Institut de Recherche En Biologie Végétale; CanadáFil: Liu, Y.. Institut de Recherche En Biologie Végétale; CanadáFil: Zaro, A.. Universidad de Barcelona; EspañaFil: Ceriotti, Luis Federico. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Matton, D. P.. Institut de Recherche En Biologie Végétale; CanadáEastern Regional MeetingMontrealCanadáCanadian Society of Plant BiologistsMcGill Universit