Dissolution and Precipitation of Gypsum in the Soil Under Irrigation

Two soils were used in this soil column study. Yolo loam soil a non- c al c areous, non-gypsiferous soil from central California and Vernal soil a calcareous soil from eastern Utah. Initial studies were conducted where the solubilities of pure CaC0 3 and CaS0 4 \u27 2H 2 0 were determined in the presence of Logan river water, a KCl solution (2.8 mmhos/cm) and a K 2 S0 4 solution (Z. 7 mmhos/cm). Gypsum was more soluble in the KCl solution than in the K Z S0 4 solution. The solubility product of both gypsum and lime were determined from the analytical data. The formation of CaS0 4 0 and caco 3 0 ion pairs were cons idered to be the most important complex ions pres ent. A reasonable agreement was observed between the theoretical values of K and the ca lculated K sp sp Essentially the same results were obtained when these waters were used in leaching the columns of Yolo and Vernal soil columns The solubility of gypsUJn was greatest usmg the KCl leaching\u27 solution and least using the K 2504 leaching solution. Logan river water gave intermediate values. Calcium carbonate was most soluble in the K 2504 leaching solution and les s in the KCl solution. It was found that measuring the ci+ concentration in the effluent was a more reliable index to steady state condition than using an electrical conductivity lneasurement. Unsaturated flow removed more salt per unit volume of effluent than saturated flow. The relative area method was used to analyze the effluent under saturated moisture flow. 2+ It was found that a certain amount of Ca derived from gypsum dissolution precipitated in the column as CaC0 3 . This amount 2+ , was greater than 15% of the Ca dlssolved from gypsum

Partonic Energy Loss and the Drell-Yan Process

We examine the current status of the extraction of the rate of partonic energy loss in nuclei from A dependent data. The advantages and difficulties of using the Drell-Yan process to measure the energy loss of a parton traversing a cold nuclear medium are discussed. The prospects of using relatively low energy proton beams for a definitive measurement of partonic energy loss are presented.Comment: 12 pages, 2 figure

Conducting polymer tattoo electrodes in clinical electro- and magneto-encephalography

Temporary tattoo electrodes are the most recent development in the field of cutaneous sensors. They have successfully demonstrated their performances in the monitoring of various electrophysiological signals on the skin. These epidermal electronic devices offer a conformal and imperceptible contact with the wearer while enabling good quality recordings over time. Evaluations of brain activity in clinical practice face multiple limitations, where such electrodes can provide realistic technological solutions and increase diagnostics efficiency. Here we present the performance of inkjet-printed conducting polymer tattoo electrodes in clinical electroencephalography and their compatibility with magnetoencephalography. The working mechanism of these dry sensors is investigated through the modeling of the skin/electrode impedance for better understanding of the biosignals transduction at this interface. Furthermore, a custom-made skin phantom platform demonstrates the feasibility of high-density recordings, which are essential in localizing neuropathological activities. These evaluations provide valuable input for the successful application of these ultrathin electronic tattoos sensors in multimodal brain monitoring and diagnosis

Meson Structure Functions in Valon Model

Parton distributions in a {\it{valon}} in the next-to-leading order is used to determine the patron distributions in pion and kaon. The validity of the valon model is tested and shown that the partonic content of the valon is universal and independent of the valon type. We have evaluated the valon distribution in pion and kaon, and in particular it is shown that the results are in good agreement with the experimental data on pion structure in a wide range of $x=[10^{-4},1]$Comment: 13 pages with 7 figures included, The manuscript is revised, figures are added and some errors are corrected. Accepted for publication in Physical Review

Color Screening and the Suppression of the Charmonium State Yield in Nuclear Reactions

We discuss the new data for the production of the $\psi'$ meson in pA collisions at 450 GeV at CERN-SPS (of the NA50-collaboration) [1]. We extract from the CERN data $\sigma(\psi' N)\approx 8$ mb under the assumption that the $\psi'$ is produced as a result of the space-time evolution of a point-like $c\bar c$ pair which expands with time to the full size of the charmonium state. In the analysis we assume the existence of a relationship between the distribution of color in a hadron and the cross section of its interaction with a nucleon. However, our result is rather sensitive to the pattern of the expansion of the wave packet and significantly larger values of $\sigma(\psi' N)$ are not ruled out by the data. We show that recent CERN data confirm the suggestion of [2] that color fluctuations of the strengths in charmonium-nucleon interaction are the major source of suppression of the $J/\psi$ yield as observed at CERN in both pA and AA collisions.Comment: 10 pages, 5 figures (one with color

Separation of \gamma/\pi^0 showers at high energies

We have designed and carried out simulation studies of a two layer Shower Maximum Detector diagonally off-set (SMD-dos) optimized for the separation of \pi^0 showers from \gamma showers in the 30 to 150 GeV energy range. For 90% \gamma acceptance the SMD-dos yields \pi^0 rejection efficiency of 92+-4%, 87+-4% and 32+-2%, respectively, for 30, 50 and 150 GeV incident energies. We find that the SMD-dos is superior to a conventional geometry single-layer or mutiple-layer shower maximum detector (SMD), of equal granularity, by an average factor of ~1.5 over the 50 to 150 GeV energy range. We also find that the SMD-dos gives better \pi^0 rejection, for the same number of channels, than a SMD. At hadron - hadron colliders the signature of choice for the detection of the Higgs particle, in the mass range of 120 to 160 GeV, is via the decay H-->\gamma\gamma. The addition of a SMD-dos to the planned detectors at the LHC would significantly reduce the background to the \gamma-signal coming from prolific \pi^0 production.Comment: 16 pages, 6 figures, LaTeX. Submitted to Nuclear Instruments and Method

J/Psi and Psi' total cross sections and formation times from data for charmonium suppression in pApA collisions

The recent data for E866 experiment on the x_F dependence for charmonium suppression in pA collisions at 800 GeV are analyzed using a time- and energy-dependent preformed charmonium absorption cross section \sigma_{abs}^\psi(\tau,\sqrt{s}). For \sqrt{s}=10 GeV the initially (\tau=0) produced premeson has an absorption cross section of \sigma_{pr}~3mb. At the same energy but for \tau -> \infty one deduces for the total cross sections \sigma_{tot}^{J/Psi N}=(2.8\pm 0.3)mb, \sigma_{tot}^{J/Psi N}= (10.5\pm 3.6)mb. The date are compatible with a formation time \tau_{1/2}=0.6 fm/c.Comment: 13 pages of Latex including 2 figures; typos in the abstract are correcte

J/ψJ/\psi suppression in Pb+Pb collisions and pTp_T broadening

We have analysed the NA50 data, on the centrality dependence of $p_T$ broadening of $J/\psi$'s, in Pb+Pb collisions, at the CERN-SPS. The data were analysed in a QCD based model, where $J/\psi$'s are suppressed in 'nuclear' medium. Without any free parameter, the model could explain the NA50 $p_T$ broadening data. The data were also analysed in a QGP based threshold model, where $J/\psi$ suppression is 100% above a critical density. The QGP based model could not explain the NA50 $p_T$ broadening data. We have also predicted the centrality dependence of $J/\psi$ suppression and $p_T$ broadening at RHIC energy. Both the models, the QGP based threshold model and the QCD based nuclear absorption model, predict $p_T$ broadening very close to each other.Comment: The paper was completely revised. The conclusion is also changed. 5 pages, 4 figure

Modèle de génération simultanée des signaux EEG de surface et de profondeur

Ce travail porte sur l'interprétation des signaux électroencéphalographiques (EEG) et stéréo-électroencéphalographiques (SEEG) acquis chez des patients épileptiques candidats à la chirurgie. Cette question est abordée au travers d'une modélisation réaliste des signaux EEG et SEEG, qui repose sur une représentation physiologiquement pertinente des sources de l'activité cérébrale associant un modèle biophysique de sources dipolaires et un modèle biomathématique de populations neuronales. Les signaux induits sur les capteurs de surface et de profondeur sont ensuite obtenus par la résolution du problème direct dans le volume conducteur de la tête. Le modèle complet permet d'étudier les relations existant entre la configuration spatio-temporelle des sources d'activité et les propriétés des signaux observés en surface et en profondeur