Pressurized irrigation

En un área de aprox. 2 000 000 ha del sur de Córdoba (Argentina) se evaluaron los equipos de riego con el fin de conocer su funcionamiento, el grado de uniformidad con que trabajan y la eficiencia de riego lograda por los productores. Se realizaron 21 evaluaciones sobre equipos operando de acuerdo con la programación establecida por sus usuarios; 14 sobre pivote, una sobre avance lateral, 4 sobre enrolladores (3 de cañón y uno de baja presión) y 2 sobre side roll. Los parámetros de calidad de riego brindaron coeficiente medio de uniformidad = 81,4 %, con uniformidad de distribución = 73,23 %. En el 80 % de los casos, la lámina aplicada fluctuó entre 10 y 20 mm siendo su promedio = 17 mm. De los resultados se puede inferir que -en general- la superficie asignada a cada equipo es siempre mayor que su capacidad para realizar oportunamente una óptima reposición del agua al suelo y que, si bien los coeficientes de uniformidad y distribución del agua pueden considerarse aceptables, la programación del riego es mala en todos los establecimientos evaluados poniéndose de manifiesto en la baja eficiencia de almacenamiento y repercutiendo directamente sobre la producción de los cultivos regados.In approx. 2 000 000 ha in the South of Córdoba (Argentina) was evaluated the performance of the irrigation equipments, the way they are operated and employed, the degree of uniformity they work and the efficiency of irrigation obtained by the farmers. There were 21 evaluations of equipments operating according to the irrigation program established by the owners, 14 on pivots, 1 on lateral move, 4 rollers (3 for gun sprinkler and 1 with low pressure) and 2 side roll. The parameters of the quality of irrigation show values of uniformity coefficient of 81.4 % with a uniformity of distribution of 73.23 %. The 80 % of the cases present a applied depth between 10 and 20 mm with a average value of 17 mm. Based on the obtained values, it can be assumed that -in general- the surface assigned to each of the equipments, is always larger than its capacity to replace soil water adequately. Although the uniformity coefficient and water distribution can be considered acceptable, the most important aspect that highlights this study is the bad irrigation scheduling in all the evaluated farms, stated in the low efficiency of soil water storage that affects directly the production of the irrigated crops.Fil: Puiatti, Juan M. P..Fil: Crespi, Raúl Jesús.Fil: Rivetti, Ana Rosa

"CMAD", a Full Custom ASIC, for the Upgrade of COMPASS RICH-1

An 8 channel, full-custom ASIC prototype, named ”CMAD”, designed for the readout of the RICH-I detector system of the COMPASS experiment at CERN is presented. The task of the chip is amplifying the signals coming from fast multi-anode photomultipliers and comparing them against a threshold adjustable on-chip on a channel by channel basis. CMAD, developed using a 350nm commercial CMOS technology, occupies an area of 4.7x3.2mm2 and consumes 26mW/Ch power from a 3.3 V single source

Modeling DNA beacons at the mesoscopic scale

We report model calculations on DNA single strands which describe the equilibrium dynamics and kinetics of hairpin formation and melting. Modeling is at the level of single bases. Strand rigidity is described in terms of simple polymer models; alternative calculations performed using the freely rotating chain and the discrete Kratky-Porod models are reported. Stem formation is modeled according to the Peyrard-Bishop-Dauxois Hamiltonian. The kinetics of opening and closing is described in terms of a diffusion-controlled motion in an effective free energy landscape. Melting profiles, dependence of melting temperature on loop length, and kinetic time scales are in semiquantitative agreement with experimental data obtained from fluorescent DNA beacons forming poly(T) loops. Variation in strand rigidity is not sufficient to account for the large activation enthalpy of closing and the strong loop length dependence observed in hairpins forming poly(A) loops. Implications for modeling single strands of DNA or RNA are discussed.Comment: 15 pages, 17 figures, submitted to Eur. J. Phys.

A low-noise CMOS front-end for TOF-PET

An analogue CMOS front-end for triggering and amplification of signals produced by a silicon photomultiplier (SiPM) coupled to a LYSO scintillator is proposed. The solution is intended for time-of-flight measurement in compact Positron Emission Tomography (TOF-PET) medical imaging equipments where excellent timing resolution is required (approximate to 100 ps). A CMOS 0.13 mu m technology was used to implement such front end, and the design includes preamplification, shaping, baseline holder and biasing circuitry, for a total silicon area of 500x90 mu m. Waveform sampling and time-over-threshold (ToT) techniques are under study and the front-end provides fast and shaped outputs for time and energy measurements. Post layout simulation results show that, for the trigger of a single photoelectron, the time jitter due to the pre-amplifier noise can be as low as 15 ps (FWHM), for a photodetector with a total capacitance of 70 pF. The very low input impedance of the pre-amplifier (approximate to 5 Omega) allows 1.8 ns of peaking time, at the cost of 10 mW of power consumption

Functional characterization of the type I toxin Lpt from Lactobacillus rhamnosus by fluorescence and atomic force microscopy

Lpt is a 29 amino acid long type I toxin identified in the plasmid DNA of wild Lactobacillus rhamnosus strains isolated from food. We previously reported that transcription of the encoding gene was upregulated under nutritional starvation conditions mimicking cheese ripening environment. The heterologous expression of the Lpt peptide in E. coli resulted in cell growth inhibition, nucleoid condensation and compromised integrity of the cell membrane. Fusion of the Lpt peptide with the fluorescent protein mCherry allowed to visualize the accumulation of the peptide into the membrane, while mutagenesis experiments showed that either the insertion of a negatively charged amino acid into the hydrophobic a-helix or deletion of the hydrophilic C-terminal region, leads to a non-toxic peptide. AFM imaging of Lpt expressing E. coli cells has revealed the presence of surface defects that are compatible with the loss of portions of the outer membrane bilayer. This observation provides support for the so-called "carpet" model, by which the Lpt peptide is supposed to destabilize the phospholipid packing through a detergent-like mechanism leading to the removal of small patches of bilayer through micellization

Front end electronics for pixel detector of the PANDA MVD

ToPix 2.0 is a prototype in a CMOS 0.13 ¹m technology of the front-end chip for the hybrid pixel sensors that will equip the Micro-Vertex Detector of the PANDA experiment at GSI. The Time over Threshold (ToT) approach has been employed to provide a high charge dynamic range (up to 100 fC) with a low power dissipation (15 ¹W/cell). In an area of 100¹m£100¹m each cell incorporates the analog and digital electronics necessary to amplify the detector signal and to digitize the time and charge information. The ASIC includes 320 pixel readout cells organized in four columns and a simplified version of the end of column readout

Beam test results of the irradiated Silicon Drift Detector for ALICE

The Silicon Drift Detectors will equip two of the six cylindrical layers of high precision position sensitive detectors in the ITS of the ALICE experiment at LHC. In this paper we report the beam test results of a SDD irradiated with 1 GeV electrons. The aim of this test was to verify the radiation tolerance of the device under an electron fluence equivalent to twice particle fluence expected during 10 years of ALICE operation.Comment: 6 pages,6 figures, to appear in the proceedings of International Workshop In high Multiplicity Environments (TIME'05), 3-7 October 2005, Zurich,Switzerlan

Test results of the front-end system for the Silicon Drift Detectors of ALICE

The front-end system of the Silicon Drift Detectors (SDDs) of the ALICE experiment is made of two ASICs. The first chip performs the preamplification, temporary analogue storage and analogue-to-digital conversion of the detector signals. The second chip is a digital buffer that allows for a significant reduction of the connection from the front-end module to the outside world. In this paper, the results achieved on the first complete prototype of the front-end system for the SDDs of ALICE are presented

Relation of study quality, concordance, take home message, funding, and impact in studies of influenza vaccines: systematic review

Objective To explore the relation between study concordance, take home message, funding, and dissemination of comparative studies assessing the effects of influenza vaccines