Land CSEM impulse responses in simple layered models

We argue that in a half space model with a single layer, the electric field impulse response at different offsets can be understood physically. Diffusive fields travel along paths like wavefields but are not localised in time. Each event that is measured comes from a path with the least attenuation, which corresponds to early arrival. The most prominent TE mode contribution to the detection of a subsurface layer comes from the coupling of the airwave with the subsurface. The most prominent contribution from the TM mode comes from the path through the resistive layer with almost vertical diffusion paths between the surface and the target. The arrival time of the peak of the event from a conductive layer can be understood from this reasoning. The arrival time of the peak of the event from a resistive layer can be understood from this reasoning when the offset is not too large compared with burial depth of the target layer. These predictions lead to estimates of depth to target layer with an error of less than 5% and the resistivity of the resistive layer of less than 50%. The information contained in the impulse responses suggests that inversion would yield good results

Programa de ajuste multiparamétrico de curvas de titulação potenciométricas de ácidos húmicos Multiparametric adjustment program of potentiometric titration curves of humic acids

Tendo em vista a dificuldade de determinação dos pontos de inflexão na curva de titulação potenciométrica de ácidos húmicos, por metodologias tradicionais, foi desenvolvido foi desenvolvido um programa na linguagem Delphi para ajuste multiparamétrico de dados de titulação potenciométrica. Para isso um processo iterativo para estimar as raízes de um polinômio, com base no método de Newton-Raphson, foi utilizado. Os dados das titulações potenciométricas de ácidos húmicos usados nas regressões foram obtidos em um sistema automatizado de titulação potenciométrica. O programa desenvolvido na linguagem Delphi permite maior versatilidade e facilidade de operação, com uma interação mais amigável com o usuário. As curvas de titulação potenciométricas ajustadas sobrepuseram-se quase que totalmente às curvas experimentais. Os valores de pKa e as percentagens de grupos tituláveis dos ácidos húmicos, parâmetros ajustáveis na regressão multiparamétrica, apresentaram valores comparáveis com dados da literatura.<br>Regarding the difficulty of determining the inflection points in the potentiometric titration curve of humic acids by means of traditional methodologies, a Delphi program a Delphi program was developed for the multiparametric data adjustment in potentiometric titration. For this purpose, an iterative process was used, based on the Newton-Raphson method to estimate the roots of a polynomial. The humic acid potentiometric titration data, used in regressions, were obtained in an automated system of potentiometric titration. The program developed in Delphi language features greater versatility, ease of operation and better interaction with the user. The adjusted potentiometric titration curves overlap the experimental curves almost entirely. The pKa values and percentages of titrable groups of humic acids extracted from soil, adjustable parameters in the multiparametric regression, were comparable with those reported in the literature

A new route of magnetic biochar based polyaniline composites for supercapacitor electrode materials

In this paper, abundantly available durian's rind was opted as raw material to synthesize magnetic biochar in the presence of three different metallic salts by employing a novel vacuum condition in an electrical muffle furnace. Magnetic biochar was successfully produced with a maximum BET surface area value of 835 m2/g at the pyrolysis temperature and time of 800 °C and 25 min. This magnetic biochar was successfully employed to support and disperse polyaniline (PANI) particles for the application as supercapacitor electrode materials. The produced magnetic biochar - PANI composite exhibited an enhanced specific capacitance compared to the pure PANI and magnetic biochar. The highest specific capacitance of 615 F/g at 10 mV/s and energy density of 76.88 Wh/kg were demonstrated by the MBCA composite, which is considered favorably high compared to the existing PANI coated carbon composites. This magnetic biochar - PANI composites exhibits a good potential for future supercapacitor applications

A Deeper Look at DES Dwarf Galaxy Candidates: Grus I and Indus II

We present deep g- and r-band Magellan/Megacam photometry of two dwarf galaxy candidates discovered in the Dark Energy Survey (DES), Grus I and Indus II (DES J2038-4609). For the case of Grus I, we resolved the main sequence turn-off (MSTO) and similar to 2 mags below it. The MSTO can be seen at g(0) similar to 24 with a photometric uncertainty of 0.03 mag. We show Grus I to be consistent with an old, metal-poor (similar to 13.3 Gyr, [Fe/H] similar to -1.9) dwarf galaxy. We derive updated distance and structural parameters for Grus I using this deep, uniform, wide-field data set. We find an azimuthally-averaged halflight radius more than two times larger (similar to 151(-31)(+21) pc; similar to 4'. 16(-0.74)(+0.54)) and an absolute V-band magnitude similar to-4.1 that is similar to 1 magnitude brighter than previous studies. We obtain updated distance, ellipticity, and centroid parameters that are in agreement with other studies within uncertainties. Although our photometry of Indus II is similar to 2-3 magnitudes deeper than the DES Y1 public release, we find no coherent stellar population at its reported location. The original detection was located in an incomplete region of sky in the DES Y2Q1 data set and was flagged due to potential blue horizontal branch member stars. The best-fit isochrone parameters are physically inconsistent with both dwarf galaxies and globular clusters. We conclude that Indus II is likely a false positive, flagged due to a chance alignment of stars along the line of sight.ISSN:0004-637XISSN:2041-821

Core or Cusps:The Central Dark Matter Profile of a Strong Lensing Cluster with a Bright Central Image at Redshift 1

We report on SPT-CLJ2011-5228, a giant system of arcs created by a cluster at $z=1.06$. The arc system is notable for the presence of a bright central image. The source is a Lyman Break galaxy at $z_s=2.39$ and the mass enclosed within the 14 arc second radius Einstein ring is $10^{14.2}$ solar masses. We perform a full light profile reconstruction of the lensed images to precisely infer the parameters of the mass distribution. The brightness of the central image demands that the central total density profile of the lens be shallow. By fitting the dark matter as a generalized Navarro-Frenk-White profile---with a free parameter for the inner density slope---we find that the break radius is $270^{+48}_{-76}$ kpc, and that the inner density falls with radius to the power $-0.38\pm0.04$ at 68 percent confidence. Such a shallow profile is in strong tension with our understanding of relaxed cold dark matter halos; dark matter only simulations predict the inner density should fall as $r^{-1}$. The tension can be alleviated if this cluster is in fact a merger; a two halo model can also reconstruct the data, with both clumps (density going as $r^{-0.8}$ and $r^{-1.0}$) much more consistent with predictions from dark matter only simulations. At the resolution of our Dark Energy Survey imaging, we are unable to choose between these two models, but we make predictions for forthcoming Hubble Space Telescope imaging that will decisively distinguish between them.Comment: 13 Pages. Accepted for publication in Ap