Effect of positional inaccuracies on multielectrode results

This paper investigates the effect of electrode positioning errors on the inverted pseudosection. Instead of random spacing errors (as usually assumed in geoelectrics) we exactly measured this effect among field conditions. In the field, in spite of the greatest possible care, the electrode positions contain some inaccuracy: either in case of dense undergrowth, or varied topography, or very rocky field. In all these cases, it is not possible to put the electrodes in their theoretical position. As a consequence, the position data will contain some error. The inaccuracies were exactly determined by using a laser distance meter. The geometrical data from real field conditions and by using Wenner-α, Wenner-β, pole-dipole and pole-pole arrays were then considered over homogeneous half space. As we have found, the positioning errors can be regarded as insignificant, even in case of relatively uncomfortable field conditions. However, in case of very rocky surface the distortions are more significant, but it is still possible to make some corrections: either by neglecting a few electrode positions with the greatest positioning error, or to minimize the inline errors, even on the price that offline deviations are high

Influence of salicylic acid on phytochelatin synthesis in Zea mays during Cd stress

Abstract: Presoaking maize (Zea mays) seeds in salicylic acid (SA) reduces damage caused by cadmium. In the present work the possible role of phytochelatins (PCs) in SA-mediated protection against Cd toxicity was investigated. Seeds were presoaked in 0.5 mM SA, and seedlings were grown in hydroponic solution containing 0, 0.01, 0.015, or 0.025 mM Cd. Treatment with Cd increased the PC levels in maize roots, but only slight changes were observed in the leaves. Long-term exposure to Cd decreased the phytochelatin synthase (PCS) activity in the roots and led to an increase in PCS and glutathione reductase (GR) activities in maize leaves. Although presoaking seeds in SA solution before exposure to Cd may reduce the level of heavy metal injury and has an effect on the composition of individual PCs, this protection is not directly connected with the altered regulation of PCs

The two-ball bounce problem

A popular classroom demonstration is revisited in which a light ball and a much larger heavier ball are vertically aligned and dropped together onto a hard surface. Careful experimental data obtained using a high-speed camera is compared to a lumped-mass Newtonian restitution model. Good macroscopic agreement is found, provided there is sufficient separation between the two balls as they are dropped. An alternative continuum model based on elastic membrane theory is developed to explain the limit in which the balls are initially touching. The model assumes the lower ball deforms to a truncated sphere upon its impact with the floor, exciting an elastic wave which subsequently launches the upper ball like a particle on a trampoline, before the lower ball leaves the ground. A favourable comparison with experimental data is found for the case of negligible initial separation between the balls.</jats:p

Agroforestry research and development in Hungary

PosterHungary is a traditionally agricultural country, therefore the „old” agroforestry technologies (windbreaks, shelter-belts, hedgerows, wooded pastures) had been applied in large scale in the past centuries. From the early nineties the positive trend of increasing area of protective forest belts first stopped, then reversed. The former area of forest belts (35 000 hectares) has decreased by 50% up to this time. The high ratio of “risky” territories demonstrates the strong need for the development of rural areas, by eg. the implementation of innovative agricultural technology able to increase social-economic sustainability. Followed from the forest belt research project started in the ’60s and ran over the course of several decades, a new line of experiments has started some years ago in the UWH Faculty of Forestry with the aim to develop a modell for the design and construction of forest belts by the combination of digital modelling and field sampling with analytical methods. The examination and development of windbreaks and shelter belt system will be continued within the frame of a national project focused on climate – vegetation relationship. In 2012 the UWH Cooperational Research Centre, together with local cooperatives and farmers have set the objective of integrating modern agroforestry technologies in their on-farm agricultural activity and establishing new experimental sites available for future research and demonstration purposes. This cooperation will also contribute to the „AGFORWARD” international research project on agroforestry. In the Corvinus University of Budapest, Department of Ecological Farming and Sustainable Production Systems an R&D project on forest gardens started in 2010. From this year agroforestry appears among the “determinative research and development subjects” of the Ministry of Rural Development. This development and the increasing number of research projects show agroforestry rising again in Hungary

Magnetization and susceptibility of ferrofluids

A second-order Taylor series expansion of the free energy functional provides analytical expressions for the magnetic field dependence of the free energy and of the magnetization of ferrofluids, here modelled by dipolar Yukawa interaction potentials. The corresponding hard core dipolar Yukawa reference fluid is studied within the framework of the mean spherical approximation. Our findings for the magnetic and phase equilibrium properties are in quantitative agreement with previously published and new Monte Carlo simulation data.Comment: 8 pages including 4 figure

Discovery of the spectroscopic binary nature of three bright southern Cepheids

We present an analysis of spectroscopic radial velocity and photometric data of three bright Galactic Cepheids: LR Trianguli Australis (LR TrA), RZ Velorum (RZ Vel), and BG Velorum (BG Vel). Based on new radial velocity data, these Cepheids have been found to be members of spectroscopic binary systems. The ratio of the peak-to-peak radial velocity amplitude to photometric amplitude indicates the presence of a companion for LR TrA and BG Vel. IUE spectra indicate that the companions of RZ Vel and BG Vel cannot be hot stars. The analysis of all available photometric data revealed that the pulsation period of RZ Vel and BG Vel varies monotonically, due to stellar evolution. Moreover, the longest period Cepheid in this sample, RZ Vel, shows period fluctuations superimposed on the monotonic period increase. The light-time effect interpretation of the observed pattern needs long-term photometric monitoring of this Cepheid. The pulsation period of LR TrA has remained constant since the discovery of its brightness variation. Using statistical data, it is also shown that a large number of spectroscopic binaries still remain to be discovered among bright classical Cepheids.Comment: 9 pages, 14 figure

DNA-protein nanocomposites: Microscale structures with molecular precision

DNA is unique in its programmability and addressability. The ability of complementary sequences of DNA to recognize and bind to each other makes it an almost universal tool for controlling the assembly of nanoscale objects over small distances. DNA origami [1] is a particularly powerful self-assembly approach, serving to create breadboards on which to assemble nanostructures, but is limited to length scales below 100 nm. Attempts to extend its spatial scale lead to structures that assemble with poor yields, and for which size and mechanical rigidity must be traded off against one another. Here, we present a new paradigm for producing large, micrometer-scale structures, whilst maintaining the precision and programmability offered by DNA. We show that poor yields are a result of having too many unique components in the self-assembling system [2], and that poor mechanical rigidity is an intrinsic limitation of DNA. We overcome these limitations by using RecA, a DNA-binding protein, to increase the stiffness of our DNA nanostructures. The composite RecA-DNA structure has a persistence length almost an order of magnitude greater than that of double-stranded DNA (dsDNA) alone. RecA also acts as a generic component in our self-assembly scheme, since it binds in a non-sequence specific way to dsDNA. In addition, once one RecA monomer binds to dsDNA, the binding probability for other monomers increases. This cooperative binding feature means that any region of dsDNA becomes completely and uniformly coated with protein with almost perfect yield. We can thus build large, rigid structures in this way. To maintain our ability to address the structure with molecular precision, we create small origami breadboards at specific locations within the larger structure. In this way, we minimize the number of unique components involved in the assembly process, and therefore the number of pathways by which an incorrect structure can form. Our approach enables us to create micrometer-scale structures with molecular precision [4]. Please click Additional Files below to see the full abstract

InSight Aerothermal Environment Assessment

The Mars Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft, which successfully touched down on the planet surface on November 26, 2018, was proposed as a near build-to-print copy of the Mars Phoenix vehicle to reduce the overall cost and risk of the mission. Since the lander payload and the atmospheric entry trajectory were similar enough to those of the Phoenix mission, it was expected that the Phoenix thermal protection material thickness would be sufficient to withstand the entry heat load. However, allowances were made for increasing the heatshield thickness because the planned spacecraft arrival date coincided with the Mars dust storm season. The aftbody Thermal Protection System (TPS) components were not expected to change. In a first for a US Mars mission, the aerothermal environments for InSight included estimates of radiative heat flux to the aftbody from the wake. The combined convective and radiative heat fluxes were used to determine if the as-flown Phoenix thermal protection system (TPS) design would be sufficient for InSight. Although the radiative heat fluxes on the aftbody were predicted to be comparable to, or even higher than the local convective heat fluxes, all analyses of the aftbody TPS showed that the design would still be adequate. Aerothermal environments were computed for the vehicle from post-flight reconstruction of the atmosphere and trajectory and compared with the design environments. These comparisons showed that the predicted as-flown conditions were less severe than the design conditions