Snow metamorphism: a fractal approach

Snow is a porous disordered medium consisting of air and three water phases: ice, vapour and liquid. The ice phase consists of an assemblage of grains, ice matrix, initially arranged over a random load bearing skeleton. The quantitative relationship between density and morphological characteristics of different snow microstructures is still an open issue. In this work, a three-dimensional fractal description of density corresponding to different snow microstructure is put forward. First, snow density is simulated in terms of a generalized Menger sponge model. Then, a fully three-dimensional compact stochastic fractal model is adopted. The latter approach yields a quantitative map of the randomness of the snow texture, which is described as a three-dimensional fractional Brownian field with the Hurst exponent H varying as continuous parameter. The Hurst exponent is found to be strongly dependent on snow morphology and density. The approach might be applied to all those cases where the morphological evolution of snow cover or ice sheets should be conveniently described at a quantitative level

ADVANCED DEEP LEARNING COMPARISONS FOR NON-INVASIVE TUNNEL LINING ASSESSMENT FROM GROUND PENETRATING RADAR PROFILES

Innovative, automated, and non-invasive techniques have been developed by scientific community to indirectly assess structural conditions and support the decision-making process for a worthwhile maintenance schedule. Nowadays, machine learning tools are in the spotlight because of their outstanding capabilities to deal with data coming from even heterogeneous sources and their ability to extract information from the structural systems, providing highly effective, reliable, and efficient damage classification tools. In the current study, a supervised multi-level damage classification strategy has been developed regarding Ground Penetrating Radar (GPR) profiles for the assessment of tunnel lining conditions. In previous research, the authors firstly considered a convolutional neural network (CNN), adopting the quite popular ResNet-50, initialized through transfer learning. In the present work, further enhancements have been attempted by adopting two configurations of the newest state-of-art advanced neural architectures: the neural transformers. The foremost is the original Vision Transformer (ViT), whose core is an encoder entirely based on the innovative self-attention mechanism and does not rely on convolution at all. The second is an improvement of ViT which merges convolution and self-attention, the Compact Convolution Transformer (CCT). In conclusion, a critical discussion of the different pros and cons of adopting the above-mentioned different architectures is finally provided, highlighting the actual powerfulness of these technologies in the future civil engineering paradigm nevertheless

Interpreting Methamphetamine Levels in a High-Use Community

Illicit drug use is a largely hidden phenomenon and population measures are notoriously problematic. Reliable and valid data for local, regional and national public health and other interventions are needed. To address this information we examined temporal trends within and across weeks in methamphetamine (MA) in a single location in order to inform a sampling plan for understanding long-term trends in MA use based on sampling raw influent to waste water treatment plants. The measured concentrations in wastewater are used to estimate the total mass of MA consumed MA rather than the number of doses due to the uncertainty surrounding methamphetamine purity, mass of MA per dose, and the number of doses used per day. Results from a region with high levels of MA use indicate that MA levels do not differ significantly between weekdays and weekends (p=0.1), consistent with a predominately regular, daily use pattern use. The potential contribution of legal sales of d- and l-MA to the mass of MA consumed within the community was estimated to range from 3-8%. Limitations and uncertainties associated with estimating the mass of MA consumption include small contributions of prescription and over-the-counter drugs that are metabolized to MA as well as measurement and sampling variability.Keywords: Temporal patterns, Epidemiology wastewater, Methamphetamine (MA)Keywords: Temporal patterns, Epidemiology wastewater, Methamphetamine (MA

Voltage control of nuclear spin in ferromagnetic Schottky diodes

We employ optical pump-probe spectroscopy to investigate the voltage dependence of spontaneous electron and nuclear spin polarizations in hybrid MnAs/n-GaAs and Fe/n-GaAs Schottky diodes. Through the hyperfine interaction, nuclear spin polarization that is imprinted by the ferromagnet acts on conduction electron spins as an effective magnetic field. We demonstrate tuning of this nuclear field from <0.05 to 2.4 kG by varying a small bias voltage across the MnAs device. In addition, a connection is observed between the diode turn-on and the onset of imprinted nuclear polarization, while traditional dynamic nuclear polarization exhibits relatively little voltage dependence.Comment: Submitted to Physical Review B Rapid Communications. 15 pages, 3 figure

Multipolar Interactions in the Anderson Lattice with Orbital Degeneracy

Microscopic investigation is performed for intersite multipolar interactions in the orbitally degenerate Anderson lattice, with CeB$_6$ taken as an exemplary target. In addition to the $f^0$ intermediate state, $f^2$ Hund's-rule ground states are included as intermediate states for the interactions. The conduction-band states are taken as plane waves and the hybridization as spherically symmetric. The spatial dependences of multipolar interactions are given by the relative weight of partial wave components along the pair of sites. It is clarified how the the anisotropy arises in the interactions depending on the orbital degeneracy and the spatial configuration. The stability of the $\Gamma_5$ antiferro-quadrupole order in the phase II of CeB$_6$ is consistent with our model. Moreover, the pseudo-dipole interactions follow a tendency required by the phenomenological model for the phase III.Comment: 30 pages, 4 figure

Environmental Emission of Pharmaceuticals from Wastewater Treatment Plants in the USA

The residual drugs, drug bioconjugates, and their metabolites, mostly from human and veterinary usage, are routinely flushed down the drain, and enter wastewater treatment plants (WWTP). Increasing population, excessive use of allopathic medicine, continual introduction of novel drugs, and existing inefficient wastewater treatment processes result in the discharge of large volumes of pharmaceuticals and their metabolites from the WWTPs into the environment. The effluent from the WWTPs globally contaminate ~25% of rivers and the lakes. Pharmaceuticals in the environment, as contaminants of emerging concerns, behave as pseudo-persistent despite their relatively short environmental half-lives in the environment. Therefore, residual levels of pharmaceuticals in the environment not only pose a threat to the wildlife but also affect human health through contaminated food and drinking water. This chapter highlights WWTPs as point-sources of their environmental emissions and various effects on the aquatic and terrestrial ecosystem

Steel fibre reinforced concrete for elements failing in bending and in shear

Discrete steel fibres can increase significantly the bending and the shear resistance of concrete structural elements when Steel Fibre Reinforced Concrete (SFRC) is designed in such a way that fibre reinforcing mechanisms are optimized. To assess the fibre reinforcement effectiveness in shallow structural elements failing in bending and in shear, experimental and numerical research were performed. Uniaxial compression and bending tests were executed to derive the constitutive laws of the developed SFRC. Using a cross-section layered model and the material constitutive laws, the deformational behaviour of structural elements failing in bending was predicted from the moment-curvature relationship of the representative cross sections. To evaluate the influence of the percentage of fibres on the shear resistance of shallow structures, three point bending tests with shallow beams were performed. The applicability of the formulation proposed by RILEM TC 162-TDF for the prediction of the shear resistance of SFRC elements was evaluated. Inverse analysis was adopted to determine indirectly the values of the fracture mode I parameters of the developed SFRC. With these values, and using a softening diagram for modelling the crack shear softening behaviour, the response of the SFRC beams failing in shear was predicted.Fundação para a Ciência e a Tecnologia (FCT

Caracterização do desequilíbrio de ligação em uma população de bovinos da raça Nelore.

Resumo: Tendo em vista a importância da estimação do desequilíbrio de ligação para a seleção genômica, o objetivo deste estudo foi estimar o desequilíbrio de ligação de uma população de bovinos da raça Nelore participantes do programa de melhoramento da ANCP. Foram utilizadas informações de 9.459 animais genotipados com um painel de alta densidade, totalizando 735.044 SNP?s, antes do controle de qualidade. A estimação do desequilíbrio de ligação foi realizada através do programa SNP1101. Os valores de LD observados para os cromossomos autossômicos variaram de 0,18 a 0,25. Para marcadores distanciados até 1 Kb a média de r² foi de 0,53 e para marcadores distanciados entre 90 e 100 Kb 0,14. Para MAF a média variou de 0,23 a 0,25, considerando MAF mínimo de 5%. Os resultados obtidos neste estudo indicam que, a densidade de marcadores utilizados foi capaz de detectar altos níveis de LD. Adicionalmente, conclui-se que marcadores distanciados até 50 Kb ainda detectam consideráveis níveis de LD. Abstract: Considering the importance of estimating linkage disequilibrium for genomic selection, the objective of this study was to estimate the linkage disequilibrium in a population of Nellore cattle participating in the ANCP breeding program. Information from 9,396 genotyped animals with a high density panel, totaling 735,044 SNP's before quality control were used. The estimation of linkage dissequilibrium (LD) was performed using the SNP1101 program. The mean LD values observed for the autosomal chromosomes ranged from 0.18 to 0.25. For markers distanced lower than 1 Kb the r² mean was 0.53, and for markers distanced between 90 and 100 Kb was 0.14. For MAF, the mean ranged from 0.23 to 0.25, a minimum MAF of 0.05 was considered. The results obtained in this study indicated that the density of markers used was able to detect high levels of LD. Additionally, for markers distanced up to 50 Kb, considerable levels of LD was detected

Trace analysis of environmental matrices by large-volume injection and liquid chromatography-mass spectrometry

The time-honored convention of concentrating aqueous samples by solid-phase extraction (SPE) is being challenged by the increasingly widespread use of large-volume injection (LVI) liquid chromatography–mass spectrometry (LC–MS) for the determination of traces of polar organic contaminants in environmental samples. Although different LVI approaches have been proposed over the last 40 years, the simplest and most popular way of performing LVI is known as single-column LVI (SC-LVI), in which a large-volume of an aqueous sample is directly injected into an analytical column. For the purposes of this critical review, LVI is defined as an injected sample volume that is ≥10% of the void volume of the analytical column. Compared with other techniques, SC-LVI is easier to set up, because it requires only small hardware modifications to existing autosamplers and, thus, it will be the main focus of this review. Although not new, SC-LVI is gaining acceptance and the approach is emerging as a technique that will render SPE nearly obsolete for many environmental applications.In this review, we discuss: the history and development of various forms of LVI; the critical factors that must be considered when creating and optimizing SC-LVI methods; and typical applications that demonstrate the range of environmental matrices to which LVI is applicable, for example drinking water, groundwater, and surface water including seawater and wastewater. Furthermore, we indicate direction and areas that must be addressed to fully delineate the limits of SC-LVI