Global existence for diffusion-electromigration systems in space dimension three and higher

We prove existence of global weak solutions for the Nernst-Planck-Poisson problem which describes the evolution of concentrations of charged species $X_1, ..., X_P$ subject to Fickian diffusion and chemical reactions in the presence of an electrical field, including in particular the Boltzmann statistics case. In contrast to the existing literature, existence is proved in any dimension. Moreover, we do not need the assumption $P = 2$ nor the assumption of equal diffusivities for all $P$ components. Our approach relies on the intrinsic energy structure and on an adequate nonlinear and curiously more regular approximate problem. The delicate passing to the limit is done in adequate functional spaces which lead to only weak solutions

Retrieving aerosol height from the oxygen A band: a fast forward operator and sensitivity study concerning spectral resolution, instrumental noise, and surface inhomogeneity

Hyperspectral radiance measurements in the oxygen A band are sensitive to the ver- tical distribution of atmospheric scatterers, which in principle allows to retrieve aerosol height from future instruments like TROPOMI, OCO2, FLEX, and CarbonSat. Discussed in this paper is a fast and flexible forward operator for the simulation of hy- perspectral radiances in the oxygen A band and, based on this scheme, a sensitivity study about the inversion quality of aerosol optical thickness, aerosol mean height, and aerosol type. The forward operator is based on a lookup table with efficient data com- pression based on principal component analysis. Linear interpolation and computation of partial derivatives is performed in the much smaller space of expansion coefficients rather then wavelength. Thus, this approach is computationally fast and at the same time memory efficient. The sensitivity study explores the impact of instrument design on the retrieval of aerosol optical thickness and aerosol height. Considered are signal to noise ratio, spectral resolution, and spectral sampling. Also taken into account are surface inhomogeneities and variations of the aerosol type

A Drosophila model for the role of epigenetics in brain function and development

A genetic study in Drosophila gives important insights into the epigenetic control of gene expression implicated in a human mental retardation syndrome

Forensic analysis of video file formats

AbstractVideo file format standards define only a limited number of mandatory features and leave room for interpretation. Design decisions of device manufacturers and software vendors are thus a fruitful resource for forensic video authentication. This paper explores AVI and MP4-like video streams of mobile phones and digital cameras in detail. We use customized parsers to extract all file format structures of videos from overall 19 digital camera models, 14 mobile phone models, and 6 video editing toolboxes. We report considerable differences in the choice of container formats, audio and video compression algorithms, acquisition parameters, and internal file structure. In combination, such characteristics can help to authenticate digital video files in forensic settings by distinguishing between original and post-processed videos, verifying the purported source of a file, or identifying the true acquisition device model or the processing software used for video processing

The noncommutative sine-Gordon breather

As shown in [hep-th/0406065], there exists a noncommutative deformation of the sine-Gordon model which remains (classically) integrable but features a second scalar field. We employ the dressing method (adapted to the Moyal-deformed situation) for constructing the deformed kink-antikink and breather configurations. Explicit results and plots are presented for the leading noncommutativity correction to the breather. Its temporal periodicity is unchanged.Comment: 1+9 pages, 2 figure

On Versatile Video Coding at UHD with Machine-Learning-Based Super-Resolution

Coding 4K data has become of vital interest in recent years, since the amount of 4K data is significantly increasing. We propose a coding chain with spatial down- and upscaling that combines the next-generation VVC codec with machine learning based single image super-resolution algorithms for 4K. The investigated coding chain, which spatially downscales the 4K data before coding, shows superior quality than the conventional VVC reference software for low bitrate scenarios. Throughout several tests, we find that up to 12 % and 18 % Bjontegaard delta rate gains can be achieved on average when coding 4K sequences with VVC and QP values above 34 and 42, respectively. Additionally, the investigated scenario with up- and downscaling helps to reduce the loss of details and compression artifacts, as it is shown in a visual example.Comment: Originally published as conference paper at QoMEX 202

Boosting Neural Image Compression for Machines Using Latent Space Masking

Today, many image coding scenarios do not have a human as final intended user, but rather a machine fulfilling computer vision tasks on the decoded image. Thereby, the primary goal is not to keep visual quality but maintain the task accuracy of the machine for a given bitrate. Due to the tremendous progress of deep neural networks setting benchmarking results, mostly neural networks are employed to solve the analysis tasks at the decoder side. Moreover, neural networks have also found their way into the field of image compression recently. These two developments allow for an end-to-end training of the neural compression network for an analysis network as information sink. Therefore, we first roll out such a training with a task-specific loss to enhance the coding performance of neural compression networks. Compared to the standard VVC, 41.4% of bitrate are saved by this method for Mask R-CNN as analysis network on the uncompressed Cityscapes dataset. As a main contribution, we propose LSMnet, a network that runs in parallel to the encoder network and masks out elements of the latent space that are presumably not required for the analysis network. By this approach, additional 27.3% of bitrate are saved compared to the basic neural compression network optimized with the task loss. In addition, we are the first to utilize a feature-based distortion in the training loss within the context of machine-to-machine communication, which allows for a training without annotated data. We provide extensive analyses on the Cityscapes dataset including cross-evaluation with different analysis networks and present exemplary visual results. Inference code and pre-trained models are published at https://github.com/FAU-LMS/NCN_for_M2M.Comment: 12 pages, 9 figures, 3 tables; This work has been accepted for IEEE T-CSVT special issue "Learned Visual Data Compression for both Human and Machine". Copyright may be transferred without notice, after which this version may no longer be accessibl

Communication Overhead of Network Coding Schemes Secure against Pollution Attacks

Network coding is a promising approach for increasing performance of multicast data transmission and reducing energy costs. Of course, it is essential to consider security aspects to ensure a reliable data transmission. Particularly, pollution attacks may have serious impacts in network coding since a single attacker can jam large parts of the network. Therefore, various approaches have been introduced to secure network coding against this type of attack. However, introducing security increases costs. Even though there are some performance analysis of secure schemes, to our knowledge there are no details whether these schemes are worthwhile to replace routing under the facet of efficiency. Thus, we discuss in this report parameters to assess the efficiency of secure network coding schemes. Using three network graphs, we evaluate parameters focusing on communication overhead for selected schemes. Our results show that there are still benefits in comparison to routing depending on the network topology

Tiller size/density compensation in Marandu palisadegrass swards

Este trabalho foi realizado para verificar a existência de relação entre tamanho e número de perfilhos em pastos de capim-marandu e testar se ajustes relacionados a variações em índice de área foliar (IAF), relação área foliar:volume por perfilho (R) e densidade aparente de perfilhos na equação de predição da resposta permitiriam explicar eventuais desvios da inclinação teórica predita. Foram avaliadas quatro condições da pastos (10, 20, 30 e 40 cm de altura), mantidas constantes por bovinos em regime de lotação contínua e taxa de lotação variável. O delineamento experimental foi o de blocos completos casualizados com quatro repetições. Avaliaram-se a densidade populacional de perfilhos, a massa por perfilho, a área foliar por perfilho, o índice de área foliar, a relação folha/colmo e a razão área foliar:volume do perfilho (R). Além disso, regressões lineares simples foram realizadas para a avaliação dos parâmetros da relação funcional entre densidade populacional e massa por perfilho. As medições foram realizadas de janeiro a dezembro de 2002. Pastos de capim-marandu possuem um mecanismo de compensação tamanho/densidade populacional de perfilhos pelo qual maiores densidades populacionais estão associadas a perfilhos pequenos e vice-versa. Os valores de R apresentaram variações sazonais, indicando que perfilhos desta espécie podem reduzir área foliar em relação ao seu volume como mecanismo de sobrevivência em condições de déficit hídrico. As análises de regressão revelaram coeficientes lineares menores que -3/2, de modo que os desvios desta expectativa foram explicados pelas variações registradas em IAF, R e na densidade aparente de perfilhos.The objectives of this study were to evaluate the existence of a relationship between tiller size and tiller number in grazed palisadegrass swards and to verify if adjustments related to changing in leaf area index (LAI), leaf area:tiller volume ratio (R), and tiller bulk density in the prediction equation of the response would explain eventual slope deviation from the theoretical predict slope. Treatments corresponded to four sward "steady state" conditions (10, 20, 30, and 40 cm sward surface heights), maintained by cattle under continuous but variable stocking rate. The experimental design was a complete randomized block design with four replicates and the response-variables evaluated were tiller population density, mean tiller weight, and leaf area per tiller. Sward leaf area index (LAI), tiller leaf:stem ratio, and tiller leaf area:volume ratio (R) were calculated and simple regression analyses between tiller population density and tiller weight in a logarithm scale were performed. Measurements were made from January to December 2002. Swards showed a tiller size/density compensation mechanism characterized by high tiller population densities associated with small tillers and vice-versa. R-values showed a seasonal pattern of variation, suggesting that tillers of this grass species would be able to reduce leaf area in relation to its volume as a response to water deficit conditions. Calculated regression coefficients were smaller than the theoretical expectation of -3/2 and such deviation was satisfactorily explained by the recorded variations in LAI, R and tiller bulk density.FAPES

Principal component analysis between morphogenetic and structural characteristics of Marandu palisadegrass swards under continuous stocking

A análise de componentes principais é uma técnica de análise multivariada que tem sido usada com pouca frequência na pesquisa com plantas forrageiras. Dessa forma, o objetivo do presente trabalho foi verificar se as hipóteses já testadas de acordo com técnicas univariadas podem ser validadas por meio de análise de componentes principais. Assim, duas análises foram realizadas. Na primeira, mais de 80% da variação do conjunto de dados foi explicada pelos primeiros três componentes principais, os quais relacionaram, basicamente, padrões de compensação tamanho/densidade populacional de perfilhos e discrepâncias na forma de se avaliar a forma do perfilho (relação folha: colmo ou razão área foliar: volume por perfilho). Na segunda, os três primeiros componentes principais explicaram 91,4% da variação total, relacionando-se, basicamente, com o processo de economia de recursos e alocação sazonal de assimilados para diferentes estruturas como forma de garantir sobrevivência e persistência das plantas na área. Os resultados mostram a potencialidade do uso da análise de componentes principais na interpretação de dados de pesquisa com plantas forrageiras. As conclusões obtidas são semelhantes àquelas obtidas com técnicas univariadas convencionais, com a vantagem de reduzir o número de variáveis globais em alguns poucos componentes principais.The principal component analysis is a multivariate analysis technique that has not been frequently used in the interpretation of research data on forage plants. Thus, the aim of this study was to use data already published and interpreted according to univariate analysis and verify if their hypotheses could also be validated through the principal component analysis. Two principal components analysis were performed. For the first one, the following variables were considered: tiller population density, individual tillers mass, leaf area index, leaf area/tiller volume ratio and tiller appearance and survival rates. In the first analysis more than 80% of of the data set variation was explained by the first three main components, which, basically, showed patterns of tiller size / density compensation mechanisms and revealed discrepancies in the way of evaluating tiller shape (leaf : stem ratio or leaf area: volume ratio per tiller). In the second analysis, the first three principal components explained 91.4% of the total variation, which was related basically to the process of resources economy and seasonal allocation of assimilates for different plant structures as a mean of ensuring survival and persistence of plants. The results show the potential of using the principal component analysis in the interpretation of research data on forage plants and corroborates conclusions obtained using univariate methods, with the advantage of reducing the number of global variable