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Seismic measuring stations do not only record seismic waves. They also pick up tremors caused by other factors: these are known as seismic background noise. In normal conditions, this environmental background is steady over a long time. This article presents the influence of high reduction of human activity due to COVID-19 initial lockdown on ground vibration in the Large Hadron Collider tunnel at the European Organization for Nuclear Research.

Seismic measuring stations do not only record seismic waves. They also pick up tremors caused by other factors: these are known as seismic background noise. In normal conditions, this environmental background is steady over a long time. This article presents the influence of high reduction of human activity due to COVID-19 initial lockdown on ground vibration in the Large Hadron Collider tunnel at the European Organization for Nuclear Research.

Abstract Background A previous laboratory study involving wild type, mutant and devR/dosR complemented strains of Mycobacterium tuberculosis reported the attenuation phenotype of complemented strain, Comp1. This phenotype was intriguing since the parental strain H37Rv, devR mutant (Mut1) and additional complemented strains, Comp9 and Comp11, were virulent in the guinea pig model. Results Towards deciphering the mechanism underlying the attenuation of Comp1, a whole genome sequencing approach was undertaken. Eight Single Nucleotide Polymorphisms (SNPs) unique to the Comp1 strain were identified. Of these, 5 SNPs were non-synonymous and included a G➞A mutation resulting in a W1591Stop mutation in ppsD gene of the phthiocerol dimycocerosate (PDIM) biosynthetic cluster. Targeted sequence analysis confirmed this mutation in only Comp1 strain and not in wild type (H37Rv), devR knockout (Mut1) or other complemented (Comp9 and Comp11) bacteria. Differential expression of the PDIM locus in Comp1 bacteria was observed which was associated with a partial deficiency of PDIM, an increased sensitivity to detergent and a compromised ability to infect human THP-1 cells. Conclusions It is proposed that a spontaneous mutation in the ppsD gene of Comp1 underlies down-modulation of the PDIM locus which is associated with defects in permeability and infectivity as well as virulence attenuation in guinea pigs. Our study demonstrates the value of whole genome sequencing for resolving unexplainable bacterial phenotypes and recommends the assessment of PDIM status while assessing virulence properties of laboratory-manipulated strains of M. tuberculosis.

Robustness against geometric distortion is one of the crucial important issues in watermarking. The discrete Fourier transform (DFT)-based watermarking methods have been proposed to address this issue. However, the effect of the well-known “periodization artifact” caused by the DFT transform limits their application. In this paper, a novel watermarking scheme is proposed. This scheme is based on the periodic plus smooth image decomposition (PPSD). The PPSD is a simple and efficient way to deal with periodization artifacts arising from the use of the DFT transform on 2-D images. It consists in the decomposition of the discrete image into a periodic component that gathers most of the image information but avoids periodization artifacts, and a smooth (harmonic) component that presents very slow variations inside the image. The algorithm is evaluated in terms of imperceptibility and robustness. The experiments indicate that our developed PPSD technique can achieve high imperceptibility while showing good robustness to various kinds of attacks, including geometrical distortions. [ABSTRACT FROM AUTHOR]

Abstract: Pleistocene periglacial slope deposits (PPSD) almost completely cover the mountainous regions of Germany and are the parent material for soil formation. It is therefore necessary to map their thickness and spatial distribution. The mapping of periglacial slope deposits can be performed more quickly than conventional probing by drilling or soil profile analysis if ground penetrating radar (GPR) is used. Because the use of GPR to map soils or soil depth depends to a large degree on the suitability of soil properties, the performance of GPR in mapping layered substrates was evaluated at a test site with varying water content and substrate properties. We focus on the efficiency of GPR in mapping loess-rich layers above layers with a high stone content within a depth range of 1 m. Different materials such as loess, metabasalt and slates, including heavily weathered slates (saprolite) were studied. The test site was equipped with several time domain reflectometry (TDR) probes to monitor soil water content changes for the period of one year. Systematic investigations of the reflection patterns were performed with 100, 200, 400, 500 and 900 MHz antennae with respect to the quality of measurement, dielectric coefficient and soil water content of different material combinations. It became clear that the 400 MHz antenna is most suitable for creating images of loess and stone layers at the depth range of 1 m and under natural climatic conditions. The results prove that the most important effect the substrates at the test site have on GPR is produced by the differences in water content of bordering layers, making the soil water capacity of the materials a decisive parameter for evaluating GPR performance. The water content dependent dielectric permittivities show higher values for saprolite (heavily weathered slate) compared to loess by a factor of 1.3 to 2, with water content increasing from 15 to 40 vol.% respectively. In doing so we discovered the dielectric permittivity of loess to be 1.2 to 1.5 times higher than that of unweathered slate at the same water content. We were able to locate horizontal layer boundaries at the test site starting at a minimum of 0.5 vol.% water content difference and a reflection coefficient r ≥0.02 between the layers. The results obtained at the test site show the ability of GPR to detect layering in PPSD at different water contents and help to predict the performance of GPR measurements in mapping of PPSD. [Copyright &y& Elsevier]

Background: A previous laboratory study involving wild type, mutant and devR/dosR complemented strains of Mycobacterium tuberculosis reported the attenuation phenotype of complemented strain, Comp1. This phenotype was intriguing since the parental strain H37Rv, devR mutant (Mut1) and additional complemented strains, Comp9 and Comp11, were virulent in the guinea pig model. Results: Towards deciphering the mechanism underlying the attenuation of Comp1, a whole genome sequencing approach was undertaken. Eight Single Nucleotide Polymorphisms (SNPs) unique to the Comp1 strain were identified. Of these, 5 SNPs were non-synonymous and included a G➞A mutation resulting in a W1591Stop mutation in ppsD gene of the phthiocerol dimycocerosate (PDIM) biosynthetic cluster. Targeted sequence analysis confirmed this mutation in only Comp1 strain and not in wild type (H37Rv), devR knockout (Mut1) or other complemented (Comp9 and Comp11) bacteria. Differential expression of the PDIM locus in Comp1 bacteria was observed which was associated with a partial deficiency of PDIM, an increased sensitivity to detergent and a compromised ability to infect human THP-1 cells. Conclusions: It is proposed that a spontaneous mutation in the ppsD gene of Comp1 underlies down-modulation of the PDIM locus which is associated with defects in permeability and infectivity as well as virulence attenuation in guinea pigs. Our study demonstrates the value of whole genome sequencing for resolving unexplainable bacterial phenotypes and recommends the assessment of PDIM status while assessing virulence properties of laboratory-manipulated strains of M. tuberculosis. [ABSTRACT FROM AUTHOR]