Suitability of short-period sensors for retrieving reliable H/V peaks for frequencies less than 1 Hz

Using three different short-period electromagnetic sensors with resonant frequencies of 1 Hz (Mark L4C-3D), 2 Hz (Mark L-22D), and 4.5 Hz (I/O SM-6), coupled with three digital acquisition system, the PDAS Teledyne Geotech, the REFTEK 72A, and the Earth Data Logger PR6-24 (EDL), the effect of the seismic instruments on the horizontal-to-vertical spectral ratio (H/V) using seismic noise for frequencies less than 1 Hz has been evaluated. For all possible sensors - acquisition system pairs, the background seismic signal and instrumental self-noise power spectral densities have been calculated and compared. The results obtained when coupling the short-period sensors with different acquisition systems show that the performance of the considered instruments at frequencies < 1 Hz strongly depends upon the sensor-acquisition system combination and the gain used, with the best performance obtained for sensors with the lowest resonance frequency. For all acquisition systems, it was possible to retrieve correctly the H/V peak down to 0.1-0.2 Hz by using a high gain and a 1 Hz sensor. In contrast, biased H/V spectral ratios were retrieved when low-gain values were considered. Particular care is required when using 4.5 Hz sensors since they may not even allow the fundamental resonance frequency peak to be reproduce

Consensus Protein Design without Phylogenetic Bias

Consensus design is an appealing strategy for the stabilization of proteins. It exploits amino acid conservation in sets of homologous proteins to identify likely beneficial mutations. Nevertheless, its success depends on the phylogenetic diversity of the sequence set available. Here, we show that randomization of a single protein represents a reliable alternative source of sequence diversity that is essentially free of phylogenetic bias. A small number of functional protein sequences selected from binary-patterned libraries suffice as input for the consensus design of active enzymes that are easier to produce and substantially more stable than individual members of the starting data set. Although catalytic activity correlates less consistently with sequence conservation in these extensively randomized proteins, less extreme mutagenesis strategies might be adopted in practice to augment stability while maintaining function

Suitability of short-period sensors for retrieving reliable H/V peaks for frequencies less than 1 Hz

Using three different short-period electromagnetic sensors with resonant frequencies of 1 Hz (Mark L4C-3D), 2 Hz (Mark L-22D), and 4.5 Hz (I/O SM-6), coupled with three digital acquisition system, the PDAS Teledyne Geotech, the REFTEK 72A, and the Earth Data Logger PR6-24 (EDL), the effect of the seismic instruments on the horizontal-to-vertical spectral ratio (H/V) using seismic noise for frequencies less than 1 Hz has been evaluated. For all possible sensors - acquisition system pairs, the background seismic signal and instrumental self-noise power spectral densities have been calculated and compared. The results obtained when coupling the short-period sensors with different acquisition systems show that the performance of the considered instruments at frequencies < 1 Hz strongly depends upon the sensor-acquisition system combination and the gain used, with the best performance obtained for sensors with the lowest resonance frequency. For all acquisition systems, it was possible to retrieve correctly the H/V peak down to 0.1-0.2 Hz by using a high gain and a 1 Hz sensor. In contrast, biased H/V spectral ratios were retrieved when low-gain values were considered. Particular care is required when using 4.5 Hz sensors since they may not even allow the fundamental resonance frequency peak to be reproduce

Harmonic Generation from Relativistic Plasma Surfaces in Ultra-Steep Plasma Density Gradients

Harmonic generation in the limit of ultra-steep density gradients is studied experimentally. Observations demonstrate that while the efficient generation of high order harmonics from relativistic surfaces requires steep plasma density scale-lengths ($L_p/\lambda < 1$) the absolute efficiency of the harmonics declines for the steepest plasma density scale-length $L_p \to 0$, thus demonstrating that near-steplike density gradients can be achieved for interactions using high-contrast high-intensity laser pulses. Absolute photon yields are obtained using a calibrated detection system. The efficiency of harmonics reflected from the laser driven plasma surface via the Relativistic Oscillating Mirror (ROM) was estimated to be in the range of 10^{-4} - 10^{-6} of the laser pulse energy for photon energies ranging from 20-40 eV, with the best results being obtained for an intermediate density scale-length

Ground-based off-line aerosol measurements at Praia, Cape Verde, during the Saharan Mineral Dust Experiment: Microphysical properties and mineralogy

A large field experiment of the Saharan Mineral Dust Experiment (SAMUM) was performed in Praia, Cape Verde, in January and February 2008. This work reports on the aerosol mass concentrations, size distributions and mineralogical composition of the aerosol arriving at Praia. Three dust periods were recorded during the measurements, divided by transitional periods and embedded in maritime-influenced situations. The total suspended particle mass/PM10/PM2.5 were 250/180/74μg/m3 on average for the first dust period (17–21 January) and 250/230/83μg/m3 for the second (24–26 January). The third period (28 January to 2 February) was the most intensive with 410/340/130 μg/m3. Four modes were identified in the size distribution. The first mode (50–70 nm) and partly the second (700–1100 nm) can be regarded as of marine origin, but some dust contributes to the latter. The third mode (2–4 μm) is dominated by advected dust, while the intermittently occurring fourth mode (15–70 μm) may have a local contribution. The dust consisted of kaolinite (dust/maritime period: 35%wt./25%wt.),K-feldspar (20%wt./25%wt.), illite (14%wt./10%wt.), quartz (11%wt./8%wt.), smectites (6%wt./4%wt.), plagioclase (6%wt./1%wt.), gypsum (4%wt./7%wt.), halite (2%wt./17%wt.) and calcite (2%wt./3%wt.)

Exploring the impact of the inverse Faraday effect on all-optical helicity-dependent magnetization switching

All-optical helicity-dependent magnetization switching (AO-HDS) is the quickest deterministic technique for data storage by solely using ultrashort laser pulses. Granular high data density magnetic storage media developed for heat-assisted magnetic recording (HAMR) provide an ideal playground to investigate the interplay of effects leading to magnetization switching. In the latest perception, we identify two effects, the magnetic circular dichroism (MCD) and the inverse Faraday effect (IFE), as the forces driving the switching process. During photon absorption, which leads to a rapid temperature rise and thus to magnetization quenching, the MCD ensures two distinct electron temperatures due to helicity-dependent absorption. This effect already holds a nonvanishing probability for magnetization switching. At the same time, the IFE induces a magnetic moment within the material, enhancing the switching probability. We present AO-HDS experiments using ultrashort laser pulses ($\lesssim 200\,\mathrm{fs}$) in the near-infrared range from $800\,\mathrm{nm}$ to $1500\,\mathrm{nm}$. The experiments demonstrate a strong dependence of the switching efficiency on the absorbed energy density, elevating the electron temperature in the vicinity of the Curie point, allowing for the IFE to take full effect, inducing a magnetic moment for deterministic switching in the quenched magnetization state. While we do not observe an enhanced switching due to an increased MCD, a higher induced magnetization usually improves the switching rate if the electron temperature reaches the transition temperature vicinity. Therefore, we conclude that the magnetic moment generated by the IFE is crucial for the switching efficiency and the distinct deterministic character of the switching process. Laser pulses with a higher absorption induce a higher magnetic moment and switch magnetization at lower fluences

Molecular Characterization of Chimeric Staphylococcus aureus Strains from Waterfowl

Staphylococcus aureus is a versatile pathogen that does not only occur in humans but also in various wild and domestic animals, including several avian species. When characterizing S. aureus isolates from waterfowl, isolates were identified as atypical CC133 by DNA microarray analysis. They differed from previously sequenced CC133 strains in the presence of the collagen adhesin gene cna; some also showed a different capsule type and a deviant spa type. Thus, they were subjected to whole-genome sequencing. This revealed multiple insertions of large regions of DNA from other S. aureus lineages into a CC133-derived backbone genome. Three distinct strains were identified based on the size and extent of these inserts. One strain comprised two small inserts of foreign DNA up- and downstream of oriC; one of about 7000 nt or 0.25% originated from CC692 and the other, at ca. 38,000 nt or 1.3% slightly larger one was of CC522 provenance. The second strain carried a larger CC692 insert (nearly 257,000 nt or 10% of the strain’s genome), and its CC522-derived insert was also larger, at about 53,500 nt or 2% of the genome). The third strain carried an identical CC692-derived region (in which the same mutations were observed as in the second strain), but it had a considerably larger CC522-like insertion of about 167,000 nt or 5.9% of the genome. Both isolates of the first, and two out of four isolates of the second strain also harbored a hemolysin-beta-integrating prophage carrying “bird-specific” virulence factors, ornithine cyclodeaminase D0K6J8 and a putative protease D0K6J9. Furthermore, isolates had two different variants of SCC elements that lacked mecA/mecC genes. These findings highlight the role of horizontal gene transfer in the evolution of S. aureus facilitated by SCC elements, by phages, and by a yet undescribed mechanism for large-scale exchange of core genomic DNA

The heterogeneous coma of comet 67P/Churyumov-Gerasimenko as seen by ROSINA: H <inf>2</inf> O, CO <inf>2</inf>, and CO from September 2014 to February 2016

Context. The ESA Rosetta mission has been investigating the environment of comet 67P/Churyumov-Gerasimenko (67P) since August 2014. Among the experiments on board the spacecraft, the ROSINA experiment (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) includes two mass spectrometers to analyse the composition of neutrals and ions and a COmet Pressure Sensor (COPS) to monitor the density and velocity of neutrals in the coma. Aims. We study heterogeneities in the coma during three periods starting in October 2014 (summer in the northern hemisphere) and ending in February 2016 (end of winter in the northern hemisphere). We provide a detailed description of the main volatiles dynamics (H2O, CO2, CO) and their abundance ratios. Methods. We analysed and compared the data of the Reflectron-Type Time-Of-Flight (RTOF) mass spectrometer with data from both the Double Focusing Mass Spectrometer (DFMS) and COPS during the comet escort phase. This comparison has demonstrated that the observations performed with each ROSINA sensor are indeed consistent. Furthermore, we used a Direct Simulation Monte Carlo (DSMC) model to compare modelled densitites with in situ detections. Results. Our analysis shows how the active regions of the main volatiles evolve with the seasons with a variability mostly driven by the illumination conditions; this is the case except for an unexpected dichotomy suggesting the presence of a dust layer containing water deposited in the northern hemisphere during previous perihelions hiding the presence of CO2. The influence of various parameters is investigated in detail: distance to the comet, heliocentric distance, longitude and latitude of sub-satellite point, local time, and phase angle