An experimental approach on calcarenite reservoir dilation factor

The time of flight of a plane wavefront generated from an acoustic pulse is expected to decrease when the medium length between the wave emitter and receiver is shortened. This simple idea is extrapolated to the case of reservoir compaction in order to obtain a geophysical parameter R (dilation factor) that relates the rock deformation to the variation of time of flight (also called time-lapse time shift in 4D seismics) or acoustic velocity of a plane wave propagating in the same direction of deformation. Interpretation of a few laboratory compressive tests with simultaneous ultrasonic acquisition, performed on oil-saturated calcarenite samples, are presented and discussed. The samples were subjected to several stress regimes and simultaneous ultrasonic acquisitions. Despite the formerly ultrasonic acquisition rate limitations, it was possible to obtain R values for various lateral-vertical stress ratios for each sample's linear and nonlinear stress-strain trends.

Colonization and Authentication of the Pyrethroid-Resistant Anopheles gambiae s.s. Muleba-Kis Strain; an Important Test System for Laboratory Screening of New Insecticides

Background: The emergence and spread of insecticide resistance in malaria vectors to major classes of insecticides call for urgent innovation and application of insecticides with novel modes of action. When evaluating new insecticides for public health, potential candidates need to be screened against both susceptible and resistant mosquitoes to determine efficacy and to identify potential cross-resistance to insecticides currently used for mosquito control. The challenges and lessons learned from establishing, maintaining, and authenticating the pyrethroid-resistant An. gambiae s.s. Muleba-Kis strain at the KCMUCo-PAMVERC Test Facility are described in this paper. Methods: Male mosquitoes from the F1 generation of wild-pyrethroid resistant mosquitoes were cross-bred with susceptible female An. gambiae s.s. Kisumu laboratory strain followed by larval selection using a pyrethroid insecticide solution. Periodic screening for phenotypic and genotypic resistance was done. WHO susceptibility tests and bottle bioassays were used to assess the phenotypic resistance, while Taqman™ assays were used to screen for known target-site resistance alleles (kdr and ace-1). Additionally, the strains were periodically assessed for quality control by monitoring adult weight and wing length. Results: By out-crossing the wild mosquitoes with an established lab strain, a successful resistant insectary colony was established. Intermittent selection pressure using alphacypermethrin has maintained high kdr mutation (leucine-serine) frequencies in the selected colony. There was consistency in the wing length and weight measurements from the year 2016 to 2020, with the exception that one out of four years was significantly different. Mean annual wing length varied between 0.0142–0.0028 mm compared to values obtained in 2016, except in 2019 where it varied by 0.0901 mm. Weight only varied by approximately 0.001 g across four years, except in 2017 where it differed by 0.005 g. Routine phenotypic characterization on Muleba-Kis against pyrethroids using the WHO susceptibility test indicated high susceptibility when type I pyrethroids were used compared to type II pyrethroids. Dynamics on susceptibility status also depended on the lapse time when the selection was last done. Conclusions: This study described the procedure for introducing, colonizing, and maintaining a resistant An. gambiae s.s. strain in the laboratory with leucine to serine substitution kdr allele which reflects the features of the wild-resistant population in East Africa. Challenges in colonizing a wild-resistant mosquito strain were overcome by out-crossing between mosquito strains of desired traits followed by intermittent insecticide selection at the larval stage to select for the resistant phenotype.

Medicine Delivery Bot Using Time Series and Object Detection

Nowadays, delivery is mainly done by humans which includes a lot of manual work. The existing way is good but lacks faster deliveries. In the present context the deliveries are not possible 24*7 by humans, especially in the case of medicines, customers often require immediate deliveries for maintaining their course of medication. Since, in many other fields AI has contributed to decreasing a lot of manual work and time. In this research paper, we have proposed the idea of a delivery bot which uses deep learning algorithms to detect traffic lights and classify the color of the traffic light. On the basis of which the lapse time will be calculated in between the two traffic lights and hence maps the route for delivery with the help of geocoding accordingly which helps in more secure and faster deliveries.

Temporal variation in scattering and intrinsic attenuation due to earthquakes in East Asia

Separated attenuation values have not been used in post-seismic variation research, although the scattering attenuation (Qs−1) parameter that can be used to estimate crustal inhomogeneity due to cracks. In this study, three earthquakes that occurred in Kumamoto (M7.3), Tottori (M6.6), and Gyeongju (M5.8) in 2016 were investigated by applying a multiple lapse time window analysis to seismograms recorded before and after the events. At a low frequency, significantly greater variation of the Qs−1 value was observed than the intrinsic attenuation (Qi−1) for the Kumamoto earthquake, whereas similarly large variation was observed for the Gyeongju earthquake. For the surrounding Kumamoto earthquake area of increased attenuation, even higher decreases in Qs–1 and Qi–1 were also observed. The increases occurred within a two year-period after mainshock. The large increases in attenuation, corresponding to regions with high peak ground acceleration, were limited to the basin area with an elevation below 500 m. Furthermore, post-seismic increases in attenuation values were found to correlate with the magnitude and length of the quiet periods of the earthquakes. From this study, Qs–1 and Qi–1 were shown as new parameters that can quantitatively measure the post-seismic deformation due to crustal earthquake.

Single-station seismic monitoring of permafrost on Mt. Zugspitze (Germany) over the past 15 years

<p>Permafrost thawing affects mountain slope stability and can trigger hazardous rock falls. As rising temperatures promote permafrost thawing, spatio-temporal monitoring of long-term and seasonal variations in the perennially frozen rock is therefore crucial in regions with high hazard potential. With various infrastructure in the summit area and population in the close vicinity, Mt. Zugspitze in the German/Austrian Alps is such a site and permafrost has been monitored with temperature logging in boreholes and lapse-time electrical resistivity tomography. Yet, these methods are expensive and laborious, and are limited in their spatial and/or temporal resolution.</p><p>Here, we analyze continuous seismic data from a single station deployed at an altitude of 2700 m a.s.l. in a research station, which is separated by roughly 250 m from the permafrost affected ridge of Mt. Zugspitze. Data are available since 2006 (with some gaps) and reveal high-frequency (>1 Hz) anthropogenic noise likely generated by the cable car stations at the summit. We calculate single-station cross-correlations between the different sensor components and investigate temporal coda wave changes by applying the recently introduced wavelet-based cross-spectrum method. This approach provides time series of the travel time relative to the reference stack as a function of frequency and lag time in the correlation functions. In the frequency and lag range of 1-10 Hz and 0.5-5 s respectively, we find various parts in the coda that show clear annual variations and an increasing trend in travel time over the past 15 years of consideration. Converting the travel time variations to seismic velocity variations (assuming homogeneous velocity changes affecting the whole mountain) results in seasonal velocity changes of up to a few percent and on the order of 0.1% decrease per year. Yet, estimated velocity variations do not scale linearly with lag time, which indicates that the medium changes are localized rather than uniform and that the absolute numbers need to be taken with caution. The annual velocity variations are anti-correlated with the temperature record from the summit but delayed by roughly one month.</p><p>The phasing of the annual seismic velocity change (relative to the temperature record) is in agreement with a previous study employing lapse-time electrical resistivity tomography. Furthermore, the decreasing trend in seismic velocity happens concurrently with an increasing trend in temperature. The results therefore suggest that the velocity changes are related to seasonal thaw and refreeze and permafrost degradation and thus highlight the potential of seismology for permafrost monitoring. By adding additional receivers and/or a fiber-optic cable for distributed acoustic sensing, hence increasing the spatial resolution, the presented method holds promise for lapse-time imaging of permafrost bodies with high spatio-temporal resolution from passive measurements.</p>

Seismic attenuation analysis in the central part of the Leipzig-Regensburg fault zone using the Multiple Lapse Time Window Analysis and Qopen

<p>Seismic attenuation provides valuable information about the structure of the crust. For the analysis of seismic attenuation in the central part of the Leipzig-Regensburg fault zone in Germany, where numerous areas of intracontinental earthquake swarms are located, we use 18 of the region's strongest earthquakes from the period 2008 to 2019 with a magnitude between 1.4 and 3.0 in the frequency range between 3 and 34 Hz. Two different methods were used to determine the frequency-dependent scattering and the intrinsic attenuation on one hand and to compare the two methods with respect to their results on the other hand. Both methods, the Multiple Lapse Time Windows Analysis (MLTWA) and the Qopen method use the acoustic radiative transfer theory for forward modelling to generate synthetic data and fit them to the observed data. As a by-product of Qopen, we also obtain the energy site amplifications of the stations used in the inversion, as well as the estimated moment magnitudes of the inverted earthquakes. In addition, factors that influence the inversion were investigated. Different combinations of inversion parameters were tested for the MLTWA, as well as the influence of the window length on the result of Qopen. The results from both methods provide similar results within their error bars, with intrinsic attenuation being stronger than scattering and overall, rather low attenuation values compared to other regions.</p>

Connecting velocity changes with complementary observations (fast and slow strain perturbations, temperature etc.): Insights from long-term (decades) monitoring in several Italian regions

<p>We present a set of studies on velocity variations (dv/v) measured from seismic noise correlation in the Italian region. By exploring the evolution of the dv/v as function of coda lapse time, and comparing with independent observations (e.g. dynamic and quasi-static strain, temperature induced strain, rain etc.) we are able to get new insights into the causes of velocity variations as function of space (depth). Out of our results we recognized depth dependence of coseismic velocity drop and recovery in the region of l’Aquila, and depth and spatial dependence of sensitivity to long period (years) small strain variation (~10e-6) induced by hydrological processes. In a similar way to dynamic acoustic-elastic testing in laboratory, we extract non-linear parameters of the crustal rocks. These measures are compared with laboratory results to get insights about the physical state of the rocks in the crust, in regions hosting seismogenic faults. A summary of frequency and strain dependent dv/v and sensitivity further permits to compare our results to laboratory experiments.</p>

Seismic attenuation structure across the Karakoram fault in western Tibet

SUMMARY 2-D attenuation maps are produced for the crust of western Tibet using local earthquakes which are recorded by an array of 31 broad-band stations operated from 2007 July to 2011 May. Relative contribution of scattering ($Q_{sc}^{-1}$) and intrinsic ($Q_{i}^{-1}$) attenuation have been calculated using Multiple Lapse Time Window Analysis under the assumption of uniform distribution of multiple isotropic scattering and intrinsic absorption in a medium for five different frequency bands centred at 1.5, 3, 6, 12 and 18 Hz, respectively. All the events are selected on the basis of high signal-to-noise ratio having hypocentral distance within 200 km from the respective stations. The obtained Q−1 values show a strong frequency dependent nature which can be correlated to the degree of tectonic complexity and the heterogeneities present in the medium. The intrinsic absorption is found to be the dominant mechanism at all the frequency ranges for all stations except few (WT03, WT07 and WT13) at 18 Hz, which may be correlated with the presence of partial melt, geothermal fluids, hydrothermal springs, mantle-derived fluids and radioactivity in the crust of western Tibet. We have divided the entire area into two regions across the Karakoram fault (KKF) to explore the variations of crustal attenuation properties. The first part covers the northeastern of KKF referred as Region 1 while the second part covers the southwestern of KKF referred as Region 2. The spatial variations of $Q_{i}^{-1}$ across the region exhibit significant differences between Regions 1 and 2 at all the investigated frequencies. Interestingly, Region 1 exhibits higher $Q_{i}^{-1}$ than Region 2 at lower frequencies, whereas $Q_{i}^{-1}$ shows opposite trends at higher frequencies (> 6 Hz) as it shows higher values in Region 2 than Region 1. We find that the obtained values of Q−1 are also in good agreement with the other segments of Himalaya and Tibet as well as different tectonic regions in the world.

Excitation of the global correlation wavefield by large earthquakes

SUMMARY Recorded globally, cross-correlated ground-motion time-series of the coda of large earthquakes enable the construction of a 2-D representation of correlation lapse time and inter-receiver distance—a global correlogram. A better understanding of how the features present in a correlogram are generated can revolutionize the characterization of planetary interiors. Here, we investigated correlograms based on individual large earthquakes and identified 12 events from the past decade with a multitude of prominent and some ‘exotic’ features in the first 3 hr following correlation origin. We found that the type of the source mechanism and energy-release dynamics are the key influencers responsible for individual correlograms equal in quality to a stack of hundreds of correlograms. A single event is sufficient in creating a correlogram resembling previous correlograms constructed from a large number of events, which reinforces the notion that the earthquake coda-correlation features are not ‘reconstructed’ body waves. Numerical simulations of the correlation wavefield can thus be based on exceptional-quality events, becoming more computationally affordable. Here, we explain more than 60 features of the global coda-correlogram, which presents the most extensive catalogue to date.