Source Duration Research Articles

Physical experiments of waves generated by submerged steam eruptions with applications to volcanic tsunamis.

The tsunamigenic potential of underwater volcanic eruptions is not well understood, even though eruption-generated tsunamis can be devastating. To address how erupted steam bursts from underwater volcanoes generate tsunamis, we present the experiments, using pressurized steam injected vertically into a water tank. Results over various eruption conditions identify three eruption regimes, namely, shallow-, intermediate-, and deep-water eruptions, according to the combined effects of water depths, source strengths, and source durations. The transition between shallow and intermediate eruptions is characterized by critical depths maximizing tsunami wave heights, while the transition between intermediate and deep eruptions is characterized by containment depths inhibiting surface disturbances. Water depth and source intensity are the dominant factors controlling maximum wave amplitudes, more so than aspects of jet duration and condensation. These experiments and supporting dimensional analysis improve our understanding of how underwater volcanic eruptions form tsunamis, while also providing a complete dataset for advancing tsunami generation models.

Rupture process of the 2019 Mw 6.8 Davao Del Sur earthquake, Philippines from geodetic and seismic data

Because of its complex tectonic setting, the Philippines experiences vigorous seismic activity. On December 15, 2019, an Mw 6.8 earthquake struck Davao del Sur, the Philippines, severely damaging infrastructure and adversely affecting the population. In this study, we used Interferometry Synthetic Aperture Radar (InSAR) and teleseismic broadband data to explore the earthquake’s source parameters, rupture process, and tectonic characteristics through a Bayesian modeling approach and Coulomb stress analysis. An analysis of InSAR suggested that the mainshock occurred on an NW–SE oriented single plane within the Cotabato fault system, with the Makilala-Malungon fault being the causative fault. The Joint inversion revealed that the rupture initiated in the middle crust (depth: approximately 16.5 km), exhibiting a blind, left-lateral strike-slip fault rupture propagation with minimal reverse slip and no surface rupture. The slip was concentrated in a distinct asperity spanning a depth of 3–24 km, with the peak slip reaching approximately 1.8 m. The source time function of this event indicated a single pulse with a total source duration of approximately 17 s. The static stress drop value was low, which may be related to the brittle condition of the crust. Coulomb stress changes calculations suggested earthquake risk in the future.

Scaling Relationships between Local Magnitude, Seismic Moment, and Radiated Seismic Energy for the 18 April 2019 Xiulin, Taiwan, Earthquake Sequence: Implications for Source Non-Self-Similarity

Abstract Using local seismograms, we obtain the source parameters of the 2019 ML 6.32 Xiulin, Taiwan, earthquake sequence to establish scaling relationships among the local magnitude (ML), seismic moment (M0), moment magnitude (Mw), and radiated seismic energy (ES) for ML<4.0 events. The key findings are as follows: (1) logES∝2.0ML, which is consistent with previous studies; (2) logM0∝1.0ML, which leads to Mw∝0.67ML; and (3) the scaled energy (ES/M0) is proportional to M0. These relationships imply that the source duration (T) should be independent of M0. Further analysis via forward waveform modeling reveals a very weak correlation between T and M0 (i.e., logT∝0.03logM0), suggesting that T should be nearly constant. These findings indicate that the source properties of the 2019 Xiulin earthquake sequence were not self-similar. In addition, the two relationships, logES∝2.0ML and logM0∝1.0ML, suggest that ES/M0 should increase with M0 rather than ES/M0 tending to be a constant.

A Detailed Understanding of Slow Self‐Arresting Rupture

AbstractRecent numerical simulation studies suggest the existence of a seismic type that is distinct from regular earthquakes—the slow self‐arresting rupture (SSAR). Unlike regular earthquakes that propagate dynamically following the initiation, The SSARs automatically arrest within the nucleation zone without interference. Additionally, numerical simulations indicate that SSARs exhibit a significantly lower energy release compared to regular earthquakes, while also exhibiting a relatively long source duration. Given these distinctive properties, comprehending the source processes of SSARs assumes great strategic importance. However, our current understanding of SSARs, particularly regarding their response to different frictional conditions and their correlation with natural phenomena, remains limited in scope. To further explore the intricacies of SSARs, we employ a three‐dimensional fully dynamic source model to simulate SSARs under various slip‐weakening frictional conditions. The findings indicate that SSARs occur in frictional environments characterized by large normalized critical slip distances, with the seismic source process being primarily influenced by this parameter. Apart from displaying significantly smaller average slip and stress drop, which are two to three orders of magnitude lower than those of regular earthquakes of comparable magnitude, SSARs also showcase a decrease in duration, seismic moment, slip rate, and stress drop as the normalized critical slip distance increases. The moment‐duration scaling law of SSARs exhibits a linear pattern. Moreover, the observation of slow earthquakes offers further implications for the presence of SSARs, indicating their potential association with a wider range of intricate seismic phenomena.

Combined Electrochemical Deposition and Photo-Reduction to Fabricate SERS-Active Silver Substrates: Characterization and Application for Malachite Green Detection in Aquaculture Water.

This research introduces a novel approach using silver (Ag) nanostructures generated through electrochemical deposition and photo-reduction of Ag on fluorine-doped tin oxide glass substrates (denoted as X-Ag-AgyFTO, where 'X' and 'y' represent the type of light source and number of deposited cycles, respectively) for surface-enhanced Raman spectroscopy (SERS). This study used malachite green (MG) as a Raman probe to evaluate the enhancement factors (EFs) in SERS-active substrates under varied fabrication conditions. For the substrates produced via electrochemical deposition, we determined a Raman EF of 6.15 × 104 for the Ag2FTO substrate. In photo-reduction, the impact of reductant concentration, light source, and light exposure duration were examined on X-Ag nanoparticle formation to achieve superior Raman EFs. Under optimal conditions (9.0 mM sodium citrate, 460 nm blue-LED at 10 W for 90 min), the combination of blue-LED-reduced Ag (B-Ag) and an Ag2FTO substrate (denoted as B-Ag-Ag2FTO) exhibited the best Raman EF of 2.79 × 105. This substrate enabled MG detection within a linear range of 0.1 to 1.0 µM (R2 = 0.98) and a detection limit of 0.02 µM. Additionally, the spiked recoveries in aquaculture water samples were between 90.0% and 110.0%, with relative standard deviations between 3.9% and 6.3%, indicating the substrate's potential for fungicide detection in aquaculture.

Co‐Occurrence of Low and Very Low Frequency Earthquakes Explained From Dynamic Modeling

AbstractVery low‐frequency earthquakes (VLFs) are characterized by longer source duration and smaller stress drop than regular earthquakes of similar magnitude. Recent studies have shown their frequent correlation with low‐frequency earthquakes (LFEs) on shared faults. The underlying source processes governing the occurrence of VLFs and their interaction with LFEs remain elusive. Here, we employ a slip‐weakening model for slow earthquakes. By comparing the source parameters of simulations and observations, it is suggested that VLFs are slow self‐arresting earthquakes that self‐terminate within the nucleation patch. Additionally, we adopt a composite model to reproduce the records of the simultaneous occurrences of a VLF and an LFE in the Nankai area. Our results present the possibility that VLFs, LFEs, and regular earthquakes can be distinguished using a unified dynamic framework.

254 Effect of feeding high oleic soybean oil to finishing pigs on growth performance, carcass characteristics, and meat quality

Abstract The objective of this study was to evaluate the effects of dietary fat source and feeding duration on growth performance, carcass characteristics, and meat quality of finishing pigs. Finishing pigs [n = 450; 21 wk of age; initial body weight (BW) = 113.7 ± 8 kg] were housed in 90 pens and assigned to one of five dietary treatments in a 2 × 2 + 1 factorial design. Dietary treatments consisted of two fat sources (CWG: 4% inclusion of choice white grease and HOSO: 4% inclusion of high oleic soybean oil) each provided 2 or 4 wk before marketing. The “+1” diet was a corn-based diet without fat inclusion (CON). Observations included pig growth performance (on d 14 and d 28 of feeding), carcass characteristics (12 pigs per treatment at marketing), fatty acid profile in the loins and bellies, and a consumer sensory evaluation. Data were analyzed using PROC MIXED in SAS considering dietary treatment as a main effect, feeding duration, and their interactions. Contrast tests were used to compare dietary treatments with control group. From d 14 to 28 and overall experimental period (d 0–28), pigs fed fat-supplemented diets had a greater (P < 0.05) average daily gain and gain to feed ratio than CON fed pigs. There was no significant difference (P > 0.05) in growth performance when comparing fat sources or feeding periods. Pigs supplemented with either CWG or HOSO showed a tendency to have a greater (P < 0.1) belly weight and belly yield, and a lesser (P < 0.1) loin yield and loin muscle area when compared with CON pigs. Loins from the 2-wk period of fat supplementation had darker (Coloration l, P < 0.05) meat coloration when compared with 4 wk. The loin from pigs fed fat sources had greater (P < 0.05) concentration of oleic acid and eicosenoic acid when compared with CON. This improvement was mainly from HOSO. When CWG was compared with HOSO, pigs fed CWG had a greater (P < 0.05) concentration of palmitic acid and stearic acid while the HOSO pigs had a greater concentration of oleic acid and linolenic acid in the loin. In the belly, CON had greater (P < 0.05) concentration of palmitic acid and stearic acid while pigs fed fat sources had a greater concentration of oleic acid and eicosenoic acid. Bellies from HOSO had greater (P < 0.05) concentration of oleic acid and α-linolenic acid methyl ester while CWG had greater concentration of g-linolenic acid. As for the sensory evaluation, the palatability and acceptability of pork were not affected (P > 0.05) by dietary treatments. In conclusion, supplementation with HOSO not only improved performance but tended to improve some carcass characteristics and increased the concentration of oleic acid and some other unsaturated FAs with a concomitant decrease in the concentration of some saturated FAs in pork.

The 2020 Mw 7.0 Samos (Eastern Aegean Sea) Earthquake: joint source inversion of multitype data, and tsunami modelling

SUMMARY We present a kinematic slip model and a simulation of the ensuing tsunami for the 2020 Mw 7.0 Néon Karlovásion (Samos, Eastern Aegean Sea) earthquake, generated from a joint inversion of high-rate GNSS, strong ground motion and InSAR data. From the inversion, we find that the source time function has a total duration of ∼20 s with three peaks at ∼4, 7.5 and 15 s corresponding to the development of three asperities. Most of the slip occurs at the west of the hypocentre and ends at the northwest downdip edge. The peak slip is ∼3.3 m, and the inverted rake angles indicate predominantly normal faulting motion. Compared with previous studies, these slip patterns have essentially similar asperity location, rupture dimension and anticorrelation with aftershocks. Consistent with our study, most published papers show the source duration of ∼20 s with three episodes of increased moment releases. For the ensuing tsunami, the eight available gauge records indicate that the tsunami waves last ∼18–30 hr depending on location, and the response period of tsunami is ∼10–35 min. The initial waves in the observed records and synthetic simulations show good agreement, which indirectly validates the performance of the inverted slip model. However, the synthetic waveforms struggle to generate long-duration tsunami behaviour in simulations. Our tests suggest that the resolution of the bathymetry may be a potential factor affecting the simulated tsunami duration and amplitude. It should be noted that the maximum wave height in the records may occur after the decay of synthetic wave amplitudes. This implies that the inability to model long-duration tsunamis could result in underestimation in future tsunami hazard assessments.

Sensitivity of the second seismic moments resolution to determine the fault parameters of moderate earthquakes

Second-degree seismic moments provide a simple description of the spatiotemporal extent of the earthquake source. Finite source attributes such as rupture length, width, duration, velocity, and propagation direction can be estimated by computing second-degree seismic moments without the need for a predefined rupture model. This is achieved by analyzing the properties of apparent source time functions (ASTFs) obtained from seismic signals recorded at different stations after eliminating instrument responses and path effects. In this study, to define the limits of its application in the analysis of small earthquakes and to evaluate the sensitivity and reliability of the results to uncertainties due to observations and prior knowledge, we modeled a synthetic seismic source and examined how potential uncertainties in hypocentral depth, velocity model, focal mechanism, source duration, and number of recording stations can affect the inversion results. An accurate ASTF is essential to obtain robust results and our findings show that the mean values of the key source parameters, i.e., fracture size, source duration, and rupture velocity, are generally well reproduced in all sensitivity tests, with some exceptions, within the standard deviation. We also demonstrate that large uncertainties in the hypocentral depth and inaccurate velocity models introduce a significant bias, especially in rupture size and average centroid velocity, indicating the strong influence of ray path calculation in the inversion process. These resolution limits must therefore be taken into account when interpreting the results obtained with this technique.

X-Ray Energy Deposition Model for Simulating Asteroid Response to a Nuclear Planetary Defense Mitigation Mission

In the event of a potentially catastrophic asteroid impact, with sufficient warning time, deploying a nuclear device remains a powerful option for planetary defense if a kinetic impactor or other means of deflection proves insufficient. Predicting the effectiveness of a potential nuclear deflection or disruption mission depends on accurate multiphysics simulations of the device's X-ray energy deposition into the asteroid and the resulting material ablation. The relevant physics in these simulations span many orders of magnitude, require a variety of different complex physics packages, and are computationally expensive. Having an efficient and accurate way of modeling this system is necessary for exploring a mission's sensitivity to the asteroid's range of physical properties. To expedite future simulations, we present a completed X-ray energy deposition model developed using the radiation-hydrodynamics code Kull that can be used to initiate a nuclear mitigation mission calculation. The model spans a wide variety of possible mission initial conditions: four different asteroid-like materials at a range of porosities, two different source spectra, and a broad range of radiation fluences, source durations, and angles of incidence. Using blowoff momentum as the primary metric, the model-initiated simulation results match the full radiation-hydrodynamics results to within 10%.

GNSS-Constrained Rupture Kinematics of the 2022 Mw 6.7 Luding, China, Earthquake: Directivity Pulse during the Asymmetrical Bilateral Rupture

Abstract Impulse motion characterized by a large amplitude in the fault-normal direction can be observed at near-fault strong motion sites during strike-slip earthquakes. The large pulse, which always causes high intensity and stronger damage to structures close to faults, is usually attributed to the directivity effect of rupture propagating along strike and the proximity to the fault. We present an analysis of such a large directivity pulse captured by the near-fault high-rate Global Navigation Satellite System (GNSS) during the 2022 Mw 6.7 Luding, China, earthquake—the largest event ever observed by space geodesy on the seismically active Xianshuihe fault in the eastern Tibetan Plateau. We invert the displacement waveforms and offsets derived from the continuous and campaign GNSS for the rupture kinematics. The inferred slip model reveals a rupture zone of 30 km in length above 15 km depth along the Moxi segment, yielding a seismic moment of 1.1×1019 N·m and a source duration of 13 s. The high-rate GNSS (hrGNSS) waveforms suggest an asymmetric bilateral rupture: most slips with long rise time are concentrated on the southern part of the ruptured fault, whereas a short-duration pulse-like slip rate with low final slip propagates during the northward rupture. We found that the directivity pulse observed by the nearest hrGNSS site is controlled primarily by the sharp pulse-like slip rate and rapid rupture velocity approximating the local S-wave velocity. Along with additional local amplification, this large directivity pulse may be responsible for the heavy damage in Moxi town close to the northern ruptured fault.

Auction market placement and a rest stop during transportation affect the respiratory bacterial microbiota of beef cattle.

Bovine respiratory disease (BRD) is a significant health problem in beef cattle production, resulting in considerable economic losses due to mortalities, cost of treatment, and reduced feed efficiency. The onset of BRD is multifactorial, with numerous stressors being implicated, including transportation from farms to feedlots. In relation to animal welfare, regulations or practices may require mandatory rest times during transportation. Despite this, there is limited information on how transportation and rest stops affect the respiratory microbiota. This study evaluated the effect of cattle source (ranch-direct or auction market-derived) and rest stop duration (0 or 8 h of rest) on the upper respiratory tract microbiota and its relationship to stress response indicators (blood cortisol and haptoglobin) of recently weaned cattle transported for 36 h. The community structure of bacteria was altered by feedlot placement. When cattle were off-loaded for a rest, several key bacterial genera associated with BRD (Mannheimia, Histophilus, Pasteurella) were increased for most sampling times after feedlot placement for the ranch-direct cattle group, compared to animals given no rest stop. Similarly, more sampling time points had elevated levels of BRD-associated genera when auction market cattle were compared to ranch-direct. When evaluated across time and treatments several genera including Mannheimia, Moraxella, Streptococcus and Corynebacterium were positively correlated with blood cortisol concentrations. This is the first study to assess the effect of rest during transportation and cattle source on the respiratory microbiota in weaned beef calves. The results suggest that rest stops and auction market placement may be risk factors for BRD, based solely on increased abundance of BRD-associated genera in the upper respiratory tract. However, it was not possible to link these microbiota to disease outcome, due to low incidence of BRD in the study populations. Larger scale studies are needed to further define how transportation variables impact cattle health.

Automatic determination of focal depth with the optimal period of Rayleigh wave amplitude spectra at local distances

SUMMARY Focal depth of earthquakes is essential for studies of seismogenic processes and seismic hazards. In regions with dense seismic networks, focal depth can be resolved precisely based on the traveltime of P and S, which is less feasible in case of sparse networks. Instead, surface waves are usually the strongest seismic phases at local and regional distances, and its excitation is sensitive to source depth, thus theoretically important for estimating focal depth even with a limited number of seismic stations. In this study, short-period (0.5–20 s) Rayleigh waves are explored to constrain focal depths. We observe that the optimal period (the period corresponding to the maximum amplitude) of Rayleigh waves at local distances (≤200 km) shows an almost linear correlation with focal depth. Based on this finding, we propose an automated method for resolving the focal depth of local earthquakes using the linear regression relation between the optimal period of Rayleigh wave amplitude spectra and focal depth. Synthetic tests indicate the robustness of this method against source parameters (focal mechanism, source duration and non-double-couple component) and crustal velocity structure. Although the attenuation (Q factor) of shallow crust can introduce complexities in determining focal depth, it can be simultaneously estimated if a sufficient number of stations are available. The proposed method is applied to tens of small-to-moderate earthquakes (Mw 3.5–5.0) in diverse tectonic settings, including locations in the United States (Oklahoma, South Carolina, California, Utah, etc.) and China (Sichuan, Shandong). Results demonstrate that reliable focal depth, with uncertainty of 1–2 km, can be determined even with one or a few seismic stations. This highlights the applicability of the method in scenarios characterized by sparse network coverage or historical events.

Acoustic Emission as a Method for Analyzing Changes and Detecting Damage in Composite Materials During Loading

Thanks to their excellent strength and durability, composite materials are used to manufacture many important structural elements. In the face of their extensive use, it is crucial to seek suitable methods for monitoring damages and locating their origins. The purpose of the article was to verify the possibility of applying the acoustic emissions (AE) method in the detection of damages in the structures of composite materials. The experimental part comprised static tensile tests carried out on various sandwich composites, including simultaneous registration of elastic waves with increasing loads, carried out with the use of an acousticelectrical sensor connected. The signal obtained from the sensor was then further processed and used to draw up diagrams of the AE hits, amplitude, root mean square of the AE source signal (RMS) and duration in the function of time. These diagrams were then applied on their corresponding stretching curves, the obtained charts were analysed. The results obtained point to a conclusion that the acoustic emissions method can be successfully used to detect and locate composite material damages.

1401-P: Psychotropic Drug Use in Children and Adolescents with Type 1 Diabetes

Psychiatric disorders in children and adolescents with type 1 diabetes (T1D) have caught increasing attention. While psychotropic drugs offer great value in managing psychiatric symptoms, their adverse effects engender considerable controversy regarding their use in pediatric patients, let alone in those with T1D. Despite the topic’s high visibility, little evidence exists on the patterns of psychotropic drug use in pediatric T1D patients. We thus conducted this cohort study of 3,720,381 children and adolescents (13,191 [0.36%] had T1D) using several Swedish national registers. We examined the trends and patterns (prescription source and treatment duration) of psychotropic drug use and estimated the risk of initiating psychotropic drugs after T1D onset. We found that psychotropic drug use increased significantly in children and adolescents with T1D from 2006 to 2019 (Figure 1), with ADHD medications, SSRI, hypnotics and anxiolytics among the most used ones. The primary prescription source was psychiatric care, and treatment durations were mostly <12 months (except for ADHD medications). Children and adolescents with newly-onset T1D had a higher risk of initiating any psychotropic drug (hazard ratio 1.29, 95%CI 1.20-1.38) than their peers without T1D. Our findings highlight the need for risk/benefit studies of psychotropic drugs among young users with T1D to inform future research and guideline development. Disclosure S.Liu: None. T.Lagerberg: None. J.F.Ludvigsson: Research Support; Janssen Pharmaceuticals, Inc., MSD Life Science Foundation. M.Taylor: None. B.Donofrio: None. P.Lichtenstein: None. S.Gudbjörnsdottir: None. A.Butwicka: None. Funding Swedish Research Council (2017-00788)

Validation of the Osaka basin velocity model by waveform simulation using sources inverted with reciprocal Green’s functions

To advance the methodology for validating velocity models by waveform comparison, we estimated source parameters for small magnitude earthquakes that can be approximated by point sources. Instead of using published source models, we used the reciprocity method to calculate 3D Green’s functions using the target velocity structure itself, and then inverted the earthquake sources. This method greatly reduces the calculations required compared to a full inversion of the source mechanism, depth, and source duration (risetime), making it possible to reproduce input ground motions in the target basin. Here, we validated the Japan Integrated Velocity Structure model of the Osaka basin using five earthquakes around the Osaka basin; these earthquakes allowed us to investigate the impact of the incident waves’ propagation directions. We first estimated source parameters using records at control bedrock sites surrounding the Osaka basin to reproduce the input ground motions. Then, we conducted a 3D finite-difference simulation for sites within the basin. By mapping the distributions of misfit values for individual waveforms, peak ground velocities, and response spectra, we were able to identify areas in the basin that require additional tuning of the velocity model.Graphical

The frequency ratio and time delay of solar radio emissions with fundamental and harmonic components

ABSTRACT Solar radio bursts generated through the plasma emission mechanism produce radiation near the local plasma frequency (fundamental emission) and double the plasma frequency (harmonic). While the theoretical ratio of these two frequencies is close to 2, simultaneous observations give ratios ranging from 1.6 to 2, suggesting either a ratio different from 2, a delay of the fundamental emission, or both. To address this long-standing question, we conducted high-frequency, high-time resolution imaging spectroscopy of type III and type J bursts with fine structures for both the fundamental and harmonic components with LOFAR between 30 and 80 MHz. The short-lived and narrow frequency-band fine structures observed simultaneously at fundamental and harmonic frequencies give a frequency ratio of 1.66 and 1.73, similar to previous observations. However, frequency-time cross-correlations suggest a frequency ratio of 1.99 and 1.95 with a time delay between the F and H emissions of 1.00 and 1.67 s, respectively for each event. Hence, simultaneous frequency ratio measurements different from 2 are caused by the delay of the fundamental emission. Among the processes causing fundamental emission delays, anisotropic radio-wave scattering is dominant. Moreover, the levels of anisotropy and density fluctuations reproducing the delay of fundamental emissions are consistent with those required to simulate the source size and duration of fundamental emissions. Using these simulations we are able to, for the first time, provide quantitative estimates of the delay time of the fundamental emissions caused by radio-wave propagation effects at multiple frequencies, which can be used in future studies.

Source process of two Mw 6.9 aftershocks of the 2015 Mw 8.3 Illapel earthquake

The rupture of the September 16, 2015, Mw 8.3 Illapel earthquake extended over 200 km length along strike, where the southern portion of the rupture area is controlled tectonically by the collision of the Juan Fernandez Ridge at ∼32.5°S. On November 11th, two large aftershocks occurred in less than an hour, at shallow depths and epicenters closely located. Both events occurred beyond, but nearby, the northern limit of the Illapel rupture. We inverted kinematic rupture models by joint inversion of strong-motion and teleseismic body waves datasets. The Akaike's Bayesian Information Criterion (ABIC) was used to estimate the relative weighting between datasets, as well as the weighting of spatial and temporal constraints. The rupture of the first event propagated updip from the hypocenter, and later in a bilateral mode, with large slip to the south. The slip solution yields a total seismic moment of 4.44 × 1019 N m (Mw 7.0), and peak-slip of 0.82 m. The epicenter of the second event relocates 15 km southwest with respect to the first one. The rupture of the second event propagated mainly southwards and updip to the trench, re-rupturing an area already broken by the first event. The estimated seismic moment is 3.11 × 1019 N m (Mw 6.9), with a maximum slip of 0.59 m. The source durations from their respective moment-rate functions are 35 s, in both models. The spatial slip distribution retrieved for the two events suggests that the upper portion of the megathrust slipped, a region that is usually thought to behave aseismically, controlled by velocity-strengthening friction. We also relocated the earthquake catalog using a double-difference algorithm. The spatial distribution of seismicity shows clusters that are analyzed in different groups, and the most remarkable feature being a strip running parallel - and close by - to the trench region with very low seismicity. The majority of regional moment tensor solutions are thrust faulting mechanisms, and given the centroid depths retrieved, these events are consistent with interplate seismicity.

Effect of credit services and socioeconomic factors on the income of cocoa marketers in Ondo State, Nigeria

Cocoa has remained a valuable crop and major foreign exchange earner among other agricultural commodity export of the Nigerian economy. Therefore, the study evaluates the effect of credit services and socioeconomic factors on the income of cocoa marketers in Ondo State, Nigeria. Primary data were used with the aid of a well-structured questionnaire. A multistage sampling technique was used to select 120 cocoa marketers. Descriptive statistics, budgetary technique and Ordinary Least Squares (OLS) were used for the analysis. The costs and returns analysis reveal that the net marketing income for the average cocoa marketer was ₦8,560,344 per annum while the total revenue of an average cocoa marketer was ₦20,716,187 per annum. The marketing efficiency ratio is 70.4 while the return on investment (ROI) is estimated to be 1.7. That is out of every ₦1 invested, the average marketer made a profit of ₦1 and 7 kobo. The results of OLS revealed that transportation, credit size, credit source, and credit duration were the main determinants marketers’ income in the area. Lack of collaterals and poor financial management skills are the main constraints faced by the marketers. Thus, it is recommended that credit should be provided for cocoa marketers with moderate collateral requirement and interest rate in order to give each and every cocoa marketer the chance to expand their scale of operations.

Synthesis of CuO and PAA-Regulated Silver-Carried CuO Nanosheet Composites and Their Antibacterial Properties.

With the aid of a facile and green aqueous solution approach, a variety of copper oxide (CuO) with different shapes and polyacrylic-acid (PAA)-regulated silver-carried CuO (CuO@Ag) nanosheet composites have been successfully produced. The point of this article was to propose a common synergy using Ag-carried CuO nanosheet composites for their potential antibacterial efficiency against three types of bacteria such as E. coli, P. aeruginosa, and S. aureus. By using various technical means such as XRD, SEM, and TEM, the morphology and composition of CuO and CuO@Ag were characterized. It was shown that both CuO and CuO@Ag have a laminar structure and exhibit good crystallization, and that the copper source and reaction duration have a sizable impact on the morphology and size distribution of the product. In the process of synthesizing CuO@Ag, the appropriate amount of polyacrylic acid (PAA) can inhibit the agglomeration of Ag NPs and regulate the size of Ag at about ten nanometers. In addition, broth dilution, optical density (OD 600), and electron microscopy analysis were used to assess the antimicrobial activity of CuO@Ag against the above three types of bacteria. CuO@Ag exhibits excellent synergistic and antibacterial action, particularly against S. aureus. The antimicrobial mechanism of the CuO@Ag nanosheet composites can be attributed to the destruction of the bacterial cell membrane and the consequent leakage of the cytoplasm by the release of Ag+ and Cu2+. The breakdown of the bacterial cell membrane and subsequent leakage of cytoplasm caused by Ag+ and Cu2+ released from antimicrobial agents may be the cause of the CuO@Ag nanosheet composites' antibacterial action. This study shows that CuO@Ag nanosheet composites have good antibacterial properties, which also provides the basis and ideas for the application research of other silver nanocomposites.