Previous Deployment Research Articles

Spatiotemporal Evolution of Slow Slip Events at the Offshore Hikurangi Subduction Zone in 2019 Using GNSS, InSAR, and Seafloor Geodetic Data

AbstractDetecting crustal deformation during transient deformation events at offshore subduction zones remains challenging. The spatiotemporal evolution of slow slip events (SSEs) on the offshore Hikurangi subduction zone, New Zealand, during February–July 2019, is revealed through a time‐dependent inversion of onshore and offshore geodetic data that also accounts for spatially varying elastic crustal properties. Our model is constrained by seafloor pressure time series (as a proxy for vertical seafloor deformation), onshore continuous Global Navigation Satellite System (GNSS) data, and Interferometric Synthetic Aperture Radar displacements. Large GNSS displacements onshore and uplift of the seafloor (10–33 mm) require peak slip during the event of 150 to >200 mm at 6–12 km depth offshore Hawkes Bay and Gisborne, comparable to maximum slip observed during previous seafloor pressure deployments at north Hikurangi. The onshore and offshore data reveal a complex evolution of the SSE, over a period of months. Seafloor pressure data indicates the slow slip may have persisted longer near the trench than suggested by onshore GNSS stations in both the Gisborne and Hawkes Bay regions. Seafloor pressure data also reveal up‐dip migration of SSE slip beneath Hawke Bay occurred over a period of a few weeks. The SSE source region appears to coincide with locations of the March 1947 Mw 7.0–7.1 tsunami earthquake offshore Gisborne and estimated great earthquake rupture sources from paleoseismic investigations offshore Hawkes Bay, suggesting that the shallow megathrust at north and central Hikurangi is capable of both seismic and aseismic rupture.

Transfemoral leadless pacemaker implantation after tricuspid valve surgery and intervention

Abstract Background and Purpose Pacemaker (PM) implantation after surgical or transcatheter tricuspid valve (TV) repair or replacement may be challenging. Transcatheter leadless pacemaker (LPM) implantation has become a routine procedure and is frequently adopted in patients without the need for an atrial lead, in cases with cardiac implantable device infection or in patients with marked comorbidities. The use of LPM in patients with previous TV repair or replacement has only been described in singular cases in literature. We present our single center experience of LPM implantation after TV repair. Methods Patients with a history of TV repair or replacement who underwent LPM in our institution between 01/2020 and 11/2023 were retrospectively analyzed. All patients underwent routine clinical follow-up investigations including LPM interrogation and transthoracic echocardiography to assess for TV status. For LPM implantation right anterior oblique (RAO) and left anterior oblique (LAO) caudal fluoroscopy projections were utilized to enable LPM device passage across the TV. Results The study population consisted of 10 patients (9 females, mean age 74.0±10.0 years). Two patients had a history of surgical TV annuloplasty repair and two patients a history of surgical valve replacement, four patients of transcatheter TV repair (one through the mitral clip), one patient of transcatheter valve-in-ring bio prosthesis implantation prosthesis after previous surgical ring deployment and one patient transcatheter TV replacement (Figure1). All patients suffered from permanent atrial fibrillation previous to implantation procedures. Three patients were on chronic hemodialysis therapy before LPM implantation. LPM systems were successfully implanted in all cases with a mean procedure time of 43.5±26.5 minutes and a mean fluoroscopy time of 5.9±5.5 minutes and a radiation dose of 1148,7±1424,9 cGy·cm2. For fluoroscopically guided TV crossing a mean LAO angle of 43.6±14.1° (range 22 to 53°) and caudal angle of 8.5±6.9° (range 0 to 20°) was utilized (Figure 2). The LPM device was positioned in the first positioning attempt in a right ventricular high septal localization in 8 cases. Mean pacing threshold was 0.36±0.07 V at 0.25 ms, with a mean sensing amplitude of 10.5±2.9 mV and a mean of 853±324 Ohms pacing impedance. No periprocedural complications occurred. Mean duration of follow-up was 8.1±9.2 months. There were no newly developed TV regurgitations noted. Pacing thresholds (0.37±0.1 V/0.25 ms), sensing amplitude (11.8±4.5 mV) as well as pacing impedances (865±365 Ohms) remained stable until the last follow-up investigation. Conclusion LPM implantation was feasible in patients with a history of TV repair or replacement. LPM implantation was safe and effective in various modalities of TV repair. LPM may be an alternative to conventional pacemaker implantations as well as surgical lead placement in selected patients.Figure 1.Figure 2.

Impact of Rank, Provider Specialty, and Unit Sustainment Training Frequency on Military Critical Care Air Transport Team Readiness.

The Critical Care Air Transport (CCAT) Advanced Course utilizes fully immersive high-fidelity simulations to assess personnel readiness for deployment. This study aims to determine whether simple well-defined demographic identifiers can be used to predict CCAT students' performance at CCAT Advanced. CCAT Advanced student survey data and course status (pass/fail) between March 2006 and April 2020 were analyzed. The data included students' Air Force Specialty Code (AFSC), military status (active duty and reserve/guard), CCAT deployment experience (yes/no), prior CCAT Advanced training (yes/no), medical specialty, rank, and unit sustainment training frequency (never, frequency less often than monthly, and frequency at least monthly). Following descriptive analysis and comparative tests, multivariable regression was used to identify the predictors of passing the CCAT Advanced course for each provider type. A total of 2,576 student surveys were analyzed: 694 (27%) physicians (MDs), 1,051 (40%) registered nurses (RNs), and 842 (33%) respiratory therapists (RTs). The overall passing rates were 92.2%, 90.3%, and 85.4% for the MDs, RNs, and RTs, respectively. The students were composed of 579 (22.5%) reserve/guard personnel, 636 (24.7%) with CCAT deployment experience, and 616 (23.9%) with prior CCAT Advanced training. Regression analysis identified groups with lower odds of passing; these included (1) RNs who promoted from Captain to Major (post-hoc analysis, P = .03), (2) RTs with rank Senior Airman, as compared to Master Sergeants (post-hoc analysis, P = .04), and (3) MDs with a nontraditional AFSC (P = .0004). Predictors of passing included MDs and RNs with CCAT deployment experience, odds ratio 2.97 (P = .02) and 2.65 (P = .002), respectively; and RTs who engaged in unit CCAT sustainment at least monthly (P = .02). The identifiers prior CCAT Advanced training or reserve/guard military status did not confer a passing advantage. Our main result is that simple readily available metrics available to unit commanders can identify those members at risk for poor performance at CCAT Advanced readiness training; these include RNs with rank Major or above, RTs with rank Senior Airman, and RTs who engage in unit sustainment training less often than monthly. Finally, MD specialties which are nontraditional for CCAT have significantly lower CCAT Advanced passing rates, reserve/guard students did not outperform active duty students, there was no difference in the performance between different RN specialties, and for MD and RN students' previous deployment experience was a strong predictor of passing.

FedMon: A Federated Learning Monitoring Toolkit

Federated learning (FL) is rapidly shaping into a key enabler for large-scale Artificial Intelligence (AI) where models are trained in a distributed fashion by several clients without sharing local and possibly sensitive data. For edge computing, sharing the computational load across multiple clients is ideal, especially when the underlying IoT and edge nodes encompass limited resource capacity. Despite its wide applicability, monitoring FL deployments comes with significant challenges. AI practitioners are required to invest a vast amount of time (and labor) in manually configuring state-of-the-art monitoring tools. This entails addressing the unique characteristics of the FL training process, including the extraction of FL-specific and system-level metrics, aligning metrics to training rounds, pinpointing performance inefficiencies, and comparing current to previous deployments. This work introduces FedMon, a toolkit designed to ease the burden of monitoring FL deployments by seamlessly integrating the probing interface with the FL deployment, automating the metric extraction, providing a rich set of system, dataset, model, and experiment-level metrics, and providing the analytic means to assess trade-offs and compare different model and training configurations.

Discussion of infrasonic detection of tornadoes in the Southeastern United States

It has been established that tornadoes emit an infrasonic signal that is regularly detected in the 1 to 10 Hz band, although the actual band is expected to be wider. The physical mechanism through which this signal is generated is not yet fully understood and is the subject of current research. Here we discuss some of our experimental efforts, past and present. During the tornado seasons of 2017, 2018, and 2019, we deployed a network of infrasound sensor arrays in northern Alabama, southern Tennessee, and northwestern Georgia. We performed detailed analysis of one particular storm front that spawned at least eight identified tornadoes in northwestern Alabama during its passage. For that storm we find that when propagation modeling and wind noise analyses suggest that the signal should have been detected at a given array it always was. A long term monitoring effort is now underway in Mississippi. The Mississippi network deployment strategy relied on statistical analyses of tornado touchdown probability, signal transmission loss, and local wind noise studies. The network and array design for our Mississippi network was heavily informed by our experiences in Alabama and, we believe, represents the current state-of-the-art. In this presentation we will give an overview of what was learned from our previous deployments in Alabama, what strategies were used for the current deployment in Mississippi, and the current state of our data collection and analysis.

Disparities in Demographics in Hip Arthroplasty Between U.S. Active Duty Military and the ACS-NSQIP Clinical Registry.

Patient demographics, such as sex and age, are known risk factors for undergoing revision following primary total hip arthroplasty (THA). The military population is unique because of the increased rates of primary and secondary osteoarthritis of the hip. Treatment options are limited for returning patients to their line of duty; however, THA has been shown to be an effective option. The primary purpose of this study was to evaluate and contrast the demographic differences of patients undergoing primary THA between the U.S. active duty military population and the general population. The secondary goal was to identify the proportion of primary THA performed at the MTF within the military health system (MHS). This was an exempt study determined by the local institutional review board. A retrospective analysis of the MHS Data Repository (MDR) and the National Surgical Quality Improvement Program (NSQIP) was performed. The databases were used to identify the patients who underwent THA from January 1, 2015 to December 31, 2020. The MDR was used to identify demographics such as sex, age, setting of surgery, geographic location, previous military deployments, history of deployment-related injuries, branch of service, and rank. The NSQIP database was queried for sex and age. The median age of the population was compared using the Mann-Whitney U test and gender was compared using the Chi-square test. The MDR was used to evaluate 2,734 patients, whereas the NSQIP database was used to evaluate 223,832 patients. In the military population, patients who underwent THA were 87.7% male with an average age of 45 years, whereas in the general population as measured via the NSQIP database, 45.2% patients were male with an average age of 66.0 years. Comparing the two groups, we demonstrated that the military patients were significantly more likely to be younger (P < .001) and males (P < .001). Only 29.6% of primary THAs were performed within the MTF. Patients in the MHS are undergoing THA at a younger age and are more likely to be male compared to the general population. A significant portion of primary THAs in the MHS are also being performed at civilian institutions. These demographics may result in increased risk of revision; however, long-term studies are warranted to evaluate survivorship in this unique population.

Death by remote control: Drone warfare in Afghanistan, Ukraine and beyond

This article examines the use of military drones over the past 20 years. It includes the following: (1) a critical review of how drone warfare in the US‐led ‘war on terror’ affected drone crews and those ‘living under drones’; (2) an analysis of how drone warfare in Ukraine and Russia differs from previous deployments of the technology; and (3) a careful assessment of what lies ahead, as national governments and technology firms race to develop AI‐enabled drones and autonomous weapons systems on a broad scale.

Impact of life-threatening military incidents during deployments abroad on the relationships between military personnel and their families.

The influence of deployments on family relationships has hardly been investigated. Following a recently proposed new research strategy, military personnel with and without deployment-related life-threatening military incidents during deployment were compared. The hypothesis was that partner and family relationships of military personnel who experienced such an event would deteriorate more. This study included N = 255 military personnel who had a romantic partner (n = 78 of them had children) when deployed to Afghanistan. Of these, n = 68 military personnel experienced a deployment-related critical event during the deployment, n = 187 did not. Partnership quality was assessed using a semi-structured pre- and post-deployment interview. The partner relationships of military personnel who experienced a deployment-related life-threatening military incident during deployment broke up significantly more often. The partner relationships of all military personnel deteriorated significantly, with greater deterioration after deployment in the group who faced such incidents. These results were independent of age, rank or number of previous deployments. In addition, there was a significant deterioration in the relationships between all military personnel and their children with greater deterioration after deployment in the group who faced such incidents. Life-threatening military incidents during a deployment abroad appear to have a considerable influence on the quality and stability of the partner and family relationships of military personnel. These findings can be used to inform the development of specific pre- and post-deployment measures and training.

Cost of Implementing mHealth in Community Mental Health Settings: External Versus Internal Facilitation.

This study aimed to compare the costs of two implementation models for the mobile health (mHealth) intervention FOCUS in community mental health settings. The external facilitation (EF) approach uses a hub-and-spoke model, in which a central specialist provides support to clinicians and clients at multiple agencies. With the internal facilitation (IF) approach, frontline clinical staff at each center are trained to serve as their organization's local specialists. Financial and economic cost data were collected in the context of a hybrid type 3 effectiveness-implementation trial by using a mixed-methods, top-down expenditure analysis with microcosting approaches. The analysis compared the incremental costs of both models and the costs of successfully engaging clients (N=210) at 20 centers. Costs were characterized as start-up or recurrent (personnel, supplies, contracted services, and indirect costs). The average annual financial cost per site was $23,517 for EF and $19,118 for IF. EF yielded more FOCUS users at each center, such that the average monthly financial costs were lower for EF ($167 per client [N=129]) than for IF ($177 per client [N=81]). When using a real-world scenario based on economic costs and a lower organizational indirect rate, the average monthly cost per client was $73 for EF and $59 for IF. Both models reflected substantial cost reductions (about 50%) relative to a previous deployment of FOCUS in a clinical trial. Compared with IF, EF yielded more clients who received mHealth at community mental health centers and had comparable or lower costs.

An optimal sensor design framework accounting for sensor reliability over the structural life cycle

One of the most prominent goals of a structural health monitoring (SHM) system is to infer the state of the structure to inform appropriate maintenance actions that affect performance and safety over the life cycle of the structure. SHM necessarily involves data acquisition at the beginning of the SHM workflow, but damage state inference may be fundamentally flawed if the sensing system itself initiates unreliable data. The operational and environmental conditions that these sensors face, in addition to normal manufacturing defects, may result in varying functionality in both space and time. Therefore, it becomes imperative to account for sensor reliability in the optimal sensor design process for the SHM system at the outset – that is, consider the possibility of sensors malfunctioning in the initial/pre-posterior design stage without the benefit of previous deployment information – such that the initial design is robust to sensor malfunction with regard to decision performance objectives. This paper details an optimal sensor design framework at the pre-posterior stage that incorporates the time-dependent reliability of the sensor network over the life cycle of the structure. The proposed framework can be used to obtain an intelligent initial design that can be updated with time, based on the principles and procedure presented here, but by considering the updated/current state of the structure. The generic framework is laid out and is finally demonstrated on a complex real-world miter-gate structure.

Double-Agent Reinforced vNFC Deployment in EONs for Cloud-Edge Computing

With an effective service provisioning strategy that relies on Network Function Virtualization (NFV), cloud-edge computing can enhance the Quality of Service (QoS) in Elastic Optical Networks (EONs). NFV emerges as a promising technology to provide flexible services by orchestrating different virtual Network Function Chains (vNFCs). However, the vNFC deployment process is complex and involves two stages, i.e., allocating diverse Virtual Network Functions (VNFs) onto different physical nodes and routing suitable paths for Virtual Links (VLs). How to coordinate the above two stages to deploy vNFCs efficiently in EONs for cloud-edge computing is extremely important. Previous vNFC deployment algorithms are heuristic policies that disregard heterogeneous characteristics in cloud-edge computing. Recently, single-agent Deep Reinforcement Learning (DRL) can provide adaptive allocation schemes by perceptual learning from the environment. Whereas, its performance is not as good as expected since it makes the process of VFNs deployment and VLs deployment independent. Therefore, we propose a Double-Agent Reinforced vNFC Deployment algorithm (DARD) to integrate the VNFs and VLs deployment stages by two cooperative DRL agents. Additionally, we formulate the vNFC deployment problem as a Mixed Integer Linear Programming (MILP) model to achieve optimal solutions. The performance of DARD is evaluated in both static and dynamic scenarios. Simulation results show that DARD can achieve approaching performance with the MILP model. Moreover, it performs better than the other five state-of-art algorithms.

Midterm Outcomes of Primary and Secondary Use of an Endoanchor System for Thoracic and Abdominal Aortic Endovascular Aortic Repair

PurposeTo assess the safety, technical success, and midterm outcomes of endoanchor (Heli-FX, Medtronic, Santa Rosa, California) deployment in thoracic endovascular aortic repair (TEVAR) or abdominal endovascular aortic repair (EVAR). Materials and MethodsThis single-institution, retrospective study of all endoanchor procedures was performed from February 1, 2017 to March 30, 2021. All procedures were performed percutaneously by interventional radiologists. Clinical information and outcome data were retrieved from electronic medical records. Fifty patients (14% females, n = 7; 86% males, n = 43; median age, 79 years [range, 56–93 years]) underwent Endoanchor procedures, with 349 Endoanchors implanted; 33 procedures were primary deployments (at initial stent deployment) and 17 were secondary deployments (previous stent deployment). For the primary group (4 TEVARs and 29 EVARs), indications were prophylactic (n = 30), hostile neck (n = 28), hostile distal landing zone (n = 2), and intraprocedural type 1a endoleaks (n = 3). For the secondary group (4 TEVARs and 13 EVARs), indications were graft migration (n = 8), seal zone expansion without proven endoleak (n = 7) (proximal [n = 4] or distal seal [n = 3]), and proven type 1a endoleak (n = 2). ResultsMedian number of endoanchors deployed per procedure was 7 (range, 3–10). Median time to deploy endoanchors was 22 minutes (range, 8–46 minutes). The technical success rate of Endoanchor was 99.7% (348/349). The 30-day mortality rate was 0%. The overall adverse event rate was 6% (n = 3). Reinterventions were performed in 12% of patients (n = 6). Median follow-up was 38 months (range, 2–71 months). Overall survival at 1 and 3 years was 95% and 85%, respectively. Overall freedom from type 1a endoleak at 1 and 3 years was 96% and 93%, respectively. ConclusionsEndoanchor procedures are safe with excellent technical success rate and good midterm clinical outcomes.

Endoscopic reintervention after unilateral metal stent deployment for MHBO using SIS method.

Endoscopic biliary drainage is the main treatment for unresectable malignant hilar biliary obstruction (MHBO). Recurrent biliary obstruction (RBO) often occurs after unilateral metal stent deployment. Endoscopic reintervention can be complex for this problem, especially for drainage of the contralateral bile duct. The stent-in-stent (SIS) method is a possible solution to this problem. Our objective was to evaluate the safety and feasibility of the SIS method for endoscopic reintervention in patients with RBO due to MHBO after unilateral metal stent deployment. Eleven patients with MHBO received endoscopic reintervention using the SIS method to manage RBO after unilateral metal stent deployment. Clinical data, including technical and clinical success, procedure time, adverse events and complications, stent patency, RBO of the revisionary stent, and survival time were recorded. Nine patients (82%) achieved technical success, and all 9 of them also achieved clinical success. The 2 unsuccessful cases received percutaneous transhepatic cholangial drainage. The median procedure time was 73 minutes. The 3 adverse events were post-endoscopic retrograde cholangiopancreatography pancreatitis, cholangitis, and liver abscess. 6 patients (67%) experienced RBO of the revisionary stent, the median time to RBO of the revisionary stent was 95.5 days, the median survival time after reintervention was 111 days, and the median overall survival time was 305.5 days. Endoscopic reintervention after previous unilateral metal stent deployment using the SIS method appears to be safe and technically feasible for MHBO patients who experience RBO.

Preliminary Results from a Dense Short-Period Seismic Deployment around the Source Zone of the 1886 M 7 South Carolina Earthquake

Abstract The 1886 magnitude ∼7 Summerville, South Carolina, earthquake was the largest recorded on the east coast of the United States. A better understanding of this earthquake would allow for an improved evaluation of the intraplate seismic hazard in this region. However, its source fault structure remains unclear. Starting in May 2021, a temporary 19-station short-period seismic network was deployed in the Summerville region. Here, we present our scientific motivation, station geometry, and quality of the recorded seismic data. We also show preliminary results of microearthquake detections and relocations using recordings from both our temporary and four permanent stations in the region. Starting with 52 template events, including two magnitude ∼3 events on 27 September 2021, we perform a matched filter detection with the one year of continuous data, resulting in a catalog of 181 total events. We then determine precise relative locations of a portion of these events using differential travel-time relocation methods, and compare the results with relocation results of 269 events from a previous seismic deployment in 2011–2012. We also determine focal mechanism solutions for three events from 27 September 2021 with magnitudes 2.0, 3.1, and 3.3, and infer their fault planes. Our relocation results show a south-striking west-dipping zone in the southern seismicity cluster, which is consistent with the thrust focal mechanism of the magnitude 3.3 earthquake on 27 September 2021 and results from the previous study based on the temporary deployment in 2011–2012. In comparison, the magnitudes 3.1 and 2.0 events likely occur on a north–south-striking right-lateral strike-slip fault further north, indicating complex patterns of stress and faulting styles in the region.

The Russian invasion and its failure in the first days

ABSTRACT In February 2022, Russia launched a large-scale military operation to take full control of the Ukrainian state. The invasion achieved virtually none of Russia's originally stated goals and instead of demonstrating Russian military power and effectiveness, it showed the exact opposite. Ambitious goals that were supposed to be achieved within a few days, turned out to be completely unrealistic. The war has become a long-term conflict of high intensity, instead of a flash military operation. The author argues that the cause of the Russian failure was not only the erroneous intelligence evaluation of the adversary by the Russian intelligence services and numerous mistakes of Russian units at the tactical and operational level. Rather, failure has also been due the structural weaknesses and shortcomings of the Russian army as institution. These long-term shortcomings were identified during the previous combat deployment of Russian forces in local conflicts and have never been resolved.

Exploring help-seeking patterns of UK veterans with mental health difficulties: Referrals to Combat Stress 2012–2022

BackgroundExploration of help-seeking by UK veterans with mental health difficulties has traditionally focused on barriers and facilitators to action. Comparatively little is known concerning referral patterns to specialist veteran mental health services. AimsTo explore patterns of help-seeking over the decade to 2022 to a national specialist mental health service for UK military veterans. MethodsA dataset was created from electronic patient records for referrals between 2012 and 2022. Data included demographics, dates of referral, military service details including service length and operational deployments. ResultsThe mean time taken for veterans to seek help after leaving service appeared to modestly increase, when compared to previous studies. This is contrary to predictions from previous studies and potentially driven by a cohort effect of older veterans continuing to take longer to seek support than their younger peers. Further, early service leavers took longer to seek help. Over the course of the decade, the proportion of veterans with experience of operations in Iraq and/or Afghanistan increased; these individuals appeared to seek help more quickly than veterans who had served on previous deployments. The proportion of female veterans seeking referral increased over time. ConclusionsAlthough older veterans continue to present with mental health difficulties, those younger and with more recent deployment to Afghanistan are likely to represent the largest group seeking help in the coming years. These trends indicate that adequate specialist veteran mental health care provision is contingent on meeting the needs of veterans with a range of demographic and military profiles.

3-D shallow shear velocity structure of the Jakarta Basin from transdimensional ambient noise tomography.

Situated on the northern coast of the Indonesian island of Java, Jakarta and its metropolitan area (Greater Jakarta) are subject to significant earthquake hazards from a subduction zone south of Java and nearby active crustal faults. The seismic risk may be even higher because Greater Jakarta resides on a sedimentary basin filled with thick Pliocene-Pleistocene sediments. A comprehensive study of Jakarta Basin's properties and geometry is important for creating robust seismic hazard and risk assessments. The main objective of this study is to develop a 3-D model of Jakarta Basin's shallow shear-wave velocity (VS ) structure and improve on previous models that did not cover the basin edge due to the extent of data coverage. Between April and October 2018, we deployed a new temporary seismic network to extend the spatial coverage beyond that of a previous deployment in 2013, and sampled 143 locations through sequential deployments of 30 broad-band sensors covering Jakarta and its adjacent areas. We conducted a 2-stage transdimensional Bayesian inversion of Rayleigh wave phase velocity dispersion curves derived from seismic noise. To begin, we applied tomography and constructed 2-D phase velocity maps for periods 1-5s. Then, at each point in a regular grid defined on these maps, we invert each dispersion curve into 1-D depth profiles of VS . Finally, these profiles at gridpoints with ∼2km spacing are interpolated to form a pseudo-3-D VS model. Our results reveal the edge of the Pliocene-Pleistocene sediments along the south. Also, we resolve a basement offset across south Jakarta that we suggest may be related to the western extension of the Baribis Fault (alternatively, the West Java Backarc Thrust). We recommend using this 3-D model of the Jakarta Basin for scenario earthquake ground motion simulations. Such simulations would help establish how important it might be to re-assess seismic hazard and risk in Greater Jakarta so that basin resonance and amplification are considered.

H/V Analysis in Juchitán de Zaragoza, Oaxaca, Following the 2017 M 8.2 Tehuantepec, México, Earthquake

ABSTRACT In September 2017, over 450 lives were lost in Mexico as a result of two unusual, large-magnitude, normal earthquakes. On 7 September, an M 8.2 earthquake occurred offshore of the State of Oaxaca in the Gulf of Tehuantepec, one of the largest extensional earthquakes to have occurred in a subduction zone. Twelve days later on 19 September an M 7.1 damaging earthquake struck near Puebla and Morelos, over 600 km away. Both earthquakes occurred in the downgoing Cocos plate, which is subducting beneath the North American plate. The first large event was followed on 23 September by a shallow M 6.1 extensional earthquake near Juchitán de Zaragoza, Oaxaca. Researchers from Mexico and the United States collaborated to deploy a temporary seismic network to study the aftershocks of the M 8.2 Tehuantepec, Mexico, earthquake, which included a three-week deployment of 51 Magseis Fairfield Z-Land 5-Hz three-component nodal seismometers (“nodes”) near Juchitán and a 6-month deployment of 10 Nanometrics Trillium 120PA broadband seismometers with Reftek RT130 dataloggers for 6 months. In this article, we analyze the capabilities of the nodes to calculate the horizontal/vertical (H/V) spectral ratio and relative amplification using both microtremors and earthquakes and validate the results calculated with the nodes using data from broadband stations from this and previous deployments in the area. We create maps showing a correlation of the distribution of the fundamental frequency and relative amplification of the soil and compare them with the geology and the damage caused by the September 2017 earthquakes. There is a lack of public awareness and discrepancies in the construction procedures in the region, and we find that the majority of damaged houses in the area of study followed the location of river beds and tended to be in places with low resonance frequencies despite being in a low amplification zone.

Avoiding the “Great Filter”: An assessment of climate change solutions and combinations for effective implementation

Global climate temperatures have unmistakably risen, and naturally occurring climate variability alone cannot account for this trend. Human activities are estimated to have caused about 1°C of global warming above the preindustrial baseline, and if left unchecked, it will continue to drastically damage the Earth and its inhabitants. Attempts toward alleviating the effects of global warming have often been at odds and remain divided among a multitude of strategies, reducing the overall effectiveness of these efforts. It is evident that collaborative action is required for avoiding the most severe consequences of climate change. This article evaluates the main strategies (industrial/energy, political, economic, agricultural, atmospheric, geological, coastal, and social) toward both mitigating and adapting to climate change. Also, it provides an optimal combination of seven solutions that can be implemented simultaneously, working in tandem to limit and otherwise accommodate the harmful effects of climate change. Previous legislation and deployment techniques are also discussed as guides for future endeavors.

Learning to Broadcast for Ultra-Reliable Communication With Differential Quality of Service via the Conditional Value at Risk

Broadcast/multicast communication systems are typically designed to optimize the outage rate criterion, which neglects the performance of the fraction of clients with the worst channel conditions. Targeting ultra-reliable communication scenarios, this paper takes a complementary approach by introducing the conditional value-at-risk (CVaR) rate as the expected rate of a worst-case fraction of clients. To support differential quality-of-service (QoS) levels in this class of clients, layered division multiplexing (LDM) is applied, which enables decoding at different rates. Focusing on a practical scenario in which the transmitter does not know the fading distribution, layer allocation is optimized based on a dataset sampled offline. The optimality gap caused by the availability of limited data is bounded via a generalization analysis, and the sample complexity is shown to increase as the designated fraction of worst-case clients decreases. Considering this theoretical result, meta-learning is introduced as a means to reduce sample complexity by leveraging data from previous deployments. Numerical experiments demonstrate that LDM improves spectral efficiency even for small datasets; that, for sufficiently large datasets, the proposed mirror-descent-based layer optimization scheme achieves a CVaR rate close to that achieved when the transmitter knows the fading distribution; and that meta-learning can significantly reduce data requirements.