3D architecture and complex behavior along the simple central San Andreas fault.

The central San Andreas Fault (CSAF) exhibits a simple linear large-scale fault geometry, yet seismic and aseismic deformation features vary in a complex way along the fault. Here we investigate fault zone behaviors using geodetic observation, seismicity and microearthquake focal mechanisms. We employ an improved focal-mechanism characterization method using relative earthquake radiation patterns on 75,164 Ml ≥ 1 earthquakes along a 2-km-wide, 190-km-long segment of the CSAF, from 1984 to 2015. The data reveal the 3D fine-scale structure and interseismic kinematics of the CSAF. Our findings indicate that the first-order spatial variations in interseismic fault creep rate, creep direction, and the fault zone stress field can be explained by a simple fault coupling model. The inferred 3D mechanical properties of a mechanically weak and poorly coupled fault zone provide a unified understanding of the complex fine-scale kinematics, indicating distributed slip deficits facilitating small-to-moderate earthquakes, localized stress heterogeneities, and complex multi-scale ruptures along the fault. Through this detailed mapping, we aim to relate the fine-scale fault architecture to potential future faulting behavior along the CSAF.

Toward Structural Health Monitoring with the MyShake Smartphone Network.

The field of structural health monitoring (SHM) faces a fundamental challenge related to accessibility. While analytical and empirical models and laboratory tests can provide engineers with an estimate of a structure's expected behavior under various loads, measurements of actual buildings require the installation and maintenance of sensors to collect observations. This is costly in terms of power and resources. MyShake, the free seismology smartphone app, aims to advance SHM by leveraging the presence of accelerometers in all smartphones and the wide usage of smartphones globally. MyShake records acceleration waveforms during earthquakes. Because phones are most typically located in buildings, a waveform recorded by MyShake contains response information from the structure in which the phone is located. This represents a free, potentially ubiquitous method of conducting critical structural measurements. In this work, we present preliminary findings that demonstrate the efficacy of smartphones for extracting the fundamental frequency of buildings, benchmarked against traditional accelerometers in a shake table test. Additionally, we present seven proof-of-concept examples of data collected by anonymous and privately owned smartphones running the MyShake app in real buildings, and assess the fundamental frequencies we measure. In all cases, the measured fundamental frequency is found to be reasonable and within an expected range in comparison with several commonly used empirical equations. For one irregularly shaped building, three separate measurements made over the course of four months fall within 7% of each other, validating the accuracy of MyShake measurements and illustrating how repeat observations can improve the robustness of the structural health catalog we aim to build.

Detecting damaged buildings using real-time crowdsourced images and transfer learning.

After significant earthquakes, we can see images posted on social media platforms by individuals and media agencies owing to the mass usage of smartphones these days. These images can be utilized to provide information about the shaking damage in the earthquake region both to the public and research community, and potentially to guide rescue work. This paper presents an automated way to extract the damaged buildings images after earthquakes from social media platforms such as Twitter and thus identify the particular user posts containing such images. Using transfer learning and ~ 6500 manually labelled images, we trained a deep learning model to recognize images with damaged buildings in the scene. The trained model achieved good performance when tested on newly acquired images of earthquakes at different locations and when ran in near real-time on Twitter feed after the 2020 M7.0 earthquake in Turkey. Furthermore, to better understand how the model makes decisions, we also implemented the Grad-CAM method to visualize the important regions on the images that facilitate the decision.

Global growth of earthquake early warning.

Public-private partnerships provide a method for vastly expanding sensor networks.

Applying Movement Ecology to Marine Animals with Complex Life Cycles.

Marine animals with complex life cycles may move passively or actively for fertilization, dispersal, predator avoidance, resource acquisition, and migration, and over scales from micrometers to thousands of kilometers. This diversity has catalyzed idiosyncratic and unfocused research, creating unsound paradigms regarding the role of movement in ecology and evolution. The emerging movement ecology paradigm offers a framework to consolidate movement research independent of taxon, life-history stage, scale, or discipline. This review applies the framework to movement among life-history stages in marine animals with complex life cycles to consolidate marine movement research and offer insights for scientists working in aquatic and terrestrial realms. Irrespective of data collection or simulation strategy, breaking each life-history stage down into the fundamental units of movement allows each unit to be studied independently or interactively with other units. Understanding these underlying mechanisms of movement within each life-history stage can then be used to construct lifetime movement paths. These paths can allow further investigation of the relative contributions and interdependencies of steps and phases across a lifetime and how these paths influence larger research topics, such as population-level movements.

Quantitative trait loci for sensitivity to acute ethanol and ethanol consummatory behaviors in rats.

Individuals with a low initial response to alcohol (i.e., ethanol) are at greater risk of developing alcohol abuse or dependence later in life. Similar to humans, individual differences in ethanol sensitivity also can be seen in rats, and several laboratories have used these individual differences to generate selectively bred rats that differ in acute ethanol sensitivity. We have worked with two sets of such rats (Inbred High or Low Alcohol Sensitivity strains, IHAS or ILAS, respectively; Inbred Alcohol Tolerant or Non-Tolerant strains, IAT and IANT, respectively) and have confirmed previously mapped quantitative trait loci (QTL) for these acute differences with the use of recombinant congenic lines; however, the relationship between acute sensitivity and ethanol drinking in these rats has yet to be determined. Thus, here we tested the hypothesis that QTLs underlying variation in initial low sensitivity to ethanol also will modulate variation in ethanol drinking behaviors. Separate groups of selectively inbred parent and congenic rats were tested for the loss of righting response (LORR) and also assessed for ethanol consummatory behavior using either operant self-administration or an intermittent-access two-bottle choice procedure. LORR testing confirmed the presence of a LORR duration QTL in all of the congenics; however, the lack of a corresponding difference in blood ethanol concentration at the regaining of the righting response suggests that these QTLs may be mediating a difference in ethanol metabolism rather than in neuronal sensitivity. IHAS/ILAS-derived congenic rats did not differ from parent rats at any point during operant self-administration. IAT/IANT-derived congenic rats showed small, but significant, increases in ethanol consumption relative to the parent strains only during the initial stages of operant self-administration. In contrast to operant testing, IHAS/ILAS-derived congenic rats showed significantly greater ethanol consumption and preference than parent rats during intermittent-access testing. There were not differences, however, between IAT/IANT congenic and parent rats during intermittent access. These data support the hypothesis that there is a genetic relationship between initial ethanol sensitivity and ethanol consumption, at least for the IHAS/ILAS-derived congenic rats. Our current studies, however, cannot eliminate pharmacokinetic or taste preference factors as contributing to the rats' responses, nor can we eliminate the possibility of a linkage effect because of the fairly large size of the QTL intervals; i.e., distinct genes may be mediating the acute sensitivity and drinking responses.

Tomography reveals buoyant asthenosphere accumulating beneath the Juan de Fuca plate.

The boundary between Earth's strong lithospheric plates and the underlying mantle asthenosphere corresponds to an abrupt seismic velocity decrease and electrical conductivity increase with depth, perhaps indicating a thin, weak layer that may strongly influence plate motion dynamics. The behavior of such a layer at subduction zones remains unexplored. We present a tomographic model, derived from on- and offshore seismic experiments, that reveals a strong low-velocity feature beneath the subducting Juan de Fuca slab along the entire Cascadia subduction zone. Through simple geodynamic arguments, we propose that this low-velocity feature is the accumulation of material from a thin, weak, buoyant layer present beneath the entire oceanic lithosphere. The presence of this feature could have major implications for our understanding of the asthenosphere and subduction zone dynamics.

MyShake: A smartphone seismic network for earthquake early warning and beyond.

Large magnitude earthquakes in urban environments continue to kill and injure tens to hundreds of thousands of people, inflicting lasting societal and economic disasters. Earthquake early warning (EEW) provides seconds to minutes of warning, allowing people to move to safe zones and automated slowdown and shutdown of transit and other machinery. The handful of EEW systems operating around the world use traditional seismic and geodetic networks that exist only in a few nations. Smartphones are much more prevalent than traditional networks and contain accelerometers that can also be used to detect earthquakes. We report on the development of a new type of seismic system, MyShake, that harnesses personal/private smartphone sensors to collect data and analyze earthquakes. We show that smartphones can record magnitude 5 earthquakes at distances of 10 km or less and develop an on-phone detection capability to separate earthquakes from other everyday shakes. Our proof-of-concept system then collects earthquake data at a central site where a network detection algorithm confirms that an earthquake is under way and estimates the location and magnitude in real time. This information can then be used to issue an alert of forthcoming ground shaking. MyShake could be used to enhance EEW in regions with traditional networks and could provide the only EEW capability in regions without. In addition, the seismic waveforms recorded could be used to deliver rapid microseism maps, study impacts on buildings, and possibly image shallow earth structure and earthquake rupture kinematics.

Escalation of cocaine consumption in short and long access self-administration procedures.

BACKGROUND: Escalation of consumption is a hallmark of cocaine addiction. Many animal models reveal escalation by increasing the duration of drug access (e.g., 6-24 h/day) after longer histories of self-administration. We recently developed a method that reveals escalation early post-acquisition under shorter access conditions. However, whether or not rats will escalate cocaine consumption both early post-acquisition under short access (2 h/day) conditions, and later under long access (6 h/day) conditions, has not been demonstrated. METHODS: All rats acquired cocaine self-administration (0.8 mg/kg, i.v.) under 2 h conditions, and then continued 2h self-administration for an additional 13 sessions. Then, rats were assigned either to 2 or 6h conditions, and self-administered cocaine (0.8 mg/kg, i.v.) for an additional 19 sessions. In addition, four cocaine-induced locomotor activity measurements were taken for each rat: before cocaine exposure, after non-contingent cocaine administration, and after escalation in the short and long access experimental phases. RESULTS: Following acquisition, rats displayed a robust escalation of intake during 2 h sessions. Rats that self-administered cocaine in continued 2h sessions exhibited stable intake, whereas rats that self-administered cocaine in 6h sessions further escalated intake. Despite the second escalation in 6h rats, cocaine-induced locomotor activity did not differ between 2 and 6h rats. CONCLUSIONS: Escalation of cocaine self-administration can occur in the same rats both early post-acquisition, and later under long access conditions. Importantly, this early post-acquisition period provides a new opportunity to determine the mechanisms first involved in the escalation phenomenon.

Continuous exposure to dizocilpine facilitates the acquisition and escalation of cocaine consumption in male Sprague-Dawley rats.

BACKGROUND: Blocking N-methyl-d-aspartate (NMDA) glutamate receptors (NMDARs) prevents cocaine locomotor sensitization, but facilitates escalation of cocaine self-administration and produces ambiguous effects on acquisition of cocaine self-administration. This study used a recently described model of acquisition and escalation to test the hypothesis that continuous NMDAR antagonism functionally increases the effects of a given dose of cocaine. METHODS: We assessed acquisition of cocaine self-administration (0.6 mg/kg/infusion) in rats treated continuously with either vehicle or the NMDAR antagonist dizocilpine (0.4 mg/kg/day) for 14 consecutive 2h fixed ratio 1 (FR1) sessions. In a separate experiment that assessed the effect of dizocilpine treatment on escalation of cocaine self-administration, rats acquired cocaine self-administration (0.6 mg/kg/infusion) prior to vehicle or dizocilpine treatment. Then, immediately post-acquisition, rats were treated continuously with either vehicle or dizocilpine and allowed to self-administer either 0.6 or 1.2mg/kg/infusion cocaine for an additional seven consecutive 2h FR1 sessions. RESULTS: Relative to vehicle-treated rats, a significantly greater percentage of dizocilpine-treated rats acquired cocaine self-administration. During the escalation experiment, both vehicle- and dizocilpine-treated rats escalated intake of 1.2mg/kg/infusion cocaine. Whereas vehicle-treated rats exhibited stable intake of 0.6 mg/kg/infusion cocaine, dizocilpine-treated rats escalated intake of this moderate cocaine dose to levels indistinguishable from intake levels produced by self-administration of the high cocaine dose (i.e., 1.2mg/kg/infusion). CONCLUSIONS: These findings suggest that chronic NMDAR blockade potentiates, rather than attenuates, cocaine's effects and argue for reconsideration of the role of NMDARs in cocaine "addiction-like" behavior.

Egg size effects across multiple life-history stages in the marine annelid Hydroides diramphus.

The optimal balance of reproductive effort between offspring size and number depends on the fitness of offspring size in a particular environment. The variable environments offspring experience, both among and within life-history stages, are likely to alter the offspring size/fitness relationship and favor different offspring sizes. Hence, the many environments experienced throughout complex life-histories present mothers with a significant challenge to optimally allocate their reproductive effort. In a marine annelid, we tested the relationship between egg size and performance across multiple life-history stages, including: fertilization, larval development, and post-metamorphosis survival and size in the field. We found evidence of conflicting effects of egg size on performance: larger eggs had higher fertilization under sperm-limited conditions, were slightly faster to develop pre-feeding, and were larger post-metamorphosis; however, smaller eggs had higher fertilization when sperm was abundant, and faster planktonic development; and egg size did not affect post-metamorphic survival. The results indicate that egg size effects are conflicting in H. diramphus depending on the environments within and among life-history stages. We suggest that offspring size in this species may be a compromise between the overall costs and benefits of egg sizes in each stage and that performance in any one stage is not maximized.

Continuous exposure to dizocilpine facilitates escalation of cocaine consumption in male Sprague-Dawley rats.

BACKGROUND: Although the escalation of cocaine consumption is a hallmark of cocaine dependence, the neurobiological mechanisms that underlie this change in behavior are not well understood. METHODS: This study used an extended access version of the drug self-administration procedure to explore how N-methyl-d-aspartate (NMDA) receptors are involved in escalation of cocaine consumption. Male Sprague-Dawley rats (n=59) were first trained to self-administer cocaine (0.33 mg/infusion, i.v.) under a fixed-ratio 1 (FR1) schedule of reinforcement. After training, rats were implanted with subcutaneous osmotic minipumps filled with vehicle or the non-competitive NMDAR antagonist, dizocilpine (0.2 or 0.4 mg/kg/d), and subsequently allowed to self-administer cocaine in 2h or 6h self-administration sessions. RESULTS: In the 6h groups, vehicle-treated rats escalated cocaine self-administration across 15 self-administration sessions; rats treated with dizocilpine escalated cocaine self-administration at a greater rate and to a greater degree. Rats that self-administered cocaine during 2h sessions did not escalate consumption of cocaine under any treatment condition. Discontinuation of dizocilpine treatment in the 6h access condition led to a substantial decrease in cocaine consumption, down to pre-escalation levels, and then control rates of escalation thereafter. Despite large differences in intake under the FR1 schedule, post-escalation break point under a progressive ratio schedule of reinforcement did not differ between groups. CONCLUSION: These data suggest that glutamate tone through NMDA receptors can play a dynamic role in regulating cocaine intake and escalation of consumption.

Low- and high-cocaine locomotor responding rats differ in reinstatement of cocaine seeking and striatal mGluR5 protein expression.

Behavioral responsiveness to initial cocaine use varies among individuals and may contribute to differential vulnerability to cocaine addiction. Rats also exhibit individual differences in cocaine's effects and can be classified as low or high cocaine responders (LCRs or HCRs, respectively), based on their initial cocaine-induced locomotor activity (10 mg/kg, i.p.). Here, we used the extinction/reinstatement model to address whether or not LCRs and HCRs differ in (i) extinction/reinstatement of cocaine self-administration behavior and (ii) levels of metabotropic glutamate receptors (mGluRs) following these behaviors. During the earliest acquisition sessions, LCRs exhibited significantly greater cocaine intake (0.8 mg/kg/infusion) and cocaine-paired lever responding than HCRs, but intake and lever responding converged by the end of the cocaine self-administration portion of the study. LCRs and HCRs did not differ in cocaine seeking during the first extinction session and extinguished cocaine seeking similarly. HCRs exhibited greater reinstatement than LCRs to lower (2.5 and 5 mg/kg), but not higher (10 mg/kg), i.p. priming doses of cocaine. The effect of drug-paired cues on reinstatement following extinction was complex, with HCRs and LCRs showing the greater effect of cue depending on the order in which cue- and drug-primed tests were given. Western blot analysis revealed that mGluR5 heteromers were significantly higher in the dorsal striatum of HCRs than LCRs following reinstatement testing. Although our previous findings with the LCR/HCR model have uniformly supported the idea that lower initial cocaine-induced activation predicts more ready development of cocaine addiction-like behaviors, here, we show a more complex relationship with cocaine reinstatement.

Rats classified as low or high cocaine locomotor responders: a unique model involving striatal dopamine transporters that predicts cocaine addiction-like behaviors.

Individual differences are a hallmark of drug addiction. Here, we describe a rat model based on differential initial responsiveness to low dose cocaine. Despite similar brain cocaine levels, individual outbred Sprague-Dawley rats exhibit markedly different magnitudes of acute cocaine-induced locomotor activity and, thereby, can be classified as low or high cocaine responders (LCRs or HCRs). LCRs and HCRs differ in drug-induced, but not novelty-associated, hyperactivity. LCRs have higher basal numbers of striatal dopamine transporters (DATs) than HCRs and exhibit marginal cocaine inhibition of in vivo DAT activity and cocaine-induced increases in extracellular DA. Importantly, lower initial cocaine response predicts greater locomotor sensitization, conditioned place preference and greater motivation to self-administer cocaine following low dose acquisition. Further, outbred Long-Evans rats classified as LCRs, versus HCRs, are more sensitive to cocaine's discriminative stimulus effects. Overall, results to date with the LCR/HCR model underscore the contribution of striatal DATs to individual differences in initial cocaine responsiveness and the value of assessing the influence of initial drug response on subsequent expression of addiction-like behaviors.

Cocaine dose and self-administration history, but not initial cocaine locomotor responsiveness, affects sensitization to the motivational effects of cocaine in rats.

Cocaine addiction is a significant and complex disease. Part of this complexity is caused by the variability of the drug experience early in drug use (initial responsiveness, amount of use, etc.). In rats, individual differences in initial cocaine responsiveness and cocaine self-administration history both predict the development of cocaine sensitization, a putative mechanism contributing to the development of cocaine addiction. Here, we sought to determine the role of these factors and cocaine dose on the development of sensitization to cocaine's motivational effects during the earliest stages of self-administration. Rats were classified as either low or high cocaine responders (LCRs or HCRs, respectively) based on acute cocaine-induced locomotor activity (10 mg/kg i.p.) before learning to self-administer cocaine (0.6 mg/kg/infusion i.v.) under a fixed ratio 1 (FR1) schedule of reinforcement. After acquisition, rats self-administered cocaine (0.6 or 1.2 mg/kg/infusion) under a progressive ratio (PR) schedule of reinforcement either immediately or after an additional five FR1 sessions (0.6 or 1.2 mg/kg/infusion). No LCR/HCR differences in sensitization were observed. However, regardless of LCR/HCR classification, exposure to the higher dose of cocaine produced sensitization to cocaine's motivational effects on the PR schedule (i.e., increased break points) and an escalation of consumption on the FR schedule. Thus, our results reveal a novel model for studying escalation and sensitization very early after acquisition and suggest that sensitization may be important in the earliest stages of the cocaine addiction process.

Acquisition of cocaine self-administration in male Sprague-Dawley rats: effects of cocaine dose but not initial locomotor response to cocaine.

RATIONALE: We have previously described a model in which adult outbred male Sprague-Dawley rats are classified as either low or high cocaine responders (LCRs or HCRs, respectively) based on acute cocaine-induced open-field activation. This model revealed important individual differences in cocaine's effects, including that LCRs exhibited greater responding than HCRs on a progressive ratio schedule of cocaine reinforcement. However, no LCR/HCR differences in acquisition of cocaine self-administration (0.25 mg/kg/12 s infusion) were observed under these conditions. OBJECTIVES: To determine if LCRs and HCRs differ in the effectiveness of cocaine to function as a reinforcer under a broader range of conditions, the present study assessed the acquisition of cocaine self-administration (fixed ratio 1 schedule of reinforcement) as a function of i.v. cocaine dose (0.1875, 0.375, 0.5, 1, or 1.5 mg/kg/6 s infusion). RESULTS: LCRs and HCRs did not differ significantly on any measure of acquisition examined, including the day to meet acquisition criterion, percent acquired, and cocaine intake. The effect of dose on percent acquired and rate of acquisition peaked at the 1-mg/kg/infusion dose of cocaine. In contrast, the effect of dose on cocaine intake was linear, with the highest rate of intake occurring at the 1.5-mg/kg/infusion dose of cocaine. CONCLUSIONS: LCRs and HCRs do not appear to differ in their acquisition of cocaine-reinforced operant responding across a range of cocaine doses, including conditions that lead to high levels of cocaine intake.

Individual differences in initial low-dose cocaine-induced locomotor activity and locomotor sensitization in adult outbred female Sprague-Dawley rats.

Sex and individual differences are important considerations when studying cocaine responsiveness. We have previously shown that male Sprague-Dawley (S-D) rats can be classified as low or high cocaine responders (LCRs or HCRs, respectively) based on their locomotor activity following a single dose of cocaine (10 mg/kg, i.p.). Further, this distinction was found to predict dopamine transporter function, cocaine-induced locomotor sensitization, cocaine conditioned place preference and motivation to self-administer cocaine. Here we investigated whether or not individual differences in cocaine-induced locomotor activity and locomotor sensitization exist in female S-D rats. Female rats exhibited a broad range of locomotor activation following either a 5 or 10 mg/kg cocaine injection, allowing for classification as LCRs or HCRs. When administered over 7 days, both doses induced locomotor sensitization in female LCRs/HCRs. However, the magnitude of effects produced by 5 mg/kg cocaine in female LCRs/HCRs was more comparable to that produced by 10 mg/kg in male LCRs/HCRs, both of which, interestingly, developed sensitization in this study. These findings suggest that female S-D rats, like male S-D rats, can be classified as LCRs/HCRs and highlight the importance of accounting for dose when studying sex and individual differences to the effects of cocaine.

Individual differences in cocaine-induced locomotor activity in male Sprague-Dawley rats and their acquisition of and motivation to self-administer cocaine.

RATIONALE: Factors that increase an individual's susceptibility to cocaine dependence remain largely unknown. We have previously shown that adult outbred male Sprague-Dawley rats can be classified as either low or high cocaine responders (LCRs or HCRs, respectively) based on their locomotor activity following the administration of a single dose of cocaine (10 mg/kg, i.p.). Furthermore, LCR/HCR classification predicts dopamine transporter function/inhibition, cocaine-induced locomotor sensitization, and cocaine-conditioned place preference. OBJECTIVES: The present study assessed LCR/HCR classification and the development of locomotor sensitization on the latency to acquire cocaine self-administration and motivation to self-administer cocaine. RESULTS: LCRs and HCRs did not differ in their latency to acquire low-dose cocaine self-administration (0.25 mg/kg/infusion over 12 s, fixed ratio 1 schedule of reinforcement). In a follow-up experiment, repeated experimenter-administered injections of cocaine (10 mg/kg, i.p.) resulted in locomotor sensitization for LCRs, but not HCRs; nonetheless, all rats exhibited decreased latency to acquire cocaine self-administration compared to the first experiment. Repeated cocaine preexposure and LCR/HCR classification predicted break point when rats responded for cocaine under a progressive ratio schedule of reinforcement (0.25, 0.5, and 1.0 mg/kg/infusion; multiple exposure>single exposure, LCR>HCR), but there was no interaction between these variables. CONCLUSIONS: Although LCR/HCR classification did not predict the rate of acquisition of cocaine self-administration under these conditions, LCR rats demonstrated greater responding for cocaine after acquisition (PR). Thus, these findings demonstrate the relevance of using the LCR/HCR model when studying susceptibility to cocaine dependence.