Sites In Mexico Research Articles

Migratory strategies across an ecological barrier: is the answer blowing in the wind?

BackgroundEcological barriers can shape the movement strategies of migratory animals that navigate around or across them, creating migratory divides. Wind plays a large role in facilitating aerial migrations and can temporally or spatially change the challenge posed by an ecological barrier, with beneficial winds potentially converting a barrier into a corridor. Here, we explore the role wind plays in shaping initial southbound migration strategy among individuals breeding at two sites along an ecological barrier.MethodsUsing GPS satellite transmitters, we tracked the southbound migrations of Short-billed Dowitchers (Limnodromus griseus caurinus) from two breeding sites in Alaska to nonbreeding sites in coastal Mexico. The breeding sites were positioned in distinct regions along an ecological barrier – the Gulf of Alaska. We investigated potential differences in migratory timing, wind availability, and tailwind support en route across the Gulf of Alaska between individuals breeding at the two sites.ResultsRoute choice and arrival timing to wintering sites differed markedly between the two breeding sites: individuals departing from the more westerly site left at the same time as those from further east but crossed the Gulf of Alaska farther west and arrived along the Pacific coast of Mexico an average of 19 days earlier than their counterparts. Dowitchers from both sites departed with slight tailwinds, but once aloft over the Gulf of Alaska, birds from the more westerly site had up to twelve times more tailwind assistance than birds from the more easterly one.ConclusionsThe distinct migration strategies and degree of wind assistance experienced by birds at these two breeding sites demonstrates how differences in wind availability along migratory routes can form the basis for intraspecific variation in migration strategies with potential carryover effects. Future changes in wind regimes may therefore interact with changes in habitat availability to influence migration patterns and migratory bird conservation.

Contemporary fires are less frequent but more severe in dry conifer forests of the southwestern United States

Wildfires in the southwestern United States are increasingly frequent and severe, but whether these trends exceed historical norms remains contested. Here we combine dendroecological records, satellite-derived burn severity, and field measured tree mortality to compare historical (1700-1880) and contemporary (1985-2020) fire regimes at tree-ring fire-scar sites in Arizona and New Mexico. We found that contemporary fire frequency, including recent, record fire years, is still <20% of historical levels. Since 1985, the fire return interval averages 58.8 years, compared to 11.4 years before 1880. Fire severity, however, has increased. At sites where trees historically survived many fires over centuries, 42% of recent fires resulted in high tree mortality. Suppressed wildfires tended to burn more severely than prescribed burns and wildfires managed for resource benefit. These findings suggest that expanded use of low-severity prescribed and managed fire would help restore forest resilience and historical fire regimes in dry conifer forests.

Concrete carbonation in tropical urban and urban/marine environments after 20 years of natural exposure

This work is part of the DURACON project, which seeks to characterize the durability of concrete exposed to environmental conditions prevailing in Ibero-America and is based on the exposure of unreinforced and reinforced concrete specimens in marine and urban environments in each participating Ibero-American country. This research presents the results obtained from exposing unreinforced and steel-reinforced concrete specimens to prevailing environmental conditions in twelve natural exposure sites in Mexico during an exposure period of approximately 20 years to determine an empirical model that allows predicting the value of the carbonation rate, k′CO2, as a function of the nth-root of time (NRT) for the concretes evaluated. The concrete specimens, plain and reinforced, exposed to the elements in these cities were manufactured with two types of concrete, one with a w/c ratio = 0.65 and the other with a w/c ratio = 0.45. The tests mainly focused on measuring the concrete carbonation front depth during the ∼ 20 years of exposure and the measurement of environmental parameters at the exposure sites, such as temperature, relative humidity, rainfall, and atmospheric CO2 concentration. The electrochemical parameters of the reinforcing steel (half-cell potential, Ecorr, and current density, icorr) in the reinforced specimens were also obtained after ∼ 20 years of exposure to corroborate which sites showed lower or higher corrosion activity. This model to obtain k′CO2 as a function of the environmental parameters of the Mexican exposure sites and the physical properties of the concretes was compared with the value of kCO2 obtained from the square root of time (SRT) model. It was found that the k′CO2 values were 30 % higher on average than the kCO2 obtained with the empirical SRT equation. However, it should be noted that k′CO2 must be linked to the corresponding nth-root of time, whereas the value of n to obtain kCO2 is constant and equal to ½. An agreement was also obtained between the probability of activation of the reinforcing steel, using the corrosion parameters (Ecorr and icorr), and the probability of eCO2 ≤ 15 mm (lowest concrete cover used in this study).

Breeding season temporal and spatial trends in continental-scale migration of the monarch butterfly.

The monarch butterfly (Danaus plexippus) is a vagile species that undertakes an annual, multi-generational migration across North America. The abundance of this species at both eastern and western overwintering sites in Central Mexico and California indicates a population decline. Success of continental-scale conservation programs for a migratory species depends on providing, maintaining, and protecting habitats at appropriate temporal and spatial scales. Here, dynamics of monarch continental-scale migration and gene flow were obtained by combined stable isotope, morphological, and genetic analyses. These analyses were applied to temporal monarch samples collected from May to September during 2016-2021 at locations in Iowa, USA and spatial collections from Pennsylvania, Delaware, Iowa, Ohio, Nevada, Idaho, Hawaii, 3 Australian locations during July and August 2016, and Texas in April 2021. Evidence of seasonal multi-generational migration was obtained through δ2H analyses of spatial collections, which was corroborated by decreased wing hue (a morphological marker for non-migratory individuals). In Iowa, 10-15% of monarchs represented migrants from southern areas throughout the breeding season and 6% were migrants from the North in midsummer. Limited sequence variation detected across the mitochondrial genome impacted the capability to detect significant population genetic variation in our North American samples. However, 2 novel substitutions were identified and predicted to be fixed among Australia samples, contributing to intercontinental differentiation from counterparts in North America. Our assessment of temporal and spatial population dynamics across the North American monarch breeding range provides insight into continental-scale migration and previously undetected mitochondrial DNA variation among globally distributed populations.

“Queer Errantry” In The Work Of Cristina Rivera Garza

In this essay I consider two books by the Mexican writer Cristina Rivera Garza – Había mucha neblina o humo o no sé qué (2016) [There Was a Lot of Fog or Smoke or I Don’t Know What] and Autobiografía del algodón (2020) [Autobiography of Cotton] which conjugate journeys to sites in Mexico where agricultural and industrial labour played a critical role in the country’s post-revolutionary reconstruction. I illustrate how these works not only spotlight the long-term effects of dispossession, transnational migration, and “slow violence” but also articulate an epistemology of what I call “queer errantry”. Drawing on ideas from Edouard Glissant, Anna Arabindan-Kesson, Gloria Anzaldúa, and Sara Ahmed, I argue that, in the context of significant environmental and gender violence in Mexico and its “visceraless” state, for Rivera Garza travel and pedestrianism function as acts of relation, forms of reckoning with the rapid acceleration of capitalist modernity. As a way of reading and representing the world, “queer errantry”, I suggest, comprises a decolonial feminist praxis of orientation and remembrance.

Thinning relationships of woody encroachers in a US southwestern shrubland

Woody plant encroachment degrades the economic and environmental potential of drylands by altering processes such as nutrient fluxes, ecohydrology, and ecosystem services. Though past research has investigated the encroachment process, relatively little is known about post-encroachment shrub community ecology. To better quantify dynamics within post-woody encroachment shrub communities, we combined USGS lidar height data and multispectral imagery to estimate shrub density, shrub height, shrub cover, and shrub volume across the Jornada Basin Long Term Ecological Research (JRN-LTER) site in southern New Mexico, USA. Structural estimates were analyzed in search of telltale signs of community competition, specifically, the presence of thinning relationships. Results demonstrated density-dependent thinning relationships in shrub communities of creosote and mesquite, indicating a large role for competition in arid shrub communities even at relatively low shrub densities and cover (∼35% cover). In addition, shrub volume estimates better modeled the expected thinning dynamics of shrub communities than shrub canopy cover measurements. Overall, our results indicate the utility of lidar data in extending two-dimensional descriptions of woody vegetation structure (i.e., woody canopy cover) into the critical third dimension (i.e., woody plant volume), as well as the relative importance of competition and demographic bottlenecks to vegetation structure in drylands.

Traceability and dispersion of highly toxic soluble phases from historical mine tailings: insights from Pb isotope systematics

Dispersion of potentially toxic elements associated with efflorescent crusts and mine tailings materials from historical mine sites threaten the environment and human health. Limited research has been done on traceability from historical mining sites in arid and semi-arid regions. Pb isotope systematics was applied to decipher the importance of identifying the mixing of lead sources involved in forming efflorescent salts and the repercussions on traceability. This research assessed mine waste (sulfide-rich and oxide-rich tailings material and efflorescent salts) and street dust from surrounding settlements at a historical mining site in northwestern Mexico, focusing on Pb isotope composition. The isotope data of tailings materials defined a trending line (R2 = 0.9); the sulfide-rich tailings materials and respective efflorescent salts yielded less radiogenic Pb composition, whereas the oxide-rich tailings and respective efflorescent salts yielded relatively more radiogenic compositions, similar to the geogenic component. The isotope composition of street dust suggests the dispersion of tailings materials into the surroundings. This investigation found that the variability of Pb isotope composition in tailings materials because of the geochemical heterogeneity, ranging from less radiogenic to more radiogenic, can add complexity during environmental assessments because the composition of oxidized materials and efflorescent salts can mask the geogenic component, potentially underestimating the influence on the environmental media.

Development of an operational trap for collection, killing, and preservation of triatomines (Hemiptera: Reduviidae): the kissing bug kill trap.

Surveillance of triatomines or kissing bugs (Hemiptera: Reduviidae: Triatominae), the insect vectors of Trypanosoma cruzi, a Chagas disease agent, is hindered by the lack of an effective trap. To develop a kissing bug trap, we made iterative improvements over 3 years on a basic design resulting in 7 trap prototypes deployed across field sites in Texas, United States and Northern Mexico, yielding the capture of 325 triatomines of 4 species (Triatoma gerstaeckeri [Stål], T. sanguisuga [LeConte], T. neotomae [Neiva], and T. rubida [Uhler]). We began in 2019 with vertical transparent tarpaulin panel traps illuminated with artificial light powered by AC current, which were successful in autonomous trapping of flying triatomines, but were expensive, labor-intensive, and fragile. In 2020, we switched to white LED lights powered by a solar cell. We tested a scaled-down version of the vertical panel traps, a commercial cross-vane trap, and a multiple-funnel trap. The multiple-funnel traps captured 2.6× more kissing bugs per trap-day than cross-vane traps and approached the performance of the vertical panel traps in number of triatomines captured, number of triatomines per trap-day and triatomines per arthropod bycatch. Multiple-funnel traps required the least labor, were more durable, and had the highest triatomines per day per cost. Propylene glycol in the collection cups effectively preserved captured triatomines allowing for molecular detection of T. cruzi. The trapping experiments established dispersal patterns for the captured species. We conclude that multiple-funnel traps with solar-powered LED lights should be considered for adoption as surveillance and potentially mass-trapping management tools for triatomines.

Epidemiology of marine turtle fibropapillomatosis and tumour-associated chelonid alphaherpesvirus 5 (ChHV5; Scutavirus chelonidalpha5) in North-Western Mexico: a scoping review implementing the one health approach

Fibropapillomatosis (FP) - tumour-associated chelonid alphaherpesvirus 5 (ChHV5; Scutavirus chelonidalpha5) - is a disease that affect marine turtles around the world, and characterized by the formation of cutaneous tumours that can appear anywhere on the body. We carried out a thorough literature search (from 1990 to 2024) in the feeding sites of North-western Mexico, a region that hosts important habitats for feeding, development, and reproduction for five of the seven existing sea turtle species. We found 18 reports recording a total of 32 cases of FP and/or ChHV5/Scutavirus chelonidalpha5 in coastal and insular areas of North-western Mexico. Baja California Sur resulted with the highest number of cases (75%). While the first case of ChHV5/Scutavirus chelonidalpha5 infection was reported in 2004, the presence of FP tumours was reported in 2014 and became more frequent between 2019 and 2024. The affected species were black, Chelonia mydas (50%), olive ridley, Lepidochelys olivacea (46.8%) and loggerhead turtles, Caretta caretta (3.2%). Tumours occurred mainly in anterior flippers (46.1%) and neck (22.5%), and most had a nodular and verrucous appearance with a rough surface. In the study region, there is a potential sign of the emergence of the ChHV5/Scutavirus chelonidalpha5 infections and FP disease during the last 20 years, with a rapid increase during the last 10 years. As long as infections by ChHV5/Scutavirus chelonidalpha5 and the prevalence of the FP disease may be potentially influenced by anthropogenic activities, a One Health approach is needed to understand and improve sea turtles’ health.

Development and implementation of a geriatric oncology interprofessional case-based educational intervention for cancer care providers.

9020 Background: Geriatric assessment (GA) is recommended as part of the standard of care for older adults with cancer. However, the GA has not been fully adopted as part of routine practice in oncology in Mexico, mainly due to lack of qualified personnel and limited knowledge. We designed an interprofessional case-based educational intervention to address the main barriers for implementation of GA in oncology. Methods: We followed Kern’s six-step approach to design a continuing professional development (CPD) activity. Our targeted learners consisted of teams comprised of one oncologist and one geriatrician who practiced at the same site in Mexico. By the end of the intervention, participants would be able to perform GA in older adults with cancer, and to integrate information obtained through a GA in a cancer treatment plan through adequate interventions. We used Project ECHO’s model to create a CPD activity consisting of 12 weekly 75-minute online sessions via Zoom, with content selected from international geriatric oncology guidelines. At baseline, and at the end of the course, participants answered a 36-item multiple choice knowledge assessment (scale 0-100), a survey on self-perceived competence in GA skills (scale 0-10), and an adaptation of the Association for Community Cancer Centers Geriatric Oncology Gap Assessment Tool, which assesses subjective performance of the GA (scale 0-4). Participants also completed a satisfaction questionnaire. We compared baseline and post-intervention scores through paired t tests; results from the satisfaction questionnaire are reported descriptively. Results: We included 56 participants (28 geriatricians and 28 oncologists). Median participant attendance was 10 sessions (IQR 9-11). Thirty-eight participants completed the satisfaction questionnaire: median satisfaction was 10/10 (range 8-10). There was no difference in satisfaction scores between oncologists and geriatricians. Mean baseline knowledge score was 59.5±12.8 and mean post-intervention knowledge score was 74.4±9.7 (p&lt;0.001, effect size 1.14). Mean baseline competence score was 6.42±2.5 and mean post-intervention competence score was 9.02±0.78 (p&lt;0.001, effect size 1.03). Mean baseline performance score was 2.58±0.65 and mean post-intervention knowledge score was 3.29±0.5 (p&lt;0.001, effect size 1.64). Increases in knowledge, competence, and performance scores were observed both in oncologists and in geriatricians separately. Conclusions: This interprofessional curriculum on GA in oncology was feasible and acceptable, and led to significant increases in knowledge, competence, and performance among participants. Project ECHO’s case-based learning model is adequate to provide interprofessional education, which is crucial in multidisciplinary areas such as geriatric oncology.

MSAIL: Milligram-Scale Multi-Modal Sensor Platform for Monarch Butterfly Migration Tracking

Each fall, millions of monarch butterflies across the northern US and Canada migrate up to 4,000km to overwinter in specific mountain peaks in central Mexico. To track monarchs precisely and study their navigation, a monarch tracker must obtain daily localization of the butterfly as it progresses on its three-month journey. And, the tracker must perform this task while having a weight in the tens of milligrams (mg) and measuring a few millimeters (mm) in size to avoid interfering with the monarch's flight. This paper proposes mSAIL, 8 × 8 × 2.6mm and 62mg embedded system for monarch migration tracking, constructed using 8 prior custom-designed ICs providing solar energy harvesting, an ultra-low power processor, light/temperature sensors, power management, and a wireless transceiver, all integrated and 3D stacked on a micro PCB with an 8 × 8mm printed antenna. The proposed system is designed to record and compress light and temperature data during the migration path while harvesting solar energy for energy autonomy, and wirelessly transmit the data at the overwintering site in Mexico, from which the daily location of the butterfly can be estimated using a deep learning-based localization algorithm. A two-day trial experiment of mSAIL attached to a live butterfly in an outdoor botanical garden demonstrates the feasibility of individual butterfly localization and tracking.

Ontogenesis and variation of wood ‘parenchymatization’ in Cochlospermum vitifolium (Bixaceae)

Summary Axial parenchyma proliferation (non-lignified parenchyma) in wood has been characterized for only a few species. In the present study, we characterized the proliferation, ontogeny, and seasonal variation of wood axial parenchyma in Cochlospermum vitifolium (Bixaceae). This study included material from natural populations from different sites in Mexico. We analyzed the wood anatomy and development in stems of different ages, and monthly sampling of the main stem during the growing season. The results show that the wood anatomy of C. vitifolium is characterized by features associated with efficient water transport, such as wide vessels and low vessel frequency. The wood has a high storage and radial transport capacity. Axial parenchyma is abundant and constitutes the main cell type of the wood. Rays are wide and tall with a high starch content. Ontogenetic development of the wood showed that non-lignified axial parenchyma differentiates after secondary growth has been established. Parenchyma proliferation does not occur in an axially orderly fashion and the results suggest that there is a relationship between maximum proliferation and precipitation. We found high variation in wood parenchymatization between trees. The maximum parenchymatization and succulence was found in trees with larger stem diameter. The ecological and ontogenetic implications of wood parenchymatization are discussed.

Safety strategies and harm reduction for methamphetamine users in the era of fentanyl contamination: A qualitative analysis

IntroductionIn the United States, methamphetamine use is increasing and the context of its use has changed, with reports of illicitly manufactured fentanyl being mixed with methamphetamine (either deliberately or inadvertently). We explore risk-mitigating actions taken by people who use drugs to protect their health when using methamphetamine in that context. MethodsWe conducted qualitative interviews with 48 adults (18+) who used methamphetamine in the past three months at two sites in Nevada, USA and two sites in New Mexico, USA. Interviews were recorded, transcribed, and analyzed using thematic analysis. ResultsRespondents described two rationales for employing harm reduction strategies. First, to prevent harm from methamphetamine containing illicit fentanyl, and second, to maintain their general wellbeing while using methamphetamine. Regarding methamphetamine containing illicit fentanyl, our findings highlight how respondents employ primary strategies like buying from trusted sources and secondary strategies such as spotting and selective use of harm reduction tools (i.e., fentanyl test strips) to reduce risks. To maintain their general wellbeing, participants reduced their use of methamphetamine as reasonably as possible, and used other substances like marijuana and alcohol alongside methamphetamine to counter the unwanted side effects of methamphetamine (i.e., hallucinations and paranoia). Use of these harm reduction strategies varied within situational and social contexts, and respondents usually developed these strategies based on their lived experiences. ConclusionOur findings uniquely demonstrate that people who use methamphetamine prioritize community driven, trust-based strategies within their social networks to mitigate risks in a fentanyl-contaminated drug environment. Additionally, our results indicate that harm reduction behaviors are influenced by multilevel risk environments, which include social, physical, economic, and political factors. Overall, these results highlight the potential for targeted interventions at the network level, which are responsive to complexities and shifts in drug market dynamics- such as illicit fentanyl in methamphetamine.

Ecology shapes the genomic and biosynthetic diversification of Streptomyces bacteria from insectivorous bats.

Streptomyces are prolific producers of secondary metabolites from which many clinically useful compounds have been derived. They inhabit diverse habitats but have rarely been reported in vertebrates. Here, we aim to determine to what extent the ecological source (bat host species and cave sites) influence the genomic and biosynthetic diversity of Streptomyces bacteria. We analysed draft genomes of 132 Streptomyces isolates sampled from 11 species of insectivorous bats from six cave sites in Arizona and New Mexico, USA. We delineated 55 species based on the genome-wide average nucleotide identity and core genome phylogenetic tree. Streptomyces isolates that colonize the same bat species or inhabit the same site exhibit greater overall genomic similarity than they do with Streptomyces from other bat species or sites. However, when considering biosynthetic gene clusters (BGCs) alone, BGC distribution is not structured by the ecological or geographical source of the Streptomyces that carry them. Each genome carried between 19-65 BGCs (median=42.5) and varied even among members of the same Streptomyces species. Nine major classes of BGCs were detected in ten of the 11 bat species and in all sites: terpene, non-ribosomal peptide synthetase, polyketide synthase, siderophore, RiPP-like, butyrolactone, lanthipeptide, ectoine, melanin. Finally, Streptomyces genomes carry multiple hybrid BGCs consisting of signature domains from two to seven distinct BGC classes. Taken together, our results bring critical insights to understanding Streptomyces-bat ecology and BGC diversity that may contribute to bat health and in augmenting current efforts in natural product discovery, especially from underexplored or overlooked environments.

Arsenic and mercury exposure in different insect trophic guilds from mercury mining areas in Mexico.

The exposure to arsenic and mercury in various insect trophic guilds from two mercury mining sites in Mexico was assessed. The two study sites were La Laja (LL) and La Soledad (LS) mines. Additionally, a reference site (LSR) was evaluated for LS. The terrestrial ecosystem was studied at LL, whereas both the terrestrial ecosystem and a stream called El Cedral (EC) were assessed at LS. The study sites are situated in the Biosphere Reserve Sierra Gorda (BRSG). Mercury vapor concentrations were measured with a portable analyzer, and concentrations of arsenic and mercury in environmental and biological samples were determined through atomic absorption spectrophotometry. Both pollutants were detected in all terrestrial ecosystem components (soil, air, leaves, flowers, and insects) from the two mines. The insect trophic guilds exposed included pollinivores, rhizophages, predators, coprophages, and necrophages. In LS, insects accumulated arsenic at levels 29 to 80 times higher than those found in specimens from LSR, and 10 to 46 times higher than those from LL. Similarly, mercury exposure in LS was 13 to 62 times higher than LSR, and 15 to 54 times higher than in LL. The analysis of insect exposure routes indicated potential exposure through air, soil, leaves, flowers, animal prey, carrion, and excrement. Water and sediment from EC exhibited high levels of arsenic and mercury compared to reference values, and predatory aquatic insects were exposed to both pollutants. In conclusion, insects from mercury mining sites in the BRSG are at risk.

Species composition of two communities of Mexican crane flies (Diptera: Tipulomorpha: Tipuloidea) separated by a geographic barrier, with additional notes and new records

ABSTRACT The presence or absence of species in a specific area and their distribution in geographic space are consequences of various factors, including geographic barriers. This study analyzes the change in species composition of two crane fly communities separated by a geographic barrier in the state of Veracruz, Mexico. Crane flies were collected using Malaise traps in 10 sites across two transects along the Misantla river (MT) and Actopan river (AT) basins, divided by the Chiconquiaco mountain range, through quarterly samplings over three years. A total of 559 specimens belonging to 60 species were collected, with 45 in MT (23 exclusive) and 37 species in AT (15 exclusive). The species composition differed by more than 60% between transects, primarily due to turnover; with higher values and a similar pattern among the sites along the transects, it is suggested that geographic barrier could be a factor in the change in composition. Additionally, three new and 41 potential new records for Mexico and 10 new records for Veracruz are reported, increasing the species records in Veracruz to 90 and in the country to 376. This study represents the first assessment of crane flies species composition at a specific site in Mexico.

Nitrogen compounds at Mexican and USA coasts on the Gulf of Mexico

In recent decades, anthropogenic emissions in the Gulf of Mexico have caused a deterioration in air quality in surrounding areas, mainly due to particulate matter, sulfur dioxide and nitrogen dioxide. Over this period, interest in reactive nitrogen compounds has increased due to their relationships to air quality and ecosystem impacts associated with atmospheric deposition. In this study we summarize air concentrations of nitrogen dioxide in ambient air and wet atmospheric deposition of nitrate and ammonium along the southern coast of the United States of America and eastern Mexico over the period 2017 to 2020. The highest concentrations of ammonium and nitrate were observed in precipitation at Texas and sites in Mexico, although the highest rates of atmospheric deposition were observed in Florida and Louisiana. The ratio between ammonium and nitrate in precipitation was higher at Mexican stations than in studied sites in the United States, influenced by meteorological factors, atmospheric emissions, and characteristic air mass transport in the region. Back trajectory modeling showed the importance of the seasonality of the wind in the transport of nitrogen compounds of local and regional origin that affect Veracruz.

Rickettsia species identified in adult, host-seeking Dermacentor occidentalis (Acari: Ixodidae) from Baja California, Mexico, and Oregon and Washington, United States.

The Pacific Coast tick (Dermacentor occidentalis Marx, 1892) is a frequently encountered and commonly reported human-biting tick species that has been recorded from most of California and parts of southwestern Oregon, southcentral Washington, and northwestern Mexico. Although previous investigators have surveyed populations of D. occidentalis for the presence of Rickettsia species across several regions of California, populations of this tick have not been surveyed heretofore for rickettsiae from Baja California, Oregon, or Washington. We evaluated 1,367 host-seeking, D. occidentalis adults collected from 2015 to 2022 by flagging vegetation at multiple sites in Baja California, Mexico, and Oregon and Washington, United States, using genus- and species-specific assays for spotted fever group rickettsiae. DNA of Rickettsia 364D, R. bellii, and R. tillamookensis was not detected in specimens from these regions. DNA of R. rhipicephali was detected in D. occidentalis specimens obtained from Ensenada Municipality in Baja California and southwestern Oregon, but not from Washington. All ompA sequences of R. rhipichephali that were amplified from individual ticks in southwestern Oregon were represented by a single genotype. DNA of the Ixodes pacificus rickettsial endosymbiont was amplified from specimens collected in southwestern Oregon and Klickitat County, Washington; to the best of our knowledge, this Rickettsia species has never been identified in D. occidentalis. Collectively, these data are consistent with a relatively recent introduction of Pacific Coast ticks in the northernmost extension of its recognized range.

Review: The First Atomic Bomb: The Trinity Site in New Mexico, by Janet Farrell Brodie

Review: <i>The First Atomic Bomb: The Trinity Site in New Mexico</i>, by Janet Farrell Brodie

Shallow three-dimensional shear wave velocity model for the Mexico City Basin

In this study, a simplified shallow three-dimensional shear wave velocity (Vs) model is presented for the Mexico City Basin. To this end, previous studies were carefully reviewed to assemble a database of Vs and site period measurements for the region. The new site period measurements obtained at the western edge of the Basin were compared to the existing 2004 Complementary Technical Standards of Mexico site period nominal map, (NTC, 2004) the Lermo et al. (2020) site period map, and Design Seismic Actions System (SASID), 2020 site period predictions. Each site period prediction method was shown to have differences with respect to the new measurements along the western edge of the Basin. However, there was no bias for the prediction methods with the Lermo et al. (2020) and SASID predictions, demonstrating less error between the measured values than the NTC (2004) predictions. To develop the three-dimensional Vs model, the shallow (top 60 m) subsurface was divided into five generalized soil layers. The site period was used as the only input for the three-dimensional Vs model to simplify and maximize the model’s applicability. The performance of the model was assessed by comparing the measured and predicted Vs profiles. Overall, the three-dimensional Vs model developed in this study is a valuable tool that can be used along with geophysical estimates of deeper structure for ground motion modeling and preliminary site response studies along with other benefits to the seismic resiliency of the region.