Southwestern US Research Articles

Seismic Modeling of Bedload Transport in a Gravel‐Bed Alluvial Channel

AbstractRecent theoretical models and field observations suggest that fluvial bedload flux can be estimated from seismic energy measured within appropriate frequency bands. We present an application of the Tsai et al. (2012, https://doi.org/10.1029/2011gl050255) bedload seismic model to an ephemeral channel located in the semi‐arid southwestern US and incorporate modifications to better estimate bedload flux in this environment. To test the model, we collected streambank seismic signals and directly measured bedload flux during four flash‐floods. Bedload predictions calculated by inversion from the Tsai model underestimated bedload flux observations by one‐to‐two orders of magnitude at low stages. However, model predictions were better for moderate flow depths (>50 cm), where saltation is expected to dominate bedload transport. We explored three differences between the model assumptions and our field conditions: (a) rolling and sliding particles have different impact frequencies than saltating particles; (b) the velocity and angle of impact of rolling particles onto the riverbed differ; and (c) the fine‐grained alluvial character of this and similar riverbeds leads to inelastic impacts, as opposed to the originally conceptualized elastic impacts onto rigid bedrock. We modified the original model to assume inelastic bed impacts and to incorporate rolling and sliding by adjusting the statistical distributions of bedload impact frequency, velocity, and angle. Our modified “multiple‐transport‐mode bedload seismic model” decreased error relative to observations to less than one order of magnitude across all measured flow conditions. Further investigations in other environmental settings are required to demonstrate the robustness and general applicability of the model.

Gestational exposure to wildfire PM2.5 and its specific components and the risk of gestational hypertension and eclampsia in the southwestern United States

In the southwestern United States, the frequency of summer wildfires has elevated ambient PM2.5 concentrations and rates of adverse birth outcomes. Notably, hypertensive disorders in pregnancy (HDP) constitute a significant determinant associated with maternal mortality and adverse birth outcomes. Despite the accumulating body of evidence, scant research has delved into the correlation between chemical components of wildfire PM2.5 and the risk of HDP. Derived from data provided by the National Center for Health Statistics, singleton births from >2.68 million pregnant women were selected across 8 states (Arizona, AZ; California, CA, Idaho, ID, Montana, MT; Nevada, NV; Oregon, OR; Utah, UT, and Wyoming, WY) in the southwestern US from 2001 to 2004. A spatiotemporal model and a Goddard Earth Observing System chemical transport model were employed to forecast daily concentrations of total and wildfire PM2.5-derived exposure. Various modeling techniques including unadjusted analyses, covariate-adjusted models, propensity-score matching, and double robust typical logit models were applied to assess the relationship between wildfire PM2.5 exposure and gestational hypertension and eclampsia. Exposure to fire PM2.5, fire-sourced black carbon (BC) and organic carbon (OC) were associated with an augmented risk of gestational hypertension (ORPM2.5 = 1.125, 95 % CI: 1.109,1.141; ORBC = 1.247, 95 % CI: 1.214,1.281; OROC = 1.153, 95 % CI: 1.132, 1.174) and eclampsia (ORPM2.5 = 1.217, 95 % CI: 1.145,1.293; ORBC = 1.458, 95 % CI: 1.291,1.646; OROC = 1.309, 95 % CI: 1.208,1.418) during the pregnancy exposure window with the strongest effect. The associations were stronger that the observed effects of ambient PM2.5 in which the sources primarily came from urban emissions. Social vulnerability index (SVI), education years, pre-pregnancy diabetes, and hypertension acted as effect modifiers. Gestational exposure to wildfire PM2.5 and specific chemical components (BC and OC) increased gestational hypertension and eclampsia risk in the southwestern United States.

"I Was Treated Differently": Reproductive Health Care Experiences Among Women With Recent Experiences of Incarceration, Homelessness, And/Or Substance Use in a Medically Underserved Area in the Southwestern US.

Background: Women with upstream social determinants of health, particularly those with recent experiences of incarceration, homelessness, and/or substance use, encounter a series of barriers in accessing health care services and consequently face poor sexual and reproductive health outcomes. Driven by a community concern for increasing rates of syphilis and congenital syphilis among women who are structurally disadvantaged, this study focuses on their experiences with reproductive healthcare access across healthcare settings.Research Design and Study Sample: This community-basedpláticas(conversational) research project gathered 12 in-depth interviews andtestimonios(testimonies) with women who reported a criminalized upstream barrier (incarceration, homelessness, and/or substance use) in a small city in the southwestern U.S.-most of whom identified as Latina/Hispanic.Analysis and Results: Using a grounded analysis and drawing upon Chicana feminist methodologies, this study identifies four major themes: (1) homelessness and economic vulnerabilities, (2) incarceration and health care, (3) drug use, provider stigma, and motherhood, and (4) desired changes to the healthcare experience.Conclusion: Results highlight the need for economic and transportation supports, community-based preventive services as alternatives to incarcerated healthcare, along with more compassionate and structurally competent provider-patient dialogue.

The Mayo Leadership Impact Index Adapted for Matrix Leadership Structures: Initial Validity Evidence.

Physician burnout has reached crisis levels. Supportive leadership is one of the strongest drivers of physician well-being, and monitoring supervisor support is key to developing well-being focused leadership skills. Existing measures of leader support were designed within "direct report" supervision structures limiting their applicability to matrixed leadership reporting structures where direct reports are not the predominant norm. Antecedently, no measure of leadership support is validated specifically for implementation in matrixed leadership structures. Adapt and validate the Mayo Leadership Impact Index (MLII) for settings with matrixed leadership structures. A psychometric validation study utilizing classical test theory and item response theory. A tripartite hospital system in the southwestern US. Physician-respondents to a 2023 cross-sectional survey. After pilot testing, the adapted MLII was examined using a unidimensional graded response model and confirmatory factor analyses. Convergent validity was investigated via correlations with professional fulfillment, perceived autonomy support, self-valuation, and peer connectedness/respect. Divergent validity was tested via correlations with burnout. Of the three candidate revisions of the MLII, the 9-item adaptation was selected for its superior validity/reliability indices. Standardized Cronbach's and Ordinal alpha coefficients were 0.958 and 0.973, respectively. CFA loadings exceeded 0.70 (p < 0.001), and coefficients of variation (R2) exceeded 0.60 for all items. GRM slope parameters indicated "high" to "very high" item discrimination. Items 2, 5, and 8 were the most informative. Positive correlations of the adapted MLII with professional fulfillment, perceived autonomy support, and peer connectedness/respect were observed, supporting convergent validity. Negative correlation with overall burnout supports divergent validity. The findings provide evidence of the adapted MLII's validity, reliability, and appropriateness for implementation within matrixed leadership settings. Prior to this study, no leadership support measure had been validated for use among the growing number of healthcare systems with matrixed leadership reporting structures.

Potential for spatial coexistence of a transboundary migratory species and wind energy development

Global expansion in wind energy development is a notable achievement of the international community’s effort to reduce carbon emissions during energy production. However, the increasing number of wind turbines have unintended consequences for migratory birds and bats. Wind turbine curtailment and other mitigation strategies can reduce fatalities, but improved spatial and temporal data are needed to identify the most effective way for wind energy development and volant migratory species to coexist. Mexican free-tailed bats (Tadarida brasiliensis mexicana) account for a large proportion of known bat fatalities at wind facilities in the southwestern US. We examined the geographic concordance between existing wind energy generation facilities, areas of high wind potential amenable for future deployment of wind facilities, and seasonally suitable habitat for these bats. We used ecological niche modeling to determine species distribution during each of 4 seasons. We used a multi-criteria GIS-based approach to produce a wind turbine siting suitability map. We identified seasonal locations with highest and lowest potential for the species’ probability of occurrence, providing a potential explanation for the higher observed fatalities during fall migration. Thirty percent of 33,606 wind turbines within the southwestern US occurred in highly suitable areas for Mexican free-tailed bats, primarily in west Texas. There is also broad spatial overlap between areas of high wind potential and areas of suitable habitat for Mexican free-tailed bats. Because of this high degree of overlap, our results indicate that post-construction strategies, such as curtailing the timing of operations and deterrents, would be more effective for bat conservation than strategic siting of new wind energy installations.

What is a migrant death? An operational definition for a more accurate enumeration of migrant mortality along the US-Mexico border

Over the last forty years an indeterminate number of persons, ranging from thousands to tens of thousands, have died along the US-Mexico border during migration, fleeing poverty, armed conflict, situations of violence, and disasters. An accurate accounting of migrant deaths along the southern US border is the first step toward an understanding of the extent and the contributing factors of these deaths. In this article, we describe a key aspect of our collaborative work aimed at developing a more representative account of migrant mortality along the southwestern US border: the determination of criteria for inclusion of specific forensic cases as “migrant.” Our intention is not to propose a definition of “what is a migrant death” applicable to all contexts and situations but rather one specific to the US-Mexico border region. Our main impetus is to build and launch a web portal to track and map migrant deaths at the US-Mexico border. The criteria we have identified are based on an examination of death data collected by various agencies in the four border states (California, Arizona, New Mexico, and Texas) and at the federal level by the National Missing and Unidentified Persons System (NamUs). They include a) context of human remains discovery; b) identification media/documentation; c) geographic setting; and d) personal effects. Taken together, these criteria will facilitate our determination, case by case, of the probability that human remains found along the United States side of the border may be from a person in the context of migration.

Dust storms and cardiorespiratory emergency department visits in three Southwestern United States: application of a monitoring-based exposure metric

Climate change is projected to increase the risk of dust storms, particularly in subtropical dryland, including the southwestern US. Research on dust storm’s health impacts in the US is limited and hindered by challenges in dust storm identification. This study assesses the potential link between dust storms and cardiorespiratory emergency department (ED) visits in the southwestern US. We acquired data for 2005–2016 from eight IMPROVE (Interagency Monitoring of PROtected Visual Environments) sites in Arizona, California, and Utah. We applied a validated algorithm to identify dust storm days at each site. We acquired patient-level ED visit data from state agencies and ascertained visits for respiratory, cardiovascular, and cause-specific subgroups among patients residing in ZIP codes within 50 km of an IMPROVE site. Using a case-crossover design, we estimated short-term associations of ED visits and dust storms, controlling for temporally varying covariates. During 2005–2016, 40 dust storm days occurred at the eight IMPROVE sites. Mean PM10 and PM2.5 levels were three to six times greater on dust storm days compared to non-dust storm days. Over the study period, there were 2 524 259 respiratory and 2 805 925 cardiovascular ED visits. At lags of 1, 2, and 3 days after a dust storm, we observed 3.7% (95% CI: 1.0%, 7.6%), 4.9% (95% CI: 1.1%, 8.9%), and 5.0% (95% CI: 1.3%, 8.9%) elevated odds of respiratory ED visits compared to non-dust storm days. Estimated associations of dust storm days and cardiovascular disease ED visits were largely consistent with the null. Using a monitoring-based exposure metric, we observed associations among dust storms and respiratory ED visits. The results add to growing evidence of the health threat posed by dust storms. The dust storm metric was limited by lack of daily data; future research should consider information from satellite and numerical models to enhance dust storm characterization.

Promoting clean energy in the Navajo nation

Promoting clean energy in the Navajo nation University President Elmer Guy examines the vital role of educational institutions like Navajo Technical University in empowering communities and supporting their efforts to achieve clean energy development goals. The Navajo Nation encompasses more than 25,000 square miles of desert and scrubland in the southwestern US. The Navajo People, or Diné as they refer to themselves, have long advocated for self-determination. Through the Navajo Technical University (NTU), the Navajo community has the ability to educate its youth in line with its traditions, cultures, and beliefs. However, the lack of Navajo engineering faculty results in a scarcity of role models for engineering students.

Restoring frequent fire to dry conifer forests delays the decline of subalpine forests in the southwest United States under projected climate

Abstract In southwestern US forests, the combined impact of climate change and increased fuel loads due to more than a century of human‐caused fire exclusion is leading to larger and more severe wildfires. Restoring frequent fire to dry conifer forests can mitigate high‐severity fire risk, but the effects of these treatments on the vegetation composition and structure under projected climate change remain uncertain. We used a forest landscape model to assess the impact of thinning and prescribed burns in dry conifer forests across an elevation gradient, encompassing low‐elevation pinyon‐juniper woodlands, mid‐elevation ponderosa pine and high‐elevation mixed‐conifer forests. Our results demonstrated that the treatments decreased the probability of high‐severity fires by 42% in the study area. At low elevation, the treatments did not prevent loss in forest cover and biomass with decreases in Pinus edulis and Juniperus monosperma abundances. At mid‐elevation, changes in fire effects maintained a greater diversity of tree species by favouring the maintenance of cohorts of old trees, in particular Pinus ponderosa which accumulated 5.41 Mg ha−1 more above‐ground biomass than without treatments by late‐century. Treatments in dry conifer forests modified fire effects beyond the treated area, resulting in increased cover and biomass of old Picea englemannii and Abies lasiocarpa cohorts. Synthesis and applications: Our findings indicate that thinning and prescribed burning can enhance tree species diversity in dry conifer forests by protecting old cohorts from stand‐replacing fires. Moreover, our results suggest that treatments mainly implemented in dry pine forests with high risk of high‐severity fires can be beneficial for subalpine species conservation by reducing the chance that high‐severity fire at mid‐elevation is transmitted into high‐elevation forest.

Forest Treatment Effects on Watershed Responses Under Warming

AbstractThe effects of forest treatments on watershed hydrology have often been studied in isolation from climate change. Consequently, under a warming climate, it is unclear how forest thinning will impact snowpacks, evapotranspiration, and streamflow availability. In this study, we used a distributed hydrologic model to provide insight into the effects of warming and forest treatment on the hydrologic response of the Beaver Creek watershed (∼1,100 km2) of central Arizona. Prior to the numerical experiments, confidence in the hydrologic model performance was established by comparisons to long‐term observations (2003–2018) of snow water equivalent and streamflow using station observations and through spatially distributed estimates. Results indicated that warming during the 21st century could increase mean annual streamflow by 1.5% for warming levels up to +1°C, followed by a −29% decrease for continued warming up to +6°C, due to the varying effects of warming on snow sublimation, soil evaporation, and plant transpiration. On average, forest thinning increased streamflow by +12% (or 7 mm/yr) through lower plant transpiration by −19% (or −18 mm/yr), while also increasing the change in soil water storage by +42% (or 11 mm/yr). Forest thinning delayed the detrimental effects of warming on streamflow until +4°C, as compared to +2°C without forest treatment. Furthermore, model results suggested that forest cover reductions laterally displace water availability and evapotranspiration to downstream sites. These model‐derived mechanisms provide insights on the potential for water resilience toward warming effects afforded through treatment projects in southwestern US ponderosa pine forests.

Sustainability Requires Many Faces of Support

ABSTRACT Purpose: This study focused on the sustainability of a school-wide health behavior intervention in rural schools in the Southwestern US. Informed by the seven premises of Theories of Action with Merit, the purpose of this study was to investigate which portion(s) of a five-year, school-wide health behavior intervention were still in practice (i.e. sustainable), and why they were maintained following the removal of funding and resources for the program. Method: Teachers (N = 41) participated in individual, semi-structured interviews during which they shared what aspects of the original intervention were retained as part of personal classroom practices or of the school culture. Teachers reflected on facilitators and barriers to the sustainability of these practices. Data also included field notes from campus visits. To establish trustworthiness, data triangulation (interview transcripts, survey results, and field notes) provided multiple angles of analysis, and two researchers negotiated all themes. Results: Using the premises of the Theories of Action with Merit, teachers’ comments often circulated around themes of administrative support and personal investment/interest in healthy behaviors. Additional themes of sustainability included feeling capable and physical activity being the “norm” at their school. Conclusions: Teachers’ personal beliefs and self-efficacy in physical literacy held the highest importance in sustaining classroom healthy behavior practices as opposed to the district or state expectations for healthy behaviors. Administrator support was key to whole-school integration and sustainability of practices, however, teachers described evidence of support differently suggesting administrators need awareness of how messages of support are being translated.

The emergence of Rocky Mountain spotted fever in the southwestern United States and northern Mexico requires a binational One Health approach.

Rocky Mountain spotted fever (RMSF) is an international and quintessential One Health problem. This paper synthesizes recent knowledge in One Health, binational RMSF concerns, and veterinary and human medical perspectives to this fatal, reemerging problem. RMSF, a life-threatening tick-borne disease caused by the bacterium Rickettsia rickettsii, emerged during the first decade of the 21st century in impoverished communities in the southwestern US and northern Mexico. Lack of an index of suspicion, delay in diagnosis, and delayed initiation of antibiotic treatment contribute to fatality. Campaigns targeting dog neutering, restraint to residents' properties, and on-dog and on-premises treatment with acaricides temporarily reduce prevalence but are often untenable economically. Contemporary Mexican RMSF is hyperendemic in small communities and cities, whereas epidemics occur in the western US primarily in small tribal communities. In in both locations, the epidemics are fueled by free-roaming dogs and massive brown dog tick populations. In the US, RMSF has a case fatality rate of 5% to 7%; among thousands of annual cases in Mexico, case fatality often exceeds 30%.1,2 Numerous case patients in US border states have recent travel histories to northern Mexico. Veterinarians and physicians should alert the public to RMSF risk, methods of prevention, and the importance of urgent treatment with doxycycline if symptomatic. One Health professionals contribute ideas to manage ticks and rickettsial disease and provide broad education for the public and medical professionals. Novel management approaches include vaccine development and deployment, acaricide resistance monitoring, and modeling to guide targeted dog population management and other interventions.

Coccidioidomycosis in Oklahoma: A retrospective case series.

Coccidioidomycosis is a systemic fungal disease endemic to arid regions of the Western Hemisphere. In the south-western US, Coccidioides spp. may account for up to 20%-25% of all cases of community acquired pneumonia. Clinical manifestations vary widely, from asymptomatic infection to life-threatening disease, especially in immunocompromised hosts. The primary objective of the study was to characterise cases of coccidioidomycosis in an area of the United States not considered traditionally endemic for the disease. We performed a single-centre retrospective study of all cases of coccidioidomycosis from 1 January 2000 to 31 December 2020, in the University of Oklahoma Health Sciences Medical Center. A total of 26 patients were included for analysis. The central nervous system (CNS) and the lungs were the sites most frequently involved. Twenty (77%) had travelled to a coccidioidomycosis endemic region. Most were male (81%) with a median age of 42 years (range: 3-78 years). The majority (46%) were Caucasians, 19% were African American, 19% Hispanic, and 12% Native American. The most common comorbidities were diabetes mellitus and acquired immunodeficiency syndrome, identified in 27% and 23% of patients, respectively. Patients on immunosuppressive therapy accounted for 12% of all cases. Our study is one of the largest single-centre case series of coccidioidomycosis from a non-endemic area. Diabetes mellitus was the most frequent comorbidity. Compared to other case series of coccidioidomycosis, our patient population had higher rates of immunosuppression and had both a higher rate of disseminated disease and overall mortality.

Relationship Between Primary Care Physician Capacity and Usual Source of Care.

The NASEM Primary Care Report and Primary Care scorecard highlighted the importance of primary care physician (PCP) capacity and having a usual source of care (USC). However, research has found that PCP capacity and USC do not always correlate. This exploratory study compares geographic patterns and the characteristics of counties with similar rates of PCP capacity but varying rates of USC. Our county-level, cross-sectional approach includes estimates from the Robert Graham Center and data from the Robert Wood Johnson County Health Rankings (CHR). We utilized conditional mapping methods to first identify US counties with the highest rates of social deprivation (SDI). Next, counties were stratified based on primary care physician (PCP) capacity and usual source of care (USC) terciles, allowing us to identify 4 types of counties: (1) High-Low (high PCP capacity, low USC); (2) High-High (high PCP capacity, high USC); (3) Low-High (low PCP capacity, high USC); and (4) Low-Low (low PCP capacity, low USC). We use t test to explore differences in the characteristics of counties with similar rates of primary care capacity. The results show clear geographic patterns: High-High counties are located primarily in the northern and northeastern US; High-Low counties are located primarily in the southwestern and southern US. Low-High counties are concentrated in the Appalachian and Great Lakes regions; Low-Low counties are concentrated in the southeastern US and Texas. Descriptive results reveal that rates of racial and ethnic minorities, the uninsured, and social deprivation are highest in counties with low rates of USC for both high PCP and low PCP areas. Recognizing PCP shortages and improving rates of USC are key strategies for increasing access to high-quality, primary care. Targeting strategies by geographic region will allow for tailored models to improve access to and continuity of primary care. For example, we found that many of the counties with the lowest rates of USC are found in non-Medicaid expansion states (Texas, Georgia, and Florida) with high rates of uninsured populations, suggesting that expanding Medicaid and improving access to health insurance are key strategies for increasing USC in these states.

Reducing energy and carbon footprint in semi-arid irrigated cropping systems through crop diversification

Energy and carbon (C) footprints of agricultural production practices have garnered high attention due to rising energy costs and increasing global warming. However, the contribution of conservation and regenerative farming practices, including cover cropping, on energy and C footprints have not yet been documented for cropping systems in arid and semi-arid regions. This study evaluated the energy and C footprint of cover crop integrated silage maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) production systems in the semi-arid region of the southwestern US. The treatments were mixtures of winter cover crops: i) grasses and legumes (GL), ii) grasses, brassicas, and legumes (GBL), iii) grasses and brassicas (GB), and iv) no cover crops (NCC) control for each crop production system. Results showed cover crops had 24.1–24.5% greater energy input than NCC. In silage maize rotation, energy output was 17–22% greater in GBL and GL than in NCC. In silage sorghum rotation, the energy output was 15–24% greater in all cover crops than in NCC. The resulting net energy was 16–21% greater in GBL and GL than in NCC under silage maize, while it was 18–24% greater in GBL and GB than in NCC under silage sorghum. In the silage maize system, the C-footprint per kg yield was not different among treatments, whereas in silage sorghum, it was 58% greater in GBL than in NCC. The benefit-to-cost ratio was greater than one for all treatments, but the additional revenue through C credit programs could make cover cropping a more feasible and beneficial approach, improving economic and environmental sustainability while producing silage crops. While the C footprint was crop rotation specific, cover cropping should be encouraged over crop-fallow systems to producers in semi-arid environments to reduce energy usage and increase C-credit benefits. Clear national and state policy on the C credit program will also enhance economic and environmental benefits by adopting cover cropping and other regenerative farming practices.

Comparing the impact of the Sport Education model on student motivation in Kuwaiti and American students.

Sport Education (SE) stands as the most researched pedagogical model in physical education. While researchers have consistently underscored its capacity to improve student motivation in physical education, a gap remains concerning its implications in Arab nations. Moreover, no studies have been identified comparing the outcomes of SE between the U.S., where the model originated, and other countries. This study was conducted to (1) determine the impact of SE on Kuwaiti students' motivation, (2) determine any differential effects of SE on Kuwaiti and American students' motivation, and (3) explore students' perceptions of SE in both countries. A replicated mixed methods quasi-experimental pre-test and post-test design was used. Participants were 33 secondary school students (nine girls and 24 boys; ages 11-12) from two classes in southwestern US, and 37 secondary school students (12 girls and 25 boys; ages 10-11) from two classes in Kuwait. Both sets of classes across the two countries were instructed by the same teacher who was trained in teaching SE. Student interest/enjoyment, perceived competence, effort/importance, and pressure/tension were measured using the Intrinsic Motivation Inventory instrument (IMI). Student perceptions of SE were assessed using a group Semi-structured interview. Quantitative data were analyzed using repeated measures and mixed ANOVAs followed by t-tests. Qualitative data were analyzed using a thematic analysis technique. Kuwaiti students' perceived interest/enjoyment, perceived competence, effort/importance, and pressure/tension scores significantly improved in the group that taught using SE only. Comparing the impact of the SE on students' motivation between the two countries showed no significant differences. The interview data reflected further support for the IMI results. SE can be effective in increasing Kuwaiti students' motivation in physical education. This motivating effect of SE was observed consistently across both Kuwaiti and American students.

Estimating the influence of field inventory sampling intensity on forest landscape model performance for determining high-severity wildfire risk

Historically, fire has been essential in Southwestern US forests. However, a century of fire-exclusion and changing climate created forests which are more susceptible to uncharacteristically severe wildfires. Forest managers use a combination of thinning and prescribed burning to reduce forest density to help mitigate the risk of high-severity fires. These treatments are laborious and expensive, therefore optimizing their impact is crucial. Landscape simulation models can be useful in identifying high risk areas and assessing treatment effects, but uncertainties in these models can limit their utility in decision making. In this study we examined underlying uncertainties in the initial vegetation layer by leveraging a previous study from the Santa Fe fireshed and using new inventory plots from 111 stands to interpolate the initial forest conditions. We found that more inventory plots resulted in a different geographic distribution and wider range of the modelled biomass. This changed the location of areas with high probability of high-severity fires, shifting the optimal location for management. The increased range of biomass variability from using a larger number of plots to interpolate the initial vegetation layer also influenced ecosystem carbon dynamics, resulting in simulated forest conditions that had higher rates of carbon uptake. We conclude that the initial forest layer significantly affects fire and carbon dynamics and is dependent on both number of plots, and sufficient representation of the range of forest types and biomass density.

Large-scale photovoltaic solar farms in the Sahara affect solar power generation potential globally

Globally, solar projects are being rapidly built or planned, particularly in high solar potential regions with high energy demand. However, their energy generation potential is highly related to the weather condition. Here we use state-of-the-art Earth system model simulations to investigate how large photovoltaic solar farms in the Sahara Desert could impact the global cloud cover and solar generation potential through disturbed atmospheric teleconnections. The results indicate negative impacts on solar potential in North Africa (locally), Middle East, Southern Europe, India, Eastern China, Japan, Eastern Australia, and Southwestern US, and positive impacts in Central and South America, the Caribbean, Central & Eastern US, Scandinavia and South Africa, reaching a magnitude of ±5% in remote regions seasonally. Diagnostics suggest that large-scale atmospheric circulation changes are responsible for the global impacts. International cooperation is essential to mitigate the potential risks of future large-scale solar projects in drylands, which could impact energy production.

THE JOINT EFFECTS OF PAIN AND ELEVATED DEPRESSIVE SYMPTOMS AMONG MEXICAN AMERICANS AGED 80 AND OLDER

Abstract Pain and depression are common among older Hispanic adults and their combined effects may increase mortality. We examined the joint effects of pain and depressive symptoms on mortality. We used data from the Hispanic Established Population for the Epidemiologic Study of the Elderly (2010-2016), which included Mexican Americans aged 80 and older in the Southwestern US. Participants were categorized into four groups based on self-reported pain on weight-bearing and depressive symptoms: no pain or elevated depressive symptoms, pain only, elevated depressive symptoms only, or both pain and elevated depressive symptoms. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression scale. A score of 16 or more was considered elevated depressive symptoms. Cox proportional hazards models were used to estimate the joint relationship of pain and depressive symptoms with mortality. We examined social support as a potential effect modifier. At baseline, 35.9% reported pain only, 8.6% of participants reported elevated depressive symptoms only, and 16.9% reported pain and elevated depressive symptoms (n=836). Over 6 years of follow-up, 46.2% of the sample died. Those with pain and elevated depressive symptoms had 1.41 times the risk of mortality compared to those without pain or elevated depressive symptoms (95% confidence interval: 1.05, 1.09). Having pain or elevated depressive symptoms only was not significantly associated with mortality. Social support was not a significant effect modifier. Our findings highlight the importance of screening for pain and elevated depressive symptoms among older Mexican Americans.

Climate Change Habitat Model Forecasts for Eight Owl Species in the Southwestern US.

The high-resolution forecasting of vegetation type shifts may prove essential in anticipating and mitigating the impacts of future climate change on bird populations. Here, we used the US Forest Service Ecological Response Unit (ERU) classification to develop and assess vegetation-based breeding habitat profiles for eight owl species occurring in the foothills and mountains of the Southwestern US. Shifts in mapped habitat were forecast using an ecosystem vulnerability model based on the pre-1990 climate envelopes of ERUs and the Intergovernmental Panel on Climate Change's (IPCC) A1B moderate-emission scenario for the future climate. For five of the eight owl species, the regional breeding habitat extent was projected to decline by at least 60% by 2090. Three species, the boreal owl (Aegolius funereus; at the trailing edge of its distribution), flammulated owl (Psiloscops flammeolus), and northern pygmy-owl (Glaucidium gnoma), were projected to experience the steepest habitat loss rates of 85%, 85%, and 76%, respectively. Projected vegetation shifts overlaid with well-documented flammulated owl breeding populations showed the complete or near complete loss of habitat by 2090 in areas of montane forest currently supporting dense aggregations of owl territories. Generalist or lower-elevation owl species were predicted to be less impacted, while, for the whiskered screech-owl (Megascops trichopsis), the contraction of the current habitat was nearly offset by a projected northward expansion. In general, the results of this study suggest high exposure to climate change impacts for the upper-elevation forest owls of semi-arid Southwestern North America. Long-distance migration and low natal philopatry may prove important to some montane owl populations in adapting to the regional loss of habitat.