Hippocampal volume and volume asymmetry prospectively predict PTSD symptom emergence among Iraq-deployed soldiers.

BACKGROUND: Evidence suggests a link between smaller hippocampal volume (HV) and post-traumatic stress disorder (PTSD). However, there has been little prospective research testing this question directly and it remains unclear whether smaller HV confers risk or is a consequence of traumatization and PTSD. METHODS: U.S. soldiers (N = 107) completed a battery of clinical assessments, including structural magnetic resonance imaging pre-deployment. Once deployed they completed monthly assessments of traumatic-stressors and symptoms. We hypothesized that smaller HV would potentiate the effects of traumatic stressors on PTSD symptoms in theater. Analyses evaluated whether total HV, lateral (right v. left) HV, or HV asymmetry (right - left) moderated the effects of stressor-exposure during deployment on PTSD symptoms. RESULTS: Findings revealed no interaction between total HV and average monthly traumatic-stressors on PTSD symptoms b = -0.028, p = 0.681 [95% confidence interval (CI) -0.167 to 0.100]. However, in the context of greater exposure to average monthly traumatic stressors, greater right HV was associated with fewer PTSD symptoms b = -0.467, p = 0.023 (95% CI -0.786 to -0.013), whereas greater left HV was unexpectedly associated with greater PTSD symptoms b = 0.435, p = 0.024 (95% CI 0.028-0.715). CONCLUSIONS: Our findings highlight the importance of considering the complex role of HV, in particular HV asymmetry, in predicting the emergence of PTSD symptoms in response to war-zone trauma.

On Sequential Bayesian Inference for Continual Learning.

Sequential Bayesian inference can be used for continual learning to prevent catastrophic forgetting of past tasks and provide an informative prior when learning new tasks. We revisit sequential Bayesian inference and assess whether using the previous task's posterior as a prior for a new task can prevent catastrophic forgetting in Bayesian neural networks. Our first contribution is to perform sequential Bayesian inference using Hamiltonian Monte Carlo. We propagate the posterior as a prior for new tasks by approximating the posterior via fitting a density estimator on Hamiltonian Monte Carlo samples. We find that this approach fails to prevent catastrophic forgetting, demonstrating the difficulty in performing sequential Bayesian inference in neural networks. From there, we study simple analytical examples of sequential Bayesian inference and CL and highlight the issue of model misspecification, which can lead to sub-optimal continual learning performance despite exact inference. Furthermore, we discuss how task data imbalances can cause forgetting. From these limitations, we argue that we need probabilistic models of the continual learning generative process rather than relying on sequential Bayesian inference over Bayesian neural network weights. Our final contribution is to propose a simple baseline called Prototypical Bayesian Continual Learning, which is competitive with the best performing Bayesian continual learning methods on class incremental continual learning computer vision benchmarks.

CO2 reactivity as a biomarker of exposure-based therapy non-response: study protocol.

BACKGROUND: Exposure-based therapy is an effective first-line treatment for anxiety-, obsessive-compulsive, and trauma- and stressor-related disorders; however, many patients do not improve, resulting in prolonged suffering and poorly used resources. Basic research on fear extinction may inform the development of a biomarker for the selection of exposure-based therapy. Growing evidence links orexin system activity to deficits in fear extinction and we have demonstrated that reactivity to an inhaled carbon dioxide (CO2) challenge-a safe, affordable, and easy-to-implement procedure-can serve as a proxy for orexin system activity and predicts fear extinction deficits in rodents. Building upon this basic research, the goal for the proposed study is to validate CO2 reactivity as a biomarker of exposure-based therapy non-response. METHODS: We will assess CO2 reactivity in 600 adults meeting criteria for one or more fear- or anxiety-related disorders prior to providing open exposure-based therapy. By incorporating CO2 reactivity into a multivariate model predicting treatment non-response that also includes reactivity to hyperventilation as well as a number of related predictor variables, we will establish the mechanistic specificity and the additive predictive utility of the potential CO2 reactivity biomarker. By developing models independently within two study sites (University of Texas at Austin and Boston University) and predicting the other site's data, we will validate that the results are likely to generalize to future clinical samples. DISCUSSION: Representing a necessary stage in translating basic research, this investigation addresses an important public health issue by testing an accessible clinical assessment strategy that may lead to a more effective treatment selection (personalized medicine) for patients with anxiety- and fear-related disorders, and enhanced understanding of the mechanisms governing exposure-based therapy. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05467683 (20/07/2022).

Mycorrhizal and rhizobial interactions influence model grassland plant community structure and productivity.

Arbuscular mycorrhizal (AM) fungi and rhizobium are likely important drivers of plant coexistence and grassland productivity due to complementary roles in supplying limiting nutrients. However, the interactive effects of mycorrhizal and rhizobial associations on plant community productivity and competitive dynamics remain unclear. To address this, we conducted a greenhouse experiment to determine the influences of these key microbial functional groups on communities comprising three plant species by comparing plant communities grown with or without each symbiont. We also utilized N-fertilization and clipping treatments to explore potential shifts in mycorrhizal and rhizobial benefits across abiotic and biotic conditions. Our research suggests AM fungi and rhizobium co-inoculation was strongly facilitative for plant community productivity and legume (Medicago sativa) growth and nodulation. Plant competitiveness shifted in the presence of AM fungi and rhizobium, favoring M. sativa over a neighboring C4 grass (Andropogon gerardii) and C3 forb (Ratibida pinnata). This may be due to rhizobial symbiosis as well as the relatively greater mycorrhizal growth response of M. sativa, compared to the other model plants. Clipping and N-fertilization altered relative costs and benefits of both symbioses, presumably by altering host-plant nitrogen and carbon dynamics, leading to a relative decrease in mycorrhizal responsiveness and proportional biomass of M. sativa relative to the total biomass of the entire plant community, with a concomitant relative increase in A. gerardii and R. pinnata proportional biomass. Our results demonstrate a strong influence of both microbial symbioses on host-plant competitiveness and community dynamics across clipping and N-fertilization treatments, suggesting the symbiotic rhizosphere community is critical for legume establishment in grasslands.

The Role of Social Support in Coping with Psychological Trauma: An Integrated Biopsychosocial Model for Posttraumatic Stress Recovery.

This theoretical review proposes an integrated biopsychosocial model for stress recovery, highlighting the interconnectedness of intra- and interpersonal coping processes. The proposed model is conceptually derived from prior research examining interpersonal dynamics in the context of stressor-related disorders, and it highlights interconnections between relational partner dynamics, perceived self-efficacy, self-discovery, and biological stress responsivity during posttraumatic recovery. Intra- and interpersonal processes are discussed in the context of pre-, peri-, and post-trauma stress vulnerability as ongoing transactions occurring within the individual and between the individual and their environment. The importance of adopting an integrated model for future traumatic stress research is discussed. Potential applications of the model to behavioral interventions are also reviewed, noting the need for more detailed assessments of relational dynamics and therapeutic change mechanisms to determine how relational partners can most effectively contribute to stress recovery.

Emotional Processing of Imaginal Exposures Predicts Symptom Improvement: Therapist Ratings Can Assess Trajectory in Prolonged Exposure for Posttraumatic Stress Disorder.

Research on mechanisms of change in prolonged exposure therapy (PE), an evidence-based treatment for posttraumatic stress disorder (PTSD), is ongoing. Two putative mechanisms of change are engagement during imaginal exposure and trauma-related belief change. The PE Therapist Questionnaire (PETQ), a novel measure based on the emotional processing theory underlying PE, was developed as a practical tool for therapists to use to assess (a) patient engagement during imaginal exposures and (b) perspective shifts during postimaginal processing. Patients (N = 151) at a U.S. Veterans Affairs medical center PTSD specialty clinic completed self-report measures of PTSD and depression symptoms prior to sessions. Study therapists (n = 17) completed the PETQ postsession. Rational construction and psychometric analyses suggested a two-component solution for the PETQ: imaginal and processing. The imaginal factor did not relate to PTSD and depression symptoms. The processing factor correlated with current and next-session PTSD and depression symptoms, with medium effect sizes, rs = -.41 to -.45, ps < .001. Controlling for current-session PTSD and depression, a higher level of processing predicted lower next-session PTSD severity, with a small effect size, ß = -.38, p < .04. Postexposure emotional processing, which supports positive changes in maladaptive trauma-related beliefs and tolerance of emotional distress, predicted future symptom improvement, highlighting the importance of processing components in PE. Further, the use of therapist observations may offer ancillary methods less influenced by correlation of within-patient subjective ratings and concomitant risk of construct overlap in mechanisms research.

Emotional reactivity to grief-related expressive writing.

The efficacy of expressive writing for bereavement remains unclear, although some evidence suggests that writing about positive memories of one's loved one may be particularly beneficial. The current pilot study compared the effects of a brief positive expressive writing intervention for enhancing positive affect among bereaved adults (N = 403). Participants were randomly assigned to write about a positive memory of the deceased person or recent neutral activity. Results revealed no main effect of the positive writing condition on mood change. However, greater positive emotion word use mediated positive affect among those in the positive writing condition.

Defoliation and arbuscular mycorrhizal fungi shape plant communities in overgrazed semiarid grasslands.

Overgrazing substantially contributes to global grassland degradation by decreasing plant community productivity and diversity through trampling, defoliation, and removal of nutrients. Arbuscular mycorrhizal (AM) fungi also play a critical role in plant community diversity, composition, and primary productivity, maintaining ecosystem functions. However, interactions between grazing disturbances, such as trampling and defoliation, and AM fungi in grassland communities are not well known. We examined influences of trampling, defoliation, and AM fungi on semiarid grassland plant community composition for 3 yr, by comparing all combinations of these factors. Benomyl fungicide was applied to reduce AM fungal abundance. Overgrazing typically resulted in reduced dominance of Stipa Krylovii, contributing to degradation of typical steppe grasslands. Our results indicated trampling generally had little effect on plant community composition, unless combined with defoliation or AM fungal suppression. Defoliation was the main component of grazing that promoted dominance of Potentilla acaulis over Stipa krylovii and Artemisia frigida, presumably by alleviating light limitation. In non-defoliated plots, AM fungi promoted A. frigida, with a concomitant reduction in S. krylovii growth compared to corresponding AM suppressed plots. Our results indicate AM fungi and defoliation jointly suppress S. krylovii biomass; however, prolonged defoliation weakens mycorrhizal influence on plant community composition. These findings give new insight into dominant plant species shifts in degraded semiarid grasslands.

Long-term effects of grazing and topography on extra-radical hyphae of arbuscular mycorrhizal fungi in semi-arid grasslands.

Grazing and topography have drastic effects on plant communities and soil properties. These effects are thought to influence arbuscular mycorrhizal (AM) fungi. However, the simultaneous impacts of grazing pressure (sheep ha-1) and topography on plant and soil factors and their relationship to the production of extra-radical AM hyphae are not well understood. Our 10-year study assessed relationships between grazing, plant species richness, aboveground plant productivity, soil nutrients, edaphic properties, and AM hyphal length density (HLD) in different topographic areas (flat or sloped). We found HLD linearly declined with increasing grazing pressure (1.5-9.0 sheep ha-1) in sloped areas, but HLD was greatest at moderate grazing pressure (4.5 sheep ha-1) in flat areas. Structural equation modeling indicates grazing reduces HLD by altering soil nutrient dynamics in sloped areas, but non-linearly influences HLD through plant community and edaphic changes in flat areas. Our findings highlight how topography influences key plant and soil factors, thus regulating the effects of grazing pressure on extra-radical hyphal production of AM fungi in grasslands. Understanding how grazing and topography influence AM fungi in semi-arid grasslands is vital, as globally, severe human population pressure and increasing demand for food aggravate the grazing intensity in grasslands.

Perceived childhood family cohesiveness prior to deployment prospectively moderates risk for war-zone psychopathology in theater among deployed U.S. soldiers.

OBJECTIVE: Several studies have demonstrated robust protective effects of childhood family support and cohesiveness on adult stress-related psychopathology. However, there is little evidence regarding the prospective relationship between the perceived childhood family environment and the in-theater emergence of war-zone stress-related psychological symptoms. The present report is from data collected from the Texas Combat PTSD Risk Project, which aims to identify risk and resilience factors at predeployment that predict the subsequent impact of war-zone stressors in terms of psychological symptom emergence in U.S. soldiers deployed to Iraq. METHOD: Soldiers (N = 150) completed a battery of standardized interview and self-report assessments at predeployment, including a measure of perceived childhood family cohesion. Once deployed, soldiers completed monthly web-based self-report assessments of war-zone stressors, posttraumatic stress symptoms, depression, and anxiety. RESULTS: Consistent with predictions, greater perceived childhood family cohesiveness prior to deployment robustly mitigated subsequent in-theater symptoms. However, contrary to predictions, childhood family cohesiveness did not reliably moderate the linkage between war-zone stressors and in-theater symptoms. CONCLUSIONS: Consistent with a wealth of other evidence demonstrating protective stress resilience effects of childhood family cohesion that extend across the lifespan, the present findings suggest they also extend to the war-zone environment among deployed soldiers. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Effects of Commercial Arbuscular Mycorrhizal Inoculants on Plant Productivity and Intra-Radical Colonization in Native Grassland: Unintentional De-Coupling of a Symbiosis?

There has been a surge in industries built on the production of arbuscular mycorrhizal (AM) fungal-based inoculants in the past few decades. This is not surprising, given the positive effects of AM fungi on plant growth and nutritional status. However, there is growing concern regarding the quality and efficacy of commercial inoculants. To assess the potential benefits and negative consequences of commercial AM fungal inoculants in grasslands, we conducted a controlled growth chamber study assessing the productivity and AM fungal root colonization of nine grassland plant species grown in grassland soil with or without one of six commercial AM fungal products. Our research showed no evidence of benefit; commercial inoculants never increased native plant biomass, although several inoculants decreased the growth of native species and increased the growth of invasive plant species. In addition, two commercial products contained excessive levels of phosphorus or nitrogen and consistently reduced AM fungal root colonization, indicating an unintentional de-coupling of the symbiosis. As there is little knowledge of the ecological consequences of inoculation with commercial AM fungal products, it is critical for restoration practitioners, scientists, and native plant growers to assess the presence of local AM fungal communities before investing in unnecessary, or possibly detrimental, AM fungal products.

Assessing soil microbes that drive fairy ring patterns in temperate semiarid grasslands.

BACKGROUND: Fairy rings occur in diverse global biomes; however, there is a critical knowledge gap regarding drivers of fairy rings in grassland ecosystems. Grassland fairy rings are characterized belowground by an expanding mycelial front and aboveground by vigorous vegetation rings that develop concentrically with each growing season. We evaluated fairy ring dynamics in a field study conducted in semiarid grasslands to elucidate above- and belowground interactions driving distinct vegetation patterns. We followed this initial field investigation with a complementary greenhouse experiment, using soils collected from specific fairy ring zones (inside, ring-edge, outside) to examine plant-soil-microbial interactions under controlled conditions. We selected Leymus chinensis (a dominant grass) as our model plant species to assess the role of diverse fairy ring microbial communities on plant growth and nutrition. RESULTS: In our field study, plants on the ring-edge produced greater shoot biomass with higher concentrations of N and P, compared to plants inside the ring or adjacent (outside) controls. Soil microbial community biomarkers indicate shifts in relative microbial biomass as fairy rings expand. Inside the ring, plant roots showed greater damage from pathogenic fungi, compared to outside or ring-edge. Our greenhouse experiment confirmed that inoculation with live ring-edge soil generally promoted plant growth but decreased shoot P concentration. Inoculation with soil collected from inside the ring increased root pathogen infection and reduced shoot biomass. CONCLUSION: We propose that soil microbial activity within ring-edges promotes plant growth via mobilization of plant-available P or directed stimulation. However, as the ring expands, L. chinensis at the leading edge may increase pathogen accumulation, resulting in reduced growth at the center of the ring in subsequent growing seasons. Our results provide new insights into the plant-soil-microbial dynamics of fairy rings in grasslands, helping to elucidate these mysterious vegetation patterns.

Technology-enhanced in vivo exposures in Prolonged Exposure for PTSD: A pilot randomized controlled trial.

In vivo exposures (IVEs) are a key component of exposure-based treatments, during which patients approach fear-provoking, yet safe, situations in "real life." This pilot study assessed the use of a wearable technology (Bio Ware) during IVEs to enhance Prolonged Exposure (PE) therapy for PTSD. Bio Ware provides a clinician dashboard with real-time physiological and subjective data for clinicians to use for virtually guided IVEs. Participants (N = 40) were randomized to a Guided group that received standard PE and virtual, clinician-guided IVEs with the Bio Ware device, or a Non-Guided group that received standard PE and used the Bio Ware device on their own for IVEs. Multilevel linear models with bootstrapping were completed on the intent-to-treat (ITT; N = 39) and per-protocol samples (PP; n = 23), defined as completing at least eight sessions of PE and using the Bio Ware system during ≥ 1 IVEs. In the PP sample, there were significant effects of treatment condition (b = -14.55, SE = 1.47, 95% CI [-17.58, -11.78], p < .001) and time (b = -1.98, SE = 0.25, 95% CI [-2.47, -1.48], p < .001). While both groups showed reductions in PTSD symptoms, the Guided group evidenced significantly greater reductions than the Non-Guided group. These findings demonstrate the feasibility and safety of leveraging Bio Ware for virtual, clinician-guided IVEs during PE therapy for PTSD and suggest that virtual, clinician-guided exposures may enhance treatment outcomes. CLINICAL TRIAL REGISTRATION: NCT04471207.

tDCS-Augmented in vivo exposure therapy for specific fears: A randomized clinical trial.

Exposure therapy is highly effective for anxiety-related disorders, but there is a need for enhancement. Recent trials of adjunctive neuromodulation have shown promise, warranting evaluation of transcranial direct current stimulation (tDCS) as an augmentation. In a double-blind, placebo-controlled trial, contamination- and animal-phobic participants (N = 49) were randomized to active tDCS (1.7 mA, 20 min; n = 27), or sham tDCS (1.7 mA, 30 s; n = 22), followed by 30 min of in-vivo exposure. Active tDCS targeted excitation of the left mPFC and inhibition of the right dlPFC; polarity was counterbalanced for controls. We predicted tDCS would result in accelerated and better maintained gains, contingent on the subsequent in-session response, and baseline negative prognostic indicators. Consistent with predictions, tDCS promoted engagement and reductions in threat appraisals during exposure, and greater reductions in distress and threat appraisals through 1-month, although effects did not uniformly generalize. tDCS was most beneficial given high phobic severity, anxiety sensitivity, and a suboptimal early response. tDCS may promote engagement and response among individuals who are resistant or refractory to standard treatment. tDCS should be applied to more severe anxiety-related disorders, with parameters yoked to individual differences to improve outcomes in exposure-based interventions.

Evidence that episodic memory impairment during tobacco abstinence is independent of attentional mechanisms.

Previous studies have demonstrated reductions in episodic memory during nicotine withdrawal. However, these studies have been unable to dissociate memory reductions from losses in attention associated with tobacco abstinence. In the present study, the authors sought to determine whether episodic memory reduction is a primary effect of nicotine withdrawal during tobacco abstinence. Heavy smokers were tested when smoking normally and following 24 hrs of abstinence. Participants were tested with a recognition memory task in which items were studied under full and divided attention conditions. Forward digit span and backward digit span were also included as control measures. Withdrawal was associated with a reduction in memory performance that was independent of attention at encoding. The authors conclude that impairment of episodic memory is a primary effect of nicotine withdrawal during tobacco abstinence. Further research is required to determine if this is associated with continued use of tobacco and cessation failures.

Determining landscape-level drivers of variability for over fifty soil chemical elements.

Syntheses of large datasets have allowed increased clarity of distribution patterns and variation in soil major and trace elements. However, the drivers of variation in topsoil elements across biogeographical scales are not well understood. Our aim was to (1) identify how landscape-scale climate, geographical features, and edaphic factors influence soil elements, and (2) determine key environmental thresholds for shifts in soil element concentration. We analyzed patterns of variation in topsoil elements using 9830 samples collected across 39,000km2 in subtropical land in southeast China. Canonical correlations and multiple linear regressions were used to model variations of each element across mean annual temperature (MAT), mean annual precipitation (MAP), land use, spatial topography, and soil pH. Element concentrations show significant latitudinal and longitudinal trends, and are significantly influenced by climate, land use, spatial topography, and soil pH. Longitude, pH, MAT, and MAP were the environmental factors most tightly correlated with element concentrations. Climate and soil pH drove positive or negative alterations in soil elements, with threshold indicators of MAP=1000mm/1500mm, MAT=17.8°C/18.0°C, and pH=5.8/5.0, respectively. Our results indicate topsoil elements have structural and functional thresholds of climate and soil pH in relatively wet and acidic environments. Our findings can facilitate holistic soil element concentration predictions and help elucidate the specific influences of climate and soil pH, enabling development of more complete biogeochemical models.

New Magnetostrictive Transducer Designs for Emerging Application Areas of NDE.

Magnetostrictive transduction has been widely utilized in nondestructive evaluation (NDE) applications, specifically for the generation and reception of guided waves for the long-range inspection of components such as pipes, vessels, and small tubes. Transverse-motion guided wave modes (e.g., torsional vibrations in pipes) are the most common choice for long-range inspection applications, because the wave motion is in the plane of the structure surface, and therefore does not couple well to the surrounding material. Magnetostrictive-based sensors for these wave modes using the Wiedemann effect have been available for several years. An alternative configuration of a sensor for generating and receiving these transverse-motion guided waves swaps the biasing and time-varying magnetic field directions. This alternative design is a reversed Wiedemann effect magnetostrictive transducer. These transducers exhibit a number of unique features compared with the more conventional Wiedemann sensor, including: (1) the use of smaller rare earth permanent magnets to achieve large, uniform, and self-sustained bias field strengths; (2) the use of more efficient electric coil arrangements to induce a stronger time-varying magnetic field for a given coil impedance; (3) beneficial non-linear operating characteristics, given the efficiency improvements in both magnetic fields; and (4) the ability to generate unidirectional guided waves when the field arrangement is combined with a magnetically soft ferromagnetic strip (patch). Reversed Wiedemann effect magnetostrictive transducers will be presented that are suitable for different inspection applications, one using electromagnetic generation and reception directly in a ferromagnetic material, and another design that integrates a magnetostrictive patch to improve its efficiency and enable special operating characteristics.

Influence of alternative soil amendments on mycorrhizal fungi and cowpea production.

Alternative soil amendments (worm compost, pyrolyzed carbon [biochar]) and crop symbioses with arbuscular mycorrhizal (AM) fungi have the potential to reduce food production costs while promoting sustainable agriculture by improving soil quality and reducing commercial (N and P) fertilizer use. Our greenhouse studies investigated the influence of alternative soil amendments on AM fungi associated with cowpea (Vigna unguiculata [L.] Walp.) and common bean (Phaseolus vulgaris L.) by examining productivity and plant nutrition. We conducted an experiment to select a cowpea or common bean genotype based on AM fungal colonization, seed production, and seed nutritional content. We then grew the selected cowpea genotype (Resina) in low-fertility soil with 10 different soil amendments (combinations of biochar, worm compost, and/or commercial fertilizers) plus a non-amended control. There were no significant differences in AM fungal colonization of cowpea plants grow with different soil amendments. However, an amendment blend containing worm compost, biochar, and 50% of the typically recommended commercial fertilizer rate produced plants with similar aboveground biomass, protein concentration, and total protein production, with increased tissue K, P, and Zn concentration and total content, compared to plants receiving only the recommended (100%) rate of commercial fertilizer. As previous research links uptake of P and Zn with plant-mycorrhizal symbioses, our results indicate cowpea nutritional benefits may be derived from AM partnership and alternative soil amendments. These synergies between alternative soil amendments and AM fungi may help reduce farm costs while maintaining or improving crop yield and nutrition, thus increasing global food and nutrition security.

Trichoderma Biofertilizer Links to Altered Soil Chemistry, Altered Microbial Communities, and Improved Grassland Biomass.

In grasslands, forage and livestock production results in soil nutrient deficits as grasslands typically receive no nutrient inputs, leading to a loss of grassland biomass. The application of mature compost has been shown to effectively increase grassland nutrient availability. However, research on fertilization regime influence and potential microbial ecological regulation mechanisms are rarely conducted in grassland soil. We conducted a two-year experiment in meadow steppe grasslands, focusing on above- and belowground consequences of organic or Trichoderma biofertilizer applications and potential soil microbial ecological mechanisms underlying soil chemistry and microbial community responses. Grassland biomass significantly (p = 0.019) increased following amendment with 9,000 kg ha-1 of Trichoderma biofertilizer (composted cattle manure + inoculum) compared with other assessed organic or biofertilizer rates, except for BOF3000 (fertilized with 3,000 kg ha-1 biofertilizer). This rate of Trichoderma biofertilizer treatment increased soil antifungal compounds that may suppress pathogenic fungi, potentially partially responsible for improved grassland biomass. Nonmetric multidimensional scaling (NMDS) revealed soil chemistry and fungal communities were all separated by different fertilization regime. Trichoderma biofertilizer (9,000 kg ha-1) increased relative abundances of Archaeorhizomyces and Trichoderma while decreasing Ophiosphaerella. Trichoderma can improve grassland biomass, while Ophiosphaerella has the opposite effect as it may secrete metabolites causing grass necrosis. Correlations between soil properties and microbial genera showed plant-available phosphorus may influence grassland biomass by increasing Archaeorhizomyces and Trichoderma while reducing Ophiosphaerella. According to our structural equation modeling (SEM), Trichoderma abundance was the primary contributor to aboveground grassland biomass. Our results suggest Trichoderma biofertilizer could be an important tool for management of soils and ultimately grassland plant biomass.

Cortisol, Testosterone, and Prospective Risk for War-zone Stress-Evoked Depression.

Introduction: The major challenges of efforts to reveal biological risk factors and biomarkers of depression include the complexity of underlying systems, interactions with other systems, and contextual factors governing their expression. Altered endocrine function is believed to be a central contributor to depressive illness, but across studies, evidence for a link between endocrine markers and depression has been mixed, inconclusive, or conditional in nature. In the present study, we evaluated basal testosterone (T), cortisol (C), and CO2 inhalation-stress-reactivity measures of these hormones (TR, CR) as pre-deployment moderators of the later impact of war-zone stressors on depression symptoms in-theater. Materials and Methods: At pre-deployment, U.S. soldiers (N = 120) completed demographic, clinical and hormone measures, and during deployment, they completed monthly, web-based assessments of war-zone stressors and depression symptoms (N = 533 observations). Mixed effects models estimated the effects of the pre-deployment hormone profiles in moderating war-zone stressors' impact on in-theater depression. Models also tested whether hormonally linked risk for later stress-evoked depression depends on pre-existing depression. Results: Controlling for pre-deployment depression, high T was protective; whereas TR had depressogenic effects that were amplified by pre-deployment depression. Further, high C was protective, but heightened CR was depressogenic, but only among those with elevated pre-deployment depression. Conclusions: Findings highlight the importance of examining basal and reactivity measures of endocrine function, and use of prospective, longitudinal models to test hypothesized causal pathways associated with depression vulnerability in the war-zone. Results also suggest that pre-existing depression and cortisol may work in tandem to increase vulnerability for later stress-evoked depression in the war-zone.